阅读说明：本技术 一种焦炉煤气合成氨的方法 (Method for synthesizing ammonia from coke oven gas ) 是由 王永全 项斌 项裕桥 傅凯 陈勇 于 2021-08-26 设计创作，主要内容包括：本发明属于煤化工技术领域,具体涉及焦炉煤气合成氨的方法,包括如下工序：变温吸附工序,通过变温吸附塔吸附净化焦化煤气中包含焦油、萘的杂质,得到预处理气,其中,所述变温吸附塔内自上而下依次设置活性炭层、硅胶层、氧化铝层和焦炭层；变压吸附提氢工序,去除加压后的所述预处理气中的油和水,然后进入变压吸附塔内去除剩余杂质,得到净化H-(2),其中,所述变压吸附塔内自上而下依次设置分子筛层、CO专用吸附剂层、活性炭层、硅胶层和氧化铝层；氨合成工序,将所述变压吸附提氢工序得到的净化H-(2)和外来氮气混合后加压输送至氨合成塔,反应得到氨。本发明方法的工艺流程路线短,运行效益和稳定性高,产品质量好。(The invention belongs to the technical field of coal chemical industry, and particularly relates to a method for synthesizing ammonia from coke oven gas, which comprises the following steps: a temperature swing adsorption step, wherein impurities containing tar and naphthalene in the coking gas are adsorbed and purified by a temperature swing adsorption tower to obtain pre-treatment gas, wherein an active carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer are sequentially arranged in the temperature swing adsorption tower from top to bottom; pressure swing adsorption hydrogen extraction process, namely removing oil and water in the pressurized pretreatment gas, and then feeding the gas into a pressure swing adsorption tower to remove residual impurities to obtain purified H 2 Wherein, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an alumina layer are sequentially arranged in the pressure swing adsorption tower from top to bottom; an ammonia synthesis step of subjecting the purified H obtained in the pressure swing adsorption hydrogen extraction step to 2 Mixing with external nitrogen, pressurizing and conveying to an ammonia synthesis tower, and reacting to obtain ammonia. The method has the advantages of short process flow route, high operation benefit and stability and good product quality.)

1. The method for synthesizing ammonia from coke oven gas is characterized by comprising the following steps of:

a temperature swing adsorption step, wherein impurities containing tar and naphthalene in the coking gas are adsorbed and purified by a temperature swing adsorption tower to obtain pre-treatment gas, wherein an active carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer are sequentially arranged in the temperature swing adsorption tower from top to bottom;

pressure swing adsorption hydrogen extraction process, namely removing oil and water in the pressurized pretreatment gas, and then feeding the gas into a pressure swing adsorption tower to remove residual impurities to obtain purified H₂Wherein, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an alumina layer are sequentially arranged in the pressure swing adsorption tower from top to bottom;

an ammonia synthesis step of subjecting the purified H obtained in the pressure swing adsorption hydrogen extraction step to₂Mixing with external nitrogen, pressurizing and conveying to an ammonia synthesis tower, and reacting to obtain ammonia.

2. The method of claim 1, wherein the temperature swing adsorption column is packed with layers at a packing level, based upon 100% total mass of layers, of: 25.0-35.0% of an activated carbon layer, 35.0-45.0% of a silica gel layer, 5.0-10.0% of an alumina layer and 18.0-25.0% of a coke layer;

preferably, 29.0-31.0% of the activated carbon layer, 40.0-42.0% of the silica gel layer, 5.0-7.0% of the alumina layer and 20.50-22.5% of the coke layer;

more preferably, the filling amount of each layer is 30.10% of the activated carbon layer, 41.95% of the silica gel layer, 6.45% of the alumina layer and 21.50% of the coke layer.

3. The method of claim 1, wherein the pressure swing adsorption column is packed with layers in amounts such that, based on 100% total mass of the layers: 74.0-77.0% of molecular sieve layer, 3.0-5.0% of CO special adsorbent layer, 12.0-15.0% of activated carbon layer, 3.0-5.0% of silica gel layer and 1.5-3.0% of alumina layer;

preferably, the molecular sieve layer is 75.0-76.0%, the CO special adsorbent layer is 3.5-4.5%, the activated carbon layer is 13.5-14.5%, the silica gel layer is 3.5-4.5% and the alumina layer is 1.9-2.5%;

more preferably, the molecular sieve layer is 75.76%, the CO special adsorbent layer is 4.13%, the activated carbon layer is 13.78%, the silica gel layer is 4.13% and the alumina layer is 2.20%.

4. The method according to claim 1, wherein in the temperature swing adsorption tower, the activated carbon has a strip shape and a diameter of 2-5 mm, the silica gel has a spherical shape and a diameter of 2-5 mm, the alumina has a columnar shape and a diameter of 1-3 mm, and the coke has a columnar shape and a diameter of 20-40 mm;

preferably, in the pressure swing adsorption tower, the molecular sieve is spherical and phi 2-3 mm in specification, the CO special adsorbent is spherical and phi 2-3 mm in specification, the activated carbon is strip-shaped and phi 1.5mm in specification, the silica gel is spherical and phi 1-3 mm in specification, and the alumina is spherical and phi 3-5 mm in specification;

preferably, the typical chemical composition of the CO specific adsorbent is CuCl & Na₂O·Al₂O₃·SiO₂。

5. The method according to claim 1, wherein the temperature swing adsorption process employs a plurality of temperature swing adsorption columns, one of which, after adsorption saturation, is subjected to a regeneration process comprising:

a. process for lowering blood pressure

Discharging coke oven gas with first internal pressure to other regenerated temperature swing adsorption towers with second pressure along the adsorption direction of the temperature swing adsorption tower A, wherein the first pressure is higher than the second pressure, and then discharging desorption gas to an out-of-bounds pipe network against the adsorption direction;

b. heating desorption impurity

Heating the desorbed gas by-product of pressure swing adsorption hydrogen extraction process to 140 + -5 deg.C, and purging the adsorption layer in temperature swing adsorption tower A against the adsorption direction to make naphthalene, tar and H₂S and other aromatic compounds are desorbed under the condition of temperature rise, and desorbed gas generated after the regeneration of the temperature swing adsorption tower A is sent back to an outside pipe network;

c. cooling adsorbent

After the desorption of the temperature swing adsorption tower A is finished, stopping heating the regenerated gas, continuing to blow the adsorption layer by using the normal-temperature regenerated gas against the gas inlet direction, cooling the adsorption layer to the adsorption temperature, and returning the desorbed gas after cooling by blowing to an outside pipe network;

d. boosting procedure

And (3) boosting the temperature swing adsorption tower A by using coke oven gas in other temperature swing adsorption towers with the pressure higher than that of the temperature swing adsorption tower A, balancing the internal pressure of the two towers, and then pressurizing the temperature swing adsorption tower A to the adsorption pressure by using the treated coke oven gas against the adsorption direction, so that the temperature swing adsorption tower A completes one round of regeneration and waits for the next adsorption.

