阅读说明：本技术 一种从生物质燃气中制备满足车用氢标准的氢气的方法 (Method for preparing hydrogen meeting vehicle hydrogen standard from biomass gas ) 是由 盛卫东 季伟 宋欣 于 2019-09-30 设计创作，主要内容包括：本发明提供了一种从生物质燃气中制备满足车用氢标准的氢气的方法,所述方法是以固定床生物质气化炉产生的燃气为原料,压缩处理、脱油脱萘处理、CO变换处理、粗脱硫处理、脱氨处理、变压吸附处理、精脱硫处理和脱水处理,制得满足车用氢标准的CO含量小于0.2μmol/mol,总硫含量小于0.004μmol/mol的氢气,氢气产量为1000万方/年。本发明具有工艺技术先进可靠、生物质燃气利用与能量利用率高、装置自控程度高、生产过程清洁等优点,符合国家的产业政策、能源政策和环保政策。(The invention provides a method for preparing hydrogen meeting the vehicle hydrogen standard from biomass gas, which takes gas generated by a fixed bed biomass gasification furnace as a raw material, and comprises the steps of compression treatment, deoiling and decalcification treatment, CO transformation treatment, crude desulfurization treatment, deamination treatment, pressure swing adsorption treatment, fine desulfurization treatment and dehydration treatment to prepare the hydrogen meeting the vehicle hydrogen standard, wherein the content of CO is less than 0.2 mu mol/mol, the total sulfur content is less than 0.004 mu mol/mol, and the yield of the hydrogen is 1000 ten thousand square/year. The invention has the advantages of advanced and reliable process technology, high utilization rate of biomass gas and energy, high degree of automatic control of the device, clean production process and the like, and conforms to the national industrial policy, energy policy and environmental protection policy.)

1. A method of producing hydrogen gas from biomass fuel gas that meets vehicular hydrogen standards, the method comprising the steps of:

the biomass fuel gas is sequentially subjected to compression treatment, deoiling and decalcification treatment, CO transformation treatment, crude desulfurization treatment, deamination treatment, pressure swing adsorption treatment, fine desulfurization treatment and dehydration treatment to prepare hydrogen with the CO content of less than 0.2 mu mol/mol and the total sulfur content of less than 0.004 mu mol/mol.

2. The method of claim 1, wherein the biomass fuel gas comprises the following substances in percentage by volume:

components H₂ CO CO₂ N₂ CH₄ CnHm O₂ Content (wt.) 12～16 35～39 15～16 14～17 13～16 1.2～1.4 0.5～1.0

Wherein CnHm represents an organic substance such as a hydrocarbon, for example, naphthalene or tar;

the naphthalene content in the biomass fuel gas is more than or equal to 100mg/Nm³(ii) a The content of tar and dust is more than or equal to 10mg/Nm³(ii) a H in the biomass gas₂S content is more than or equal to 200mg/Nm³。

3. A method according to claim 1 or 2, wherein the compression treatment is such as pressurizing the biomass fuel gas to 1.0-1.5MPa, such as 1.2 MPa;

the compression process is achieved by means of a compressor selected from a twin compressor or a screw compressor.

4. The method according to any one of claims 1 to 3, wherein the biomass fuel gas after compression is subjected to a deoiling and decalcification treatment, which is carried out in a deoiling tower and a decalcification tower;

the compressed biomass fuel gas enters from the bottom of the deoiling tower, the biomass fuel gas passes through the deoiling agent bed layer from bottom to top, most of tar components contained in the biomass fuel gas are adsorbed by the deoiling agent, and the rest components are separated from the deoiling tower and enter the naphthalene removing tower;

the biomass fuel gas without tar enters from the bottom of the naphthalene removing tower, the biomass fuel gas passes through the bed layer of the naphthalene removing agent from bottom to top, naphthalene contained in the biomass fuel gas is absorbed by the naphthalene removing agent, and the rest components are separated from the naphthalene removing tower;

tar in biomass gas subjected to deoiling and decalcification treatment is deoiled to be less than or equal to 1mg/Nm³Naphthalene is removed to less than or equal to 5mg/Nm³；

