Liquid nitrogen washing molecular sieve adsorber pressure equalization system

Abstract

The utility model provides a kind of liquid nitrogen wash molecular sieve adsorber equalizing system, its technical scheme is: including first molecular sieve adsorber and second molecular sieve adsorber, the top of first molecular sieve adsorber is connected with the one end of first pipeline, first pipeline is connected with the one end of second pipeline in parallel, the other end of second pipeline is connected with the one end of equalizing valve group in series, the other end of equalizing valve group is connected with the one end of fifth pipeline in series, the other end of fifth pipeline is connected on sixth pipeline in parallel, the one end of sixth pipeline is connected with the top of second molecular sieve adsorber. Advantageous effect: (1) double flow direction sub-group adaptation alternate equalizing demand;(2) regulating valve accurate control rate;(3) fluid flow resistance is small, promotes equalizing efficiency and equipment safety.

Description

Technical Field

[0001] This utility model belongs to the technical field of coal chemical gas purification equipment, and in particular relates to a liquid nitrogen washing molecular sieve adsorber equalization system, which makes the molecular sieve equalization rate uniform and controllable. Background Technology

[0002] Liquid nitrogen washing is a core step in gas purification during ammonia synthesis, requiring the removal of impurities such as CO, CO2, and CH3OH, which are toxic to the ammonia synthesis catalyst. Molecular sieves are used to adsorb high-boiling-point substances like CO2, CH3OH, and H2O, preventing these substances from solidifying and freezing pipelines and equipment at low temperatures. The molecular sieves employ pressure swing adsorption combined with heated purging, achieving adsorption and regeneration cycles (24-hour cycle) through programmed control, reducing energy consumption and extending the molecular sieve's lifespan.

[0003] Existing liquid nitrogen washing molecular sieve adsorbers typically use a ball valve in series with a shut-off valve for pressure equalization. This means the flow rate is controlled by a single shut-off valve, thus controlling the pressure equalization rate. The shut-off valve is usually designed with a "low inlet, high outlet" configuration, meaning the fluid flows in from below and out from above. Most shut-off valves have flow direction arrows marked on the valve body, and the arrow direction must be consistent with the fluid flow direction in the pipeline during installation. In the correct direction, fluid flow resistance is low; in the reverse direction, fluid flow resistance is high. Therefore, the existing single shut-off valve is difficult to control the pressure equalization rate during reverse flow, resulting in an uncontrollable pressure equalization rate. Summary of the Invention

[0004] To address the problems in the prior art, this utility model provides a liquid nitrogen washing molecular sieve adsorber pressure equalization system. The technical solution includes a first molecular sieve adsorber and a second molecular sieve adsorber. The top of the first molecular sieve adsorber is connected to one end of a first pipeline. The first pipeline and one end of the second pipeline are connected in parallel. The other end of the second pipeline is connected in series with one end of a pressure equalization valve assembly. The other end of the pressure equalization valve assembly is connected in series with one end of a fifth pipeline. The other end of the fifth pipeline is connected in parallel to a sixth pipeline. One end of the sixth pipeline is connected to the top of the second molecular sieve adsorber.

[0005] In a preferred embodiment, the pressure equalizing valve group includes a first subgroup and a second subgroup connected in parallel. The first subgroup includes a third pipeline, on which a first shut-off valve, a first regulating valve, and a first check valve are arranged sequentially from left to right. The second subgroup includes a fourth pipeline, on which a second shut-off valve, a second regulating valve, and a second check valve are arranged sequentially from right to left.

[0006] In a more preferred embodiment, the first shut-off valve is configured to flow to the right with a low inlet and high outlet, meaning the fluid flows in from below the valve disc and out from above, while the first check valve is configured to allow the fluid to flow from left to right.

[0007] In a more preferred embodiment, the second shut-off valve is configured to flow to the left with a low-inlet, high-outlet configuration, meaning the fluid flows in from below the valve disc and out from above, while the second check valve is configured to allow fluid to flow from right to left.

