Process system for co-producing solid wax, liquid hydrocarbon and hydrogen through Fischer-Tropsch synthesis of biosynthesis gas

Abstract

The invention relates to the technical field of biosynthesis gas treatment, and particularly discloses a process system for co-producing solid wax, liquid hydrocarbon and hydrogen through Fischer-Tropsch synthesis of biosynthesis gas. Comprising a pre-treatment system, an air blower system, a pre-treatment system, a compression system, a transformation system, a desulfurization system, an MDEA decarburization system, a PSA hydrogen extraction system, a desorbed gas compression system, a fine desulfurization and pressurization system and a Fischer-Tropsch synthesis system which are sequentially connected step by step. According to the process system, the solid wax, the liquid hydrocarbon and the hydrogen are produced in a manner of integrating various technologies such as Fischer-Tropsch synthesis, pressure swing adsorption and the like by utilizing the biosynthesis gas obtained by pyrolysis and gasification of the household garbage. According to the process system, organic matters in the garbage are converted into high-added-value chemicals such as solid wax, liquid hydrocarbon and hydrogen, resource utilization is achieved, and pollution to the environment is reduced. In addition, the process system can adjust the variety and yield of products according to market requirements, and maximization of economic benefits is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of biosyngas processing, and in particular to a process system for co-producing solid wax, liquid hydrocarbons and hydrogen through Fischer-Tropsch synthesis of biosyngas. Background Art

[0002] With the significant increase in public awareness of environmental protection and resource conservation, higher standards for waste treatment technologies have been placed accordingly. Against this backdrop, traditional waste treatment methods—including landfill, composting, and incineration—have gradually exposed their respective shortcomings. First, while landfill is simple and easy to implement, it requires a large amount of land, making it particularly uneconomical in today's increasingly scarce land resources. Second, while composting is a relatively environmentally friendly treatment method, it can only process relatively small amounts of waste and has low efficiency, making it difficult to cope with the growing waste production. Finally, while incineration can effectively reduce waste volume, it is prone to secondary pollution during the treatment process, particularly the emission of highly toxic substances such as dioxins, which pose a significant threat to the environment and hinder industrial application. Therefore, finding more efficient and environmentally friendly waste treatment technologies has become a pressing issue for society.

[0003] To address the challenges of municipal solid waste treatment, domestic researchers are actively exploring the use of fluidized bed pyrolysis and gasification technology to treat organic waste. This process involves cracking organic waste at high temperatures, followed by a condensation step to convert the resulting pyrolysis gases into new gas and solid forms. From a theoretical and practical perspective, this method can effectively reduce the formation of harmful substances such as dioxins. Furthermore, during the pyrolysis and gasification process, most heavy metals dissolve into the ash, significantly reducing emissions of these harmful substances. The resulting mixed gas from treating municipal solid waste in this way is called biosyngas. This gas primarily consists of hydrogen, methane, carbon monoxide, carbon dioxide, and nitrogen, but also contains impurities such as tar, sulfur, chlorine, ammonia, and siloxanes. Currently, the industrial application of biosyngas is still in its infancy, and many countries around the world are actively researching and exploring industrial pathways for converting waste into hydrogen. Despite this, this field is generally still in the research and demonstration stage. Currently, the mainstream treatment method for municipal solid waste is still combustion for power generation or urban heating. While there are some industrial installations in China that produce hydrogen from the pyrolysis of municipal solid waste, their application remains very limited. Given the current situation, a key challenge facing engineers is how to efficiently utilize the biogas produced by the pyrolysis of municipal solid waste and create greater economic value through this process. Summary of the Invention

[0004] The present invention provides a process system for the co-production of solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas. The biosyngas produced by pyrolysis and gasification of domestic waste is sequentially subjected to cascade purification, carbon-hydrogen ratio adjustment, pressure swing adsorption hydrogen extraction and Fischer-Tropsch synthesis processes. By synergistically co-producing high-purity hydrogen, liquid hydrocarbons and solid wax through multiple systems, high-value resource utilization of organic waste and low carbon emissions are achieved.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A process system for the Fischer-Tropsch synthesis of biosyngas to produce solid wax, liquid hydrocarbons and hydrogen, comprising a pretreatment system A, a blower system B, a pretreatment system C, a compression system D, a conversion system E, a desulfurization system F, an MDEA decarbonization system G, a PSA hydrogen extraction system H, a desorption gas compression system I, a fine desulfurization and pressurization system J and a Fischer-Tropsch synthesis system K, which are connected in sequence; wherein the pretreatment system A is used to perform preliminary oil removal treatment on the biosyngas produced by pyrolysis and gasification of domestic waste; the blower system B is used to pressurize the pretreated biosyngas and divert it through a pipeline, with one path supplying fuel gas to the outside and the other path entering the pretreatment system C; the pretreatment system C is used to further remove oil and desulfurize the pressurized biosyngas; the compression system D is used to The purified biosynthesis gas is further pressurized; the conversion system E is used to adjust the molar ratio of hydrogen and carbon monoxide to obtain conversion gas; the desulfurization system F is used to desulfurize the conversion gas; the MDEA decarbonization system G is used to absorb and remove carbon dioxide and separate the by-product carbon dioxide through a pipeline; the PSA hydrogen extraction system H is used to remove hydrogen and adjust the hydrogen production ratio to obtain PSA desorbed gas, and the carbon-rich gas that does not participate in hydrogen extraction is transported to the outlet pipeline of the desorbed gas compression system I through a pipeline; the desorbed gas compression system I is used to pressurize the PSA desorbed gas; the fine desulfurization and pressurization system J is used to further pressurize and finely desulfurize the PSA desorbed gas; the Fischer-Tropsch synthesis system K is used to condense and separate solid wax and liquid hydrocarbons, and at the same time, the obtained purge gas is recycled as fuel gas.

