Energy-saving production system of ammonia centrifugal compressor

Abstract

The utility model discloses an energy-saving production system of an ammonia centrifugal compressor, belongs to ammonia synthesis equipment in the coal chemical industry, and aims to solve the technical problem of how to reduce the temperature of each compressed gas entering the compressor and effectively reduce the energy consumption requirement of the corresponding compressor. According to the technical scheme, the system comprises a first-stage ammonia compressor, a second-stage ammonia compressor, a third-stage ammonia compressor and a fourth-stage ammonia compressor, the first-stage ammonia compressor is connected with the second-stage ammonia compressor in series, and the second-stage ammonia compressor is communicated with the third-stage ammonia compressor through a second-stage ammonia compressor outlet pipeline and a third-stage ammonia compressor inlet pipeline; the third-stage ammonia compressor is communicated with the fourth-stage ammonia compressor through a third-stage ammonia compressor outlet pipeline and a fourth-stage ammonia compressor inlet pipeline, a fourth-stage ammonia compressor outlet pipeline is arranged at the outlet end of the fourth-stage ammonia compressor, and a final-stage cooler is arranged on the fourth-stage ammonia compressor outlet pipeline; and the inlet end of the final-stage cooler is communicated with an outlet pipeline of the fourth-stage ammonia compressor.

Description

Technical Field

[0001] The utility model relates to coal chemical industry synthetic ammonia equipment, specifically an ammonia centrifugal compressor energy-saving production system. Background Art

[0002] In the current coal chemical ammonia synthesis process, the ammonia compressor, a key refrigeration device, provides cooling for the five low-temperature methanol wash ammonia coolers and the two-stage ammonia synthesis cooler. The ammonia centrifugal compressor utilizes a four-stage compression system. The ammonia return gas from the low-temperature methanol wash section is compressed in the first stage and then mixed with the second-stage ammonia return gas from the ammonia synthesis section before entering the second stage. After exiting the second stage, the gas is mixed with the first-stage ammonia return gas from the synthesis section before entering the third and fourth stages. A water cooler is installed between the third and fourth stages to cool the high-temperature ammonia gas and improve compression efficiency. Because the uncooled ammonia gas at the outlet of the second stage is directly mixed with the first-stage ammonia return gas from the synthesis section before entering the third stage, its temperature is too high. This reduces the isothermal compression efficiency of the compressor and increases system energy consumption.

[0003] In order to ensure stable operation, the ammonia compressor is equipped with an anti-surge circuit, which uses the ammonia gas after the final stage cooler at the compressor outlet to return to the inlet of the 1st, 2nd and 3rd compression stages as needed. Affected by the pressure stage air temperature and load, the partial anti-surge opening is about 13%-17%. Since the gas phase ammonia temperature in this circuit is relatively high, after mixing with the low-temperature methanol scrubber ammonia return gas, the inlet temperature of the ammonia compressor is increased, which further causes high consumption of the ammonia compressor.

[0004] Therefore, how to lower the temperature of each compressed gas entering the compressor and effectively reduce the energy consumption demand of the corresponding compressor is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The technical task of the utility model is to provide an energy-saving production system for an ammonia centrifugal compressor to solve the problem of how to reduce the temperature of each compressed gas entering the compressor and effectively reduce the energy consumption demand of the corresponding compressor.

[0006] The technical task of the utility model is achieved in the following manner: an ammonia centrifugal compressor energy-saving production system comprises a first-stage ammonia compressor, a second-stage ammonia compressor, a third-stage ammonia compressor and a fourth-stage ammonia compressor, the first-stage ammonia compressor and the second-stage ammonia compressor are connected in series, the second-stage ammonia compressor is connected to the third-stage ammonia compressor through the second-stage ammonia compressor outlet pipe and the third-stage ammonia compressor inlet pipe, the third-stage ammonia compressor is connected to the fourth-stage ammonia compressor through the third-stage ammonia compressor outlet pipe and the fourth-stage ammonia compressor inlet pipe, the outlet end of the fourth-stage ammonia compressor is provided with a fourth-stage ammonia compressor outlet pipe, the fourth-stage ammonia compressor outlet pipe is provided with a final-stage cooler, the inlet end of the final-stage cooler is connected to the fourth-stage ammonia compressor outlet pipe, the outlet end of the final-stage cooler is divided into two paths, one path is a liquid ammonia recovery pipeline, and the other path is an anti-surge pipeline;

[0007] Among them, the anti-surge pipeline includes an anti-surge main pipe, which is divided into three routes, namely the first-stage ammonia compressor anti-surge pipeline, the second-stage ammonia compressor anti-surge pipeline and the third-stage ammonia compressor anti-surge pipeline. The first-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the first-stage ammonia compressor through the first-stage ammonia compressor inlet anti-surge valve, the second-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the second-stage ammonia compressor through the second-stage ammonia compressor inlet anti-surge valve, and the third-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the third-stage ammonia compressor through the third-stage ammonia compressor inlet anti-surge valve.

