System for recovering waste heat of urea hydrolysis drainage
By introducing a hydrophobic circulation pump and heat exchange coil into the urea hydrolysis system, the recovery of hydrophobic waste heat and the heating of urea solution are achieved, the problems of high hydrophobic temperature and large desalination water consumption are solved, and the energy-saving and water-saving effect is achieved.
Patent Information
- Application Number
- CN202420015624.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-04
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-01-04
AI Technical Summary
The hydrophobic waste heat in the existing urea hydrolysis system is not fully utilized, resulting in high hydrophobic temperature and easy to cause scald accidents. The consumption of desalination water for cooling is large and the economy is poor.
Design a system including a saturated steam inlet, a urea hydrolysis reactor, a hydrophobic device, a hydrophobic circulation pump and a urea solution storage device, and use a hydrophobic circulation pump to transport the hydrophobic coils in the urea solution storage device for indirect heat exchange. Recycle waste heat from drainage, and switch between steam heating and automatic shutoff valve and automatic shutoff valve for optimizing heat utilization.
Reducing the hydrophobic temperature in the hydrophobic device to 70℃-76℃ reduces the desalination water consumption, saves heat tracing steam consumption, increases the storage temperature of the urea solution, and significantly saves energy consumption and water resources.
Smart Images
Figure CN222143804U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of urea hydrolysis, in particular to a system for recovering hydrophobic waste heat from urea hydrolysis. Background Art
[0002] The urea hydrolysis process is one of the mainstream systems for the preparation of SCR flue gas denitrification reducing agents in thermal power plants. The main equipment includes urea dissolving tank, urea solution storage device, hydrophobic device, urea hydrolysis reactor, and steam temperature and pressure reduction device. The process flow is to use the hydrophobic or desalted water in the hydrophobic device to dissolve urea granules in the urea dissolving tank to prepare a urea solution of about 50%wt, transport it to the urea solution storage device for storage, and transport it to the urea hydrolysis reactor through a pump to hydrolyze it into a mixed gas of NH3, CO2 and H2O. During the hydrolysis reaction, saturated steam of about 0.9MPa and 175℃ is required to enter the hydrolysis reactor through the heat exchange coil to heat the urea solution. The steam hydrophobic after heat exchange is returned to the hydrophobic device through the steam trap and pipeline for recovery. The hydrophobic temperature in the hydrophobic device is generally 90-100℃, the residual heat of the hydrophobic device is not fully utilized, and the hydrophobic temperature is high. A large amount of water vapor escapes from the vents on the top of the hydrophobic device, which is easy to cause scalding accidents. In actual projects, the most commonly used measure is to add deionized water to the drain device for cooling. However, the amount of drain produced in the urea hydrolysis system is much greater than the amount of water required to dissolve urea, and the method of adding deionized water for cooling is less economical. Therefore, it is necessary to develop a system that can reasonably utilize the waste heat of drain in the urea hydrolysis system. Utility Model Content
[0003] In order to overcome the deficiencies of the prior art, the utility model provides a system for recovering waste heat from urea hydrolysis, which solves the problems of large consumption of desalted water for cooling and heating steam consumption in the prior art.
[0004] The technical solution adopted by the utility model to solve the above problems is:
[0005] A system for recovering waste heat from urea hydrolysis hydrophobicity includes a saturated steam inlet, a urea hydrolysis reactor, a hydrophobicity device, a hydrophobicity circulation pump, and a urea solution storage device which are connected in sequence, and also includes a heating device arranged in the urea solution storage device.
[0006] As a preferred technical solution, it also includes a plant auxiliary steam inlet connected to the urea solution storage device.
[0007] As a preferred technical solution, it also includes a steam heating automatic shut-off valve arranged on the connecting pipeline between the auxiliary steam inlet of the plant area and the urea solution storage device.
[0008] As a preferred technical solution, it also includes a hydrophobic heating automatic shut-off valve arranged on the connecting pipeline between the hydrophobic circulation pump and the urea solution storage device.
[0009] As a preferred technical solution, it also includes a steam trap group, and the steam trap device, the steam trap group, and the urea solution storage device are connected in sequence.
[0010] As a preferred technical solution, it also includes a liquid level meter arranged on the hydrophobic device.
[0011] As a preferred technical solution, it also includes a hydrophobic device temperature measuring point arranged on the hydrophobic device.
[0012] As a preferred technical solution, it also includes a storage device temperature measuring point arranged on the urea solution storage device.
