Abstract
A full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas, includes a medium and high temperature PSA ammonia concentration system and an intermediate gas PSA hydrogen purification system, which include multiple axial flow fixed bed adsorption towers arranged in the center of upper and lower two multichannel rotary valves, mounted on the periphery of an annular rotary tray, and connected through pipelines. For the gas flowing through rotary valve channels, pipelines between inlet and outlet ends of the channels and inlet and outlet ends of the adsorption towers, and adsorption bed layers, mass transfer in respective adsorption and desorption steps is completed while the gas entering and exiting the inlets and outlets of the adsorption towers and adsorption bed layers while rotating. Thus, the simulated rotated moving bed PSA process is formed.
Claims
1. A full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas, wherein a full temperature range simulated rotated moving bed PSA (FTrSRMPSA) system comprises a multi-tower medium temperature PSA concentration system (comprising a driving mechanism) with n (4n40, a natural integer) adsorption towers, a multi-tower medium and low temperature intermediate gas PSA system (comprising a driving mechanism) with n (4n40, a natural integer) adsorption towers, an H.sub.2 product gas (H.sub.2PG)/feed gas (F)/intermediate gas (IG)/nitrogen-rich desorbed gas (N.sub.2D) buffer tank, a liquid ammonia product storage tank, a feed gas compressor 1/intermediate gas compressor 2, a feed gas heat exchanger 1 (heater)/ammonia concentrated gas heat exchanger 2 (cooler)/condenser freezer, as well as corresponding materials and process pipelines; a medium and high temperature PSA ammonia concentration system of n axial flow fixed composite bed adsorption towers (n adsorption towers for short) loaded with various adsorbents and having a certain height to diameter ratio and an intermediate gas PSA hydrogen purification system of n axial flow fixed composite bed adsorption towers (n adsorption towers for short) loaded with various adsorbents and having a certain height to diameter ratio are formed by the n adsorption towers and the n adsorption towers (i.e., n+n adsorption towers) arranged uniformly at intervals respectively on an annular rotary tray with a rotation speed of .sub.2 (second/revolution), the corresponding driving mechanisms, m (5m36, a natural integer) channels and m (5m36, a natural integer) channels arranged in the center of the annular tray, and the upper and lower two independently rotating multichannel rotary valves with the rotation speeds of .sub.1 (second/revolution) and .sub.1 (second/revolution) respectively; the upper rotary valve is called an m-channel rotary valve for short, and the lower rotary valve is called an m-channel rotary valve for short; inlet and outlet ends of the m- and m-channels are respectively connected to inlets and outlets of the m-/m-channel rotary valves, inlets and outlets of internal pipelines of the rotary tray, and inlet and outlet ends of the n/n adsorption towers through material and process pipelines that are respectively connected to the internal pipelines of the annular rotary tray and the inlet and outlet ends of corresponding n adsorption towers/n adsorption towers and connected to the H.sub.2 product gas/feed gas/intermediate gas/nitrogen-rich desorbed gas buffer tanks and the feed gas compressor 1/heat exchanger 1/intermediate gas compressor 2/ammonia concentrated gas heat exchanger 2/ammonia condenser freezer; the process flow is as follows: the exhaust gas generated in a GaN-MOCVD epitaxial process is used as feed gas (F), which typically comprises the following main components: 55% (v/v, similar below) of hydrogen (H.sub.2), 25% of nitrogen (N.sub.2), 20% of ammonia (NH.sub.3), and the balance of small or trace amounts of metal ions, particulate matter, methane (CH.sub.4), oxygen (O.sub.2), and oxides comprising carbon monoxide (CO), carbon dioxide (CO.sub.2) and water (H.sub.2O) at a temperature of 25-40 C. and a normal or slightly positive pressure; the feed gas (F) flowing out of the feed gas buffer tank, which is heated by the heat exchanger 1 to 80-120 C. and pressurized by the compressor 1 to 0.6-0.8 MPa, enters the channels of the m-channel rotary valve in the medium and high temperature PSA ammonia concentration system and the internal pipelines of the annular rotary tray to enter a certain adsorption tower of the n adsorption towers, for medium and high temperature PSA ammonia concentration; ammonia concentrated gas (NH.sub.3CG) consisting of ammonia-rich