CN110550606A - device and method for preparing high-purity hydrogen from hydrogen-containing gas under unsteady state - Google Patents
device and method for preparing high-purity hydrogen from hydrogen-containing gas under unsteady state Download PDFInfo
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- CN110550606A CN110550606A CN201810565973.8A CN201810565973A CN110550606A CN 110550606 A CN110550606 A CN 110550606A CN 201810565973 A CN201810565973 A CN 201810565973A CN 110550606 A CN110550606 A CN 110550606A
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
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- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/508—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by selective and reversible uptake by an appropriate medium, i.e. the uptake being based on physical or chemical sorption phenomena or on reversible chemical reactions
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Abstract
The invention relates to the field of high-purity hydrogen preparation, in particular to a device and a method for preparing high-purity hydrogen from hydrogen-containing gas under an unsteady state. The device comprises: a hydrogen-containing gas supply unit (9), a pressure swing adsorption unit (1), a hydrogen absorption unit (2), a hydrogen storage unit (3) and a regeneration gas return line (4). The method comprises the following steps: (1) adsorbing heavy component gas in the hydrogen-containing gas under adsorption pressure to obtain hydrogen-containing intermediate product gas; (2) contacting the intermediate product gas with the hydrogen storage alloy to absorb hydrogen therein; (3) resolving the absorbed hydrogen under resolving conditions to obtain product gas; (4) desorbing the adsorbed heavy component gas to obtain regenerated gas; the hydrogen-containing gas contains a regeneration gas. The product gas obtained by the method has high purity, and the purity is 99.999 percent; the process flow is simple, the operation is convenient, complex pretreatment is not needed, and various complex gas sources can be treated; the hydrogen recovery rate is high; the heavy component gas can be recovered as a by-product gas.
Description
Technical Field
The invention relates to the field of high-purity hydrogen preparation, in particular to a device and a method for preparing high-purity hydrogen from hydrogen-containing gas under an unsteady state.
Background
Hydrogen is an important chemical raw material, industrial protective gas and clean fuel, for example, hydrogen is one of the main raw materials in the synthetic ammonia industry, and hydrogen is widely used for the desulfurization of naphtha, gas oil, fuel oil and heavy oil and the hydrofining of unsaturated hydrocarbon and the like in the oil refining industry to improve the quality of oil products; in the electronics and metallurgical industry, hydrogen is mainly used as a reducing gas; in fuel cell automobile houses, hydrogen is an important fuel. With the increasingly strict environmental regulations and the good combustion performance of hydrogen, the market in the future has a huge potential demand for hydrogen. The purity of hydrogen is highly desirable in industrial processes, such as the electronics industry where purity levels of greater than 99.999% are required, and in some cases even higher. Therefore, the hydrogen-containing raw gas needs to be separated and purified to meet different production requirements. Currently developed hydrogen separation methods include pressure swing adsorption, cryogenic methods, membrane separation, and metal hydride methods.
21. The basic principle of Pressure Swing Adsorption (PSA) separation technology is to utilize the Adsorption characteristic difference of different gas components on a solid material and the characteristic that the Adsorption quantity changes with the Pressure, and realize the separation or purification of gas by periodically changing the Pressure of an Adsorption bed layer.
22. A cryogenic separation method, called cryogenic rectification method, features that the different relative volatilities of raw materials are used to make the raw materials pass through gas turbine expansion for refrigeration, the components in dry gas are condensed at low temp. according to the technological requirements, and the various hydrocarbons are separated one by one according to their boiling points by rectification method.
3. Membrane separation method: the membrane separation is a new high-efficiency separation technology, which uses a membrane as a selective barrier layer, a certain amount of energy difference exists on two sides of the membrane as power, certain components are allowed to permeate and other components in a mixture are retained, and the mobility of each component permeating the membrane is different, so that the separation purpose is achieved. The process flow of the membrane separation is very simple, the operation is convenient, and the investment is low; however, the film-forming technique (such as uniformity, stability, aging resistance, heat resistance, etc. of the film) is required to be continuously improved, the service life of the film is short, and the feed gas is required to be free of solids and oil droplets to prevent damage to the film module. The purity of the product is not high (99%), but the pressure of the required raw material gas is high, and the purity of the product hydrogen can reach 99% by adopting a two-stage membrane separator.
