A high-pressure liquid phase decompression energy recovery system for a urea plant

Abstract

The utility model discloses a high-pressure liquid phase decompression energy recovery system for a urea device, which mainly comprises a high-pressure stripping tower (1), a high-pressure accumulator (2), a hydraulic turbine power generation device (3) and a medium-pressure decomposition tower (4). The high-pressure stripping tower (1), the high-pressure accumulator (2), the hydraulic turbine power generation device (3) and the medium-pressure decomposition tower (4) are roughly connected in series, and functional valves are arranged between the devices to participate in interlocking and regulation. A high-pressure accumulator is arranged in the system to ensure that the turbine power generation device and the medium-pressure decomposition tower can operate smoothly while recovering energy.

Description

Technical Field

[0001] The utility model relates to the technical field of organic chemical industry, in particular to a high-pressure liquid phase decompression energy recovery system for a urea device. Background Art

[0002] With the development of turbine power generation technology, its application in the field of energy recovery is becoming more and more extensive. The original pure component turbine technology has gradually expanded to the field of materials with two-phase flow under reduced pressure. The working principle of the hydraulic turbine is to use the kinetic energy of high-speed fluid to drive the rotor to rotate, thereby generating mechanical work, which is transmitted to the power generation device to convert mechanical energy into electrical energy.

[0003] In the past few years, some enterprises have discussed the energy recovery of the high-pressure liquid phase of the urea plant entering the medium-pressure system to reduce the pressure, but the various professional technologies involved were not advanced enough and could not be further developed. Figure 1 As shown in the figure, the schematic diagram of the high-pressure system and medium-pressure system of the existing urea device is that the pressure of the high-pressure system of the urea device is about 14.5MPaG and the pressure of the medium-pressure system is about 2.0MPaG. The material of the high-pressure stripper enters the medium-pressure system directly after decompression, which obviously causes energy loss. If this part of energy is recovered for turbine power generation, because the liquid phase of the high-pressure stripper enters the medium pressure after decompression, the gas-liquid two-phase flow after the pressure reduction regulating valve is very difficult to design for the medium of the early hydraulic turbine. In addition, the liquid level control of the high-pressure stripper is a difficult point. The liquid level is only half the volume of the lower pipe box and the head of the high-pressure stripper, so the fluctuation of the liquid level will cause the fluctuation of the liquid output, which is inconsistent with the need for a stable flow rate of the hydraulic turbine. Due to the existence of the above problems, there has been no recovery system in the industry that can make good use of the energy of the high-pressure stripper. With the continuous improvement of technology, the current hydraulic turbine can already meet the medium with gas-liquid two-phase flow, which provides an opportunity for the application of high-pressure strippers in hydraulic turbine power generation devices. Utility Model Content

[0004] The technical problem to be solved by the present application is to provide a high-pressure liquid phase decompression energy recovery system for a urea device, in which a high-pressure accumulator is arranged to ensure the stable operation of a turbine power generation device and a medium-pressure decomposition tower while recovering energy.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is: a high-pressure liquid phase decompression energy recovery system for a urea device, mainly comprising a high-pressure stripping tower 1, a high-pressure accumulator 2, a hydraulic turbine power generation device 3 and a medium-pressure decomposition tower 4, wherein the high-pressure stripping tower 1, the high-pressure accumulator 2, the hydraulic turbine power generation device 3 and the medium-pressure decomposition tower 4 are roughly in a series relationship, and functional valves are arranged between the devices to participate in interlocking and regulation.

