Adiabatic and isothermal conversion device and process matched with crushed coal pressurized gasification

Abstract

The invention discloses an adiabatic and isothermal conversion device and process matched with crushed coal pressurized gasification. Raw gas produced by smokeless lump coal through a crushed coal pressurized gasification technology is taken as a raw material; comprising a washing separator, a gas-gas heat exchanger, a purification furnace, an organic sulfur hydrolysis tower, a first conversion furnace, a medium-pressure waste heat recoverer, a second conversion furnace, a matched steam pocket, a low-pressure waste heat recoverer, a first separator, a boiler water preheater, a low-pressure waste heat recoverer, a second separator, a condensed water preheater, an ORC system, an air cooler, a third separator, a final cooler and an ammonia washing tower. The first conversion furnace is a radial heat insulation conversion furnace; and the second conversion furnace is a radial isothermal conversion furnace. According to the novel adiabatic and isothermal CO conversion process, the advantages of traditional adiabatic conversion and isothermal conversion are exerted in the conversion section of a smokeless lump coal and crushed coal pressurized gasification process adopted in coal gasification, the technological process is shortened, the system resistance is reduced, meanwhile, high-grade steam is produced as a byproduct, and stable, long-term and full-optimal operation of the system is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of raw coal gas conversion, and in particular to an "adiabatic + isothermal" conversion device and process supporting crushed coal pressurized gasification. Background Art

[0002] Coal gasification is a complex thermochemical conversion process in which coal reacts with a gasifying agent under high temperature and high pressure to produce CO, H2, and CH4 as the main components, and byproducts such as H2S, COS, NH3, and CO2. Coal gasification mainly includes fixed bed gasification, fluidized bed gasification, and entrained bed gasification. Each gasification technology has its own advantages and disadvantages. The selection of gasification process needs to be based on a comprehensive comparison of product requirements, raw coal types, technology maturity and reliability, investment, and other aspects.

[0003] Different gasification processes have their inherent characteristics, and different coal qualities have corresponding gasification processes. Crushed coal pressurized gasification process belongs to fixed bed gasification technology, which is often used as a gasification technology for producing city gas, methanol, and synthetic ammonia raw gas. This process is applicable to a wide range of coal types. Smokeless lump coal is an ideal raw material for crushed coal pressurized gasification process.

[0004] The crushed coal pressurized gasification involved in the present invention is reverse gasification. The gasifier is roughly divided into ash layer, oxidation layer, reduction layer, retorting layer and drying layer from bottom to top. The coal stays in the furnace for a long time, and the operating temperature in the furnace and the gas temperature at the furnace outlet are lower than other gasification processes. Raw coal gas usually contains impurities such as organic sulfur (such as COS, thiophene, mercaptan, sulfide, etc.), tar, phenol, naphthalene, dust, etc. In chemical production, these harmful substances need to be removed to meet the production needs of chemical processes. In the low-temperature methanol washing section, methanol has a large solubility in H2S and CS2, and a small solubility in organic sulfur. If the organic sulfur content in the raw coal gas is high and cannot be effectively converted in the conversion section, it will have a serious impact on the operation of the system.

[0005] The traditional crushed coal pressurized gasification process is transformed to use a three-stage adiabatic furnace: In view of the characteristics of the crushed coal pressurized gasification process, adiabatic conversion is generally selected as the conversion section when this gasification technology is used. When producing synthetic ammonia, three axial adiabatic conversion furnaces are required. Through multi-stage conversion, CO in the raw coal gas participates in the reaction to reduce the CO content in the outlet gas to below the process requirement of 0.8%. The main disadvantages of using the adiabatic conversion process are as follows: 1) The thermal insulation process is long, involves many pieces of equipment, has high system resistance, and requires large engineering investment.

[0006] 2) The CO conversion reaction is a reversible exothermic reaction. The chemical equilibrium is limited at high temperature, which is not conducive to moving in the positive reaction direction.

[0007] 3) The temperature of the catalyst bed in the conversion furnace is difficult to control and is prone to temperature spikes.

[0008] 4) The system has high energy consumption. The axial conversion furnace is used, and the large system pressure difference leads to increased energy consumption.

[0009] 5) The catalyst life is short. Under high temperature and high water vapor ratio reaction conditions, the catalyst activity decreases quickly and pulverizes quickly.

[0010] The novel "adiabatic + isothermal" CO conversion production process of the present invention takes advantage of traditional adiabatic conversion and isothermal conversion in the conversion section of the crushed coal pressurized gasification process, shortens the process flow, reduces system resistance, and produces high-grade steam as a by-product, thereby achieving safe, long-term, full and optimal operation of the system. Summary of the invention

[0011] Based on the above description, the present invention provides an "adiabatic + isothermal" conversion device and process for crushed coal pressurized gasification to solve the problems of the existing crushed coal pressurized gasification process conversion, the long adiabatic process flow, many equipments, large system resistance, and large engineering investment; the catalyst bed temperature of the conversion furnace is difficult to control and is prone to temperature rise; the system has high energy consumption, and an axial conversion furnace is used, and the large system pressure difference leads to increased energy consumption; the catalyst has a short life, a rapid decrease in activity, and a rapid pulverization.

