Low-temperature shift converter inlet temperature reducing device and synthesis ammonia system
By renovating the connection between the boiler water supply pump and the water spray cooler, the water flow rate of the boiler water supply preheater is increased, and the problem of excessive temperature inlet temperature of the low-temperature conversion furnace is solved, which extends the service life of the catalyst and maintains the balance of the steam system.
Patent Information
- Application Number
- CN202420742256.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-10
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2034-04-10
AI Technical Summary
The high inlet temperature of the low-temperature converter furnace causes the catalyst to operate at higher temperatures for a long time, reducing its activity and service life. At the same time, increasing the water supply of the boiler feed water pump will destroy the steam system balance.
By renovating the connecting pipe between the boiler water supply pump and the water spray cooler, the water outlet of the boiler water supply preheater is connected to the steam drum, and the water outlet of the water spray cooler and the boiler water supply preheater are connected through the first pipeline to ensure that The water supply volume of the boiler feed water pump remains unchanged, and the water flow rate of the boiler feed water preheater is increased to improve heat exchange efficiency to reduce the inlet temperature of the low-temperature transformer furnace.
It effectively reduces the inlet temperature of the low-temperature converter furnace, extends the service life of the catalyst, and maintains the balance of the steam system, avoiding the decline in steam quality.
Smart Images
Figure CN222143003U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of synthetic ammonia, and in particular to a low-temperature conversion furnace inlet temperature reduction device and a synthetic ammonia system. Background Art
[0002] In the natural gas to ammonia synthesis plant, most of the process technology flows are equipped with high and low temperature conversion reactions, that is, the carbon monoxide and water vapor in the natural gas are reacted through the catalyst in the high and low temperature conversion furnace to generate carbon dioxide and the hydrogen required for the synthesis of ammonia.
[0003] The process gas in the high-temperature shift furnace enters the inlet of the low-temperature shift furnace after being cooled by two-stage heat exchange between the waste heat boiler and the boiler feed water preheater and the water supplied by the boiler feed water pump. The design temperature of the low-temperature shift furnace inlet is between 185-210℃. In addition to supplying water to the boiler feed water preheater, the boiler feed water pump is also connected to the nozzle cooler through a pipeline to supply water to the spray water cooler to reduce the temperature of the high-pressure pipeline; the water outlet of the boiler feed water preheater is connected to the steam drum.
[0004] With the decline in the efficiency of the boiler feed water preheater, or the small margin of the equipment design itself, the inlet temperature of most low-temperature conversion furnaces is slightly higher than the design value, causing the low-temperature conversion catalyst to operate at a higher temperature for a long time. Not only can the low-temperature activity of the catalyst not be utilized, but the service life of the catalyst is also significantly affected. Especially for old production equipment that has been in operation for many years, the service life of the catalyst is reduced to one to two years due to the increase in the inlet temperature. In addition, since the water supply of the boiler feed water pump is fixed, although the additional water supply of the boiler feed water pump can increase the heat exchange efficiency of the boiler feed water preheater and reduce the inlet temperature of the low-temperature conversion furnace, increasing the water supply of the boiler feed water pump will destroy the balance of the entire steam system, thereby reducing the steam quality. Utility Model Content
[0005] The purpose of the embodiments of the present application is to provide a low-temperature conversion furnace inlet temperature reduction device and a synthetic ammonia system, so as to reduce the temperature of the low-temperature conversion furnace inlet while ensuring that the water supply of the boiler feed water pump remains unchanged, thereby increasing the service life of the catalyst without destroying the steam balance.
[0006] In order to solve the above technical problems, the embodiments of the present application provide the following technical solutions:
[0007] A first aspect of the present application provides a low temperature conversion furnace inlet temperature reduction device, comprising:
[0008] a boiler feed water preheater, wherein the water inlet of the boiler feed water preheater is connected to the boiler feed water pump, the water outlet of the boiler feed water preheater is used to be connected to the steam drum, the air inlet of the boiler feed water preheater is used to be connected to the air outlet of the waste heat boiler, and the air outlet of the boiler feed water preheater is used to be connected to the inlet of the low-temperature shift furnace; and
[0009] A water spray cooler is connected to a water outlet of a boiler feed water preheater through a first pipeline.
