System and method for coupling purification and conversion heat of coal pyrolysis raw gas

Abstract

The invention discloses a system and a method for coupling purification and conversion heat of coal pyrolysis raw gas. The coal pyrolysis raw gas purification and conversion heat coupling system comprises an inlet and outlet heat exchanger, a detoxification tank, a deoxidation furnace, a dechlorination furnace, a washing humidifying tower, a gas preheater, a dechlorination tank and a first heat insulation furnace, an inlet of the detoxification tank is communicated with an outlet of the heat absorption side of the inlet and outlet heat exchanger, and the detoxification tank, the deoxidation furnace, the dechlorination furnace and the washing humidifying tower are sequentially communicated; an inlet of the heat absorption side of the gas preheater is communicated with the washing humidifying tower, an inlet of the dechlorination tank is communicated with an outlet of the heat absorption side of the gas preheater, an outlet of the dechlorination tank is communicated with an inlet of the first adiabatic furnace, and an outlet of the first adiabatic furnace is sequentially communicated with the heat release side of the gas preheater and the heat release side of the inlet and outlet heat exchanger. Multi-stage coupling of high-level heat and low-level heat and accurate and effective removal of impurities are completed through heat grading matching, excessive use of steam and electric energy is avoided, and process heat coupling and flow optimization are achieved.

Description

Technical Field

[0001] This invention relates to the fields of coal chemical industry and environmental protection. Specifically, this invention relates to a system and method for purifying and converting raw coal gas from coal pyrolysis. Background Technology

[0002] my country's energy resource structure is generally characterized by "abundant coal, scarce oil, and limited gas." This resource endowment necessitates the development of the coal chemical industry, and the efficient utilization of coal resources, especially the upgrading of low-rank coal, is a major energy issue for the development of modern coal chemical industry. Low-rank coal low-temperature pyrolysis technology can yield products such as coal tar, semi-coke, and raw coal gas. Raw coal gas is rich in CO and H2 resources. By rationally purifying and adjusting the hydrogen-to-carbon ratio of the syngas through CO conversion technology, it can extend downstream into mid-to-high-end product chains such as methanol and ethanol, demonstrating high utilization value.

[0003] The purification process for raw coal gas differs from current mainstream coal gasification and coke oven gas technologies due to the diverse and uncertain composition of impurities in raw coal gas, such as organic matter and unsaturated harmful impurities. Raw coal gas from coal pyrolysis is a gaseous product obtained by upgrading oil-rich coal through a low-temperature pyrolysis process. Coal pyrolysis technology is limited by the characteristics of low-temperature dry distillation (<900℃), resulting in the generation of large amounts of low-temperature dry distillation products (benzene, naphthalene, tar, and organic impurities, etc.) and phenolic and ammonia wastewater. The easily volatile impurities in raw coal are mainly concentrated in raw coal gas. Compared to coke oven gas, the impurities in raw coal gas contain benzene, naphthalene, tar, unsaturated hydrocarbons, oxygen, organic sulfur, and organic chlorine, making it more complex, variable, and difficult to purify. Furthermore, the content of major gaseous components such as CO, H2, CH4, and CO2 in raw coal gas varies significantly, leading to substantial differences in the purification process. Poor handling of the raw coal gas purification process can frequently cause shutdowns for maintenance, affecting production. Summary of the Invention

[0004] This invention is based on the inventors' discoveries and understanding of the following facts and problems: the purification and conversion process of raw coal gas from coal pyrolysis differs from both pressurized coal gasification and coke oven gas technologies. Pressurized coal gasification involves high reaction temperatures (1300~1500℃), effectively converting harmful impurities in the coal into harmless ones. The purification process is relatively simple and has already formed a mature and reliable technical route. The purification process for coke oven gas, after preliminary exploratory experiments, has also formed a mature and reliable technical route. However, the purification process of coal pyrolysis gas, a byproduct of low-rank coal pyrolysis, differs from both coal gasification and coke oven gasification. Limited by the reaction temperature and the different pyrolysis media (pure oxygen, oxygen-enriched gas, and air, etc.), it is currently still in the exploratory and development stage, lacking a mature technical route. The reliability of related industrial operation equipment is poor, and a reliable technical route is urgently needed to guide development and production.

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a system and method for coupling the purification and conversion heat of raw coal gas from coal pyrolysis. Through heat grading and matching, the heat from the sulfur-resistant conversion reaction is coupled for hydrodeoxygenation, hydrodechlorination, hydrodesulfurization, and hydrogenation of unsaturated hydrocarbons. Impurities are precisely and effectively removed, avoiding excessive use of superheated steam and electricity, and achieving process heat coupling and process optimization.

[0006] This invention provides a system for purifying and converting heat in coal pyrolysis raw coal gas, comprising: An inlet and outlet heat exchanger has a first heat release side and a first heat absorption side, and the inlet of the first heat absorption side is used to introduce pre-purified coal pyrolysis gas. A detoxification tank, wherein the inlet of the detoxification tank is connected to the outlet of the first heat absorption side; A deoxidizer furnace, wherein the inlet of the deoxidizer furnace is connected to the outlet of the detoxification tank; A dechlorination furnace, wherein the inlet of the dechlorination furnace is connected to the outlet of the deoxygenation furnace; A washing and humidifying tower is provided with a first inlet and a first outlet, and the first inlet of the washing and humidifying tower is connected to the outlet of the dechlorination furnace; A gas preheater, the gas preheater having a second heat release side and a second heat absorption side, the inlet of the second heat absorption side being connected to the first outlet, and the outlet of the second heat release side being connected to the inlet of the first heat release side. A dechlorination tank, the inlet of which is connected to the outlet of the second heat absorption side; The first adiabatic furnace has its inlet connected to the outlet of the dechlorination tank, and its outlet is connected to the inlet of the second heat release side.

[0007] The advantages and technical effects of the coal pyrolysis raw gas purification and heat conversion coupling system of this invention are as follows: The coal pyrolysis raw gas purification and heat conversion coupling system can realize the coupling of purification and sulfur-resistant heat conversion during the impurity removal process of coal pyrolysis raw gas. It analyzes the energy characteristics of oxygen hydrogenation, organochlorine, subsequent organosulfur and unsaturated hydrocarbon hydrogenation and adiabatic conversion processes. According to the energy requirements of hydrogenation detoxification and adiabatic conversion, the process energy is reasonably graded, coupled and matched. This includes the coupling process of sulfur-resistant heat conversion from the first adiabatic furnace to hydrogenation deoxygenation in the deoxidation furnace via inlet and outlet heat exchangers, hydrogenation deoxygenation heat from the deoxidation furnace to hydrogenation dechlorination in the dechlorination furnace, and sulfur-resistant heat conversion from the first adiabatic furnace to catalyst activation and hydrogenation desulfurization and unsaturated hydrocarbon hydrogenation in the hydrogenation furnace. The system of this invention removes impurity components in a step-by-step and graded manner based on the characteristics of each impurity through system optimization and energy coupling. In particular, it removes difficult-to-handle organic sulfur, organic chlorine, oxygen, and unsaturated hydrocarbons. It makes full use of the characteristic that these impurities require high-temperature hydrogenation for removal, and couples the heat of the reaction to achieve precise and effective removal of impurities. It solves the difficulties in heat grading and matching and segmented removal of impurities in the process of removing toxic substances such as oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons in the purification of raw coal gas. It overcomes the drawbacks of traditional hydrogenation processes that rely too much on high-quality superheated steam and electric heating, and achieves the multiple benefits of effective impurity purification, process optimization, energy grading coupling, and energy saving and environmental protection.

[0008] In this embodiment of the invention, the utilization of high-grade heat and low-grade heat achieves multi-stage coupling, resulting in high-efficiency utilization. It features a short process flow, full utilization of waste heat, reduced consumption of high-grade steam, rational energy utilization, simple operation, low investment costs, and low operation and maintenance costs. The energy coupling process makes the utilization of raw coal gas more rational, safe, stable, and energy-saving, with high feasibility, reasonable energy-stage coupling, and a simple process. Subsequently, the syngas, after adjusting the hydrogen-to-carbon ratio, undergoes desulfurization and decarbonization, and can be applied to the synthesis of methanol, ethanol, ethylene glycol, natural gas, ammonia, etc., as well as the production of H2 and other high-value effective gases (H2 and CO) in chemical industries. The syngas product has high quality, and the technology has strong scalability.

[0009] In some embodiments, an electric heater is further included, the inlet of which is connected to the outlet of the first heat absorption side, and the outlet of which is connected to the inlet of the detoxification tank; And / or, the washing and humidifying tower has an upper part and a lower part, the upper part being located downstream of the lower part; The first inlet is located in the lower half, and the first outlet is located in the upper half; The lower part is also provided with a second inlet and a second outlet. The second inlet is used to connect to a water source, and the second outlet is used to discharge condensate. The upper part is also provided with a third inlet, which is used to introduce humidifying steam.

[0010] In some embodiments, the system further includes a first hydrogenation furnace, the inlet of which is connected to the outlet of the first adiabatic furnace, and the outlet of the first hydrogenation furnace is connected to the inlet of the second exothermic side. And / or, also includes a humidifier, a second insulated furnace, and a second hydrogenation furnace, The humidifier is provided with a first gas inlet, a first gas outlet and a humidifying steam inlet. The first gas inlet is connected to the outlet on the first heat-releasing side, and the humidifying steam inlet is used to introduce humidifying steam. The inlet of the second adiabatic furnace is connected to the outlet of the first gas. The inlet of the second hydrogenation furnace is connected to the outlet of the second adiabatic furnace.

[0011] In some embodiments, a waste heat recovery heat exchanger is further included, the waste heat recovery heat exchanger having a third heat-releasing side and a third heat-absorbing side; the inlet of the third heat-releasing side is connected to the outlet of the first heat-releasing side, or the inlet of the third heat-releasing side is connected to the outlet of the second hydrogenation furnace.

[0012] In some embodiments, the system further includes an ammonia washing tower, which has a fourth inlet, a fourth outlet, a fifth inlet, and a fifth outlet. The fourth inlet is connected to the outlet on the third exothermic side, the fourth outlet is used to discharge synthesis gas, the fifth inlet is used to connect to a water source, and the fifth outlet is connected to the second inlet.

[0013] In some embodiments, a desulfurization and decarbonization device is also included, wherein the inlet of the desulfurization and decarbonization device is connected to the fourth outlet.

[0014] In some embodiments, a preliminary purification unit is further included, which includes an electrostatic precipitator, a low-temperature water washing device, and a compression device. The inlet of the electrostatic precipitator is used to introduce coal pyrolysis gas. The low-temperature water washing device is provided with a sixth inlet, a sixth outlet, a seventh inlet, and a seventh outlet. The sixth inlet is connected to the outlet of the electrostatic precipitator, the seventh inlet is connected to the second outlet, and the seventh outlet is used to discharge liquid. The inlet of the compression device is connected to the sixth outlet, and the outlet of the compression device is connected to the inlet of the first heat absorption side.

[0015] In some embodiments, the device further includes a gas holder, the inlet of which is connected to the outlet of the electrostatic precipitator, and the outlet of which is connected to the sixth inlet of the low-temperature water washing device. And / or, the compression device includes a first compression device, a removal device, and a second compression device, wherein the inlet of the first compression device is the inlet of the compression device, the outlet of the first compression device is connected to the inlet of the removal device, the outlet of the removal device is connected to the inlet of the second compression device, and the outlet of the second compression device is the outlet of the compression device; And / or, it also includes a separator having an eighth inlet, an eighth outlet and a ninth outlet, the eighth inlet being connected to the outlet of the compression device, the eighth outlet being connected to the inlet of the first heat absorption side, and the ninth outlet being connected to the second inlet.

[0016] This invention provides a method for purifying and converting raw coal gas from coal pyrolysis using a coupled heat exchanger. The method employs the system described in this invention to purify and convert raw coal gas from coal pyrolysis, and includes the following steps: (1) The raw coal gas from coal pyrolysis is heated after preliminary purification, and then detoxified by a detoxifying adsorbent; after detoxification, it undergoes a hydrogenation deoxygenation reaction to remove oxygen; after hydrogenation deoxygenation, it undergoes an organic chlorine hydrogenation reaction to convert organic chlorine into inorganic chlorine, and then the inorganic chlorine is initially removed by washing, and then humidified by humidifying steam to obtain humidified gas. (2) The humidifying gas is heated and then the inorganic chlorine is further removed by protective adsorption dechlorination through a dechlorination adsorbent; after dechlorination, the first adiabatic transformation reaction is carried out; the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas.

[0017] In this embodiment of the invention, the method of coupling purification and heat conversion of raw coal gas from coal pyrolysis can achieve the coupling of purification and sulfur-resistant heat conversion during the removal of impurities from raw coal gas from coal pyrolysis. It analyzes the energy characteristics of oxygen hydrogenation, organochlorine, subsequent organosulfur and unsaturated hydrocarbon hydrogenation and adiabatic conversion processes. According to the energy requirements of hydrogenation detoxification and adiabatic conversion, the process energy is reasonably graded, coupled and matched. This includes the coupling process of using sulfur-resistant heat conversion to heat the initially purified raw coal gas for detoxification and hydrogenation deoxygenation, using hydrogenation deoxygenation heat for hydrogenation dechlorination, and using sulfur-resistant heat conversion to activate the catalyst and perform hydrogenation reaction desulfurization and unsaturated hydrocarbon coupling. The method of this invention removes impurity components in a step-by-step and graded manner based on the characteristics of each impurity through process optimization and energy coupling. In particular, it removes difficult-to-handle organic sulfur, organic chlorine, oxygen, and unsaturated hydrocarbons, making full use of their requirement for high-temperature hydrogenation removal. By coupling the heat of the conversion reaction, it achieves precise and effective removal of impurities. This solves the difficulties in heat grading and segmented impurity removal in the process of removing toxic substances such as oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons from raw coal gas. It overcomes the drawbacks of traditional hydrogenation processes that rely excessively on high-quality superheated steam and electric heating, achieving the multiple benefits of effective impurity purification, process optimization, energy grading coupling, and energy saving and environmental protection.