6. The method of claim 1, wherein the pressure swing adsorption column employs a purge scheme, and wherein the steps comprising adsorption, pressure equalization and depressurization, forward purge, reverse purge, pressure equalization and pressure boost, and final product gas pressure boost are performed.

7. The method of claim 1, wherein the purified H obtained from the pressure swing adsorption hydrogen extraction process₂And foreign N₂Cooling and separating oil and water after mixing to obtain qualified hydrogen-nitrogen mixed gas, and then pressurizing and feeding the gas into an ammonia synthesis tower.

8. The method of claim 7, wherein the method is operated in a synthetic ammonia system as follows:

the ammonia synthesis system comprises a temperature swing adsorption unit, a pressure swing adsorption hydrogen extraction unit and an ammonia synthesis unit which are connected in sequence;

the temperature swing adsorption unit comprises a plurality of temperature swing adsorption towers which are connected in series, and the temperature swing adsorption towers are sequentially provided with an activated carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer from top to bottom;

the pressure swing adsorption hydrogen extraction unit comprises a plurality of pressure swing adsorption towers which are connected in series, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an aluminum oxide layer are sequentially arranged on the pressure swing adsorption towers from top to bottom, and an inlet of the first pressure swing adsorption tower is connected with a purified gas outlet of the last pressure swing adsorption tower;

the ammonia synthesis unit comprises an ammonia synthesis tower, and the air inlet of the ammonia synthesis tower is connected with the purified H of the last pressure swing adsorption tower₂ An outlet and an outlet of a nitrogen supply;

purification H of the last of said pressure swing adsorption columns₂ The outlet of the hydrogen-nitrogen mixing tank is connected with the inlet of the ammonia synthesis tower through a high-pressure machine, a cooler, a gas-liquid separator, an ammonia separator, a cold exchanger, a circulator and a heat exchanger in front of the synthesis tower in sequence, the outlet of the ammonia synthesis tower is connected with the inlet of a waste heat boiler, the outlet of the waste heat boiler is connected with the inlet of the heat exchanger in front of the synthesis tower, and the outlet of the heat exchanger in front of the synthesis tower is connected with a condenser;

the outlet of the gas-liquid separator is connected with the inlet of the ammonia separator, the outlet of the ammonia separator and the outlet of the condenser are connected with the inlet of the cold exchanger, the gas outlet of the cold exchanger is connected with the inlet of the ammonia cooler, and the outlet of the ammonia cooler is connected with the inlet of the ammonia separator.

9. The method of claim 8, wherein said pressure swing adsorption hydrogen extraction process produces purified H₂Mixing with nitrogen from nitrogen supply device in hydrogen-nitrogen mixing tank, pressurizing in high pressure machine,the pressurized nitrogen-hydrogen mixed gas enters the cooler for cooling, then enters a gas-liquid separator for separating oil and water, then the mixed gas enters an ammonia separator together with the gas from the synthetic ammonia cooler to separate liquid ammonia, the mixed gas after removing the liquid ammonia enters a cold exchanger to recover cold energy and carry out temperature raising on the mixed gas, the mixed gas after temperature raising enters a heat exchanger in front of a synthetic tower after being pressurized by a circulator, and the gas discharged from the waste heat boiler is subjected to heat exchange and temperature rise and then enters an ammonia synthesis tower for reaction, the gas after reaction enters the waste heat boiler for cooling and then enters a heat exchanger in front of the synthesis tower, the synthesis gas after heat exchange and temperature reduction enters a condenser for cooling to 30-50 ℃, then enters a cold exchanger for heat exchange and temperature reduction and is separated to obtain liquid ammonia, the gas discharged from the cold exchanger enters an ammonia cooler for further cooling and condensation of gaseous ammonia, and the gas discharged from the ammonia cooler continues to enter the next cycle.

10. The method of claim 8, wherein the coke oven gas outlet of the coke oven is connected to the inlet of the first one of the temperature swing adsorption columns of the temperature swing adsorption unit via a screw compressor, a primary cooler, and a primary gas-liquid separator in that order, and the purified gas outlet of the last one of the temperature swing adsorption columns of the temperature swing adsorption unit is connected to the inlet of the first one of the pressure swing adsorption columns via a compressor, a secondary cooler, and a secondary gas-liquid separator in that order;

coke oven gas from a coke oven enters a screw compressor to be pressurized, then is cooled through a primary cooler, is separated by a primary gas-liquid separator to remove moisture and liquid impurities in the coke oven gas, enters a temperature swing adsorption unit to adsorb and separate tar and naphthalene carried in the coke oven gas, then enters a secondary cooler to be cooled, and the secondary gas-liquid separator to remove oil drops and water dirt in the coke oven gas, and then enters a pressure swing adsorption unit₂。

Technical Field

The invention relates to the technical field of coal chemical industry, in particular to a method for synthesizing ammonia from coke oven gas.

Background

The coke oven gas is a combustible gas product generated in the thermal decomposition process of low-rank coal at 500-650 ℃ under the condition of air isolation or little air isolation, and generally 300-350m coke oven gas can be produced from each ton of dry coal³The coke oven consumes about half of the coke oven. The coke oven gas is a mixture, the yield and composition of which are different due to the quality of the coal for coking and the different conditions of the coking process, and the main component of which is H₂(55% -70%) and CH₄(15％-30％)、CO(5％-9％)、CO₂(2％-5％)、N₂(2% -6%) and small quantity of other components, and the coke-oven gas can be used for producing hydrogen or preparing ammonia.