The method also comprises the step of carrying out regeneration treatment on the adsorbed deoiling tower and the adsorbed naphthalene removing tower;

the regeneration treatment can be heating, blowing and regenerating the deoiling tower and the naphthalene removal tower by the desorption gas after the heated pressure swing adsorption treatment; after regeneration is finished, the unheated desorption gas after pressure swing adsorption treatment is used for purging the deoiling tower and the naphthalene removal tower and is cooled; after cooling, the deoiling tower and the naphthalene removing tower have the capacity of treating biomass gas.

5. The method according to any one of claims 1-4, wherein the CO shift process comprises the steps of: allowing the biomass gas and the water vapor to pass through the catalyst bed layer simultaneously, and reacting CO in the biomass gas with the water vapor to generate carbon dioxide and hydrogen;

the catalyst can be, for example, a sulfur tolerant wide temperature shift catalyst of the Fe-Mo, Co-Mo series;

the CO conversion treatment comprises the following steps:

(1) carrying out heat exchange on the biomass gas to the temperature of 200-230 ℃;

(2) after adding the water vapor, the temperature is continuously raised to 350-450 ℃ (such as 400 ℃), and the CO content in the gas phase component is reduced to about 20-30%, such as 28%;

(3) performing water-cooling shock treatment to reduce the temperature of the gas-phase components to 200-250 ℃; subsequently, the temperature is continuously increased to 250 ℃ and 350 ℃ (such as 300 ℃), and the CO content in the gas phase component is reduced to about 8-15%, such as 11%;

(4) performing water-cooling treatment again to reduce the temperature of the gas-phase component to 180-220 ℃; subsequently, the temperature is continuously raised to 230 ℃ and 250 ℃ (such as 240 ℃), and the CO content in the gas phase component is reduced to about 2-5%, such as 3.5%;

(5) the temperature is then reduced to 180 ℃ and 210 ℃ at which time the CO content of the gas phase component is reduced to about 1-3%, e.g., 1.5%.

6. A method according to any one of claims 1-5, wherein the crude desulfurization treatment is performed in a crude desulfurization tower, such as at least two crude desulfurization towers; the biomass fuel gas enters the coarse desulfurization tower from the bottom of the coarse desulfurization tower, wherein most of sulfur-containing substances stay in a desulfurizer, and the desulfurized biomass fuel gas is collected from the top of the coarse desulfurization tower and then sent to a deamination tower for deamination treatment;

h in biomass gas after coarse desulfurization treatment₂The content of S is less than or equal to 20mg/Nm³；

The method also comprises the step of carrying out regeneration treatment on the adsorbed coarse desulfurization tower;

the regeneration treatment can be heating, purging and regenerating the crude desulfurization tower by using the desorption gas subjected to the heated pressure swing adsorption treatment; after the regeneration is finished, the unheated desorption gas after the pressure swing adsorption treatment is used for purging and cooling the crude desulfurization tower; after cooling, the crude desulfurization tower has the capability of treating the biomass fuel gas.

7. The method of any one of claims 1-6, wherein the deamination is performed in a deamination tower, such as at least three deamination towers, wherein the deamination tower is filled with a deamination adsorbent, and the ammonia content of the deaminated biomass fuel gas is less than 1 ppm;

the adsorbent is selected from silica gel, molecular sieve and other adsorbents;

the method also comprises the step of carrying out regeneration treatment on the deamination tower after adsorption;

the regeneration treatment can be heating, purging and regenerating the deamination tower by using desorption gas subjected to the heated pressure swing adsorption treatment; and after the regeneration is finished, the unheated desorption gas after the pressure swing adsorption treatment is used for purging and cooling the deamination tower, and after the cooling is finished, the deamination tower has the capacity of treating the biomass gas.