[0012] The technical solution of the present invention to solve the above technical problems is as follows: An "adiabatic + isothermal" conversion device supporting crushed coal pressurized gasification, the raw material is the raw gas produced by the crushed coal pressurized gasification technology of smokeless lump coal, including an air cooler and a raw gas pretreatment system connected in sequence, a first conversion furnace, a medium-pressure waste heat recovery device, a second conversion furnace, a low-pressure waste heat recovery device, a first separator, a boiler water preheater, a low-low-pressure waste heat recovery device, a second separator, a condensate preheater, an ORC system, a third separator, a final cooler, and an ammonia washing tower, and the raw gas pretreatment system includes a washing separator, a gas-to-gas heat exchanger, and a purification furnace connected in sequence; The first conversion furnace is a radial adiabatic conversion furnace; The second conversion furnace is a radial isothermal conversion furnace; The raw coal gas pretreatment system further comprises an organic sulfur hydrolysis tower, which is arranged in parallel with the pipeline between the purification furnace and the first shift furnace. The air cooler is connected between the condensate preheater and the third separator, and is arranged in parallel with the ORC system.

[0013] Based on the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, the above-mentioned "adiabatic + isothermal" conversion device for pressurized gasification of crushed coal also includes a washing separator, a gas-to-gas heat exchanger, and a purification furnace connected in sequence. The discharge port of the purification furnace is connected to the feed port of the first conversion furnace, and the raw gas delivery pipeline from the gasification device is connected to the washing separator. The first conversion furnace has two gas outlets, including a first gas outlet and a second gas outlet. The first gas outlet is connected to the gas inlet of the gas-to-gas heat exchanger through a pipeline to heat the raw gas, and the second gas outlet is connected to the second conversion furnace after passing through the medium-pressure waste heat recovery device.

[0015] Furthermore, in the above-mentioned "adiabatic + isothermal" conversion device for crushed coal pressurized gasification, the gas-to-gas heat exchanger has two gas outlets, namely a third gas outlet and a fourth gas outlet, the third gas outlet is connected to the purification furnace, and the fourth gas outlet is connected to the second conversion furnace.

[0016] Furthermore, in the above-mentioned "adiabatic + isothermal" conversion device supporting crushed coal pressurized gasification, the radial adiabatic conversion furnace includes a shell and a full radial catalyst frame, and the full radial catalyst frame is composed of a gas distribution cylinder, a gas collecting cylinder, a flat cover, and a catalyst loading pipe. The shell is composed of an upper head, a lower head, a cylinder, a gas inlet short-circuit, a gas outlet short-circuit, and a catalyst loading port.

[0017] Furthermore, in the above-mentioned "adiabatic + isothermal" conversion device supporting crushed coal pressurized gasification, the radial isothermal conversion furnace is composed of a shell and internal parts, the shell is composed of a cylinder, an upper head, and a lower head, and the internal parts are composed of a water inlet spherical cavity, a water heat transfer tube bundle, a water collecting spherical cavity, a gas distribution cylinder, a sealing plate, a gas collecting cylinder, a collecting spherical shell, an outlet pipe and other components, and a spherical header structure is used between the water heat transfer tube bundle and the inlet and outlet water pipes. The radial distributor passes through the catalyst bed radially from the outside to the inside, and the heat exchange tube is buried in the catalyst bed.

[0018] A "adiabatic + isothermal" conversion process for pressurized gasification of crushed coal adopts the device described in any of the above items. The raw gas treated by the raw gas pretreatment system enters the first conversion furnace for conversion reaction. The outlet conversion gas is divided into two streams. One stream returns to the gas-to-gas heat exchanger to preheat the raw gas at the inlet of the purification furnace; the other stream enters the medium-pressure waste heat recovery device to produce saturated steam as a by-product. The gas after heat exchange in the gas-to-gas heat exchanger is combined with the outlet gas of the medium-pressure waste heat recovery device and enters the second conversion furnace.

[0019] Furthermore, the gas from the second conversion furnace passes through a low-pressure waste heat recovery device, and then the conversion gas condensate is separated in the first separator. The cooled conversion gas preheats the low-pressure boiler water in the boiler water preheater, and at the same time, the conversion gas temperature is reduced. The gas and liquid are separated at the bottom of the boiler water preheater, and the gas phase enters the low-pressure waste heat recovery device to produce saturated steam as a by-product. The conversion gas temperature continues to decrease, and the conversion gas condensate is separated in the second separator, and then enters the condensate preheater. The gas and liquid are separated at the bottom of the condensate preheater, and the conversion gas is cooled by the ORC system, and the conversion gas condensate is separated in the third separator, and is cooled with circulating water in the final cooler and then sent to the ammonia washing tower. After washing away the ammonia in the conversion gas, it is sent to the low-temperature methanol washing device.

[0020] Furthermore, the raw coal gas produced by the crushed coal pressurized gasification device of the fixed bed gasification technology enters the washing separator, and after washing to remove impurities such as dust entrained in the raw coal gas, the raw coal gas enters the gas-to-gas heat exchanger, and the raw coal gas is heated by utilizing the temperature of the conversion gas at the outlet of the first conversion furnace, and then enters the purification furnace, in which protective agents and deoxidizers are installed to remove substances harmful to the conversion catalyst and oxygen in the raw coal gas.

