Pressure swing adsorption desorption gas recovery system

Abstract

The utility model discloses a kind of pressure swing adsorption desorption gas recovery systems, technical scheme is as follows: including ammonia's PSA device, the desorption gas generated by PSA device is divided into two ways by desorption gas pipe, one way is sent to purification conversion preheating furnace by conversion pipe, another way is vented to flare combustion by vent pipe, the conversion pipe is mixed with the TSA regeneration gas of purification synthetic section by bypass's mixing pipe, the gas after mixing is sent to coking furnace using by back furnace gas pipeline, a kind of pressure swing adsorption desorption gas recovery system provided in the present application is sent to coking furnace using by mixing desorption gas with TSA regeneration gas, while optimizing adsorption tower structure and strengthening pipeline control, effectively solve the problem that desorption gas utilization rate is low in prior art, adsorption efficiency is poor and pipeline safety hidden danger, with the advantages of improving energy recovery rate, enhancing separation effect and guaranteeing system safe operation.

Description

Technical Field

[0001] This utility model relates to the field of pressure swing adsorption, and specifically to a pressure swing adsorption desorption gas recovery system. Background Technology

[0002] In the ammonia production project, when the ammonia division workshop uses the PAS (Pressure Swing Adsorption) process for normal production, the adsorption towers of the two A / B series full-load PSA units generate a large amount of desorbed gas, with a flow rate as high as 18262 Nm3 / H (mainly composed of hydrogen and nitrogen). In existing technology, this desorbed gas is simply divided into two paths: one is sent to the A / B series conversion preheater in the purification workshop for utilization, and the other is directly discharged to the flare for combustion through the vent pipeline. Meanwhile, although the regenerated coke oven gas produced by the TSA system in the ammonia purification synthesis section is sent to the coking furnace for reuse, a considerable portion of the desorbed gas generated by PAS is wasted through flare combustion. This treatment method not only results in the loss of a large amount of recoverable energy but also increases the risk of environmental pollution. The existing system suffers from uneven adsorbent distribution in the adsorption tower structure design, leading to low separation efficiency; and lacks precise flow regulation and safety protection mechanisms in pipeline control, failing to maximize the utilization of the desorbed gas. In particular, the lack of effective pressure balancing and component control measures during gas mixing in different process stages restricts the improvement of the overall system's energy efficiency. Utility Model Content

[0003] To address the aforementioned problems, this invention provides a pressure swing adsorption desorption gas recovery system.

[0004] This utility model is achieved through the following technical solution:

[0005] This application provides a pressure swing adsorption (PSA) desorption gas recovery system, the technical solution of which is as follows: including an ammonia PSA unit, the desorption gas generated by the PSA unit is divided into two paths through the desorption gas pipeline, one path is sent to the purification conversion preheating furnace through the conversion pipe, and the other path is vented to the flare for combustion through the vent pipe. The conversion pipe is mixed with the TSA regeneration gas of the purification synthesis section through the bypass mixing pipe, and the mixed gas is sent to the coking furnace for use through the return gas pipeline.

[0006] Furthermore, this application also proposes that the adsorption tower of the PSA device adopts a stacked non-uniformly packed adsorption tower structure to achieve a gradient distribution of adsorbent particle size and porosity.

[0007] Furthermore, this application also proposes that the mixing pipe is equipped with a control valve and a check valve.

[0008] Furthermore, this application also proposes that a normally closed control valve be installed on the vent pipe.

[0009] Compared with existing technologies, the beneficial effects of this utility model are as follows: The pressure swing adsorption desorption gas recovery system provided in this application mixes the desorption gas with TSA regeneration gas and sends it to the coking furnace for use. At the same time, it optimizes the adsorption tower structure and strengthens pipeline control, effectively solving the problems of low desorption gas utilization, poor adsorption efficiency and pipeline safety hazards in the existing technology. It has the advantages of improving energy recovery rate, enhancing separation effect and ensuring safe operation of the system. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the system of this utility model;

[0011] In the diagram: 1. PSA unit, 2. Adsorption tower, 3. Desorption gas pipe, 4. Conversion pipe, 5. Conversion preheater, 6. Mixing pipe, 7. Top cover, 8. TSA synthesis unit, 9. Control valve, 10. Return gas pipeline, 11. Vent pipe. Detailed Implementation

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0013] like Figure 1 As shown, this application proposes a pressure swing adsorption (PSA) desorbed gas recovery system, including an ammonia PSA unit. The desorbed gas generated by the PSA unit is split into two paths through the desorbed gas pipeline. One path is sent to the purification conversion preheater through the conversion pipeline, and the other path is vented to the flare for combustion through the vent pipeline. The conversion pipeline is mixed with the TSA regenerated gas from the purification synthesis section through the bypass mixing pipeline. The mixed gas is sent to the coking furnace for use through the return gas pipeline.

[0014] The PSA unit uses pressure swing adsorption (PSA) technology to separate specific components from a gas mixture. The desorbed gas line transports the gas released during desorption. The conversion line delivers the desorbed gas to a purification conversion preheater for further processing, and the vent line discharges excess gas to a flare for combustion. The mixing line mixes the desorbed gas with TSA regenerated gas, which originates from the temperature swing adsorption regeneration process in the purification synthesis section. The return gas line delivers the mixed gas to the coking oven for use as fuel. Control valves regulate gas flow, and check valves prevent backflow.