[0008] Preferably, a first-stage ammonia compressor inlet pipe is provided at the inlet end of the first-stage ammonia compressor, one end of the first-stage ammonia compressor inlet pipe is connected to the inlet end of the first-stage ammonia compressor, and the other end of the first-stage ammonia compressor inlet pipe is used to connect to the low-temperature methanol washing section gas pipeline;

[0009] One end of the anti-surge pipeline of the first-stage ammonia compressor is connected to the anti-surge main pipe, and the other end of the anti-surge pipeline of the first-stage ammonia compressor is connected to the inlet pipeline of the first-stage ammonia compressor.

[0010] More preferably, the inlet end of the second-stage ammonia compressor is provided with a second-stage ammonia compressor inlet pipe, one end of the second-stage ammonia compressor inlet pipe is connected to the inlet end of the second-stage ammonia compressor, and the other end of the second-stage ammonia compressor inlet pipe is used to connect to the ammonia synthesis secondary ammonia refrigeration gas pipeline;

[0011] One end of the second-stage ammonia compressor anti-surge pipeline is connected to the anti-surge main pipe, and the other end of the second-stage ammonia compressor anti-surge pipeline is connected to the second-stage ammonia compressor inlet pipeline.

[0012] More preferably, a secondary cooler and a secondary ammonia cooler are provided on the outlet pipeline of the second-stage ammonia compressor.

[0013] More preferably, the inlet end of the third-stage ammonia compressor is provided with a third-stage ammonia compressor inlet pipe, one end of the third-stage ammonia compressor inlet pipe is connected to the inlet end of the third-stage ammonia compressor, and the other end of the third-stage ammonia compressor inlet pipe is used to connect to the first-stage ammonia refrigeration gas pipe of the ammonia synthesis;

[0014] One end of the anti-surge pipeline of the third-stage ammonia compressor is connected to the anti-surge main pipe, and the other end of the anti-surge pipeline of the third-stage ammonia compressor is connected to the inlet pipeline of the third-stage ammonia compressor.

[0015] More preferably, the liquid ammonia recovery pipeline includes an ammonia recovery pipeline, an ammonia condenser and a liquid ammonia storage tank are provided on the ammonia recovery pipeline, and a liquid ammonia delivery pipeline is provided at the outlet end of the liquid ammonia storage tank. One end of the liquid ammonia delivery pipeline is connected to the liquid ammonia storage tank, and the other end of the liquid ammonia delivery pipeline is used to be connected to the liquid ammonia deammonification synthesis pipeline and the low-temperature methanol washing device, and a liquid ammonia delivery valve is provided on the liquid ammonia delivery pipeline.

[0016] More preferably, the outlet end of the liquid ammonia storage tank is further provided with a secondary ammonia cooler liquid ammonia inlet pipe, one end of the secondary ammonia cooler liquid ammonia inlet pipe is connected to the liquid ammonia storage tank, and the other end of the secondary ammonia cooler liquid ammonia inlet pipe is connected to the secondary ammonia cooler, and a secondary ammonia cooler liquid ammonia inlet valve is provided on the secondary ammonia cooler liquid ammonia inlet pipe.

[0017] More preferably, the secondary ammonia cooler is provided with a secondary ammonia cooler gas ammonia outlet pipe, one end of the secondary ammonia cooler gas ammonia outlet pipe is connected to the outlet end of the secondary ammonia cooler, the other end of the secondary ammonia cooler gas ammonia outlet pipe is connected to the third-stage ammonia compressor anti-surge pipe, and the secondary ammonia cooler gas ammonia outlet pipe is provided with a third-stage gas ammonia deammonification compressor inlet anti-surge valve.

[0018] More preferably, the second-stage ammonia compressor anti-surge pipeline is connected to the secondary ammonia cooler gas ammonia outlet pipeline through the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline, and the second-stage gas ammonia deammonification compressor inlet anti-surge valve is provided on the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline.