[0007] Furthermore, the pretreatment system A includes a connected electric tar collector and a fiber bed mist collector, the bottom of the electric tar collector is provided with a heating device and the top is provided with a flushing device; the fiber bed mist collector is filled with a loose mesh structure woven with corrosion-resistant and high-temperature resistant fibers.

[0008] Furthermore, the pretreatment system C removes tar from the biosynthesis gas to ≤5 mg / Nm 3 , hydrogen sulfide removal to ≤50mg / Nm 3 The pretreatment system C includes a connected oil removal tower and a desulfurization device. The oil removal tower adopts dry oil removal and is filled with coke, activated carbon and aluminosilicate composite adsorption filler; the desulfurization device adopts dry desulfurization or wet desulfurization.

[0009] Furthermore, the conversion system E uses a wide-temperature sulfur-resistant conversion catalyst, and dynamically controls the molar ratio of hydrogen to carbon monoxide within the range of plus or minus 0.2 of 2 to 1 by adjusting the steam conversion reaction of carbon monoxide and water vapor.

[0010] Furthermore, the desulfurization system F adopts dry desulfurization, and the desulfurization system F adopts a desulfurization tower, and the desulfurization tower is filled with a composite desulfurizer of coke and activated carbon.

[0011] Furthermore, the MDEA decarbonization system G adopts a two-stage absorption process of methyldiethanolamine solution, wherein the lower stage is washed with semi-lean solution and the upper stage is washed with regenerated lean solution.

[0012] Furthermore, the PSA hydrogen extraction system H includes 6 to 12 adsorption towers, and the adsorbent is regenerated by flushing or vacuuming, with the pressure equalization times being 1 to 6 times.

[0013] Furthermore, the fine desulfurization and pressurization system J pressurizes the mixed gas after fine desulfurization to a gauge pressure of 4 to 6 MPa. The operating pressure of the Fischer-Tropsch synthesis system K is consistent with the output pressure of the fine desulfurization and pressurization system J, which is 4 to 6 MPa.

[0014] Furthermore, the fine desulfurization and pressurization system J uses a fine desulfurization tower to remove hydrogen sulfide in the gas to ≤4ppb, and the fine desulfurization tower is filled with a zinc oxide and copper oxide composite fine desulfurizer.

[0015] A method for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosynthesis gas is also provided, comprising the following steps:

[0016] (1) Pretreatment for tar removal: The biosynthesis gas produced by pyrolysis and gasification of domestic waste is introduced into the pretreatment system A, where it is initially degreased by an electric tar collector and a fiber bed mist collector to remove most of the tar.

[0017] (2) Blower pressurization: The pretreated biosyngas is pressurized to a gauge pressure of 20-60 kPa by the blower system B and split into two paths, one for external fuel gas and the other for the pretreatment system C;

[0018] (3) Pretreatment oil removal and desulfurization: The biosynthetic gas entering the pretreatment system C passes through the deoiling tower and desulfurization device in sequence to remove tar to ≤5mg / Nm 3 , hydrogen sulfide removal to ≤50mg / Nm 3 ;

[0019] (4) Compressor pressurization: The purified biosynthetic gas is further pressurized to a gauge pressure of 1.5 to 2.5 MPa by the compression system D;

[0020] (5) Shift reaction: The pressurized gas enters the shift system E. Under the action of a wide-temperature, sulfur-resistant shift catalyst, the steam shift reaction of carbon monoxide and water vapor is regulated to control the molar ratio of hydrogen to carbon monoxide at 2:1±0.2 to obtain shift gas.

[0021] (6) Desulfurization treatment: The conversion gas is passed into the dry desulfurization tower of the desulfurization system F, and a composite desulfurizer of coke and activated carbon is used to remove hydrogen sulfide to ≤1mg / Nm 3 ;

[0022] (7) MDEA decarbonization: The desulfurized gas enters the MDEA decarbonization system G, where carbon dioxide is removed to ≤50ppm and the by-product carbon dioxide is separated;

[0023] (8) PSA hydrogen extraction: The decarbonized gas enters the PSA hydrogen extraction system H, and is separated into product hydrogen through a pressure swing adsorption process in 6 to 12 adsorption towers; the carbon-rich gas in the decarbonized gas that does not participate in hydrogen extraction is directly transported to the outlet pipeline of the desorption gas compression system I through a pipeline, and is combined with the PSA desorption gas remaining after hydrogen extraction and then enters the desorption gas compression system I;

[0024] (9) Desorbed gas compression: PSA desorbed gas is pressurized to a gauge pressure of 1.5-2.5 MPa via desorbed gas compression system I;

[0025] (10) Fine desulfurization and pressurization: The pressurized desorbed gas enters the fine desulfurization and pressurization system J, passes through the fine desulfurization tower filled with zinc oxide and copper oxide composite desulfurizer, removes hydrogen sulfide to ≤4ppb, and further pressurizes to 4-6 MPa gauge pressure;

[0026] (11) Fischer-Tropsch synthesis: The gas after fine desulfurization and pressurization is introduced into the Fischer-Tropsch synthesis system K. Under the conditions of 4-6 MPa gauge pressure and 160-200°C, hydrocarbon products are synthesized by catalysis. Solid wax and liquid hydrocarbons are separated by condensation, and the purge gas is recycled as fuel gas.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The process system of the present invention for producing solid wax, liquid hydrocarbons and co-produced hydrogen by Fischer-Tropsch synthesis of biosyngas mainly consists of a pretreatment system, a blower system, a pretreatment system, a compression system, a conversion system, a desulfurization system, an MDEA decarbonization system, a PSA hydrogen extraction system, a desorption gas compression system, a fine desulfurization and pressurization system and a Fischer-Tropsch synthesis system. Among them, the pretreatment system effectively removes impurities in the biosyngas through equipment such as electrostatic precipitators and fiber bed mist collectors, ensuring the high efficiency of subsequent treatment; the pretreatment system further performs deep oil removal and desulfurization to ensure that components such as hydrogen sulfide in the biosyngas meet the process requirements; the compression system and conversion system increase the concentration of hydrogen and CO in the biosyngas through compression and conversion reactions, providing high-quality raw materials for the subsequent PSA hydrogen extraction system; the desulfurization system and MDEA decarbonization system respectively deeply remove sulfides and carbon dioxide from the biosyngas to ensure gas purity; the PSA hydrogen extraction system can produce high-purity hydrogen according to the needs of downstream hydrogen users, and at the same time send the hydrogen-extracted gas to the desorption gas compression system; the fine desulfurization and pressurization system further removes trace sulfides in the gas, improving the gas purity; the Fischer-Tropsch synthesis system uses carbon monoxide and hydrogen to synthesize liquid hydrocarbons and solid wax under specific temperature and pressure conditions, realizing the full conversion of waste resources and the production of high-value-added chemicals. The working principle of the entire system is to utilize the biosynthetic gas produced by the pyrolysis and gasification of domestic waste, and through pretreatment, compression, transformation, desulfurization, hydrogen extraction, fine desulfurization, pressurization and other steps, finally obtain solid wax, liquid hydrocarbons and hydrogen through Fischer-Tropsch synthesis, greatly improving the economic and environmental benefits of waste treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a process system for the co-production of solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the embodiments described are only some of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] Example

