Pressure swing adsorption hydrogen extraction desorption gas recycling system and method

Abstract

According to the pressure swing adsorption hydrogen extraction desorption gas recycling system and method provided by the invention, the idle pressure swing adsorption device is added to adsorb and treat the desorption gas generated by pressure swing adsorption hydrogen extraction, so that hydrogen in the desorption gas is recycled, and the hydrogen productivity is improved; and the problem of load increase of conversion and methanol washing processes can be solved, and the overall energy consumption of the system is reduced. When the idle pressure swing adsorption device adsorbs and treats the desorption gas generated by pressure swing adsorption hydrogen extraction, generated impurity gas with higher concentration can be used as fuel to replace original fuel gas of a combustion furnace, resource recycling is achieved, and gas consumption is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas recycling, and relates to a pressure swing adsorption hydrogen extraction and decomposition gas recycling system and method. Background Art

[0002] After the raw coal gas from the gasifier undergoes a shift process, the CO in the raw coal gas is converted to CO2, forming shifted gas. This shifted gas is then scrubbed in a methanol step to remove CO2 and H2S. The resulting purified gas is then fed to a pressure swing adsorption unit. Within the unit, a composite adsorption bed composed of multiple adsorbents selectively adsorbs the purified gas, removing nearly all impurities except hydrogen in one go. This results in product hydrogen with a purity exceeding 99.5%, completing the pressure swing adsorption hydrogen extraction process.

[0003] During adsorbent regeneration in a pressure swing adsorption unit, desorption gas is produced, containing 85% H₂, 12% CO, and 3% other impurities. Typically, this desorption gas is pressurized by a desorption gas compressor and then sent to the inlet of the shift process for recovery. However, this increases the operating load of the shift and methanol wash processes. Furthermore, the shift reaction requires additional water vapor, increasing overall system energy consumption. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and method for recycling desorption gas by pressure swing adsorption hydrogen extraction, so as to solve the problem of high energy consumption in existing desorption gas processing.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present application provides a method for reusing decomposed gas by extracting hydrogen through pressure swing adsorption, which comprises compressing the decomposed gas generated in a pressure swing adsorption device with a compressor and then sending it to an idle pressure swing adsorption device. After the idle pressure swing adsorption device adsorbs the decomposed gas, the generated hydrogen is mixed with the purified gas of raw coal gas at the outlet of a methanol washing and degassing device to form synthesis gas.

[0006] Preferably, the volume ratio of the hydrogen to CO in the purified raw coal gas is 1.02-1.04:1.

[0007] Preferably, the compressor compresses the analyzed gas to 3.0 MPa.

[0008] Preferably, the pressure of the hydrogen is 2.8 MPa and the purity is 99.9%.

[0009] The present application also provides a pressure swing adsorption hydrogen extraction and degassing reuse system, which includes a methanol washing and purification gas device, a pressure swing adsorption device, a compressor and an idle pressure swing adsorption device connected in sequence, and the idle pressure swing adsorption device is also connected to the outlet of the methanol washing and purification gas device.

[0010] Preferably, it further comprises a conversion device and a methanol-washed raw gas device, the conversion device is connected to the methanol-washed raw gas device, and the methanol-washed raw gas device and the idle pressure swing adsorption device are both connected to the methanol-washed raw gas device.

[0011] Preferably, the idle pressure swing adsorption device is also connected to a combustion furnace.

[0012] The present invention has the following beneficial effects: This application adds an idle pressure swing adsorption unit to adsorb and treat the desorbed gas produced by pressure swing adsorption hydrogen extraction. This not only recovers the hydrogen in the desorbed gas and increases hydrogen production capacity, but also addresses the increased load in the conversion and methanol wash processes and reduces overall system energy consumption. The higher concentration of impurity gases produced by the idle pressure swing adsorption unit during adsorption treatment of the desorbed gas produced by pressure swing adsorption hydrogen extraction can be used as fuel to replace the raw fuel gas in the combustion furnace, achieving resource reuse and saving gas consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural diagram of the pressure swing adsorption hydrogen extraction and decomposition gas reuse system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0015] An embodiment of the present application provides a method for reusing decomposed gas from a pressure swing adsorption device for hydrogen extraction, the method comprising: the decomposed gas generated in the pressure swing adsorption device is compressed by a compressor and then fed into an idle pressure swing adsorption device; after the idle pressure swing adsorption device adsorbs the decomposed gas, the generated hydrogen is mixed with the purified gas of the raw coal gas at the outlet of the methanol scrubbing gas purification device to form synthesis gas.

[0016] Specifically, when the adsorbent in the pressure swing adsorption unit regenerates, it produces desorption gas at a pressure of 0.02 MPa, containing 85% H₂, 12% CO, and 3% other impurities. This desorption gas is compressed to 3.0 MPa by a compressor and then fed into an idle pressure swing adsorption unit. The adsorption tower in the idle pressure swing adsorption unit further adsorbs the desorption gas, producing hydrogen at a pressure of 2.8 MPa and 99.9% purity, along with impurities with a higher impurity concentration. This hydrogen is mixed with the purified raw coal gas from the methanol scrubbing unit to form synthesis gas. The volume ratio of hydrogen to CO in this synthesis gas is 1.02-1.04:1, and this synthesis gas is fed to downstream units for use, recycling the hydrogen in the desorption gas, increasing hydrogen production capacity while reducing overall energy consumption. The impurity gas discharged from the adsorption tower is fed to the incinerator for use as fuel, replacing the incinerator's raw fuel gas, thus reusing resources.