8. The method according to any one of claims 1 to 7, wherein the pressure swing adsorption treatment is performed in an adsorption tower, the biomass fuel gas enters the adsorption tower from the bottom of the adsorption tower, components such as carbon dioxide, nitrogen, methane and carbon monoxide in the biomass fuel gas are retained on the surface of an adsorbent, and hydrogen and the like are collected from the top of the adsorption tower as non-adsorbed components;

the CO content of the biomass gas is less than 0.2 mu mol/mol after the biomass gas is subjected to pressure swing adsorption treatment;

the gas phase component obtained from the top of the adsorption tower is used for fine desulfurization treatment, and the gas containing components such as carbon dioxide, nitrogen, methane, carbon monoxide and the like separated from the adsorption tower is used as adsorption gas for regeneration gas of other process steps for heating or cooling.

9. The method according to any one of claims 1 to 8, wherein the fine desulfurization treatment is to feed the biomass fuel gas subjected to pressure swing adsorption to a fine desulfurization process, and the fine desulfurization treatment comprises an organic sulfur conversion step and H₂S removing;

the organic sulfur conversion step comprises pre-hydroconversion, primary hydroconversion and secondary hydroconversion; carrying out pre-hydrogenation conversion, primary hydrogenation conversion and secondary hydrogenation conversion on the biomass fuel gas in sequence according to the material flow direction;

the pre-hydrogenation conversion is generally arranged into a plurality of pre-hydrogenation conversion units, and redundant pre-hydrogenation conversion units are reserved;

the pre-hydrogenation conversion and the first-stage hydrogenation conversion both use iron-molybdenum catalysts;

the catalyst for the second-stage hydroconversion is a cobalt and molybdenum conversion catalyst or a nickel-cobalt-molybdenum catalyst;

said H₂The S removing step comprises the steps of enabling the biomass gas to pass through a preheater and a heater to reach the reaction temperature and then enter a fine desulfurization tower, wherein H in the biomass gas₂S reacts with a fine desulfurizing agent to remove a system; the fine desulfurizing agent is selected from zinc oxide;the total sulfur content in the biomass fuel gas after fine desulfurization is less than 0.004 mu mol/mol.

10. The method according to any one of claims 1 to 9, wherein the dehydration treatment employs an isobaric drying process, the dehydration treatment being carried out in a drying tower; the number of the drying towers can be 1, 2, preferably 2; wherein 1 drying tower is in a working state, the other 1 drying tower is in a regeneration state, and a drying agent is filled in the drying tower;

the moisture content in the dried biomass fuel gas is less than or equal to 3 ppm; the adsorption working time of each drying tower is about 8 hours; the regeneration process of the drying tower comprises two steps of heating regeneration and blowing cooling; in the heating regeneration process, the temperature of the regeneration gas is raised to 260 ℃ by a heater and then enters a dehydration tower to be regenerated, so that the temperature of the adsorbent is raised, the moisture in the adsorbent is desorbed, and the water is separated after cooling and liquid separation; in the cold blowing process, the regeneration gas is directly sent to the drying tower in the regeneration state, the temperature of the drying tower is reduced to the normal temperature, and the drying tower is waited for reuse.

Technical Field

The invention belongs to the technical field of biomass gas preparation, and particularly relates to a method for preparing hydrogen meeting vehicle hydrogen standards from biomass gas.

Background

China is a big agricultural country, the problem of excess straws is serious, and the straws are no longer needed to be used as main fuel in many areas. In order to rob for harvest, redundant straws are often directly burnt, and the straws generate a large amount of smoke in the field burning process, thereby bringing serious influence on the atmospheric environment.