[0019] More preferably, the first-stage ammonia compressor anti-surge pipeline is connected to the secondary ammonia cooler gas ammonia outlet pipeline through the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline, and the first-stage gas ammonia deammonification compressor inlet anti-surge valve is provided on the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline.

[0020] The ammonia centrifugal compressor energy-saving production system of the utility model has the following advantages:

[0021] (1) The present invention reduces the temperature of each compressed gas entering the compressor, which can effectively reduce the energy consumption requirements of the corresponding compression stage. For ammonia compressor production systems, for every 3°C reduction in the inlet temperature, the energy consumption of the corresponding compression stage decreases by about 1%. The inter-stage gas is further cooled, which improves the compressor efficiency and reduces energy consumption. The cooling effect is not only related to the heat transfer performance of the cooler, but also to the circulation volume and temperature on the cold source side. Conventional methods cannot significantly improve the compressor performance by optimizing the heat exchanger alone due to the circulating water temperature limit.

[0022] (2) The utility model adds a set of circulating water heat exchangers in series on the gas phase pipeline at the outlet of the second-stage ammonia compressor to cool the high-temperature gas ammonia at the outlet of the second compression stage, and uses the surplus of the existing circulating water system to preliminarily cool the high-temperature gas ammonia at the outlet of the second-stage ammonia compressor;

[0023] (3) The utility model connects a circulating water heat exchanger in series with the gas phase pipeline at the outlet of the second-stage ammonia compressor and then adds an ammonia evaporative cooler in series. The liquid ammonia in the liquid ammonia storage tank of the utility model is used, and the evaporated ammonia is returned to the inlet of the first to third stages respectively, replacing the high-temperature gas ammonia at the outlet of the final cooler, and at the same time achieving the purpose of further cooling and reducing the consumption of the compressed gas ammonia at the outlet of the second-stage ammonia compressor;

[0024] (4) The utility model adds two coolers in series to reduce the outlet temperature of the second compression stage, that is, to reduce the inlet temperature of the third compression stage in a step-by-step manner. For every 24°C reduction in the inlet temperature, the energy consumption of the corresponding compression stage decreases by about 8%;

[0025] (5) The utility model fully closes the anti-surge valve at the inlet of the first-stage ammonia compressor, the anti-surge valve at the inlet of the second-stage ammonia compressor, and the anti-surge valve at the inlet of the third-stage ammonia compressor, thereby reducing ineffective return air and reducing the energy consumption of the corresponding compression stage by about 2%-4%.

[0026] The utility model has the characteristics of reasonable design, simple structure, easy processing, small size, convenient use, and multiple uses, and therefore has good promotion and use value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings.

[0028] Attachment Figure 1 This is a structural diagram of the ammonia centrifugal compressor energy-saving production system.

[0029] In the figure: 1. First-stage ammonia compressor inlet pipeline, 2. First-stage ammonia compressor, 3. Second-stage ammonia compressor inlet pipeline, 4. Second-stage ammonia compressor, 5. Second-stage cooler, 6. Second-stage ammonia cooler, 7. Third-stage ammonia compressor inlet pipeline, 8. Third-stage ammonia compressor, 9. Interstage cooler, 10. Fourth-stage ammonia compressor inlet pipeline, 11. Fourth-stage ammonia compressor, 12. Final-stage cooler, 13. Ammonia condenser, 14. Anti-surge main pipe, 15. Liquid ammonia storage tank, 16. Liquid ammonia inlet pipeline of second-stage ammonia cooler, 17. Third-stage ammonia compressor inlet anti-surge valve, 18. Second-stage ammonia compressor inlet anti-surge valve, 19. First-stage ammonia compressor inlet anti-surge valve, 20. Third-stage ammonia compressor anti-surge pipeline, 21. Second-stage ammonia compressor anti-surge pipeline, 22. 1. Anti-surge pipeline of the first-stage ammonia compressor, 23. Gas ammonia outlet pipeline of the second-stage ammonia cooler, 24. Anti-surge valve at the inlet of the third-stage gas ammonia de-ammonia compressor, 25. Anti-surge valve at the inlet of the first-stage gas ammonia de-ammonia compressor, 26. Anti-surge valve at the inlet of the second-stage gas ammonia de-ammonia compressor, 27. Liquid ammonia inlet valve of the second-stage ammonia cooler, 28. Liquid ammonia export valve, 29. Anti-surge pipeline at the inlet of the second-stage gas ammonia de-ammonia compressor, 30. Anti-surge pipeline at the inlet of the first-stage gas ammonia de-ammonia compressor, 31. Liquid ammonia export pipeline, 32. Outlet pipeline of the second-stage ammonia compressor, 33. Outlet pipeline of the third-stage ammonia compressor, 34. Outlet pipeline of the fourth-stage ammonia compressor, 35. Ammonia recovery pipeline, 36. Inlet gas pipeline of the low-temperature methanol washing section, 37. Inlet gas pipeline of the second-stage ammonia cooling section of ammonia synthesis, 38. Inlet gas pipeline of the first-stage ammonia cooling section of ammonia synthesis. DETAILED DESCRIPTION

