阅读说明：本技术 一种合成气的脱硫工艺 (Desulfurization process of synthesis gas ) 是由 马倩 潘建波 *** 邱一鑫 熊德芳 吕彬峰 于 2019-11-27 设计创作，主要内容包括：本发明公开一种合成气的脱硫工艺,包括第一湿法脱硫工艺和净化工艺,合成气依次经过第一湿法脱硫工艺和净化工艺,净化工艺为粗脱硫气流经第二脱硫装置,第二脱硫装置包括有一级加氢转化器和二级加氢转化器,一级加氢转化器装载有包括铁钼催化剂,二级加氢转化器装载有包括镍钼催化剂,粗脱硫气流经一级加氢转化器后流经二级加氢转化器,第二脱硫装置还装载有包括氧化锌的脱硫剂,将粗脱硫气中的硫化氢脱除,得到净化气。本发明的脱硫工艺,通过将合成气的硫化氢脱除到含量低于0.1ppm,从而保证后续煤加工工艺的顺利进行,充分利用了低阶煤中宝贵的挥发分和煤质；本发明中的脱硫工艺,运行成本较低,适合工业化生产。(The invention discloses a desulfurization process of synthesis gas, which comprises a first wet desulfurization process and a purification process, wherein the synthesis gas sequentially passes through the first wet desulfurization process and the purification process, the purification process is that crude desulfurization gas flows through a second desulfurization device, the second desulfurization device comprises a first-stage hydrogenation converter and a second-stage hydrogenation converter, the first-stage hydrogenation converter is loaded with a catalyst comprising iron and molybdenum, the second-stage hydrogenation converter is loaded with a catalyst comprising nickel and molybdenum, the crude desulfurization gas flows through the first-stage hydrogenation converter and then flows through the second-stage hydrogenation converter, and the second desulfurization device is also loaded with a desulfurizer comprising zinc oxide, and hydrogen sulfide in the crude desulfurization gas is removed to obtain purified gas. According to the desulfurization process, hydrogen sulfide in the synthesis gas is removed to a content of less than 0.1ppm, so that smooth proceeding of a subsequent coal processing process is ensured, and precious volatile components and coal quality in low-rank coal are fully utilized; the desulfurization process disclosed by the invention is low in operation cost and suitable for industrial production.)

1. The desulfurization process of the synthesis gas is characterized by comprising a first wet desulfurization process and a purification process, wherein the synthesis gas sequentially passes through the first wet desulfurization process and the purification process, the first wet desulfurization process is that the synthesis gas enters from the bottom of a first desulfurization device and is in countercurrent contact with a first desulfurization solution sprayed from the top of the first desulfurization device to remove hydrogen sulfide in the synthesis gas, and then the synthesis gas flows through a first gas-liquid separation device to be separated to obtain a crude desulfurization gas; the purification technology does the coarse desulfurization gas flows through second desulphurization unit, second desulphurization unit is including one-level hydroconversion ware and second grade hydroconversion ware, one-level hydroconversion ware loading includes the iron molybdenum catalyst, second grade hydroconversion ware loading includes the nickel molybdenum catalyst, the coarse desulfurization gas flows through behind the one-level hydroconversion ware flow through second grade hydroconversion ware, second desulphurization unit still loading includes the desulfurizer of zinc oxide, will hydrogen sulfide desorption in the coarse desulfurization gas obtains the purified gas.

2. The desulfurization process of claim 1, wherein the second desulfurization device is provided with a resistance wire comprising chromium and nickel, and the crude desulfurization gas flows through the resistance wire, so that H in the crude desulfurization gas₂S, ionizing into elemental sulfur.

3. The desulfurization process according to claim 1, further comprising a second wet desulfurization process of passing the purified gas through a third desulfurization unit, entering from the bottom of the third desulfurization unit, and contacting a second desulfurization solution sprayed from the top of the third desulfurization unit in a counter-current manner to remove hydrogen sulfide from the purified gas.

4. The desulfurization process according to claim 1, wherein the second desulfurization device is loaded with an electrode, and a direct current voltage higher than 10KV is applied to the electrode, so that H in the raw desulfurization gas is generated₂S, ionizing into elemental sulfur.

5. The desulfurization process of claim 1, wherein said first desulfurization solution comprises a PDS catalyst and said second desulfurization solution comprises an NHD solvent.

6. The desulfurization process of claim 1, wherein the syngas is pressurized to 20 to 100kPa by a first compression device before entering the first desulfurization device.

7. The desulfurization process of claim 1, wherein the crude desulfurization gas is pressurized to 1.0MPa to 3.0MPa by the second compression device before flowing into the second desulfurization device.