The utilization mode of the straw mainly comprises the following steps: straw combustion power generation, straw solidification, straw production of fuel ethanol, composite board production, straw papermaking, comprehensive utilization and the like, wherein at present, primary utilization is still used for straw utilization, and combustion power generation is a main utilization mode.

The biomass fuel gas is gas generated by biomass gasification, and mainly contains hydrogen, methane, carbon monoxide, carbon dioxide, nitrogen, benzene, sulfur, ammonia, tar, naphthalene and other impurities. At present, the biomass fuel gas is mainly used as fuel for power generation, and the value of hydrogen in the biomass fuel gas is not fully utilized.

In recent years, with the breakthrough of hydrogen fuel cell technology, the rapid development of new energy automobiles and the increasing importance of the nation on clean energy, hydrogen fuel cells have unique superiority in the aspects of comprehensive energy efficiency, environmental friendliness, high reliability and the like, and are considered as the first choice of clean and efficient power generation technology in the 21 st century. The hydrogen fuel cell has wide market prospect, and the production and application of the hydrogen matched with the hydrogen fuel cell for the vehicle have good economic and social benefits. At present, the domestic hydrogen fuel cell market is active, and in China, the reliability of the hydrogen fuel cell product is proved through commercial operation verification. The normalized multi-line operation of the hydrogen fuel cell public transport is realized by the Buddha, Shanghai, Zhangkou and Zhengzhou; the Buddha mountain newly invests 70 buses at the end of 2018, and plans to newly invest 70 buses in the early 2019; opening family in 2018, and starting commercial demonstration operation. Meanwhile, relevant plans are also made by various governments such as Shanghai, Jiangsu, Guangdong, Shandong, Hubei and the like. This also indicates that the added value is higher when hydrogen is used for the hydrogen fuel cell.

However, hydrogen gas suitable for hydrogen fuel cells is required to have not only high purity of more than 99.99% but also a specific impurity content. However, the hydrogen gas which meets the requirements of the hydrogen fuel cell cannot be obtained by the existing process steps.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for preparing hydrogen meeting the vehicle hydrogen standard from biomass gas, the method takes the biomass gas generated by a fixed bed biomass gasification furnace as a raw material, and the hydrogen meeting the vehicle hydrogen standard is prepared by compression treatment, deoiling and decalcification treatment, CO transformation treatment, crude desulfurization treatment, deamination treatment, pressure swing adsorption treatment, fine desulfurization treatment and dehydration treatment, and the hydrogen with the CO content of less than 0.2 mu mol/mol and the total sulfur content of less than 0.004 mu mol/mol is obtained, and the hydrogen yield can reach 1000 ten thousand square per year. The invention has the advantages of advanced and reliable process technology, high utilization rate of biomass gas and energy, high degree of automatic control of the device, clean production process and the like, and conforms to the national industrial policy, energy policy and environmental protection policy.

The purpose of the invention is realized by the following technical scheme:

a method of producing hydrogen gas from biomass fuel gas that meets vehicular hydrogen standards, the method comprising the steps of:

the biomass fuel gas is sequentially subjected to compression treatment, deoiling and decalcification treatment, CO transformation treatment, crude desulfurization treatment, deamination treatment, pressure swing adsorption treatment, fine desulfurization treatment and dehydration treatment to prepare hydrogen with the CO content of less than 0.2 mu mol/mol and the total sulfur content of less than 0.004 mu mol/mol.

According to the invention, the hydrogen gas is a hydrogen gas that meets the automotive hydrogen standard.

According to the invention, the biomass fuel gas can be obtained by a conventional method in the field, such as biomass fuel gas obtained by fermenting rice straws, wheat straws, rape straws and the like.