[0010] In some modified implementations of the first aspect of the present application, the water outlet of the boiler feed water preheater is connected to the steam drum through a second pipe, the second pipe is connected to one end of the first pipe, and a flow valve is provided on the second pipe, and the flow valve is provided between the connection between the second pipe and the first pipe and the steam drum.
[0011] In some modified implementations of the first aspect of the present application, the boiler feed water pump is connected to the first pipeline through a third pipeline.
[0012] In some modified implementations of the first aspect of the present application, a first shut-off valve is provided on the first pipeline, the first shut-off valve is provided between the connection between the first pipeline and the third pipeline and the water outlet of the boiler feed water preheater, and a second shut-off valve is provided on the third pipeline.
[0013] In some modified implementations of the first aspect of the present application, the first cut-off valve is a flow control valve.
[0014] In some modified implementations of the first aspect of the present application, a check valve is provided on the first pipeline.
[0015] In some modified implementations of the first aspect of the present application, a third shut-off valve is provided on the first pipeline, and the third shut-off valve is provided between the connection between the first pipeline and the third pipeline and the water outlet of the boiler feed water preheater.
[0016] In some modified implementations of the first aspect of the present application, a fourth cut-off valve is provided on the third pipeline.
[0017] In some modified implementations of the first aspect of the present application, the water inlet of the boiler feed water preheater is connected to the boiler feed water pump through a fourth pipe, and the fourth pipe is connected to the third pipe.
[0018] A second aspect of the present application provides a synthetic ammonia system, comprising a low-temperature conversion furnace inlet temperature reducing device as claimed in the above-mentioned claim.
[0019] Compared with the prior art, the low-temperature conversion furnace inlet temperature reducing device provided in the present application, on the basis of connecting the water outlet of the boiler feed water preheater with the steam drum, changes the original boiler feed water pump and water spray cooler connecting pipe into a first pipe connected to the water outlet of the boiler feed water preheater and the water spray cooler respectively; thereby, while ensuring that the total amount of the boiler feed water pump remains unchanged, the boiler water flow entering the boiler feed water preheater is increased, thereby improving the heat exchange amount and heat exchange efficiency of the boiler feed water preheater, and achieving the purpose of reducing the inlet temperature of the low-temperature conversion furnace, thereby ensuring that the water feed amount of the boiler feed water pump remains unchanged, while the low-temperature activity of the low-temperature conversion catalyst is exerted to a greater extent, thereby increasing the service life of the catalyst and not destroying the steam balance. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:
[0021] Figure 1 The structure diagram of a low temperature shift furnace inlet temperature reduction device is schematically shown;
[0022] Description of Figure Numbers:
[0023] 1. Boiler feed water preheater; 2. Boiler feed water pump; 3. Waste heat boiler; 4. Low-temperature conversion furnace; 5. Water spray cooler; 6. First pipeline; 7. Second pipeline; 8. First shut-off valve; 9. Check valve; 10. Third shut-off valve; 11. Second shut-off valve; 12. Fourth shut-off valve; 13. Third pipeline; 14. High-pressure pipeline; 15. Fourth pipeline; 16. Steam drum. DETAILED DESCRIPTION
[0024] The following is a further detailed description of the implementation methods of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application. The present application can be implemented in many different forms and is not limited to the specific embodiments of the present application, but includes all technical solutions that fall within the scope of the claims.
[0025] The present application provides these embodiments to make the present application thorough and complete, and to fully express the scope of the present application to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of the materials, the numerical expressions and the numerical values set forth in these embodiments should be interpreted as being merely exemplary, and not as limiting.
[0026] It should be noted that, in the description of this application, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.
[0027] In addition, the words "first", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish different parts. "Vertical" does not mean vertical in the strict sense, but is within the tolerance range. "Parallel" does not mean parallel in the strict sense, but is within the tolerance range. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.
[0028] It should also be noted that in the description of this application, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.
[0029] All terms used in this application have the same meaning as those understood by those of ordinary skill in the art to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, such as general dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.
[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.