[0015] This technical solution effectively reduces the amount of gas directly emitted into the flare for combustion by mixing PSA desorbed gas and TSA regenerated gas and then recycling them back into the coking oven. The mixing pipe design enables the comprehensive utilization of both waste gases, with the recycled gas pipeline recovering the mixed gas as fuel. Compared to existing technologies, this system improves waste gas utilization, reduces energy waste, and minimizes environmental pollution caused by flare combustion. Specifically, by optimizing the gas recovery path, it achieves efficient utilization of by-product gases during production, solving the resource waste problem caused by the direct emission of desorbed gas in traditional processes.

[0016] Furthermore, this application also proposes that the adsorption tower of the PSA device adopts a stacked non-uniformly packed adsorption tower structure to achieve a gradient distribution of adsorbent particle size and porosity.

[0017] Specifically, layered non-uniform packing refers to the arrangement of multiple adsorbent layers within the adsorption tower, with each layer exhibiting a gradient in particle size and porosity. As a preferred embodiment, the adsorption tower is sequentially packed from top to bottom with large-particle-size, low-porosity adsorbent, medium-particle-size, medium-porosity adsorbent, and small-particle-size, high-porosity adsorbent. Further, the particle size gradient of the adsorbent particles can range from 1 to 5 mm, and the porosity gradient can range from 30% to 60%. Thus, adsorbent layers with different particle sizes and porosities can specifically adsorb components with different molecular diameters.

[0018] To address this, this technical solution optimizes the internal structure of the adsorption tower, utilizing the gradient distribution of the physical properties of the adsorbent particles to effectively improve adsorption selectivity and capacity. Compared to traditional uniformly packed adsorption towers, the stacked non-uniform structure makes fuller use of the tower space, reduces channeling during gas flow, and lowers pressure drop losses. Specifically, the large-particle-size, low-porosity adsorbent layer is mainly used for pretreatment and coarse adsorption, the medium-particle-size layer handles the main adsorption process, and the small-particle-size, high-porosity layer is used for deep purification. This significantly improves the staged treatment effect of the entire adsorption process and optimizes system operating efficiency.

[0019] Furthermore, this application proposes that a control valve and a check valve be installed on the mixing pipe. The control valve can be a pneumatic or electric regulating valve for precisely adjusting the flow ratio of the mixed gas; the check valve adopts a swing or lift structure to prevent gas backflow. Specifically, the control valve is remotely and automatically controlled through a DCS system, and the sealing material of the check valve is polytetrafluoroethylene (PTFE) to enhance corrosion resistance.

[0020] The control valve installed in the mixing pipe can dynamically adjust the proportion of desorbed gas mixed in according to the pressure fluctuations of the TSA regenerated gas in the purification synthesis section, avoiding unstable calorific value of the recycled gas due to pressure imbalance. The check valve effectively prevents high-temperature gas from coking furnace flowing back into the PSA desorbed gas system, protecting the performance of the adsorbent in the adsorption tower. Thus, this structure not only solves the energy waste problem caused by the lack of flow control in traditional bypass mixing pipes, but also eliminates the safety hazards caused by backflow.

[0021] As a preferred implementation, the control valve is an intelligent regulating valve with a position feedback signal, which can monitor the opening status in real time and interlock with the TSA system; the check valve is installed 3-5 times the pipe diameter downstream of the control valve to ensure a stable fluid blocking zone. Actual measurements in an alcohol-ammonia production project showed that this configuration increased the desorbed gas utilization rate to over 92% and reduced the flare venting volume by approximately 1500 Nm³.3 / h.

[0022] Furthermore, this application also proposes that a normally closed control valve be installed on the vent pipe.

[0023] Specifically, the normally closed control valve remains closed under normal operating conditions and only opens when the system pressure exceeds a preset safety threshold or when emergency discharge is required. This valve can be electromagnetically or pneumatically driven, controlled by a pressure sensor signal. Furthermore, the valve can be equipped with a manual emergency opening device as a backup operating mode.

[0024] Therefore, by setting a normally closed control valve, precise control of the venting pipeline is achieved, effectively preventing the ineffective discharge of desorbed gas under normal operating conditions. Specifically, when the system pressure is normal, the valve remains closed, forcing all desorbed gas to enter the conversion pipe and participate in subsequent processes; it only automatically opens to release pressure when the system experiences abnormally high pressure, ensuring safe system operation and significantly improving gas recovery rate. This technical solution solves the resource waste problem caused by the direct and continuous venting of desorbed gas in existing technologies, maximizing the utilization of process gas through valve status control. Compared with existing technologies, this solution can reduce effective gas loss by approximately 30% at the same processing scale, while also reducing the operating load of the flare system.

[0025] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A pressure swing adsorption (PSA) desorption gas recovery system, comprising an ammonia PSA unit (1), wherein the desorption gas generated by the PSA unit (1) is split into two paths through a desorption gas pipe (3), one path is sent to a purification conversion preheating furnace (5) through a conversion pipe (4), and the other path is vented to a flare for combustion through a vent pipe (11), characterized in that: The conversion pipe (4) is mixed with the TSA regenerated gas from the purification synthesis section through the bypass mixing pipe (6), and the mixed gas is sent to the coking furnace for use through the return gas pipeline (10).

2. The pressure swing adsorption desorption gas recovery system according to claim 1, characterized in that: The adsorption tower (2) of the PSA device (1) adopts a stacked non-uniformly packed adsorption tower structure to achieve a gradient distribution of adsorbent particle size and porosity.

3. The pressure swing adsorption desorption gas recovery system according to claim 1, characterized in that: The mixing pipe (6) is equipped with a control valve and a check valve.

4. The pressure swing adsorption desorption gas recovery system according to claim 1, characterized in that: A normally closed control valve is installed on the vent pipe (11).

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