4. Metal hydride method: the metal hydride purifying method is to utilize the hydrogen storage material to absorb hydrogen at low temperature and release hydrogen at high temperature to realize the purification of hydrogen, the purity of the product hydrogen is very high, but the requirement of the hydrogen purity in the raw material gas is more than 99.99%, and the hydrogen storage metal material can generate brittle fracture and pulverization phenomena after being recycled for many times, and the production scale is not large, so the method is not suitable for the large-scale separation and purification of crude hydrogen and hydrogen-containing tail gas.
therefore, it is important to develop a method that can achieve both recovery rate and hydrogen purity.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a device and a method for preparing high-purity hydrogen from hydrogen-containing gas under an unsteady state, wherein the yield of the hydrogen is high, the concentration of the product hydrogen is more than 99.999 percent, and the recovery rate of the hydrogen can be up to more than 75 percent.
In order to achieve the above object, an aspect of the present invention provides an apparatus for producing high-purity hydrogen gas from a hydrogen-containing gas under an unsteady state, the apparatus comprising:
A hydrogen-containing gas supply unit;
the pressure swing adsorption unit is used for carrying out pressure swing adsorption on heavy component gas relative to the hydrogen in the hydrogen-containing gas from the hydrogen-containing gas supply unit to obtain hydrogen-containing intermediate product gas;
The hydrogen absorption unit is used for absorbing hydrogen in the hydrogen-containing intermediate product gas;
the hydrogen storage unit is used for receiving the analyzed hydrogen from the hydrogen absorption unit;
And a regeneration gas return line for sending the regeneration gas obtained by regenerating the pressure swing adsorption unit to the hydrogen-containing gas supply unit, and mixing the regeneration gas with the gas contained in the hydrogen-containing gas supply unit to obtain the hydrogen-containing gas.
In a second aspect, the present invention provides a method for producing high purity hydrogen gas from a hydrogen-containing gas under an unsteady state, the method comprising:
(1) Adsorbing heavy component gas relative to hydrogen in the hydrogen-containing gas in a pressure swing adsorption unit under the adsorption pressure of the heavy component gas relative to the hydrogen to obtain hydrogen-containing intermediate product gas;
(2) contacting the hydrogen-containing intermediate product gas with a hydrogen storage alloy in a hydrogen absorption unit to absorb hydrogen in the hydrogen-containing intermediate product gas;
(3) Under the analysis condition, analyzing the hydrogen absorbed in the step to obtain product gas;
(4) Desorbing the heavy component gas which is adsorbed in the pressure swing adsorption unit and is relative to the hydrogen to regenerate the pressure swing adsorption unit to obtain regenerated gas;
Wherein the hydrogen-containing gas contains the regeneration gas.
The device and the method provided by the invention have the following advantages: (1) the purity of the product gas is high, the hydrogen with the purity of 99.999 percent can be obtained, and the recovery rate of the hydrogen can reach more than 75 percent; (2) the process flow is simple, the operation is convenient, complex pretreatment is not needed, and various complex gas sources can be treated; (3) the hydrogen recovery rate is high; (4) the heavy component gas can be recycled as a byproduct gas.
Drawings
fig. 1 shows an apparatus for producing high purity hydrogen gas from a hydrogen-containing gas in an unsteady state according to an embodiment of the present invention.
Fig. 2 fig. 1 shows an apparatus for producing high purity hydrogen gas from a hydrogen-containing gas in an unsteady state according to another embodiment of the present invention.
Description of the reference numerals
1 pressure swing adsorption unit 2 hydrogen absorption unit 3 hydrogen storage unit
4 regeneration gas return line 5 first gas recovery unit 6 second gas recovery unit
7 gas buffer tank 8 vacuumizing unit 9 hydrogen-containing gas supply unit
V1-V14 valve
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
According to a first aspect of the present invention, there is provided an apparatus for producing high purity hydrogen gas from a hydrogen-containing gas under an unsteady state, the apparatus comprising:
A hydrogen-containing gas supply unit 9;
the pressure swing adsorption unit 1 is used for carrying out pressure swing adsorption on heavy component gas relative to hydrogen in the hydrogen-containing gas from the hydrogen-containing gas supply unit 9 to obtain hydrogen-containing intermediate product gas;
the hydrogen absorption unit 2 is used for absorbing hydrogen in the hydrogen-containing intermediate product gas;
A hydrogen storage unit 3 for receiving the desorbed hydrogen from the hydrogen absorption unit 2;
And a regeneration gas return line 4 for sending the regeneration gas obtained by regenerating the pressure swing adsorption unit 1 to the hydrogen-containing gas supply unit 9, and mixing the regeneration gas with the gas contained therein as the hydrogen-containing gas.