8. The desulfurization process of claim 7, wherein said second compression device comprises at least two compression apparatuses in series.

9. The desulfurization process according to claim 1 or 7, wherein the crude desulfurization gas is passed through an adsorption device loaded with an adsorption material comprising activated carbon before flowing into the second desulfurization device.

10. The desulfurization process of claim 1, wherein the cleaned gas is subjected to a shift process before passing through a third desulfurization unit.

Technical Field

The invention relates to the technical field of clean utilization of coal substances, in particular to a process for desulfurizing synthesis gas.

Background

More than half of the coal reserves already explored in China are low-rank coals, and the volatile components in the low-rank coals are equivalent to 1000 hundred million tons of oil and gas resources. The low-rank coal mainly has the characteristics of high moisture and high volatility, flame is long and has smoke during combustion, the coalification degree is low, and typical coal types are brown coal and long flame coal. The coal-rich, oil-less and gas-deficient coal in China becomes a major subject of the clean coal technology at present by how to efficiently utilize low-rank coal. However, both combustion power generation and modern coal chemical utilization have extremely low comprehensive utilization efficiency due to the three characteristics of high water content, high ash content and low calorific value.

At present, the utilization mode of low-rank coal is mainly direct combustion or gasification. Direct combustion power generation is one of the most common utilization modes, and more than 90% of lignite in China is used for power station boilers and various industrial boilers according to incomplete statistics. The direct combustion of the low-rank coal not only wastes rich oil and gas resources contained in the coal, has low efficiency, but also pollutes the environment, easily causes a large amount of greenhouse gases such as SOx and NOx, and causes severe weather environments such as acid rain. The modern coal chemical technology uses coal gasification as a technical tap, and primary raw materials CO and H required by chemical synthesis are obtained by gasification₂However, the coal gasification technology has not developed to date, and a mature large-scale commercial low-rank coal gasification technology has not yet been formed. In the prior art, low-rank coal gasification is used for preparing CO and H₂Generally, low-rank coal is pyrolyzed to obtain raw coal gas and upgraded coal, and the pyrolysis is generally carried out in the presence of a large amount of oxygen (or air), wherein a part of coal is reacted with oxygen to supply heat and generate a large amount of CO₂. Due to CO₂The gas can not be combusted, belongs to invalid gas, and because of aerobic combustion, the nitrogen content in the crude gas is too high, so that the energy density of the crude gas is reduced; and the crude gas contains a large amount of CH₄Reducing CO and H in the synthesis gas₂The content of (b) reduces the calorific value of the crude gas, the crude gas cannot be used as a primary raw material for chemical synthesis, and the mixed gas produced by pyrolysis has no other economic value except for the return combustionThe utilization rate of the coal raw material is low; and no related integrated equipment can utilize low-rank coal to continuously produce gas and can realize continuous large-scale production.

The methane synthesis reaction mainly involved in the production of synthetic natural gas by using coke oven gas or coal-derived synthetic gas is a strong exothermic reaction, 1% of CO in raw material gas reacts, and the temperature rise of the gas can reach 72 ℃; 1% CO2 reacts, and the gas temperature rises to 60 ℃. Therefore, the contents of CO and CO2 in the raw material gas must be strictly controlled within the specified process index range so as to avoid sintering and deactivation of the catalyst. In addition, the methane synthesis catalyst has good activity and high selectivity, is sensitive to poison and easy to be poisoned and inactivated, wherein the poisoning of sulfide is the most serious.

Usually most of H in coke oven gas or coal-made synthesis gas₂S is removed in the wet desulfurization process, while organic sulfur in the form of carbonyl sulfide, mercaptans, sulfides, thiophenes, etc. needs to be removed after conversion to inorganic sulfur.

The process for removing organic sulfur is generally: hydrogenolysis of organic sulfur to inorganic sulfur H by hydroconversion₂S, desulfurizing with adsorbent such as zinc oxide, activated carbon, iron oxide, molecular sieve, etc. The hydrogenolysis reaction of organic sulfur is exemplified as follows:

COS+H₂→CO+H₂S

C₂H₅SH+H₂→C₂H₆+H₂S

CH₃SC₂H₅+2H₂→CH₄+C₂H₆+H₂S

C₄H₄S+4H₂→C₄H₁₀+H₂S

the prior methods can remove the sulfur content to a lower degree, but have the defects of complex process, high equipment investment, long driving investment time and poor environmental protection.

Disclosure of Invention

In view of the above, the present invention aims to overcome the defects of the prior art and provide a process for desulfurizing synthesis gas by using synthesis gas in an oxygen-free or micro-oxygen-free conditionThe dried low-rank coal is prepared to contain CO and H₂The synthesis gas is subjected to wet desulphurization technology and purification technology to remove hydrogen sulfide in the synthesis gas, so that the low-rank coal is fully and effectively utilized.

