Operating system for optimizing high-pressure steam attemperation water

Abstract

The invention provides an operating system for optimizing high-pressure steam attemperation water, and relates to the technical field of ammonia synthesis. In the operation system, a high-pressure steam coil is arranged at the bottom of a first-section furnace convection section, a water supply coil is arranged at the top of the first-section furnace convection section, an inlet of the high-pressure steam coil is connected with an outlet of a first high-pressure steam pocket through a steam pipeline, and an inlet of the water supply coil is connected with an outlet of a boiler water supply pump through a first water supply pipeline; an outlet of the water supply coil pipe is connected with an inlet of the first high-pressure steam pocket; an outlet of the boiler feed pump is connected with an inlet of the heat exchanger through a second feed pipeline. An outlet of the heat exchanger is connected with a third feed pipeline, a fourth feed pipeline and a desuperheating water pipeline. The third water supply pipeline is connected with an inlet of the second high-pressure steam pocket, the fourth water supply pipeline is connected with an inlet of the first high-pressure steam pocket, and the attemperation water pipeline is connected with the high-pressure steam coil. The flue gas emission temperature of the first-section furnace can be reduced while the steam yield is increased, and the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of synthetic ammonia, and in particular to an operating system for optimizing high-pressure steam desuperheating water. Background Art

[0002] In the Brownian process, the bottom of the convection section of the first furnace is a high-pressure steam coil. After the coil absorbs the heat of the flue gas in the radiation section, it needs cooling water to control the temperature of the high-pressure steam. In the original Brownian process, the high-pressure steam cooling water is designed to be provided by the boiler feed water pump. After the cooling water is added, it becomes high-pressure steam due to phase change. The cooling water has a low temperature and a small flow rate. Although it can achieve a cooling effect, the steam output in the process is low and the flue gas discharge temperature of the first furnace is high. Summary of the invention

[0003] The object of the present invention is to provide an operating system for optimizing high-pressure steam desuperheating water, which can reduce the exhaust temperature of flue gas from a first stage furnace while increasing steam production, thereby achieving the purpose of energy saving and emission reduction.

[0004] The present invention is achieved through the following technical solutions:

[0005] An operating system for optimizing high-pressure steam desuperheating water, wherein a high-pressure steam coil is arranged at the bottom of a first furnace convection section, and a water supply coil is arranged at the top, the inlet of the high-pressure steam coil is connected to the outlet of a first high-pressure steam drum through a steam pipeline, the inlet of the water supply coil is connected to the outlet of a boiler feed water pump through a first water supply pipeline, and the outlet of the water supply coil is connected to the inlet of the first high-pressure steam drum;

[0006] The outlet of the boiler feed water pump is connected to the inlet of the heat exchanger through the second feed water pipeline, and the outlet of the heat exchanger is connected to the third feed water pipeline, the fourth feed water pipeline and the desuperheating water pipeline respectively;

[0007] The third water supply pipeline is connected to the inlet of the second high-pressure steam drum, the fourth water supply pipeline is connected to the inlet of the first high-pressure steam drum, and the cooling water pipeline is connected to the high-pressure steam coil; wherein, a cooling nozzle is provided on the cooling water pipeline, and the outlet end of the cooling nozzle is connected to the interior of the high-pressure steam coil.

[0008] Since the boiler feed water pump provides water for the two high-pressure drums and provides cooling water for the high-pressure steam, the boiler feed water pressure is 13.5MPa and the temperature is 139℃. Among them, the water inlet of the first high-pressure drum is divided into two parts. One part enters after being preheated by the topmost coil of the convection section of the first furnace, and its boiler feed water temperature is heated to 293℃. The other part of the boiler feed water enters after passing through the heat exchanger. After heat exchange, the pressure is 13.4MPa and the temperature is 275℃. During the whole process, the steam production of the first and second high-pressure drums is basically constant, so the total amount of water inlet of the two parts of the first high-pressure drum remains basically unchanged. If the water inlet from the heat exchanger to the first high-pressure drum is reduced, the water volume of the boiler feed water to the coil of the convection section of the first furnace will inevitably increase, which can reduce the flue gas emission temperature of the first furnace, but the steam production will decrease. If the water inlet from the heat exchanger to the first high-pressure drum is increased, the water volume of the boiler feed water to the coil of the convection section of the first furnace will inevitably decrease, which can increase the steam production, but the flue gas emission temperature of the first furnace is higher. Therefore, under the premise of ensuring that the water consumption of the heat exchanger remains basically unchanged, by adjusting the water inlet from the heat exchanger to the first high-pressure steam drum, it is impossible to increase steam production and reduce the flue gas emission temperature of the first stage furnace at the same time. The two cannot be taken into account at the same time.