In the present invention, the term "non-stable" means: firstly, the adsorption and absorption processes are unstable processes; secondly, the adsorption time is different in different cycle periods, so the operation time sequence is unstable. The operation time sequence is unstable because the regeneration gas is recovered by 100% in the process flow as the raw material gas after the adsorption process is finished, so the composition of the raw material gas changes constantly along with the increase of the concentration of the regeneration gas, and the operation time sequence changes along with the change of the raw material gas because the composition of the raw material gas changes, and the separation process is always in the unstable operation process.
In the present invention, the hydrogen-containing gas (raw material gas) may be any hydrogen-containing gas, and is generally a hydrogen-containing raw material gas generally used for producing high-purity hydrogen. For example, the hydrogen-containing gas (raw gas) can be various industrial exhaust tail gases containing hydrogen with the concentration of 20-85 vol%, such as methanol purge gas, coke oven gas tail gas, chlor-alkali industry hydrogen-containing tail gas, and the like.
In the present invention, the pressure swing adsorption unit 1 may be composed of one or more pressure swing adsorption towers filled with a filler (adsorbent) capable of specifically adsorbing a heavy component gas relative to hydrogen in a hydrogen-containing gas. The type of the filler may be specifically selected depending on the composition of the raw material gas, and may be one or more, and may be selected from, for example, activated carbon, molecular sieves, silica gel, carbon molecular sieves, activated alumina, zeolite, and various modified adsorbents. For example, when the raw material gas is a mixed gas of hydrogen and carbon dioxide, the filler may be activated carbon; when the raw material gas is a mixed gas of hydrogen and nitrogen or argon, the filler can be activated carbon and/or 5A molecular sieve. The invention is not further illustrated here.
The adsorption pressure of the heavy component may be specifically adjusted according to the composition of the raw material gas, and preferably, the adsorption pressure is 0.15 to 5 MPa. For example, when the feed gas is methanol purge gas tail gas, the adsorption pressure may be 1.0-3.0 MPa; when the raw material gas is coke oven gas tail gas, the adsorption pressure can be 0.15-1.0 MPa. The invention is not further illustrated here.
in the present invention, the method for providing the adsorption pressure in the pressure swing adsorption unit 1 is not particularly limited, and for example, the adsorption pressure may be provided by feeding a product gas in a reverse direction to the pressure swing adsorption unit 1, or the adsorption pressure may be provided by feeding a hydrogen-containing gas (feed gas) to the pressure swing adsorption unit 1. The present invention preferably provides the adsorption pressure by passing product gas in reverse direction into the pressure swing adsorption unit 1. The adsorption pressure may be provided by a pressure difference between the feed pressure of the feed gas and the discharge pressure of the intermediate product when the overall process is operating.
the hydrogen-containing gas of the present invention contains the regeneration gas, and the content of the heavy component in the raw material gas is continuously increased along with the increase of the concentration of the regeneration gas in the raw material gas, so the composition of the raw material gas in each cycle of adsorption is continuously changed, and the adsorption time needs to be specifically changed according to the composition of the raw material gas, and a person skilled in the art can specifically adjust the adsorption time according to actual conditions.
Preferably, the number of the pressure swing adsorption towers of the invention is more than 2, and in the preferred case, the continuous separation of the hydrogen-containing gas can be realized, that is, through reasonable time sequence arrangement, when 1 pressure swing adsorption tower is regenerated, the other pressure swing adsorption towers can be in a working state, so that the continuous separation of the hydrogen-containing gas can be realized, and the separation time is greatly shortened.
In the present invention, preferably, the apparatus of the present invention further comprises a gas buffer tank 7 disposed between the pressure swing adsorption unit 1 and the hydrogen absorption unit 2, for temporarily storing the hydrogen-containing intermediate product gas. The gas buffer tank 7 can temporarily store excessive intermediate product gas on the one hand, so that resource waste is avoided, and on the other hand, the intermediate product gas can be supplied to the hydrogen absorption unit 2 by stable gas flow, so that hydrogen is absorbed more sufficiently.
In the present invention, the hydrogen absorption unit 2 may be composed of one or more hydrogen absorption towers filled with a hydrogen storage alloy that can react with hydrogen containing gas to form metal hydride. The hydrogen storage alloy can be various conventional hydrogen storage alloys for reacting with hydrogen, and at least one of rare earth hydrogen storage alloy, AB type titanium-based hydrogen storage alloy, vanadium-based solid solution type hydrogen storage alloy, magnesium-based hydrogen storage alloy and AB2 type Laves phase titanium-based hydrogen storage alloy is preferably selected in the invention.
the conditions for the reaction of hydrogen with the hydrogen storage alloy may be selected conventionally, and preferably, in order to achieve the absorption reaction of hydrogen with maximum efficiency and to remove other impurity gases, the hydrogen absorption is carried out at a plateau pressure (0.5 to 5MPa) or more at a specific working temperature (e.g., 0 to 250 ℃) for hydrogen storage of the selected hydrogen storage alloy. The specific operating temperature and plateau pressure for each hydrogen storage alloy are well known to those skilled in the art and will not be described in detail herein.