[0032] like Figure 1As shown, the present invention provides a process system for producing high-purity hydrogen from bio-crude synthesis gas and co-producing bio-natural gas, comprising a purification unit 1, a carbon-hydrogen adjustment unit 2, an acid removal unit 3, a methane upgrading unit 4, a recycling and purification unit for hydrogen 5, and a recycling and purification unit for methane 6, which are connected in sequence; specifically, the bio-synthesis gas is connected to the pretreatment system A through a pipeline 1; the pretreatment system A is connected to the blower system B through a pipeline; the blower system B is connected to the pretreatment system C through a pipeline; the pressurized bio-synthesis gas at the outlet of the blower system B is sent out through a pipeline 2 as an external fuel gas; the pretreatment system C is connected to the compression system D through a pipeline; the compression system D is connected to the conversion system E through a pipeline; the conversion system E is connected to the desulfurization system F through a pipeline; the desulfurization system F is connected to the MD through a pipeline. EA decarbonization system G is connected; the CO2 absorbed by the MDEA decarbonization system G is discharged at a high point on site through pipeline 3; the MDEA decarbonization system G is connected to the PSA hydrogenation system H through a pipeline; the MDEA decarbonization system G is connected to the outlet pipeline of the desorption gas compression system I through pipeline 5; the product hydrogen produced by the PSA hydrogenation system H is transported through pipeline 4; the PSA hydrogenation system H is connected to the desorption gas compression system I through a pipeline; the desorption gas compression system I is connected to the fine desulfurization and pressurization system J through a pipeline; the fine desulfurization and pressurization system J is connected to the Fischer-Tropsch synthesis system K through a pipeline; the liquid hydrocarbons produced by the Fischer-Tropsch synthesis system K are transported through pipeline 6; the solid wax produced by the Fischer-Tropsch synthesis system K is transported through pipeline 7; the purge gas of the Fischer-Tropsch synthesis system K is transported as fuel gas through pipeline 8.

[0033] The pretreatment system A is used to perform preliminary oil removal on the 2-4 kPa (G) and 40°C biosyngas generated by the pyrolysis and gasification of municipal solid waste. It comprises a connected electrostatic precipitator (ETC) and a fiber bed mist collector. The ETC, the fiber bed mist collector, and other devices remove the majority of the tar from the biosyngas. The ETC utilizes a honeycomb structure, which effectively improves the device's collection efficiency. A steam heater is installed at its base, which not only helps maintain the device's normal operating temperature but also prevents tar accumulation within the device. A dedicated flushing device is installed at the top of the ETC for regular cleaning of the device's surface to maintain optimal operating conditions. The fiber bed mist collector utilizes a core-type loose fiber bed, secured to the device by a tube sheet, ensuring stability and durability. The fiber bed is a loose mesh structure woven from extremely fine fibers. Its large surface area significantly agglomerates fine dust droplets, resulting in extremely high separation efficiency. Additionally, this fiber bed mist eliminator offers advantages such as easy cleaning, corrosion-resistant materials, and the ability to withstand high temperatures, making it an excellent performer in a variety of industrial applications.

[0034] The blower system B is used to pressurize the pre-treated biosyngas to 20-60 kPa (G). The blower system B uses a blower to separate the pressurized biosyngas into two paths: one path is supplied to the outside through pipeline 2 as fuel gas, and the other path enters the pre-treatment system C.

[0035] The pretreatment system C performs deep deoiling and desulfurization on the pressurized biosynthesis gas. The pretreatment system C includes a connected deoiling tower and a desulfurization device, specifically, two connected dry deoiling towers and one dry desulfurization tower. The pressurized biosynthesis gas is passed through the dry deoiling tower to remove tar to ≤5mg / Nm 3 The de-oiling tower is filled with tar adsorption fillers such as coke, activated carbon, and aluminosilicate. The pressurized biosynthesis gas is passed through the desulfurization device to remove hydrogen sulfide in the biosynthesis gas to ≤50mg / Nm 3 The desulfurization device adopts dry desulfurization or wet desulfurization method according to the hydrogen sulfide content of the biosynthesis gas.

[0036] Compression system D is used to further pressurize the purified biosyngas to 1.5-2.5 MPa. The compressors used in compression system D are either reciprocating or centrifugal. Specifically, two connected centrifugal compressors are used. The core objective of this step is to increase the operating pressure of the purified biosyngas. When selecting the pressure, key considerations include the user's specific hydrogen pressure requirements, as well as a comprehensive assessment of the investment costs, energy consumption, and process removal efficiency of each unit.