depressurization gas (NH.sub.3D) and ammonia-rich purge waste gas (NH.sub.3PW) continuously produced from the system has an ammonia concentration of greater than or equal to 90-95%, and is cooled to 25-40 C. by the heat exchanger 2 before entering an ammonia condensation and refrigeration unit; a resulting condensate is a liquid ammonia product (NH.sub.3PL), which has a concentration of 99.99-99.999% and a yield of 98-99%, and is fed into a liquid ammonia product tank; resulting non-condensable gas enters an intermediate gas (IG) buffer tank as low pressure intermediate gas (LPIG), and non-adsorbed phase gas flowing out of the medium and high temperature PSA ammonia concentration system enters the intermediate gas (IG) buffer tank as low pressure intermediate gas (LPIG), flows out of the buffer tank together with the non-condensable gas as the low pressure intermediate gas (LPIG), and is pressurized by the intermediate gas (IG) compressor 2 to 2.0-3.0 MPa to form high pressure intermediate gas (HPIG); the high pressure intermediate gas (HPIG) enters the channels of the m-channel rotary valve of the intermediate gas PSA hydrogen purification system, and enters a certain adsorption tower of the n adsorption towers through an internal pipeline of the annular rotary tray, for intermediate gas PSA hydrogen purification; a non-adsorbed phase hydrogen gas product (H.sub.2PG) is continuously produced from the system, and has a purity of 99.99-99.999% and a yield of 92-95%; nitrogen-rich desorbed gas (N.sub.2D) of the absorbed phase continuously flowing out of the system enters the nitrogen-rich desorbed gas (N.sub.2D) buffer tank and flows out, or is directly discharged, or is subjected to cryogenic nitrogen production and H.sub.2 recovery, or undergoes membrane separation for H.sub.2 recovery; thus, a complete full temperature range simulated rotated moving bed PSA (FTrSRMPSA) separation and purification process for producing high-purity and high-yield H.sub.2 and NH.sub.3 from GaN-MOCVD process exhaust gas as the feed gas is formed; and high-purity H.sub.2 product gas (H.sub.2PG) with a purity greater than or equal to 99.99% and a yield greater than or equal to 92%, and a liquid ammonia product (NH.sub.3PL) with a purity greater than or equal to 99.99% and a yield greater than or equal to 98% are obtained from the GaN-MOCVD process exhaust gas, and returned to the GaN-MOCVD process for recycling.
2. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein regulation and matching of rotation directions of the m- and m-channel rotary valves and the annular rotary tray in the medium and high temperature PSA ammonia concentration system and the intermediate gas PSA hydrogen purification system and rotation speeds (.sub.1, .sub.1 and .sub.2) thereof comprise: 1) synchronization in the same direction, i.e., rotating clockwise or counterclockwise in the same direction, with .sub.1=.sub.1=.sub.2/0, and 2) asynchronization in the same direction, i.e., rotating clockwise or counterclockwise in the same direction, with either .sub.10.sub.10/.sub.2=0, or .sub.10.sub.10/.sub.2=0, or .sub.1=.sub.1=0/.sub.20, preferably, asynchronization in the same direction, i.e., rotating clockwise or counterclockwise in the same direction with .sub.10.sub.1/.sub.2=0.
3. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein the n adsorption towers in the medium and high temperature PSA ammonia concentration system sequentially and alternately go through adsorption and desorption cycle operation steps of adsorption (A), equalization drop (ED)/purge pressurization (PP), depressurization (D)/purge (P), equalization rise (ER)/waiting area (-), and final repressurization (FR); the maximum number of times of pressure equalization is 2, comprising first equalization drop (E1D)/first equalization rise (E1R) and second equalization drop (E2D)/second equalization rise (E2R); the steps of purge pressurization (PP) and waiting (-) need to be flexibly arranged according to the alternating timing of each adsorption tower during the PSA cycle operations; the n adsorption towers sequentially and alternately going through the PSA cycle operation steps is achieved by regulation and matching of rotation directions of the m-channel rotary valve and the annular rotary tray in the medium and high temperature PSA ammonia concentration system, and rotation speeds (.sub.1 and .sub.2) thereof, and each channel in the m-channel rotary valve alternately switching materials and process gas flowing in the PSA cycle operation process at regular intervals to enter the n adsorption towers to perform the PSA cycle operations.
4. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein the n adsorption towers in the intermediate gas PSA hydrogen purification system sequentially and alternately go through adsorption and desorption cycle operation steps of adsorption (A), equalization drop (ED)/purge pressurization (PP), depressurization (D)/purge (P), equalization rise (ER)/waiting area (-), and final repressurization (FR); the maximum number of times of pressure equalization is 3, comprising first equalization drop (E1D)/first equalization rise (ER), second equalization drop (E2D)/second equalization rise (E2R), and third equalization drop (E3D)/third equalization rise (E3R); the steps of purge pressurization (PP) and waiting (-) need to be flexibly arranged according to the alternating timing of each adsorption tower during the PSA cycle operations; the n adsorption towers sequentially and alternately going through the PSA cycle operation steps is achieved by regulation and matching of rotation directions of the m-channel rotary valve and the annular rotary tray in the intermediate gas PSA hydrogen purification system and rotation speeds (.sub.1 and .sub.2) thereof, and each channel in the m-channel rotary valve alternately switching materials and process gas flowing in the PSA cycle operation process at regular intervals to enter the n adsorption towers to perform the PSA cycle operations.
5. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein purge gas (P) in the medium and high temperature PSA ammonia concentration system and the intermediate gas PSA hydrogen purification system which is either the purge pressurization gas (PP)/intermediate gas (IG) from inside the system, or the H.sub.2 product gas (H.sub.2PG)/ammonia concentrated gas (NH.sub.3CG) from outside the system is used to purge in batches through one or more openings in the rotary valve channels (conduits), with a maximum of 4 openings, preferably the purge pressurization gas (PP) from inside the system is used as the purge gas (P).
6. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein the depressurization (D) step in the medium and high temperature PSA ammonia concentration system and the intermediate gas PSA hydrogen purification system is performed by vacuumizing for desorption; an added vacuum pump is either connected to a stream pipeline for the desorbed gas (D) outflow from the rotary valve, or directly connected to an external pipeline connected to an outlet end of the adsorption tower on the annular rotary tray, with a control valve installed on the external pipeline, preferably, the added vacuum pump is directly connected to an external pipeline connected to the outlet end of the adsorption tower on the annular rotary tray, with a control valve installed on the external pipeline.
7. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein final repressurization gas (FR) in the PSA cycle operation of the medium and high temperature PSA ammonia concentration system and the intermediate gas PSA hydrogen purification system is either the feed gas (F), or the intermediate gas (IG), or the ammonia concentrated gas (NH.sub.3CG), or the H.sub.2 product gas (H.sub.2PG), from outside the system; and when the purity of the H.sub.2 product gas (H.sub.2PG) is greater than 99.99%, the final repressurization gas (FR) is preferably the H.sub.2 product gas (H.sub.2PG).
8. The full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas according to claim 1, wherein the n adsorption towers and the n adsorption towers of the medium and high temperature PSA ammonia concentration system and the intermediate gas PSA hydrogen purification system are respectively loaded with one or more combined adsorbents of active calcium chloride, activated carbon, and molecular sieves, and one or more combined adsorbents of aluminum oxide, silica gel, activated carbon, molecular sieves, and carbon molecular sieves, preferably, the adsorption towers in the two systems are loaded with two or more combined adsorbents to form composite adsorbent bed layers.
Description
BRIEF DESCRIPTION OF FIGURES
[0021] FIG. 1 is a flowchart of Example 1 of the disclosure.
[0022] FIG. 2 is a flowchart of Example 2 of the disclosure.
[0023] FIG. 3 is a flowchart of Example 3 of the disclosure.
DETAILED DESCRIPTION
[0024] For those skilled in the art to better understand the disclosure, the technical solutions in the examples of the disclosure will be clearly and completely described below with reference to the accompanying drawings in the examples of the disclosure.
