Medium-temperature pressure swing adsorption separation device for hydrogen-doped hydrogen in natural gas pipeline network

Abstract

The utility model discloses a medium-temperature pressure swing adsorption separation device for hydrogen-doped hydrogen in a natural gas pipeline network. The medium-temperature pressure swing adsorption separation device comprises a plurality of adsorption towers which are arranged in parallel, hydrogen storage alloy adsorbents are filled in the towers, the bottoms of the adsorption towers are connected with a hydrogen-doped natural gas inlet pipeline and a hydrogen outlet pipeline, and the tops of the adsorption towers are connected with a pressure equalizing pipeline and a concurrent discharge amp; a replacement pipeline, a final charging pipeline and a natural gas outlet pipeline; the hydrogen outlet pipeline is connected with a hydrogen buffer tank through a vacuum pump; one or more pressure-equalizing pipelines are arranged according to the requirement of pressure-equalizing times, and each pressure-equalizing pipeline is connected with one pressure-equalizing buffer tank. The temperature of the adsorption towers is controlled to be 60-120 DEG C, all the adsorption towers circularly operate for adsorption, pressure drop is equalized, and amp is smoothly discharged; the method comprises the steps of adsorption, replacement, vacuum-pumping desorption, pressure rise equalization and final charging, all adsorption towers cooperate through sequential control and enter the adsorption step in turn, efficient and rapid separation of hydrogen and natural gas is achieved, the purity of hydrogen can reach 99.999%, the yield can reach 80% or above, and the hydrogen can be directly applied to a hydrogen refueling station or a hydrogen storage device and the like.

Description

Technical Field

[0001] The utility model belongs to the technical field of industrial gas separation, relates to a direct separation technology of hydrogen mixed with hydrogen in a natural gas pipeline network, and specifically relates to a medium-temperature pressure swing adsorption separation device based on a hydrogen storage alloy adsorbent. Background Art

[0002] The hydrogen blending technology in natural gas pipelines can not only reduce the carbon emission intensity during the use of natural gas, but also solve the problem of absorbing large-scale renewable energy, and is expected to achieve large-scale, long-distance and low-cost transportation and storage of hydrogen. At present, the concentration of hydrogen blending in natural gas pipelines is about 3%-20%, and the hydrogen concentration and hydrogen partial pressure are relatively low. Hydrogen can be directly separated by membrane separation technology, electrochemical separation, cryogenic separation, pressure swing adsorption and hydrogen storage alloy separation. The pressure swing adsorption method and hydrogen storage alloy separation method are mainly analyzed.

[0003] Pressure swing adsorption utilizes the differences in the adsorption characteristics of gas components on adsorbents and the characteristics of the adsorption amount changing with pressure. It uses high-pressure adsorption and low-pressure desorption. The opening and closing of programmable valves can achieve periodic changes in the pressure of the adsorption tower to separate and purify the gas. It is widely used in the field of gas separation and purification. It has the advantages of short separation cycle, large-scale, long cycle life, low energy consumption, and mature technology. However, the separation coefficient of methane and hydrogen is low on most industrial adsorbents, and the methane adsorption amount is much greater than that of hydrogen. In the application of hydrogen purification of natural gas, if methane is used as the adsorption phase for hydrogen purification, the equipment volume will be too large, the investment will be too high, and the purity and yield of hydrogen will be difficult to guarantee. On the other hand, it will cause methane pressure loss and increased loss. Hydrogen storage alloys can catalytically dissociate hydrogen into hydrogen atoms and store them in metal lattices, and realize the reversible absorption and release of hydrogen through changes in pressure and temperature. It has a wide range of application scenarios in the field of hydrogen storage and separation and purification. Hydrogen storage alloys are used as adsorbents in the pressure swing adsorption process to directly separate hydrogen from hydrogen-doped natural gas. The advantages of hydrogen storage alloys in efficiently adsorbing hydrogen and the advantages of the pressure swing adsorption process, which is efficient, mature and low-cost, are effectively utilized. The medium-temperature process is used to improve the kinetic efficiency of hydrogen adsorption and desorption, and high-purity, high-yield and large-scale separation of hydrogen can be achieved. Utility Model Content

[0004] The purpose of the utility model is to propose a device for directly separating hydrogen in a natural gas pipeline network hydrogen blending scenario based on a hydrogen storage alloy adsorbent and a medium-temperature multi-tower pressure swing adsorption process, so as to achieve high-purity and high-yield separation of hydrogen.