[0037] The shift system E is used to adjust the molar ratio of hydrogen and carbon monoxide to produce the desired shifted gas. The shift system E includes a feed preheater, a detoxification furnace, a humidifier, a primary shift furnace, a waste heat boiler, a secondary shift furnace, a heat exchanger group, and a cooling unit. Among them, the feed preheater receives the biosynthesis gas (pressure 1.5-2.5MPa (G), temperature about 130°C) output by the compression system D, and heats the gas to 180-230°C through heat exchange; the outlet of the feed preheater is connected to the inlet of the detoxification furnace, and the gas is detoxified by oxygen (O2 <1ppm), arsenic, chlorine and other poisons in the detoxification furnace, and the temperature rises to about 300°C (the temperature rise is determined by the content of impurities); the gas at the outlet of the detoxification furnace enters the humidifier, and the temperature is reduced to about 220°C by spraying water / steam; the outlet of the humidifier is connected to the inlet of the first-stage conversion furnace, and the gas undergoes the main conversion reaction under isothermal conditions (it can also be designed as adiabatic conditions according to the conditions of the raw gas), and the outlet temperature of the conversion furnace is about 250°C; the heat generated by the conversion reaction in the first-stage conversion furnace is buried in the catalyst bed The water heat transfer tube bundle produces 1.0~2.5MPa(G) saturated steam as a by-product. The water heat transfer tube bundle in the first-stage converter is connected to the waste heat boiler; the outlet of the first-stage converter is connected to the inlet of the second-stage converter to complete the deep conversion (the CO concentration is determined by the hydrogen content, and the purpose is to adjust the molar ratio of CO and H2). The outlet temperature is controlled at around 220℃; the heat exchanger group includes a deoxygenated water preheater and a desalted water preheater. The gas at the outlet of the second-stage converter of the deoxygenated water preheater is cooled to about 180℃ by the deoxygenated water preheater; the desalted water preheater further cools it to 120℃; the cooling unit includes an air cooler and a water cooler. The outlet of the deoxygenated water preheater is connected to the air cooler, and the gas temperature is reduced to 60℃; the outlet of the air cooler is connected to the water cooler, and the converted gas is finally cooled to below 40℃ and transported to the desulfurization system F.

[0038] The feed preheater is used to heat the compressed biosynthesis gas (about 130°C) to the catalytic reaction temperature (such as 180°C); the detoxification furnace is equipped with a deoxidizer and adsorbent to remove residual O2 (O2 < 1ppm) and poisons such as arsenic and chlorine in the gas, and the outlet temperature is raised to about 300°C; the humidifier adjusts the temperature of the high-temperature gas by spraying water / steam (such as down to 220°C) and replenishes water vapor; the first-stage conversion furnace is loaded with a wide-temperature sulfur-resistant catalyst (such as Co-Mo system) and performs the main conversion reaction under isothermal conditions (CO conversion rate 60% to 80%), and the outlet temperature is raised to about 250°C; the waste gas is heated to 100°C and the waste gas is heated to 200°C. The heat boiler recovers the reaction heat and by-product steam (pressure 1.0-2.5 MPa) while simultaneously cooling the gas to below 200°C. The second-stage shift converter further achieves deep shift conversion (CO concentration ≤ 15%), employing an isothermal reactor or interstage cooling design, with the outlet temperature controlled at 220°C ± 10°C. The heat exchanger, consisting of a deoxygenated water preheater and a desalted water preheater, recovers waste heat in stages (reducing the gas temperature from 220°C to 80°C). The cooling unit, consisting of an air cooler (air cooling) and a water cooler (circulating water cooling), ultimately reduces the shift gas temperature to below 40°C, meeting the inlet requirements of the desulfurization system. This shift system (E) processes the high-pressure purified biogas over a gas-solid catalyst, converting the CO and water vapor contained therein into H2 and CO2. This process aims to produce more hydrogen and adjust the hydrogen-to-carbon ratio of the shifted biogas to meet Fischer-Tropsch synthesis requirements. The basic chemical reaction equation can be expressed as: CO + H2O = CO2 + H2. Shift System E flexibly adjusts the unit's primary product based on market fluctuations, primarily adjusting the ratio of H₂ to CO in the converted biosyngas. Without hydrogen production, Shift System E ensures a roughly 2:1 H₂ to CO ratio in the converted biosyngas, suitable for the Fischer-Tropsch synthesis unit.

[0039] The desulfurization system F is used to deeply remove H2S from the converted biosynthesis gas. The desulfurization system F adopts dry desulfurization, and the desulfurization system F adopts a dry desulfurization tower, which is filled with desulfurization adsorbents such as coke and activated carbon. The converted biosynthesis gas passes through the desulfurization tower to remove H2S to ≤1mg / Nm 3 .

[0040] The MDEA decarbonization system G is used to absorb and remove carbon dioxide and separate the byproduct carbon dioxide through a pipeline. It uses a methyldiethanolamine solution (MDEA solution) in a two-stage absorption process, with the lower stage being scrubbed with semi-lean liquid and the upper stage being scrubbed with regenerated lean liquid. The MDEA decarbonization system G removes CO2 from the degassing gas to below 50 ppm. Specifically, the MDEA decarbonization system G includes a feed gas-liquid separator, a two-stage absorption tower, a rich liquid flash tank, a lean-rich liquid heat exchanger, a regeneration tower, a lean liquid circulation pump, and a semi-lean liquid circulation pump. The gas-liquid separator of the raw gas is used to separate the condensed water entrained in the conversion gas; the two-stage absorption tower includes a lower absorption zone and an upper absorption zone. The lower absorption zone is filled with structured packing, and the inlet is connected to a semi-lean liquid circulation pump, and a semi-lean MDEA solution (a mixture of lean liquid and rich liquid) is used to initially absorb CO2; the upper absorption zone is filled with random packing, and the inlet is connected to a lean liquid cooler, and the regenerated lean liquid is used to deeply remove CO2 to ≤50ppm; the rich liquid flash tank is used to receive the rich liquid (MDEA solution rich in CO2) at the bottom of the absorption tower and release the dissolved gas by reducing the pressure; the lean and rich liquid heat exchanger uses the high temperature at the bottom of the regeneration tower to regenerate the CO2. The rich liquid after the lean liquid is heated and flashed is heated to increase the temperature of the rich liquid to 100-110°C; the regeneration tower includes a reboiler and a tower top condenser, and the reboiler is heated by steam (0.3-0.5Mpa(G)) to make the rich liquid desorb CO2 at 120-130°C; the tower top condenser condenses and dehydrates the desorbed CO2 gas to obtain high-purity CO2 (≥99.5%) and discharges it through pipeline 3; the lean liquid circulation pump cools the lean liquid at the bottom of the regeneration tower to 40-50°C through the cooler and then pumps it to the upper section of the absorption tower; the semi-lean liquid circulation pump extracts semi-lean liquid from the middle of the regeneration tower and directly transports it to the lower section of the absorption tower.