[0021] Furthermore, the CO content in the raw coal gas is 24-28% by volume. After passing through the first shift converter, the CO content in the shifted gas is reduced to 4-7%, and after passing through the second shift converter, it is reduced to below 0.8%.

[0022] Furthermore, the first conversion furnace adopts an adiabatic conversion furnace, in which the organic sulfur hydrogenation conversion rate reaches more than 98%, and the inorganic sulfur is removed in the subsequent low-temperature methanol washing section.

[0023] Furthermore, two purification furnaces are arranged in parallel to serve as backup for each other; Furthermore, in terms of volume percentage, the CO content in the raw coal gas is about 24~28%. After passing through the first conversion furnace, the CO in the conversion gas can be reduced to 4~7%. After passing through the second conversion furnace, it can be reduced to below 0.8%. Judging from the operating results of other devices, when the CO content at the inlet of the second conversion furnace increases to 13%, it can still be reduced to below 0.8% at the outlet after isothermal conversion.

[0024] Furthermore, since the raw coal gas contains H2S, COS, thiophene, mercaptan sulfide and other substances, they are permanently toxic to the catalyst of the synthetic ammonia system. Organic sulfur can be converted into inorganic sulfur under high temperature conditions, so the first conversion furnace adopts an adiabatic conversion furnace, and the organic sulfur hydrogenation conversion rate in the first conversion furnace can reach more than 98%. Inorganic sulfur is removed in the subsequent low-temperature methanol washing section.

[0025] This conversion process sets up an organic sulfur hydrolysis tower in a bypass manner, and can pass through the organic sulfur hydrolysis tower or not. If the sulfide content in the raw coal gas is too high, the high-content organic sulfur can be converted into inorganic sulfur by cutting into the organic sulfur hydrolysis tower, and the inorganic sulfur is removed in the subsequent low-temperature methanol washing section. When the raw coal is low-sulfur coal, the organic sulfur hydrolysis tower can be cut out, and it does not pass through the hydrolysis tower, and enters the conversion system after pretreatment.

[0026] Furthermore, the temperature of the raw gas after being treated by the raw gas pretreatment system is 230-245°C; Furthermore, the first shift converter is an adiabatic shift converter, and the outlet temperature is about 350-380°C. The temperature of the shift gas at the outlet of the first shift converter is used to heat the raw coal gas to 200-215°C before entering the purification furnace. Furthermore, the temperature of the converted gas is reduced to 160~165℃ through the low-pressure waste heat recovery device; Furthermore, the temperature of the shifted gas is reduced to 145~155°C through the boiler water preheater; Furthermore, the temperature of the converted gas is reduced to 110~120℃ through the low-pressure waste heat recovery device.

[0027] Furthermore, the conversion gas is recycled through the ORC system to generate electricity, reducing the conversion gas temperature to 80~85℃.

[0028] Furthermore, after passing through the final cooler, the converted gas is cooled to 35-40°C and then sent to the ammonia scrubbing tower.

[0029] Furthermore, the gas is converted through a medium-pressure waste heat recovery device to produce 4.1MPa saturated steam as a by-product.

[0030] Furthermore, the boiler water in the heat exchange tubes of the second shift furnace removes the by-product reaction heat and by-produces 1.2 MPa saturated steam.

[0031] Furthermore, the gas is converted through a low-pressure waste heat recovery device to produce 0.5MPa saturated steam as a by-product.

[0032] Furthermore, the gas is converted through a low-pressure waste heat recovery device to produce 0.1MPa saturated steam as a by-product.

[0033] The isothermal conversion furnace of the present invention is a radial structure, and the gas is collected from all sides to the central tube. In the process setting, the process is a series process of adiabatic first and isothermal second, and the CO content in the gas is lower than 0.8% through the conversion process. In the conversion "adiabatic + isothermal" process of the present invention, the raw coal gas is not divided into shares, but all the gas passes through the adiabatic furnace and the isothermal furnace in turn.

[0034] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: The present invention combines smokeless lump coal, crushed coal pressurized gasification technology, synthetic ammonia raw gas requirements and other conditions to develop an "adiabatic + isothermal" conversion process.

[0035] This "adiabatic + isothermal" conversion process is suitable for the conversion process flow of smokeless lump coal as raw material and gasification using crushed coal pressurized gasification technology. Compared with the traditional conversion process, it has the advantages of less process equipment, shorter process, low engineering investment, low operating energy consumption, convenient operation, high safety, fast start-up speed, good heat recovery effect and low consumption.

[0036] The tar content in the raw gas produced by the crushed coal pressurized gasification technology of smokeless lump coal is lower than that in the raw gas produced by other types of coal. This process can effectively solve the problem by setting up a raw gas pretreatment system. The coal dust in the raw gas is washed by the washing separator of the raw gas pretreatment system, and the trace tar existing can be cracked at high temperature under the high temperature conditions of the purification furnace and the first conversion furnace (adiabatic furnace), thereby avoiding the risk of tar blocking the system.