[0008] In a preferred embodiment, the second pipeline is equipped with a track ball valve.

[0009] In a preferred embodiment, the other end of the first pipeline is connected to the nitrogen inlet pipeline and the process gas outlet pipeline via a tee.

[0010] In a preferred embodiment, the other end of the sixth pipeline is connected to the nitrogen inlet pipeline and the process gas outlet pipeline via a tee.

[0011] In a preferred embodiment, the bottom of the first molecular sieve adsorber is provided with a seventh pipeline, which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively via a tee.

[0012] In a preferred embodiment, the bottom of the second molecular sieve adsorber is provided with an eighth pipeline, which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively via a tee.

[0013] In a more preferred embodiment, the track ball valve is a valve whose switch is controlled by the control system program, and both the first regulating valve and the second regulating valve are valves whose opening degree is remotely controlled by the control system.

[0014] The beneficial effects of this utility model are: (1) The first shut-off valve, the first regulating valve, and the first check valve of the first subgroup are all adapted to flow from left to right; the second shut-off valve, the second regulating valve, and the second check valve of the second subgroup are all adapted to flow from right to left. When the first molecular sieve adsorber equalizes the pressure to the second molecular sieve adsorber, the first subgroup is activated; otherwise, the second subgroup is activated. There is no need to use the shut-off valve in reverse, which fundamentally avoids the problems of large reverse flow resistance and rate runaway. (2) The opening of the first and second regulating valves can be remotely adjusted by the control system. The pressure equalization flow rate can be dynamically adjusted according to the pressure difference of the molecular sieve adsorber to ensure that the rate remains uniform and stable regardless of whether the pressure equalization is in the forward or reverse direction, so as to avoid the equipment pressure shock caused by excessively fast pressure equalization or the impact of excessively slow pressure equalization on the adsorption and regeneration cycle efficiency. (3) Both sets of subgroups of shut-off valves are set with "low inlet and high outlet" according to the corresponding flow direction. The fluid flows in from below the valve disc and flows out from above. The flow path is unobstructed and the resistance is much lower than that in the reverse flow state. The pressure equalization process is smoother and the pressure equalization cycle is greatly shortened. The first and second check valves respectively limit the unidirectional flow of the two sets of subgroups to avoid flow interference caused by reverse flow of fluid during the pressure equalization process. This ensures that the pressure equalization path is unique and the flow is stable. At the same time, it prevents the high-pressure side fluid from suddenly backflowing and impacting the low-pressure side adsorber, thus protecting the internal structure of the molecular sieve adsorber from damage. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0016] In the diagram: 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Fourth pipeline; 5. Fifth pipeline; 6. Sixth pipeline; 7. Seventh pipeline; 8. Eighth pipeline; 9. Track ball valve; 10. First shut-off valve; 11. First regulating valve; 12. First check valve; 13. Second shut-off valve; 14. Second regulating valve; 15. Second check valve; 16. First molecular sieve adsorber; 17. Second molecular sieve adsorber. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Example like Figure 1 The liquid nitrogen washing molecular sieve adsorber equalization system shown includes a first molecular sieve adsorber 16 and a second molecular sieve adsorber 17. The top of the first molecular sieve adsorber 16 is connected to one end of the first pipeline 1. The first pipeline 1 is connected in parallel to one end of the second pipeline 2. The other end of the second pipeline 2 is connected in series with one end of the equalization valve group. The other end of the equalization valve group is connected in series with one end of the fifth pipeline 5. The other end of the fifth pipeline 5 is connected in parallel to the sixth pipeline 6. One end of the sixth pipeline 6 is connected to the top of the second molecular sieve adsorber 17.

[0019] Furthermore, the pressure equalization valve group includes a first subgroup and a second subgroup connected in parallel. The first subgroup includes a third pipeline 3, on which a first shut-off valve 10, a first regulating valve 11, and a first check valve 12 are arranged sequentially from left to right. The second subgroup includes a fourth pipeline 4, on which a second shut-off valve 13, a second regulating valve 14, and a second check valve 15 are arranged sequentially from right to left.