[0041] The MDEA decarbonization system G absorbs and removes carbon dioxide, and separates the byproduct carbon dioxide through a pipeline as follows: The degassing process first enters the feed gas gas-liquid separator for gas-liquid separation. The separated gas enters the lower inlet of the absorber tower, is scrubbed with semi-lean liquid in the lower absorption zone, and then enters the upper absorption zone. After further scrubbing with lean liquid, purified gas is discharged from the top of the absorber tower and transported to the PSA hydrogen extraction system H. The carbon dioxide gas desorbed at the top of the regeneration tower is dehydrated in the overhead condenser and vented through the high point of pipeline 3. The rich liquid output from the bottom of the absorber tower is depressurized and flash-evaporated in a rich liquid flash tank. It then heats up with the high-temperature lean liquid through a lean-rich liquid heat exchanger before entering the middle of the regeneration tower. The high-temperature lean liquid at the bottom of the regeneration tower is pressurized by a lean liquid circulation pump, first cooled by heat exchange with the rich liquid through a lean-rich liquid heat exchanger, and then cooled to 40-50°C in a lean liquid cooler before being transported to the upper inlet of the absorber tower. The semi-lean liquid in the middle of the regeneration tower is directly transported to the lower inlet of the absorber tower via a semi-lean liquid circulation pump. The high-temperature lean liquid at the bottom of the regeneration tower completes heat exchange with the rich liquid in the lean-rich liquid heat exchanger, and then enters the lean liquid cooler for further cooling; the steam condensate from the reboiler is returned to the boiler through a pipeline for recycling.

[0042] The PSA hydrogen extraction system H is used to remove hydrogen and adjust the hydrogen production ratio to produce PSA desorbed gas. The carbon-rich gas that does not participate in hydrogen extraction is piped to the outlet of the desorbed gas compression system I. The process flow of the PSA hydrogen extraction system H utilizes 6 to 12 adsorption towers, with 1 to 6 pressure equalization cycles. Adsorbent regeneration is performed by flushing or vacuuming. The PSA hydrogen extraction system H is designed to flexibly adjust its production load based on the company's internal hydrogen demand. This adjustment ensures that the system can efficiently meet the specific needs of downstream hydrogen users. The demand for hydrogen primarily comes from these users, who have clear requirements for hydrogen usage and quality standards. After the PSA hydrogen extraction system H completes the hydrogen production process, some raw material purified biosynthesis gas will remain. This excess gas is channeled through pipeline 5 to the outlet of the desorbed gas compression system I. This design not only optimizes gas utilization efficiency but also reduces resource waste. Furthermore, the PSA Hydrogen Generation System H is capable of adjusting hydrogen purity based on the needs of downstream hydrogen users, producing hydrogen with purities ranging from 99% to 99.999%. This high-purity hydrogen is not only suitable for general industrial applications but also meets the stringent standards for hydrogen used in hydrogen fuel cells, thus enabling the widespread application of hydrogen energy.

[0043] The desorbed gas compression system I is used to pressurize the PSA desorbed gas; specifically, the desorbed gas compression system I pressurizes the PSA desorbed gas of the PSA hydrogen extraction system H to 1.5-2.5 MPa (G).

[0044] The fine desulfurization and pressurization system J is used to further pressurize and finely desulfurize the PSA desorbed gas. It removes H2S from the purified and hydrogen-extracted PSA desorbed gas to ≤4 ppb, and then pressurizes the desulfurized PSA desorbed gas to 4-6 MPa(G). Specifically, the purified and hydrogen-extracted PSA desorbed gas passes through a fine desulfurization tower to remove H2S from the gas to ≤4 ppb. Fine desulfurization utilizes dry desulfurization, and the tower is loaded with fine desulfurizers such as zinc oxide and copper oxide.

[0045] The Fischer-Tropsch synthesis system K is used to condense and separate solid wax and liquid hydrocarbons, and at the same time, recycle the obtained purge gas as fuel gas. The Fischer-Tropsch synthesis system K is a process in which carbon monoxide and hydrogen are synthesized into hydrocarbon products by a Co catalyst at 160-200°C and a pressure of ~4.0MPa. The main products are divided into liquid products (gasoline and diesel components) and solid products (high-end synthetic wax). The purge gas generated by the Fischer-Tropsch synthesis system K is transported as fuel gas through pipeline 8. Specifically, the Fischer-Tropsch synthesis system K includes a shell-and-tube coupled heat exchanger, a Fischer-Tropsch synthesis reactor, a multi-stage condenser, a gas-liquid-solid three-phase separator, a purge gas circulation compressor and a product collection tank.

[0046] Among them, the synthesis gas from the fine desulfurization and pressurization system J is mixed with the circulating process gas from the outlet of the multi-stage condenser, and then enters the shell-and-tube coupled heat exchanger for preheating to a temperature close to the reaction temperature (160-200°C); the preheated mixed gas is transported to the Fischer-Tropsch synthesis reactor, and a hydrocarbon synthesis reaction is carried out under the conditions of Co-based catalyst and ~4.0Mpa(G); the products at the outlet of the reactor enter the multi-stage condenser in turn for step-by-step cooling (temperature gradient controlled at 200°C→120°C→40°C), and liquid hydrocarbons and solid wax are separated; the condensed gas-liquid-solid mixture enters the gas-liquid-solid three-phase separator, and the liquid hydrocarbons are sent to the storage tank through pipeline 6, and the solid wax is sent to the outside for packaging through pipeline 7. The uncondensed gas is divided into two paths: one path is used as purge gas to supply fuel gas through pipeline 8; the other path is pressurized by the purge gas circulation compressor and then returns to the inlet of the shell-and-tube coupled heat exchanger for circulation reaction.