[0006] Further, the high-pressure stripping tower 1 is connected to the high-pressure accumulator 2 through the first liquid phase pipeline LP1, the high-pressure accumulator 2 is connected to the hydraulic turbine power generation device 3 through the second liquid phase pipeline LP2, and the hydraulic turbine power generation device 3 is connected to the medium-pressure decomposition tower 4 through the first gas-liquid two-phase pipeline GLP1. The high-pressure accumulator 2 is also connected to the medium-pressure decomposition tower 4 through the third liquid phase pipeline LP3. The first liquid phase pipeline LP1 is provided with a first two-position valve XV1002 and a first pressure reducing regulating valve HV1002; the second liquid phase pipeline LP2 is provided with a second two-position valve XV1004 and a first liquid level pressure reducing regulating valve LICA1001A; the first gas-liquid two-phase pipeline GLP1 is provided with a third two-position valve XV1005 and a second pressure reducing regulating valve HV1005; the third liquid phase pipeline LP3 is provided with a fourth two-position valve XV1003 and a second liquid level pressure reducing regulating valve LICA1002. The high-pressure stripping tower is also provided with a fourth liquid phase pipeline LP4 connected to the medium-pressure decomposition tower. The fourth liquid phase pipeline LP4 is provided with a fifth two-position valve XV1001 and a third liquid level pressure reducing regulating valve LICA1001. The gas phase outlet of the high-pressure accumulator is connected to the gas phase outlet of the high-pressure stripping tower through the first gas phase pipeline GP1, and the first gas phase pipeline GP1 is provided with a third pressure reducing regulating valve HV1006. The high-pressure stripping tower also has a carbon dioxide inlet pipeline. The first liquid level pressure reducing regulating valve LICA1001A of the second liquid phase pipeline LP2 automatically adjusts the third liquid level pressure reducing regulating valve LICA1001 to control the liquid level of the high-pressure stripping tower 1. The second liquid level pressure reducing regulating valve LICA1002 of the third liquid phase pipeline LP3 automatically adjusts the second liquid level pressure reducing regulating valve LICA1002 to control the liquid level of the high-pressure accumulator 2.

[0007] The beneficial effects of the utility model are as follows: the system of the utility model solves the harm to the hydraulic turbine power generation device caused by the unstable material flow due to the small liquid phase space of the high-pressure stripping tower by adding a high-pressure accumulator, and avoids the risk of high pressure series low pressure caused by the liquid level fluctuation of the high-pressure stripping tower. The high-pressure accumulator of the utility model completes the stable flow of the hydraulic turbine device, and the hydraulic turbine power generation device is put into use after the load of the device is stable, which effectively solves the risk of high pressure series low pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The present invention is a schematic diagram of the device flow from the urea high-pressure system to the medium-pressure system in the prior art.

[0009] Figure 2 The present invention is a schematic diagram of a high-pressure liquid phase decompression energy recovery system for a urea device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0010] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The structures, proportions, sizes, etc. illustrated in the accompanying drawings are only used to match the contents disclosed in the specification so that people familiar with the technology can understand and read them. They are not used to limit the limiting conditions that the present invention can implement, so they do not have substantial technical significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects that the present invention can produce and the purposes that can be achieved. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" quoted in this specification are only for the convenience of narration, and are not used to limit the scope that the present invention can implement. The change or adjustment of the relative relationship should also be regarded as the scope that the present invention can implement without substantially changing the technical content.

[0011] Example 1

[0012] See also Figure 2 As shown, it is a schematic diagram of a high-pressure liquid phase decompression energy recovery system of a urea device according to an embodiment of the utility model, which mainly includes a high-pressure stripping tower 1, a high-pressure accumulator 2, a hydraulic turbine power generation device 3 and a medium-pressure decomposition tower 4. The high-pressure stripping tower, the high-pressure accumulator, the hydraulic turbine power generation device and the medium-pressure decomposition tower are roughly in series, and XV and HV valves are arranged between the devices to participate in interlocking and regulation.

[0013] Specifically, the upstream of the system is the same as the prior art. The synthetic reaction liquid from the urea synthesis tower flows into the upper part of the stripping tower 1 by using the potential difference, and then is evenly distributed to each stripping tube in the stripping tower 1 through the liquid distributor in the tower, and falls along the tube wall in the form of a liquid film. The high-pressure CO2 gas from the carbon dioxide compressor is sent to the lower pipe box of the stripping tower through the control of the regulating valve, and meets the synthetic reaction liquid from the synthesis tower in the tube array in the countercurrent. The tubes are heated by steam from the high-pressure drum. The excess ammonia and unconverted methylammonium liquid in the synthetic reaction liquid will be stripped and decomposed, and discharged from the top of the stripping tower and sent to the full condensation reactor. Among them, the operating pressure of the stripping tower is 13.5-14.8MPaA, and the outlet liquid temperature is controlled between 165 and 175℃; the liquid level at the bottom of the tower is controlled at about 220mm; the medium-pressure decomposition pressure is 1.8-2.2MPaA.