Preferably, the number of the hydrogen absorption towers of the present invention is more than 2, and in this preferred case, the continuous separation of the hydrogen-containing gas can be realized, that is, through reasonable timing arrangement, when 1 of the hydrogen absorption towers analyzes the hydrogen, the other hydrogen absorption towers can be in a working state, so that the continuous separation of the hydrogen-containing gas can be realized, and the separation time is greatly shortened.
In the present invention, the analysis of the hydrogen in the hydrogen absorption unit 2 may include room temperature (5-40 ℃) reduced pressure analysis, elevated temperature and reduced pressure analysis, and vacuum analysis, and the analysis of the hydrogen may be performed under the plateau pressure at the specific working temperature of the selected hydrogen storage alloy.
in the present invention, it is preferable that before the analysis of the hydrogen gas in the hydrogen absorption unit 2, the method further includes removing the unadsorbed gas remaining in the hydrogen absorption unit 2, and for example, the unadsorbed impurity gas may be discharged through the byproduct gas line by the gas buffer tank 7.
In the present invention, during each cycle, a portion of the intermediate product gas remains in the bulk phase of the pressure swing adsorption unit 1 and may provide at least a portion of the adsorption pressure for the pressure swing adsorption unit 1. Therefore, preferably, the apparatus of the present invention further comprises a first gas recovery unit 5 for pressure equalization and depressurization or pressure equalization of the pressure swing adsorption unit 1. Specifically, after the adsorption of the pressure swing adsorption unit 1 is completed and before the pressure swing adsorption unit 1 is regenerated, a part of intermediate product gas remaining in the pressure swing adsorption unit 1 may be equalized to the first gas recovery unit 5 (i.e., the pressure equalization of the pressure swing adsorption unit 1 is completed), and after the pressure swing adsorption unit 1 is regenerated, the intermediate product gas in the first gas recovery unit 5 is equalized to the pressure swing adsorption unit 1 so as to provide at least a part of adsorption pressure for the pressure swing adsorption unit 1 (i.e., the pressure equalization of the pressure swing adsorption unit 1 is completed).
preferably, after the pressure equalization, the intermediate product gas in the first gas recovery unit 5 may be sent to the hydrogen absorption unit 2 and/or the intermediate gas buffer tank 7, and may be returned to the feed gas to be mixed therewith for recycling again, and the latter is preferred in the present invention.
In the present invention, preferably, the apparatus provided by the present invention further comprises a second gas recovery unit 6, configured to recover the regeneration gas obtained after the pressure swing adsorption unit 1 is regenerated, so as to return to the raw material gas at a stable flow rate, which does not cause a disturbance of the raw material gas supply flow, thereby ensuring smooth operation of the apparatus, and ensuring the recovery rate of hydrogen and the purity of the final product.
In the present invention, the method for regenerating the pressure swing adsorption unit 1 is not particularly limited as long as the purpose of regeneration can be achieved. According to a preferred embodiment of the invention, the product gas is used for its regeneration. In this preferred case, the pressure swing adsorption unit 1 may be connected to a hydrogen storage unit 3, the hydrogen storage unit 3 supplying a purge gas to the pressure swing adsorption unit 1 to complete the regeneration of the pressure swing adsorption unit 1, and the purged gas is preferably introduced into the second gas recovery unit 6 as a regeneration gas. According to another preferred embodiment of the present invention, a vacuum-pumping unit 8 may be provided between the pressure swing adsorption unit 1 and the second gas recovery unit 6 to pump out the heavy component gas in the pressure swing adsorption unit 1, thereby obtaining a regeneration gas and introducing it into the second gas recovery unit 6. The evacuation unit 8 may be a vacuum pump, and the evacuation conditions are not particularly limited as long as the heavy component gas can be efficiently evacuated to complete the regeneration of the pressure swing adsorption unit 1.