[0009] The output of high-pressure steam determines the output of synthetic ammonia. In order to ensure the output of high-pressure steam in conventional processes, the method used is to increase the flow of fuel gas and increase the heat load of the first stage furnace. However, this will cause excessive consumption of hot fuel in the first stage furnace, high heat load, and easy failure. Or increase the water consumption of the heat exchanger, which will consume a lot of water resources and high costs.

[0010] The applicant found that the temperature of the cooling water directly provided by the boiler feed water pump outlet is 139°C, the pressure is 13.5MPa, and the flow rate is 4.3T / h. The pressure of the water at the heat exchanger outlet is 13.4MPa, and the flow rate is 31t / h. The feed water pressure of the boiler feed water pump cooling water is 13.5MPa, and the feed water pressure of the heat exchanger outlet is 13.4MPa. Among them, the heat exchanger feed water pressure can meet the feed water pressure of the boiler feed water pump cooling water. Therefore, the applicant can increase the steam production and reduce the exhaust temperature of the flue gas of the first stage furnace by modifying the cooling water route and using the heat exchanger to provide cooling water for high-pressure steam while maintaining the water consumption of the heat exchanger basically unchanged, thereby achieving the purpose of energy saving and emission reduction.

[0011] The cooling nozzle can deliver the cooling water at the outlet of the heat exchanger into the cooling zone in the form of atomized droplets, and use the vaporization of water to absorb the sensible heat of the high-temperature synthesis gas, thereby achieving the purpose of rapid cooling. The cooling water temperature at the outlet of the heat exchanger is higher than the cooling water temperature of the boiler feed water pump. When the cooling water cools the high-pressure steam, on the one hand, it can accelerate the vaporization rate of the cooling water, thereby accelerating the high-pressure steam generation rate. On the other hand, due to the high temperature of the cooling water, the required cooling water flow rate becomes larger, and the amount of cooling water vaporization increases, thereby increasing the high-pressure steam production. In this way, there is no need to increase the flow rate of fuel gas or the water consumption of the heat exchanger to increase the high-pressure steam production, improve the production of synthetic ammonia, and achieve significant energy-saving and consumption-reducing effects.

[0012] Furthermore, a valve group is provided on the cooling water pipeline, and the valve group includes a check valve, an electric gate valve I, a cooling water regulating valve and an electric gate valve II which are connected in sequence.

[0013] Since the water supply pressure at the outlet of the heat exchanger is higher than the water supply pressure after the valve group on the desuperheating water pipeline, there is a hidden danger of bypassing the high-pressure heating during operation. The present invention adds a check valve to the desuperheating water pipeline to prevent the valve from leaking internally and causing bypassing the high-pressure heating, thereby improving the safety of process production. In addition, the desuperheating water flow rate is adjusted by the electric gate valve I, the desuperheating water regulating valve and the electric gate valve II, so that the desuperheating water can adjust the temperature of the high-pressure steam, which can effectively prevent the occurrence of overheating and improve the safety of the process.

[0014] Furthermore, the outlet of the boiler feed water pump is connected to the desuperheating water pipeline via a desuperheating water standby pipeline, and an electric gate valve III is provided on the desuperheating water standby pipeline.

[0015] The boiler feed pump and the cooling water pipeline are connected through the cooling water backup pipeline, which is controlled by the electric gate valve III. By using the electric gate valve III and the valve group, the boiler feed pump and the heat exchanger can serve as backup cooling water for each other, realize non-disturbance switching of cooling water, and use them in isolation for mutual maintenance, ensuring the independence of the two water sources and improving the reliability of cooling water operation.