[0005] In order to achieve the above technical purpose, the utility model adopts the following technical solutions:

[0006] A medium-temperature pressure swing adsorption separation device for hydrogen-doped hydrogen in a natural gas pipeline network comprises a plurality of adsorption towers arranged in parallel, as well as a natural gas inlet pipeline, a hydrogen outlet pipeline, a pressure equalizing pipeline, a discharge & replacement pipeline, a final charging pipeline and a natural gas outlet pipeline; a hydrogen storage alloy adsorbent is filled in the adsorption tower; the bottom of each adsorption tower is connected to a hydrogen-doped natural gas inlet pipeline and a hydrogen outlet pipeline, and the top of each adsorption tower is connected to a pressure equalizing pipeline, a discharge & replacement pipeline, a final charging pipeline and a natural gas outlet pipeline, and a program-controlled valve is arranged between each adsorption tower and each pipeline; the hydrogen outlet pipeline is connected to a hydrogen buffer tank through a vacuum pump; one or more pressure equalizing pipelines are arranged according to the pressure equalizing times, and each pressure equalizing pipeline is connected to a pressure equalizing buffer tank; a discharge program-controlled valve and a discharge back-pressure valve are arranged at the outlet of the discharge & replacement pipeline; a natural gas back-pressure valve is arranged at the outlet of the natural gas outlet pipeline; the other end of the natural gas outlet pipeline is connected to the final charging pipeline, and a final charging program-controlled valve and a final charging regulating valve are arranged at the connection between the two.

[0007] The medium-temperature pressure swing adsorption separation device for hydrogen-doped natural gas pipelines is used to control the temperature of the adsorption tower at 60°C-120°C, and each adsorption tower periodically operates the following steps:

[0008] 1) Adsorption step: hydrogen-blended natural gas (usually a high-pressure pipeline with a pressure of 16-40 bar) enters from the bottom of the adsorption tower, hydrogen is adsorbed by the hydrogen storage alloy adsorbent, and the unadsorbed natural gas is discharged from the top of the tower for recycling and continued use downstream, achieving direct separation of hydrogen and natural gas. When the instantaneous concentration of hydrogen in the discharged natural gas reaches 0.5%-1%, the adsorption is stopped;

[0009] 2) Pressure reduction step: The pressure in the adsorption tower is gradually reduced by equalizing the pressure with other adsorption towers or pressure equalizing buffer tanks at a lower pressure. The pressure equalizing gas is discharged from the top of the tower. The pressure difference of a single pressure reduction is controlled within the range of 3-5 bar. At the end of the pressure equalization, most of the natural gas pressure is recovered to the adsorption tower or pressure equalizing buffer tank at a lower pressure, which greatly reduces the loss of natural gas.

[0010] 3) Downstream discharge & replacement step: further reduce the pressure in the adsorption tower to reduce the natural gas content during hydrogen desorption, control the downstream discharge pressure at 0-0.5 bar, and discharge the residual natural gas in the tower. At the same time, driven by the pressure difference and temperature, the unstable adsorbed hydrogen is desorbed from the hydrogen storage alloy adsorbent to replace the flushing natural gas, further reducing the residual natural gas content in the tower. The amount of spontaneous hydrogen desorption is controlled by controlling the pressure and time during the downstream discharge & replacement process and the temperature of the adsorption tower;

[0011] 4) Vacuum desorption step: The hydrogen is rapidly desorbed from the hydrogen storage alloy adsorbent by vacuuming. When the pressure in the tower drops to close to -1 bar, it means that most of the hydrogen is desorbed, and the hydrogen storage alloy adsorbent is regenerated, and the pressure can be increased for the next round of adsorption;

[0012] 5) Pressure equalization step: gradually increase the pressure in the adsorption tower by equalizing the pressure with other adsorption towers or pressure equalization buffer tanks in a higher pressure state, and the pressure equalization gas enters the adsorption tower from the top of the tower. The pressure difference of a single pressure increase is controlled within the range of 3-5 bar;

[0013] 6) Final charging step: When the pressure has not reached the adsorption pressure at the end of the equalization pressure rise, the high-pressure natural gas discharged from other adsorption towers is introduced into the adsorption tower as the final charging gas to increase the pressure inside the tower to the adsorption pressure, and then the next cycle can be carried out;

[0014] Each adsorption tower runs the above steps periodically. At the same time point, each adsorption tower is in a different step. Through timing control, the adsorption towers cooperate with each other and enter the adsorption step in turn to jointly complete the efficient recovery of hydrogen in hydrogen-blended natural gas.