Example 1
[0025] As shown in FIG. 1, in a full temperature range simulated rotated moving bed PSA process for extracting H.sub.2 and NH.sub.3 from GaN-MOCVD exhaust gas, the full temperature range simulated rotated moving bed PSA FTrSRMPSA system includes 4 axial flow fixed composite bed layer adsorption towers loaded with molecular sieves and activated carbon (n=4) with a height to diameter ratio of 3 and 5 axial flow fixed composite bed layer adsorption towers loaded with aluminum oxide, silica gel, activated carbon, molecular sieves/carbon molecular sieves (n=5) with a height to diameter ratio of 4, adsorption towers (n+n=9) and corresponding driving mechanisms arranged on an annular rotary tray with a rotation speed of .sub.2=0, upper and lower two independent rotating rotary valves rotating at rotation speeds of .sub.1=320-400 s and .sub.1=210-300 s respectively with a channel number of (m=6 and m=7) and arranged in the center of the annular tray, a feed gas (F) compressor 1 and intermediate gas (IG) compressor 2, an ammonia concentrated gas (NH.sub.3CG) condenser cooler, and a feed gas (F)/intermediate gas (IG)/H.sub.2 product gas (H.sub.2PG)/nitrogen-rich desorbed gas (N.sub.2D) buffer tank. The m-/m-channel rotary valves are connected to the feed gas (F), the H.sub.2 product gas (H.sub.2PG), high/low pressure intermediate gas (H/LPIG), final repressurization gas of product hydrogen/feed gas (FR of H.sub.2/F), ammonia concentrated gas (NH.sub.3CG) consisting of ammonia-rich depressurization gas (NH.sub.3D) and ammonia-containing purge waste gas (NH.sub.3PW), non-condensable gas, and nitrogen-rich desorbed gas (N.sub.2D) consisting of nitrogen-rich depressurization gas (D). The FTrSRMPSA system is formed by connecting inlets and outlets of the m-/m-channel rotary valves with the hydrogen product gas (H.sub.2PG), feed gas (F), high/low pressure intermediate gas (H/LPIG) buffer tank, and the material and process gas inlets and outlets of the ammonia concentrated gas (NH.sub.3CG) condenser cooler, and process pipelines connected to internal pipelines of the annular rotary tray and the n/n adsorption towers between the upper and lower m-/m-channel rotary valves. The rotation speed .sub.1 of a 7-channel rotary valve (upper) is 210-300 s, the rotation speed .sub.1 of a 6-channel rotary valve (lower) is 320-400 s, and the rotation speed .sub.2 of the annular rotary tray is 0. Of the 6 channels in the 6-channel rotary valve, one channel (m=4) is for pressurized feed gas (F), one shared channel (m=3) with 2 through holes is for low-pressure intermediate gas (LPIG), one shared channel (m=5) is for equalization drop (ED) and equalization rise (ER) of the concentrated ammonia adsorbed phase, one shared channel (m=6) is for purge pressurization gas (PP) and purge gas (P) of the concentrated ammonia adsorbed phase, one shared channel with 2 through holes (m=2) is for ammonia concentrated gas (NH.sub.3CG) formed by the concentrated ammonia adsorbed phase depressurization gas (NH.sub.3D) and ammonia-containing purge waste gas (NH.sub.3PW), and one shared channel (m=1) is for the final repressurization gas (FR) of the pressurized feed gas (F) as the final repressurization gas (FR). Of the 7 channels in the 7-channel rotary valve, one channel (m=4) is for pressurized high pressure intermediate gas (HPIG), one channel (m=3) is for the hydrogen product gas (H.sub.2PG), one shared channel (m=2) is for the first equalization drop (E1D) and equalization rise (EIR) of the nitrogen-containing adsorbed phase, one shared channel (m=5) is for the second equalization drop (E2D) and equalization rise (E2R) of the nitrogen-containing adsorbed phase, one shared channel (m=6) is for purge waste gas (N.sub.2PW) formed by hydrogen-containing purge pressurization gas (PP) as nitrogen-containing adsorbed phase purge gas (P) and is shared with the m=3 channel, one channel (m=1) is for nitrogen-rich desorbed gas (N.sub.2D) formed by nitrogen-rich depressurization gas (N.sub.2D), and one channel (m=7) is for final repressurization gas (FR) of the hydrogen product gas (H.sub.2PG) as the final repressurization gas (FR). Nitrogen-rich desorbed gas (N.sub.2D) flowing out of an outlet end of the m-channel rotary valve flows through a material pipeline connected to the nitrogen-containing desorbed gas (N.sub.2D) buffer tank, enters the buffer tank, or is directly discharged. Ammonia concentrated gas (NH.sub.3CG) formed by ammonia-containing depressurization gas (D) flowing out of an outlet end of the m-channel rotary valve and ammonia-containing purge waste gas (NH.sub.3PW) flows through a material pipeline connected to a heat exchanger 2 (cooler) and a condenser freezer. Low pressure intermediate gas (LPIG) flowing out of the outlet end of the m-channel rotary valve flows through a material pipeline connected to an intermediate gas (IG) buffer tank, a compressor 2, and a high pressure intermediate gas (HPIG) inlet end of the m-channel rotary valve. The condensate flowing out of the condenser freezer is a liquid ammonia product (NH.sub.3PL), and