Urea low-pressure steam recovery device

Abstract

The utility model provides a urea low-pressure steam recovery device, which belongs to the technical field of chemical engineering and structurally comprises a urea production device, a steam turbine and a deaerator. A urea production device outputs a byproduct 0.35 MPa steam header pipe, and on the basis that the byproduct 0.35 MPa steam header pipe is connected with a 0.35 MPa steam blow-down pipe, the byproduct 0.35 MPa steam header pipe at least outputs two branches in parallel, namely a steam turbine steam injection 0.35 MPa steam inlet pipe and a deaerator 0.35 MPa steam inlet pipe; the downstream of the steam turbine steam injection 0.35 MPa steam inlet pipe is converged and communicated to the steam turbine steam injection 0.5 MPa steam inlet pipe, and the downstream end of the steam turbine steam injection 0.5 MPa steam inlet pipe is communicated to the steam turbine; the downstream of the 0.35 MPa steam inlet pipe of the deaerator is converged and communicated to the 0.5 MPa steam inlet pipe of the deaerator; and the downstream end of the 0.5 MPa steam inlet pipe of the deaerator is communicated to the deaerator. All pipeline valves are controlled through process interlocking, and by-product low-pressure steam is conveyed to a deaerator and a steam turbine to replace medium-pressure steam, so that energy waste is effectively avoided, the emptying amount is reduced, and energy conservation and consumption reduction are achieved.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, specifically a urea low-pressure steam recovery device. Background Technology

[0002] In typical CO2 stripping urea production processes, the urea unit produces a portion of 0.35 MPa low-pressure steam as a byproduct. However, in synthetic ammonia urea processes, to meet various production requirements, five pressure levels of piping networks are generally configured: 9.8 MPa, 3.8 MPa, 2.5 MPa, 1.5 MPa, and 0.5 MPa. Therefore, the 0.35 MPa low-pressure steam produced by the urea unit cannot be effectively recovered into the steam network due to its low pressure and is generally vented directly, resulting in energy waste. Furthermore, in synthetic ammonia urea production processes, the low-pressure deaerator and turbine steam injection typically require 0.5 MPa steam. The 0.35 MPa low-pressure steam produced by the urea unit cannot be directly utilized either. Summary of the Invention

[0003] The technical objective of this invention is to address the shortcomings of existing technologies and provide a urea low-pressure steam recovery device.

[0004] The technical solution of this utility model is implemented in the following way: a urea low-pressure steam recovery device of this utility model, the structure of which includes a urea production device (1), a steam turbine (2) and a deaerator (3).

[0005] The urea production unit (1) outputs a 0.35MPa steam main (6) as a byproduct. Based on the connection of the 0.35MPa steam main (6) to the 0.35MPa steam vent pipe (10), the 0.35MPa steam main (6) also outputs at least two branch lines in parallel, namely the 0.35MPa steam inlet pipe (8) for turbine injection and the 0.35MPa steam inlet pipe (9) for deaerator.

[0006] The downstream confluence of the 0.35MPa steam inlet pipe (8) for turbine steam injection is connected to the 0.5MPa steam inlet pipe (11) for turbine steam injection. The confluence of the two pipes is located upstream of the confluence node.

[0007] The steam turbine injection 0.35MPa steam inlet pipe (8) is equipped with a steam turbine auxiliary steam injection valve (18).

[0008] The steam turbine main line steam injection valve (17) is installed in the steam turbine injection 0.5MPa steam inlet pipe (11).

[0009] The downstream end of the 0.5MPa steam inlet pipe (11) for steam turbine injection is connected to the steam inlet end of the steam turbine (2);

[0010] The downstream confluence of the 0.35MPa steam inlet pipe (9) of the deaerator is connected to the 0.5MPa steam inlet pipe (12) of the deaerator, at the upstream position of the confluence node of the two:

[0011] A deaerator auxiliary steam injection valve (20) is installed on the 0.35MPa steam inlet pipe (9) of the deaerator.

[0012] A deaerator main steam injection valve (19) is installed on the 0.5MPa steam inlet pipe (12) of the deaerator.

[0013] The downstream end of the 0.5MPa steam inlet pipe (12) of the deaerator is connected to the deaerator (3).

[0014] The by-product 0.35MPa steam main pipe (6) also has a branch output in parallel: 0.35MPa steam recovery and utilization pipe (7), which is connected to the upstream of the urea production unit (1) as a supplement to the low-pressure return flow and supply to the upstream of the urea production unit.

[0015] A venting control valve (21) is installed on the 0.35MPa steam venting pipe (10).

[0016] The vent control valve (21) is set as a normally closed vent control valve.

[0017] A silencer (5) is connected to the downstream end of the 0.35MPa steam vent pipe (10) where the vent control valve (21) is located.