[0030] An energy-saving ammonia centrifugal compressor production system of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] In the description of this utility model, it should be understood that terms such as "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate positions or locations based on the positions or locations shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific manner, and therefore should not be construed as limitations of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0033] Example:

[0034] As attached Figure 1 As described above, this embodiment provides an ammonia centrifugal compressor energy-saving production system, which structure includes a first-stage ammonia compressor 2, a second-stage ammonia compressor 4, a third-stage ammonia compressor 8 and a fourth-stage ammonia compressor 11. The first-stage ammonia compressor 2 and the second-stage ammonia compressor 4 are connected in series, the second-stage ammonia compressor 4 is connected to the third-stage ammonia compressor 8 through the second-stage ammonia compressor outlet pipe 32 and the third-stage ammonia compressor inlet pipe 7, the third-stage ammonia compressor 8 is connected to the fourth-stage ammonia compressor 11 through the third-stage ammonia compressor outlet pipe 33 and the fourth-stage ammonia compressor inlet pipe 10, the outlet end of the fourth-stage ammonia compressor 11 is installed with a fourth-stage ammonia compressor outlet pipe 34, the fourth-stage ammonia compressor outlet pipe 34 is installed on the final-stage cooler 12, and the inlet end of the final-stage cooler 12 is connected to the fourth-stage ammonia compressor outlet The inlet pipe 34 is connected, and the outlet end of the final cooler 12 is divided into two routes, one is a liquid ammonia recovery pipeline, and the other is an anti-surge pipeline; wherein, the anti-surge pipeline includes an anti-surge main pipe 14, and the anti-surge main pipe 14 is divided into three routes, namely the first-stage ammonia compressor anti-surge pipeline 22, the second-stage ammonia compressor anti-surge pipeline 21 and the third-stage ammonia compressor anti-surge pipeline 20. The first-stage ammonia compressor anti-surge pipeline 22 is connected to the inlet end of the first-stage ammonia compressor 2 through the first-stage ammonia compressor inlet anti-surge valve 19, the second-stage ammonia compressor anti-surge pipeline 21 is connected to the inlet end of the second-stage ammonia compressor 4 through the second-stage ammonia compressor inlet anti-surge valve 18, and the third-stage ammonia compressor anti-surge pipeline 20 is connected to the inlet end of the third-stage ammonia compressor 8 through the third-stage ammonia compressor inlet anti-surge valve 17.

[0035] In this embodiment, the inlet end of the first-stage ammonia compressor 2 is installed with a first-stage ammonia compressor inlet pipe 1, one end of the first-stage ammonia compressor inlet pipe 1 is connected to the inlet end of the first-stage ammonia compressor 2, and the other end of the first-stage ammonia compressor inlet pipe 1 is used to connect to the low-temperature methanol washing section gas pipeline 36; one end of the first-stage ammonia compressor anti-surge pipe 22 is connected to the anti-surge main pipe 14, and the other end of the first-stage ammonia compressor anti-surge pipe 22 is connected to the first-stage ammonia compressor inlet pipe 1.

[0036] In this embodiment, a second-stage ammonia compressor inlet pipe 3 is installed at the inlet end of the second-stage ammonia compressor 4. One end of the second-stage ammonia compressor inlet pipe 3 is connected to the inlet end of the second-stage ammonia compressor 4, and the other end of the second-stage ammonia compressor inlet pipe 3 is used to connect to the ammonia synthesis secondary ammonia cold air pipe 37; one end of the second-stage ammonia compressor anti-surge pipe 21 is connected to the anti-surge main pipe 14, and the other end of the second-stage ammonia compressor anti-surge pipe 21 is connected to the second-stage ammonia compressor inlet pipe 3.

[0037] In this embodiment, a secondary cooler 5 and a secondary ammonia cooler 6 are installed on the second-stage ammonia compressor outlet pipe 32 .