[0014] In order to reasonably, effectively and safely utilize the energy of the liquid phase of the stripping tower in the present application, a high-pressure accumulator 2 is arranged after the high-pressure stripping tower 1 in the original system. The high-pressure stripping tower 1 is connected to the high-pressure accumulator 2 by setting a first two-position valve XV1002 and a first pressure reducing regulating valve HV1002 through the first liquid phase pipeline LP1, and the high-pressure accumulator 2 is connected to the hydraulic turbine power generation device 3 by setting a second two-position valve XV1004 and a first liquid level pressure reducing regulating valve LICA1001A through the second liquid phase pipeline LP2, and the hydraulic turbine power generation device 3 is connected to the medium-pressure decomposition tower 4 by setting a third two-position valve XV1005 and a second pressure reducing regulating valve HV1005 through the first gas-liquid two-phase pipeline GLP1. The high-pressure accumulator 2 is also connected to the medium-pressure decomposition tower 4 by setting a fourth two-position valve XV1003 and a second liquid level pressure reducing regulating valve LICA1002 through the third liquid phase pipeline LP3. The first liquid level pressure reducing regulating valve LICA1001A of the second liquid phase pipeline LP2 automatically regulates the third liquid level pressure reducing regulating valve LICA1001 to control the liquid level of the high pressure stripping tower 1. The second liquid level pressure reducing regulating valve LICA1002 of the third liquid phase pipeline LP3 automatically regulates the second liquid level pressure reducing regulating valve LICA1002 to control the liquid level of the high pressure accumulator 2.

[0015] The specific process flow of the above system includes the following steps:

[0016] S1: When the urea unit is started up for production and addition, the liquid phase of the high-pressure stripping tower enters the high-pressure accumulator through the first liquid phase pipeline LP1, the first two-position valve XV1002 and the first pressure reducing regulating valve HV1002, and the gas phase of the high-pressure accumulator is connected to the gas phase of the high-pressure stripping tower through the third pressure reducing regulating valve HV1006 provided on the first gas phase pipeline GP1.

[0017] S2: Open the third two-position valve XV1005 of the third liquid phase pipeline LP3, and the second liquid level pressure reducing regulating valve LICA1002 controls the liquid level stability of the high-pressure accumulator

[0018] S3: Control the opening of the first pressure reducing regulating valve HV1002 to keep the liquid level of the high-pressure stripping tower stable, and keep the liquid level of the high-pressure accumulator stable through the second liquid level pressure reducing regulating valve LICA1002.

[0019] S4: After waiting for the liquid level of the high-pressure stripping tower 1 and the liquid level of the high-pressure accumulator 2 to stabilize, open the first two-position valve XV1004, manually open the first liquid level pressure reducing regulating valve LICA1001A, close the second liquid level pressure reducing regulating valve LICA1002, and control the liquid level of the high-pressure stripping tower 1 to be stable through the first liquid level pressure reducing regulating valve LICA1001A, and keep the first pressure reducing regulating valve HV1002 at a certain opening, so that the high-pressure accumulator is in a stable liquid state.

[0020] S4: Keep the first liquid level pressure reducing regulating valve LICA1001A open to allow high-pressure liquid to enter the hydraulic turbine power generation device 3 until the load is stable and the hydraulic turbine power generation device operates normally.

[0021] S5: Gradually close the second liquid level pressure reducing regulating valve LICA1002 until it is closed, that is, close the third liquid phase pipeline.

[0022] S6: The gas-liquid two-phase fluid passing through the hydraulic turbine power generation device enters the medium-pressure system through the first gas-liquid two-phase pipeline GLP1.

