System for recovering and reducing hydrogen in tail gas

Abstract

The utility model relates to the technical field of hydrogen reduction systems, in particular to a system for recovering hydrogen in reduction tail gas, which comprises a reduction tank, a fuel gas pipe network, a reduction tail gas leading-out pipeline, a dechlorination tank and a reduction tail gas backflow pipeline, the reduction tank is connected with a reduction tail gas outlet pipeline; the fuel gas pipe network is connected with a reduction tail gas outlet pipeline, and a first stop valve is arranged on the fuel gas pipe network; the reduction tail gas leading-out pipeline is connected to a reduction tail gas outlet pipeline, the contact point of the reduction tail gas leading-out pipeline and the reduction tail gas outlet pipeline is located on the upstream of the first stop valve, and a one-way valve is arranged on the reduction tail gas leading-out pipeline; the dechlorination tank is connected with a reduction tail gas lead-out pipeline; and the reduction tail gas backflow pipeline is connected with the dechlorination tank and is connected to a circulating hydrogen feeding pipeline of the PSA system. The reduction tail gas is transferred to the PSA system, hydrogen in the reduction tail gas is recovered through pressure swing adsorption, and then the hydrogen yield is increased.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogen reduction systems, in particular to a system for recovering and reducing hydrogen in tail gas. Background Art

[0002] At present, the purification of hydrogen in the chemical production process usually adopts the PSA system, that is, the pressure swing adsorption system, which is a process for purifying gas mixtures. The process is based on the physical adsorption of gas molecules on the internal surface of porous solid materials (adsorbents). It is a reversible physical adsorption process that works between two pressure states. It is based on the principle that the impurity components in the mixed gas have a larger adsorption capacity under high pressure and a smaller adsorption capacity under low pressure, while the ideal component hydrogen has a smaller adsorption capacity regardless of high or low pressure. Under high pressure, the partial pressure of impurities is increased so that as much as possible can be adsorbed on the adsorbent, thereby achieving high product purity. The desorption or regeneration of the adsorbent is carried out at low pressure to minimize the residual amount of impurities on the adsorbent so that the impurities can be adsorbed again in the next cycle.

[0003] However, the reduction tail gas in the hydrogen reduction process is usually incorporated into the fuel gas pipeline network and used as heating furnace fuel. The hydrogen in it cannot be recycled, resulting in unnecessary waste. Utility Model Content

[0004] In view of the defects of the prior art, the utility model provides a system for recovering and reducing hydrogen in tail gas. In order to recover the hydrogen in the tail gas, the process is modified. The recovered tail gas continues to pass through PSA, that is, through a pressure swing adsorption system, to recover hydrogen, which can increase the hydrogen production.

[0005] In order to achieve the above-mentioned purpose, the technical solution provided by the utility model is a system for recovering hydrogen in reduction tail gas, which includes a reduction tank, a fuel gas pipeline network, a reduction tail gas outlet pipeline, a dechlorination tank and a reduction tail gas reflux pipeline; the reduction tank is connected to a reduction tail gas outlet pipeline; the fuel gas pipeline network is connected to the reduction tail gas outlet pipeline, and a first stop valve is provided on the fuel gas pipeline network; the reduction tail gas outlet pipeline is connected to the reduction tail gas outlet pipeline, and the meeting point between the reduction tail gas outlet pipeline and the reduction tail gas outlet pipeline is upstream of the first stop valve, and a one-way valve is provided on the reduction tail gas outlet pipeline; the dechlorination tank is connected to the reduction tail gas outlet pipeline; the reduction tail gas reflux pipeline is connected to the dechlorination tank, and the reduction tail gas reflux pipeline is connected to the circulating hydrogen feed pipeline of the PSA system.

[0006] Further, the PSA system includes a booster inlet pipeline connected to the circulating hydrogen feed pipeline, a booster connected to the booster inlet pipeline, a booster connected to the booster outlet pipeline, a first heat exchanger connected to the booster outlet pipeline, a second heat exchanger connected to the first heat exchanger, a re-contact tank connected to the second heat exchanger, and a PSA pressure swing adsorption tank connected to the first heat exchanger; the re-contact tank is respectively connected to the first heat exchanger and the second heat exchanger.

[0007] Furthermore, an air cooling fan is provided on the booster outlet pipeline.

[0008] Furthermore, the reduction tail gas reflux pipeline is connected to the supercharger inlet pipeline.

[0009] Furthermore, the PSA pressure swing adsorption tank is connected to a pure hydrogen delivery pipeline.

[0010] Furthermore, the pure hydrogen delivery pipeline is connected to the reduction tank.

[0011] Furthermore, a second stop valve is provided on the reduction tail gas outlet pipeline and upstream of the one-way valve.

[0012] Furthermore, the reduction tail gas reflux pipeline is provided with a third stop valve and a fourth stop valve.

[0013] Furthermore, the dechlorination tank is filled with a gas phase dechlorination agent.