[0020] Furthermore, the first shut-off valve 10 is configured to flow to the right with a low inlet and high outlet, meaning the fluid flows in from below the valve disc and out from above, while the first check valve 12 is configured to allow the fluid to flow from left to right.

[0021] Furthermore, the second shut-off valve 13 is configured to flow to the left with a low inlet and high outlet, meaning the fluid flows in from below the valve disc and out from above, while the second check valve 15 is configured to allow the fluid to flow from right to left.

[0022] Furthermore, the second pipeline 2 is equipped with a track ball valve 9.

[0023] Furthermore, the other end of the first pipeline 1 is connected to the nitrogen inlet pipeline and the process gas outlet pipeline respectively via a tee.

[0024] Furthermore, the other end of the sixth pipeline 6 is connected to the nitrogen inlet pipeline and the process gas outlet pipeline respectively via a tee.

[0025] Furthermore, the bottom of the first molecular sieve adsorber 16 is provided with a seventh pipeline 7, which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively through a tee.

[0026] Furthermore, the bottom of the second molecular sieve adsorber 17 is provided with an eighth pipeline 8, which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively through a tee.

[0027] Furthermore, the track ball valve 9 is a valve whose switch is controlled by the control system program, and both the first regulating valve 11 and the second regulating valve 14 are valves whose opening degree is remotely controlled by the control system.

[0028] In the description of this utility model, the terms "left" and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and are not intended to require that this utility model be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this utility model.

[0029] The operation process of the above system is as follows: When the first adsorber 16 is close to saturation and the second adsorber 17 has finished regenerating, the control system first opens the track ball valve 9 on the second pipeline 2 to connect the pressure equalization main passage. Simultaneously, the first subgroup valve in the pressure equalization valve group, which is adapted to the flow direction of "first adsorber → second adsorber", is opened. The first shut-off valve 10 is in the open state with a preset opening degree, and the first regulating valve 11 is opened according to the preset initial opening degree (such as 10%). At this time, the first check valve 12 is automatically opened because the fluid flows from left to right (in accordance with its allowed direction), forming a pressure equalization fluid passage of "top of first adsorber → first pipeline → second pipeline → first subgroup (third pipeline) → fifth pipeline → sixth pipeline → top of second adsorber".

[0030] During the above process, the control system monitors the pressure difference between the two adsorbers in real time. If the pressure difference drops too quickly (exceeding the stable pressure equalization range), the opening of the first regulating valve 11 will be reduced remotely to decrease the fluid flow rate. If the pressure difference decreases too slowly (extending the pressure equalization period), the opening of the first regulating valve is remotely increased to increase the fluid flow rate. During the initial start-up, the opening of the first shut-off valve 10 was experimentally adjusted to a suitable position. The opening of the first shut-off valve 10 was determined to ensure that the opening range of the first regulating valve 11 remained within its reasonable operating range under load fluctuations. For example, if equipment in the upstream or downstream sections malfunctioned but did not shut down, the first check valve 12 was always kept open (due to flow direction matching) to prevent fluid backflow. The second shut-off valve 13 of the second subgroup was preset to the open state, the second regulating valve 14 was always closed, and the second check valve was always closed (due to flow direction mismatch) to avoid interfering with the pressure equalization path.

[0031] When the pressure difference between the two adsorbers drops to the preset value of "close to equilibrium", the control system determines that the pressure equalization is complete, closes the track ball valve 9 on the second pipeline 2, cuts off the main pressure equalization passage, and begins to gradually close the first regulating valve 11 (the opening is reduced from the current value to 0), thus completing the pressure equalization process of "first adsorber → second adsorber".