non-condensable gas flows through a material pipeline connecting a non-condensable gas outlet end of the condenser freezer and an inlet of the intermediate gas (IG) buffer tank. The hydrogen product gas (H.sub.2PG) flowing out of the outlet end of the m-channel rotary valve flows through a material pipeline connected to a hydrogen product gas (H.sub.2PG) buffer tank. Hydrogen-containing final repressurization gas (H.sub.2FR) flowing into an inlet end of the m-channel rotary valve flows through a material pipeline connecting the hydrogen product gas (H.sub.2PG) buffer tank and a corresponding channel inlet end of the rotary valve. Ammonia-containing final repressurization gas (NH.sub.3FR) flowing into an inlet end of the m-channel rotary valve flows through a material pipeline connected to a feed gas (F) buffer tank, a heat exchanger 1 (heater) and a compressor 1. The feed gas (F) is epitaxial exhaust gas from a gallium nitride metal oxide chemical vapor deposition (GaN-MOCVD) epitaxial process, which typically includes components of 55% of hydrogen (H.sub.2), 25% of nitrogen (N.sub.2), and 20% of ammonia (NH.sub.3) at room temperature and pressure. The feed gas (F) enters a material channel of the m-channel rotary valve feed gas (F) (e.g., m=4), through a material pipeline connected to the feed gas (F) buffer tank, the heat exchanger 1 (for heating to 80-120 C.), the feed gas (F) compressor 1 (for pressurizing to 0.6-0.8 MPa), and an inlet through-hole of the rotary valve channel. Further, the feed gas (F) flows through a process pipeline formed by connecting an outlet of the channel to an internal pipeline of the annular tray and to an inlet end of an adsorption tower 1, and enters the adsorption tower 1 to perform a low pressure adsorption (LA) step, where the adsorption pressure is 0.6-0.8 MPa and the adsorption temperature is 80-120 C. NH.sub.3 in the feed gas (F) is adsorbed and concentrated as an adsorbate. H.sub.2 and N.sub.2 are non-adsorbed phase gas, flow out as intermediate gas (IG) from an outlet end of adsorption tower 1, and flow through a process pipeline connected to the adsorption tower 1, an internal pipeline of the annular rotary tray, and a through hole of a material channel of the m-channel rotary valve (e.g., m=3). The intermediate gas (IG) flows out from the outlet end of the m-channel rotary valve, enters a low pressure intermediate gas (LPIG) buffer tank, and is pressurized by an intermediate gas (IG) compressor 2 to 2-3 MPa as feed gas of the adsorption tower 1. While a low pressure adsorption (LPA) step is performed in the adsorption tower 1, the pressurized high pressure intermediate gas (HPIG) as the feed gas flows through a material pipeline connected to a through hole at a channel inlet of the m-channel rotary valve (e.g., m=4). As the m-channel rotary valve rotates clockwise, the high pressure intermediate gas (HPIG) flows through a process pipeline formed by connecting an outlet of the channel to the internal pipeline of the annular tray and to an inlet end of the adsorption tower 1 to enter the adsorption tower 1 to perform a high pressure adsorption (HPA) step, where the adsorption pressure is 2-3 MPa, and adsorbates are nitrogen (N.sub.2), a small amount of ammonia (NH.sub.3), and hydrogen (H.sub.2) remaining in a dead space of an adsorption tower 2. Non-adsorbed phase gas flows out from an outlet end of adsorption tower 1, and flows through a process pipeline connected to the adsorption tower 1, an internal pipeline of the annular rotary tray, and a through hole of a material channel of the m-channel rotary valve (e.g., m=3). The non-adsorbed phase gas flows out from the outlet end of the m-channel rotary valve as the hydrogen product gas (H.sub.2PG) and is input into the hydrogen product gas (H.sub.2PG) buffer tank, where the hydrogen product gas (H.sub.2PG) has a purity greater than or equal to 99.99%, and a pressure of 2-3 MPa. The hydrogen product gas (H.sub.2PG) is either output, or purified in a hydrogen purification section of the gallium nitride epitaxial production process and then returned to the GaN-MOCVD epitaxial process for recycling. While the high pressure adsorption (HPA) step is performed in the adsorption tower 1, process and material pipelines connecting the m-channel rotary valve to the adsorption tower 1 that ends the low pressure adsorption (LPA) step are synchronously rotated clockwise with the m-channel rotary valve to the position of an adsorption tower 2 (n=2) in FIG. 1, and are abutted against the adsorption tower 2, such that the adsorption tower 2 enters equalization drop (ED) and purge pressurization (PP) steps of the ammonia concentrate adsorbed phase. Resulting equalization drop gas (ED) flows through a shared channel in the m-channel rotary valve (e.g., m=5) and a process pipeline connected to a corresponding internal pipeline of the annular rotary tray and an adsorption tower 4, to perform pressure equalization on the adsorption tower 4 (n=4) in an equalization rise (ER) step of the ammonia concentrate adsorbed phase, where the