[0038] The inlet end of the third-stage ammonia compressor 8 in this embodiment is equipped with a third-stage ammonia compressor inlet pipe 7, one end of the third-stage ammonia compressor inlet pipe 7 is connected to the inlet end of the third-stage ammonia compressor 8, and the other end of the third-stage ammonia compressor inlet pipe 7 is used to connect to the ammonia synthesis first-stage ammonia cold air pipe 38; one end of the third-stage ammonia compressor anti-surge pipe 20 is connected to the anti-surge main pipe 14, and the other end of the third-stage ammonia compressor anti-surge pipe 20 is connected to the third-stage ammonia compressor inlet pipe 7.

[0039] The liquid ammonia recovery pipeline in this embodiment includes an ammonia recovery pipeline 35, on which an ammonia condenser 13 and a liquid ammonia storage tank 15 are installed. A liquid ammonia delivery pipeline 31 is installed at the outlet end of the liquid ammonia storage tank 15. One end of the liquid ammonia delivery pipeline 31 is connected to the liquid ammonia storage tank 15, and the other end of the liquid ammonia delivery pipeline 31 is used to be connected to the liquid ammonia deammonification synthesis pipeline and the low-temperature methanol washing device. A liquid ammonia delivery valve 28 is installed on the liquid ammonia delivery pipeline 31.

[0040] A secondary ammonia cooler liquid ammonia inlet pipe 16 is also installed at the outlet end of the liquid ammonia storage tank 15 in this embodiment. One end of the secondary ammonia cooler liquid ammonia inlet pipe 16 is connected to the liquid ammonia storage tank 15, and the other end of the secondary ammonia cooler liquid ammonia inlet pipe 16 is connected to the secondary ammonia cooler 6. A secondary ammonia cooler liquid ammonia inlet valve 27 is installed on the secondary ammonia cooler liquid ammonia inlet pipe 16.

[0041] A secondary ammonia cooler gas ammonia outlet pipe 23 is installed on the secondary ammonia cooler 6 in this embodiment. One end of the secondary ammonia cooler gas ammonia outlet pipe 23 is connected to the outlet end of the secondary ammonia cooler 6, and the other end of the secondary ammonia cooler gas ammonia outlet pipe 23 is connected to the third-stage ammonia compressor anti-surge pipe 20. The secondary ammonia cooler gas ammonia outlet pipe 23 is installed with a third-stage gas ammonia deammonification compressor inlet anti-surge valve 24.

[0042] In this embodiment, the second-stage ammonia compressor anti-surge pipeline 21 is connected to the secondary ammonia cooler gas ammonia outlet pipeline 23 through the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline 29, and the second-stage gas ammonia deammonification compressor inlet anti-surge valve 26 is installed on the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline 29.

[0043] In this embodiment, the first-stage ammonia compressor anti-surge pipeline 22 is connected to the secondary ammonia cooler gas ammonia outlet pipeline 23 through the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline 30, and the first-stage gas ammonia deammonification compressor inlet anti-surge valve 25 is installed on the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline 30.