In order to solve the technical problems, the invention provides the following technical scheme:

the desulfurization process of the synthesis gas comprises a first wet desulfurization process and a purification process, wherein the synthesis gas sequentially passes through the first wet desulfurization process and the purification process, the first wet desulfurization process is that the synthesis gas enters from the bottom of a first desulfurization device and is in countercurrent contact with a first desulfurization solution sprayed from the top of the first desulfurization device, hydrogen sulfide in the synthesis gas is removed, and then the synthesis gas flows through a first gas-liquid separation device and is separated to obtain a crude desulfurization gas; the purification technology does the coarse desulfurization gas flows through second desulphurization unit, second desulphurization unit is including one-level hydroconversion ware and second grade hydroconversion ware, one-level hydroconversion ware loading includes the iron molybdenum catalyst, second grade hydroconversion ware loading includes the nickel molybdenum catalyst, the coarse desulfurization gas flows through behind the one-level hydroconversion ware flow through second grade hydroconversion ware, second desulphurization unit still loading includes the desulfurizer of zinc oxide, will hydrogen sulfide desorption in the coarse desulfurization gas obtains the purified gas.

The raw material low-rank coal can be pulverized coal or lump coal, and when the low-rank coal adopts the lump coal, the pulverized coal with smaller granularity can be obtained by crushing and screening the oversize lump coal. The low-rank coal dried by the drying process enters the gasification reduction process for reaction, and for one-step optimization process, a gasification feeding process can be added before the dried low-rank coal enters the gasification reduction process, so that the dried low-rank coal can rapidly enter the gasification reduction process, the surface area of the material is increased, and the gasification reduction reaction can be accelerated.

Wherein, the gasification reduction process is a chemical reaction process for heating the dried low-rank coal under the condition of no oxygen or micro oxygen. The dried low-rank coal enters a gasification reduction process, and under the heating of heating media such as flue gas and the like, additives and the like do not need to be added in the reaction processAnd other substances are subjected to a complex chemical reaction process at the temperature of 350-800 ℃ and the pressure of less than or equal to 30Kpa to obtain solid carbon and high-temperature rich gas, wherein the solid carbon is upgraded coal, and the volatile components in the upgraded coal are 8-15 wt%. The high-temperature rich gas comprises CO and H₂、CO₂Hydrocarbon, coal tar, naphthalene, halide, dust, sulfur compounds, and the like.

The sulfur compounds are liable to cause poisoning and deactivation of the reforming conversion catalyst and the methane synthesis catalyst, so that the sulfur compounds in the purified rich gas need to be removed before the reforming conversion process. The purified rich gas enters a coarse desulfurization process for treatment, and H in the purified rich gas is removed₂S removal to 20mg/Nm³The following. The coarse desulfurization process adopts wet coarse desulfurization, the wet flue gas desulfurization technology is a gas-liquid reaction, the reaction speed is high, the desulfurization efficiency is high and generally higher than 90%, the technology is mature, and the application range is wide. The wet desulphurization technology is mature, the production operation is safe and reliable, and the wet desulphurization technology always occupies the dominant position in a plurality of desulphurization technologies, and accounts for more than 80 percent of the total installed capacity of desulphurization. Therefore, the wet desulphurization firstly removes a large amount of H in the rich gas₂And (4) removing the S.

By adopting a wet-process crude desulfurization process, common equipment cannot be operated under certain pressure, so that the air flow which is not compressed and flows is large, and the occupied area of the equipment and the whole set of equipment are large. And the total sulfur content of the gas after the crude desulfurization can not meet the requirements of the subsequent reforming conversion catalyst and the methane synthesis catalyst on the sulfur content. Therefore, the gas treated by the coarse desulfurization process is treated by a first compression process to improve the gas pressure, and then enters a fine desulfurization process, wherein the pressure of the first compression process is 20-25kg, and the temperature is 300-400 ℃. The fine desulfurization process is generally dry desulfurization, can be operated under certain pressure, increases the effective components of sulfur in unit volume of treatment, greatly improves the removal rate of sulfur content, greatly reduces a fine desulfurization device, and improves the utilization rate of equipment.

Therefore, the purification process of the present invention adopts a dry process, thereby combining a wet process and a dry process.