[0014] The beneficial effects of the utility model are as follows: the hydrogen content in the reduction tail gas accounts for more than 90%, and the hydrogen is recovered through the PSA pressure swing adsorption system, that is, the reduction tail gas is transferred from the original fuel gas pipeline process to the PSA system for continued pressure swing adsorption, and the hydrogen in the reduction tail gas is recovered, thereby increasing the hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a process flow chart of a system for recovering and reducing hydrogen in tail gas in one embodiment of the utility model;

[0016] In the figure: 100, reduction tank, 110, reduction tail gas outlet pipeline,

[0017] 200, fuel gas pipeline network, 210, first stop valve,

[0018] 300, reduction tail gas outlet pipeline, 310, one-way valve, 320, second stop valve,

[0019] 400, dechlorination tank,

[0020] 500, reduction tail gas reflux pipeline, 510, third stop valve, 520, fourth stop valve,

[0021] 600, PSA system, 610, circulating hydrogen feed pipeline, 611, booster inlet liquid separator, 620, booster inlet pipeline, 630, booster, 640, booster outlet pipeline, 641, air cooling fan, 650, first heat exchanger, 660, second heat exchanger, 670, re-contact tank, 680, PSA pressure swing adsorption tank, 690, ammonia cooling system,

[0022] 700. Pure hydrogen delivery pipeline. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0024] See also Figure 1 , a system for recovering and reducing hydrogen in tail gas in one embodiment of the utility model, It includes a reduction tank 100, a fuel gas pipeline network 200, a reduction tail gas outlet pipeline 300, a dechlorination tank 400 and a reduction tail gas reflux pipeline 500; the reduction tank 100 is connected to a reduction tail gas outlet pipeline 110; the fuel gas pipeline network 200 is connected to the reduction tail gas outlet pipeline 300, and a first stop valve 210 is provided on the fuel gas pipeline network 200; the reduction tail gas outlet pipeline 300 is connected to the reduction tail gas outlet pipeline 110, and the meeting point between the reduction tail gas outlet pipeline 300 and the reduction tail gas outlet pipeline 110 is upstream of the first stop valve 210, and a one-way valve 310 is provided on the reduction tail gas outlet pipeline 300; the dechlorination tank 400 is connected to the reduction tail gas outlet pipeline 300; the reduction tail gas reflux pipeline 500 is connected to the dechlorination tank 400, and the reduction tail gas reflux pipeline 500 is connected to a circulating hydrogen feed pipeline 610 of a PSA system 600.

[0025] In order to recover the hydrogen in the reduction tail gas, the above-mentioned system for recovering hydrogen in the reduction tail gas is modified in process, and the recovered tail gas continues to pass through the PSA system, that is, through the pressure swing adsorption system, to recover hydrogen, which can increase the hydrogen production. In addition, in this embodiment, a first stop valve 210 is provided on the fuel gas pipeline network 200; the reduction tail gas lead-out pipeline 300 is connected to the reduction tail gas outlet pipeline 110, and the meeting point of the two is upstream of the first stop valve 210, so that the reduction tail gas can be switched between the process of going to the fuel gas pipeline network and the process of going to the PSA system as needed, thereby improving the flexibility of the system.

[0026] It should be noted that, in order to prevent the pressure from collided, a one-way valve 310 is added in the above embodiment. The reduction tail gas contains chloride ions, and a dechlorination tank 400 is added. The dechlorination tank 400 is filled with a gas phase dechlorinating agent, and regular sampling and analysis are performed. When the chlorine content at the outlet of the dechlorination tank 400 exceeds 0.5ppm, the dechlorinating agent in the tank needs to be replaced. In addition, the reduction tail gas outlet pipeline 300 is also a fuel gas pipeline. The fuel gas is flammable and explosive, and there is a high pressure channeling low pressure situation. Specifically, in one embodiment, a combustible gas alarm detector is set on the reduction tail gas outlet pipeline 300, and the position is included in the fuel gas inspection catalog. Such a setting improves the reliability and safety of the system.

[0027] In one embodiment, the PSA system 600 includes a booster inlet pipeline 620 connected to a circulating hydrogen feed pipeline 610, a booster 630 connected to the booster inlet pipeline 620, a booster outlet pipeline 640 connected to the booster 630, a first heat exchanger 650 connected to the booster outlet pipeline 640, a second heat exchanger 660 connected to the first heat exchanger 650, an ammonia cooling system 690 connected to the second heat exchanger 660, a re-contact tank 670 connected to the ammonia cooling system 690, and a PSA pressure swing adsorption tank 680 connected to the first heat exchanger 650; the re-contact tank 670 is respectively connected to the first heat exchanger 650 and the second heat exchanger 660. The circulating hydrogen feed pipeline 610 leads to a booster inlet liquid separator 611, and the booster inlet liquid separator 611 is connected to the booster inlet pipeline 620. The hydrogen enters the first heat exchanger 650 and the second heat exchanger 660 for heat exchange, and then enters the re-contact tank 670 after passing through the ammonia cooling system 690 .