[0037] In this process, the first conversion furnace is a radial adiabatic conversion furnace. If a traditional axial conversion furnace is used, the gas passes through the conversion furnace axially, the gas flow path is long, the resistance is large, and the energy consumption is high. The gas reacts for a long time in the catalyst bed, the temperature is difficult to control, and it is not easy to operate, and it is easy to run away from the temperature. In a high temperature environment, the catalyst is prone to pulverization and gradual decrease in activity. The lifespan and replacement cycle of the catalysts in the first and second conversion furnaces are inconsistent, and the number of shutdowns and replacements is high. Considering the shortcomings of the axial adiabatic furnace, the adiabatic conversion furnace of the present invention adopts a radial type.

[0038] The gas entering the adiabatic converter passes through the shell and the gas distribution tube, and then through the catalyst loading tube and is collected in the central gas collecting tube before exiting the radial adiabatic converter. The gas after exiting the radial adiabatic converter enters the medium-pressure waste heat recovery device to recover waste heat and by-product steam. The by-product steam is fed into the system to participate in the conversion reaction in the second converter. Compared with the axial converter, the present invention adopts a radial furnace, the process gas passes through a large area of ​​the catalyst loading tube, the gas and catalyst contact time is short, the system resistance is low, the temperature is easy to control, and the operation is simple. When the production load is stable, the reaction temperature and hot spot temperature of the catalyst loading tube in the radial adiabatic converter are stable, the system resistance is small, and the catalyst life is long.

[0039] In this process, the second shift furnace is a radial isothermal shift furnace. When using crushed coal pressurized gasification technology, multiple adiabatic furnaces are usually connected in series after the first shift furnace to control the CO content at the outlet of the shift system below 0.8%. The CO shift reaction is a highly exothermic reaction. Removing the heat released by the reaction in time during the reaction is conducive to moving the balance toward the positive reaction direction, while ensuring the effect and service life of the catalyst.

[0040] The second shift converter adopts a radial isothermal shift converter. The gas enters the shift converter and passes through the catalyst bed radially from the outside to the inside through the gas distribution tube. The shift reaction heat is removed by the water heat transfer tube bundle buried in the catalyst bed and is collected by the internal gas collecting tube before leaving the shift converter. The water from the steam drum enters from the lower part of the radial isothermal shift converter and is distributed to the water heat transfer tube bundle through the water inlet spherical cavity. After heat exchange, it is collected by the upper water collecting spherical cavity and then leaves the radial isothermal shift converter to the steam drum.

[0041] Isothermal shift is often used in the deep shift process with high CO concentration in raw coal gas. The CO content in raw coal gas is about 24~28% by crushed coal pressurized gasification process. After the reaction in the first shift furnace, the CO content is below 4~7%. By controlling the outlet temperature and CO content of the first shift furnace, the temperature and CO content of the gas entering the second shift furnace (adiabatic furnace) are guaranteed, and the isothermal shift furnace operation requirements under low CO concentration process conditions can be achieved, while the CO content in the outlet gas of the second shift furnace meets the synthetic ammonia process requirements.

[0042] This conversion process sets up an organic sulfur hydrolysis tower in a bypass manner, and can pass through the organic sulfur hydrolysis tower or not. If the sulfide content in the raw coal gas is too high, the high-content organic sulfur can be converted into inorganic sulfur by cutting into the organic sulfur hydrolysis tower, and the inorganic sulfur is removed in the subsequent low-temperature methanol washing section. When the raw coal is low-sulfur coal, the organic sulfur hydrolysis tower can be cut out, and it does not pass through the hydrolysis tower, and enters the conversion system after pretreatment.

[0043] The conversion device and process of the present invention are provided with an organic sulfur hydrolysis tower, which has a wider adaptability to sulfur-containing coal types, and the device and process can meet the production requirements of high-sulfur and low-sulfur raw coal. By setting up an ORC system, the waste heat of low-grade energy of the device can be used to generate electricity, thereby improving economic benefits and reducing production costs. The organic sulfur hydrolysis tower and the air cooler are both arranged in parallel, which are flexible to operate and can be switched at any time under different working conditions. The organic sulfur hydrolysis tower is arranged in parallel on the pipeline between the purification furnace and the first conversion furnace, and can be switched freely according to production needs. The air cooler is arranged between the condensate preheater and the third separator, and is arranged in parallel with the ORC system. When the ORC system operates abnormally, it can be freely switched to the air cooler.

[0044] The present invention provides a method of using raw coal gas produced by crushed coal pressurized fixed bed gasification method of smokeless lump coal as raw material, and reducing CO in the raw coal gas to the required content level of process gas through a conversion reaction through a novel "adiabatic + isothermal" CO sulfur-resistant conversion process. The process takes advantage of traditional adiabatic conversion and isothermal conversion, shortens the process flow, reduces equipment investment, reduces system resistance, and produces high-grade steam as a by-product, thereby achieving stable, long-term, full and optimal operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1A process flow chart of an "adiabatic + isothermal" conversion device for pressurized gasification of crushed coal provided in an embodiment of the present invention.