[0018] In some embodiments, in step (1), the preliminary purification includes: electrostatic precipitator to remove tar and dust from the coal pyrolysis raw coal gas, followed by water washing to further remove tar and dust, and then compression after water washing; And / or, the preliminarily purified raw coal gas is heated to a temperature of 260~280℃; And / or, the preliminarily purified raw coal gas includes at least one of the following: impurities containing lone pairs of electrons, oxygen, organochlorine, organosulfur, and unsaturated hydrocarbons; And / or, in step (1), the detoxification includes removing impurities containing lone pairs of electrons; And / or, the detoxifying adsorbent includes at least one of ZnO, MgO, CaO, CaCO3, Na2CO3 or K2CO3; And / or, the detoxification temperature is 260~280℃; And / or, in step (1), the hydrodeoxygenation reaction is carried out under the catalysis of a first catalyst; the first catalyst includes at least one of a Co-Mo catalyst or an Fe-Mo catalyst; And / or, the initial temperature of the hydrodeoxygenation reaction is 260~280℃, and the outlet temperature is 330~380℃.

[0019] In some embodiments, in step (1), the organochlorine hydrogenation reaction is carried out under the catalysis of a second catalyst; the second catalyst includes at least one of Pd, Pt, Rh, Ni, Co, Cu or Fe; And / or, the temperature of the organochlorine hydrogenation reaction is not lower than 350°C; And / or, in step (1), the washing includes washing with water; And / or, in step (1), the humidifying steam includes at least one of saturated steam or superheated steam; And / or, the temperature of the humidifying gas is 160~200℃.

[0020] In some embodiments, in step (2), the temperature of the heated humidifying gas is 220~260°C; And / or, in step (2), the dechlorination adsorbent includes at least one of CaO, MgO, CuO, ZnO, Na2CO3, NaHCO3, Ca(OH)2 or Mg(OH)2; And / or, the temperature for the protective adsorption dechlorination is 220~260℃; And / or, in step (2), the initial activation temperature of the first adiabatic transformation reaction is 220~260℃; And / or, the outlet temperature of the first adiabatic conversion reaction is 350~400℃; And / or, the first adiabatic shift reaction is carried out under the catalysis of a third catalyst, the third catalyst including a Co-Mo based sulfur-resistant shift catalyst.

[0021] In some embodiments, in step (2), the gas after the first adiabatic transformation undergoes a first hydrogenation reaction to convert organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively. The resulting gas is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas.

[0022] In some embodiments, the temperature of the first hydrogenation reaction is 350~380°C; And / or, the first hydrogenation reaction is carried out under the catalysis of a fourth catalyst, the fourth catalyst including a Co-Mo based hydrogenation catalyst; And / or, the resulting gas, after being cooled by the humidifying gas, has a temperature of 270~340℃; And / or, the resulting gas, after being cooled from the pre-purified raw coal gas, has a temperature of 140~220℃; And / or, the resulting gas is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas, and then cooled again.

[0023] In some embodiments, in step (2), the gas after the first adiabatic transformation is cooled by the humidifying gas and the temperature is 340~360℃; And / or, after the gas undergoing the first adiabatic transformation is cooled by the pre-purified raw coal gas, the temperature is 240~260℃; And / or, the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas, then humidified again by humidifying steam, and then undergoes the second adiabatic transformation reaction; the gas after the second adiabatic transformation undergoes the second hydrogenation reaction, converting organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively, to obtain syngas.

[0024] In some embodiments, in step (2), the humidifying steam includes saturated steam; And / or, the temperature of the gas after rehumidification is 220~240℃; And / or, the outlet temperature of the second adiabatic conversion reaction is 270~300℃; And / or, the second adiabatic shift reaction is carried out under the catalysis of a fifth catalyst, which includes a Co-Mo based sulfur-resistant shift catalyst; And / or, the temperature of the second hydrogenation reaction is 270~300℃; And / or, the second hydrogenation reaction is carried out under the catalysis of a sixth catalyst, which includes a Co-Mo based hydrogenation catalyst; And / or, the gas obtained after the second hydrogenation reaction is cooled again.

[0025] In some embodiments, in step (2), the cooled gas is subjected to ammonia washing to obtain syngas; preferably, the syngas after ammonia washing is subjected to desulfurization and decarbonization. And / or, the syngas is used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

[0026] This invention provides a synthesis gas, which is obtained by using the method described in this invention to obtain raw coal gas from coal pyrolysis.

[0027] This invention provides an application of syngas, which is used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen. Attached Figure Description

[0028] Figure 1 This is a simplified process flow diagram of the coal pyrolysis raw coal gas to syngas preparation of the present invention.

[0029] Figure 2 This is a simplified system flow diagram of the purification and heat conversion coupling of raw coal gas from coal pyrolysis in Embodiment 2 of the present invention.

[0030] Figure 3 This is a simplified system flow diagram of the purification and isothermal heat conversion coupling of raw coal gas from coal pyrolysis in Comparative Example 1 of the present invention.

[0031] Figure 4 This is a simplified system flow diagram of the purification and heat conversion coupling of raw coal gas from coal pyrolysis in Embodiment 3 of the present invention.

[0032] Figure 5 This is a simplified system flow diagram of the purification and heat conversion coupling of raw coal gas from coal pyrolysis in Embodiment 4 of the present invention.

[0033] Figure label: 1. Inlet and outlet heat exchanger, 2. Detoxification tank, 3. Deoxygenation furnace, 4. Dechlorination furnace, 5. Washing and humidifying tower, 6. Gas preheater, 7. Dechlorination tank, 8. First adiabatic furnace, 9. First hydrogenation furnace, 10. Humidifier, 11. Second adiabatic furnace, 12. Second hydrogenation furnace, 13. Waste heat recovery heat exchanger, 14. Ammonia washing tower, 15. Electric heater, 16. Separator, 17. Condensate pump. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] This invention provides a system and method for purifying and coupling heat conversion of raw coal pyrolysis gas. It has no special limitations on raw coal pyrolysis gas and can be applied to different types of raw coal pyrolysis gas. For example, the raw coal pyrolysis gas can be from raw coal pyrolysis gas produced by different processes. The system and method can be extended to the purification routes of raw coal pyrolysis gas from various pyrolysis furnace types.

[0036] The following description, based on the composition of raw coal pyrolysis gas from the outlet of a coal pyrolysis unit using a pure oxygen environment (as shown in Table 1), illustrates the present invention and is intended to explain the invention, not to limit it. The compositions specified in Table 1 are solely for illustrating the technical details and features of the invention.

[0037] Table 1

[0038] From the composition of the raw coal gas from the coal pyrolysis unit in this pure oxygen environment, it is clear that the raw coal gas contains abundant CO and H2 resources, making it a good chemical raw material for synthesizing methanol, ethanol, etc. The key challenge in utilizing raw coal gas lies in the purification of impurities and the thermal coupling with the shift reaction. Unsaturated hydrocarbons, organic sulfur compounds, organic chlorine compounds, and harmful toxins (such as O2, NH3, SO2, and HCN) in the raw coal gas all need to be removed by hydrogenation under high-temperature conditions. One of the difficulties is how to reduce excessive reliance on high-quality thermal energy such as superheated steam and electricity during the impurity removal process, thereby reducing consumption.

[0039] An embodiment of the present invention discloses a system for purifying and coupling heat exchange of raw coal gas from coal pyrolysis, comprising: an inlet / outlet heat exchanger 1, a detoxification tank 2, a deoxidizer 3, a dechlorination furnace 4, a scrubbing and humidifying tower 5, a gas preheater 6, a dechlorination tank 7, and a first adiabatic furnace 8. The inlet / outlet heat exchanger 1 has a first heat-releasing side and a first heat-absorbing side. The inlet of the first heat-absorbing side is used to introduce the preliminarily purified raw coal gas from coal pyrolysis. Optionally, the outlet of the first heat-releasing side is used to discharge the gas cooled by the inlet / outlet heat exchanger 1. The inlet of the detoxification tank 2 is connected to the outlet of the first heat-absorbing side. The inlet of the deoxidizer 3 is connected to... The outlet of the detoxification tank 2 is connected; the inlet of the dechlorination furnace 4 is connected to the outlet of the deoxygenation furnace 3; the washing and humidifying tower 5 is provided with a first inlet and a first outlet, and the first inlet of the washing and humidifying tower 5 is connected to the outlet of the dechlorination furnace 4; the gas preheater 6 has a second heat release side and a second heat absorption side, the inlet of the second heat absorption side is connected to the first outlet, and the outlet of the second heat release side is connected to the inlet of the first heat release side; the inlet of the dechlorination tank 7 is connected to the outlet of the second heat absorption side; the inlet of the first adiabatic furnace 8 is connected to the outlet of the dechlorination tank 7, and the outlet of the first adiabatic furnace 8 is connected to the inlet of the second heat release side.

[0040] The raw coal gas purification and conversion system of this invention can couple the purification and sulfur-resistant conversion heat during the impurity removal process of raw coal gas from coal pyrolysis. It analyzes the energy characteristics of oxygen hydrogenation, organochlorine, subsequent organosulfur and unsaturated hydrocarbon hydrogenation and adiabatic conversion processes. According to the energy requirements of hydrogenation detoxification and adiabatic conversion, the process energy is reasonably graded, coupled and matched. This includes the coupling process of sulfur-resistant conversion heat from the first adiabatic furnace 8 to hydrogenation deoxygenation in the deoxidation furnace 3 via inlet and outlet heat exchangers 1, hydrogenation deoxygenation heat from the deoxidation furnace 3 to hydrogenation dechlorination in the dechlorination furnace 4, and sulfur-resistant conversion heat from the first adiabatic furnace 8 to catalyst activation and hydrogenation desulfurization and unsaturated hydrocarbon hydrogenation in the hydrogenation furnace. The system of this invention removes impurity components in a step-by-step and graded manner based on the characteristics of each impurity through system optimization and energy coupling. In particular, it removes difficult-to-handle organic sulfur, organic chlorine, oxygen, and unsaturated hydrocarbons. It makes full use of the characteristic that these impurities require high-temperature hydrogenation for removal, and couples the heat of the reaction to achieve precise and effective removal of impurities. It solves the difficulties in heat grading and matching and segmented removal of impurities in the process of removing toxic substances such as oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons in the purification of raw coal gas. It overcomes the drawbacks of traditional hydrogenation processes that rely too much on high-quality superheated steam and electric heating, and achieves the multiple benefits of effective impurity purification, process optimization, energy grading coupling, and energy saving and environmental protection.

[0041] In this embodiment of the invention, the utilization of high-grade heat and low-grade heat achieves multi-stage coupling, resulting in high-efficiency utilization. It features a short process flow, full utilization of waste heat, reduced consumption of high-grade steam, rational energy utilization, simple operation, low investment costs, and low operation and maintenance costs. The energy coupling process makes the utilization of raw coal gas more rational, safe, stable, and energy-saving, with high feasibility, reasonable energy-stage coupling, and a simple process. Subsequently, the syngas, after adjusting the hydrogen-to-carbon ratio, undergoes desulfurization and decarbonization, and can be applied to the synthesis of methanol, ethanol, ethylene glycol, natural gas, ammonia, etc., as well as the production of H2 and other high-value effective gases (H2 and CO) in chemical industries. The syngas product has high quality, and the technology has strong scalability.

[0042] In some embodiments, the inlet and outlet heat exchanger 1 has a first heat release side and a first heat absorption side, and the inlet of the first heat absorption side is used to introduce pre-purified coal pyrolysis gas. Optionally, the inlet and outlet heat exchanger 1 is a shell-and-tube heat exchanger. The inlet and outlet heat exchanger 1 is provided with a first tube side and a first shell side. The first tube side forms a first heat absorption side and the first shell side forms a first heat release side. Optionally, the medium flowing in the first heat-absorbing side is pre-purified coal pyrolysis gas; the medium flowing in the first heat-releasing side is syngas, specifically, syngas flowing out from the first adiabatic furnace 8 or the first hydrogenation furnace 9 and cooled by the gas preheater 6. Optionally, the design temperature of the first tube side and the first shell side are both 330°C and the design pressure is both 4.5MPa; or, the design temperature of the first tube side and the first shell side are both 380°C and the design pressure is 4.5MPa; or, the design temperature of the first tube side is 330°C and the design pressure is 4.5MPa, and the design temperature of the first shell side is 400°C and the design pressure is 4.5MPa.

[0043] In some embodiments, an electric heater 15 is also included, the inlet of which is connected to the outlet of the first heat absorption side, and the outlet of which is connected to the inlet of the detoxification tank 2; optionally, the electric heater 15 is a start-up electric heater; optionally, the electric heater 15 is connected in series with the inlet and outlet heat exchanger 1.

[0044] In this embodiment of the invention, catalyst activation is required before startup. Before the catalytic reaction, depending on the characteristics of the catalyst, an electric heater is generally needed to heat the low-pressure (0.4 MPa) nitrogen gas to above the activation temperature. Only after the catalyst is activated can the gas be introduced for reaction. In the system of this invention, inlet and outlet heat exchangers 1 are used for heating. Alternatively, an electric heater 15 can be connected in series to ensure that the temperature of the syngas system remains stable at 260-280°C when the syngas system experiences temperature drops due to reduced heat released from the later catalyst conversion reaction, or when simple heat exchange cannot reach the appropriate activation temperature. This is to facilitate subsequent detoxification and deoxygenation steps.

[0045] In some embodiments, the detoxification tank 2 is provided with a detoxification tank 2 bed; the detoxification tank 2 is provided with a detoxification adsorbent, which includes at least one of ZnO, MgO, CaO, CaCO3, Na2CO3 or K2CO3; the design temperature of the detoxification tank 2 is 330℃ and the design pressure is 4.5MPa.

[0046] In some embodiments, the deoxidizer 3 is a single-stage deoxidizer; the deoxidizer 3 is provided with a first catalyst, which includes at least one of a Co-Mo catalyst or an Fe-Mo catalyst; the deoxidizer 3 is designed to have a temperature of 400°C and a pressure of 4.5 MPa.

[0047] In this embodiment of the invention, the deoxidation furnace 3 and the dechlorination furnace 4 are connected in sequence to complete the energy coupling of hydrodeoxidation and hydrodechlorination.