[0016] Furthermore, the third water supply pipeline is provided with an electric gate valve IV, and the fourth water supply pipeline is provided with an electric gate valve V. The water volume of the third water supply pipeline is controlled by the electric gate valve IV, thereby adjusting the water volume from the heat exchanger to the second high-pressure drum; the water volume of the fourth water supply pipeline is controlled by the electric gate valve V, thereby adjusting the water volume from the heat exchanger to the first high-pressure drum. In coordination with the valve group of the desuperheating water pipeline, the water volume of the desuperheating water from the heat exchanger to the desuperheating water pipeline is adjusted, so that the desuperheating water can increase the high-pressure steam output while cooling the high-pressure steam.

[0017] Furthermore, a group of superheated steam coils are provided at the bottom of the convection section of the furnace, and the superheated steam coils are connected to the high-pressure steam coils.

[0018] Excessive high-pressure steam production will cause the outlet of the mixed raw gas coil to overheat, resulting in a first-stage furnace failure. The present invention adds a set of superheated steam coils at the bottom of the first-stage furnace convection section, which can move heat upward to prevent the raw gas coil from overheating.

[0019] Furthermore, a plurality of thermocouples are arranged below the high-pressure steam coil.

[0020] The high-pressure steam coil and superheated steam coil in the convection section of the first furnace were damaged, mainly due to the limited thermal expansion at high temperature. The entire coil is distributed in multiple layers, with a steam inlet temperature of 350°C, an outlet temperature of 510°C, a flue gas inlet temperature of 1000°C, and an outlet temperature of 830°C. The expansion amount of each layer of coil is different, and the stress generated acts on the elbow connecting the upper and lower coils. When the wall temperature of the coil in the furnace rises and the expansion stress is greater than the free deformation stress of the elbow, the coil changes from outward expansion to inward expansion. Under the condition of no expansion margin, the coil undergoes linear deformation. Afterwards, the generated expansion stress acts on the supporting tube plate, which finally causes excessive force and fracture damage. The present invention arranges multiple thermocouples under the coil, so that the inlet flue gas temperature can be controlled not to exceed 1000°C during operation, further ensuring that the steam coil system does not overheat during production.

[0021] Furthermore, the flow rate of the cooling water on the cooling water pipeline is 9-10 t / h, and the temperature of the cooling water on the cooling water pipeline is 270-280°C.

[0022] 9-10t / h of water from the heat exchanger outlet is divided into the cooling water pipeline for use as high-pressure steam cooling water. Then the water volume from the heat exchanger outlet to the first high-pressure drum will be reduced accordingly, which will increase the water volume from the boiler feed water pump to the water supply coil in the first stage furnace, increase the heat exchange of the water supply coil, and reduce the flue gas emission temperature by 5°C compared with when the boiler feed water pump provides cooling water, greatly reducing the flue gas emission temperature of the first stage furnace, achieving the purpose of energy saving and emission reduction. In addition, the high-pressure steam cooling water is increased from the original 4-4.5t / h to 9-10t / h, which increases the system's high-pressure steam production by 5.7t / h. The present invention increases the cooling water temperature, and when the cooling water cools the high-pressure steam, the required cooling water volume increases, thereby increasing the cooling water flow rate, so as to achieve the purpose of increasing the steam production of high-pressure steam.

[0023] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0024] By providing cooling water through the heat exchanger, adjusting the cooling water temperature and flow rate, and keeping the water consumption of the heat exchanger basically unchanged, the system's high-pressure steam production is increased, the flue gas emission temperature of the first stage furnace is reduced, and the thermal efficiency of the first stage furnace is improved, achieving the purpose of energy saving and emission reduction. At the same time, the coil in the furnace does not overheat, reducing the failure of the first stage furnace and extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram of an operating system for optimizing high-pressure steam desuperheating water provided in an embodiment of the present invention.