[0046] In the accompanying drawings, the components represented by the reference numerals are listed as follows: 1. Washing separator; 2. Gas-to-gas heat exchanger; 3. Purification furnace; 4. First conversion furnace; 5. Medium-pressure waste heat recovery device; 6. Second conversion furnace; 7. Low-pressure waste heat recovery device; 8. First separator; 9. Boiler water preheater; 10. Low-pressure waste heat recovery device; 11. Second separator; 12. Condensate preheater; 13. ORC system; 14. Third separator; 15. Final cooler; 16. Ammonia washing tower; 17. Organic sulfur hydrolysis tower; 18. Air cooler. DETAILED DESCRIPTION

[0047] In order to facilitate understanding of the present application, the present application will be described more comprehensively below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0049] It should be noted that when an element is considered to be “connected to” another element, it can be directly connected to the other element or connected to the other element through an intervening element.

[0050] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0051] Selection of crushed coal pressurized gasification conversion process: crushed coal pressurized gasification process is adopted, and the conversion stage mostly adopts adiabatic conversion process. Due to the inherent characteristics of the adiabatic conversion process, the following situations may occur: 1. The CO conversion reaction is a highly exothermic reaction, and the bed temperature rises. A graded reaction is required, and a heat exchanger is required at the inlet of each bed level for cooling, resulting in a long process, more equipment, difficult operation, and high system resistance, which increases the project investment. 2. The increase in the bed temperature of the adiabatic conversion reaction means that a large amount of steam needs to be added, the heat load increases, and the subsequent circulating water consumption increases, resulting in high overall energy consumption. 3. The high temperature rise and high water-vapor ratio of the adiabatic conversion will aggravate the corrosion of the equipment, reduce the activity of the catalyst, reduce the conversion rate, and shorten the catalyst life cycle and require frequent replacement.

[0052] The gas composition of the crushed coal pressurized gasification process is different from that of other gasification methods: (1) The raw coal gas has a high water vapor content; water vapor accounts for about 1 / 3 of the raw coal gas, and the rest is coal gas; (2) The raw coal gas has a high dust content; (3) The raw coal gas contains substances such as tar; (4) The raw coal gas contains organic sulfur substances.

[0053] Gas composition of different gasification methods:

[0054] System blockage: In the crushed coal pressurized gasification technology, due to the characteristics of gasification, tar will be produced in the generated raw coal gas. The tar and coal dust in the coal gas will accumulate in the system, which may cause equipment blockage and affect the long-term operation of the equipment.

[0055] Aiming at the problems that are prone to occur when adiabatic transformation is used in the transformation stage of the crushed coal pressurized gasification process, the CO "adiabatic + isothermal" transformation process was invented, which can effectively solve the problems caused by adiabatic transformation.

[0056] Invented the CO "adiabatic + isothermal" process Example 1 A "adiabatic + isothermal" conversion device supporting crushed coal pressurized gasification, the raw material is the raw gas produced by the crushed coal pressurized fixed bed gasification method, including an air cooler 18 and a raw gas pretreatment system connected in sequence, a first conversion furnace 4, a medium-pressure waste heat recovery device 5, a second conversion furnace 6, a low-pressure waste heat recovery device 7, a first separator 8, a boiler water preheater 9, a low-low-pressure waste heat recovery device 10, a second separator 11, a condensate preheater 12, an ORC system 13, a third separator 14, a final cooler 15, and an ammonia washing tower 16, the raw gas pretreatment system includes a washing separator 1, a gas-to-gas heat exchanger 2, a purification furnace 3, and an organic sulfur hydrolysis tower 17, and the purification furnace is connected to the first conversion furnace 4; The first conversion furnace 4 is a radial adiabatic conversion furnace; The second conversion furnace 6 is a radial isothermal conversion furnace; The organic sulfur hydrolysis tower 17 is connected in parallel with the pipeline between the purification furnace 3 and the first shift furnace 4 .

[0057] The air cooler 18 is connected between the condensate preheater 12 and the third separator 14 , and is arranged in parallel with the ORC system 13 .

[0058] In the present embodiment, as a further improvement, the above-mentioned "adiabatic + isothermal" conversion device for supporting crushed coal pressurized gasification, the discharge port of the purification furnace 3 is connected to the feed port of the first conversion furnace 4, the raw gas delivery pipeline from the smokeless lump coal fixed bed gasification is connected to the washing separator 1, the first conversion furnace 4 has two gas outlets, including a first gas outlet and a second gas outlet, the first gas outlet is connected to the gas inlet of the gas-to-gas heat exchanger 2 through a pipeline to heat the raw gas, and the second gas outlet is connected to the second conversion furnace 6 after passing through the medium-pressure waste heat recovery device 5.

[0059] In this embodiment, further, the gas-to-gas heat exchanger 2 has two gas outlets, namely a third gas outlet and a fourth gas outlet. The third gas outlet is connected to the purification furnace 3 , and the fourth gas outlet is connected to the second conversion furnace 6 .

[0060] In this embodiment, further, the radial adiabatic conversion furnace includes a shell and a full radial catalyst frame, the full radial catalyst frame is composed of a gas distribution cylinder, a gas collecting cylinder, a flat cover, and a catalyst loading pipe. The shell is composed of an upper head, a lower head, a cylinder, a gas inlet short-circuit, a gas outlet short-circuit, and a catalyst loading port.