[0013] As a preferred technical solution, the urea solution storage device is a urea solution storage tank.
[0014] As a preferred technical solution, the heating device is a heat exchange coil.
[0015] Compared with the prior art, the utility model has the following beneficial effects:
[0016] The utility model can reduce the drain temperature in the drain device to 70°C-76°C, reducing the consumption of desalted water for cooling; at the same time, the waste heat of the drain is used to heat the urea solution in the storage tank, saving the consumption of heating steam. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a structural schematic diagram of the utility model.
[0018] Marks and their corresponding names in the attached drawings: 1. urea hydrolysis reactor, 2. drain device, 21. drain device temperature measuring point, 22. liquid level gauge, 3. drain circulation pump, 4. urea solution storage device, 41. heating device, 5. drain valve group, 6. steam heating automatic shut-off valve, 7. drain heating automatic shut-off valve, 8. storage device temperature measuring point, 9. saturated steam inlet, 10. plant auxiliary steam inlet. DETAILED DESCRIPTION
[0019] The present invention will be further described in detail below in conjunction with the embodiments and drawings, but the implementation manner of the present invention is not limited thereto.
[0020] Example 1
[0021] like Figure 1As shown, a system for recovering waste heat from urea hydrolysis hydrophobicity includes a saturated steam inlet 9, a urea hydrolysis reactor 1, a hydrophobicity device 2, a hydrophobicity circulation pump 3, and a urea solution storage device 4, which are connected in sequence, and also includes a heating device 41 arranged in the urea solution storage device 4.
[0022] As a preferred technical solution, it also includes a plant auxiliary steam inlet 10 connected to the urea solution storage device 4 .
[0023] As a preferred technical solution, it also includes a steam heating automatic shut-off valve 6 arranged on the connecting pipeline between the plant auxiliary steam inlet 10 and the urea solution storage device 4 .
[0024] As a preferred technical solution, it also includes a hydrophobic heating automatic shut-off valve 7 arranged on the connecting pipeline between the hydrophobic circulation pump 3 and the urea solution storage device 4 .
[0025] As a preferred technical solution, it also includes a steam trap group 5, and the steam trap device 2, the steam trap group 5, and the urea solution storage device 4 are connected in sequence.
[0026] As a preferred technical solution, it also includes a liquid level meter 22 arranged on the hydrophobic device 2.
[0027] As a preferred technical solution, it also includes a hydrophobic device temperature measuring point 21 arranged on the hydrophobic device 2.
[0028] As a preferred technical solution, it also includes a storage device temperature measuring point 8 arranged on the urea solution storage device 4.
[0029] As a preferred technical solution, the urea solution storage device 4 is a urea solution storage tank.
[0030] As a preferred technical solution, the heating device 41 is a heat exchange coil.
[0031] Example 2
[0032] like Figure 1 As shown, as a further optimization of Example 1, based on Example 1, this embodiment also includes the following technical features:
[0033] The utility model aims to propose a system that can utilize the residual heat of urea hydrolysis system to increase the temperature of the solution in the urea solution storage device, reduce the temperature of the urea solution in the urea solution storage device, save steam consumption and reduce the consumption of desalted water.
[0034] The drain circulation pump is used to transport the drain in the drain device to the coil in the urea solution storage device, and indirectly circulates heat with the urea solution to recover the drain waste heat, increase the temperature of the solution in the urea solution storage device, and reduce the drain temperature in the drain device.
[0035] The saturated steam after passing through the steam temperature reduction and pressure reduction device enters the urea hydrolysis reactor 1 through the saturated steam inlet 9, and enters the drain device 2 (preferably a drain tank) after heat exchange in the urea hydrolysis reactor 1. The drain is transported to the heating device 41 (preferably a heat exchange coil) in the urea solution storage device 4 through the drain circulation pump 3 to exchange heat with the urea solution, and the heated drain returns to the drain device 2.
[0036] At the initial start-up of the system, the steam heating automatic shut-off valve 6 is opened to allow the plant auxiliary steam to enter the heat exchange coil in the urea solution storage device 4 (preferably the urea solution storage tank) through the plant auxiliary steam inlet 10 to heat the urea solution. When the temperature measuring point 21 of the hydrophobic device is higher than 60°C and the hydrophobic liquid level gauge 22 is higher than the low liquid level, the hydrophobic heating automatic shut-off valve 7 is opened, the steam heating automatic shut-off valve 6 is closed, the hydrophobic circulation pump 3 is started, and the hydrophobic heating is used to heat the urea solution in the urea solution storage device 4.