[0026] Icons: 1-first furnace convection section, 2-high-pressure steam coil, 3-feed water coil, 4-steam pipeline, 5-first high-pressure steam drum, 6-first feed water pipeline, 7-boiler feed water pump, 8-second feed water pipeline, 9-heat exchanger, 10-third feed water pipeline, 11-fourth feed water pipeline, 12-cooling water pipeline, 13-second high-pressure steam drum, 14-check valve, 15-electric gate valve I, 16-cooling water regulating valve, 17-electric gate valve II, 18-cooling water standby pipeline, 19-electric gate valve III, 20-electric gate valve IV, 21-electric gate valve V. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0028] Example 1

[0029] like Figure 1 As shown, this embodiment provides an operating system for optimizing high-pressure steam desuperheating water, a high-pressure steam coil 2 is arranged at the bottom of a first furnace convection section 1, and a water supply coil 3 is arranged at the top, the inlet of the high-pressure steam coil 2 is connected to the outlet of the first high-pressure steam drum 5 through a steam pipeline 4, the inlet of the water supply coil 3 is connected to the outlet of the boiler feed water pump 7 through a first water supply pipeline 6, and the outlet of the water supply coil 3 is connected to the inlet of the first high-pressure steam drum 5;

[0030] The outlet of the boiler feed water pump 7 is connected to the inlet of the heat exchanger 9 through the second feed water pipeline 8, and the outlet of the heat exchanger 9 is connected to the third feed water pipeline 10, the fourth feed water pipeline 11 and the desuperheating water pipeline 12 respectively;

[0031] The third water supply pipeline 10 is connected to the inlet of the second high-pressure steam drum 13, the fourth water supply pipeline 11 is connected to the inlet of the first high-pressure steam drum 5, and the cooling water pipeline 12 is connected to the high-pressure steam coil 2; wherein, a cooling nozzle is provided on the cooling water pipeline 12, and the outlet end of the cooling nozzle is connected to the interior of the high-pressure steam coil 2.

[0032] The desuperheating water pipeline 12 is provided with a valve group, which includes a check valve 14, an electric gate valve I15, a desuperheating water regulating valve 16 and an electric gate valve II17 which are connected in sequence.

[0033] The outlet of the boiler feed water pump 7 is connected to the desuperheating water pipeline 12 via a desuperheating water standby pipeline 18 , and an electric gate valve III19 is provided on the desuperheating water standby pipeline 18 .

[0034] The third water supply pipeline 10 is provided with an electric gate valve IV20 , and the fourth water supply pipeline 11 is provided with an electric gate valve V21 .

[0035] A group of superheated steam coils are also provided at the bottom of the first stage furnace convection section 1 , and the superheated steam coils are connected to the high-pressure steam coils 2 .

[0036] A plurality of thermocouples are arranged below the high-pressure steam coil 2 .

[0037] The flow rate of the cooling water on the cooling water pipeline 12 is 9 t / h, and the temperature of the cooling water on the cooling water pipeline 12 is 270°C.

[0038] Initially, all valves are closed.

[0039] When in use, open the check valve 14, the electric gate valve I15, the desuperheating water regulating valve 16, the electric gate valve II17, the electric gate valve IV20 and the electric gate valve V21, start the boiler feed water pump 7, part of the water of the boiler feed water pump 7 is transported to the water supply coil 3 through the first water supply pipeline 6, the water in the water supply coil 3 is transported to the first high-pressure steam drum 5 after flue gas heat exchange, and the other part is transported to the heat exchanger 9 through the second water supply pipeline 8. The water treated by the heat exchanger 9 is transported in three ways, one way is transported to the second high-pressure steam drum 13 through the third water supply pipeline 10, one way is transported to the first high-pressure steam drum 5 through the fourth water supply pipeline 11, and one way is sprayed from the desuperheating nozzle to the high-pressure steam coil 2 through the desuperheating water pipeline 12, the water of the first high-pressure steam drum 5 is transported to the high-pressure steam coil 2 through the steam pipeline 4, and the high-pressure steam coil 2 is cooled by the desuperheating water.

[0040] Example 2

[0041] In this embodiment, the flow rate of the cooling water on the cooling water pipeline 12 is 9.5 t / h, and the temperature of the cooling water on the cooling water pipeline 12 is 275° C. The rest is the same as that of the embodiment 1.

[0042] Example 3

[0043] In this embodiment, the flow rate of the cooling water on the cooling water pipeline 12 is 10 t / h, and the temperature of the cooling water on the cooling water pipeline 12 is 280° C. The rest is the same as that of the embodiment 1.