[0061] In this embodiment, further, the radial isothermal conversion furnace is composed of a shell and internal parts, the shell is composed of a cylinder, an upper head, and a lower head, and the internal parts are composed of a water inlet spherical cavity, a water heat transfer tube bundle, a water collecting spherical cavity, a gas distribution cylinder, a sealing plate, a gas collecting cylinder, a collecting spherical shell, an outlet pipe and other components, and a spherical header structure is used between the water heat transfer tube bundle and the inlet and outlet water pipes. The gas passes through the catalyst bed layer radially from the outside to the inside along the multiple vents on the side wall of the gas distribution cylinder, and the water heat transfer tube bundle is buried in the catalyst bed layer.

[0062] In the crushed coal pressurized gasification process using fixed bed gasification method, the CO content in the raw coal gas is about 24~28% by volume. After passing through the first conversion furnace reaction, the CO content is below 4~7%.

[0063] Example 2 A "adiabatic + isothermal" conversion process with crushed coal pressurized gasification, the raw coal gas produced by the crushed coal pressurized gasification device using fixed bed gasification technology enters the washing separator 1, and the raw coal gas enters the gas-to-gas heat exchanger 2 after being washed with recycled water from the gasification and purification device to remove impurities such as dust entrained in the raw coal gas, and enters the purification furnace 3 after being heated to 200-215°C using the temperature of the conversion gas at the outlet of the first conversion furnace 4. The purification furnace 3 is equipped with a protective agent and a deoxidizer, the function of the protective agent is to remove impurities that are harmful to the sulfur-resistant conversion catalyst in the conversion furnace; the function of the deoxidizer is to remove oxygen from the raw coal gas, and the oxygen content at the outlet of the purification furnace is required to be ≤100ppm. The crushed coal pressurized gasification device is a pre-installed device of this process, an external device, and one of the existing technologies can be used.

[0064] The temperature of the raw gas after being treated by the raw gas pretreatment system is 233°C, and it enters the first conversion furnace 4 for conversion reaction. The first conversion furnace 4 is an adiabatic conversion furnace, and the outlet temperature is about 367°C. The outlet conversion gas is divided into two streams, one of which is returned to the gas-to-gas heat exchanger 2 to preheat the raw gas at the inlet of the purification furnace 3; the other stream enters the medium-pressure waste heat recovery device 5 to produce 4.1MPa saturated steam as a by-product. The gas after heat exchange from the gas-to-gas heat exchanger 2 is combined with the outlet gas of the medium-pressure waste heat recovery device 5 and enters the second conversion furnace 6. The second conversion furnace 6 is an isothermal conversion furnace, and heat exchange tubes are buried between the catalyst beds. The boiler water in the heat exchange tubes removes the by-product reaction heat and produces 1.2MPa saturated steam as a by-product.

[0065] The gas from the second shift furnace 6 is passed through the low-pressure waste heat recovery device 7 to produce 0.5MPa saturated steam as a by-product, and the temperature of the shifted gas is reduced to 165°C, and then the shifted gas condensate is separated in the first separator 8. The shifted gas after cooling preheats the low-pressure boiler water to 150°C in the boiler water preheater 9, and the temperature of the shifted gas is reduced to 155°C. The gas and liquid are separated at the bottom of the boiler water preheater 9, and the gas phase enters the low-pressure waste heat recovery device 10 to produce 0.1MPa saturated steam as a by-product, and the temperature of the shifted gas is reduced to 120°C. The shifted gas condensate is separated in the second separator 11, and then enters the condensate preheater. The gas and liquid are separated at the bottom of the condensate preheater. The shifted gas is further cooled by the ORC system 13, and the shifted gas recovers heat energy through the ORC system to generate electricity, and the temperature of the shifted gas is reduced to 80~85°C. The shifted gas condensate is separated in the third separator 14, and is sent to the ammonia washing tower 16 after being cooled to 40°C with circulating water in the final cooler 15. After washing away ammonia in the conversion gas, it is sent to a low-temperature methanol washing device. The low-temperature methanol washing device is an external device and can be any one of the existing technologies.

[0066] Because the raw coal gas from the crushed coal pressurized gasification process contains substances such as H2S, COS, thiophene, and mercaptan sulfide, they are poisonous to the catalyst of the synthetic ammonia system and are permanently toxic. Organic sulfur can be converted into inorganic sulfur under high temperature conditions, so the first conversion furnace 4 adopts an adiabatic conversion furnace, and the organic sulfur hydrogenation conversion rate in the first conversion furnace 4 can reach more than 98%. At the same time, an organic sulfur hydrolysis tower is set. When the organic sulfur content in the raw coal gas is high, it can be switched to the organic sulfur hydrolysis tower, and the operation is more flexible for different working conditions. Inorganic sulfur is removed in the subsequent low-temperature methanol washing section. The synthetic ammonia system is a subsequent process of this process, and one of the existing technologies can be used.

[0067] In terms of volume percentage, the CO content in the raw coal gas of the crushed coal pressurized gasification process is about 24-28%. After passing through the first conversion furnace 4, the CO in the conversion gas can be reduced to 7%, and after reacting through the second conversion furnace 6, it can be reduced to below 0.8%. Judging from the operating results of other devices, when the CO content at the inlet of the second conversion furnace 6 increases to 13%, the outlet can still be reduced to below 0.8% after isothermal conversion.