[0037] During the normal operation phase, when the temperature of the storage device temperature measuring point 8 of the urea solution storage device 4 is found to be lower than 25°C or the drain level gauge 22 in the drain device 2 is at a low level, the drain heating automatic shutoff valve 7 is closed, and the steam heating automatic shutoff valve 6 is opened to allow the plant auxiliary steam to enter the heat exchange coil in the urea solution storage device 4 to heat the urea solution. When the storage device temperature measuring point reaches 30°C, the steam heating automatic shutoff valve 6 is closed, and the drain heating automatic shutoff valve 7 is opened to switch the heat exchange medium to the drain.
[0038] Taking a 2×600MW unit flue gas denitrification project as an example, the ammonia consumption of a single unit for flue gas denitrification is 250kg / h, and the total ammonia consumption of the two units is 500kg / h. The conventional urea hydrolysis system is equipped with two urea solution storage devices, and the total effective volume meets the urea solution consumption of the two units for 7 days. The effective volume of a single urea solution storage device is 131m 3 According to the design of filling coefficient 0.9, the total volume of a single urea solution storage device is 146m 3 , diameter 5.4m, height 6.4m. The operating temperature of the urea solution storage device is 40℃, and the total heat loss of the two urea solution storage devices and the urea solution delivery pipeline is about 21650W. The hydrophobic production is 2000kg / h, the hydrophobic temperature is 95℃, and the hydrophobic device temperature is reduced to 75℃ by adding 20℃ desalted water. The desalted water consumption is 800kg / h.
[0039] After adopting the utility model, a drain pump is set up, and the residual heat of the drain in the drain device is used to heat the urea solution in the storage tank to 55°C. The temperature in the drain device is reduced to 74°C-77°C, and the residual heat of the drain is recovered, which saves 70kg / h of steam consumption and 800kg / h of desalted water consumption, and has obvious water-saving and energy-saving effects. The electric power of the drain pump is 4kW, which has good economic benefits according to the conventional unit price of energy media in domestic power plants.
[0040] In the utility model, the urea solution storage device is provided with a heat exchange coil, which can utilize the residual heat of the hydrophobic to heat the urea solution;
[0041] In the utility model, a hydrophobic circulation pump is provided to utilize the hydrophobicity to heat the urea solution in the storage tank, thereby increasing the operating temperature of the urea solution storage device;
[0042] In the utility model, a switching valve for drain heating and steam heating is provided to ensure the stability of the system.
[0043] The utility model can reduce the drain temperature in the drain device to 70°C-76°C, reducing the consumption of desalted water for cooling; at the same time, the waste heat of the drain is used to heat the urea solution in the storage tank, saving the consumption of heating steam.
[0044] As described above, the utility model can be implemented well.
[0045] The above is only a preferred embodiment of the utility model and does not limit the utility model in any form. According to the technical essence of the utility model, within the spirit and principles of the utility model, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the utility model.
Claims
1. A system for recovering waste heat from urea hydrolysis, characterized in that: The invention comprises a saturated steam inlet (9), a urea hydrolysis reactor (1), a hydrophobic device (2), a hydrophobic circulation pump (3), and a urea solution storage device (4) which are connected in sequence, and also comprises a heating device (41) arranged in the urea solution storage device (4).
2. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a plant auxiliary steam inlet (10) connected to the urea solution storage device (4).
3. A system for recovering waste heat from urea hydrolysis according to claim 2, characterized in that: It also includes a steam heating automatic shut-off valve (6) provided on a connecting pipeline between the plant area auxiliary steam inlet (10) and the urea solution storage device (4).
4. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a hydrophobic heating automatic shut-off valve (7) provided on the communication pipeline between the hydrophobic circulation pump (3) and the urea solution storage device (4).
5. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a drain valve group (5), and the drain device (2), the drain valve group (5), and the urea solution storage device (4) are connected in sequence.
6. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a liquid level meter (22) arranged on the hydrophobic device (2).
7. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a hydrophobic device temperature measuring point (21) arranged on the hydrophobic device (2).
8. The system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: It also includes a storage device temperature measuring point (8) arranged on the urea solution storage device (4).
9. A system for recovering waste heat from urea hydrolysis according to claim 1, characterized in that: The urea solution storage device (4) is a urea solution storage tank.
10. A system for recovering waste heat from urea hydrolysis according to any one of claims 1 to 9, characterized in that: The heating device (41) is a heat exchange coil.