In the present invention, after the present invention completes one adsorption, absorption, desorption of the hydrogen-containing gas and the regeneration of the pressure swing adsorption unit 1 and returns the regenerated regeneration gas to the raw material gas, it is counted that 1 cycle is completed. After several cycles, when the content of heavy components in the regeneration gas of the present invention reaches a certain concentration, for example, above 85 vol%, the regeneration gas is treated as a waste gas through a waste gas pipeline, and the regeneration gas is not recovered, but discharged as a byproduct gas for other uses.
in the present invention, the flow of gas between the units can be controlled by valves arranged in the lines, which is illustrated in fig. 1, which illustrates a specific embodiment of the present invention,
(1) Valves V8 and V14 are provided between the pressure swing adsorption unit 1 and the hydrogen storage unit 3, and before adsorption begins, valves V8 and V14 may be opened to allow a portion of the product gas to flow into the pressure swing adsorption unit 1 and reach the adsorption pressure, thereby completing the back gas.
(2) Closing the valve V14, opening the valves V1, V2 and V5 arranged between the feeding unit and the pressure swing adsorption unit 1 and the valve V12 arranged between the pressure swing adsorption unit 1 and the gas buffer tank 7, leading the raw material gas to enter the pressure swing adsorption unit 1, leading the light component gas such as hydrogen to enter the gas buffer tank through the pressure swing adsorption unit 1, leading the heavy component gas molecules to be adsorbed to the concentration of the adsorbent for trapping, and finishing the adsorption process after the concentration front edge of the heavy component reaches a certain position of the adsorbent bed.
(3) the valve V11 provided between the gas buffer tank 7 and the hydrogen absorption unit 2 is opened to communicate them, hydrogen reacts with the hydrogen storage alloy in the hydrogen absorption unit 2 to form metal hydride, and when the metal absorption reaches saturation, the valve V11 is closed.
(4) The valve V12 is opened to discharge the unabsorbed impurity gas remaining in the gas buffer tank 7 through the by-product gas line. At the same time, the valve V13 provided between the hydrogen absorption unit 2 and the hydrogen storage unit 3 is opened to allow hydrogen gas to be desorbed from the hydrogen storage alloy, thereby obtaining a high-purity hydrogen product.
(5) Valves V5 and V6 provided between the pressure swing adsorption unit 1 and the first gas recovery unit 5 are opened to communicate with each other, and the intermediate product gas of the adsorbent phase in the pressure swing adsorption unit 1 flows into the first gas recovery unit 5. When the pressures of the two pressure vessels are equal, the pressure equalization is finished.
(6) the product gas flows into the pressure swing adsorption unit 1 for purge regeneration by opening valves V8 and V14 and valves V5 and V7 disposed between the pressure swing adsorption unit 1 and the second gas recovery unit 6: the regeneration gas is stored in the second gas recovery unit 6.
alternatively, the valves V5 and V7 provided between the pressure swing adsorption unit 1 and the second gas recovery unit 6 are opened, the vacuum unit 8 is opened, and the gas in the pressure swing adsorption unit 1 is pumped to the second gas recovery unit 6, thereby realizing the regeneration of the pressure swing adsorption unit 1.
(7) The valves V5 and V6 provided between the pressure swing adsorption unit 1 and the first gas recovery unit 5 are opened to communicate with each other, and the intermediate product gas in the first gas recovery unit 5 flows into the pressure swing adsorption unit 1. When the pressures of the two pressure vessels are equal, the pressure equalization is finished.
(8) The valves V6 and V3 provided between the first gas recovery unit 5 and the feed unit and the valves V7 and V4 provided between the second gas recovery unit 6 and the feed unit were opened to re-compress the recovered gas and mix it with the feed gas, and the mixture was again subjected to adsorption separation as the feed gas.
Or the valves V9 and V12 provided between the first gas recovery unit 5 and the gas buffer tank 7 are opened to let the intermediate product gas in the first gas recovery unit 5 enter the gas buffer tank 7.
(9) After several cycles, the heavy component gas concentration in the raw material gas reaches a certain proportion, the valve V10 is opened, and the product gas after the heavy component concentration is output as the byproduct gas.
In the present application, it should be noted that, in each step as described above, except for the opened valve, the other valves are all in the closed state.
According to a second aspect of the present invention, there is provided a method for producing high purity hydrogen gas from a hydrogen-containing gas under an unsteady state, the method comprising:
(1) Adsorbing heavy component gas relative to hydrogen in the hydrogen-containing gas in a pressure swing adsorption unit 1 under the adsorption pressure of the heavy component gas relative to the hydrogen to obtain hydrogen-containing intermediate product gas;
(2) Contacting the hydrogen-containing intermediate product gas with a hydrogen storage alloy in a hydrogen absorption unit 2 to absorb hydrogen in the hydrogen-containing intermediate product gas;
(3) Under the analysis condition, analyzing the hydrogen absorbed in the step (2) to obtain a product gas;
(4) desorbing the heavy component gas which is adsorbed in the pressure swing adsorption unit 1 and is relative to hydrogen to regenerate the pressure swing adsorption unit 1 to obtain regenerated gas;
Wherein the hydrogen-containing gas contains the regeneration gas.