[0048] In some embodiments, the dechlorination furnace 4 is provided with a second catalyst, which includes at least one of Pd, Pt, Rh, Ni, Co, Cu or Fe; the dechlorination furnace 4 is designed to have a temperature of 400°C and a pressure of 4.5 MPa.

[0049] In some embodiments, in the first embodiment, the deoxidizer 3 and the dechlorination furnace 4 are independent devices; in the second embodiment, the deoxidizer 3 and the dechlorination furnace 4 are integrated into a furnace body, the furnace body having a first bed and a second bed, the first bed being located upstream of the second bed, the first bed being used to achieve the same effect as the deoxidizer 3, and the second bed being used to achieve the same effect as the dechlorination furnace 4.

[0050] In some embodiments, the washing and humidifying tower 5 is provided with a first inlet and a first outlet, and the first inlet of the washing and humidifying tower 5 is connected to the outlet of the dechlorination furnace 4; Optionally, the washing and humidifying tower 5 has an upper part and a lower part, with the upper part located downstream of the lower part. The lower part is used to initially remove inorganic chlorine through washing, while the upper part is used to humidify the gas by using humidifying steam. Optionally, the first inlet is located in the lower half, and the first outlet is located in the upper half; Optionally, the lower half is also provided with a second inlet and a second outlet. The second inlet is used to connect to a water source, and the second outlet is used to discharge condensate. The upper half is also provided with a third inlet. The third inlet is used to introduce humidifying steam. Optionally, the humidifying steam includes at least one of saturated steam and superheated steam. In a specific embodiment, the washing and humidifying tower 5 is provided with a first inlet, a first outlet, a second inlet, a second outlet, and a third inlet. The first inlet of the washing and humidifying tower 5 is connected to the outlet of the dechlorination furnace 4, the second inlet is used to connect to a water source, the second outlet is used to discharge condensate, and the third inlet is used to connect to humidifying steam. The washing and humidifying tower 5 has an upper half and a lower half. Optionally, the first inlet, the second inlet, and the second outlet are located in the lower half of the washing and humidifying tower 5. Optionally, the first inlet is located at the bottom of the tower. In dechlorination furnace 4, the organic chlorine is hydrogenated to complete the conversion of organic chlorine to inorganic chlorine. HCl can be carried out of the system with the condensate through water washing. Therefore, the raw coal gas after organic chlorine hydrogenation enters the lower half of the washing and humidification tower 5, where the HCl component in the gas is removed by washing, thus completing the removal of inorganic chlorine from the system. The water source may include at least one of the following: low-temperature condensate from the subsequent ammonia washing tower 14, water separated by the separator 16, and cold boiler feedwater (e.g., not higher than 40°C); optionally, the second inlet may have one, two, or more inlets. For example, it may be a single inlet where one or more water sources converge and enter the second inlet for washing; or it may be two or more inlets on the same horizontal plane, without interfering with each other; the number of the second inlets may be comprehensively considered during the engineering design stage based on the amount and distribution effect of the low-temperature condensate and cold boiler feedwater. Optionally, the first outlet and the third inlet are located in the upper part of the scrubbing and humidifying tower 5. For example, the first outlet can be located at the top of the scrubbing and humidifying tower 5, and the gas enters from the bottom of the tower and exits from the top. The upper part of the washing and humidifying tower 5 is replenished with humidifying steam. According to the required water-to-gas ratio (e.g., 0.2~0.5), for example, the conversion reaction depth meets the requirements of downstream methanol synthesis (H2 / CO: ~2.00, modulus: 2.00~2.10). The humidified gas at the top outlet of the washing and humidifying tower 5 is sent to the next process. The condensate in the bottom of the washing and humidifying tower 5 is treated and sent to the upstream low-temperature water washing section for recycling and then sent to the wastewater treatment plant. Optionally, the design temperature of the washing and humidifying tower 5 is 400℃ and the design pressure is 4.5MPa.

[0051] In some embodiments, the gas preheater 6 has a second heat-releasing side and a second heat-absorbing side. The inlet of the second heat-absorbing side is connected to the first outlet, the outlet of the second heat-absorbing side is connected to the inlet of the dechlorination tank 7, and the inlet of the second heat-releasing side is connected to the outlet of the first adiabatic furnace 8 or the outlet of the first hydrogenation furnace 9; the outlet of the second heat-releasing side is connected to the inlet of the first heat-releasing side. Optionally, the gas preheater 6 adopts a shell-and-tube heat exchanger, which has a second tube side and a second shell side. The second tube side forms the second heat absorption side, and the second shell side forms the second heat release side. Optionally, the circulating medium in the second heat-absorbing side is a humidifying gas, and the circulating medium in the second heat-releasing side is a syngas, specifically, the syngas flowing out of the first adiabatic furnace 8 or the first hydrogenation furnace 9; Optionally, the design temperature of the second tube side is 300℃ and the design pressure is 4.5MPa; the design temperature of the second shell side is 450℃ and the design pressure is 4.5MPa.

[0052] In this embodiment of the invention, the washed and humidified raw coal gas (humidified gas) is heated in the coal gas preheater 6 by the synthesis gas from the outlet of the first adiabatic furnace 8 or the first hydrogenation furnace 9 to the activation temperature (220~260°C) of the catalyst in the first adiabatic furnace 8.

[0053] In some embodiments, the dechlorination tank 7 is provided with a dechlorination adsorbent. Optionally, the dechlorination adsorbent includes at least one of CaO, MgO, CuO, ZnO, Na2CO3, NaHCO3, Ca(OH)2, or Mg(OH)2. The gas enters the dechlorination tank 7 for protective adsorption and removal of inorganic chlorine. The dechlorination adsorbent acts as a protective agent to further remove inorganic chlorine, preventing the residual chlorine from causing irreversible poisoning to the downstream conversion catalyst if the washing effect is poor.

[0054] In some embodiments, the first adiabatic furnace 8 is provided with a third catalyst (conversion catalyst), which includes a Co-Mo-based sulfur-resistant conversion catalyst. Raw coal gas enters the first adiabatic furnace 8 and undergoes a partial conversion reaction. The heat of the syngas after the first adiabatic conversion reaches the activation temperature of the hydrogenation reaction, thus achieving coupling between the heat of the adiabatic conversion and the heat of the hydrogenation reaction.

[0055] In some embodiments, the system further includes a first hydrogenation furnace 9, the inlet of which is connected to the outlet of a first adiabatic furnace 8, and the outlet of the first hydrogenation furnace 9 is connected to the inlet of a second heat release side. Optionally, in the first embodiment, the first adiabatic furnace 8 and the first hydrogenation furnace 9 are independent devices; in the second embodiment, the first adiabatic furnace 8 and the first hydrogenation furnace 9 are integrated into a furnace body, the furnace body having a third bed and a fourth bed, the third bed being located upstream of the fourth bed, the third bed being used to achieve the same effect as the first adiabatic furnace 8, and the fourth bed being used to achieve the same effect as the first hydrogenation furnace 9. Optionally, the first hydrogenation furnace 9 is provided with a fourth catalyst, which may include a Co-Mo based hydrogenation catalyst. The gas after the first adiabatic conversion undergoes a first hydrogenation reaction to convert organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively, thereby removing organic sulfur and unsaturated hydrocarbons.

[0056] In some embodiments, the system further includes a humidifier 10, a second adiabatic furnace 11, and a second hydrogenation furnace 12. The humidifier 10 is provided with a first gas inlet, a first gas outlet and a humidifying steam inlet. The first gas inlet is connected to the outlet on the first heat release side. The humidifying steam inlet is used to introduce humidifying steam. Optionally, the humidifying steam includes saturated steam. The inlet of the second adiabatic furnace 11 is connected to the first gas outlet; optionally, the second adiabatic furnace 11 is provided with a fifth catalyst, which includes a Co-Mo-based sulfur-resistant shift catalyst. The inlet of the second hydrogenation furnace 12 is connected to the outlet of the second adiabatic furnace 11. Optionally, the outlet of the second hydrogenation furnace 12 is used to discharge gas. Optionally, the second hydrogenation furnace 12 is provided with a sixth catalyst, which includes a Co-Mo hydrogenation catalyst. Optionally, since the two-stage adiabatic conversion reaction process basically achieves the effective conversion of organic sulfur and unsaturated hydrocarbons, the second hydrogenation furnace 12 is set after the second adiabatic furnace 11 mainly to play the role of protective hydrogenation. The second hydrogenation furnace 12 can also be placed after the first adiabatic furnace 8, with the same function as the first hydrogenation furnace 9. In some embodiments, a waste heat recovery heat exchanger 13 is also included, which has a third heat release side and a third heat absorption side. The inlet of the third heat release side is connected to the outlet of the first heat release side, or the inlet of the third heat release side is connected to the outlet of the second hydrogenation furnace 12. Optionally, the third heat-absorbing side is connected to a cold source, and there are no special restrictions on the selection of the cold source in this embodiment of the invention; Optionally, the waste heat recovery heat exchanger 13 is a shell-and-tube heat exchanger with a third tube side and a third shell side. The third tube side forms the third heat release side, and the third shell side forms the third heat absorption side. Optionally, the circulating medium on the third exothermic side is syngas, specifically syngas cooled by the inlet and outlet heat exchanger 1 or gas exiting the second hydrogenation furnace 12. The circulating medium on the third absorbent side is a heat recovery medium. This invention does not have a special limitation on the heat recovery medium; it can be any medium to be heated or a cooling medium. For example, at least one of the following can form the waste heat recovery heat exchanger 13: a low-pressure waste heat boiler, the reboiler of the MDEA decarbonization tower, or a water source. Specifically, for example, the syngas cooled by the inlet and outlet heat exchanger 1 is used to provide heat energy to the reboiler of the MDEA decarbonization tower and / or preheat the demineralized water. The gas exiting the second hydrogenation furnace 12 is cooled by the low-pressure waste heat boiler, the reboiler of the decarbonization tower, and the preheated demineralized water. Optionally, the design parameters for the third tube side and the third shell side depend on the operating conditions.

[0057] In this embodiment of the invention, the heat from the adiabatic shift reaction undergoes three-stage coupling and two-stage recovery, including coupling with the hydrogenation reaction, the humidified raw coal gas temperature rise, and the inlet and outlet raw coal gas heat. After recovering high-grade heat energy (e.g., approximately 360°C → 160°C) through the gas preheater 6 and the inlet and outlet heat exchangers 1, the gas further recovers low-grade heat energy (e.g., approximately 160°C → 40°C) through the waste heat recovery heat exchanger 13. The gas entering the waste heat recovery heat exchanger 13 can recover the remaining low-grade heat energy through at least one of the following: a low-pressure waste heat boiler, the MDEA decarbonization tower reboiler, and preheated demineralized water. The shifted waste heat provides heat energy to the MDEA decarbonization tower reboiler and preheats the demineralized water. The preheated demineralized water is then sent to the deaerator, reducing the consumption of low-pressure steam in the deaerator and effectively and rationally utilizing the shifted low-grade heat energy, avoiding the energy waste associated with a large-scale circulating water cooling process.

[0058] In some embodiments, the system also includes an ammonia scrubbing tower 14, which has a fourth inlet, a fourth outlet, a fifth inlet, and a fifth outlet. The fourth inlet is connected to the outlet on the third exothermic side, the fourth outlet is used to discharge syngas, the fifth inlet is used to connect to a water source, and the fifth outlet is used to discharge low-temperature condensate. Optionally, the fifth outlet is connected to the second inlet and serves as a water source for washing and dechlorination. Optionally, the fourth inlet is located in the lower half of the ammonia washing tower 14, the fourth outlet is located at the top of the ammonia washing tower 14, the fifth inlet is located in the upper half of the ammonia washing tower 14, and the fifth outlet is located at the bottom of the ammonia washing tower 14. Optionally, the ammonia washing tower 14 is designed to have a temperature of 70°C and a pressure of 4.3 MPa. Optionally, there are no special restrictions on the water source. For example, the water source may include low-temperature cold boiler water (boiler feedwater). Optionally, the temperature of the water source may be controlled at ≤40℃, as excessively high temperatures will lead to a poorer ammonia washing effect.

[0059] In this embodiment of the invention, the gas after sufficient heat recovery is sent to the ammonia washing tower 14 to remove any NH3 that may be present in the raw gas by water washing, ensuring that the ammonia content in the gas sent from the top of the tower to the desulfurization and decarbonization meets the standard (<2ppm).

[0060] In some embodiments, a condensate pump 17 is also included, the inlet of which is connected to a fifth outlet and the outlet of which is connected to a second inlet, for sending the low-temperature condensate from the ammonia washing tower 14 into the washing and humidifying tower 5 for washing.

[0061] In this embodiment of the invention, the low-temperature condensate from the bottom of the ammonia washing tower 14 is pressurized by the condensate pump 17 (for example, 4.0 MPa, which can be determined according to the relative position of the equipment and the system pressure) and then sent to the washing and humidifying tower 5 for chlorination. After chlorination, the condensate is sent to the low-temperature water washing section for recycling.

[0062] In some embodiments, a preliminary purification unit is further included, which includes an electrostatic precipitator, a low-temperature water washing device, and a compression device. The inlet of the electrostatic precipitator is used to introduce coal pyrolysis raw gas. The low-temperature water washing device is provided with a sixth inlet, a sixth outlet, a seventh inlet, and a seventh outlet. The sixth inlet is connected to the outlet of the electrostatic precipitator, the sixth outlet is connected to the inlet of the compression device, and the seventh inlet is used to connect to a water source. Optionally, the seventh inlet is connected to the second outlet, and the seventh outlet is used to discharge liquid. The inlet of the compression device is connected to the sixth outlet, and the outlet of the compression device is connected to the inlet of the first heat absorption side or to the eighth inlet of the separator 16. Optionally, the inlet of the electrostatic precipitator is connected to the outlet of the coal pyrolysis unit; Optionally, it also includes a gas holder, the inlet of which is connected to the outlet of the electrostatic precipitator, and the outlet of which is connected to the sixth inlet of the cryogenic water washing device. Optionally, the compression device includes a first compression device, a removal device, and a second compression device. The inlet of the first compression device is the inlet of the compression device, the outlet of the first compression device is connected to the inlet of the removal device, the outlet of the removal device is connected to the inlet of the second compression device, and the outlet of the second compression device is the outlet of the compression device.