[0018] The deaerator (3) is equipped with a deaerator inlet pipe (13) and a deaerator outlet pipe (14).

[0019] The bottom of the urea production unit (1) is connected to the inlet pipe (15) of the steam condensate tank, and the downstream of the inlet pipe (15) of the steam condensate tank is connected to the steam condensate tank (4). The bottom of the steam condensate tank (4) is connected to the outlet pipe (16).

[0020] A level gauge (22) is installed on the steam condensate tank (4).

[0021] Both the main turbine steam injection valve (17) and the auxiliary turbine steam injection valve (18) are solenoid valves, and they are electrically interlocked.

[0022] When the main steam injection valve (17) of the steam turbine is opened, the auxiliary steam injection valve (18) of the steam turbine is closed;

[0023] When the auxiliary steam injection valve (18) of the steam turbine is opened, the main steam injection valve (17) of the steam turbine is closed.

[0024] Both the main deaerator steam injection valve (19) and the auxiliary deaerator steam injection valve (20) are solenoid valves, and they are electrically interlocked.

[0025] When the main deaerator steam injection valve (19) is opened, the auxiliary deaerator steam injection valve (20) is closed;

[0026] When the deaerator auxiliary steam injection valve (20) is opened, the deaerator main steam injection valve (19) is closed.

[0027] The beneficial effects of this utility model compared with the prior art are:

[0028] This utility model discloses a urea low-pressure steam recovery device, which sends the 0.35 MPa low-pressure steam produced by the urea plant to the deaerator and steam turbine to replace the 0.5 MPa steam, effectively avoiding energy waste and saving energy.

[0029] The low-grade heat energy of 0.35MPa is effectively utilized, reducing the amount of venting and saving energy.

[0030] This reduced the output of 0.5MPa steam injected into the deaerator and turbine, thus increasing economic benefits.

[0031] Specifically:

[0032] The valves are controlled via process interlocks. One route of the 0.35MPa low-pressure steam produced as a byproduct of the urea plant returns to the urea plant, providing heat to maintain normal production in its heaters; this steam is consumed within the plant itself. Excess 0.35MPa low-pressure steam not consumed during urea plant production is sent to the deaerator, replacing 0.5MPa steam as the heat source for deaeration; a portion also enters the final stage of the turbine as steam injection. This not only effectively recovers the 0.35MPa low-pressure steam but also reduces the amount of 0.5MPa steam used in the ammonia-urea synthesis process. This results in energy savings, reduced consumption, and increased profits.

[0033] The urea low-pressure vapor recovery device of this utility model is reasonably designed, simple in structure, safe and reliable, easy to use and maintain, and has great value for promotion and application. Attached Figure Description

[0034] Appendix Figure 1 This is a schematic diagram of the structural process of this utility model.

[0035] The markings in the attached diagram represent:

[0036] 1. Urea production unit; 2. Steam turbine; 3. Deaerator; 4. Steam condensate tank; 5. Silencer; 6. By-product 0.35MPa steam main; 7. 0.35MPa steam recovery pipe; 8. Steam turbine injection 0.35MPa steam inlet pipe; 9. Deaerator 0.35MPa steam inlet pipe; 10. 0.35MPa steam vent pipe; 11. Steam turbine injection 0.5MPa steam inlet pipe; 12. Deaerator 0.5MPa steam inlet pipe; 13. Deaerator water inlet pipe; 14. Deaerator water outlet pipe; 15. Steam condensate tank inlet pipe; 16. Steam condensate tank outlet pipe;

[0037] 17. Steam injection valve for main turbine circuit; 18. Steam injection valve for auxiliary turbine circuit; 19. Steam injection valve for main deaerator circuit; 20. Steam injection valve for auxiliary deaerator circuit; 21. Vent control valve; 22. Level gauge. Detailed Implementation

[0038] The following is a detailed description of a urea low-pressure steam recovery device according to the present invention, with reference to the accompanying drawings.

[0039] As shown in the attached figure, the urea low-pressure steam recovery device of this utility model includes the following structure: urea unit, steam turbine, deaerator, steam condensate tank, and silencer.

[0040] The inlet of urea production unit 1 is connected to a 0.35MPa steam recovery pipe, and the outlet is connected to a 0.35MPa steam main pipe and a steam condensate tank inlet pipe. During normal production, the low-pressure steam drum and medium-pressure steam drum equipment in the urea production unit will produce 0.35MPa low-pressure steam as a byproduct. This byproduct 0.35MPa low-pressure steam is output through the 0.35MPa steam main pipe 6. One path returns to the urea unit through the 0.35MPa steam recovery pipe 7, serving as a heat source for the medium-pressure heater, low-pressure heater, and evaporator heater in the urea unit, and is consumed and utilized within the urea unit itself. After providing a heat source for the equipment, the 0.35MPa low-pressure steam cools down and becomes steam condensate, which enters the steam condensate tank 4 through the steam condensate tank inlet pipe 15 for storage and recycling.