[0044] The working process of this embodiment is specifically as follows: in normal production of synthetic ammonia, the low-temperature -33°C vacuum pressure -35kpa ammonia from the low-temperature methanol washing device is connected to the first-stage ammonia compressor 2 through the first-stage ammonia compressor inlet pipe 1. After the medium gas ammonia is compressed and the pressure and temperature are increased, it is mixed with the ammonia from the second-stage ammonia compressor inlet pipe 3 in the compressor cylinder to synthesize the secondary ammonia cold gas ammonia and enter the second-stage ammonia compressor 4. After compression and pressure increase and temperature increase, the gas ammonia enters the newly added secondary cooler 5 through the outlet pipe. The high-temperature gas ammonia entering the secondary cooler 5 exchanges heat with the circulating cooling water in the pipe to reduce the temperature and is connected to the inlet of the newly added secondary ammonia cooler 6 through the outlet pipe. The normal-temperature gas ammonia entering the secondary ammonia cooler exchanges heat with the low-temperature ammonia evaporated at low pressure in the pipe to reduce the temperature. The ammonia synthesis from the third-stage ammonia compressor inlet pipe 7 is mixed with the first-stage ammonia cold gas and connected to the inlet of the third-stage ammonia compressor 8. After the third-stage compression and pressure increase, the gas temperature is increased. After the outlet pipe is connected to the inter-stage cooler 9, and after cooling by the shell-side circulating water, the gas ammonia is connected to the inlet of the fourth-stage compressor 11 through the fourth-stage compressor inlet pipe 10. After the fourth-stage compression and pressure increase, the gas temperature is increased. After the outlet pipe is connected to the final-stage cooler 12, the shell-side circulating water of the final-stage cooler 12 is initially cooled to a medium temperature of about 50°C. The gas is divided into two streams. Most of the medium-temperature gas ammonia is connected to the inlet of the ammonia cooler 13 through a pipeline, and is cooled by the shell-side circulating water of the ammonia condenser. The tube-side gas phase is condensed into liquid phase. Most of the liquid ammonia is then sent to the ammonia synthesis and low-temperature methanol washing ammonia devices through the liquid ammonia export valve 28 on the pipeline. A portion of the liquid ammonia passes through the secondary ammonia cooler liquid ammonia inlet valve 27 and the secondary ammonia cooler liquid ammonia inlet pipe 16 to the shell side inlet of the secondary ammonia cooler 6. The shell side liquid ammonia absorbs the high-temperature heat in the tube side by adopting the partition heat exchange method and is flash-evaporated into gaseous ammonia at low pressure. Then, one stream passes through the secondary ammonia cooler outlet pipe 23, passes through the third-stage gas ammonia deammonification compressor inlet anti-surge valve 24 to be connected to the third-stage ammonia compressor anti-surge pipe 20, the second stream passes through the first-stage gas ammonia deammonification compressor inlet anti-surge valve 25 to be connected to the first-stage ammonia compressor anti-surge pipe 22, and the third stream passes through the second-stage gas ammonia deammonification compressor inlet anti-surge valve 26 to be connected to the second-stage ammonia compressor anti-surge pipe 21. Through these three streams of gaseous ammonia, the purpose of closing the third-stage ammonia compressor inlet anti-surge valve 18, and the first-stage ammonia compressor inlet anti-surge valve 19 is achieved, thereby reducing ineffective anti-surge return gas medium and lowering compressor energy consumption.

[0045] During the start-up and shutdown, load fluctuation or accident conditions of the synthetic ammonia system, the load of the ammonia synthesis and low-temperature methanol washing devices is unstable, which will cause the inlet gas volume and total load of each stage of the ammonia compressor to be unstable, and the centrifugal compressor surge is likely to occur. The gas is initially cooled to a medium temperature of about 50°C by the shell-side circulating water of the final-stage cooler 12. Under the above-mentioned special conditions, it passes through the anti-surge main pipe 14, the third-stage ammonia compressor inlet anti-surge valve 17, the third-stage ammonia compressor anti-surge pipeline 20 to be connected to the third-stage ammonia compressor inlet pipeline 7; passes through the second-stage ammonia compressor inlet anti-surge valve 18, the second-stage ammonia compressor anti-surge pipeline 21 to be connected to the second-stage ammonia compressor inlet pipeline 3; passes through the first-stage ammonia compressor inlet anti-surge valve 19, the first-stage ammonia compressor anti-surge pipeline 22 to be connected to the first-stage ammonia compressor inlet pipeline 1, enters the ammonia compressor, is compressed, condensed, liquefied and enters the next cycle.

[0046] Under steady-state conditions, by adjusting the shell-side circulating water volume and temperature parameters of the newly added secondary cooler 5, the inlet temperature of the process medium gas ammonia entering the third-stage ammonia compressor 8 is lowered, thereby reducing the energy consumption of the compressor.

[0047] Under steady-state conditions, the amount of liquid ammonia in the shell side of the newly added secondary ammonia cooler 6 is adjusted through the liquid ammonia inlet valve 27 of the secondary ammonia cooler, further reducing the ammonia temperature of the outlet gas of the secondary cooler 5 and further reducing the inlet temperature of the third-stage ammonia compressor 8, thereby reducing the energy consumption of the compressor.

[0048] The gas ammonia at the shell side outlet of the secondary ammonia cooler 6 passes through the anti-surge valve 24 at the inlet of the third-stage gas ammonia deammonification compressor, and the gas ammonia evaporation pressure is adjusted to 0.38MPa and the temperature to 3°C, thereby increasing the inlet gas volume load of the third-stage ammonia compressor 8. This achieves the purpose of closing the anti-surge valve 17 at the inlet of the third-stage ammonia compressor when the ammonia cooling load of the first stage of ammonia synthesis fluctuates, thereby reducing the return air loss of the compressor.