[0063] In some embodiments, a separator 16 is also included. The separator 16 has an eighth inlet, an eighth outlet and a ninth outlet. The eighth inlet is connected to the outlet of the compression device, the eighth outlet is connected to the inlet of the first heat absorption side, and the ninth outlet is used to discharge water. Optionally, the ninth outlet is connected to the second inlet and can be used as a water source to be fed into the washing and humidification tower 5 for washing and dechlorination. The separator 16 is used to separate liquid water from the raw coal gas.

[0064] In this embodiment of the invention, the separator 16 is used to prevent the imported raw coal gas from containing saturated water, which, if not treated in time, could easily lead to catalyst pulverization if introduced into the catalyst bed.

[0065] In some embodiments, a desulfurization and decarbonization device is also included, the inlet of which is connected to the fourth outlet of the ammonia washing tower 14; the desulfurization and decarbonization device is used to remove inorganic sulfur (H2S) and carbon dioxide (CO2) from the syngas (gas) to provide purified syngas products to downstream units; optionally, the desulfurization and decarbonization device adopts MDEA desulfurization and decarbonization, for example, an MDEA decarbonization tower; the outlet of the desulfurization and decarbonization device discharges syngas, and optionally, the outlet of the desulfurization and decarbonization device is connected to the downstream product synthesis unit.

[0066] This invention discloses a method for purifying and converting raw coal gas from coal pyrolysis using a system based on this invention. The method includes the following steps: (1) The raw coal gas from coal pyrolysis is heated after preliminary purification, and then detoxified by a detoxifying adsorbent; after detoxification, it undergoes a hydrogenation deoxygenation reaction to remove oxygen; after hydrogenation deoxygenation, it undergoes an organic chlorine hydrogenation reaction to convert organic chlorine into inorganic chlorine, and then the inorganic chlorine is initially removed by washing, and then humidified by humidifying steam to obtain humidified gas. (2) The humidifying gas is heated and then the inorganic chlorine is further removed by protective adsorption dechlorination through a dechlorination adsorbent; after dechlorination, the first adiabatic transformation reaction is carried out; the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas.

[0067] In this embodiment of the invention, the method of coupling purification and heat conversion of raw coal gas from coal pyrolysis can achieve the coupling of purification and sulfur-resistant heat conversion during the removal of impurities from raw coal gas from coal pyrolysis. It analyzes the energy characteristics of oxygen hydrogenation, organochlorine, subsequent organosulfur and unsaturated hydrocarbon hydrogenation and adiabatic conversion processes. According to the energy requirements of hydrogenation detoxification and adiabatic conversion, the process energy is reasonably graded, coupled and matched. This includes the coupling process of using sulfur-resistant heat conversion to heat the initially purified raw coal gas for detoxification and hydrogenation deoxygenation, using hydrogenation deoxygenation heat for hydrogenation dechlorination, and using sulfur-resistant heat conversion to activate the catalyst and perform hydrogenation reaction desulfurization and unsaturated hydrocarbon coupling. The method of this invention removes impurity components in a step-by-step and graded manner based on the characteristics of each impurity through process optimization and energy coupling. In particular, it removes difficult-to-handle organic sulfur, organic chlorine, oxygen, and unsaturated hydrocarbons, making full use of their requirement for high-temperature hydrogenation removal. By coupling the heat of the conversion reaction, it achieves precise and effective removal of impurities. This solves the difficulties in heat grading and segmented impurity removal in the process of removing toxic substances such as oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons from raw coal gas. It overcomes the drawbacks of traditional hydrogenation processes that rely excessively on high-quality superheated steam and electric heating, achieving the multiple benefits of effective impurity purification, process optimization, energy grading coupling, and energy saving and environmental protection.

[0068] In this embodiment of the invention, for organic chlorines and organic sulfur compounds (especially thiophene) that are difficult to remove from raw coal gas at low temperatures via hydrogenation, the removal of organic impurities is achieved by utilizing the heat of hydrogenation deoxygenation and shift reaction to increase the hydrogenation temperature. This is accompanied by the adsorption and removal of inorganic chlorines and subsequent hydrogenation removal of organic sulfur and unsaturated hydrocarbons. The inorganic sulfur can be sent to downstream desulfurization and decarbonization units for final removal. Specifically, the raw coal gas purification and shift method first heats the raw coal gas with syngas. The raw coal gas undergoes detoxification to remove impurities containing lone pairs of electrons, such as HCN, and then undergoes hydrogenation deoxygenation. The temperature rise from oxygen hydrogenation ensures the activity of organic chlorine hydrogenation, allowing for the high-temperature hydrogenation removal of organic chlorines that have a diffusive poisoning effect on the third catalyst (shift catalyst). Most of the inorganic chlorine in the raw coal gas is removed by washing, and chlorine that poisons the shift catalyst is further removed by an inorganic chlorine adsorbent. Subsequently, the first adiabatic shift reaction is carried out. Through the heat coupling of the first adiabatic shift, the high-temperature syngas is further hydrogenated to convert organic sulfur into inorganic sulfur under the action of a hydrogenation catalyst, and the hydrogenation removal of unsaturated hydrocarbons is achieved, thus completing the entire process of hydrogenation detoxification and shift reaction heat coupling.

[0069] In this embodiment of the invention, the hydrogen-to-carbon ratio of raw coal gas is flexibly adjusted through heat coupling processes such as changing the reaction heat and detoxification hydrogenation. The syngas, after desulfurization and decarbonization, is then sent to downstream product production units. This process is highly feasible, has reasonable energy stage coupling, and is simple. This process can be extended to various chemical production processes that require high-value effective gases (H2 and CO), such as methanol synthesis, ethanol synthesis, ethylene glycol synthesis, natural gas synthesis, ammonia synthesis, and H2 production. It helps to overcome problems such as energy waste, catalyst poisoning, and frequent system shutdowns. The obtained syngas product has high purity and high quality. The method of this invention has strong scalability and far-reaching practical significance.

[0070] In some embodiments, in step (1), the present invention does not have special restrictions on the composition and source of coal pyrolysis raw gas, and can be applied to different coal pyrolysis raw gas. For example, the coal pyrolysis raw gas can be from coal pyrolysis raw gas under different processes. The system and method can be extended to the purification route of coal pyrolysis raw gas of various pyrolysis furnace types. For example, the coal pyrolysis raw gas can be from coal pyrolysis raw gas in a pure oxygen environment. In a specific embodiment, the composition of coal pyrolysis raw gas is shown in Table 1. Coal pyrolysis raw gas includes CO, H2, CH4, and also includes at least one of CO2, N2, O2, organic chlorine, inorganic chlorine, organic sulfur, inorganic sulfur, unsaturated hydrocarbons, tar, dust, NH3, HCN and others (e.g., H2O).

[0071] In some embodiments, in step (1), the raw coal gas from coal pyrolysis is preliminarily purified to obtain preliminarily purified raw coal gas. Optionally, preliminary purification is carried out in a preliminary purification unit; the preliminary purification unit includes an electrostatic precipitator, a low-temperature water washing device, and a compression device; optionally, it also includes a gas holder; optionally, the compression device includes a first compression device, an impurity removal device, and a second compression device. Optionally, the preliminary purification includes: electrostatic precipitator to remove tar and dust from the raw coal gas from coal pyrolysis, followed by water washing to further remove tar and dust, and then compression to obtain the preliminary purified raw coal gas; optionally, the electrostatic precipitator is carried out in an electrostatic precipitator device; the water washing is carried out in a low-temperature water washing device; and the compression is carried out in a compression device. Optionally, the preliminary purification also includes a gas storage step, in which the raw coal pyrolysis gas is subjected to electrostatic precipitator to remove tar and dust, then stored, and then washed with water to further remove tar and dust; optionally, the gas storage is carried out in a gas holder, optionally a dry gas holder. Optionally, the compression after water washing includes: primary compression after water washing, followed by impurity removal (removing organic matter, such as benzene, naphthalene and some organic impurities), and secondary compression to obtain preliminarily purified raw coal gas; optionally, primary compression is carried out in the first compression device, impurity removal is carried out in the impurity removal device, and secondary compression is carried out in the second compression device. Optionally, the temperature of the water wash is generally required to not exceed 40°C; the water for the water wash comes from the condensate of the washing and humidifying tower 5. Optionally, the pressure of the gas after primary compression is 1.5~2.0 MPa; Optionally, the present invention does not have any special limitations on impurity removal, and impurity removal can be carried out using common adsorption techniques, such as at least one of temperature-switching adsorption (TSA adsorption) and microcrystalline adsorption; the content of benzene and naphthalene at the outlet after impurity removal is ≤1 mg / Nm³, respectively. 3 ; Optionally, the pressure of the gas after secondary compression is 4.0~4.5MPa (which can be adjusted appropriately according to the downstream product requirements); the secondary compression adopts centrifugal compression; Optionally, the present invention does not impose any special limitations on the composition of the pre-purified raw coal gas. For example, the pre-purified raw coal gas includes at least one of the following: impurities containing lone pairs of electrons, oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons. In a specific embodiment, the pre-purified raw coal gas includes impurities containing lone pairs of electrons, oxygen, organic chlorine, organic sulfur, and unsaturated hydrocarbons. In a specific embodiment, the pre-purified raw coal gas includes, by mole fraction: CO 34.00%, H2 33.00%, CO2 18.50%, N2 4.04%, CH4 8.00%, O2 0.40%, H2O saturated, and organic chlorine ≤10 mg / Nm³. 3 Organic sulfur ≤100mg / Nm 3 Unsaturated hydrocarbons ≤0.238% and others.

[0072] In this embodiment of the invention, the raw coal gas exiting the coal pyrolysis unit contains impurities such as tar and dust, which significantly impacts the stable operation of downstream gas holders and the compression process. Electrostatic precipitator removes residual tar and dust from the raw coal gas. The gas is then sent to the gas holder for storage, ensuring stable and continuous operation of the chemical production. A low-temperature water washing step is added to further protectively remove tar and dust from the raw coal gas, while also removing ammonia to some extent, minimizing the impact on the downstream compression unit and reducing the load on subsequent purification and shift conversion sections. The coarsely purified raw coal gas is then sent to the impurity removal process after primary compression. To ensure efficient compression while allowing the raw coal gas to pass smoothly through the impurity removal process, the primary compression outlet pressure is set at 1.5~2.0 MPa. The main purpose of the impurity removal process is to remove benzene, naphthalene, and some organic impurities from the raw coal gas. Technologies such as TSA adsorption or similar selective adsorption techniques can be used to ensure that the benzene and naphthalene content at the outlet is ≤1 mg / Nm³. 3 After impurity removal, the raw coal gas undergoes secondary compression to increase its pressure to a suitable and economical range (e.g., 4.0~4.5MPa) before being sent to the hydrodetoxification and shift conversion processes to ensure the stable operation of downstream units. The pressurized raw coal gas still contains toxic substances such as oxygen, organic chlorine, inorganic chlorine, organic sulfur, and unsaturated hydrocarbons, which can affect the activity of the sulfur-resistant shift catalyst or the energy consumption of downstream units. This is a key reason why most raw coal gas projects cannot operate stably for extended periods. Therefore, it is necessary to consider removing these impurities in the shift conversion stage (e.g., ensuring O2 ≤ 5ppm, total sulfur ≤ 0.1ppm (after desulfurization and decarbonization), total chlorine ≤ 10ppb, and unsaturated hydrocarbons ≤ 0.1%), and to adjust the hydrogen-to-carbon ratio of the outlet syngas through the shift reaction to meet the needs of downstream chemical products such as methanol, ethanol, ethylene glycol, natural gas, ammonia, and H2. The raw coal gas from coal pyrolysis undergoes a reasonable step-by-step purification process, including: tar removal, washing to remove ash and ammonia, impurity removal (benzene, naphthalene, tar, small molecule organic matter, etc.), hydrogenation of large molecule organic impurities, shift reaction, and hydrogenation of unsaturated hydrocarbons.

[0073] In some embodiments, in step (1), the present invention does not impose special restrictions on the temperature and pressure of the pre-purified raw coal gas, which can be adjusted as needed, or the required temperature can be achieved through subsequent heating. In a specific embodiment, the temperature of the pre-purified raw coal gas is 90~120℃, optionally 100℃, and the pressure is 4.0~4.5MPa.

[0074] In some embodiments, in step (1), the pre-purified raw coal gas is heated to a temperature of 260~280°C, specifically, for example, 260°C, 270°C, 280°C; optionally, the heating is carried out in the inlet and outlet heat exchanger 1 and / or the electric heater 15.

[0075] In this embodiment of the invention, the temperature of the raw coal gas after being heated by high-temperature syngas is 260~280℃, which meets the activation temperature of the oxygen hydrogenation catalyst.

[0076] In some embodiments, in step (1), detoxification is performed using a detoxifying adsorbent; Optionally, detoxification is carried out in detoxification tank 2; Optionally, detoxification includes removing at least one of impurities containing lone pairs of electrons and inorganic chlorine. Optionally, impurities containing lone pairs of electrons include at least one of HCN and SO2. Optionally, the detoxifying adsorbent includes at least one of ZnO, MgO, CaO, CaCO3, Na2CO3 or K2CO3; Optionally, the detoxification temperature is 260~280℃, specifically, for example, 260℃, 270℃, 280℃; generally, it is required to be more than 30℃ higher than the syngas dew point temperature to prevent irreversible damage to the detoxification adsorbent.

[0077] In this embodiment of the invention, compounds containing unsaturated electron pairs such as HCN and inorganic chlorine can be removed by detoxifying adsorbents.

[0078] In some embodiments, in step (1), after detoxification, a hydrogenation deoxygenation reaction is performed to remove oxygen; Optionally, the hydrodeoxygenation reaction is carried out in deoxygenation furnace 3; Optionally, the hydrodeoxygenation reaction is carried out under the catalysis of a first catalyst; the first catalyst includes at least one of a Co-Mo catalyst or an Fe-Mo catalyst; optionally, the content of the active component in the first catalyst is controlled to be at least one of MoO3 10~15wt%, CoO 2~5wt%, and Fe2O3 2~5wt%; optionally, the first catalyst is provided with a modifying agent; it is provided with 0.1%-2wt% of the modifying agent, which includes at least one of K, Na, P, Cu, and Zn elements; the mass percentage is the mass percentage relative to the support. Optionally, the initial temperature of the hydrodeoxygenation reaction is 260~280℃ (e.g., 260℃, 270℃, 280℃), and the outlet temperature (temperature after reaction) is 330~380℃ (e.g., 330℃, 350℃, 360℃, 380℃) depending on the oxygen concentration.