[0015] In some embodiments of the utility model, six adsorption towers are arranged in parallel. Furthermore, two equalizing pressure pipelines and two equalizing pressure buffer tanks are arranged, wherein the first equalizing pressure pipeline is connected to the first equalizing pressure buffer tank, the second equalizing pressure pipeline is connected to the second equalizing pressure buffer tank, and program-controlled valves are arranged at the entrances of the first equalizing pressure buffer tank and the second equalizing pressure buffer tank, respectively. At each moment, only one adsorption tower is in the adsorption step, and the six adsorption towers enter the adsorption step in turn; in the equalizing pressure drop step, five equalizing pressures are carried out to gradually reduce the pressure, and in the equalizing pressure increase step, five equalizing pressures are also carried out to gradually increase the pressure.

[0016] It should be noted that:

[0017] 1. Hydrogen-blended natural gas needs to be pretreated before entering the pressure swing adsorption device to remove impurities such as CO, sulfide and O2. These substances can easily cause the hydrogen storage alloy adsorbent to be deactivated and difficult to recover. Carbon-containing polycarbons have a large molecular weight and will not be adsorbed on the adsorbent and can be discharged with the airflow.

[0018] 2. The hydrogen storage alloy adsorbent is prepared by granulating and molding hydrogen storage alloy powder and additives. The selection conditions of hydrogen storage alloy powder are that it has excellent hydrogen absorption and desorption kinetics and low hydrogen absorption platform pressure, can absorb hydrogen at room temperature, and can tolerate methane. AB2 and AB5 type alloys are preferred. Additives include inorganic binders, inorganic anti-expansion agents and metal thermal conductors. The additives are all inorganic materials or metal materials, because inorganic materials are resistant to high temperatures and have stable structures, and will not react with hydrogen storage alloy powder and gas.

[0019] 3. In order to improve the purity of hydrogen while ensuring the yield of hydrogen, the residual natural gas in the bed must be reduced as much as possible during the discharge and replacement steps. Therefore, the hydrogen is quickly desorbed from the easily desorbed parts during the discharge process to replace and flush the bed.

[0020] 4. In order to ensure a high recovery rate of natural gas, the number of pressure equalization times must be increased as much as possible to reduce the loss of natural gas in the sequential release steps and improve the economy of the device.

[0021] Compared with the existing technology, it has the following advantages:

[0022] 1. The hydrogen storage alloy adsorbent is combined with the medium-temperature pressure swing adsorption process. The hydrogen separation efficiency is high and the separation gas volume is large, which can realize large-scale continuous production. The process is mature, low cost and low energy consumption.

[0023] 2. The purity of the separated hydrogen can reach 99.999%, and the yield can reach more than 80%, which can be directly used by hydrogen refueling stations and hydrogen storage devices. If the hydrogen purity requirement is reduced to 95%, the hydrogen yield can reach more than 95%.

[0024] 3. Hydrogen is used as the adsorption phase and natural gas is used as the non-adsorption phase. The entire separation process has almost no effect on the pressure of natural gas. More than 95% of the natural gas is recovered, and only a small amount of natural gas is lost during the discharge process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The utility model is a schematic diagram of the principle of directly separating hydrogen mixed in a natural gas pipeline network through a medium-temperature pressure swing adsorption process.