Preferably, the biomass fuel gas is prepared by a biomass gasification method, and the biomass gasification process is not a single chemical reaction and is essentially a complex reaction network formed by a series of sequential and parallel reactions and the interaction between intermediate products thereof. The chemical reaction involved is as follows: the method comprises the following steps of pyrolysis/devolatilization reaction of fuel, gasification reaction of semicoke, cracking/reforming reaction of tar and low-carbon hydrocarbon, combustion reaction of carbon residue and the like, wherein the specific chemical reactions are as follows:

pyrolysis/devolatilization reaction:

Fuel→Char+Tar(C_mH_n)+Gases(CO+CO₂+CH₄+H₂,etc.) (4.1)

semi-coke gasification reaction:

C+0.5O₂→CO (4.4)

tar and methane cracking/reforming reactions:

Tar→Gases(CO+CO₂+CH₄+H₂,etc.)+Coke (4.5)

CH₄→2H₂+Coke (4.8)

and (3) carbon residue combustion reaction:

C+O₂→CO₂ (4.11)

water-gas shift reaction:

methanation reaction:

CO₂+4H₂→2H₂O+CH₄ (4.14)

wherein, air, oxygen, water vapor and the like or the mixture thereof can be used as gasification media, but different gasification media have different influences on the gas production composition and the gasification effect.

According to the invention, the biomass fuel gas contains the following substances in percentage by volume:

components

H2

CO

CO2

N2

CH4

CnHm

O2

Content (wt.)

12～16

35～39

15～16

14～17

13～16

1.2～1.4

0.5～1.0

Wherein CnHm represents an organic substance such as a hydrocarbon, for example, naphthalene, tar, or the like.

According to the invention, the naphthalene content in the biomass fuel gas is more than or equal to 100mg/Nm³(ii) a The content of tar and dust is more than or equal to 10mg/Nm³(ii) a H in the biomass gas₂S content is more than or equal to 200mg/Nm³。

According to the invention, the compression treatment is for example a pressurization of the biomass fuel gas to 1.0-1.5MPa, for example 1.2 MPa; the biomass fuel gas mainly contains a large amount of organic matter components, so that complete deoiling and naphthalene removing treatment can be guaranteed through compression treatment, and tar and naphthalene components in the biomass fuel gas are completely removed.

According to the invention, the compression process is carried out by means of a compressor selected from a twin compressor or a screw compressor.

The main machine cooling form of the screw compressor adopts softened water or diesel oil spraying, and the influence of impurities on a cylinder body can be prevented.

Wherein, because the biomass fuel gas contains tar, dust and the like, the biomass fuel gas is fatal to an impeller of a centrifugal compressor and is difficult to ensure the continuous normal operation of the compressor; the reciprocating compressor has better performance than a centrifugal compressor, and although biomass gas contains impurities such as tar, dust and the like, the compressor can be ensured to continuously and stably operate in a certain period by periodic purging maintenance in operation.

According to the invention, the compressed biomass fuel gas is subjected to deoiling and decalcification treatment, and the deoiling and decalcification treatment is carried out in a deoiling tower and a decalcification tower.

Illustratively, the compressed biomass fuel gas enters from the bottom of the deoiling tower, the biomass fuel gas passes through a deoiling agent (deoiling agent conventional in the field, such as porous material, such as activated carbon, expanded graphite and the like) bed layer from bottom to top, most of tar components contained in the biomass fuel gas are adsorbed by the deoiling agent, and the rest components are separated from the deoiling tower and enter the naphthalene removing tower.

The biomass fuel gas after tar removal enters from the bottom of the naphthalene removal tower, the biomass fuel gas passes through a bed layer of a naphthalene removal agent (a naphthalene removal agent in the field, such as bentonite and the like) from bottom to top, naphthalene contained in the biomass fuel gas is absorbed by the naphthalene removal agent, and the rest components are separated from the naphthalene removal tower.