[0079] In this embodiment of the invention, the activation temperature of the first catalyst for oxygen hydrogenation is 260~280℃, therefore, preheating is required. This can be achieved through superheated steam combined with electric heating and gas-to-gas heat exchange. In this invention, the raw coal gas is heated by changing and / or hydrogenating the syngas, and electric heating is provided as needed. Based on the composition of the raw coal gas, the temperature rise of the hydrodeoxygenation reaction needs to be greater than 80℃, and the outlet temperature can reach about 350℃, which can achieve a good hydrogenation effect of organochlorines. Therefore, it is suitable to use the heat from the hydrodeoxygenation reaction to couple the organochlorine hydrogenation reaction. The outlet temperature of the deoxygenator 3 fluctuates with the oxygen content, and the outlet temperature is generally controlled at about 350℃, for example, 330~380℃ (the outlet temperature can also be adjusted by the aforementioned heating steps) to ensure that the temperature of the syngas entering the dechlorination furnace 4 is suitable, ensuring the conversion rate of organochlorine hydrogenation, completely converting organochlorines into inorganic chlorines, and the temperature rise during the organochlorine hydrogenation process is almost negligible.

[0080] In some embodiments, in step (1), after hydrogenation and deoxygenation, an organochlorine hydrogenation reaction is carried out to convert the organochlorine into inorganic chlorine; Optionally, the organochlorine hydrogenation reaction is carried out in dechlorination furnace 4; Optionally, the organochlorine hydrogenation reaction is carried out under the catalysis of a second catalyst, which includes at least one of Pd, Pt, Rh, Ni, Co, Cu or Fe. The ratio and content of the active component can be flexibly adjusted according to the type and content of the organochlorine. For example, the content of the active component is 0.1%-5wt%. Optionally, a modifying agent is provided, which is 0.5%-5wt% of the modifying agent, including at least one of K, Na, La, Ce, Mo or W. Optionally, the temperature for hydrogenating organochlorines is not lower than 350°C; the temperature rise during the hydrogenation process of organochlorines is almost negligible.

[0081] In some embodiments, in step (1), inorganic chlorine is initially removed by washing; Optionally, washing is carried out in a washing humidification tower 5, specifically in the lower half of the washing humidification tower 5; Optionally, the washing includes water washing, i.e., dechlorination is achieved through water washing. The water temperature is generally controlled to not exceed 40°C, as low temperature is beneficial for dechlorination. The washing water source includes at least one of the following: the low-temperature condensate reused from the ammonia washing tower 14, the supplementary boiler feedwater, and the liquid water separated by the separator 16. Optionally, 100,000 Nm³ 3 / h of syngas corresponds to 12~15t / h of washing water to ensure sufficient washing of inorganic chlorine. In this embodiment of the invention, chlorine washing can be performed using the low-temperature condensate after ammonia washing mixed with an appropriate amount of low-temperature boiler feedwater.

[0082] In some embodiments, in step (1), the gas is then humidified by humidifying steam to obtain a humidifying gas; Optionally, humidification is carried out in a washing humidification tower 5, specifically in the upper part of the washing humidification tower 5; Optionally, the humidifying steam includes at least one of saturated steam or superheated steam; Optionally, humidification is achieved by changing the water-to-gas ratio using humidifying steam. The water-to-gas ratio refers to the ratio of the molar content of water to the molar content of the remaining gas. The water-to-gas ratio can be flexibly adjusted according to the required transformation depth of the downstream product. Optionally, the water-to-gas ratio of the humidifying gas is 0.2 to 0.7, expressed as a mole fraction, specifically, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7. Optionally, the quality of the humidifying steam can be flexibly adjusted according to the project's configuration. For example, in a specific embodiment of the superheated steam of this invention, the superheated steam grade can be 9.8 MPa at 540°C, ensuring that the superheated steam boundary pressure is not lower than 4.2 MPa and the temperature is not lower than 400°C; or, 4.5 MPa saturated gas can be used. Products such as methanol, LNG, and synthetic ammonia have different requirements for the depth of the conversion reaction, different water-to-gas ratios required by the conversion furnace, and different qualities of the supplementary steam. The steam grade should be flexibly adjusted according to the specific project configuration. It is not necessary to use 9.8 MPa 540°C superheated steam and 4.5 MPa saturated steam. It should be comprehensively considered based on factors such as the reaction system pressure, heat balance, and water-to-gas ratio. Optionally, the temperature of the humidifying gas is 160~200℃ (e.g., 160℃, 165℃, 170℃, 180℃, 190℃, 200℃), and there are no special restrictions on the pressure. For example, the pressure can be 3.8~3.9MPa (e.g., 3.8MPa, 3.85MPa, 3.9MPa).

[0083] In this embodiment of the invention, the syngas is humidified by high-pressure humidifying steam to achieve the water-to-gas ratio required for downstream conversion. The quality of the humidifying steam is flexibly adjusted according to the project's supporting conditions, and the water-to-gas ratio of the humidifying gas should also be flexibly adjusted according to the downstream product's requirements for conversion depth.

[0084] In some embodiments, in step (2), the humidifying gas is heated; Optionally, heating is carried out in the gas preheater 6; Optionally, the temperature of the heated humidifying gas is 220~260℃, specifically, for example, 220℃, 230℃, 240℃, 250℃, 260℃.

[0085] In some embodiments, in step (2), inorganic chlorine is further removed by protective adsorption dechlorination using a dechlorination adsorbent; Optionally, protective adsorption dechlorination is carried out in dechlorination tank 7; optionally, dechlorination tank 7 includes a dechlorination adsorbent protective bed. Optionally, the dechlorination adsorbent includes at least one of CaO, MgO, CuO, ZnO, Na2CO3, NaHCO3, Ca(OH)2 or Mg(OH)2; Optionally, the temperature for protective adsorption dechlorination is 220~260℃ (e.g., 220℃, 230℃, 240℃, 250℃, 260℃), and there are no special restrictions on the pressure, for example, the pressure can be 3.8~3.9MPa (e.g., 3.8MPa, 3.85MPa, 3.9MPa).

[0086] In some embodiments, in step (2), a first adiabatic transformation reaction is performed after dechlorination; Optionally, the first adiabatic transformation reaction takes place in the first adiabatic furnace 8; Optionally, the initial activation temperature of the first adiabatic shift reaction is 220~260℃ (e.g., 220℃, 230℃, 240℃, 250℃, 260℃), and the activation temperature can be flexibly adjusted according to the catalyst activity. Optionally, the outlet (syngas) temperature of the first adiabatic shift reaction is 350~400℃ (e.g., 350℃, 360℃, 380℃, 390℃, 400℃), which can be varied according to the catalyst activity; alternatively, the outlet temperature is the temperature after the reaction. Optionally, the first adiabatic shift reaction is carried out under the catalysis of a third catalyst (shift catalyst), which includes a Co-Mo based sulfur-resistant shift catalyst; optionally, the main active precursor of the Co-Mo based sulfur-resistant shift catalyst is MoO3, with a content of 8~15wt%, and the co-active precursor is CoO, with a content of 1~3wt%, and it is also equipped with at least one of the promoters containing elements such as K, Na, and P; optionally, the activation temperature of the third catalyst is 220~260℃, and the activation temperature is flexibly adjusted according to the catalyst activity; Optionally, there is no special limitation on the depth of the first adiabatic shift reaction. It can be flexibly adjusted according to the type of downstream product (the requirement for hydrogen-to-carbon ratio) to synthesize different chemical products. For example, when used to produce methanol, the H2 / CO ratio of the synthesis gas after the shift outlet adjustment should be about 2.00, and the corresponding methanol synthesis modulus is 2.00~2.10.

[0087] In this embodiment of the invention, the syngas temperature during isothermal conversion is low, resulting in low quality and a large amount of low-pressure steam as a byproduct. This invention employs adiabatic conversion, fully utilizing the high-quality heat energy of the conversion reaction. Furthermore, the raw coal gas has a high H2S content, which meets the sulfur content requirements of the sulfur-resistant conversion catalyst. Therefore, a Co-Mo based sulfur-resistant conversion catalyst is considered for use.

[0088] In this process, impurities from low-temperature carbonization can be removed in the upstream purification stage. Unsaturated hydrocarbons, organic sulfur compounds, organic chlorine compounds, and harmful toxins (such as O2, NH3, SO2, and HCN) in the raw coal gas are removed during the purification and shift conversion stages. The removal of unsaturated hydrocarbons, organic sulfur compounds, organic chlorine compounds, and O2 is generally achieved through effective conversion via high-temperature hydrogenation before removal. NH3 and HCN, rich in unsaturated electron pairs, can be selectively removed using adsorbents. Therefore, the key challenge in purification and shift conversion lies in the heat coupling during impurity removal. It is crucial to rationally utilize the high-grade heat energy from the shift conversion process to provide energy, avoiding excessive reliance on high-quality heat energy sources such as superheated steam and electricity, thereby reducing energy consumption during the purification process.

[0089] In this embodiment of the invention, the wide-temperature sulfur-resistant catalyst has a relatively broad activity temperature range (200~480℃), and an activation temperature of not less than 230℃ is generally suitable. Raw coal gas enters the first adiabatic furnace 8 and undergoes a partial shift reaction (~350℃), completing the coupling of heat from the adiabatic shift reaction and the hydrogenation reaction. The shift depth can be flexibly adjusted according to the shift requirements through various means such as the configuration of the first adiabatic furnace 8 and the water-to-gas ratio, to meet the shift depth requirements of different downstream chemicals.

[0090] In some embodiments, in step (2), the gas after the first adiabatic transformation undergoes a first hydrogenation reaction to convert organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively. The resulting gas is cooled sequentially by humidifying gas and pre-purified raw coal gas to obtain syngas. Optionally, the first hydrogenation reaction is carried out in the first hydrogenation furnace 9; Optionally, the temperature of the first hydrogenation reaction is 350~380℃ (e.g., 350℃, 360℃, 370℃, 380℃). Optionally, the first hydrogenation reaction is carried out under the catalysis of a fourth catalyst, which includes a Co-Mo based hydrogenation catalyst. Optionally, depending on the catalytic requirements, the main active precursor of the Co-Mo based hydrogenation catalyst is MoO3 with a content of 10~18wt%, the co-active precursor is CoO with a content of 1~4wt%, and it is also equipped with at least one of the promoters containing elements such as K, Na, and P and / or at least one of the promoters containing elements such as Ni and Pd. Optionally, the composition of the syngas after the first hydrogenation reaction is not specifically limited and can be adjusted by flexibly changing the depth of the reaction according to the needs of downstream products. In a specific embodiment, for example, the syngas after the hydrogenation reaction includes, in mole fraction, 17.44% CO, 37.67% H2, 28.03% CO2, 3.40% N2, 6.72% CH4, 0.00% O2, 0.76% H2S, 0.60% saturated hydrocarbons and others. Optionally, the obtained gas is cooled by the humidifying gas, and the temperature after cooling is 270~340℃, specifically, for example, 270℃, 290℃, 295℃, 310℃, 320℃, 330℃, 340℃; And / or, after the raw coal gas has been preliminarily purified and cooled, the temperature after cooling is 140~220℃, specifically, for example, 140℃, 150℃, 160℃, 170℃, 180℃, 200℃, 220℃; And / or, the obtained gas is cooled sequentially by humidified gas and pre-purified raw coal gas, and then cooled again; optionally, the temperature after the second cooling is 40~60℃, specifically, for example, 40℃, 50℃, 60℃; optionally, the second cooling is carried out in the waste heat recovery heat exchanger 13, and optionally, at least one of the MDEA decarbonization tower reboiler and preheated demineralized water is used for cooling. And / or, the resulting gas is cooled sequentially by humidifying gas and preliminarily purified raw coal gas, then humidified again by humidifying steam, and then undergoes a second adiabatic shift reaction; optionally, the gas is cooled again after the second adiabatic shift reaction.

[0091] In this embodiment of the invention, some organic sulfur and unsaturated hydrocarbons also undergo hydrogenation during the adiabatic conversion process. The high-temperature syngas after conversion undergoes further hydrogenation of organic sulfur and unsaturated hydrocarbons, converting them into inorganic sulfur and saturated hydrocarbons. This helps to reduce the impact of organic sulfur and unsaturated hydrocarbons on downstream purification and protects the stable operation of downstream desulfurization and decarbonization. The high reactivity temperature range for organic sulfur hydrogenation and unsaturated hydrocarbon hydrogenation generally requires a temperature not lower than 350°C to achieve complete conversion. Organic sulfur hydrogenation and unsaturated hydrocarbon hydrogenation can be coupled through a first adiabatic conversion. At the same time, the hydrogenated gas can also heat and humidify the gas and preheat the hydrogenation deoxygenation feed gas (preliminarily purified raw coal gas). This avoids the low-grade, low-pressure steam produced as a byproduct of isothermal conversion and improves the efficient utilization of conversion heat energy, achieving staged coupled utilization of energy.

[0092] In this embodiment of the invention, the heat from the thermal shift reaction undergoes three-stage coupling and two-stage recovery. For example, it is coupled with the heat from the hydrogenation reaction, humidification gas, and pre-purified raw coal gas. After three-stage coupling—using sulfur-resistant shift heat for hydrodeoxygenation, hydrodeoxygenation heat for hydrodechlorination, and sulfur-resistant shift heat for catalyst activation, hydrodesulfurization, and unsaturated hydrocarbon hydrogenation—the high-grade heat energy (e.g., 360→160℃) is recovered via the coal gas preheater 6 and inlet / outlet heat exchangers 1. The residual heat from the low-temperature syngas (~160℃) can still further recover low-grade heat energy (160→40℃). The syngas undergoes a third cooling process, mainly including the MDEA decarbonization tower reboiler and demineralized water preheating, to recover the remaining low-grade heat energy, avoiding energy waste from a large-scale circulating water cooling process.