The process apparatus, process conditions and preferred embodiments for producing high purity hydrogen from hydrogen-containing gas have been described in detail above, and the present invention will not be described herein again in order to avoid unnecessary repetition.
The present invention will be described in detail below by way of examples.
Example 1
This example illustrates the process of the present invention for producing high purity hydrogen from a hydrogen-containing gas
The hydrogen-containing gas is a mixed gas composed of hydrogen and nitrogen, and specifically, the composition is 55% of hydrogen and 45% of nitrogen, which is described with reference to fig. 1.
(1) product gas backpressure
Before the start of the adsorption, the back gas can be completed by opening the valves V8 and V14 to allow part of the product gas to flow into the pressure swing adsorption unit 1 and reach the adsorption pressure of 1.5 MPa.
(2) Raw material gas adsorption
Closing the valve V14, opening the valves V1, V2 and V5 and the valve V12, leading the raw material gas to enter the pressure swing adsorption unit 1, leading the light component gas as the intermediate product gas such as hydrogen to enter the gas buffer tank 7 through the pressure swing adsorption unit 1, leading the heavy component gas molecules to be adsorbed to the concentration of the adsorbent, and finishing the adsorption process when the concentration front edge of the heavy component reaches about 1/3 parts of the tail end of the adsorbent bed layer.
Wherein the inlet pressure of the raw material gas is 1.5MPa, and the outlet pressure of the intermediate product gas is 1.5MPa, so that the adsorption pressure in the pressure swing adsorption unit 1 can be maintained, wherein the adsorbent is a 5A molecular sieve.
(3) hydrogen absorption purification
the valve V11 is opened to communicate the gas buffer tank 7 with the hydrogen absorption unit 2, the hydrogen and the hydrogen storage alloy in the hydrogen absorption unit 2 are rare earth series AB5 alloy, and the valve V11 is closed when the metal absorption reaches saturation.
(4) Hydrogen desorption
The valve V12 is opened to discharge the unabsorbed impurity gas remaining in the gas buffer tank 7 through the by-product gas line. At the same time, the valve V13 provided between the hydrogen absorption unit 2 and the hydrogen storage unit 3 is opened, and hydrogen is desorbed from the metal hydride at room temperature under 1MPa and is transferred to the hydrogen storage unit 3, thereby obtaining a high-purity hydrogen product.
(5) Pressure reduction of the adsorption tower
Valves V5 and V6 provided between the pressure swing adsorption unit 1 and the first gas recovery unit 5 are opened to communicate with each other, and the intermediate product gas of the adsorbent phase in the pressure swing adsorption unit 1 flows into the first gas recovery unit 5. When the pressures of the two pressure vessels are equal, the depressurization is finished.
(6) Purge regeneration
The product gas in the hydrogen storage unit 3 flows into the pressure swing adsorption unit 1 to purge and regenerate it by opening the valves V8 and V14 and the valves V5 and V7 provided between the pressure swing adsorption unit 1 and the second gas recovery unit 6: the regeneration gas is stored in the second gas recovery unit 6.
(7) The adsorption towers are all boosted
The valves V5 and V6 provided between the pressure swing adsorption unit 1 and the first gas recovery unit 5 are opened to communicate with each other, and the intermediate product gas in the first gas recovery unit 5 flows into the pressure swing adsorption unit 1. When the pressures of the two pressure vessels are equal, the pressure rise is finished.
(8) Gas recovery
The valves V6 and V3 provided between the first gas recovery unit 5 and the feed unit and V7 and V4 provided between the second gas recovery unit 6 and the feed unit were opened to re-compress the recovered gas and mix it with the feed gas, and the adsorption separation was performed again as the feed gas.
(9) By-product gas recovery
After several cycles, when the concentration of the heavy component gas in the feed gas reaches above 85%, the valve V10 is opened, and the product gas after the heavy component concentration is output as the byproduct gas.
In each step, except the opened valve, the other valves are in a closed state. And, one cycle is completed. The system returns to the initial state, and enters the first step again to start the secondary circulation. Since the purge gas is completely recovered and the concentration of hydrogen in the feed gas is changed, parameters such as the adsorption time, the pressure equalizing time, the opening of the pressure equalizing valve and the like in the second step are not completely the same in each cycle.