[0041] The inlet of turbine 2 is connected to the 0.5MPa steam inlet pipe 11. During normal production, the steam pressure of the last stage of the turbine is around 0.35MPa. In order to reduce the amount of medium-pressure steam used at the turbine inlet, low-pressure steam is generally injected into the turbine at the last stage through the 0.5MPa steam inlet pipe 11, thereby reducing the amount of medium-pressure steam used at the turbine inlet and achieving the purpose of energy saving and consumption reduction.

[0042] The inlet of deaerator 3 is connected to the 0.5MPa steam inlet pipe 12 and the deoxygenated water inlet pipe 13, and the outlet is connected to the deoxygenated water outlet pipe 14. Deoxygenated water enters the deaerator through the deoxygenated water inlet pipe 13 and undergoes thermal deoxygenation under the action of low-pressure steam. After removing dissolved oxygen from the water, it is sent to the external water-using unit through the deoxygenated water outlet pipe 14. Low-pressure steam enters the deaerator through the 0.5MPa steam inlet pipe 12, providing a heat source for the deoxygenation operation.

[0043] The inlet end of the steam condensate tank 4 is connected to the steam condensate tank inlet pipe 15, and the outlet end is connected to the steam condensate tank outlet pipe 16. After the 0.35MPa low-pressure steam provides a heat source for the various energy-consuming equipment in the urea plant, its own temperature decreases, and it becomes steam condensate. It enters the steam condensate tank 4 through the steam condensate tank inlet pipe 15 for storage, and then is sent to the external water unit for recycling through the steam condensate tank outlet pipe 16.

[0044] The inlet of the silencer 5 is connected to the 0.35MPa steam vent pipe 10, and the outlet is connected to the atmosphere. In abnormal circumstances, 0.35MPa low-pressure steam can be directly vented through the 0.35MPa steam vent pipe 10. When venting 0.35MPa low-pressure steam, it first enters the silencer 5 through the 0.35MPa steam vent pipe 10. The silencer 5 reduces the noise during steam venting and avoids environmental noise pollution.

[0045] Thus, the 0.35MPa steam main 6 is divided into four branches: the 0.35MPa steam recovery and utilization pipe 7, the 0.35MPa steam inlet pipe for turbine steam injection 8, the 0.35MPa steam inlet pipe for deaerator 9, and the 0.35MPa steam vent pipe 10.

[0046] Furthermore, the 0.5MPa steam inlet pipe 11 for turbine injection is connected to the 0.35MPa steam inlet pipe 8 for turbine injection. The excess 0.35MPa low-pressure steam produced as a byproduct of the urea system is incorporated into the 0.5MPa steam inlet pipe 11 for turbine injection through the 0.35MPa steam inlet pipe 8 for turbine injection, and then enters the final stage of turbine 2 through the 0.5MPa steam inlet pipe 11 for turbine injection.

[0047] Furthermore, the 0.5MPa steam inlet pipe 12 of the deaerator is connected to the 0.35MPa steam inlet pipe 9 of the deaerator. The excess 0.35MPa low-pressure steam produced as a byproduct of the urea system is incorporated into the 0.5MPa steam inlet pipe 12 of the deaerator through the 0.35MPa steam inlet pipe 9 of the deaerator, and then enters the deaerator 9 through the 0.5MPa steam inlet pipe 12 of the deaerator.

[0048] Furthermore, a main steam injection valve 17 is installed on the 0.5MPa steam inlet pipe 11, and a secondary steam injection valve 18 is installed on the 0.35MPa steam inlet pipe 8. When there is an excess of 0.35MPa low-pressure steam produced as a byproduct of the urea system, the main steam injection valve 17 can be closed and the secondary steam injection valve 18 can be opened. At this time, the steam injection of turbine 2 uses the excess 0.35MPa low-pressure steam produced as a byproduct of the urea system, and the original 0.5MPa steam pipeline is disconnected, saving the consumption of 0.5MPa steam. The saved 0.5MPa steam can be sold or used for power generation, increasing economic benefits.

[0049] Furthermore, a main steam injection valve 19 is installed on the 0.5MPa steam inlet pipe 12 of the deaerator, and a secondary steam injection valve 20 is installed on the 0.35MPa steam inlet pipe 9 of the deaerator. When there is an excess of 0.35MPa low-pressure steam produced as a byproduct of the urea system, the main steam injection valve 19 can be closed and the secondary steam injection valve 20 can be opened. At this time, the deaerator 3 uses the excess 0.35MPa low-pressure steam produced as a byproduct of the urea system for thermal deoxygenation, and the original 0.5MPa steam pipeline is disconnected, saving the consumption of 0.5MPa steam. The saved 0.5MPa steam can be sold externally or used for power generation, increasing economic benefits.