[0093] In some embodiments, the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas; Optionally, after the gas undergoing the first adiabatic transformation is cooled by the humidifying gas, the temperature after cooling is 340~360℃, specifically, for example, 340℃, 350℃, 360℃; Optionally, after the raw coal gas has been preliminarily purified, the temperature after cooling is 240~260℃, specifically, for example, 240℃, 250℃, 260℃; Optionally, the gas after the first adiabatic shift is cooled sequentially by humidifying gas and preliminarily purified raw coal gas, then humidified again by humidifying steam, and then undergoes a second adiabatic shift reaction; the gas after the second adiabatic shift undergoes a second hydrogenation reaction to convert organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively, to obtain syngas; the syngas after the shift reaction can also be called shift gas. Optionally, the humidifying steam includes saturated steam; Optionally, the temperature of the gas after rehumidification is 220~240℃, specifically, for example, 220℃, 230℃, 240℃; Optionally, the outlet temperature (temperature after reaction) of the second adiabatic conversion reaction is 270~300℃, specifically, for example, 270℃, 280℃, 290℃, 300℃; Optionally, the second adiabatic shift reaction is carried out under the catalysis of a fifth catalyst, which includes a Co-Mo-based sulfur-resistant shift catalyst. Optionally, the temperature of the second hydrogenation reaction is 270~300℃, specifically, for example, 270℃, 280℃, 290℃, 300℃; Optionally, the second hydrogenation reaction is carried out under the catalysis of a sixth catalyst, which includes a Co-Mo based hydrogenation catalyst; Optionally, the gas obtained after the second hydrogenation reaction is cooled again. Optionally, the temperature after cooling is 40~60℃, specifically, for example, 40℃, 50℃, 60℃. Optionally, the cooling is carried out in the waste heat recovery heat exchanger 13. Optionally, at least one of the following is used for cooling: low-pressure waste heat boiler, MDEA decarbonization tower reboiler, and preheated demineralized water. In a specific embodiment, for example, the low-pressure waste heat boiler, MDEA decarbonization tower reboiler, and preheated demineralized water are used for cooling in sequence.

[0094] In this embodiment of the invention, a second adiabatic shift reaction is performed after the first adiabatic shift reaction, which can purify and shift the gas to obtain syngas for ammonia synthesis. In this invention's method for coupling the purification and shift heat of raw coal gas from coal pyrolysis, the temperature, water-to-gas ratio, and other parameters can be flexibly adjusted according to the shift requirements of the target product.

[0095] In some embodiments, the gas is cooled and then subjected to ammonia washing to obtain syngas. Optionally, the ammonia washing process is carried out in ammonia washing tower 14; Optionally, after the obtained gas is cooled sequentially by humidifying gas and preliminarily purified raw coal gas, the obtained gas is cooled again and then subjected to ammonia washing treatment to remove ammonia. Optionally, the gas obtained after the second adiabatic shift reaction is cooled again and then subjected to ammonia washing. Optionally, the gas obtained after the second hydrogenation reaction is cooled again and then subjected to ammonia washing. Optionally, the ammonia washing process includes water washing; optionally, the water comes from boiler water, for example, low-temperature cold boiler water (boiler feedwater), and the water temperature does not exceed 40°C; Optionally, the ammonia content in the syngas after ammonia washing treatment meets the standard (<2ppm). Optionally, the ammonia washing process removes ammonia and generates low-temperature condensate. The low-temperature condensate is pressurized by the condensate pump 17 (4.0 MPa, depending on the relative position of the equipment and the system pressure) and then sent to the washing and humidification tower 5 for chlorine washing. After that, it is sent to the low-temperature water washing device for recycling.

[0096] In this embodiment of the invention, the syngas after sufficient heat recovery is sent to the ammonia washing tower 14 to remove any NH3 that may be present in the raw gas by low-temperature cold boiler water washing, ensuring that the ammonia content in the syngas sent from the top of the tower for desulfurization and decarbonization meets the standard (<2ppm). The low-temperature condensate in the tower bottom is pressurized (4.0MPa) by the condensate pump 17 and then sent to the washing and humidification tower 5 for chlorination washing, and then sent together to the low-temperature water washing section for recycling.

[0097] In some embodiments, the syngas after ammonia washing is desulfurized and decarbonized; Optionally, desulfurization and decarbonization are carried out in a desulfurization and decarbonization unit; Optionally, desulfurization and decarbonization shall employ at least one of MDEA decarbonization, low-temperature methanol washing, or similar decarbonization technologies; Optionally, the H2 / CO ratio of the syngas after desulfurization and decarbonization can be flexibly adjusted according to the type of downstream product. For example, if it is used to produce methanol, the H2 / CO ratio of the shift gas after adjustment at the shift outlet should be about 2.00, and the corresponding methanol synthesis modulus is 2.00~2.10.

[0098] In this embodiment of the invention, H2S and CO2 can be removed through desulfurization and decarbonization processes, while other unsaturated hydrocarbons can be removed after separation in downstream units. MDEA, low-temperature methanol washing, or similar desulfurization and decarbonization technologies can be selected for CO2 removal to meet the requirements of downstream product units. Subsequently, the qualified synthesis gas with a suitable hydrogen-to-carbon ratio (e.g., H2 / CO: ~2.00, modulus: 2.00~2.10) after purification and decarbonization is sent to downstream product units (e.g., methanol synthesis units, where refined methanol is obtained after methanol distillation).

[0099] In some embodiments, the resulting gas contains O2 ≤ 5 ppm, total sulfur (after desulfurization and decarbonization) ≤ 0.1 ppm, total chlorine ≤ 10 ppb, and unsaturated hydrocarbons ≤ 0.1%.

[0100] In some embodiments, the raw coal gas from coal pyrolysis is purified and transformed, and the H2 / CO ratio of the syngas product can be flexibly adjusted according to product requirements; the syngas can be used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

[0101] In some embodiments, such as Figure 1 and Figure 2 As shown, the method for purifying and coupling the heat of coal pyrolysis raw gas includes the following steps: (1) After preliminary purification, the raw coal gas from coal pyrolysis is heated by inlet and outlet heat exchangers 1, and then detoxified by the detoxifying adsorbent in detoxification tank 2; after detoxification, it is fed into deoxygenation furnace 3 to remove oxygen by hydrogenation deoxygenation reaction; after hydrogenation deoxygenation, it is fed into dechlorination furnace 4 to carry out organic chlorine hydrogenation reaction to convert organic chlorine into inorganic chlorine, and then fed into the lower half of washing and humidification tower 5 to remove inorganic chlorine by washing, and then fed into the upper half of washing and humidification tower 5 to humidify by humidifying steam to obtain humidified gas; (2) The humidifying gas is heated by the gas preheater 6 and then introduced into the dechlorination tank 7 for protective adsorption and dechlorination by the dechlorination adsorbent to further remove inorganic chlorine. After dechlorination is complete, it enters the first adiabatic furnace 8 for the first adiabatic conversion reaction. Optionally, the gas after the first adiabatic conversion enters the first hydrogenation furnace 9 to carry out the first hydrogenation reaction, converting organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively. The resulting gas is cooled by humidified gas in the gas preheater 6, and then cooled by pre-purified raw coal gas in the inlet and outlet heat exchangers 1 to obtain syngas. Alternatively, the gas after the first adiabatic transformation is cooled by humidified gas in the gas preheater 6, and then cooled by the pre-purified raw coal gas in the inlet and outlet heat exchangers 1 to obtain syngas.

[0102] In some embodiments, in step (1), before being heated by the inlet and outlet heat exchanger 1, the raw coal gas from coal pyrolysis is first pre-purified, and the pre-purified raw coal gas is then heated; the pre-purification includes: the raw coal gas from coal pyrolysis is electro-coke removed by an electro-coke removal device, and then further washed by a low-temperature water washing device to remove tar and dust, and then compressed by a compression device after water washing. Optionally, the preliminary purification also includes a gas storage step, in which the raw coal gas is electrostatically precipitated to remove tar and dust, then passed into a gas holder for gas storage, and then further washed with a low-temperature water washing device to remove tar and dust. After washing, a first compression device is used for primary compression, followed by impurity removal using a removal device, and then a second compression device is used for secondary compression. Optionally, the gas holder includes a dry gas holder.

[0103] A synthesis gas according to an embodiment of the present invention is obtained by means of coal pyrolysis of raw coal gas using the method of the present invention.

[0104] An application of syngas in this invention is described, wherein the syngas is used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

[0105] In this embodiment of the invention, the H2 / CO ratio of the syngas can be flexibly adjusted according to the type of downstream products. After purification and conversion, the syngas with a suitable hydrogen-to-carbon ratio is sent downstream to prepare downstream products, such as methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

[0106] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0107] Example 1 Based on the composition of raw coal gas specified in Table 1 above, and taking the coal pyrolysis raw coal gas to methanol production process as an example, the system and method of the present invention are further described in detail below: like Figure 1 As shown, the overall process flow for producing methanol from raw coal gas via coal pyrolysis is as follows: (a) Preliminary purification process of raw coal gas from coal pyrolysis: (1) The raw coal gas from the coal pyrolysis unit outlet contains impurities such as tar and dust, which have a significant impact on the stable operation of the downstream gas holder and compression process. The residual tar and dust are first removed by an electrostatic precipitator.

[0108] (2) Considering factors such as the continuous operation cycle of the coal pyrolysis unit, in order to ensure the stable and continuous operation of chemical production, a dry gas holder is set up to store the raw coal gas after electrostatic precipitator.

[0109] (3) Then, a protective low-temperature water washing device is used to further prevent the raw coal gas from carrying a large amount of tar and dust. At the same time, the ammonia in the raw coal gas can be pre-washed to minimize the impact of tar and dust on the downstream compression unit and the impact of ammonia on the shift adsorbent and other catalysts.

[0110] (4) After the crudely purified raw coal gas is compressed in the first stage, it is sent to the impurity removal device in the impurity removal process. In order to save compression power while ensuring that the raw coal gas passes through the impurity removal process naturally and smoothly, the outlet pressure of the first stage compression is 1.5~2.0MPa.

[0111] (5) The main purpose of the impurity removal process is to remove benzene, naphthalene, and some organic impurities from the raw coal gas. Technologies that can be used include TSA adsorption (temperature-switching adsorption) or similar selective adsorption technologies (such as microcrystalline adsorption technology) to ensure that the content of benzene and naphthalene at the outlet is ≤1 mg / Nm³. 3 .

[0112] (6) Subsequently, the raw coal gas is subjected to two-stage centrifugal compression to increase the system pressure to a suitable and economical pressure range (4.0~4.5MPa), and the preliminarily purified raw coal gas from coal pyrolysis is sent to the subsequent hydrogenation detoxification and conversion processes.

[0113] (II) Hydrogenation detoxification and conversion process: The toxic substances such as oxygen, organic chlorine, inorganic chlorine, organic sulfur, and unsaturated hydrocarbons in the pre-purified raw coal pyrolysis gas can affect the activity of the sulfur-resistant shift catalyst and the energy consumption of downstream units. This is a key reason why the purification and shifting processes in general raw coal gas utilization projects cannot operate stably for extended periods. Therefore, it is necessary to remove harmful impurities. The impurity content after removal in this invention meets the following requirements: O2 ≤ 5 ppm, total sulfur ≤ 0.1 ppm (after desulfurization and decarbonization), total chlorine ≤ 10 ppb, and unsaturated hydrocarbons ≤ 0.1%.

[0114] Based on the composition of the raw coal gas, the temperature rise of the hydrodeoxygenation reaction needs to be greater than 80°C, and the outlet temperature can reach about 350°C, which can achieve a good hydrogenation effect of organochlorines. Therefore, it is suitable to use the heat of the hydrodeoxygenation reaction to couple the hydrogenation reaction of organochlorines.

[0115] Wide-temperature sulfur-resistant shift catalysts have a broad activity temperature range (200~480℃), with an activation temperature generally not lower than 230℃ being suitable. Organic sulfur hydrogenation and unsaturated hydrocarbon hydrogenation have a high activity temperature range of not lower than 350℃, achieving complete conversion. By coupling organic sulfur hydrogenation and unsaturated hydrocarbon hydrogenation through adiabatic shift, and simultaneously preheating and humidifying the gas and preliminarily purified coal pyrolysis gas, this avoids the drawbacks of low-grade, low-pressure steam as a byproduct of isothermal shift and achieves efficient utilization of the heat from the shift reaction, realizing the staged coupling utilization of energy.

[0116] After a three-stage coupling process—using the heat from sulfur-resistant shift conversion to supply hydrodeoxygenation, the heat from hydrodeoxygenation to supply organochlorine hydrodechlorination, and the heat from sulfur-resistant shift conversion to supply hydrodesulfurization and unsaturated hydrocarbon hydrogenation—the waste heat (~160℃) from the low-temperature syngas can still be recovered through the bottom of the MDEA decarbonization tower and the low-temperature demineralized water, avoiding energy waste from the large-scale circulating water cooling process.

[0117] Secondly, compounds containing unsaturated electron pairs, such as HCN and SO2, as well as inorganic chlorine, can be removed by adsorption using a detoxification catalyst. H2S and CO2 can be removed through desulfurization and decarbonization processes. Other unsaturated hydrocarbons can be removed after separation in downstream units, thus achieving both effective removal of toxic substances and efficient energy utilization.

[0118] (III) Desulfurization, decarbonization and methanol synthesis process: Since the CO2 content in the synthesis gas is suitable (~30%), MDEA and low-temperature methanol washing or similar desulfurization and decarbonization technologies can be selected to remove CO2. Then, the synthesis gas with a suitable hydrogen-to-carbon ratio (H2 / CO: ~2.00, modulus: 2.00~2.10) is sent to the downstream methanol synthesis unit, and after methanol distillation, refined methanol product is obtained.