The conventional process for synthesizing ammonia by using coke oven gas comprises the following steps:

1. pressurizing coke oven gas from a coking device by a compressor, then entering a fine desulfurization section, converting organic sulfur in the coke oven gas into hydrogen sulfide by hydrogenation, and then removing the hydrogen sulfide by using zinc oxide; the coke oven gas with qualified sulfur content passes through a methane conversion working section to convert methane in the coke oven gas into CO and CO₂、H₂(ii) a Then sequentially carrying out CO conversion and CO conversion₂A removing unit for performing alcohol alkylation (or alcohol alkylation) to remove CO and CO₂Thoroughly removing the ammonia gas, and pressurizing the obtained qualified hydrogen and nitrogen gas by a compressor to produce ammonia.

2. Pressurizing coke oven gas from a coking device by a compressor, then entering a fine desulfurization section, converting organic sulfur in the coke oven gas into hydrogen sulfide by hydrogenation, and then removing the hydrogen sulfide by using zinc oxide; the coke oven gas with qualified sulfur content is extracted by PSA to obtain hydrogen (CO + CO) meeting the requirement of ammonia₂Less than or equal to 10PPm), supplementing qualified nitrogen, and producing ammonia after pressurization by a compressor.

The two production processes need to carry out organic sulfur hydroconversion, the hydroconversion can be carried out at a certain temperature, and the zinc oxide needs to be replaced regularly, so that the coke oven gas needs to be heated and cooled for many times, the investment cost of device construction can be increased, the operation cost is increased, the popularization of the process for synthesizing ammonia by comprehensively utilizing the coke oven gas is restricted, and the improvement of the overall benefit of the coking device is influenced.

Therefore, the utilization mode of the coke oven gas needs to be optimized, the operation benefit of the ammonia synthesis device by the coke oven gas is improved, and a production process with short process flow route and low production cost is developed.

Disclosure of Invention

The invention provides the method for synthesizing ammonia by using the coke oven gas, which has the advantages of short process route and contribution to reducing the production cost, and has better operation benefit, good stability, good product quality of the synthetic ammonia and high purity.

In order to achieve the effect, the invention adopts the following basic concept:

the method for synthesizing ammonia by using coke oven gas comprises the following steps:

a temperature swing adsorption step, wherein impurities containing tar and naphthalene in the coking gas are adsorbed and purified by a temperature swing adsorption tower to obtain pre-treatment gas, wherein an active carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer are sequentially arranged in the temperature swing adsorption tower from top to bottom;

pressure swing adsorption hydrogen extraction process, namely removing oil and water in the pressurized pretreatment gas, and then feeding the gas into a pressure swing adsorption tower to remove residual impurities to obtain purified H₂Wherein, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an alumina layer are sequentially arranged in the pressure swing adsorption tower from top to bottom;

an ammonia synthesis step of subjecting the purified H obtained in the pressure swing adsorption hydrogen extraction step to₂Mixing with external nitrogen, pressurizing and conveying to an ammonia synthesis tower, and reacting to obtain ammonia.

In one embodiment, the temperature swing adsorption column is packed with the following layers, based on 100% of the total mass of each layer: 25.0-35.0% of activated carbon layer, 35.0-45.0% of silica gel layer, 5.0-10.0% of alumina layer and 18.0-25.0% of coke layer.

Preferably, the activated carbon layer is 29.0-31.0%, the silica gel layer is 40.0-42.0%, the alumina layer is 5.0-7.0%, and the coke layer is 20.50-22.5%.

More preferably, the filling amount of each layer is 30.10% of the activated carbon layer, 41.95% of the silica gel layer, 6.45% of the alumina layer and 21.50% of the coke layer.

In one mode, the filling amount of each layer in the pressure swing adsorption tower is as follows based on the total mass of each layer being 100 percent: 74.0-77.0% of molecular sieve layer, 3.0-5.0% of CO special adsorbent layer, 12.0-15.0% of activated carbon layer, 3.0-5.0% of silica gel layer and 1.5-3.0% of alumina layer.

Preferably, the molecular sieve layer is 75.0-76.0%, the CO special adsorbent layer is 3.5-4.5%, the activated carbon layer is 13.5-14.5%, the silica gel layer is 3.5-4.5%, and the alumina layer is 1.9-2.5%.

More preferably, the molecular sieve layer is 75.76%, the CO special adsorbent layer is 4.13%, the activated carbon layer is 13.78%, the silica gel layer is 4.13% and the alumina layer is 2.20%.

As a mode, in the temperature swing adsorption tower, the specification of the activated carbon is strip-shaped and phi 2-5 mm, the specification of the silica gel is spherical and phi 2-5 mm, the specification of the alumina is columnar and phi 1-3 mm, and the specification of the coke is columnar and phi 20-40 mm.

Preferably, in the pressure swing adsorption tower, the molecular sieve is spherical and phi 2-3 mm in specification, the CO special adsorbent is spherical and phi 2-3 mm in specification, the activated carbon is strip-shaped and phi 1.5mm in specification, the silica gel is spherical and phi 1-3 mm in specification, and the alumina is spherical and phi 3-5 mm in specification.

Preferably, the typical chemical composition of the CO specific adsorbent is CuCl & Na₂O·Al₂O₃·SiO₂。

In one aspect, the temperature swing adsorption step employs a plurality of temperature swing adsorption columns, and one of the temperature swing adsorption columns a is saturated by adsorption and then subjected to a regeneration process, the regeneration process including:

a. process for lowering blood pressure

Discharging coke oven gas with first internal pressure to other regenerated temperature swing adsorption towers with second pressure along the adsorption direction of the temperature swing adsorption tower A, wherein the first pressure is higher than the second pressure, and then discharging desorption gas to an out-of-bounds pipe network against the adsorption direction;

b. heating desorption impurity

Heating the desorbed gas by-product of pressure swing adsorption hydrogen extraction process to 140 + -5 deg.C, and purging the adsorption layer in temperature swing adsorption tower A against the adsorption direction to make naphthalene, tar and H₂S and other aromatic compounds are desorbed under the condition of temperature rise, and desorbed gas generated after the regeneration of the temperature swing adsorption tower A is sent back to an outside pipe network;

c. cooling adsorbent

After the desorption of the temperature swing adsorption tower A is finished, stopping heating the regenerated gas, continuing to blow the adsorption layer by using the normal-temperature regenerated gas against the gas inlet direction, cooling the adsorption layer to the adsorption temperature, and returning the desorbed gas after cooling by blowing to an outside pipe network;

d. boosting procedure

And (3) boosting the temperature swing adsorption tower A by using coke oven gas in other temperature swing adsorption towers with the pressure higher than that of the temperature swing adsorption tower A, balancing the internal pressure of the two towers, and then pressurizing the temperature swing adsorption tower A to the adsorption pressure by using the treated coke oven gas against the adsorption direction, so that the temperature swing adsorption tower A completes one round of regeneration and waits for the next adsorption.