[0031] The process gas in the high-temperature shift furnace enters the inlet of the low-temperature shift furnace after being cooled by two-stage heat exchange between the waste heat boiler and the boiler feed water preheater and the water supplied by the boiler feed water pump. The design temperature of the low-temperature shift furnace inlet is between 185-210℃. Among them, in addition to supplying water to the boiler feed water preheater, the boiler feed water pump is also connected to the nozzle cooler through a pipeline to supply water to the spray water cooler to reduce the temperature of the high-pressure pipeline. The water outlet of the boiler feed water preheater is connected to the steam drum.
[0032] With the decline in the efficiency of the boiler feed water preheater, or the small margin of the equipment design itself, the inlet temperature of most low-temperature conversion furnaces is slightly higher than the design value, causing the low-temperature conversion catalyst to operate at a higher temperature for a long time. Not only can the low-temperature activity of the catalyst not be utilized, but the service life of the catalyst is also significantly affected. Especially for old production equipment that has been in operation for many years, the service life of the catalyst is reduced to one to two years due to the increase in the inlet temperature. In addition, since the water supply of the boiler feed water pump is fixed, although the additional water supply of the boiler feed water pump can increase the heat exchange efficiency of the boiler feed water preheater and reduce the inlet temperature of the low-temperature conversion furnace, increasing the water supply of the boiler feed water pump will destroy the balance of the entire steam system, thereby reducing the steam quality.
[0033] In order to solve the above technical problems, the present application provides a low-temperature conversion furnace inlet temperature reduction device and a synthetic ammonia system, so as to reduce the temperature of the low-temperature conversion furnace inlet while ensuring that the water supply of the boiler feed water pump remains unchanged, thereby increasing the service life of the catalyst without destroying the steam balance.
[0034] Example 1
[0035] like Figure 1 As shown, a device for reducing the inlet temperature of a low-temperature conversion furnace 4 includes a boiler feed water preheater 1 and a water spray cooler 5. The water inlet of the boiler feed water preheater 1 is connected to the boiler feed water pump 2, the water outlet of the boiler feed water preheater 1 is used to be connected to the steam drum 16, the air inlet of the boiler feed water preheater 1 is used to be connected to the air outlet of the waste heat boiler 3, and the air outlet of the boiler feed water preheater 1 is used to be connected to the inlet of the low-temperature conversion furnace 4; the water spray cooler 5 is connected to the water outlet of the boiler feed water preheater 1 through a first pipe 6.
[0036] The boiler feed water preheater 1 is a gas-liquid heat exchanger used to preheat the water in the boiler feed water pump 2 and cool the process gas that is about to enter the low-temperature shift furnace 4. Specifically, the boiler feed water preheater 1 can be a shell and tube preheater, a fin tube preheater, a spiral plate preheater, and a heat pipe preheater. As long as the boiler feed water preheater 1 can exchange heat between the process gas that is about to enter the low-temperature shift furnace 4 and the water in the boiler feed water pump 2, the specific structure and type of the boiler feed water preheater 1 are not specifically limited.
[0037] The water spray cooler 5 is a water spray cooler used to cool the steam in the high-pressure pipeline 14. Specifically, the water spray cooler 5 includes a cylindrical header, a venturi nozzle and a nozzle. The cylindrical header is connected to the high-pressure steam pipeline, the venturi nozzle is arranged in the cylindrical header, the nozzle is arranged at the throat of the venturi nozzle, and the nozzle is connected to the first pipe 6. Low-temperature water is sprayed into the high-pressure steam pipeline through the nozzle, so that the low-temperature water absorbs heat and changes into water vapor, thereby cooling the water vapor in the high-pressure steam pipeline. As long as the nozzle cooler can be connected to the first pipeline 6 and can spray water to cool the water vapor in the high-pressure steam pipeline, the specific structure of the water spray cooler 5 is not limited. Among them, the high-pressure pipeline 14 is provided with multiple, and the multiple high-pressure pipelines 14 are connected to a main line to form an official website, and the main line is connected to a boiler that provides steam.