[0119] Example 2 like Figure 2 As shown, the purification and conversion method for raw coal gas from coal pyrolysis to methanol production includes the following steps: 1) Preheating process: The raw coal gas from upstream, after preliminary purification, is heated to 100℃ and pressurized to 4.0MPa. The main components of the pre-purified raw coal gas, by mole fraction, are: CO 34.00%, H2 33.00%, CO2 18.50%, N2 4.04%, CH4 8.00%, O2 0.40%, H2O saturated, and organic chlorine ≤10mg / Nm³. 3 Organic sulfur ≤100mg / Nm 3 Unsaturated hydrocarbons ≤0.238% and others.

[0120] After preliminary purification, the raw coal gas is heated to 260~280℃ by the syngas through the inlet and outlet heat exchanger 1. An electric heater is connected in series in the system to ensure that the temperature of the heated raw coal gas is stable at 260~280℃, thus completing the heat coupling between the syngas and the preliminary purified raw coal gas.

[0121] Among them, the inlet and outlet heat exchanger 1 is a tube-side heat exchanger. The tube side carries the pre-purified raw coal gas, and the shell side carries the syngas. The design temperature of both the tube side and the shell side is 330℃, and the design pressure of both sides is 4.5MPa.

[0122] 2) Hydrogenation detoxification process: The heated raw coal gas enters detoxification tank 2 (protective detoxification tank bed) where impurities containing lone pairs of electrons, such as HCN and SO2, are removed by the detoxification adsorbent. The design temperature of detoxification tank 2 is 330℃ and the design pressure is 4.5MPa.

[0123] 3) Subsequently, the hydrogenation and deoxygenation reaction occurs in a deoxidation furnace. The outlet temperature of deoxidation furnace 3 fluctuates with the oxygen content. The outlet temperature is generally controlled at around 350℃ to ensure that the temperature of the syngas entering dechlorination furnace 4 is appropriate and to ensure the conversion rate of organochlorine hydrogenation.

[0124] 4) The gas enters the dechlorination furnace 4 to carry out the organic chlorine hydrogenation (hydrodechlorination) reaction, completely converting the organic chlorine into inorganic chlorine. The temperature rise during the organic chlorine hydrogenation process is almost negligible. The deoxidation furnace 3 and the dechlorination furnace 4 have the same design parameters: a design temperature of 400℃ and a design pressure of 4.5MPa.

[0125] 5) Humidification and temperature control process: The raw coal gas after the organic chlorine hydrogenation reaction enters the lower half of the washing and humidification tower 5. It is thoroughly washed by the low-temperature condensate from the circulating ammonia washing tower and the low-temperature boiler feedwater (40℃) to remove the inorganic chlorine (HCl component) in the gas. The HCl can be removed by water washing and carried out of the system with the condensate, thus completing the removal of chlorine in the system.

[0126] The upper part of the washing and humidification tower 5 is supplemented with superheated steam (9.8MPa, 540℃) to make up the water-to-gas ratio (0.2~0.5) required for the conversion, so that the depth of the subsequent first adiabatic conversion reaction meets the requirements of downstream methanol synthesis (H2 / CO: ~2.00, modulus: 2.00~2.10).

[0127] The humidified gas (wet raw coal gas) from the top outlet of the humidification tower 5 continues to be sent to the next process (~165℃), and the condensate in the tower bottom is treated and then sent to the upstream low-temperature water washing section for recycling before being sent to the wastewater treatment plant. The design temperature of the humidification tower 5 is 400℃ and the design pressure is 4.5MPa.

[0128] 6) Adiabatic shift reaction heat coupling process: The humidified gas is further heated in the gas preheater 6 to the activation temperature (~230℃) of the shift catalyst in the first adiabatic furnace 8 after passing through the syngas outlet of the first hydrogenation furnace 9. Then it enters the protective inorganic chlorine dechlorination tank 7 to remove any remaining inorganic chlorine in the system and avoid irreversible poisoning of the shift catalyst.

[0129] The gas preheater has a tube side that carries humidifying gas (wet raw coal gas) and a shell side that carries syngas. The tube side is designed to have a temperature of 300℃ and a pressure of 4.5MPa, while the shell side is designed to have a temperature of 450℃ and a pressure of 4.5MPa.

[0130] 7) Subsequently, the raw coal gas enters the first adiabatic furnace 8 and undergoes a partial adiabatic conversion reaction (first adiabatic conversion reaction) (~350℃), completing the coupling of adiabatic conversion heat and hydrogenation reaction heat.

[0131] The conversion depth can be flexibly adjusted through various means such as bypassing the first adiabatic furnace 8 and the water-gas ratio to ensure that the depth of the outlet syngas meets the requirements of downstream methanol synthesis.

[0132] 8) The converted high-temperature synthesis gas enters the first hydrogenation furnace 9 for further hydrogenation reactions of organic sulfur and unsaturated hydrocarbons, ensuring the operational stability and consumption of downstream desulfurization and decarbonization.

[0133] 9) The heat from the first adiabatic transformation reaction is coupled in three stages and recovered in two stages, as mentioned above, with the heat from the hydrogenation reaction, the humidified gas, and the pre-purified raw coal gas. The heat is then successively recovered through the coal gas preheater 6 and the inlet and outlet heat exchangers 1 to recover high-grade heat energy (360℃→160℃).

[0134] 10) Waste heat recovery and ammonia washing process: Subsequently, the syngas enters the waste heat recovery heat exchanger 13 to continue to recover low-grade heat energy (160℃→40℃), mainly through the reboiler of the MDEA decarbonization tower and the preheating of demineralized water to recover the remaining low-grade heat energy.

[0135] In the waste heat recovery heat exchanger, the tube side carries syngas, while the shell side carries the heat recovery medium. The design parameters depend on the operating conditions.

[0136] 11) The syngas (40℃) after sufficient heat recovery is sent to the ammonia washing tower 14 to be washed by low-temperature cold boiler water (40℃) to remove any NH3 that may be present in the gas, ensuring that the ammonia content in the syngas sent to the top of the tower for desulfurization and decarbonization meets the standard (<2ppm). The low-temperature condensate in the tower bottom is pressurized (4.0MPa) by the condensate pump 17 and then sent to the washing and humidification tower 5 for chlorination. After chlorination, it is sent to the low-temperature water washing section for recycling.

[0137] Among them, the ammonia washing tower 14 is designed with a temperature of 70℃ and a pressure of 4.3MPa.

[0138] 12) The gas is sent to the desulfurization and decarbonization unit for desulfurization and decarbonization. After the impurities are removed, the content of the synthesis gas of the present invention meets the following requirements: O2≤5ppm, total sulfur≤0.1ppm, total chlorine≤10ppb, and unsaturated hydrocarbons≤0.1%.

[0139] Subsequently, the synthesis gas with a suitable hydrogen-to-carbon ratio (H2 / CO: ~2.00, modulus: 2.00~2.10) is sent to the downstream methanol synthesis unit, where it is purified into methanol product after methanol distillation.

[0140] Comparative Example 1 To better illustrate the advantages of the adiabatic heat exchange multi-stage coupling method used in this invention, Example 2 (methanol product route) is used as an example. A comparison is made between Example 2 (using adiabatic heat exchange) and Comparative Example 1 (using isothermal heat exchange). The process of Comparative Example 1 (using isothermal heat exchange) is as follows: Figure 3 As shown.

[0141] For the methanol technology route, the main difference between Example 2, which uses adiabatic conversion, and Comparative Example 1, which uses isothermal conversion, is as follows: 1. The heat from the isothermal shift reaction in the isothermal furnace is recovered through the steam drum, producing 1.3MPa low-pressure saturated steam as a byproduct, resulting in low-quality energy utilization. 2. The syngas at the hydrogenation furnace inlet needs to be heated by a heater through 9.8MPa 540℃ superheated steam. Compared with the heat coupling of adiabatic transformation in Example 2, this increases the equipment investment of the heater and the consumption of superheated steam.

[0142] From these two perspectives, based on the "Standard for Energy Consumption Calculation in Petrochemical Design" (GB / T 50441-2016) and the "General Rules for Comprehensive Energy Consumption Calculation" (GB / T 2589-2020), the isothermal process consumes 18.3 t / h more superheated steam at 9.8 MPa 540℃ during the humidification and heating processes compared to the adiabatic process. It also produces 9.6 t / h more saturated steam at 1.3 MPa and consumes 9.8 t / h more medium-pressure boiler feedwater. Therefore, the overall comprehensive energy consumption is higher than that of the adiabatic process. Using the adiabatic process scheme of this invention saves the equivalent of 1583.5 kgce / h of standard coal. Specifically, based on a cost of 200 yuan / t for 9.8 MPa 540℃ superheated steam, 120 yuan / t for 1.3 MPa saturated steam, and 8 yuan / t for boiler feedwater, the adiabatic process scheme of this invention can save 20.691 million yuan in operating costs annually. Furthermore, the adiabatic coupling process of this invention avoids the equipment investment required for the downstream heater of the isothermal furnace (tube side: S32168 material, shell side: A335M material), reducing one-time equipment and facility investment by approximately 3 million yuan. In summary, the adiabatic heat exchange coupling process adopted in this invention has significant advantages and promising application prospects.

[0143] Example 3 like Figure 4 The process shown illustrates a purification and conversion method for raw coal gas from coal pyrolysis used in a raw coal gas to liquefied natural gas (LNG) project. The method is the same as in Example 2, except that: In step 1), the design temperature of the shell side of the inlet and outlet heat exchangers is 380℃ and the design pressure is 4.5MPa.

[0144] In step 5), the upper part of the washing and humidifying tower 5 is supplemented with superheated steam (9.8MPa, 540℃) to meet the water-gas ratio required for the conversion (0.2~0.5, high conversion depth, the actual water-gas ratio is higher than that of the methanol product route), so that the depth of the subsequent first adiabatic conversion reaction meets the requirements of downstream methane synthesis (H2 / CO: ≥3.00).

[0145] The humidified gas (wet raw coal gas) at the top outlet of the washing and humidifying tower 5 is sent to the next process (~190℃, high conversion depth, the actual amount of superheated steam added is higher than that of the methanol product route).

[0146] In step 7), the raw coal gas enters the first adiabatic furnace 8 and undergoes a partial adiabatic conversion reaction (~370℃, the conversion depth is higher than that of the methanol product route).

[0147] In step 9), the heat from the first adiabatic transformation reaction undergoes three-stage coupling and two-stage recovery, as described above, with heat coupling with the hydrogenation reaction, wet raw coal gas, and inlet and outlet raw coal gas, and high-grade heat energy (380℃→220℃) is recovered through the coal gas preheater 6 and the inlet and outlet heat exchanger 1.

[0148] Example 4 like Figure 5 The process shown adjusts the downstream product to synthetic ammonia, and then extends to downstream chemicals such as urea. The purification and conversion method of coal pyrolysis raw gas includes the following steps: 1) Preheating process: The raw coal gas from upstream, after preliminary purification, is at a temperature of 100℃ and a pressure of 4.0MPa. Its main components, by mole fraction, are: CO 34.00%, H2 33.00%, CO2 18.50%, N2 4.04%, CH4 8.00%, O2 0.40%, H2O saturated state, and organic chlorine ≤10mg / Nm³. 3 Organic sulfur ≤100mg / Nm 3 Unsaturated hydrocarbons ≤0.238% and others.

[0149] After preliminary purification, the raw coal gas is heated to 260~280℃ by the syngas through the inlet and outlet heat exchanger 1. An electric heater is connected in series in the system to ensure that the temperature of the heated raw coal gas is stable at 260~280℃, thus completing the heat coupling between the syngas and the preliminary purified raw coal gas.

[0150] Among them, the inlet and outlet heat exchanger 1 is a tube-side heat exchanger. The tube side carries the pre-purified raw coal gas, and the shell side carries the syngas. The tube side design temperature is 330℃ and the design pressure is 4.5MPa, and the shell side design temperature is 400℃ and the design pressure is 4.5MPa.

[0151] 2) Hydrogenation detoxification process: The heated raw coal gas enters detoxification tank 2 (protective detoxification tank bed) where impurities containing lone pairs of electrons, such as HCN and SO2, are removed by the detoxification adsorbent. The design temperature of detoxification tank 2 is 330℃ and the design pressure is 4.5MPa.

[0152] 3) Subsequently, the hydrogenation and deoxygenation reaction occurs in a deoxidation furnace. The outlet temperature of deoxidation furnace 3 fluctuates with the oxygen content. The outlet temperature is generally controlled at around 350℃ to ensure that the temperature of the syngas entering dechlorination furnace 4 is appropriate and to ensure the conversion rate of organochlorine hydrogenation.

[0153] 4) The gas enters the dechlorination furnace 4 to carry out the organic chlorine hydrogenation (hydrodechlorination) reaction, completely converting the organic chlorine into inorganic chlorine. The temperature rise during the organic chlorine hydrogenation process is almost negligible. As shown above, the energy coupling of hydrodeoxygenation and organic chlorine hydrogenation is completed. The design parameters of the deoxygenation furnace 3 and the dechlorination furnace 4 are kept consistent, with a design temperature of 400℃ and a design pressure of 4.5MPa.

[0154] 5) Humidification and temperature control process: The raw coal gas after the organic chlorine hydrogenation reaction enters the lower half of the washing and humidification tower 5. It is thoroughly washed by the low-temperature condensate from the circulating ammonia washing tower and the low-temperature boiler feedwater (40℃) to remove the inorganic chlorine (HCl component) in the gas. The HCl can be removed by water washing and carried out of the system with the condensate, thus completing the removal of chlorine in the system.

[0155] The upper part of the washing and humidification tower 5 uses superheated steam (9.8MPa, 540℃) to supplement the water-gas ratio required for the conversion (0.4~0.7, the first adiabatic conversion depth is high, and the actual water-gas ratio is higher than that of the methanol and LNG product routes), so that the dry basis depth of the subsequent first adiabatic conversion reaction is 6~8%.

[0156] The humidified gas from the top outlet of the humidification and washing tower 5 continues to be sent to the next process (~190℃, high conversion depth). The condensate in the tower bottom is treated and then sent to the upstream low-temperature water washing section for recycling before being sent to the wastewater treatment plant. The design temperature of the humidification and washing tower 5 is 400℃, and the design pressure is 4.5MPa.

[0157] 6) Adiabatic shift reaction heat coupling process: The humidified gas is further heated in the gas preheater 6 to the activation temperature (~230℃) of the shift catalyst in the first adiabatic furnace 8 after passing through the syngas outlet of the first adiabatic furnace 8. Then it enters the protective inorganic chlorine dechlorination tank 7 to remove any remaining inorganic chlorine in the system and avoid irreversible poisoning of the shift catalyst.