[0068] In the second conversion furnace 6, i.e., the isothermal conversion furnace, heat is removed through the water heat transfer tube bundle buried in the catalyst bed to produce steam by-products, which has an outstanding energy-saving effect. At the same time, the catalyst bed temperature is easy to control and will not be overheated, which can effectively extend the service life of the catalyst. When the catalyst activity of the first conversion furnace 4 decreases and the outlet CO content increases, the CO index can still be controlled through the second conversion furnace 6, i.e., the isothermal conversion furnace. This process setting can extend the service life of the catalyst in the first conversion furnace, and the catalyst can be replaced synchronously when the catalyst activity of the second conversion furnace decreases, reducing the cost of replacing the catalyst while achieving long-term operation of the system.

[0069] The first conversion furnace 4 (adiabatic conversion furnace) adopts a radial reactor, which can achieve the goals of small equipment diameter, small system resistance, convenient catalyst loading, and low investment.

[0070] In the process flow, a washing separator 1 is set to wash and remove impurities such as dust entrained in the raw coal gas, and two purification furnaces 3 (mutually standby) are set. The purification furnace 3 is equipped with a protective agent and a deoxidizer, and a pre-conversion reaction occurs here to remove substances harmful to the conversion catalyst and oxygen in the raw coal gas. The pretreatment of the washing separator 1 and the purification furnace 3 can ensure the quality of the raw coal gas entering the conversion device, remove dust, impurities and harmful components, and reduce the clogging of equipment, heat exchangers, distributors, and catalyst pores.

[0071] The present invention adds an organic sulfur hydrolysis tower. If the organic sulfur content in the raw coal gas is high, it can be cut into the organic sulfur hydrolysis tower for treatment before entering the conversion system. The operation is more flexible under different organic sulfur content conditions, and the stable operation of the system can be guaranteed.

[0072] The present invention adds an ORC system, and the conversion gas is recycled through the ORC system to generate electricity. The low-grade energy waste heat of the device can be used to generate electricity, thereby improving economic benefits and reducing production costs. At the same time, an air cooler is set in parallel. When the ORC system operates abnormally, switching can ensure the stable operation of the system.

[0073] The tar content in the raw gas produced by the crushed coal pressurized gasification technology of smokeless lump coal is lower than that in the raw gas produced by other types of coal. This process can effectively solve the problem by setting up a raw gas pretreatment system. The coal dust in the raw gas is washed by the washing separator of the raw gas pretreatment system, and the trace tar existing can be cracked at high temperature under the high temperature conditions of the purification furnace and the first conversion furnace (adiabatic furnace), thereby avoiding the risk of tar blocking the system.

[0074] The conversion process mainly recovers the heat in the conversion gas in the form of by-product steam, heating boiler water and condensate to achieve cascade utilization of energy. The process recovers the heat in the conversion gas to produce 4.1MPa, 1.2MPa, 0.5MPa, and 0.1MPa grade saturated steam by-products. The outlet gas of the first conversion furnace (adiabatic furnace) enters the medium-pressure waste heat recovery device to produce 4.1MPa saturated steam by-product. Part of the by-product steam is fed into the system and enters the second conversion furnace (isothermal furnace) to participate in the conversion reaction, and the other part is fed into the steam pipe network. The second conversion furnace (isothermal furnace) removes the system reaction heat and produces 1.2MPa saturated steam by-product. The gas out of the conversion furnace enters the low-pressure waste heat recovery device and the low-low-pressure waste heat recovery device successively to produce 0.5MPa and 0.1MPa grade saturated steam by-products. At the same time, heat is recovered by heating boiler water and condensate.

[0075] The conversion process sets up an ORC system, which can use the low-grade waste heat of the process gas to generate electricity, reduce the process gas temperature at the outlet of the condensate preheater from 115-110℃ to 80℃, and switch to an air cooler to cool the process gas when the ORC system is abnormal.

[0076] Compared with other forms of heat recovery, this process produces 0.1MPa saturated steam as a by-product. The 0.1MPa saturated steam produced by this process is used for power generation.

[0077] The process has been applied in the 550,000-ton ammonia-alcohol project, and the device is running economically and stably. The CO content at the system outlet is less than 0.8%, the pressure difference of the converter is less than 20KPa, and no coal dust, tar or other substances have been found to block the system. The system produces 93.14 tons of saturated steam of different pressure levels, including 19.76 tons of 4.0MPa steam, 32.01 tons of 1.2MPa steam, 10.4 tons of 0.5MPa steam, and 30.98 tons of 0.1MPa steam. 1.2MPa, 0.5MPa, and 0.1MPa steam are incorporated into the pipeline network for power generation.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A "adiabatic + isothermal" conversion device for pressurized gasification of crushed coal, characterized in that: The raw material is a raw gas produced by crushed coal pressurized gasification technology using smokeless lump coal as raw material, comprising an air cooler (18) and a raw gas pretreatment system, a first shift furnace (4), a medium-pressure waste heat recovery device (5), a second shift furnace (6), a low-pressure waste heat recovery device (7), a first separator (8), a boiler water preheater (9), a low-pressure waste heat recovery device (10), a second separator (11), a condensate preheater (12), an ORC system (13), a third separator (14), a final cooler (15), and an ammonia washing tower (16), wherein the raw gas pretreatment system comprises a washing separator (1), a gas-to-gas heat exchanger (2), a purification furnace (3), and an organic sulfur hydrolysis tower (17) which are connected in sequence, and the purification furnace is connected to the first shift furnace (4); The first conversion furnace (4) is a radial adiabatic conversion furnace; The second conversion furnace (6) is a radial isothermal conversion furnace; The organic sulfur hydrolysis tower (17) is arranged in parallel with the pipeline between the purification furnace (3) and the first conversion furnace (4); The air cooler (18) is connected between the condensate preheater (12) and the third separator (14), and is arranged in parallel with the ORC system (13).