pressure inside the adsorption tower 2 drops to 0.3-0.4 MPa. The purge pressurization gas (PP) generated by purge pressurization (PP) flows through a shared channel in the m-channel rotary valve (e.g., m=6) and a process pipeline connected to a corresponding internal pipeline of the annular rotary tray and an adsorption tower 3, to purge the adsorption tower 3 (n=3) in a purge (P) step of the ammonia concentrate adsorbed phase. While the purge pressurization (PP) and purge (P) steps of the ammonia concentrate adsorbed phase are performed in the adsorption tower 2, as the m-channel rotary valve synchronously rotates clockwise to the position of an adsorption tower 2 (n=2) as shown in FIG. 1, the adsorption tower 2 enters first equalization drop (E1D), second equalization drop (E2D), and purge pressurization (PP) steps of the nitrogen-rich adsorbed phase. Resulting first equalization drop gas (E1D) and second equalization drop gas (E2D) flow through a shared channel in the m-channel rotary valve (e.g., m=2 and 5) and a process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 2, to perform pressure equalization on an adsorption tower 4 (n=4) in the first and second equalization rise (E1R and E2R) steps of the ammonia-containing adsorbed phase, where the pressure inside the adsorption tower 2 drops to 0.3-0.4 MPa. The purge pressurization gas (PP) generated by purge pressurization (PP) flows through a shared channel in the m-channel rotary valve (e.g., m=6) and a process pipeline connected to a corresponding internal pipeline of the annular rotary tray and an adsorption tower 3, to purge the adsorption tower 3 (n=3) in a purge (P) step of the ammonia-containing adsorbed phase. As the m-channel rotary valve synchronously rotates clockwise to the position of the adsorption tower 3 (n=3) as shown in FIG. 1, the adsorption tower 3 enters depressurization (D) and purge (P) steps of the nitrogen-containing adsorbed phase. Depressurization gas (D) as the nitrogen-rich desorbed gas (N.sub.2D) flows through a shared channel in the m-channel rotary valve (e.g., m=1), and a material and process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 3. The nitrogen-rich desorbed gas (N.sub.2D) flows out from an outlet end of an m=1 channel of the m-channel rotary valve and enters the nitrogen-rich desorbed gas (N.sub.2D) buffer tank before being discharged. Then, purge pressurization gas (PP) generated from the adsorption tower 2 in the purge pressurization (PP) step is used as purge gas (P) for purging the adsorption tower 3 in the purge (P) step (P). Resulting nitrogen-containing purge waste gas (N.sub.2PW) as low pressure intermediate gas (LPIG) flows through one through hole of a shared channel that is located exactly in the n-channel rotary valve (e.g., m=3), has 2 through holes and is for intermediate gas (IG), and a material and process pipeline connected to a corresponding internal pipeline of the annular rotating tray and the adsorption tower 3, flows out from an outlet end of an m=3 channel of the m-channel rotary valve, and enters the low pressure intermediate gas (IG) buffer tank for recycling. While corresponding desorption steps are performed in the adsorption towers 2 and 3 with n=2 and n=3 of the nitrogen-containing adsorbed phase, as the m-channel rotary valve rotates clockwise to the position of the adsorption tower 3 (n=3) as shown in FIG. 1, the adsorption tower 3 enters depressurization (D) and purge (P) steps of the ammonia concentrate adsorbed phase. Ammonia-rich (concentrated) depressurization gas (NH.sub.3D) generated by depressurization (D) and following ammonia-rich purge waste gas (NH.sub.3PW) generated after purging (P) with ammonia-containing purge pressurization gas (PP) flowing out of the adsorption tower 2 in a purge pressurization (PP) step, as the ammonia concentrated gas (NH.sub.3CG), flow through a shared channel in the n-channel rotary valve (e.g., m=2) and a material and process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 3, flow out from an outlet end of a 2 channel of the n-channel rotary valve, and pass through the heat exchanger 2 (cooler) and the condenser freezer to form a condensate which is a liquid ammonia product (NH.sub.3PL) with an ammonia purity of 99.99% or higher, and is output for use. The formed non-condensable gas flows through a material pipeline and returns to the low pressure intermediate gas (IG) buffer tank for recycling. While a corresponding desorption step of the ammonia-containing adsorbed phase is performed in the adsorption tower 3, as the m-channel rotary valve rotates clockwise to the position of the adsorption tower 4 (n=4) as shown in FIG. 1, the adsorption tower 4 enters second equalization rise (E2R) and first equalization rise (E1R) steps of the nitrogen-containing adsorbed phase. First and second equalization rise (E1R and E2R) is performed sequentially in the adsorption tower 2 in the steps of first equalization drop (E1D) and second equalization drop (E2D). Shared channels in the m-channel rotary valve used are m=2 and m=5, respectively. While