[0026] Figure 2 Schematic diagram of the structure of the medium-temperature pressure swing adsorption device described in the embodiment, wherein: 1 is a hydrogen-blended natural gas inlet pipeline, 101-106 are program-controlled valves corresponding to each adsorption tower on the hydrogen-blended natural gas inlet pipeline 1; 2 is a hydrogen outlet pipeline, 201-206 are program-controlled valves on the hydrogen outlet pipeline 2 of each adsorption tower; 3 is a first equalizing pressure pipeline, 301-306 are program-controlled valves corresponding to each adsorption tower on the first equalizing pressure pipeline; 4 is a second equalizing pressure pipeline, 401-406 are program-controlled valves corresponding to each adsorption tower on the second equalizing pressure pipeline 2; 5 is a sequential release & replacement pipeline, 501-506 are program-controlled valves corresponding to each adsorption tower on the sequential release & replacement pipeline 5 corresponding program-controlled valves; 6 is the final charging pipeline, 601-606 are the program-controlled valves corresponding to the final charging pipeline 6 on each adsorption tower; 7 is the natural gas outlet pipeline, 701-706 are the program-controlled valves corresponding to the natural gas outlet pipeline 7 on each adsorption tower; 8 is a vacuum pump; 9 is a hydrogen buffer tank; 10 is the first pressure equalizing buffer tank; 11 is the second pressure equalizing buffer tank; 12 is a natural gas back-pressure valve; 13 is a downstream back-pressure valve; 14 is a final charging regulating valve; 15 is a final charging program-controlled valve; 16 is the first pressure equalizing buffer tank program-controlled valve, 17 is the second pressure equalizing buffer tank program-controlled valve; 18 is a downstream regulating valve; T01-T06 represent each adsorption tower, and are equipped with a heating device.

[0027] Figure 3 Schematic diagram of the change of the pressure in the adsorption tower with the steps and time sequence in the embodiment. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below with reference to the accompanying drawings. The described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0029] The technical solution of the utility model is described in detail below through embodiments.

[0030] In this embodiment, the pipeline pressure of hydrogen-doped natural gas during hydrogen separation is high-pressure B-grade 16bar, and the hydrogen concentration is 3-20% as a reference, that is, the adsorption pressure is 16bar, the pressure during hydrogen desorption is ≈-1bar, and the total pressure difference experienced by the adsorption tower is 17bar. According to the experience requirements of the pressure swing adsorption process, the adsorption tower is reduced from the high-pressure adsorption state to the low-pressure desorption state or from the low-pressure desorption state to the high-pressure adsorption state. Each pressure change should be controlled at 3-5bar, that is, at least 4-5 pressure change steps of pressure drop or pressure increase are required. According to the pressure swing adsorption process design requirements such as the pressure equalization number requirements, timing arrangement, pipeline design, etc., a 6-1-5 operation sequence is selected, where 6 represents that the device has a total of 6 circulating adsorption towers, 1 represents that 1 tower is in the adsorption state at any time, and 5 represents 5 pressure equalizations. The timing table is shown in Table 1. Each tower cycle undergoes six steps: adsorption, pressure drop 5 times, sequential release & replacement, vacuum desorption, pressure increase 5 times, and final filling. In the timing table, a total of 24 time sequences are divided. According to the requirements of the operation schedule, the required device diagram is as follows Figure 2As shown, it includes 6 parallel adsorption towers T01-T06, 2 equalizing buffer tanks, 1 hydrogen buffer tank, 1 vacuum pump and several program-controlled valves, back pressure valves, regulating valves and pipelines, etc., wherein the bottom of each adsorption tower is connected to a hydrogen-blended natural gas inlet pipeline 1 and a hydrogen outlet pipeline 2, and the top of the tower is connected to a first equalizing pressure pipeline 3, a second equalizing pressure pipeline 4, a downstream & replacement pipeline 5, a final filling pipeline 6 and a natural gas outlet pipeline 7, and a program-controlled valve is arranged between each adsorption tower and each pipeline, and the connection state is controlled by opening and closing the program-controlled valve; the hydrogen outlet pipeline The first pressure equalizing pipeline 3 is connected to the first pressure equalizing buffer tank 10, and a program-controlled valve 16 is set; the second pressure equalizing pipeline 4 is connected to the second pressure equalizing buffer tank 11, and a program-controlled valve 17 is set; the outlet of the said downstream & replacement pipeline 5 is provided with a downstream program-controlled valve 18 and a downstream back pressure valve 13; the outlet of the natural gas outlet pipeline 7 is provided with a natural gas back pressure valve 12; the other end of the natural gas outlet pipeline 7 is connected to the said final filling pipeline 6, and a final filling program-controlled valve 15 and a final filling regulating valve 14 are set at the connection between the two. The pressure in the adsorption tower is adjusted by switching the program-controlled valve on and off, thereby realizing the conversion of the steps such as adsorption, pressure equalization and desorption.