According to the invention, tar in the biomass gas subjected to deoiling and decalcification treatment is deoiled to be less than or equal to 1mg/Nm³Naphthalene is removed to less than or equal to 5mg/Nm³。

According to the invention, the method also comprises the steps of carrying out regeneration treatment on the adsorbed deoiling tower and the adsorbed naphthalene removing tower;

the regeneration treatment can be heating, blowing and regenerating the deoiling tower and the naphthalene removal tower by the desorption gas after the heated pressure swing adsorption treatment; after regeneration is finished, the unheated desorption gas after pressure swing adsorption treatment is used for purging the deoiling tower and the naphthalene removal tower and is cooled; after cooling, the deoiling tower and the naphthalene removing tower have the capacity of treating biomass gas.

According to the invention, the specific components of the biomass fuel gas have low hydrogen concentration and high carbon monoxide content, so that the content of hydrogen in the biomass fuel gas can be increased by adopting CO conversion treatment.

According to the invention, the CO shift process comprises the following steps: and (2) simultaneously passing the biomass gas and the water vapor through the catalyst bed layer, and reacting CO in the biomass gas with the water vapor to generate carbon dioxide and hydrogen.

The catalyst may be, for example, a sulfur-tolerant wide-temperature shift catalyst of Fe-Mo or Co-Mo series.

Wherein the shift reaction of carbon monoxide and water vapor is a equimolecular, reversible exothermic reaction.

CO+H₂O＝CO₂+H₂，ΔH＝-41.16KJ/mol。

According to the invention, the CO shift process comprises the following steps:

(1) carrying out heat exchange on the biomass gas to the temperature of 200-230 ℃;

(2) after adding the water vapor, the temperature is continuously raised to 350-450 ℃ (such as 400 ℃), and the CO content in the gas phase component is reduced to about 20-30%, such as 28%;

(3) performing water-cooling shock treatment to reduce the temperature of the gas-phase components to 200-250 ℃; subsequently, the temperature is continuously increased to 250 ℃ and 350 ℃ (such as 300 ℃), and the CO content in the gas phase component is reduced to about 8-15%, such as 11%;

(4) performing water-cooling treatment again to reduce the temperature of the gas-phase component to 180-220 ℃; subsequently, the temperature is continuously raised to 230 ℃ and 250 ℃ (such as 240 ℃), and the CO content in the gas phase component is reduced to about 2-5%, such as 3.5%;

(5) the temperature is then reduced to 180 ℃ and 210 ℃ at which time the CO content of the gas phase component is reduced to about 1-3%, e.g., 1.5%.

According to the invention, after CO transformation treatment, most of CO in the biomass fuel gas is transformed into hydrogen. The remaining CO can be further removed by the following steps.

According to the invention, the crude desulfurization treatment is carried out in a crude desulfurization tower, for example in at least two crude desulfurization towers; the biomass fuel gas enters the coarse desulfurization tower from the bottom of the coarse desulfurization tower, wherein most of sulfur-containing substances (such as H)₂S) stays in a desulfurizing agent (known in the field), and the desulfurized biomass fuel gas is collected from the top of a coarse desulfurizing tower and then sent to a deamination tower for deamination treatment.

According to the invention, H in the biomass fuel gas after the coarse desulfurization treatment₂The content of S is less than or equal to 20mg/Nm³。

According to the invention, the method also comprises the step of carrying out regeneration treatment on the adsorbed coarse desulfurization tower;

the regeneration treatment can be heating, purging and regenerating the crude desulfurization tower by using the desorption gas subjected to the heated pressure swing adsorption treatment; after the regeneration is finished, the unheated desorption gas after the pressure swing adsorption treatment is used for purging and cooling the crude desulfurization tower; after cooling, the crude desulfurization tower has the capability of treating the biomass fuel gas.

According to the invention, the deamination is carried out in a deamination tower, for example in at least three deamination towers, into which the biomass fuel gas is fed in the operating state. And a deamination adsorbent is filled in the deamination tower, and the ammonia content in the deaminated biomass fuel gas is less than 1 ppm.

For example, the adsorbent is selected from silica gel, molecular sieves, and the like.