In the inventionIn the wet process, preferably, the first desulfurization solution contains a PDS catalyst, and the second desulfurization solution contains an NHD solvent. Preferably, the synthesis gas is pressurized to 20 to 100kPa via a first compression device before entering the first desulfurization device. Preferably, the desulfurization process further comprises a second wet desulfurization process, wherein the second wet desulfurization process is that the purified gas flows through a third desulfurization device, enters from the bottom of the third desulfurization device, and is in countercurrent contact with a second desulfurization solution sprayed from the top of the third desulfurization device, so that hydrogen sulfide in the purified gas is removed. Preferably, the synthesis gas enters from the lower part of the desulfurization device and is in countercurrent contact with the desulfurization solution sprayed from the upper part of the desulfurization device to absorb H₂The desulfurized liquid after S becomes a desulfurized rich liquid, flows out from the lower part of the desulfurization device and flows into a jet regeneration device, the jet regeneration device comprises an ejector, an ejector throat and an air suction chamber, the ejector is arranged at the top of the jet regeneration groove, the desulfurized rich liquid is ejected from the ejector, negative pressure is formed in the air suction chamber, a large amount of air enters the ejector air suction chamber from an air inlet and passes through the ejector throat together with the desulfurized rich liquid at high speed, so that the desulfurized rich liquid and the air are subjected to mass transfer reaction, H is₂S is oxidized into elemental sulfur, thereby removing hydrogen sulfide from the synthesis gas. Preferably, the jet regeneration device is provided with an electrode to which a direct current voltage of 10KV or more is applied.

In the purification process of the present invention, preferably, the second desulfurization device is provided with a resistance wire, the resistance wire comprises chromium and nickel, and the crude desulfurization gas flows through the resistance wire, so that H in the crude desulfurization gas₂S, ionizing into elemental sulfur. Preferably, the second desulfurization device is loaded with electrodes, and a direct current voltage higher than 10KV is applied to the electrodes, so that H in the crude desulfurization gas is generated₂S, ionizing into elemental sulfur. Preferably, the crude desulfurization gas is pressurized to 1.0MPa to 3.0MPa through a second compression device before flowing into a second desulfurization device. Further, the second compression device comprises at least two compression apparatuses connected in series. Further, the crude desulfurization gas flows through the second desulfurization device before flowing into the second desulfurization deviceAn adsorption device loaded with an adsorption material comprising activated carbon. Preferably, the purified gas is subjected to a shift process before passing through the third desulfurization unit.

Based on the technical scheme, the desulfurization process provided by the invention prepares the dried low-rank coal into the synthesis gas mainly containing CO and H2 under the condition of no oxygen or micro oxygen, and removes hydrogen sulfide in the synthesis gas to a content of less than 0.1ppm in a dry desulfurization mode, so that the smooth proceeding of a subsequent coal processing process is ensured, and precious volatile components and coal quality in the low-rank coal are fully utilized; the method is simple and feasible to operate, and the existing equipment is mostly used, so that the operation cost is low, and the method is suitable for industrial production.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified. The terms "first," "second," and the like in the present disclosure are used for distinguishing between descriptions and not to imply or imply relative importance.

Preparation example

The invention provides a desulfurization process of synthesis gas, which comprises a first wet desulfurization process and a purification process, wherein the synthesis gas sequentially passes through the first wet desulfurization process and the purification process, the first wet desulfurization process is that the synthesis gas enters from the bottom of a first desulfurization device and is in countercurrent contact with a first desulfurization solution sprayed from the top of the first desulfurization device to remove hydrogen sulfide in the synthesis gas, and then the synthesis gas flows through a first gas-liquid separation device to be separated to obtain crude desulfurization gas; the purification technology does the coarse desulfurization gas flows through second desulphurization unit, second desulphurization unit is including one-level hydroconversion ware and second grade hydroconversion ware, one-level hydroconversion ware loading includes the iron molybdenum catalyst, second grade hydroconversion ware loading includes the nickel molybdenum catalyst, the coarse desulfurization gas flows through behind the one-level hydroconversion ware flow through second grade hydroconversion ware, second desulphurization unit still loading includes the desulfurizer of zinc oxide, will hydrogen sulfide desorption in the coarse desulfurization gas obtains the purified gas.

The raw material low-rank coal can be pulverized coal or lump coal, and when the low-rank coal adopts the lump coal, the pulverized coal with smaller granularity can be obtained by crushing and screening the oversize lump coal. The pulverized coal is preferably used as a raw material, on one hand, the pulverized coal does not need to be crushed and screened, so that the process steps are saved, the heating area is large during drying, the drying efficiency is high, and on the other hand, the pulverized coal is low in price compared with lump coal. Pulverized coal having a particle size of less than 20mm is preferably used, and pulverized coal having a particle size of less than 6mm is still more preferably used.