[0031] Table 1 Runtime table

[0032]

[0033] Note: A is an adsorption step, ED1 is a one-way pressure drop step, ED2 is a two-way pressure drop step, ED3 is a three-way pressure drop step, ED4 is a four-way pressure drop step, ED5 is a five-way pressure drop step, PP is a sequential release & replacement step, V is a vacuum desorption step, ER5 is a five-way pressure increase step, ER4 is a four-way pressure increase step, ER3 is a three-way pressure increase step, ER2 is a two-way pressure increase step, ER1 is a one-way pressure increase step, and FR is a final charging step.

[0034] Taking adsorption tower T01 as an example, combined with Table 1, Figure 2 and Figure 3 The operation cycle of the adsorption tower is explained.

[0035] 1. Adsorption step (sequence #1-#4): Figure 2 As shown, the program-controlled valve 101 and the program-controlled valve 701 of the adsorption tower T01 are opened, and the hydrogen-blended natural gas enters the adsorption tower from the program-controlled valve 101 on the hydrogen-blended natural gas inlet pipeline 1. The hydrogen, as a strong adsorption component, is adsorbed by the hydrogen storage alloy adsorbent filled in the adsorption tower, and the unadsorbed natural gas enters the natural gas outlet pipeline 7 through the program-controlled valve 701. Figure 3 As shown in the figure, the pressure in the adsorption tower T01 is maintained at P during the entire adsorption process. 吸附 state, the natural gas outlet pressure is also P 吸附 Continue to transmit to the user end for use.

[0036] 2. Pressure reduction step (sequence #5 to #9): After the adsorption step, the adsorption tower T01 needs to be gradually reduced from the high pressure state of the adsorption state to the low pressure state to desorb the hydrogen. This is done in 5 steps. Sequence #5 is a pressure reduction step. The program-controlled valves 301 and 303 are opened. The pressure-equalizing gas of the adsorption tower T01 enters the adsorption tower T03 through the program-controlled valves 301 and 303. The pressure in the adsorption tower T01 is reduced by P 吸附 →P 均压降1 Sequence #6 is the second pressure drop step. The program-controlled valve 301 and the program-controlled valve 16 of the first pressure-equalizing buffer tank are opened. The pressure-equalizing gas generated by the adsorption tower T01 is discharged from the program-controlled valve 301 into the first pressure-equalizing buffer tank 10. The pressure in the adsorption tower T01 decreases by P 均压降1 →P 均压降2 Sequence #7 is the three-level pressure drop step. The program-controlled valves 301 and 304 are opened, and the pressure-equalizing gas generated by the adsorption tower T01 enters the adsorption tower T04 through the program-controlled valves 301 and 304. The pressure in the adsorption tower T01 is further reduced. 均压降2 →P 均压降3 Sequence #8 is the fourth pressure drop step. The program-controlled valve 401 and the program-controlled valve 17 of the second pressure-equalizing buffer tank are opened. The pressure-equalizing gas generated by the adsorption tower T01 enters the second pressure-equalizing buffer tank 11 through the program-controlled valve 401 and the program-controlled valve 17 of the second pressure-equalizing buffer tank. The pressure in the adsorption tower T01 decreases by P 均压降3 →P 均压升4 Sequence #9 is the fifth pressure drop step. The program-controlled valves 401 and 405 are opened. The pressure-equalizing gas generated by the adsorption tower T01 enters the adsorption tower T05 through the program-controlled valves 401 and 405. The pressure in the adsorption tower T01 decreases by P 均压降4 →P 均压降5 .

[0037] like Figure 3 As shown, the pressure in adsorption tower T01 changes from P 吸附 →P 均压降1 →P 均压降2 →P 均压降3 →P 均压降4 →P 均压降5 The pressure is reduced step by step, and the main component of the pressure-equalizing gas discharged during the pressure reduction process is natural gas, which is recycled for the pressure-increasing steps of other towers. This process greatly improves the recovery rate of natural gas. The more times the pressure is equalized, the more natural gas and pressure are recovered. Among them, the adsorption tower T01 completes the pressure-equalizing step by switching the program-controlled valves on the first pressure-equalizing pipeline 3 and the second pressure-equalizing pipeline 4. The first pressure-equalizing step, the second pressure-equalizing step and the third pressure-equalizing step are performed on the first pressure-equalizing pipeline 3, and the fourth pressure-equalizing step and the fifth pressure-equalizing step are performed on the second pressure-equalizing pipeline 4.