According to the invention, the method also comprises the step of carrying out regeneration treatment on the adsorbed deamination tower;

the regeneration treatment can be heating, purging and regenerating the deamination tower by using desorption gas subjected to the heated pressure swing adsorption treatment; and after the regeneration is finished, the unheated desorption gas after the pressure swing adsorption treatment is used for purging and cooling the deamination tower, and after the cooling is finished, the deamination tower has the capacity of treating the biomass gas.

The biomass fuel gas contains ammonia impurities, the deamination is usually carried out by adopting a method of washing at a lower temperature, but a large amount of ammonia-containing wastewater is generated after washing, the wastewater is difficult to treat, and even if the wastewater is treated, the obtained circulating water can cause ammonia in the gas to be accumulated and difficult to remove.

According to the invention, the purpose of the pressure swing adsorption treatment is to further increase the content of hydrogen in the biomass fuel gas, and the pressure swing adsorption is based on physical adsorption of gas molecules on the inner surface of an adsorbent (porous solid substance), and the adsorbent is used for easily adsorbing high-boiling-point components and not easily adsorbing low-boiling-point components under the same pressure; the adsorbent can realize the separation of mixed gas with multiple components mixed together by the characteristics of increasing the adsorption capacity of the same component under high pressure (adsorption component) and reducing the adsorption capacity under low pressure (desorption component).

According to the invention, the pressure swing adsorption treatment is completed in the adsorption tower, the biomass fuel gas enters the adsorption tower from the bottom of the adsorption tower, components such as carbon dioxide, nitrogen, methane and carbon monoxide in the biomass fuel gas are stopped on the surface of the adsorbent, and hydrogen and the like are collected from the top of the adsorption tower as non-adsorption components.

According to the invention, the CO content of the biomass fuel gas after pressure swing adsorption treatment is less than 0.2 mu mol/mol.

The gas phase component obtained from the top of the adsorption tower is used for fine desulfurization treatment, and the gas containing components such as carbon dioxide, nitrogen, methane, carbon monoxide and the like separated from the adsorption tower is used as adsorption gas for regeneration gas of other process steps for heating or cooling.

Through the pressure swing adsorption treatment, the separation of each component in the biomass gas can be further realized, and the purification treatment of the hydrogen is realized.

According to the present invention, the pressure swing adsorption is treated by methods known in the art, for example, see the method disclosed in chinese patent application No. 201610186416.

According to the invention, the fine desulfurization treatment is to introduce the biomass fuel gas subjected to pressure swing adsorption into a fine desulfurization process, and the fine desulfurization treatment comprises an organic sulfur conversion step and H₂And S removing.

Wherein the step of organic sulfur conversion comprises pre-hydroconversion, primary hydroconversion and secondary hydroconversion; carrying out pre-hydrogenation conversion, primary hydrogenation conversion and secondary hydrogenation conversion on the biomass fuel gas in sequence according to the material flow direction; the pre-hydrogenation conversion step is arranged for avoiding the adverse effect of partial impurities in the biomass fuel gas on the organic sulfur conversion catalyst, so that the pre-hydrogenation conversion is arranged before the first-stage hydrogenation conversion to protect the first-stage hydrogenation conversion catalyst.

The pre-hydrogenation conversion is generally arranged into a plurality of pre-hydrogenation conversion units, and redundant pre-hydrogenation conversion units are reserved to ensure long-period and stable operation.

The pre-hydrogenation conversion and the first-stage hydrogenation conversion both use iron-molybdenum catalysts.

The first-stage hydroconversion can hydrogenate most of sulfur-containing substances in the biomass fuel gas and convert the substances into hydrogen sulfide.

The purpose of the secondary hydroconversion configuration is to convert all unconverted organic sulfur in the biomass fuel gas to inorganic sulfur (H)₂S), the second-stage hydrogenation conversion catalyst is generally cobalt or molybdenum conversion catalyst or nickel-cobalt-molybdenum catalyst, and has the characteristics of high conversion rate and high purification degree on organic sulfur.