As a mode, the pressure swing adsorption tower adopts a flushing process and executes the steps of adsorption, pressure equalizing and reducing, forward discharging, reverse discharging, flushing, pressure equalizing and boosting and final boosting of product gas.

In one embodiment, the purified H obtained in the pressure swing adsorption hydrogen extraction step₂And foreign N₂Cooling and separating oil and water after mixing to obtain qualified hydrogen-nitrogen mixed gas, and then pressurizing and feeding the gas into an ammonia synthesis tower.

By one approach, the process operates in a synthetic ammonia system as follows:

the ammonia synthesis system comprises a temperature swing adsorption unit, a pressure swing adsorption hydrogen extraction unit and an ammonia synthesis unit which are connected in sequence; the temperature swing adsorption unit comprises a plurality of temperature swing adsorption towers which are connected in series, and the temperature swing adsorption towers are sequentially provided with an activated carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer from top to bottom;

the pressure swing adsorption hydrogen extraction unit comprises a plurality of pressure swing adsorption towers which are connected in series, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an aluminum oxide layer are sequentially arranged on the pressure swing adsorption towers from top to bottom, and an inlet of the first pressure swing adsorption tower is connected with a purified gas outlet of the last pressure swing adsorption tower;

the ammonia synthesis unit comprises an ammonia synthesis tower, and the air inlet of the ammonia synthesis tower is connected with the purified H of the last pressure swing adsorption tower₂An outlet and an outlet of a nitrogen supply;

purification H of the last of said pressure swing adsorption columns₂The outlet of the hydrogen-nitrogen mixing tank is connected with the inlet of the ammonia synthesis tower through a high-pressure machine, a cooler, a gas-liquid separator, an ammonia separator, a cold exchanger, a circulator and a heat exchanger in front of the synthesis tower in sequence, the outlet of the ammonia synthesis tower is connected with the inlet of a waste heat boiler, the outlet of the waste heat boiler is connected with the inlet of the heat exchanger in front of the synthesis tower, and the outlet of the heat exchanger in front of the synthesis tower is connected with a condenser;

the outlet of the gas-liquid separator is connected with the inlet of the ammonia separator, the outlet of the ammonia separator and the outlet of the condenser are connected with the inlet of the cold exchanger, the gas outlet of the cold exchanger is connected with the inlet of the ammonia cooler, and the outlet of the ammonia cooler is connected with the inlet of the ammonia separator.

In one embodiment, the purified H obtained in the pressure swing adsorption hydrogen extraction step₂Mixing nitrogen from a nitrogen supply device in a hydrogen-nitrogen mixing tank and pressurizing the mixed gas in a high-pressure machine, introducing the pressurized nitrogen-hydrogen mixed gas into a cooler for cooling, introducing the cooled nitrogen-hydrogen mixed gas into a gas-liquid separator for separating oil and water, introducing the gas and gas from a synthetic ammonia cooler into an ammonia separator for separating liquid ammonia, introducing the mixed gas from which the liquid ammonia is removed into a cold exchanger for recovering cold energy and heating the mixed gas, introducing the heated mixed gas into a heat exchanger in front of a synthetic tower after pressurizing the mixed gas by a circulator, introducing the heated mixed gas into an ammonia synthetic tower for reacting with gas from a waste heat boiler after heat exchange and heating, introducing the reacted gas into a waste heat boiler for cooling, introducing the cooled synthetic gas into a condenser for cooling the synthetic gas to 30-50 ℃, introducing the cooled synthetic gas into the cold exchanger for heat exchange and cooling and separating the liquid ammonia to obtain liquid ammonia, and introducing the cold exchanger out of the cold exchangerThe gas enters an ammonia cooler for further cooling and condensing gaseous ammonia, and the gas coming out of the ammonia cooler continues to enter the next cycle.

As a mode, a coke oven gas outlet of the coke oven is connected to an inlet of a first temperature swing adsorption tower of the temperature swing adsorption unit through a screw compressor, a first-stage cooler and a first-stage gas-liquid separator in sequence, and a purified gas outlet of a last temperature swing adsorption tower of the temperature swing adsorption unit is connected to an inlet of the first pressure swing adsorption tower through the compressor, a second-stage cooler and a second-stage gas-liquid separator in sequence;

coke oven gas from a coke oven enters a screw compressor to be pressurized, then is cooled through a primary cooler, is separated by a primary gas-liquid separator to remove moisture and liquid impurities in the coke oven gas, enters a temperature swing adsorption unit to adsorb and separate tar and naphthalene carried in the coke oven gas, then enters a secondary cooler to be cooled, and the secondary gas-liquid separator to remove oil drops and water dirt in the coke oven gas, and then enters a pressure swing adsorption unit₂。

Compared with the prior art, the technical scheme of the invention has the following advantages:

1. the method for synthesizing ammonia from coke oven gas does not need organic sulfur hydroconversion procedure of conventional process, reduces heating and cooling processes of coke oven gas, shortens process flow route, reduces construction investment of device, reduces operators, reduces operation difficulty, production cost and energy consumption, improves operation stability of device, and improves operation benefit and stability.

2. The invention adopts special filler formula and filling structure to realize the basic removal of hydrogen sulfide and most of organic sulfur in the process of removing impurities such as naphthalene, tar, benzene and the like by temperature swing adsorption (TSA for short), and purifies H by adjusting the filler formula and filling structure in the pressure swing adsorption tower even under the condition of reducing organic sulfur hydroconversion process₂The purity of the product is more than or equal to 99.99 percent (v/v), and the product is CO + CO₂Less than or equal to 10PPm, less than or equal to 0.10PPm of total sulfur content, less than or equal to-40 ℃ of dew point, can fully meet the requirement ofThe requirement of ammonia formation.

3. In order to further avoid the condition that the fluctuation of sulfur content and oxygen content caused by the fluctuation of indexes in the production process affects the long-period stable operation of the device, activated carbon (zinc oxide) is added for desulfurization after the hydrogen and nitrogen are mixed, so that the qualified sulfur content is ensured;

and a deoxidizing tank is further added, and a deoxidizer in the deoxidizing tank is utilized to remove trace oxygen in the hydrogen and the nitrogen until the deoxidizer stably meets the standard of synthetic ammonia requirements.