[0049] The gas ammonia at the shell side outlet of the secondary ammonia cooler 6 passes through the anti-surge valve 26 at the inlet of the second-stage gas ammonia deammonification compressor, and the gas ammonia evaporation pressure is adjusted to 0.25MPa and the temperature to -8°C, thereby increasing the inlet gas volume load of the second-stage ammonia compressor 4. This achieves the purpose of closing the anti-surge valve 18 at the inlet of the third-stage ammonia compressor when the ammonia cooling load of the first stage of ammonia synthesis fluctuates, thereby reducing the return air loss of the compressor.

[0050] The gas ammonia at the shell side outlet of the secondary ammonia cooler 6 passes through the anti-surge valve 25 at the inlet of the first-stage gas ammonia deammonification compressor, and the gas ammonia evaporation pressure is adjusted to -33KPa and the temperature to -35℃, which increases the inlet gas volume load of the first-stage ammonia compressor 2, and achieves the purpose of closing the anti-surge valve 19 at the inlet of the third-stage ammonia compressor when the ammonia cooling load of the first stage of ammonia synthesis fluctuates, thereby reducing the return air loss of the compressor.

[0051] During the start-up, shutdown, or accident conditions of the ammonia synthesis system, when the load of the low-temperature methanol washing device changes, the anti-surge valve 17 at the inlet of the first-stage ammonia compressor is adjusted to introduce part of the ammonia gas at the outlet of the final-stage cooler 12 into the first-stage ammonia compressor 2, thereby increasing the ineffective return air volume of the compressor and ensuring that the first-stage ammonia compressor 2 operates stably in the anti-surge range.

[0052] When the ammonia synthesis system is started, shut down or in an accident, and the secondary ammonia cooling load of the ammonia synthesis changes, the anti-surge valve 18 at the inlet of the second-stage ammonia compressor is adjusted to introduce the ammonia portion of the outlet gas of the final-stage cooler 12 into the second-stage ammonia compressor 4, thereby increasing the ineffective return air volume of the compressor and ensuring that the second-stage ammonia compressor 4 operates stably in the anti-surge range.

[0053] When the ammonia synthesis system is started, shut down or in an accident, and the cooling load of the first stage ammonia synthesis changes, the anti-surge valve 17 at the inlet of the third-stage ammonia compressor is adjusted to introduce part of the ammonia gas at the outlet of the final-stage cooler 12 into the third-stage ammonia compressor 8, thereby increasing the ineffective return air volume of the compressor and ensuring that the third-stage ammonia compressor 8 operates stably in the anti-surge range.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ammonia centrifugal compressor energy-saving production system, characterized in that: The system comprises a first-stage ammonia compressor, a second-stage ammonia compressor, a third-stage ammonia compressor and a fourth-stage ammonia compressor, wherein the first-stage ammonia compressor and the second-stage ammonia compressor are connected in series, the second-stage ammonia compressor is connected to the third-stage ammonia compressor via the second-stage ammonia compressor outlet pipe and the third-stage ammonia compressor inlet pipe, the third-stage ammonia compressor is connected to the fourth-stage ammonia compressor via the third-stage ammonia compressor outlet pipe and the fourth-stage ammonia compressor inlet pipe, the outlet end of the fourth-stage ammonia compressor is provided with a fourth-stage ammonia compressor outlet pipe, the outlet pipe of the fourth-stage ammonia compressor is provided with a final-stage cooler, the inlet end of the final-stage cooler is connected to the outlet pipe of the fourth-stage ammonia compressor, and the outlet end of the final-stage cooler is divided into two routes, one is a liquid ammonia recovery pipeline, and the other is an anti-surge pipeline; Among them, the anti-surge pipeline includes an anti-surge main pipe, which is divided into three routes, namely the first-stage ammonia compressor anti-surge pipeline, the second-stage ammonia compressor anti-surge pipeline and the third-stage ammonia compressor anti-surge pipeline. The first-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the first-stage ammonia compressor through the first-stage ammonia compressor inlet anti-surge valve, the second-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the second-stage ammonia compressor through the second-stage ammonia compressor inlet anti-surge valve, and the third-stage ammonia compressor anti-surge pipeline is connected to the inlet end of the third-stage ammonia compressor through the third-stage ammonia compressor inlet anti-surge valve.

2. The ammonia centrifugal compressor energy-saving production system according to claim 1, characterized in that: The inlet end of the first-stage ammonia compressor is provided with a first-stage ammonia compressor inlet pipe, one end of the first-stage ammonia compressor inlet pipe is connected to the inlet end of the first-stage ammonia compressor, and the other end of the first-stage ammonia compressor inlet pipe is used to connect to the low-temperature methanol washing section gas pipeline; One end of the anti-surge pipeline of the first-stage ammonia compressor is connected to the anti-surge main pipe, and the other end of the anti-surge pipeline of the first-stage ammonia compressor is connected to the inlet pipeline of the first-stage ammonia compressor.