[0047] The gasification raw gas conditions of the biosyngas comprehensive utilization device in a certain city's domestic waste harmless treatment project are as follows:

[0048] Components <![CDATA[H2]]> CO <![CDATA[CO2]]> <![CDATA[CH4]]> <![CDATA[O2]]> <![CDATA[N2]]> total Vol,% 32.5 39.7 6.4 19 0.4 2 100

[0049] 1. Biosynthesis gas is saturated with water.

[0050] 2. The tar content of biosynthesis gas is 300mg / Nm 3 .

[0051] 3. Total sulfur content of biosynthesis gas: 300mg / Nm 3 .

[0052] 4. Biosynthetic gas contains impurities such as siloxane, ammonia, dioxin, chlorine, arsenic, and Ar.

[0053] The process system according to the embodiment of the present invention is used to process the biosyngas, including the following steps:

[0054] (1) Pretreatment for tar removal: The biosynthetic gas at 2-3 kPa (G) and 40°C from the off-site gas tank enters the pretreatment system A, where most of the tar in the biosynthetic gas is removed through the electric tar collector, fiber bed mist collector and other equipment.

[0055] (2) Blower pressurization: The pretreated biosyngas is pressurized to 40 kPa (G) by the blower in the blower system B. After pressurization, the biosyngas is divided into two paths, one for external fuel gas and the other for the pretreatment system C.

[0056] (3) Pretreatment oil removal and desulfurization: The biosynthetic gas from the blower enters the two dry deoiling towers in the pretreatment system C, which removes the tar in the biosynthetic gas to 1 mg / Nm 3 The gas then enters the dry desulfurization tower to remove H2S from the biosynthesis gas to 30-50 mg / Nm3 .

[0057] (4) Compressor pressurization: The biosynthetic gas at 30 kPa (G) and 40°C enters the two centrifugal compressors in the compression system D and is pressurized to 2.0 MPa (G).

[0058] (5) Conversion: The conversion system E converts CO and steam in the biosyngas into H2 and CO2 under the action of gas-solid phase catalysts in order to obtain more hydrogen. The reaction equation is as follows:

[0059] CO+H2O=CO2+H2△Ho298=-41.4KJ / mol

[0060] Specifically, the biosyngas, after being pressurized by the centrifugal compressor in step 4, does not require cooling through a cooler, maintaining a temperature of approximately 130°C and a pressure of 2.0 MPa(G). This gas is first heated in a feed preheater to approximately 180°C. After heating, it is introduced into a detoxification furnace for detoxification and deoxygenation, during which the gas outlet temperature rises to approximately 300°C. Next, the gas is sprayed with water through a humidifier to cool it, and an appropriate amount of steam is added to prepare it for entry into the first stage of the shift converter for the shift reaction. After the first stage of the shift reaction, the gas enters a waste heat boiler to recover its heat as byproduct steam. The gas then passes through a feed preheater again to approximately 200°C before entering the second stage of the shift converter to complete the remaining shift reaction. After the second stage of the reaction, the gas outlet temperature is approximately 220°C, and the carbon monoxide content is reduced to below 15%. Finally, the converted gas will pass through a deoxygenated water preheater and a desalted water preheater to recover the remaining heat, and then pass through an air cooler and a water cooler for cooling, with the final temperature dropping to approximately 40°C.

[0061] (6) Shift desulfurization: The shifted gas enters the dry desulfurization tower in the desulfurization system F to remove hydrogen sulfide to 5 mg / Nm 3 the following.

[0062] (7) MDEA decarbonization: The degassing passes through the raw gas gas-liquid separator in the MDEA decarbonization system G, separates the condensed water and enters the lower part of the absorption tower. The gas is first washed with semi-lean liquid in the lower part of the absorption tower, and part of the CO2 and H2S are absorbed. Then, the gas is washed with regenerated lean liquid in the upper part of the absorption tower to remove the CO2 in the purified gas to below 50ppm.

[0063] (8) PSA hydrogen extraction: The decarbonized gas enters the adsorption tower in the PSA hydrogen extraction system H, which is in an adsorption state, from the bottom of the tower. In the continuous selective adsorption process of multiple adsorbents, various impurities are effectively adsorbed and removed. In this process, the hydrogen that is not captured by the adsorbent will flow out from the top of the adsorption tower. Subsequently, the hydrogen will be stabilized by a pressure regulating system to ensure its pressure is stable, and then sent to the subsequent process section. After the above treatment, high-purity hydrogen with a purity of more than 99.999% can be obtained. This high-purity hydrogen has extremely high value in many industrial applications.

[0064] (9) Desorbed gas compression: The desorbed gas pressure after hydrogen extraction from PSA is only ~0.03MPa(G). After being pressurized to 1.6MPa by a centrifugal or reciprocating compressor, it enters the fine desulfurization and pressurization unit to deeply remove sulfur from the desorbed gas.

[0065] (10) Fine desulfurization and pressurization: There is a trace amount of organic sulfur in the pressurized desorbed gas, and the conversion unit cannot convert all of the organic sulfur into H2S. After the conversion, the gas is relatively clean and the organic sulfur content is low, so only one stage of hydrogenation is required. The pressurized desorbed gas is heated to about 220-250℃ through a gas-to-gas heat exchanger and a steam heater, and then enters the hydrogenation reactor. Here, the organic sulfur in the desorbed gas reacts with hydrogen to convert the organic sulfur into inorganic sulfur.