After the purification of the raw material gas is finished, the recovery rate of the hydrogen is 90 percent, and the purity is more than 99.999 percent.
example 2
This example illustrates the process of the present invention for producing high purity hydrogen from a hydrogen-containing gas
This is explained with reference to fig. 2.
The preparation of high purity hydrogen was carried out according to the procedure of example 1, except that,
in the step (1), the adsorption pressure is 2.5 MPa.
In the step (2), the hydrogen-containing gas is a mixed gas composed of hydrogen, carbon dioxide and nitrogen, and specifically comprises 75% of hydrogen, 5% of nitrogen and 20% of carbon dioxide; wherein, the inlet pressure of the raw material gas is 2.5MPa, and the outlet pressure of the intermediate product gas is 2.5MPa, so that the adsorption pressure in the pressure swing adsorption unit 1 can be maintained, wherein, the adsorbent is activated carbon and 5A molecular sieve.
In the step (3), the hydrogen and the hydrogen storage alloy in the hydrogen absorption unit 2 are titanium AB2 alloy, and the metal hydride is formed by reaction at room temperature and under the condition of 2.0 MPa.
In the step (4), the hydrogen desorption conditions comprise that the desorption pressure is lower than 2.0MPa at room temperature.
In the step (6), purging regeneration is replaced by vacuum regeneration, specifically, valves V5 and V7 arranged between the pressure swing adsorption unit 1 and the second gas recovery unit 6 are opened, the vacuum unit 8 is opened, and the gas in the pressure swing adsorption unit 1 is pumped out to the second gas recovery unit 6, so that the regeneration of the pressure swing adsorption unit 1 is realized.
After the purification of the raw material gas is finished, the recovery rate of the hydrogen is 95 percent, and the purity is more than 99.999 percent.
Example 3
This example illustrates the process of the present invention for producing high purity hydrogen from a hydrogen-containing gas
The production of high-purity hydrogen was carried out by carrying out the process according to example 2, except that the first gas recovery unit 5 and the second gas recovery unit 6 were not provided.
after the purification of the raw material gas is finished, the recovery rate of the hydrogen is 75 percent, and the purity is more than 99.999 percent.
example 4
This example illustrates the process of the present invention for producing high purity hydrogen from a hydrogen-containing gas
The production of high purity hydrogen was carried out by carrying out the process in accordance with example 2, except that the gas buffer tank 7 was not provided.
after the purification of the raw material gas is finished, the recovery rate of the hydrogen is 90 percent, and the purity is more than 99.999 percent.
Comparative example 1
This comparative example serves to illustrate a reference process for producing high purity hydrogen gas from a hydrogen-containing gas
The high purity hydrogen production was carried out by following the procedure of example 2, except that the hydrogen absorption unit 2 was not provided, that is, only pressure swing adsorption was carried out.
after the purification of the raw material gas is finished, the recovery rate of the hydrogen is 70 percent, and the purity is more than 99.99 percent.
comparative example 2
This comparative example serves to illustrate a reference process for producing high purity hydrogen gas from a hydrogen-containing gas
The high purity hydrogen production was carried out by the procedure of example 2, except that the pressure swing adsorption unit 1 was not provided, that is, only the hydrogen storage alloy absorption reaction of the raw material gas was carried out.
After the purification of the raw material gas is finished, the recovery rate of the hydrogen is 95 percent, and the purity is more than 99.999 percent.
Although the hydrogen recovery rate of comparative example 2 is close to that of example 2, the process of this comparative example is only suitable for further purification of hydrogen gas at a concentration of 99% or more, and for a low-concentration hydrogen-containing raw material gas, the process shortens the life of the hydrogen storage compound and hydrogen gas with a purity of 99.999% or more cannot be obtained.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. An apparatus for producing high purity hydrogen from a hydrogen-containing gas in an unsteady state, the apparatus comprising, in order from the direction of flow:
A hydrogen-containing gas supply unit (9);
The pressure swing adsorption unit (1) is used for carrying out pressure swing adsorption on heavy component gas relative to hydrogen in the hydrogen-containing gas from the hydrogen-containing gas supply unit (9) to obtain hydrogen-containing intermediate product gas;
a hydrogen absorption unit (2) for absorbing hydrogen in the hydrogen-containing intermediate product gas;
A hydrogen storage unit (3) for receiving the desorbed hydrogen from the hydrogen absorption unit (2);
And a regeneration gas return line (4) for sending the regeneration gas obtained by regenerating the pressure swing adsorption unit (1) to a hydrogen-containing gas supply unit (9), and mixing the regeneration gas with the gas contained therein as the hydrogen-containing gas.