[0017] In addition, the embodiment of the present application also provides a pressure swing adsorption hydrogen extraction and decomposition gas reuse system, which includes a methanol washing and purification gas device, a pressure swing adsorption device, a compressor and an idle pressure swing adsorption device connected in sequence, and the idle pressure swing adsorption device is also connected to the outlet of the methanol washing and purification gas device, as shown in the attached Figure 1 shown.

[0018] Among them, the methanol washing and purification gas device is a component that uses atmospheric methanol to wash the conversion gas in order to remove CO2 and H2S therein to form purified gas.

[0019] The pressure swing adsorption unit performs composite adsorption on the purified gas produced by the methanol scrubbing and purification unit, removing almost all impurities except hydrogen at once, directly producing product hydrogen with a purity greater than 99.5%. This hydrogen is then sent to downstream units for use.

[0020] After the pressure swing adsorption unit adsorbs the purified gas, the adsorbent is regenerated, producing desorbed gas. This desorbed gas is then fed into a compressor and compressed to 3.0 MPa. The compressed desorbed gas is then fed into an idle pressure swing adsorption unit, where the adsorption tower further adsorbs the desorbed gas, producing hydrogen at a pressure of 2.8 MPa and a purity of 99.9%, along with impurities. This hydrogen is then mixed with the purified raw coal gas from the methanol scrubbing unit to form synthesis gas. The volume ratio of hydrogen to CO in this synthesis gas is 1.02-1.04:1, and this synthesis gas is then fed to downstream units for use, allowing the hydrogen in the desorbed gas to be recovered and reused, increasing hydrogen production capacity while reducing overall energy consumption.

[0021] In addition, the pressure swing adsorption hydrogen extraction and degassing reuse system provided in the embodiment of the present application also includes a conversion device and a methanol raw gas washing device. The conversion device is connected to the methanol raw gas washing device, and the methanol raw gas washing device and the idle pressure swing adsorption device are both connected to the methanol raw gas washing device.

[0022] Part of the raw gas produced by the gasifier is passed to the methanol-washed raw gas unit, while the remaining portion is passed to the shift unit. The shift unit converts the CO in the raw gas into CO2, producing shifted gas. This shifted gas is then passed to the methanol-washed gas purification unit, where low-temperature methanol removes CO2 and H2S from the converted gas, producing purified gas. Part of this purified gas is passed to the methanol-washed raw gas unit, while the remaining portion is passed to the pressure swing adsorption unit, where it is adsorbed into hydrogen. The desorption gas generated during adsorbent regeneration in the pressure swing adsorption unit is compressed by a compressor and discharged into an idle pressure swing adsorption unit for adsorption treatment. The resulting hydrogen is mixed with the purified gas from the methanol-washed gas purification unit and discharged into the methanol-washed raw gas unit for use in downstream units.

[0023] Furthermore, the pressure swing adsorption hydrogen extraction and decomposition gas reuse system provided in the embodiment of the present application also includes a combustion furnace, which is connected to an idle pressure swing adsorption device to burn the impurity gas discharged from the idle pressure swing adsorption device to replace the original fuel gas of the combustion furnace, thereby realizing resource recycling.

[0024] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for reusing decomposed gas by pressure swing adsorption to extract hydrogen, characterized in that: include: The desorption gas generated in the pressure swing adsorption device is compressed by a compressor and then sent to an idle pressure swing adsorption device. After the idle pressure swing adsorption device adsorbs the desorption gas, the generated hydrogen is mixed with the raw coal gas purification gas at the outlet of the methanol washing and purification device to form synthesis gas.

2. The method for extracting hydrogen by pressure swing adsorption and reusing decomposed gas according to claim 1, characterized in that: The volume ratio of the hydrogen to the CO in the purified raw coal gas is 1.02-1.04:

1.

3. The method for extracting hydrogen by pressure swing adsorption and reusing decomposed gas according to claim 1, characterized in that: The compressor compresses the desorption gas to 3.0 MPa.

4. The method for extracting hydrogen by pressure swing adsorption and reusing decomposed gas according to claim 1, characterized in that: The pressure of the hydrogen is 2.8 MPa and the purity is 99.9%.

5. A pressure swing adsorption hydrogen extraction and desorption gas recycling system, characterized in that: It comprises a methanol washing and purification gas device, a pressure swing adsorption device, a compressor and an idle pressure swing adsorption device which are connected in sequence, and the idle pressure swing adsorption device is also connected to the outlet of the methanol washing and purification gas device.

6. The pressure swing adsorption hydrogen extraction and desorption gas reuse system according to claim 5, characterized in that: It also includes a conversion device and a methanol-washed raw gas device. The conversion device is connected to the methanol-washed raw gas device. The methanol-washed raw gas device and the idle pressure swing adsorption device are both connected to the methanol-washed raw gas device.

7. The pressure swing adsorption hydrogen extraction and desorption gas reuse system according to claim 5, characterized in that: The idle pressure swing adsorption device is also connected to a combustion furnace.

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