the second equalization rise (E1R and E2R) steps and waiting in a waiting area are performed in the adsorption tower 4, as the m-channel rotary valve rotates clockwise to the position of the adsorption tower 4 (n=4) as shown in FIG. 8, the adsorption tower 4 enters equalization rise (ER) and final repressurization (FR) steps of the ammonia-containing adsorbed phase. Equalization drop gas (ED) generated by the adsorption tower 2 in an equalization drop (ED) step of the ammonia-containing adsorbed phase flows through a shared channel of the m-channel rotary valve (e.g., m=5), and a material and process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 4 for pressure equalization in the adsorption tower 4, and then feed gas (F) is used as final repressurization gas (FR) and flows through a channel of the m-channel rotary valve (e.g., m=1) and a material and process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 4 for final repressurization (FR) in the adsorption tower 4 to achieve an adsorption pressure of 0.6-0.8 MPa in the adsorption tower 4 required for a low pressure adsorption (LPA) step. Thus, a complete closed-loop PSA cycle operation of the ammonia concentrate adsorbed phase is achieved in the adsorption tower 1, i.e., the following steps: low pressure adsorption (LPA), equalization drop (ED)/purge pressurization (PP), depressurization (D)/purge (P), and equalization rise (ER)/final repressurization (FR). Then, the adsorption tower 1 enters a next closed-loop cycle operation process of adsorption and desorption. While the m-channel rotary valve continuously rotates during the closed-loop cycle operation process of adsorption and desorption in the adsorption tower 1, corresponding material gas and process gas entering and exiting the adsorption towers 2, 3 and 4 are switched between entry and exit positions to perform the corresponding closed-loop cycle operation steps of adsorption and desorption. The closed-loop cycle operation steps of each of the 4 (n=4) adsorption towers correspond to the closed-loop cycle operation steps of each of the other 3 adsorption towers. As a result, a liquid ammonia product (NH.sub.3PL) with an ammonia concentration greater than or equal to 99.99% (v/v) is continuously produced from the GaN-MOCVD process exhaust gas as the feed gas, and the yield of the liquid ammonia product is 98-99%. Meanwhile, during the final repressurization (FR) in the adsorption tower 4, as the m-channel rotary valve rotates clockwise to the position of the adsorption tower 5 (n=5) as shown in FIG. 1, the adsorption tower 5 enters a final repressurization (FR) step of the nitrogen-rich adsorbed phase. Hydrogen product gas (H.sub.2PG) is used as final repressurization gas (FR) and flows through a channel of the m-channel rotary valve (e.g., m=7) and a material and process pipeline connected to a corresponding internal pipeline of the annular rotary tray and the adsorption tower 5 for final repressurization (FR) in the adsorption tower 5 to achieve an adsorption pressure of 2-3 MPa in the adsorption tower 5 required for a high pressure adsorption (HPA) step. Thus, a complete closed-loop PSA cycle operation of the nitrogen-containing adsorbed phase is achieved in the adsorption tower 1, i.e., the following steps: high pressure adsorption (HPA), first equalization drop (E1D)/second equalization drop (E2D)/purge pressurization (PP), depressurization (D)/purge (P), second equalization rise (E2R)/first equalization rise/waiting area, and final repressurization (FR). Then, the adsorption tower 1 enters a next closed-loop cycle operation process of adsorption and desorption. While the m-channel rotary valve continuously rotates during the closed-loop cycle operation process of adsorption and desorption in the adsorption tower 1, corresponding material gas and process gas entering and exiting the adsorption towers 2, 3, 4 and 5 are switched between entry and exit positions to perform the corresponding closed-loop cycle operation steps of adsorption and desorption. The closed-loop cycle operation steps of each of the 5 (n=5) adsorption towers correspond to the closed-loop cycle operation steps of each of the other 4 adsorption towers. As a result, an H.sub.2 product gas (H.sub.2PG) with a hydrogen (H.sub.2) concentration greater than or equal to 99.99% (v/v) is continuously produced from the GaN-MOCVD process exhaust gas as the feed gas, and the yield of the H.sub.2 product gas is 92-95%. As a result, energy consumption and emissions of desorbed gas can be significantly reduced, and high and low pressure (i.e., divided concentration relative to non-adsorbed hydrogen) adsorption in the GaN-MOCVD process exhaust gas, and both high purity and high yield in a simulated rotated PSA process on the basis of an axial flow fixed bed layer in the PSA process for extracting H.sub.2 and NH.sub.3 products from adsorbed phase gas and non-adsorbed phase gas. The obtained H.sub.2 and NH.sub.3 are then returned to the GaN-MOCVD process for recycling, thereby reusing the GaN-MOCVD process exhaust gas.