2. the apparatus according to claim 1, wherein the apparatus further comprises a first gas recovery unit (5) for pressure swing adsorption unit (1) pressure equalization or pressure equalization;
Preferably, the apparatus further comprises a second gas recovery unit (6) for recovering a regeneration gas obtained after the regeneration of the pressure swing adsorption unit (1).
3. The apparatus according to claim 1 or 2, wherein the apparatus further comprises a gas buffer tank (7) arranged between the pressure swing adsorption unit (1) and the hydrogen absorption unit (2) for temporarily storing the hydrogen-containing intermediate product gas.
4. the apparatus according to any one of claims 1 to 3, wherein the apparatus further comprises an evacuation unit (8) arranged between the pressure swing adsorption unit (1) and the second gas recovery unit (5) for subjecting the heavy component gas adsorbed in the pressure swing adsorption unit (1) with respect to hydrogen to vacuum desorption to obtain the regeneration gas.
5. The apparatus according to any one of claims 1 to 3, wherein the pressure swing adsorption unit (1) is in communication with a hydrogen storage unit (3), the hydrogen storage unit (3) being adapted to supply hydrogen to the pressure swing adsorption unit (1) for desorbing the heavy component gas adsorbed in the pressure swing adsorption unit (1) with respect to hydrogen to obtain the regeneration gas.
6. A method for producing high purity hydrogen gas from a hydrogen-containing gas in an unsteady state, the method comprising:
(1) Adsorbing heavy component gas relative to hydrogen in the hydrogen-containing gas in a pressure swing adsorption unit (1) under the adsorption pressure of the heavy component gas relative to the hydrogen to obtain hydrogen-containing intermediate product gas;
(2) Contacting the hydrogen-containing intermediate product gas with a hydrogen storage alloy in a hydrogen absorption unit (2) to absorb hydrogen in the hydrogen-containing intermediate product gas;
(3) Under the analysis condition, analyzing the hydrogen absorbed in the step (2) to obtain a product gas;
(4) desorbing the heavy component gas which is adsorbed in the pressure swing adsorption unit (1) and is relative to hydrogen to regenerate the pressure swing adsorption unit (1) to obtain regenerated gas;
Wherein the hydrogen-containing gas contains the regeneration gas.
7. The method of claim 6, wherein the method further comprises:
(5) conveying the hydrogen-containing intermediate product gas remained in the pressure swing adsorption unit (1) to a first gas recovery unit (5), and uniformly depressurizing the pressure swing adsorption unit (1);
(6) Conveying the hydrogen-containing intermediate product gas in the first gas recovery unit (5) to the regenerated pressure swing adsorption unit (1), and uniformly boosting the pressure of the pressure swing adsorption unit (1);
Preferably, the hydrogen-containing gas further comprises a hydrogen-containing intermediate product gas from the first gas recovery unit (5) after the pressure of the intermediate product gas is increased.
8. The method according to claim 6 or 7, wherein in step (4), the pressure swing adsorption unit (1) is regenerated by desorbing the heavy component gas relative to hydrogen adsorbed in the pressure swing adsorption unit (1) using the product gas; or
The pressure swing adsorption unit (1) is regenerated by evacuating the pressure swing adsorption unit (1) and desorbing the adsorbed heavy component gas relative to hydrogen.
9. The method according to any one of claims 6 to 8, wherein in the step (1), the adsorption pressure of the heavy component gas with respect to hydrogen is 0.15 to 5 MPa;
preferably, the adsorbent in the pressure swing adsorption unit (1) is selected from activated carbon, molecular sieve, silica gel, carbon molecular sieve, activated alumina and various modified adsorbents.
10. The method according to any one of claims 6 to 8, wherein in step (2), the hydrogen storage alloy is selected from the group consisting of a rare earth-based hydrogen storage alloy, an AB-type titanium-based hydrogen storage alloy, a vanadium-based solid solution-type hydrogen storage alloy, a magnesium-based hydrogen storage alloy, and an AB 2-type Laves phase titanium-based hydrogen storage alloy; and/or
In the step (3), the analysis mode comprises room temperature reduced pressure analysis, temperature rising reduced pressure analysis and vacuum analysis.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114300719A (en) * | 2021-12-27 | 2022-04-08 | 中汽创智科技有限公司 | Hydrogen recovery unit and fuel cell system test rack |
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