4. The pressure swing adsorption hydrogen extraction process (PSA hydrogen extraction process for short) adopted by the method can produce hydrogen meeting the ammonia process requirements, and gas purification processes in the conventional ammonia synthesis process, such as CO conversion and CO purification₂Removal, alcohol alkylation (alcohol alkylation), and the like.

5. Under the condition that the whole process flow is basically the same, the packing structures in the temperature swing adsorption tower and the pressure swing adsorption tower can improve H content in the PSA hydrogen extraction process₂The recovery rate of the system is reduced, the consumption is reduced, the operation stability of the system is improved, and the long-period stable operation of the system is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a flow chart illustrating an example of a method for synthesizing ammonia from coke oven gas according to the present invention.

FIG. 2 is a schematic structural diagram of a coke oven gas ammonia synthesis system of the present invention.

The figure is marked with: the system comprises a screw compressor 1, a primary cooler 2, a primary gas-liquid separator 3, a temperature swing adsorption unit 4, a compressor 5, a secondary cooler 6, a secondary gas-liquid separator 7, a pressure swing adsorption hydrogen extraction unit 8, a hydrogen-nitrogen mixing tank 9, a desulfurization and deoxidation tank 10, a high-pressure machine 11, a tertiary cooler 12, a tertiary gas-liquid separator 13, an ammonia separator 14, a circulator 15, a pre-converter heat exchanger 16, an ammonia synthesis tower 17, a waste heat boiler 18, a condenser 19, a cold exchanger 20 and an ammonia cooler 21.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The definitions of "first", "last", "first", "second", "third", etc. in the present invention are only for distinguishing the same devices provided at different positions, and are convenient to describe, and do not unduly limit the technical scheme.

The filler, catalyst and other materials used in the present invention are common commercial products purchased from the market, unless otherwise specified. The reaction temperature and pressure of the synthetic ammonia adopt the existing conventional parameters, which are not the innovation point of the invention and are not described in detail.

The method for synthesizing ammonia by using coke oven gas comprises the following steps:

a temperature swing adsorption step, wherein impurities containing tar and naphthalene in the coking gas are adsorbed and purified by a temperature swing adsorption tower to obtain pre-treatment gas, wherein an active carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer are sequentially arranged in the temperature swing adsorption tower from top to bottom;

pressure swing adsorption hydrogen extraction process, namely removing oil and water in the pressurized pretreatment gas, and then feeding the gas into a pressure swing adsorption tower to remove residual impurities to obtain purified H₂Wherein, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an alumina layer are sequentially arranged in the pressure swing adsorption tower from top to bottom;

an ammonia synthesis step of subjecting the purified H obtained in the pressure swing adsorption hydrogen extraction step to₂Mixing with external nitrogen, pressurizing and conveying to an ammonia synthesis tower, and reacting to obtain ammonia.

FIG. 1 provides a reference flow under the above basic concept, and in order to further improve the purity and yield of the synthetic ammonia, FIG. 1 adds other process steps, such as desulfurization and deoxidation process, so that the synthetic ammonia with satisfactory purity and good yield can be obtained by only adopting the above basic technical scheme of the present invention.

In one embodiment, the temperature swing adsorption column is packed with the following layers, based on 100% of the total mass of each layer: 25.0-35.0% of activated carbon layer, 35.0-45.0% of silica gel layer, 5.0-10.0% of alumina layer and 18.0-25.0% of coke layer.

Preferably, the activated carbon layer is 29.0-31.0%, the silica gel layer is 40.0-42.0%, the alumina layer is 5.0-7.0%, and the coke layer is 20.50-22.5%.

More preferably, the filling amount of each layer is 30.10% of the activated carbon layer, 41.95% of the silica gel layer, 6.45% of the alumina layer and 21.50% of the coke layer.

In one mode, the filling amount of each layer in the pressure swing adsorption tower is as follows based on the total mass of each layer being 100 percent: 74.0-77.0% of molecular sieve layer, 3.0-5.0% of CO special adsorbent layer, 12.0-15.0% of activated carbon layer, 3.0-5.0% of silica gel layer and 1.5-3.0% of alumina layer.

Preferably, the molecular sieve layer is 75.0-76.0%, the CO special adsorbent layer is 3.5-4.5%, the activated carbon layer is 13.5-14.5%, the silica gel layer is 3.5-4.5%, and the alumina layer is 1.9-2.5%.

More preferably, the molecular sieve layer is 75.76%, the CO special adsorbent layer is 4.13%, the activated carbon layer is 13.78%, the silica gel layer is 4.13% and the alumina layer is 2.20%.

The molecular sieve is aluminosilicate with a cubic framework structure, has a large specific surface area and very uniform gap distribution, is used for removing methane and nitrogen, and ensures the purity of a final product.

The typical chemical composition of the special CO adsorbent is CuCl & Na₂O·Al₂O₃·SiO₂Not only has large specific surface area, but also has uniform gap distribution and is used for removing CO.

The activated carbon belongs to water-resistant non-polar activated carbon, has good affinity to almost all organic compounds in raw gas, and is mainly used for removing hydrocarbon components, methane and part of nitrogen.

Silica gel is an amorphous silica with high porosity, inert, non-toxic, non-corrosive in chemical characteristics, used to improve gas flow distribution, remove water, some carbon dioxide, etc.

The alumina is an adsorbent which takes active alumina as a main component and has higher specific surface area and good compressive strength, and is mainly used for improving gas flow distribution and removing moisture.

The excellent H is achieved by arranging the treatment layers of the various substances in the temperature swing adsorption tower and the pressure swing adsorption tower according to the filling structures respectively₂Purification effect, obtaining high-purity H capable of directly carrying out ammonia synthesis₂The desulfurization and deoxidation step is not necessarily separately employed, which contributes to shortening the steps.

In addition, under the condition that the whole process flow is basically the same, the packing structures in the temperature swing adsorption tower and the pressure swing adsorption tower can improve H in the PSA hydrogen extraction process₂The recovery rate of the system is reduced, the consumption is reduced, the operation stability of the system is improved, and the long-period stable operation of the system is ensured.

As a mode, in the temperature swing adsorption tower, the specification of the activated carbon is strip-shaped and phi 2-5 mm, the specification of the silica gel is spherical and phi 2-5 mm, the specification of the alumina is columnar and phi 1-3 mm, and the specification of the coke is columnar and phi 20-40 mm.