The low-rank coal generally has 20-55% of volatile components, about 3-15% of tar, 30-60% of fixed carbon, 10-40% of water and the balance of other impurities such as dust. The low-rank coal has low coalification degree but contains abundant oil and gas resources, and the volatile components in the low-rank coal are very beneficial to extracting the synthesis gas, so that the low-rank coal with the volatile components between 30% and 55% is preferred.

The low-rank coal dried by the drying process is conveyed to the gasification reduction process for reaction, and a gasification feeding process can be added before the dried low-rank coal enters the gasification reduction process, so that the dried low-rank coal can rapidly enter a gasification reduction device, the surface area of the material is increased, and the gasification reduction reaction is accelerated.

Wherein, the gasification reduction process is a chemical reaction process for heating the dried low-rank coal under the condition of no oxygen or micro oxygen. The dried low-rank coal is conveyed to a gasification reduction process, and under the heating of heating media such as flue gas and the like, no reaction process is carried outAdding other substances such as additives and the like, generally performing a complex chemical reaction process at the temperature of 350-800 ℃ and under the pressure of less than or equal to 30Kpa to obtain solid carbon and a high-temperature oil-gas mixture, wherein the solid carbon is upgraded coal, the temperature of the upgraded coal is 350-800 ℃, and the volatile matter in the upgraded coal is 8-15 wt%. The high-temperature oil-gas mixture contains CO and H₂、CO₂Hydrocarbon, coal tar, dust, sulfur compounds, and the like.

The sulfur compounds are liable to cause poisoning and deactivation of the reforming conversion catalyst and the methane synthesis catalyst, so that the sulfur compounds in the purified rich gas need to be removed before the reforming conversion process. The purified rich gas enters a coarse desulfurization process for treatment, and H in the purified rich gas is removed₂S removal to 20mg/Nm³The following. The coarse desulfurization process adopts wet coarse desulfurization, the wet flue gas desulfurization technology is a gas-liquid reaction, the reaction speed is high, the desulfurization efficiency is high and generally higher than 90%, the technology is mature, and the application range is wide. The wet desulphurization technology is mature, the production operation is safe and reliable, and the wet desulphurization technology always occupies the dominant position in a plurality of desulphurization technologies, and accounts for more than 80 percent of the total installed capacity of desulphurization. Therefore, the wet desulphurization firstly removes a large amount of H in the rich gas₂And (4) removing the S.

By adopting a wet-process crude desulfurization process, common equipment cannot be operated under certain pressure, so that the air flow which is not compressed and flows is large, and the occupied area of the equipment and the whole set of equipment are large. And the total sulfur content of the gas after the crude desulfurization can not meet the requirements of the subsequent reforming conversion catalyst and the methane synthesis catalyst on the sulfur content. Therefore, the gas treated by the coarse desulfurization process is treated by a first compression process to improve the gas pressure, and then enters a fine desulfurization process, wherein the pressure of the first compression process is 20-25kg, and the temperature is 300-400 ℃. The fine desulfurization process is generally dry desulfurization, can be operated under certain pressure, increases the effective components of sulfur in unit volume of treatment, greatly improves the removal rate of sulfur content, greatly reduces a fine desulfurization device, and improves the utilization rate of equipment.

Therefore, the purification process of the present invention adopts a dry process, thereby combining a wet process and a dry process.

In the wet process of the present invention, preferably, the first desulfurization solution contains a PDS catalyst, and the second desulfurization solution contains an NHD solvent. Preferably, the synthesis gas is pressurized to 20 to 100kPa via a first compression device before entering the first desulfurization device. Preferably, the desulfurization process further comprises a second wet desulfurization process, wherein the second wet desulfurization process is that the purified gas flows through a third desulfurization device, enters from the bottom of the third desulfurization device, and is in countercurrent contact with a second desulfurization solution sprayed from the top of the third desulfurization device, so that hydrogen sulfide in the purified gas is removed. Preferably, the synthesis gas enters from the lower part of the desulfurization device and is in countercurrent contact with the desulfurization solution sprayed from the upper part of the desulfurization device to absorb H₂The desulfurized liquid after S becomes a desulfurized rich liquid, flows out from the lower part of the desulfurization device and flows into a jet regeneration device, the jet regeneration device comprises an ejector, an ejector throat and an air suction chamber, the ejector is arranged at the top of the jet regeneration groove, the desulfurized rich liquid is ejected from the ejector, negative pressure is formed in the air suction chamber, a large amount of air enters the ejector air suction chamber from an air inlet and passes through the ejector throat together with the desulfurized rich liquid at high speed, so that the desulfurized rich liquid and the air are subjected to mass transfer reaction, H is₂S is oxidized into elemental sulfur, thereby removing hydrogen sulfide from the synthesis gas. Preferably, the jet regeneration device is provided with an electrode to which a direct current voltage of 10KV or more is applied.