[0158] The gas preheater has a tube side that carries humidifying gas and a shell side that carries syngas. The tube side is designed to have a temperature of 300℃ and a pressure of 4.5MPa, while the shell side is designed to have a temperature of 450℃ and a pressure of 4.5MPa.

[0159] 7) Subsequently, the raw coal gas enters the first adiabatic furnace 8 to undergo the first adiabatic conversion reaction (partial adiabatic conversion reaction) (~400℃, the conversion depth is higher than that of the methanol and LNG product routes, and the dry basis depth is 6~8%). The conversion depth can be flexibly adjusted by various means such as bypassing the first adiabatic furnace 8 and the water-gas ratio to ensure that the depth of the outlet syngas meets the requirements of the downstream second adiabatic conversion reaction.

[0160] 8) The high-temperature synthesis gas after conversion passes through the gas preheater 6 and the inlet and outlet heat exchangers 1 to recover the high-temperature reaction heat of the first adiabatic conversion reaction in sequence. The heat from the first adiabatic transformation reaction undergoes three-stage coupling and two-stage recovery, such as the coupling with the heat from the humidifying gas, the pre-purified raw coal gas, and the hydrogenation reaction, and recovers high-grade heat energy (400→250℃) through the coal gas preheater 6 and the inlet and outlet heat exchangers 1.

[0161] 9) After secondary humidification by humidifier 10, it enters the second adiabatic furnace 11 for the second adiabatic conversion reaction, thereby ensuring that the dry basis depth of the outlet CO meets the requirements of the ammonia synthesis unit (dry basis depth 0.5~1.0%).

[0162] 10) Subsequently, the high-temperature syngas enters the second hydrogenation furnace 12 for further hydrogenation reactions of organic sulfur and unsaturated hydrocarbons, ensuring the operational stability and consumption of downstream desulfurization and decarbonization. Unlike the methanol and LNG product routes, the heat from the second adiabatic shift reaction is utilized to ensure the reactivity of the second hydrogenation furnace 12.

[0163] 11) Waste heat recovery and ammonia washing process: Subsequently, the syngas enters the waste heat recovery heat exchanger 13 to continue recovering low-grade heat energy (290℃→40℃). Unlike the methanol and LNG routes, a new low-pressure waste heat boiler is added to recover heat and produce 0.5~1.2MPa saturated steam as a byproduct (290℃→165℃, the syngas outlet temperature is flexibly adjusted according to the grade of the byproduct steam). The remaining low-grade heat energy is further recovered through the MDEA decarbonization tower reboiler and preheated demineralized water (165℃→40℃).

[0164] In the waste heat recovery heat exchanger, the tube side carries syngas, while the shell side carries the heat recovery medium. The design parameters depend on the operating conditions.

[0165] 12) The syngas (40℃) after sufficient heat recovery is sent to the ammonia washing tower 14 to be washed by low-temperature cold boiler water (40℃) to remove any NH3 that may be present in the gas, ensuring that the ammonia content in the syngas sent to the top of the tower for desulfurization and decarbonization meets the standard (<2ppm). The low-temperature condensate in the tower bottom is pressurized (4.0MPa) by the condensate pump 17 and then sent to the washing and humidification tower 5 for chlorination. After chlorination, it is sent to the low-temperature water washing section for recycling.

[0166] Among them, the ammonia washing tower 14 is designed with a temperature of 70℃ and a pressure of 4.3MPa.

[0167] 13) The gas is sent to the desulfurization and decarbonization unit for desulfurization and decarbonization. After the impurities are removed, the content of the synthesis gas of the present invention meets the following requirements: O2≤5ppm, total sulfur≤0.1ppm, total chlorine≤10ppb, and unsaturated hydrocarbons≤0.1%.

[0168] The gas is then sent to the downstream ammonia synthesis unit to synthesize ammonia products.

[0169] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0170] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0171] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0172] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A system for coupling the purification and heat conversion of raw coal gas from coal pyrolysis, characterized in that, include: An inlet and outlet heat exchanger has a first heat release side and a first heat absorption side, and the inlet of the first heat absorption side is used to introduce pre-purified coal pyrolysis gas. A detoxification tank, wherein the inlet of the detoxification tank is connected to the outlet of the first heat absorption side; A deoxidizer furnace, wherein the inlet of the deoxidizer furnace is connected to the outlet of the detoxification tank; A dechlorination furnace, wherein the inlet of the dechlorination furnace is connected to the outlet of the deoxygenation furnace; A washing and humidifying tower is provided with a first inlet and a first outlet, and the first inlet of the washing and humidifying tower is connected to the outlet of the dechlorination furnace; A gas preheater, the gas preheater having a second heat release side and a second heat absorption side, the inlet of the second heat absorption side being connected to the first outlet, and the outlet of the second heat release side being connected to the inlet of the first heat release side. A dechlorination tank, the inlet of which is connected to the outlet of the second heat absorption side; The first adiabatic furnace has its inlet connected to the outlet of the dechlorination tank, and its outlet is connected to the inlet of the second heat release side.

2. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 1, characterized in that, It also includes an electric heater, the inlet of which is connected to the outlet of the first heat absorption side, and the outlet of which is connected to the inlet of the detoxification tank; And / or, the washing and humidifying tower has an upper part and a lower part, the upper part being located downstream of the lower part; The first inlet is located in the lower half, and the first outlet is located in the upper half; The lower part is also provided with a second inlet and a second outlet. The second inlet is used to connect to a water source, and the second outlet is used to discharge condensate. The upper part is also provided with a third inlet, which is used to introduce humidifying steam.

3. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 1 or 2, characterized in that, It also includes a first hydrogenation furnace, the inlet of which is connected to the outlet of the first adiabatic furnace, and the outlet of the first hydrogenation furnace is connected to the inlet of the second heat release side. And / or, also includes a humidifier, a second insulated furnace, and a second hydrogenation furnace, The humidifier is provided with a first gas inlet, a first gas outlet and a humidifying steam inlet. The first gas inlet is connected to the outlet on the first heat-releasing side, and the humidifying steam inlet is used to introduce humidifying steam. The inlet of the second adiabatic furnace is connected to the outlet of the first gas. The inlet of the second hydrogenation furnace is connected to the outlet of the second adiabatic furnace.

4. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 3, characterized in that, It also includes a waste heat recovery heat exchanger, which has a third heat release side and a third heat absorption side; the inlet of the third heat release side is connected to the outlet of the first heat release side, or the inlet of the third heat release side is connected to the outlet of the second hydrogenation furnace.

5. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 4, characterized in that, It also includes an ammonia washing tower, which has a fourth inlet, a fourth outlet, a fifth inlet, and a fifth outlet. The fourth inlet is connected to the outlet on the third exothermic side, the fourth outlet is used to discharge synthesis gas, the fifth inlet is used to connect to a water source, and the fifth outlet is connected to the second inlet.

6. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 5, characterized in that, It also includes a desulfurization and decarbonization device, the inlet of which is connected to the fourth outlet.

7. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 2, characterized in that, It also includes a preliminary purification unit, which comprises an electrostatic precipitator, a low-temperature water washing device, and a compression device. The inlet of the electrostatic precipitator is used to introduce coal pyrolysis gas. The low-temperature water washing device is provided with a sixth inlet, a sixth outlet, a seventh inlet, and a seventh outlet. The sixth inlet is connected to the outlet of the electrostatic precipitator, the seventh inlet is connected to the second outlet, and the seventh outlet is used to discharge liquid. The inlet of the compression device is connected to the sixth outlet, and the outlet of the compression device is connected to the inlet of the first heat absorption side.

8. The system for purifying and converting heat of raw coal gas from coal pyrolysis according to claim 7, characterized in that, It also includes a gas holder, the inlet of which is connected to the outlet of the electrostatic precipitator, and the outlet of which is connected to the sixth inlet of the low-temperature water washing device; And / or, the compression device includes a first compression device, a removal device, and a second compression device, wherein the inlet of the first compression device is the inlet of the compression device, the outlet of the first compression device is connected to the inlet of the removal device, the outlet of the removal device is connected to the inlet of the second compression device, and the outlet of the second compression device is the outlet of the compression device; And / or, it also includes a separator having an eighth inlet, an eighth outlet and a ninth outlet, the eighth inlet being connected to the outlet of the compression device, the eighth outlet being connected to the inlet of the first heat absorption side, and the ninth outlet being connected to the second inlet.

9. A method for coupling the purification and heat conversion of raw coal gas from coal pyrolysis, characterized in that, The purification and conversion of raw coal gas from coal pyrolysis using the system described in any one of claims 1-8 includes the following steps: (1) The raw coal gas from coal pyrolysis is heated after preliminary purification, and then detoxified by a detoxifying adsorbent; after detoxification, it undergoes a hydrogenation deoxygenation reaction to remove oxygen; after hydrogenation deoxygenation, it undergoes an organic chlorine hydrogenation reaction to convert organic chlorine into inorganic chlorine, and then the inorganic chlorine is initially removed by washing, and then humidified by humidifying steam to obtain humidified gas. (2) The humidifying gas is heated and then the inorganic chlorine is further removed by protective adsorption dechlorination through a dechlorination adsorbent; after dechlorination, the first adiabatic transformation reaction is carried out; the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas.

10. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 9, characterized in that, In step (1), the preliminary purification includes: electrostatic precipitator to remove tar and dust from the coal pyrolysis raw coal gas, followed by water washing to further remove tar and dust, and then compression after water washing; And / or, the preliminarily purified raw coal gas is heated to a temperature of 260~280℃; And / or, the preliminarily purified raw coal gas includes at least one of the following: impurities containing lone pairs of electrons, oxygen, organochlorine, organosulfur, and unsaturated hydrocarbons; And / or, in step (1), the detoxification includes removing impurities containing lone pairs of electrons; And / or, the detoxifying adsorbent includes at least one of ZnO, MgO, CaO, CaCO3, Na2CO3 or K2CO3; And / or, the detoxification temperature is 260~280℃; And / or, in step (1), the hydrodeoxygenation reaction is carried out under the catalysis of a first catalyst; the first catalyst includes at least one of a Co-Mo catalyst or an Fe-Mo catalyst; And / or, the initial temperature of the hydrodeoxygenation reaction is 260~280℃, and the outlet temperature is 330~380℃.

11. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 9, characterized in that, In step (1), the organochlorine hydrogenation reaction is carried out under the catalysis of a second catalyst; the second catalyst includes at least one of Pd, Pt, Rh, Ni, Co, Cu or Fe; And / or, the temperature of the organochlorine hydrogenation reaction is not lower than 350°C; And / or, in step (1), the washing includes washing with water; And / or, in step (1), the humidifying steam includes at least one of saturated steam or superheated steam; And / or, the temperature of the humidifying gas is 160~200℃.

12. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 9, characterized in that, In step (2), the temperature of the heated humidifying gas is 220~260℃; And / or, in step (2), the dechlorination adsorbent includes at least one of CaO, MgO, CuO, ZnO, Na2CO3, NaHCO3, Ca(OH)2 or Mg(OH)2; And / or, the temperature for the protective adsorption dechlorination is 220~260℃; And / or, in step (2), the initial activation temperature of the first adiabatic transformation reaction is 220~260℃; And / or, the outlet temperature of the first adiabatic conversion reaction is 350~400℃; And / or, the first adiabatic shift reaction is carried out under the catalysis of a third catalyst, the third catalyst including a Co-Mo based sulfur-resistant shift catalyst.

13. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 9, characterized in that, In step (2), the gas after the first adiabatic transformation undergoes a first hydrogenation reaction to convert organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively. The resulting gas is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas to obtain syngas.

14. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 13, characterized in that, The temperature of the first hydrogenation reaction is 350~380℃; And / or, the first hydrogenation reaction is carried out under the catalysis of a fourth catalyst, the fourth catalyst including a Co-Mo based hydrogenation catalyst; And / or, the resulting gas, after being cooled by the humidifying gas, has a temperature of 270~340℃; And / or, the resulting gas, after being cooled from the pre-purified raw coal gas, has a temperature of 140~220℃; And / or, the resulting gas is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas, and then cooled again.

15. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 9, characterized in that, In step (2), the gas after the first adiabatic transformation is cooled by the humidifying gas and the temperature is 340~360℃; And / or, after the gas undergoing the first adiabatic transformation is cooled by the pre-purified raw coal gas, the temperature is 240~260℃; And / or, the gas after the first adiabatic transformation is cooled sequentially by the humidifying gas and the preliminarily purified raw coal gas, then humidified again by humidifying steam, and then undergoes the second adiabatic transformation reaction; the gas after the second adiabatic transformation undergoes the second hydrogenation reaction, converting organic sulfur and unsaturated hydrocarbons into inorganic sulfur and saturated hydrocarbons, respectively, to obtain syngas.

16. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to claim 15, characterized in that, In step (2), the humidifying steam includes saturated steam; And / or, the temperature of the gas after rehumidification is 220~240℃; And / or, the outlet temperature of the second adiabatic conversion reaction is 270~300℃; And / or, the second adiabatic shift reaction is carried out under the catalysis of a fifth catalyst, which includes a Co-Mo based sulfur-resistant shift catalyst; And / or, the temperature of the second hydrogenation reaction is 270~300℃; And / or, the second hydrogenation reaction is carried out under the catalysis of a sixth catalyst, which includes a Co-Mo based hydrogenation catalyst; And / or, the gas obtained after the second hydrogenation reaction is cooled again.

17. The method for purifying and coupling heat conversion of raw coal gas from coal pyrolysis according to any one of claims 9-16, characterized in that, In step (2), the cooled gas is subjected to ammonia washing to obtain syngas; preferably, the syngas after ammonia washing is subjected to desulfurization and decarbonization. And / or, the syngas is used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

18. A synthesis gas, characterized in that, The syngas is obtained by pyrolysis of raw coal gas using the method described in any one of claims 9-17.

19. An application of the syngas according to claim 18, characterized in that, The syngas is used to prepare methanol, ethanol, ethylene glycol, natural gas, ammonia, or hydrogen.

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