[0028] It should be noted that the PSA system is a pressure swing adsorption system, which recovers or purifies hydrogen from a hydrogen-rich gas stream. By changing the operating conditions, hydrogen of different purities can be produced, and the purity of hydrogen can reach 99.99%. Pressure swing adsorption (PSA for short) is a new gas separation technology. Taking the adsorbent molecular sieve as an example, its principle is to separate the gas mixture by using the difference in the "adsorption" performance of the molecular sieve to different gas molecules. It uses air as the raw material and uses a high-efficiency, high-selectivity solid adsorbent to selectively adsorb nitrogen and oxygen to separate nitrogen and oxygen from the air. The separation effect of carbon molecular sieve on nitrogen and oxygen is mainly based on the different diffusion rates of the two gases on the surface of the carbon molecular sieve. The gas (oxygen) with a smaller diameter diffuses faster and enters more into the solid phase of the molecular sieve. In this way, the nitrogen enrichment component can be obtained in the gas phase. After a period of time, the molecular sieve reaches equilibrium in the adsorption of oxygen. According to the different characteristics of the carbon molecular sieve in the adsorption amount of the adsorbed gas under different pressures, the pressure is reduced to release the adsorption of oxygen by the carbon molecular sieve. This process is called regeneration.

[0029] In one embodiment, an air cooling fan 641 is provided on the booster outlet pipeline 640 .

[0030] In one embodiment, the reduced tail gas return pipeline 500 is connected to the booster inlet pipeline 620 .

[0031] In one embodiment, the PSA pressure swing adsorption tank 680 is connected to the pure hydrogen delivery pipeline 700 .

[0032] In one embodiment, the pure hydrogen delivery pipeline 700 is connected to the reduction tank 100 .

[0033] In one embodiment, a second stop valve 320 is disposed on the reduction tail gas outlet pipeline 300 and upstream of the one-way valve 310 .

[0034] In one embodiment, the reduction tail gas return pipeline 500 is provided with a third stop valve 510 and a fourth stop valve 520 .

[0035] In one embodiment, a gas phase dechlorinating agent is filled in the dechlorinating tank 400. During the production process, regular sampling and analysis are required. When the chlorine content at the outlet of the dechlorinating tank 400 exceeds 0.5 ppm, the dechlorinating agent in the tank needs to be replaced.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0038] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present utility model, unless otherwise clearly specified and limited, the first feature "above" or "below" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature may be that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

Claims

1. A system for recovering and reducing hydrogen from tail gas, characterized in that: include A reduction tank connected to a reduction tail gas outlet pipeline; A fuel gas pipeline network connected to the reduction tail gas outlet pipeline, wherein the fuel gas pipeline network is provided with a first stop valve; a reduction tail gas outlet pipeline connected to the reduction tail gas outlet pipeline, the meeting point of the reduction tail gas outlet pipeline and the reduction tail gas outlet pipeline being upstream of the first stop valve, and a one-way valve being arranged on the reduction tail gas outlet pipeline; a dechlorination tank connected to the reduction tail gas outlet pipeline; and The reduction tail gas reflux pipeline is connected to the dechlorination tank, and the reduction tail gas reflux pipeline is connected to the circulating hydrogen feed pipeline of the PSA system.

2. A system for recovering and reducing hydrogen in tail gas according to claim 1, characterized in that: The PSA system includes a booster inlet pipeline connected to the circulating hydrogen feed pipeline, a booster connected to the booster inlet pipeline, a booster connected to the booster outlet pipeline, a first heat exchanger connected to the booster outlet pipeline, a second heat exchanger connected to the first heat exchanger, a re-contact tank connected to the second heat exchanger, and a PSA pressure swing adsorption tank connected to the first heat exchanger; the re-contact tank is connected to the first heat exchanger and the second heat exchanger, respectively.

3. A system for recovering and reducing hydrogen in tail gas according to claim 2, characterized in that: An air cooling fan is arranged on the outlet pipeline of the booster.

4. A system for recovering and reducing hydrogen in tail gas according to claim 2, characterized in that: The reduced tail gas reflux pipeline is connected to the supercharger inlet pipeline.

5. A system for recovering and reducing hydrogen in tail gas according to claim 2, characterized in that: The PSA pressure swing adsorption tank is connected to a pure hydrogen delivery pipeline.

6. A system for recovering and reducing hydrogen in tail gas according to claim 5, characterized in that: The pure hydrogen delivery pipeline is connected to the reduction tank.

7. A system for recovering and reducing hydrogen in tail gas according to any one of claims 1 to 6, characterized in that: A second stop valve is arranged on the reduction tail gas outlet pipeline and upstream of the one-way valve.

8. A system for recovering and reducing hydrogen in tail gas according to any one of claims 1 to 6, characterized in that: The reduction tail gas reflux pipeline is provided with a third stop valve and a fourth stop valve.

9. A system for recovering and reducing hydrogen in tail gas according to any one of claims 1 to 6, characterized in that: The dechlorination tank is filled with a gas phase dechlorination agent.

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