[0038] 3. Sequential placement & replacement steps (sequence #10 to #12): After the pressure drop is completed, the pressure in adsorption tower T01 is P 均压降5> Normal pressure, the residual natural gas in the adsorption tower must be eliminated to avoid affecting the purity of hydrogen, the programmable valve 501 is opened, the downstream regulating valve 18 adjusts the downstream gas discharge rate, and the downstream back pressure valve 13 is controlled at near normal pressure. The residual natural gas in the tower is discharged from the adsorption tower T01 through the programmable valve 501, the downstream regulating valve 18, and the downstream back pressure valve 13 along with the pressure difference. The pressure in the adsorption tower T01 drops to normal pressure. At this time, the partial pressure of hydrogen is also greatly reduced. The hydrogen that is not stably adsorbed is spontaneously desorbed under the induction of the pressure difference, and the residual natural gas in the bed is flushed and replaced to further improve the purity of hydrogen. The removal rate of natural gas in the adsorption tower is the key factor determining the purity of hydrogen. The removal rate of natural gas and the purity of hydrogen are improved by pressure difference control, temperature control, and downstream gas discharge rate control.

[0039] 4. Vacuum desorption step (sequence #13 to #16): The desorption of hydrogen by the hydrogen storage alloy adsorbent is an endothermic reaction with slow reaction kinetics. In order to meet the requirements of the pressure swing adsorption process for rapid desorption of hydrogen and increase the desorption amount and yield of hydrogen, a vacuum pump is set to increase the rate of hydrogen desorption. The program-controlled valve 201 is opened, and under the action of the vacuum pump 8, the hydrogen is rapidly desorbed and enters and is stored in the hydrogen buffer tank 9 through the program-controlled valve 201 and the vacuum pump 8. The purity of the desorbed hydrogen reaches 99%-99.9999%, and the pressure P in the adsorption tower T01 is 1.5-2.0. 真空解吸 When the pressure drops to close to -1 bar, it means that almost all the hydrogen adsorbed by the hydrogen storage alloy adsorbent has been desorbed, that is, the alloy adsorbent has been regenerated and the pressure can be increased to enter the next adsorption cycle.

[0040] 5. Pressure-equalizing step (sequence #17 to #21): After the hydrogen desorption step, the adsorption tower T01 needs to be gradually upgraded from the low-pressure desorption state to the high-pressure state to prepare for the next adsorption cycle. There are 5 steps in total, namely, the fifth pressure-equalizing step, the fourth pressure-equalizing step, the third pressure-equalizing step, the second pressure-equalizing step and the first pressure-equalizing step, which correspond to the sequence #17-#21 respectively. Sequence #17 is the fifth pressure-equalizing step. The program-controlled valves 401 and 403 are opened. The pressure-equalizing gas from the adsorption tower T03 enters the adsorption tower T01 through the program-controlled valves 403 and 401. The pressure in the adsorption tower T01 increases by P 真空解吸 →P 均压升5 Sequence #18 is the fourth pressure-equalizing step. The program-controlled valve 401 and the program-controlled valve 17 of the second pressure-equalizing buffer tank are opened. The pressure-equalizing gas from the second pressure-equalizing buffer tank 11 enters the adsorption tower T01 through the program-controlled valve 401. The pressure in the adsorption tower T01 increases by P 均压升5 →P 均压升4 Sequence #19 is the three-step pressure increase. The program-controlled valves 301 and 304 are opened. The pressure-equalizing gas from the adsorption tower T04 enters the adsorption tower T01 through the program-controlled valves 304 and 301. The pressure in the adsorption tower T01 increases by P 均压升4 →P 均压升3Sequence #20 is the second pressure-equalizing step. The program-controlled valve 301 and the program-controlled valve 16 of the first pressure-equalizing buffer tank are opened. The pressure-equalizing gas from the first pressure-equalizing buffer tank 10 enters the adsorption tower T01 through the program-controlled valve 301. The pressure in the adsorption tower T01 increases by P 均压升3 →P 均压升2 Sequence #21 is a pressure-equalizing step. The program-controlled valves 301 and 305 are opened. The pressure-equalizing gas from the adsorption tower T05 enters the adsorption tower T01 through the program-controlled valves 305 and 301. The pressure in the adsorption tower T01 increases by P 均压升2 →P 均压升1 .