Example 2
[0026] As shown in FIG. 2, based on Example 1, the depressurization (D) step of the ammonia concentrate adsorbed phase is replaced with a vacuumizing (V) desorption step in the medium and high temperature PSA ammonia concentration system. Desorbed gas (D) formed by vacuumizing (V) flows out from an outlet end of an n (e.g., n=3) adsorption tower and flows through an external pipeline connected to an outlet end of the adsorption tower on the annular rotary tray. A vacuum pump and a control valve are arranged on the external pipeline to control a flow rate of the desorbed gas (D) before entering the ammonia-rich (concentrate) desorbed gas (NH.sub.3D) buffer tank, with a maximum vacuum degree of 0.08 MPa. Correspondingly, an original depressurization gas (D) channel (e.g., m=2) in the 6-channel rotary valve becomes an empty channel. Subsequently, ammonia-rich purge waste gas (NH.sub.3PW), generated when purge pressurization gas (PP) is used as purge gas (P) for purging (P), enters the empty channel, and is then mixed with ammonia-rich desorbed gas (NH.sub.3D) to form ammonia concentrated gas (NH.sub.3CG) which enters a condenser freezer through a heat exchanger 2 (cooler) to obtain a liquid ammonia product (NH.sub.3PL) with a purity greater than or equal to 99.995% and a yield greater than or equal to 99%. In addition, the purge pressurization gas (PP) used as the purge gas (P) also fills the vacuum in the adsorption tower, causing the n adsorption tower to return to normal pressure or slightly positive pressure, and also correspondingly alleviate the significant decrease in the ammonia content in non-adsorbed intermediate gas (IG) and non-condensable gas flowing out from a condenser freezer (refrigerator) as low pressure intermediate gas (LPIG), thereby greatly prolonging the service life of adsorbents in the intermediate gas PSA hydrogen purification system and the service life of adsorbents in the medium and high temperature PSA ammonia concentration system.
Example 3
[0027] As shown in FIG. 3, based on Examples 1 and 2, the depressurization (D) step of the ammonia concentrate adsorbed phase is replaced with a vacuumizing (V) desorption step in the intermediate gas PSA hydrogen purification system. Nitrogen-rich desorbed gas (N.sub.2D) formed by vacuumizing (V) flows out from the outlet end of an n (e.g., n=3) adsorption tower and flows through an external pipeline connected to the outlet end of the adsorption tower on the annular rotary tray. A vacuum pump and a control valve are arranged on the external pipeline to control the flow rate of the nitrogen-rich desorbed gas (N.sub.2D) before entering the nitrogen-rich desorbed gas (N.sub.2D) buffer tank, with a maximum vacuum degree of 0.08 MPa. Correspondingly, an original depressurization gas (D) channel (e.g., m=1) in the 7-channel rotary valve becomes an empty channel. Adsorbents in the n adsorption tower are completely desorbed, resulting in H.sub.2 product gas (H.sub.2PG) with a purity greater than or equal to 99.999% and a yield greater than or equal to 95%, thereby further prolonging the service life of the adsorbents.
[0028] Obviously, the above examples are only a part of the examples of the disclosure, but not all of them. Based on the examples recorded in the disclosure, all other examples obtained without creative work or structural changes made under the teaching of the disclosure by those skilled in the art, which have the same or similar technical solutions to those of the disclosure, fall within the protection scope of the disclosure.