In the purification process of the invention, preferably, the second desulfurization device is provided with a resistance wire, the resistance wire comprises chromium and nickel, and the crude desulfurization gas flows through the resistance wire, so that H2S in the crude desulfurization gas is ionized into elemental sulfur. Preferably, the second desulfurization device is loaded with electrodes, and a direct current voltage higher than 10KV is applied to the electrodes, so that H2S in the crude desulfurization gas is ionized into elemental sulfur. Preferably, the crude desulfurization gas is pressurized to 1.0MPa to 3.0MPa through a second compression device before flowing into a second desulfurization device. Further, the second compression device comprises at least two compression apparatuses connected in series. Further, the crude desulfurization gas flows through an adsorption device loaded with an adsorption material comprising activated carbon before flowing into the second desulfurization device. Preferably, the purified gas is subjected to a shift process before passing through the third desulfurization unit.

The technical progress of the dry desulfurization process of the present invention was analyzed by analyzing the sulfur content of the obtained desulfurized syngas and the energy consumption per kg of desulfurized syngas through comparative experiments as follows.

Experimental example 1

The desulfurization process of the synthesis gas comprises a first wet desulfurization process and a purification process, wherein the synthesis gas sequentially passes through the first wet desulfurization process and the purification process, the first wet desulfurization process is that the synthesis gas enters from the bottom of a first desulfurization device and is in countercurrent contact with a first desulfurization solution sprayed from the top of the first desulfurization device, hydrogen sulfide in the synthesis gas is removed, and then the synthesis gas flows through a first gas-liquid separation device and is separated to obtain a crude desulfurization gas; the purification technology does the coarse desulfurization gas flows through second desulphurization unit, second desulphurization unit is including one-level hydroconversion ware and second grade hydroconversion ware, one-level hydroconversion ware loading includes the iron molybdenum catalyst, second grade hydroconversion ware loading includes the nickel molybdenum catalyst, the coarse desulfurization gas flows through behind the one-level hydroconversion ware flow through second grade hydroconversion ware, second desulphurization unit still loading includes the desulfurizer of zinc oxide, will hydrogen sulfide desorption in the coarse desulfurization gas obtains the purified gas.

In experimental example 1, a rich gas obtained by using low-rank coal according to quality was used as a raw material gas, and the component of the rich gas included CH₄28-40% of content, 10-15% of CO content and H₂25-40% of CO₂Content 5-10%, C₂H₆Content 2-8%, C₂H₄Content 1-4%, C₃H₆0.5-3% of C₃H₈Content of 0.4-2.5%, C₄H₈0.2-2% of H₂S content 2000-₃The content is 300-800ppm, and the oil condensable matter comprising naphthalene and tar is 2000-6000ppm, and the dust is 2000-6000 ppm.

In the experimental example 1, the synthesis gas sent from the pipeline outside the zone is pressurized to 10-100kPa by a fan, enters the bottom of the first desulfurization device, is in countercurrent contact with the desulfurization solution sprayed from the upper part of the first desulfurization device to remove hydrogen sulfide in the gas, and the gas is sent out of the battery compartment after passing through the gas-liquid separator.

The main reactions taking place in the first desulfurization unit are as follows:

Na₂CO₃+H₂S＝NaHCO₃+NaHS

Na₂CO₃+2HCN＝2NaCN+H₂O+CO₂

absorption of H₂The desulfurized liquid after S becomes a desulfurized rich liquid, flows out from the lower part of the desulfurization device and flows into a jet regeneration device, the jet regeneration device comprises an ejector, an ejector throat and an air suction chamber, the ejector is arranged at the top of the jet regeneration groove, the desulfurized rich liquid is ejected from the ejector, negative pressure is formed in the air suction chamber, a large amount of air enters the ejector air suction chamber from an air inlet and passes through the ejector throat together with the desulfurized rich liquid at high speed, so that the desulfurized rich liquid and the air are subjected to mass transfer reaction, H is₂S is oxidized into elemental sulfur, thereby removing hydrogen sulfide from the synthesis gas. The jet regeneration device is provided with an electrode to which a direct current voltage of 10KV or more is applied.

And then entering a compression working section, wherein the compression working section is used for pressurizing the original synthesis gas so as to meet the technological requirements of the next processing of the synthesis gas. The synthesis gas is pressurized to 1.0-5.0MPa by a reciprocating compressor and is conveyed to a fine desulfurization procedure of a purification working section (a first-stage outlet of raw material gas compression is conveyed to a primary purification procedure for deoiling, decalcification and crude desulfurization treatment, and the treated raw material gas returns to a second-stage inlet of compression); the feed gas compressor is a reciprocating compressor.