3. The ammonia centrifugal compressor energy-saving production system according to claim 1 or 2, characterized in that: The inlet end of the second-stage ammonia compressor is provided with a second-stage ammonia compressor inlet pipe, one end of the second-stage ammonia compressor inlet pipe is connected to the inlet end of the second-stage ammonia compressor, and the other end of the second-stage ammonia compressor inlet pipe is used to connect to the ammonia synthesis secondary ammonia cooling gas pipe; One end of the second-stage ammonia compressor anti-surge pipeline is connected to the anti-surge main pipe, and the other end of the second-stage ammonia compressor anti-surge pipeline is connected to the second-stage ammonia compressor inlet pipeline.

4. The ammonia centrifugal compressor energy-saving production system according to claim 3, characterized in that: A secondary cooler and a secondary ammonia cooler are provided on the outlet pipeline of the second-stage ammonia compressor.

5. The ammonia centrifugal compressor energy-saving production system according to claim 4, characterized in that: The inlet end of the third-stage ammonia compressor is provided with a third-stage ammonia compressor inlet pipe, one end of the third-stage ammonia compressor inlet pipe is connected to the inlet end of the third-stage ammonia compressor, and the other end of the third-stage ammonia compressor inlet pipe is used to connect to the first-stage ammonia refrigeration gas pipeline of the ammonia synthesis; One end of the anti-surge pipeline of the third-stage ammonia compressor is connected to the anti-surge main pipe, and the other end of the anti-surge pipeline of the third-stage ammonia compressor is connected to the inlet pipeline of the third-stage ammonia compressor.

6. The ammonia centrifugal compressor energy-saving production system according to claim 5, characterized in that: The liquid ammonia recovery pipeline includes an ammonia recovery pipeline, an ammonia condenser and a liquid ammonia storage tank are provided on the ammonia recovery pipeline, and a liquid ammonia delivery pipeline is provided at the outlet end of the liquid ammonia storage tank. One end of the liquid ammonia delivery pipeline is connected to the liquid ammonia storage tank, and the other end of the liquid ammonia delivery pipeline is used to be connected to the liquid ammonia deammonification synthesis pipeline and the low-temperature methanol washing device. A liquid ammonia delivery valve is provided on the liquid ammonia delivery pipeline.

7. The ammonia centrifugal compressor energy-saving production system according to claim 6, characterized in that: The outlet end of the liquid ammonia storage tank is also provided with a secondary ammonia cooler liquid ammonia inlet pipe, one end of the secondary ammonia cooler liquid ammonia inlet pipe is connected to the liquid ammonia storage tank, and the other end of the secondary ammonia cooler liquid ammonia inlet pipe is connected to the secondary ammonia cooler, and a secondary ammonia cooler liquid ammonia inlet valve is provided on the secondary ammonia cooler liquid ammonia inlet pipe.

8. The ammonia centrifugal compressor energy-saving production system according to claim 7, characterized in that: The secondary ammonia cooler is provided with a secondary ammonia cooler gas ammonia outlet pipe, one end of the secondary ammonia cooler gas ammonia outlet pipe is connected to the outlet end of the secondary ammonia cooler, the other end of the secondary ammonia cooler gas ammonia outlet pipe is connected to the third-stage ammonia compressor anti-surge pipe, and the secondary ammonia cooler gas ammonia outlet pipe is provided with a third-stage gas ammonia deammonification compressor inlet anti-surge valve.

9. The ammonia centrifugal compressor energy-saving production system according to claim 8, characterized in that: The second-stage ammonia compressor anti-surge pipeline is connected to the secondary ammonia cooler gas ammonia outlet pipeline through the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline, and the second-stage gas ammonia deammonification compressor inlet anti-surge valve is provided on the second-stage gas ammonia deammonification compressor inlet anti-surge pipeline.

10. The ammonia centrifugal compressor energy-saving production system according to claim 9, characterized in that: The first-stage ammonia compressor anti-surge pipeline is connected to the secondary ammonia cooler gas ammonia outlet pipeline through the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline, and the first-stage gas ammonia deammonification compressor inlet anti-surge valve is provided on the first-stage gas ammonia deammonification compressor inlet anti-surge pipeline.

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