[0041] like Figure 3 As shown, the pressure in adsorption tower T01 changes from P 真空解吸 →P 均压升5 →P 均压升4 →P 均压升3 →P 均压升2 →P 均压升1 The pressure increases step by step, wherein the adsorption tower T01 completes the pressure increasing step by switching the programmable valves on the second pressure equalizing pipeline 4 and the first pressure equalizing pipeline 3, the five pressure increasing steps and the four pressure increasing steps are carried out on the second pressure equalizing pipeline 4, and the three pressure increasing steps, the two pressure increasing steps and the one pressure increasing step are carried out on the first pressure equalizing pipeline 3.

[0042] 6. Final filling step (sequence #22 to #24): When the pressure in adsorption tower T01 rises to P 均压升1 After that, P 吸附 The pressure can no longer be increased by equalizing the pressure with other adsorption towers or equalizing buffer tanks. The high-pressure natural gas in the natural gas outlet pipeline 7 is used to slowly increase the pressure of the adsorption tower T01, that is, the pressure of the adsorption tower T01 can be increased to P without affecting the adsorption process of the adsorption tower in the adsorption state. 吸附 This process corresponds to the timing #22-#24, the program-controlled valve 601 and the final filling program-controlled valve 15 are opened, and the final filling regulating valve 14 is used to adjust the final filling rate. At this time, the adsorption tower T06 is in the adsorption step, and part of the natural gas discharged from it enters the adsorption tower T01 through the program-controlled valves 606 and 601, the final filling program-controlled valve 15 and the final filling regulating valve 14 until the pressure reaches P 吸附 .

[0043] The above describes the operation cycle of an adsorption tower by taking adsorption tower T01 as an example. Other adsorption towers are operated simultaneously according to the timing chart shown in Table 1 to achieve continuous adsorption, pressure equalization and desorption of hydrogen in hydrogen-blended natural gas to obtain high-purity hydrogen.

[0044] Based on hydrogen storage alloy adsorbents and optimization of the medium-temperature pressure swing adsorption process, the ultimate goal is to achieve a hydrogen purity of more than 99.999% and a yield of more than 80%. It can be used in hydrogen refueling stations, fuel cell vehicles, etc., and has no impact on the subsequent application of natural gas.

[0045] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solution of the present invention, but not to limit it, and certainly not to limit the protection scope of the present invention. Any non-creative changes or modifications made to the main design concept and spirit of the present invention, which solve technical problems consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solution of the present invention in other related technical fields is also included in the protection scope of the present invention.

Claims

1. A medium-temperature pressure swing adsorption separation device for hydrogen-doped natural gas pipeline network, characterized in that: It comprises a plurality of adsorption towers arranged in parallel, as well as a natural gas inlet pipeline, a hydrogen outlet pipeline, a pressure equalizing pipeline, a discharge & replacement pipeline, a final charging pipeline and a natural gas outlet pipeline; the adsorption tower is filled with a hydrogen storage alloy adsorbent; the bottom of each adsorption tower is connected to a hydrogen-blended natural gas inlet pipeline and a hydrogen outlet pipeline, and the top of each adsorption tower is connected to a pressure equalizing pipeline, a discharge & replacement pipeline, a final charging pipeline and a natural gas outlet pipeline, and a program-controlled valve is arranged between each adsorption tower and each pipeline; the hydrogen outlet pipeline is connected to a hydrogen buffer tank through a vacuum pump; one or more pressure equalizing pipelines are arranged according to the number of pressure equalization times, and each pressure equalizing pipeline is connected to a pressure equalizing buffer tank; a discharge program-controlled valve and a discharge back-pressure valve are arranged at the outlet of the discharge & replacement pipeline; a natural gas back-pressure valve is arranged at the outlet of the natural gas outlet pipeline; the other end of the natural gas outlet pipeline is connected to the final charging pipeline, and a final charging program-controlled valve and a final charging regulating valve are arranged at the connection between the two.

2. The device according to claim 1, characterized in that There are 6 adsorption towers.

3. The device according to claim 2, characterized in that The pressure equalizing pipeline includes a first pressure equalizing pipeline and a second pressure equalizing pipeline, wherein the first pressure equalizing pipeline is connected to a first pressure equalizing buffer tank, and the second pressure equalizing pipeline is connected to a second pressure equalizing buffer tank, and programmable valves are respectively arranged at the inlets of the first pressure equalizing buffer tank and the second pressure equalizing buffer tank.

4. The device according to claim 1, characterized in that The hydrogen storage alloy adsorbent is an AB2 or AB5 type alloy.

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