In one mode, in the pressure swing adsorption tower, the specification of the molecular sieve is spherical and phi 2-3 mm, the specification of the CO special adsorbent is spherical and phi 2-3 mm, the specification of the activated carbon is strip and phi 1.5mm, the specification of the silica gel is spherical and phi 1-3 mm, and the specification of the alumina is spherical and phi 3-5 mm.

Wherein, the typical chemical composition of the special adsorbent for CO is CuCl & Na₂O·Al₂O₃·SiO₂。

In one aspect, the temperature swing adsorption step employs a plurality of temperature swing adsorption columns, and one of the temperature swing adsorption columns a is saturated by adsorption and then subjected to a regeneration process, the regeneration process including:

a. process for lowering blood pressure

Discharging coke oven gas with first internal pressure to other regenerated temperature swing adsorption towers with second pressure along the adsorption direction of the temperature swing adsorption tower A, wherein the first pressure is higher than the second pressure, and then discharging desorption gas to an out-of-bounds pipe network against the adsorption direction;

b. heating desorption impurity

Heating the desorbed gas by-product of pressure swing adsorption hydrogen extraction process to 140 + -5 deg.C, and purging the adsorption layer in temperature swing adsorption tower A against the adsorption direction to make naphthalene, tar and H₂S and other aromatic compounds are desorbed under the condition of temperature rise, and desorbed gas generated after the regeneration of the temperature swing adsorption tower A is sent back to an outside pipe network;

c. cooling adsorbent

After the desorption of the temperature swing adsorption tower A is finished, stopping heating the regenerated gas, continuing to blow the adsorption layer by using the normal-temperature regenerated gas against the gas inlet direction, cooling the adsorption layer to the adsorption temperature, and returning the desorbed gas after cooling by blowing to an outside pipe network;

d. boosting procedure

And (3) boosting the temperature swing adsorption tower A by using coke oven gas in other temperature swing adsorption towers with the pressure higher than that of the temperature swing adsorption tower A, balancing the internal pressure of the two towers, and then pressurizing the temperature swing adsorption tower A to the adsorption pressure by using the treated coke oven gas against the adsorption direction, so that the temperature swing adsorption tower A completes one round of regeneration and waits for the next adsorption.

The regeneration procedure can fully utilize the gas in the system, reduce the exhaust emission, reduce the operation cost and the energy consumption and is more environment-friendly.

As a mode, the pressure swing adsorption tower adopts a flushing process and executes the steps of adsorption, pressure equalizing and reducing, forward discharging, reverse discharging, flushing, pressure equalizing and boosting and final boosting of product gas.

In one embodiment, the purified H obtained in the pressure swing adsorption hydrogen extraction step₂And foreign N₂Cooling and separating oil and water after mixing to obtain qualified hydrogen-nitrogen mixed gas, and then pressurizing and feeding the gas into an ammonia synthesis tower.

The method for synthesizing ammonia by using coke oven gas can be implemented by combining the following system for synthesizing ammonia by using coke oven gas.

The coke oven gas ammonia synthesis system comprises a temperature swing adsorption unit 4, a pressure swing adsorption hydrogen extraction unit 8 and an ammonia synthesis unit which are connected in sequence;

the temperature swing adsorption unit 4 comprises a plurality of temperature swing adsorption towers connected in series, and the temperature swing adsorption towers are sequentially provided with an activated carbon layer, a silica gel layer, an aluminum oxide layer and a coke layer from top to bottom;

the pressure swing adsorption hydrogen extraction unit 8 comprises a plurality of pressure swing adsorption towers which are connected in series, a molecular sieve layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and an aluminum oxide layer are sequentially arranged on the pressure swing adsorption towers from top to bottom, and an inlet of the first pressure swing adsorption tower is connected with a purified gas outlet of the last pressure swing adsorption tower;

the ammonia synthesis unit comprises an ammonia synthesis tower 17, and the air inlet of the ammonia synthesis tower 17 is connected with the purified H of the last pressure swing adsorption tower₂An outlet and an outlet of the nitrogen supply device. The above definitions of "first", "last", etc. are determined according to the flow order of the air streams in the respective devices.

As shown in fig. 2, which provides a specific configuration of the above system, the coke oven gas outlet of the coking production unit is connected to the inlet of the first temperature swing adsorption column of the temperature swing adsorption unit 4 via a screw compressor 1, a first-stage cooler 2 and a first-stage gas-liquid separator 3 in sequence.

The purified gas outlet of the last temperature swing adsorption tower of the temperature swing adsorption unit 4 is connected to the inlet of the first pressure swing adsorption tower of the pressure swing adsorption hydrogen extraction unit 8 through a compressor 5, a secondary cooler 6 and a secondary gas-liquid separator 7 in sequence.

Preferably, a desulfurization and deoxidation tank 10 is arranged between the outlet of the hydrogen-nitrogen mixing tank 9 and the high-pressure machine 11, namely, the outlet of the hydrogen-nitrogen mixing tank 9 is connected with the inlet of the desulfurization and deoxidation tank 10, and the outlet of the desulfurization and deoxidation tank 10 is connected with the inlet of the high-pressure machine 11.

As a preferred solution (fig. 2 is not shown, and it can be seen that the system is understood by referring to fig. 1), the system is further provided with a desorption gas mixing tank, the gas inlet of the desorption gas mixing tank is connected with the desorption gas outlet of the pressure swing adsorption tower, the gas outlet of the desorption gas mixing tank is connected with the regeneration gas inlet of the temperature swing adsorption tower, and the desorption gas outlet of the temperature swing adsorption tower is connected with a coking production device.

Purification H of the last of said pressure swing adsorption columns₂The outlet of the hydrogen-nitrogen mixing tank 9 is connected with the inlet of the hydrogen-nitrogen mixing tank 9 through the outlet of the nitrogen supply device, the outlet of the hydrogen-nitrogen mixing tank 9 is connected with the inlet of the ammonia synthesis tower 17 through the high-pressure machine 11, the three-stage cooler 12, the three-stage gas-liquid separator 13, the circulator 15 and the heat exchanger 16 in front of the synthesis tower in sequence, the outlet of the ammonia synthesis tower 17 is connected with the inlet of the waste heat boiler 18, the outlet of the waste heat boiler 18 is connected with the inlet of the heat exchanger 16 in front of the synthesis tower, and the outlet of the heat exchanger 16 in front of the synthesis tower is connected with the condenser 19.