[0023] Further reading Figure 2 The high-pressure stripping tower is also provided with a fourth liquid phase pipeline LP4, a fifth two-position valve XV1001 and a third liquid level pressure reducing regulating valve LICA1001, which are directly connected to the medium-pressure decomposition tower. If the load fluctuates or the hydraulic turbine power generation fails, because the liquid level control of the stripping tower still needs the liquid level pressure reducing regulating valve of the medium-pressure pipeline under the stripping tower to control the liquid level, at this time, the first liquid phase pipeline LP1 is cut off and the LP4 pipeline is connected.

[0024] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-pressure liquid phase decompression energy recovery system for a urea device, characterized in that: The invention mainly comprises a high-pressure stripping tower (1), a high-pressure accumulator (2), a hydraulic turbine power generation device (3) and a medium-pressure decomposition tower (4), wherein the high-pressure stripping tower (1), the high-pressure accumulator (2), the hydraulic turbine power generation device (3) and the medium-pressure decomposition tower (4) are connected in series, and functional valves are arranged between the devices to participate in interlocking and regulation.

2. The urea device high pressure liquid phase decompression energy recovery system according to claim 1, characterized in that: The high-pressure stripping tower (1) is connected to the high-pressure accumulator (2) via a first liquid phase pipeline (LP1), the high-pressure accumulator (2) is connected to a hydraulic turbine power generation device (3) via a second liquid phase pipeline (LP2), and the hydraulic turbine power generation device (3) is connected to a medium-pressure decomposition tower (4) via a first gas-liquid two-phase pipeline (GLP1).

3. The urea device high pressure liquid phase decompression energy recovery system according to claim 2, characterized in that: The high-pressure accumulator (2) is also connected to the medium-pressure decomposition tower (4) via a third liquid phase pipeline (LP3).

4. The urea device high pressure liquid phase decompression energy recovery system according to claim 3, characterized in that: The first liquid phase pipeline (LP1) is provided with a first two-position valve (XV1002) and a first pressure reducing regulating valve (HV1002); The second liquid phase pipeline (LP2) is provided with a second two-position valve (XV1004) and a first liquid level pressure reducing regulating valve (LICA1001A); The first gas-liquid two-phase pipeline (GLP1) is provided with a third two-position valve (XV1005) and a second pressure reducing regulating valve (HV1005); The third liquid phase pipeline (LP3) is provided with a fourth two-position valve (XV1003) and a second liquid level pressure reducing regulating valve (LICA1002).

5. The urea device high pressure liquid phase decompression energy recovery system according to claim 3, characterized in that: The high-pressure stripping tower is also provided with a fourth liquid phase pipeline (LP4) connected to the medium-pressure decomposition tower.

6. The urea device high pressure liquid phase decompression energy recovery system according to claim 5, characterized in that: The fourth liquid phase pipeline (LP4) is provided with a fifth two-position valve (XV1001) and a third liquid level pressure reducing regulating valve (LICA1001).

7. The urea device high pressure liquid phase decompression energy recovery system according to claim 2, characterized in that: The gas phase outlet of the high-pressure accumulator is connected to the gas phase outlet of the high-pressure stripping tower through a first gas phase pipeline (GP1), and the first gas phase pipeline (GP1) is provided with a third pressure reducing regulating valve (HV1006).

8. The urea device high pressure liquid phase decompression energy recovery system according to claim 2, characterized in that: The high-pressure stripping column also has a carbon dioxide inlet pipeline.

9. The urea device high pressure liquid phase decompression energy recovery system according to claim 2, characterized in that: The first liquid level pressure reducing regulating valve (LICA1001A) of the second liquid phase pipeline (LP2) automatically regulates the third liquid level pressure reducing regulating valve (LICA1001) to control the liquid level of the high-pressure stripping tower (1).

10. The urea device high pressure liquid phase decompression energy recovery system according to claim 2, characterized in that: The second liquid level pressure reducing regulating valve (LICA1002) of the third liquid phase pipeline (LP3) automatically regulates the second liquid level pressure reducing regulating valve (LICA1002) to control the liquid level of the high-pressure accumulator (2).

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