[0066] The reaction equation is as follows:

[0067] Olefin saturation C2H4+H2→C2H6

[0068] Mercaptan: RSH+H2→RH+H2S

[0069] Sulfide: R1SR2+2H2→R1H+R2H+H2S

[0070] Disulfide: R1SSR2+3H2→R1H+R2H+2H2S

[0071] Thiophene: C4H4S+4H2→C4H 10 +H2S

[0072] Carbon oxysulfide: COS+H2→CO+H2S

[0073] Carbon disulfide: CS2+4H2→CH4+2H2S

[0074] The pressurized desorbed gas undergoes a primary hydrogenation reaction, using a cobalt-molybdenum hydrogenation catalyst, to convert organic sulfur into hydrogen sulfide. Following hydrogenation, zinc oxide desulfurization is used to remove the total sulfur content in the purified gas to less than 4 ppb, meeting the sulfur requirements of the Fischer-Tropsch synthesis catalyst.

[0075] The desorbed gas after fine desulfurization is pressurized to about 4.0 MPa (G) through a centrifugal or reciprocating compressor and enters the Fischer-Tropsch synthesis unit.

[0076] (11) Fischer-Tropsch Synthesis: Fischer-Tropsch Synthesis (FTS) is a chemical process that involves converting carbon monoxide and hydrogen into hydrocarbon products under specific temperature and pressure conditions using an appropriate catalyst. The basic chemical reaction of this process can be expressed as:

[0077] nCO+(2n+1)H2→CnH 2n+2 +nH2O

[0078] The raw synthesis gas obtained after being processed by the gas treatment unit will be combined with the process gas after multi-stage condensation treatment. Subsequently, these gas mixtures will enter the shell and tube coupled heat exchanger, where they are preheated to a temperature close to that required for the reaction. After preheating, the mixed gas enters the Fischer-Tropsch synthesis reactor, where a chemical reaction occurs, ultimately generating Fischer-Tropsch synthesis products, including solid wax and light hydrocarbons. Depending on the regional characteristics of the enterprise and changes in the market environment, these products can be combined and adjusted within a certain range to better meet market demand. In addition, Fischer-Tropsch products can be further processed according to the specific circumstances of the market segment, such as extracting elemental straight-chain alkanes. Synthetic wax can also be deeply processed to produce various special waxes, thereby increasing the value of the product by more than 30%.

[0079] After the biosynthesis gas is processed through the above steps, the final material balance is shown in Table 1:

[0080] Table 1 Material balance

[0081]

[0082] The Fischer-Tropsch synthesis product data sheet records in detail the specific information of various products produced in the Fischer-Tropsch synthesis process, as shown in Table 2:

[0083] Table 2 Fischer-Tropsch synthesis product data sheet

[0084]

[0085]

[0086] In summary, in the process system of the present invention, the pretreatment system A effectively removes tar and most of the fine droplets in the biosynthesis gas through the electric tar collector and the fiber bed mist collector, thereby improving the efficiency of the subsequent treatment steps and the utilization rate of the catalyst; the blower system B pressurizes the purified biosynthesis gas to the specified pressure, ensuring the reaction conditions of the conversion system; the deoiling tower and desulfurization tower in the pretreatment system C further purify the biosynthesis gas to meet the requirements of the subsequent Cost-Tropsch synthesis; the compression system D improves the thermal efficiency of the gas and reduces energy consumption through pressurization treatment with a centrifugal compressor; the conversion system E performs adiabatic or isothermal reaction through a wide-temperature sulfur-resistant conversion catalyst, greatly improving the hydrogen yield and adapting to market demand; The sulfur system F uses dry desulfurization to effectively reduce the negative impact of sulfides on the catalyst; the MDEA decarbonization system G uses MDEA solution to remove carbon dioxide from the biosynthesis gas, further purifying the gas; the PSA hydrogen extraction system H uses multiple adsorption towers and equalization technology to improve the purity and output of hydrogen to meet the requirements of different applications; the desorbed gas compression system I pressurizes the desorbed gas from the PSA hydrogen extraction system to ensure the continuity of the gas line; the fine desulfurization and pressurization system J further removes sulfides and pressurizes to ensure the operating conditions of the Fischer-Tropsch synthesis system; the Fischer-Tropsch synthesis system K catalytically synthesizes hydrocarbon products under certain temperature and pressure conditions, producing a variety of products such as solid wax, liquid hydrocarbons and hydrogen, achieving efficient utilization of resources. Its working principle is as follows: the biosynthetic gas produced by the pyrolysis and gasification of domestic waste undergoes multiple steps such as pretreatment, pressurization, and purification, and then enters the conversion system to generate hydrogen. The hydrogen is purified and distributed through the PSA hydrogen extraction system, and the remaining gas continues to undergo Fischer-Tropsch synthesis to generate solid wax and liquid hydrocarbons. The entire process system works in coordination to achieve efficient and comprehensive utilization of biosynthetic gas, reduce environmental pollution, and improve economic benefits.

[0087] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any technician familiar with the present profession can make slight changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process system for the co-production of solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas, characterized in that: It includes a pretreatment system A, a blower system B, a pretreatment system C, a compression system D, a conversion system E, a desulfurization system F, an MDEA decarbonization system G, a PSA hydrogenation system H, a desorbed gas compression system I, a fine desulfurization and pressurization system J, and a Fischer-Tropsch synthesis system K, which are connected in sequence. Among them, the pretreatment system A is used to perform preliminary oil removal treatment on the biosynthetic gas produced by pyrolysis and gasification of domestic waste; the blower system B is used to pressurize the pretreated biosynthetic gas and divert it through pipelines, one path is supplied to the outside for fuel gas, and the other path enters the pretreatment system C; the pretreatment system C is used to further remove oil and desulfurize the pressurized biosynthetic gas; the compression system D is used to further pressurize the purified biosynthetic gas; the conversion system E is used to adjust the molar ratio of hydrogen and carbon monoxide to obtain conversion gas; the desulfurization system F is used to desulfurize the conversion gas Treatment; the MDEA decarbonization system G is used to absorb and remove carbon dioxide and separate the by-product carbon dioxide through a pipeline; the PSA hydrogen extraction system H is used to remove hydrogen and adjust the hydrogen production ratio to obtain PSA desorbed gas, and the carbon-rich gas that does not participate in hydrogen extraction is transported to the outlet pipeline of the desorbed gas compression system I through a pipeline; the desorbed gas compression system I is used to pressurize the PSA desorbed gas; the fine desulfurization and pressurization system J is used to further pressurize and finely desulfurize the PSA desorbed gas; the Fischer-Tropsch synthesis system K is used to condense and separate solid wax and liquid hydrocarbons, and at the same time, the obtained purge gas is recycled as fuel gas.

2. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The pretreatment system A includes a connected electric tar collector and a fiber bed mist collector. The bottom of the electric tar collector is provided with a heating device and the top is provided with a flushing device; the fiber bed mist collector is filled with a loose mesh structure woven with corrosion-resistant and high-temperature resistant fibers.

3. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The pretreatment system C removes tar from the biosynthesis gas to ≤5 mg / Nm 3 , hydrogen sulfide is removed to ≤ 50mg / Nm 3 The pretreatment system C includes a connected oil removal tower and a desulfurization device. The oil removal tower adopts dry oil removal and is filled with coke, activated carbon and aluminosilicate composite adsorption filler; the desulfurization device adopts dry desulfurization or wet desulfurization.

4. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The conversion system E uses a wide-temperature sulfur-resistant conversion catalyst and dynamically controls the molar ratio of hydrogen to carbon monoxide within a range of plus or minus 0.2 of 2 to 1 by regulating the steam conversion reaction of carbon monoxide and water vapor.

5. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The desulfurization system F adopts dry desulfurization. The desulfurization system F adopts a desulfurization tower, and the desulfurization tower is filled with a composite desulfurizer of coke and activated carbon.

6. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The MDEA decarbonization system G adopts a two-stage absorption process of methyldiethanolamine solution, wherein the lower stage is washed with semi-lean solution and the upper stage is washed with regenerated lean solution.

7. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The PSA hydrogen extraction system H includes 6 to 12 adsorption towers. The adsorbent is regenerated by flushing or vacuuming, and the pressure equalization times are 1 to 6 times.

8. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 1, characterized in that: The fine desulfurization and pressurization system J pressurizes the mixed gas after fine desulfurization to a gauge pressure of 4 to 6 MPa. The operating pressure of the Fischer-Tropsch synthesis system K is consistent with the output pressure of the fine desulfurization and pressurization system J, which is 4 to 6 MPa.

9. The process system for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas according to claim 8, characterized in that: The fine desulfurization and pressurization system J uses a fine desulfurization tower to remove hydrogen sulfide in the gas to ≤4ppb, and the fine desulfurization tower is filled with a composite fine desulfurizer of zinc oxide and copper oxide.

10. A method for co-producing solid wax, liquid hydrocarbons and hydrogen by Fischer-Tropsch synthesis of biosyngas, characterized in that: The following steps are involved: (1) Pretreatment for tar removal: The biosynthesis gas produced by pyrolysis and gasification of domestic waste is introduced into the pretreatment system A, where it is initially degreased by an electric tar collector and a fiber bed mist collector to remove most of the tar. (2) Blower pressurization: The pretreated biosyngas is pressurized to a gauge pressure of 20-60 kPa by the blower system B and split into two paths, one for external fuel gas and the other for the pretreatment system C; (3) Pretreatment oil removal and desulfurization: The biosynthetic gas entering the pretreatment system C passes through the deoiling tower and desulfurization device in sequence to remove tar to ≤5mg / Nm 3 , hydrogen sulfide removal to ≤50mg / Nm 3 ; (4) Compressor pressurization: The purified biosynthetic gas is further pressurized to a gauge pressure of 1.5 to 2.5 MPa by the compression system D; (5) Shift reaction: The pressurized gas enters the shift system E. Under the action of a wide-temperature, sulfur-resistant shift catalyst, the steam shift reaction of carbon monoxide and water vapor is regulated to control the molar ratio of hydrogen to carbon monoxide at 2:1±0.2 to obtain shift gas. (6) Desulfurization treatment: The conversion gas is passed into the dry desulfurization tower of the desulfurization system F, and a composite desulfurizer of coke and activated carbon is used to remove hydrogen sulfide to ≤1mg / Nm 3 ; (7) MDEA decarbonization: The desulfurized gas enters the MDEA decarbonization system G, where carbon dioxide is removed to ≤50ppm and the by-product carbon dioxide is separated; (8) PSA hydrogen extraction: The decarbonized gas enters the PSA hydrogen extraction system H, and is separated into product hydrogen through a pressure swing adsorption process in 6 to 12 adsorption towers; the carbon-rich gas in the decarbonized gas that does not participate in hydrogen extraction is directly transported to the outlet pipeline of the desorption gas compression system I through a pipeline, and is combined with the PSA desorption gas remaining after hydrogen extraction and then enters the desorption gas compression system I; (9) Desorbed gas compression: PSA desorbed gas is pressurized to a gauge pressure of 1.5-2.5 MPa via desorbed gas compression system I; (10) Fine desulfurization and pressurization: The pressurized desorbed gas enters the fine desulfurization and pressurization system J, passes through the fine desulfurization tower filled with zinc oxide and copper oxide composite desulfurizer, removes hydrogen sulfide to ≤4ppb, and further pressurizes to 4-6 MPa gauge pressure; (11) Fischer-Tropsch synthesis: The gas after fine desulfurization and pressurization is introduced into the Fischer-Tropsch synthesis system K. Under the conditions of 4-6 MPa gauge pressure and 160-200°C, hydrocarbon products are synthesized by catalysis. Solid wax and liquid hydrocarbons are separated by condensation, and the purge gas is recycled as fuel gas.

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