An ammonia separator 14 and a cold exchanger 20 both having a liquid ammonia outlet are arranged on the pipeline between the three-stage gas-liquid separator 13 and the circulator 15, the outlet of the three-stage gas-liquid separator 13 is connected with the inlet of the ammonia separator 14, the gas outlet of the ammonia separator 14 and the outlet of the condenser 19 are connected with the inlet of the cold exchanger 20, the gas outlet of the cold exchanger 20 is connected with the inlet of an ammonia cooler 21, and the outlet of the ammonia cooler 21 is connected with the inlet of the ammonia separator 14.

Further, the outlet of the third-stage gas-liquid separator 13 and the outlet of the ammonia cooler 21 are connected together to the inlet of the ammonia separator 14 through a confluence pipe comprising the same pipe section.

The following describes a working process of the system in implementation:

1) coke oven gas purification and PSA hydrogen extraction

Coke oven gas from a coking production device enters a screw compressor 1 for pressurization through pipeline connection, is cooled through a primary cooler 2 after being pressurized to 0.20MPa, is separated from water and liquid impurities through a primary gas-liquid separator 3, enters a temperature swing adsorption unit 4(TSA adsorption unit) for adsorption separation of tar, naphthalene and other impurities carried in the gas, is finally required to have the tar content lower than 2PPm and the naphthalene content lower than 1PPm, is pressurized to 1.60MPa through a compressor 5, is cooled through a secondary cooler 6, enters a secondary gas-liquid separator 7 for removing oil drops and water pollution in the coke oven gas, enters a pressure swing adsorption hydrogen extraction unit 8(PSA adsorption unit), adopts a flushing flow, and comprises the steps of adsorption, pressure equalization, forward release, reverse release, flushing, final pressure boosting and the like in the technical process, and qualified hydrogen is produced.

2) Ammonia synthesis and production of liquid ammonia

Qualified hydrogen from a pressure swing adsorption hydrogen extraction unit 8 and nitrogen from an air separation device enter a hydrogen-nitrogen mixing tank 9, enter a high-pressure machine 11 after passing through a desulfurization and deoxidation tank 10, enter a three-stage cooler 12 for cooling after being pressurized, enter a three-stage gas-liquid separator 13 for separating oil from water, then enter an ammonia separator 14 together with gas from an outlet of an ammonia cooler 21, enter a cold exchanger 20 for separating liquid ammonia, recycle the cold energy of the mixed gas and raise the temperature of the mixed gas, pressurize the gas after being raised in temperature by a circulator 15, enter a heat exchanger 16 in front of a synthesis tower, enter an ammonia synthesis tower 17 after being subjected to heat exchange and temperature raising with gas from a waste heat boiler 18, enter a waste heat boiler 18 for cooling after reaction, enter the heat exchanger 16 in front of the synthesis tower 16, enter a condenser 19 for cooling the synthesis gas after being subjected to heat exchange to about 40 ℃, enter the cold exchanger 20 for further heat exchange and cooling and separating liquid ammonia, the gas enters an ammonia cooler 21 for further cooling, most of the gas ammonia is condensed, and the gas at the outlet of the ammonia cooler 21 enters the next cycle.

The liquid ammonia separated by the ammonia separator 14 and the cold exchanger 20 is sent for sale.

Some embodiments of the method of the present invention are listed below, and the process steps and parameters (e.g., regeneration procedure, temperature, pressure, etc.) not described in detail in the following embodiments are all performed in a unified manner according to the content already described in the above description, and are not repeated in each embodiment.

Example 1

Coke oven gas from a coking production device (coke oven) enters a gas holder for storage and buffering, then enters a pressurizer unit to be pressurized to about 0.2MPa, and is sent to a TSA unit.

1. Temperature swing adsorption (TSA adsorption)

The coke oven gas pressurized to 0.2MPa enters a TSA adsorption unit (comprising at least 1 temperature swing adsorption tower), and is adsorbed and purified by the temperature swing adsorption tower, wherein the temperature swing adsorption tower is filled with 4 layers of adsorbents, 30.10 percent of activated carbon layer, 41.95 percent of silica gel layer, 6.45 percent of alumina layer and 21.50 percent of coke layer are sequentially filled from top to bottom according to the mass percentage, and impurities such as tar, sulfur, naphthalene, benzene and the like are adsorbed to obtain the pretreatment gas.

As an optimized scheme, at least 2 temperature swing adsorption towers are arranged, when a certain temperature swing adsorption tower is saturated in adsorption, the regeneration process is carried out (for the convenience of distinguishing, the temperature swing adsorption tower A is assumed to be ready for regeneration), and the regeneration process comprises the following steps:

a. process for lowering blood pressure

The temperature swing adsorption tower A puts coke oven gas with higher pressure in the tower into other temperature swing adsorption towers with lower pressure and regeneration completed along the adsorption direction, and then releases the pressure along the direction opposite to the adsorption direction, namely towards the inlet end, and the gas is discharged to an outside pipe network.

b. Heating desorption impurity

Heating the desorbed gas by-product of pressure swing adsorption hydrogen extraction process to about 140 deg.C (+ -5 deg.C), and purging the adsorption layer of temperature swing adsorption tower A against the adsorption direction to make naphthalene, tar and H₂S and other aromatic compounds can be completely desorbed under the condition of temperature rise, and the regenerated desorption gas is sent back to an outside pipe network or enters a coke oven.

c. Cooling adsorbent

After desorption, the heating of the regenerated gas is stopped, the adsorption bed layer is continuously blown by the normal-temperature regenerated gas against the gas inlet direction, the adsorption bed layer is cooled to the adsorption temperature (room temperature, less than or equal to 40 ℃), and the cooled desorbed gas is also sent back to an outside pipe network or enters a coke oven.

d. Boosting procedure

And (3) boosting the temperature swing adsorption tower A by using coke oven gas with higher pressure from other temperature swing adsorption towers to ensure that the pressure in the two towers is basically equal, and then boosting the temperature swing adsorption tower A to the adsorption pressure by using the treated coke oven gas against the adsorption direction, so that the temperature swing adsorption tower A can carry out the next adsorption.

2. Pressurization of the preconditioning gas

The pretreated gas treated by the temperature swing adsorption tower enters a compressor to be further pressurized to about 1.6 MPa.