The purification process is that the crude desulfurization gas flows through a second desulfurization device, and comprises two parts of the contents of primary purification and fine desulfurization of the synthesis gas, and the second desulfurization device comprises a first-stage hydrogenation converter and a second-stage hydrogenation converter.

(1) The primary purification of the synthesis gas comprises two parts of deoiling and decalcification and crude desulfurization.

The deoiling and the decalcification and the crude desulfurization adopt a physical adsorption process. The oil absorbent is used to absorb the condensable impurities such as naphthalene and tar contained in the synthetic gas, so as to reduce the content of the tar and the naphthalene in the gas.

(2) The fine desulfurization adopts a hydro-conversion medium temperature dry desulfurization process.

The synthetic gas from the compression section is at 10-50 ℃ and 1.0-5.0MPa, and firstly enters two oil filter tanks which can be connected in parallel and in series to remove oil in the synthetic gas, the synthetic gas at the outlet of the oil filter tanks is heated to 200-400 ℃ through a first section temperature regulator, a steam heater, a product heat exchanger and a second section temperature regulator in sequence, and then enters a first pre-hydrogenation converter section temperature regulator and a first-stage hydrogenation converter in sequence, unsaturated hydrocarbon, organic sulfur compounds (COS, thioether, mercaptan and the like), oxygen and the like in the synthetic gas react with hydrogen under the action of an iron-molybdenum catalyst, and the unsaturated hydrocarbon in the synthetic gas is converted into saturated hydrocarbon and the organic sulfur is converted into H which is easy to remove₂S, the temperature is increased to 300-500 ℃, when the temperature exceeds the set value of the bed temperature of the first-stage hydrogenation converter, the cold shock regulating valve is opened to reduce the temperature, and the production is reduced or stopped if necessary.

A typical organic sulfur conversion reaction is:

R-SH+H₂＝RH+H₂S

R-S-R’+2H₂＝R’H+RH+H₂S

COS+H₂＝CO+H₂S

CS₂+4H₂＝2H₂S+CH₄

O₂+2H₂＝2H₂O

the gas from the first-stage hydrogenation converter enters two series-parallel medium-temperature desulfurization tanks after being subjected to heat exchange by a second-stage temperature regulator, and the inorganic sulfur is absorbed at the temperature of about 300-400 ℃.

The synthesis gas from the medium-temperature desulfurization tank still cannot meet the requirement of a liquefaction working section on sulfur content, and needs further hydrogenation and fine desulfurization treatment. The synthesis gas enters a secondary hydrogenation converter for further hydrogenation conversion under the action of a nickel-molybdenum catalyst, and the temperature is 300-400 ℃. The reaction formula is as follows:

C₄H₄S+4H₂＝C₄H₁₀+H₂S

the synthesis gas at the outlet of the second-stage hydrogenation converter passes through two zinc oxide desulfurization tanks connected in series and in parallel to carry out H conversion₂S absorption, the reaction formula is:

Z_nO+H₂S＝ZnS+H₂O(g)

and finally, after heat exchange is carried out on the synthesis gas out of the zinc oxide desulfurization tank through a product heat exchanger and a product cooler, the temperature is 10-50 ℃, the pressure is about 1.0-5.0MPa, and the purified synthesis gas is conveyed to the next working section.

Experimental example 2

Experimental example 2 referring to experimental example 1, except that in the purification process of experimental example 2, the synthesis gas was passed through an iron-molybdenum catalyst, or through a nickel-molybdenum catalyst, and also through a resistance wire, so that H contained in the synthesis gas was supplied with electricity₂S is ionized to elemental sulfur.

Experimental example 3

Experimental example 3 referring to experimental example 1, except that, in the purification process of experimental example 3, the synthesis gas flows through an iron-molybdenum catalyst, or through a nickel-molybdenum catalyst, and also through an electrode, a direct current voltage of more than 10KV is applied to the electrode, so that H contained in the synthesis gas₂S is ionized to elemental sulfur.

Experimental example 4

Experimental example 4 referring to experimental example 1, except that the desulfurization process further includes a second wet desulfurization process of passing the purified gas through a third desulfurization unit, entering from the bottom of the third desulfurization unit, and being in countercurrent contact with a second desulfurization solution sprayed from the top of the third desulfurization unit to remove hydrogen sulfide from the purified gas, the first desulfurization solution contains a PDS catalyst, and the second desulfurization solution contains an NHD solvent.