[0044] Comparative Example 1

[0045] In this comparative example, the flow rate of the cooling water on the cooling water pipeline 12 is 6 t / h, and the temperature of the cooling water on the cooling water pipeline 12 is 275° C. The rest is the same as in Example 1.

[0046] Comparative Example 2

[0047] In this comparative example, the flow rate of the cooling water on the cooling water pipeline 12 is 9 t / h, and the temperature of the cooling water on the cooling water pipeline 12 is 240° C. The rest is the same as in Example 1.

[0048] Test results

[0049] The steam production increase and the flue gas exhaust temperature reduction of Examples 1-3 and Comparative Examples 1-2 were tested, and the boiler feed water pump 7 provided cooling water (cooling water temperature was 139° C., cooling water flow rate was 4.3 t / h) as the control group. The steam production increase and the flue gas exhaust temperature reduction were compared based on the control group, and the results were as follows:

[0050] Table 1 Test results of Examples 1-3 and Comparative Examples 1-2

[0051]

[0052] According to Table 1, compared with Comparative Example 1-2, Example 1-3 has a higher increase in steam production and a greater decrease in smoke exhaust temperature. This shows that using heat exchanger 9 to provide cooling water and controlling the amount and temperature of cooling water can increase the high-pressure steam production in the first stage furnace and reduce the smoke exhaust temperature. If the amount and temperature of cooling water exceed or fall below the amount and temperature of cooling water, the high-pressure steam production and smoke exhaust temperature will be affected.

[0053] In summary, the operating system for optimizing high-pressure steam cooling water provided by the present invention can increase the system's high-pressure steam production, reduce the exhaust temperature of the first-stage furnace flue gas, and improve the thermal efficiency of the first-stage furnace, thereby achieving the purpose of energy conservation and emission reduction, while keeping the water consumption of the heat exchanger basically unchanged.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An operating system for optimizing high-pressure steam desuperheating water, characterized in that: A high-pressure steam coil is provided at the bottom of a first furnace convection section, and a water supply coil is provided at the top, the inlet of the high-pressure steam coil is connected to the outlet of the first high-pressure steam drum through a steam pipeline, the inlet of the water supply coil is connected to the outlet of the boiler feed water pump through a first water supply pipeline, and the outlet of the water supply coil is connected to the inlet of the first high-pressure steam drum; The outlet of the boiler feed water pump is connected to the inlet of the heat exchanger through the second feed water pipeline, and the outlet of the heat exchanger is connected to the third feed water pipeline, the fourth feed water pipeline and the desuperheating water pipeline respectively; The third water supply pipeline is connected to the inlet of the second high-pressure steam drum, the fourth water supply pipeline is connected to the inlet of the first high-pressure steam drum, and the cooling water pipeline is connected to the high-pressure steam coil; wherein, a cooling nozzle is provided on the cooling water pipeline, and the outlet end of the cooling nozzle is connected to the interior of the high-pressure steam coil.

2. The operating system for optimizing high-pressure steam desuperheating water according to claim 1, characterized in that: The cooling water pipeline is provided with a valve group, which includes a check valve, an electric gate valve I, a cooling water regulating valve and an electric gate valve II which are connected in sequence.

3. The operating system for optimizing high-pressure steam desuperheating water according to claim 1, characterized in that: The outlet of the boiler feed water pump is connected to the desuperheating water pipeline through a desuperheating water standby pipeline, and an electric gate valve III is arranged on the desuperheating water standby pipeline.

4. The operating system for optimizing high-pressure steam desuperheating water according to claim 1, characterized in that: The third water supply pipeline is provided with an electric gate valve IV, and the fourth water supply pipeline is provided with an electric gate valve V.

5. The operating system for optimizing high-pressure steam desuperheating water according to claim 1, characterized in that: A group of superheated steam coils are also arranged at the bottom of the convection section of the first stage furnace, and the superheated steam coils are connected to the high-pressure steam coils.

6. The operating system for optimizing high-pressure steam desuperheating water according to claim 5, characterized in that: A plurality of thermocouples are arranged below the high-pressure steam coil.

7. The operating system for optimizing high-pressure steam desuperheating water according to claim 1, characterized in that: The flow rate of the cooling water on the cooling water pipeline is 9-10 t / h, and the temperature of the cooling water on the cooling water pipeline is 270-280°C.

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