3. Pressure swing adsorption hydrogen extraction (PSA hydrogen extraction)

The coke oven gas pressurized by the coke oven gas compressor is firstly subjected to removal of oil drops, water pollution and the like in the coke oven gas, and then enters a PSA hydrogen extraction unit consisting of a plurality of pressure swing adsorption towers for PSA hydrogen extraction.

The PSA hydrogen extraction unit consists of a plurality of pressure swing adsorption towers, and 75.76% of molecular sieve layer, 4.13% of CO special adsorbent layer, 13.78% of activated carbon layer, 4.13% of silica gel layer and 2.20% of alumina layer are sequentially arranged in the pressure swing adsorption towers from top to bottom according to mass percentage.

One or two pressure swing adsorption towers are always in a feeding adsorption state, and pressure equalization is carried out for multiple times.

The pressure swing adsorption tower adopts a flushing flow, and the steps of adsorption, pressure equalizing and reducing, forward discharging, reverse discharging, flushing, pressure equalizing and boosting and final boosting of product gas are executed.

Removing most impurities except hydrogen at one time under the condition of selective adsorption of each layer of adsorbent to obtain purified hydrogen (CO + CO) with qualified purity₂Less than or equal to 10 PPm; the total sulfur content is less than or equal to 0.10PPm), is discharged from the top of the tower, is sent to a desulfurization and deoxidation unit outside after being subjected to pressure stabilization and buffering by a hydrogen buffer tank.

When the front edge of the mass transfer area (called adsorption front edge) of the adsorbed impurities reaches a certain position of the reserved section of the bed layer outlet, the adsorption is stopped, and the regeneration process is switched to.

4. Desulfurization and deoxidation and pressurization of a hydrogen-nitrogen mixture

The process is taken as an optimization process, and if the process needs to be shortened, the process can be omitted according to actual needs.

Purified hydrogen from the PSA hydrogen extraction unit is mixed with externally qualified nitrogen, then enters a two-stage dry desulfurization tank, and a desulfurizer (such as one or two of high-efficiency active carbon or zinc oxide) in the desulfurization tank is used for removing trace total sulfur in the hydrogen-nitrogen mixed gas.

Then the mixed gas is sent into a deoxidizing tank, oxygen in the mixed gas of hydrogen and nitrogen is removed by utilizing a palladium catalyst in the deoxidizing tank at the temperature of 100 ℃, and the qualified mixed gas of hydrogen and nitrogen is sent to a compressor of the mixed gas of hydrogen and nitrogen for pressurization.

5. Synthetic ammonia process

And (3) sending the qualified hydrogen-nitrogen mixed gas from the desulfurization and deoxidation unit to a compressor unit for further pressurization, compressing the gas to about 15.0MPa, sending the gas to an ammonia synthesis unit for reaction, and synthesizing ammonia.

The packing pattern of the packing layer of the temperature swing adsorption column is specifically shown in table 1 below.

TABLE 1

The packing pattern of the packing layer of the pressure swing adsorption column is specifically shown in table 2 below.

TABLE 2

The purity of the liquid ammonia synthesized by the method is 99.9 wt%.

Example 2

The only difference from example 1 is that the desulfurization and deoxidation step was omitted, and the purified hydrogen obtained in the PSA hydrogen extraction step was mixed with acceptable nitrogen gas from outside, pressurized, and sent to an ammonia synthesis column for reaction, and the other steps were the same as those in example 1.

The purity of the liquid ammonia synthesized by the method is 99.8 wt%.

Example 3

The difference from example 1 is only that the packing amount of each layer in the temperature swing adsorption column is different, specifically as follows: 25% of activated carbon layer, 45% of silica gel layer, 10% of alumina layer and 20% of coke layer, the others being in accordance with example 1.

The purity of the liquid ammonia synthesized by the method is 99.3 wt%.

Example 4

The difference from example 1 is only that the packing amount of each layer in the temperature swing adsorption column is different, specifically as follows: 35% of activated carbon layer, 35% of silica gel layer, 5% of alumina layer and 25% of coke layer, the others being identical to those of example 1.

The purity of the liquid ammonia synthesized by the method is 99.4 wt%.

Example 5

The difference from example 1 is only that the filling amount of each layer in the pressure swing adsorption tower is different, and the following is specific: 74% of molecular sieve layer, 5% of adsorbent layer special for CO, 15% of activated carbon layer, 3% of silica gel layer and 3% of alumina layer, the rest is the same as that of example 1.

The purity of the liquid ammonia synthesized by the method is 99.0 wt%.

Example 6

The difference from example 1 is only that the filling amount of each layer in the pressure swing adsorption tower is different, and the following is specific: 77% of molecular sieve layer, 3% of adsorbent layer special for CO, 12% of activated carbon layer, 5% of silica gel layer and 3% of alumina layer, the others being the same as those in example 1.

The purity of the liquid ammonia synthesized by the method is 99.2 wt%.

Comparative example 1

The difference from the embodiment 1 is only that the structure of the packing layer in the temperature swing adsorption tower is different, and the specific difference is as follows:

the temperature swing adsorption tower is internally and sequentially provided with a coke layer, a silica gel layer, an alumina layer and an activated carbon layer from top to bottom, and the rest parts are consistent with those in the embodiment 1.

The purity of the liquid ammonia synthesized by the method is 97.4 wt%.

H in PSA hydrogen extraction process₂The recovery of (D) was reduced by 15% as compared with example 1.

Comparative example 2

The difference from the embodiment 1 is only that the structure of the packing layer in the pressure swing adsorption tower is different, and the specific difference is as follows:

an alumina layer, a CO special adsorbent layer, an activated carbon layer, a silica gel layer and a molecular sieve layer are sequentially arranged in the pressure swing adsorption tower from top to bottom, and the rest parts are consistent with those in the embodiment 1.

The purity of the liquid ammonia synthesized by the method is 96.1 wt%.

H in PSA hydrogen extraction process₂The recovery of (D) was reduced by 17% as compared with example 1.

Comparative example 3

The difference from example 1 is only that there is no pressure swing adsorption hydrogen extraction process, and the others are the same as example 1. The purity of the liquid ammonia synthesized by the method is 80.3 wt%.

Comparative example 4

The only difference from example 1 is that there is no temperature swing adsorption process, and the others are the same as example 1. The purity of the liquid ammonia synthesized by the method is 72.1 wt%.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.