In the invention, different conversion catalysts are selected according to different characteristics of primary and secondary organic sulfur conversion, primary hydro-conversion requires that most organic sulfur is converted under higher concentration, and the requirement on purification degree is not high, so that an iron-molybdenum catalyst with low price can be selected; the second-stage hydrogenation conversion requires that organic sulfur is basically removed completely, a cobalt and molybdenum conversion catalyst or a nickel-cobalt-molybdenum catalyst with high price is required to be selected, and in order to obtain high price-performance ratio, the first-stage hydrogenation load is increased and the second-stage hydrogenation load is reduced as much as possible.

Wherein, the H₂The S removing step comprises the steps of enabling the biomass gas to pass through a preheater and a heater to reach the reaction temperature and then enter a fine desulfurization tower, wherein H in the biomass gas₂S reacts with the fine desulfurizing agent to remove the system. The fine desulfurizing agent is selected from zinc oxide; the total sulfur content in the biomass fuel gas after fine desulfurization is less than 0.004 mu mol/mol.

In the application, the coarse desulfurization treatment and the fine desulfurization treatment are matched, so that on one hand, the high-efficiency removal of sulfur-containing substances in the biomass fuel gas is realized, and the total sulfur content in the prepared hydrogen is ensured to be less than 0.004 mu mol/mol; meanwhile, better economic benefit is obtained, and no risk of environmental pollution exists.

In the invention, the sulfur-containing substances with higher content are subjected to coarse desulfurization treatment, namely, H is desulfurized by adopting a wet desulfurization process₂S is converted to elemental sulfur, which can be used asAnd the method is a byproduct sale, and the risk of environmental pollution does not exist. The increase of the consumption of the desulfurizer and the equipment investment caused by directly adopting dry desulfurization are avoided, and meanwhile, the replaced desulfurizer has potential risks in the aspect of environmental protection.

According to the invention, the dehydration treatment adopts an isobaric drying process, and the dehydration treatment is carried out in a drying tower; the number of the drying towers can be 1, 2, preferably 2.

For example, 1 of the drying towers is in operation, and the other 1 is in regeneration, and the drying towers are filled with drying agent.

The moisture content in the dried biomass fuel gas is less than or equal to 3 ppm. The adsorption working time of each drying tower is about 8 hours. The regeneration process of the drying tower comprises two steps of heating regeneration and blowing cooling. In the heating regeneration process, the regeneration gas is heated to 260 ℃ by a heater and then enters a dehydration tower to be regenerated, so that the adsorbent is heated, the moisture in the adsorbent is desorbed, and the water is separated after cooling and liquid separation. In the cold blowing process, the regeneration gas is directly sent to the drying tower in the regeneration state, the temperature of the drying tower is reduced to the normal temperature, and the drying tower is waited for reuse.

The invention has the beneficial effects that:

the invention provides a method for preparing hydrogen meeting the vehicle hydrogen standard from biomass gas, which takes gas generated by a fixed bed biomass gasification furnace as a raw material, and comprises the steps of compression treatment, deoiling and decalcification treatment, CO transformation treatment, crude desulfurization treatment, deamination treatment, pressure swing adsorption treatment, fine desulfurization treatment and dehydration treatment to prepare the hydrogen meeting the vehicle hydrogen standard, wherein the content of CO is less than 0.2 mu mol/mol, the total sulfur content is less than 0.004 mu mol/mol, and the yield of the hydrogen is 1000 ten thousand square/year. The invention has the advantages of advanced and reliable process technology, high utilization rate of biomass gas and energy, high degree of automatic control of the device, clean production process and the like, and conforms to the national industrial policy, energy policy and environmental protection policy.

Drawings

FIG. 1 is a process flow diagram of the method of the present invention.

Detailed Description

The preparation method of the present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.