2. The "adiabatic + isothermal" conversion device for crushed coal pressurized gasification according to claim 1 is characterized in that: The discharge port of the purification furnace (3) is connected to the feed port of the first conversion furnace (4); the raw coal gas delivery pipeline from the gasification device is connected to the washing separator (1); the first conversion furnace (4) has two gas outlets, including a first gas outlet and a second gas outlet; the first gas outlet is connected to the gas inlet of the gas-to-gas heat exchanger (2) through a pipeline to heat the raw coal gas; the second gas outlet is connected to the second conversion furnace (6) after passing through the medium-pressure waste heat recovery device (5); The gas-to-gas heat exchanger (2) has two gas outlets, namely a third gas outlet and a fourth gas outlet, the third gas outlet is connected to the purification furnace (3), and the fourth gas outlet is connected to the second conversion furnace (6).

3. The "adiabatic + isothermal" conversion device for crushed coal pressurized gasification according to claim 1 is characterized in that: The radial adiabatic conversion furnace comprises a shell and a full radial catalyst frame, the full radial catalyst frame is composed of a gas distribution cylinder, a gas collecting cylinder, a flat cover, and a catalyst filling pipe, and the shell is composed of an upper head, a lower head, a cylinder, a gas inlet short-circuit, a gas outlet short-circuit, and a catalyst filling port; The radial isothermal conversion furnace is composed of a shell and internal parts. The shell is composed of a cylinder, an upper head and a lower head. The internal parts are composed of a water inlet spherical cavity, a water heat transfer tube bundle, a water collecting spherical cavity, a gas distribution tube, a sealing plate, a gas collecting tube, a collecting spherical shell and an outlet pipe. A spherical header structure is adopted between the water heat transfer tube bundle and the water inlet and outlet pipes.

4. A "adiabatic + isothermal" conversion process for pressurized gasification of crushed coal, characterized in that: By using the device described in any one of claims 1 to 3, the raw coal gas treated by the raw coal gas pretreatment system enters the first shift furnace (4) for shift reaction, and the outlet shift gas is divided into two streams, one of which is returned to the gas-to-gas heat exchanger (2) to preheat the raw coal gas at the inlet of the purification furnace (3); the other stream enters the medium-pressure waste heat recovery device (5) to produce saturated steam as a by-product, and the gas after heat exchange from the gas-to-gas heat exchanger (2) is combined with the outlet gas of the medium-pressure waste heat recovery device (5) and enters the second shift furnace (6).

5. The "adiabatic + isothermal" conversion process for crushed coal pressurized gasification according to claim 4 is characterized in that: The gas from the second conversion furnace (6) passes through a low-pressure waste heat recovery device (7), and then the conversion gas condensate is separated in a first separator (8). The conversion gas after cooling preheats the low-pressure boiler water in a boiler water preheater (9), and the conversion gas temperature is reduced at the same time. The gas and liquid are separated at the bottom of the boiler water preheater (9), and the gas phase enters a low-pressure waste heat recovery device (10) to produce saturated steam as a by-product. The conversion gas temperature continues to decrease, and the conversion gas condensate is separated in a second separator (11). Then, the gas enters a condensate preheater, and the gas and liquid are separated at the bottom of the condensate preheater. The conversion gas continues to be cooled through an air cooler (13), and the conversion gas condensate is separated in a third separator (14). The gas and gas condensate is cooled with circulating water in a final cooler (15) and then sent to an ammonia washing tower (16). After the ammonia in the conversion gas is washed away, the gas is sent to a low-temperature methanol washing device.

6. The "adiabatic + isothermal" conversion process for crushed coal pressurized gasification according to claim 5 is characterized in that: The raw coal gas generated by the crushed coal pressurized gasification device of the fixed bed gasification technology enters the scrubbing separator (1), and after the dust entrained in the raw coal gas is scrubbed and removed, the raw coal gas enters the gas-to-gas heat exchanger (2). The raw coal gas is heated by utilizing the temperature of the conversion gas at the outlet of the first conversion furnace (4), and then enters the purification furnace (3). The purification furnace (3) is equipped with a protective agent and a deoxidizer to remove substances harmful to the conversion catalyst and oxygen in the raw coal gas.

7. The "adiabatic + isothermal" conversion process for crushed coal pressurized gasification according to claim 6 is characterized in that: The first conversion furnace (4) adopts an adiabatic conversion furnace. The organic sulfur hydrogenation conversion rate in the first conversion furnace (4) reaches more than 98%, and the inorganic sulfur is removed in the subsequent low-temperature methanol washing section.

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