[0050] Furthermore, a venting control valve 21 is installed on the 0.35MPa steam venting pipe 10. When the turbine 2 or deaerator 3 malfunctions, or when the turbine 2 or deaerator 3 does not require 0.35MPa low-pressure steam, the turbine auxiliary steam injection valve 18 and the deaerator auxiliary steam injection valve 20 can be closed, and the venting control valve 21 can be opened. At this time, the excess 0.35MPa low-pressure steam produced as a byproduct of the urea unit can be directly vented through the 0.35MPa steam venting pipe 10.

[0051] Furthermore, a level gauge 22 is installed on the steam condensate tank 4 to monitor the level of steam condensate in the steam condensate tank 4 and maintain the stability of the externally supplied steam condensate.

Claims

1. A urea low-pressure vapor recovery device, characterized in that... It includes a urea production unit (1), a steam turbine (2), and a deaerator (3); The urea production unit (1) outputs a 0.35MPa steam main (6) as a byproduct. Based on the connection of the 0.35MPa steam main (6) to the 0.35MPa steam vent pipe (10), the 0.35MPa steam main (6) also outputs at least two branch lines in parallel, namely the 0.35MPa steam inlet pipe (8) for turbine injection and the 0.35MPa steam inlet pipe (9) for deaerator. The downstream confluence of the 0.35MPa steam inlet pipe (8) for turbine steam injection is connected to the 0.5MPa steam inlet pipe (11) for turbine steam injection. The confluence of the two pipes is located upstream of the confluence node. The steam turbine injection 0.35MPa steam inlet pipe (8) is equipped with a steam turbine auxiliary steam injection valve (18). The steam turbine main line steam injection valve (17) is installed in the steam turbine injection 0.5MPa steam inlet pipe (11). The downstream end of the 0.5MPa steam inlet pipe (11) for steam turbine injection is connected to the steam inlet end of the steam turbine (2); The downstream confluence of the 0.35MPa steam inlet pipe (9) of the deaerator is connected to the 0.5MPa steam inlet pipe (12) of the deaerator, at the upstream position of the confluence node of the two: A deaerator auxiliary steam injection valve (20) is installed on the 0.35MPa steam inlet pipe (9) of the deaerator. A deaerator main steam injection valve (19) is installed on the 0.5MPa steam inlet pipe (12) of the deaerator. The downstream end of the 0.5MPa steam inlet pipe (12) of the deaerator is connected to the deaerator (3).

2. The urea low-pressure vapor recovery device according to claim 1, characterized in that: The by-product 0.35MPa steam main pipe (6) also has a branch output in parallel: 0.35MPa steam recovery and utilization pipe (7), which is connected to the upstream of the urea production unit (1) as a supplement to the low-pressure return flow and supply to the upstream of the urea production unit.

3. The urea low-pressure vapor recovery device according to claim 1, characterized in that: A venting control valve (21) is installed on the 0.35MPa steam venting pipe (10).

4. The urea low-pressure vapor recovery device according to claim 1, characterized in that: The vent control valve (21) is set as a normally closed vent control valve.

5. The urea low-pressure vapor recovery device according to claim 1, characterized in that: A silencer (5) is connected to the downstream end of the 0.35MPa steam vent pipe (10) where the vent control valve (21) is located.

6. The urea low-pressure vapor recovery device according to claim 1, characterized in that: The deaerator (3) is equipped with a deaerator inlet pipe (13) and a deaerator outlet pipe (14).

7. The urea low-pressure vapor recovery device according to claim 1, characterized in that: The bottom of the urea production unit (1) is connected to the inlet pipe (15) of the steam condensate tank, and the downstream of the inlet pipe (15) of the steam condensate tank is connected to the steam condensate tank (4). The bottom of the steam condensate tank (4) is connected to the outlet pipe (16).

8. A urea low-pressure vapor recovery device according to claim 5, characterized in that: A level gauge (22) is installed on the steam condensate tank (4).

9. A urea low-pressure vapor recovery device according to claim 1, characterized in that: Both the main turbine steam injection valve (17) and the auxiliary turbine steam injection valve (18) are solenoid valves, and they are electrically interlocked. When the main steam injection valve (17) of the steam turbine is opened, the auxiliary steam injection valve (18) of the steam turbine is closed; When the auxiliary steam injection valve (18) of the steam turbine is opened, the main steam injection valve (17) of the steam turbine is closed.

10. A urea low-pressure vapor recovery device according to claim 1, characterized in that: Both the main deaerator steam injection valve (19) and the auxiliary deaerator steam injection valve (20) are solenoid valves, and they are electrically interlocked. When the main deaerator steam injection valve (19) is opened, the auxiliary deaerator steam injection valve (20) is closed; When the deaerator auxiliary steam injection valve (20) is opened, the deaerator main steam injection valve (19) is closed.

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