Comparative example 1

The desulfurization method for preparing natural gas from rich gas by using low-rank coal in a quality-divided manner comprises the following steps:

(1) heating low-rank coal at the temperature of 600 ℃ by isolating air to obtain semi-coke, coal tar and rich gas as byproductsWherein the component of the rich gas comprises CH₄28-40% of content, 10-15% of CO content and H₂25-40% of CO₂Content 5-10%, C₂H₆Content 2-8%, C₂H₄Content 1-4%, C₃H₆0.5-3% of C₃H₈Content of 0.4-2.5%, C₄H₈0.2-2% of H₂S content 2000-₃The content is 300-800 ppm;

(2) through the spraying water washing purification process adopted by the water washing purification unit 2, the pretreated rich gas is further purified, and ammonia gas and sulfide in the rich gas are removed, so that the load of a subsequent desulfurization procedure is reduced, and the pre-desulfurized rich gas is obtained;

(3) all unsaturated hydrocarbons in the coal gas are converted into corresponding saturated hydrocarbons through the hydrogenation unit 3, and organic sulfur is simultaneously converted into H₂S, obtaining hydrogenated rich gas; the hydrogenation unit is used for reacting unsaturated hydrocarbon and organic sulfur compound contained in the synthesis gas with hydrogen under the action of an iron-molybdenum catalyst, wherein the unsaturated hydrocarbon is converted into saturated hydrocarbon, and the organic sulfur is converted into H₂S；

(4) The fine desulfurization unit 4 adopts a dry desulfurization process, solid ZnO is used for desulfurization, and H in the feed gas is removed₂The S content is reduced to<0.1ppm, desulfurized syngas was obtained.

TABLE 1 compositional analysis tables of desulfurized syngas produced in test examples 1-4 and comparative example 1^*1

Composition of	Experimental example 1	Experimental example 2	Experimental example 3	Experimental example 4	Comparative example 1
						Sulfur content	0.06ppm	0.03ppm	0.01ppm	0.01ppm	139.4ppm

TABLE 2 energy consumption analysis tables for desulfurized Synthesis gases of test examples 1 to 4 and comparative example 1

Composition of	Experimental example 1	Experimental example 2	Experimental example 3	Experimental example 4	Comparative example 1
						Energy consumption/kJ	1032	1048	1002	1046	1086

Note: the energy consumption analysis is stopped by that the temperature of the desulfurized synthetic gas is 20-50 ℃ and the pressure is about 1.5-5.0MPa after the desulfurized synthetic gas is subjected to heat exchange through a product heat exchanger and a product cooler, and the purified desulfurized synthetic gas is conveyed to the front of the next working section.

From the results of tables 1 and 2, analyzing the components of the produced desulfurized syngas, we can obtain that, firstly, the hydrogen sulfide content in the desulfurized syngas and the energy consumption can be effectively reduced due to the combination of the wet process and the dry process, the sulfur content is reduced from 139.4ppm of comparative example 1 to 0.06ppm of experimental example 1, and the energy consumption is reduced from 1086kJ of comparative example 1 to 1032kJ of experimental example 1; secondly, in the purification process, the synthesis gas flows through an iron-molybdenum catalyst or a nickel-molybdenum catalyst and also flows through a resistance wire, so that the sulfur content in the pre-desulfurized gas can be obviously reduced from 0.06ppm of experimental example 1 to 0.03ppm of experimental example 2, but the energy consumption is increased to 1048kJ of experimental example 2; thirdly, in the purification process, the electrodes are arranged, so that the sulfur content in the gas after pre-desulfurization can be obviously reduced, namely, 0.06ppm of experimental example 1 is reduced to 0.02ppm of experimental example 3, and the energy consumption is obviously saved due to the fact that the basic energy consumption of the electrodes is low, namely, 1032kJ of the experimental example 1 is reduced to 1002kJ of the experimental example 3; fourthly, the desulfurization process also comprises a second wet desulfurization process, so that the sulfur content in the pre-desulfurized gas can be obviously reduced from 0.06ppm of experimental example 1 to 0.02ppm of experimental example 4, but the energy consumption is increased to 1046kJ of experimental example 4.

In summary, the desulfurization process of the synthesis gas in the invention prepares the dried low-rank coal to mainly contain CO and H under the condition of no oxygen or micro oxygen₂The synthesis gas is desulfurized to the content of less than 0.1ppm by the desulfurization process, so that the subsequent coal processing process is ensured to be smoothly carried out, and precious volatile components and coal quality in the low-rank coal are fully utilized; the system provided by the invention is simple and feasible to operate, is mostly the existing equipment, is low in operation cost, and is suitable for industrial production.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.