[0032] When the second adsorber approaches saturation and the first adsorber completes regeneration, reverse pressure equalization is initiated. The process is symmetrical to the forward pressure equalization, with the key difference being the "activation of the second subgroup to adapt to the reverse flow direction." After opening the track ball valve 9, open the second subgroup valve of the equalizing valve group: the second shut-off valve 13 is in the open state with a preset opening degree, and the second regulating valve 14 is opened at the initial opening degree; at this time, the second check valve 15 automatically opens because the fluid flows from right to left (in accordance with its permissible direction), forming a reverse equalizing passage of "top of the second adsorber → sixth pipeline → fifth pipeline → second subgroup (fourth pipeline) → second pipeline → first pipeline → top of the first adsorber".

[0033] The control system remotely adjusts the opening of the second regulating valve 14 according to the pressure difference between the two adsorbers to ensure a stable reverse pressure equalization rate. After the pressure is balanced, the track ball valve 9 and the second regulating valve 13 are closed in sequence to complete the reverse pressure equalization.

[0034] In summary, this system, through its full-process design of "automatic triggering - bidirectional subgroup switching - dynamic rate control - state coordinated switching", achieves stable, controllable and efficient pressure equalization of the liquid nitrogen washing molecular sieve adsorber, perfectly adapts to the process requirements of adsorption-regeneration alternation, and ensures the continuity of the entire purification process without manual intervention.

Claims

1. A liquid nitrogen-washed molecular sieve adsorber pressure equalization system, comprising a first molecular sieve adsorber (16) and a second molecular sieve adsorber (17), characterized in that, The top of the first molecular sieve adsorber (16) is connected to one end of the first pipeline (1), the first pipeline (1) is connected in parallel to one end of the second pipeline (2), the other end of the second pipeline (2) is connected in series with one end of the pressure equalization valve group, the other end of the pressure equalization valve group is connected in series with one end of the fifth pipeline (5), the other end of the fifth pipeline (5) is connected in parallel to the sixth pipeline (6), and one end of the sixth pipeline (6) is connected to the top of the second molecular sieve adsorber (17).

2. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 1, characterized in that, The pressure equalization valve group includes a first subgroup and a second subgroup connected in parallel. The first subgroup includes a third pipeline (3), on which a first shut-off valve (10), a first regulating valve (11) and a first check valve (12) are arranged from left to right. The second subgroup includes a fourth pipeline (4), on which a second shut-off valve (13), a second regulating valve (14) and a second check valve (15) are arranged from right to left.

3. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 2, characterized in that, The first shut-off valve (10) is set in the direction of flow to the right, with low inlet and high outlet, that is, the fluid flows in from below the valve disc and flows out from above. The first check valve (12) is set in the direction of allowing the fluid to flow from left to right.

4. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 2, characterized in that, The second shut-off valve (13) is set in the direction of flow to the left, with low inlet and high outlet, that is, the fluid flows in from below the valve disc and flows out from above. The second check valve (15) is set in the direction of allowing the fluid to flow from right to left.

5. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 2, characterized in that, The second pipeline (2) is equipped with a track ball valve (9).

6. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 1, characterized in that, The other end of the first pipeline (1) is connected to the nitrogen inlet pipeline and the process gas outlet pipeline respectively via a tee.

7. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 1, characterized in that, The other end of the sixth pipeline (6) is connected to the nitrogen inlet pipeline and the process gas outlet pipeline respectively via a tee.

8. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 1, characterized in that, The bottom of the first molecular sieve adsorber (16) is provided with a seventh pipeline (7), which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively through a tee.

9. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 1, characterized in that, The bottom of the second molecular sieve adsorber (17) is provided with an eighth pipeline (8), which is connected to the nitrogen outlet pipeline and the process gas inlet pipeline respectively through a tee.

10. The pressure equalization system for liquid nitrogen washing of molecular sieve adsorbers according to claim 5, characterized in that, The track ball valve (9) is a valve whose switch is controlled by the control system program. The first regulating valve (11) and the second regulating valve (14) are both valves whose opening degree is remotely controlled by the control system.

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