[0038] The waste heat boiler 3 is a device that efficiently utilizes the waste heat resources generated in the industrial production process and converts them into useful thermal energy (usually steam or hot water). The waste heat boiler 3 can be connected to the gas outlet of the high-temperature converter, and the high-temperature process gas flowing out of the high-temperature converter is used to convert the water entering the waste heat boiler 3 into water vapor while cooling the high-temperature process gas in the high-temperature converter. Specifically, the waste heat boiler 3 can be a shell and tube waste heat boiler 3, a flue waste heat boiler 3, a double-tube waste heat boiler 3, and a spiral tube waste heat boiler 3. As long as the waste heat boiler 3 can exchange heat between the high-temperature process gas and water, the structure of the waste heat boiler 3 is not specifically limited.
[0039] Specifically, the waste heat boiler 3 can be connected to the water outlet of the boiler feed water preheater 1 through the drum 16, that is, the boiler feed water preheater 1 is connected to the drum 16 through a pipeline, and the drum 16 is connected to the waste heat boiler 3 through a pipeline. More specifically, a circulation loop is formed between the drum 16 and the waste heat boiler 3 through an ascending pipe (or evaporation pipe) and a downcomer. The ascending pipe sends the steam-water mixture heated by the waste heat boiler 3 into the drum 16, and the downcomer sends the separated water from the drum 16 back to the waste heat boiler 3 for further heating.
[0040] The boiler feed water pump 2 is a water pump used to supply water to the boiler feed water preheater 1. Specifically, the boiler feed water pump 2 is usually a pump type that can withstand high pressure and has good stability, such as a multi-stage centrifugal pump. More specifically, it can be an axially split multi-stage pump, a radially split multi-stage pump, a corrosion-resistant pump of special material and design, and a self-balancing multi-stage pump. As long as the boiler feed water pump 2 can continuously and stably supply a fixed flow of water to the system, there is no specific limitation on the specific structure and type of the boiler feed water pump 2.
[0041] Compared with the prior art, the device for reducing the inlet temperature of the low-temperature conversion furnace 4 provided in the present application, on the basis of connecting the water outlet of the boiler feed water preheater 1 with the steam drum 16, changes the original connecting pipe of the boiler feed water pump 2 and the water spray cooler 5 into a first pipe 6 respectively connected to the water outlet of the boiler feed water preheater 1 and the water spray cooler 5; thereby, while ensuring that the total amount of the boiler feed water pump 2 remains unchanged, the boiler water flow rate entering the boiler feed water preheater 1 is increased, thereby improving the heat exchange amount and heat exchange efficiency of the boiler feed water preheater 1, and achieving the purpose of reducing the inlet temperature of the low-temperature conversion furnace 4, thereby ensuring that the water feed amount of the boiler feed water pump 2 remains unchanged, while the low-temperature activity of the low-temperature conversion catalyst is exerted to a greater extent, thereby increasing the service life of the catalyst and not destroying the steam balance.
[0042] In some modified implementations, the water outlet of the boiler feed water preheater 1 is connected to the waste heat boiler 3 through the second pipe 7, the second pipe 7 is connected to one end of the first pipe 6, and a flow valve is provided on the second pipe 7, and the flow valve is provided between the connection between the second pipe 7 and the first pipe 6 and the waste heat boiler 3. Specifically, the second pipe 7 is the main pipe for the outlet of the boiler feed water preheater 1, and the pipe diameter is relatively large. The first pipe 6 requires a smaller flow rate and a smaller pipe diameter, and the second pipe 7 can be connected to the side wall of the first pipe 6.
[0043] The flow valve is a flow control valve, which is arranged between the connection between the second pipeline 7 and the first pipeline 6 and the waste heat boiler 3, so as to control the flow of the boiler feed water preheater 1 into the steam drum 16, ensure that the flow into the steam drum 16 remains unchanged, further ensure the balance of the steam system, and avoid the decline of steam quality.
[0044] In some modified implementations, the boiler feed water pump 2 is connected to the first pipe 6 via the third pipe 13. By setting the third pipe 13 to be connected to the first pipe 6, when the system is started or stopped, no feed water enters the boiler feed water preheater 1 or when the medium-pressure steam temperature is high, the supply of feed water to the water spray cooler 5 can be guaranteed.
[0045] In some modified implementations, a first shut-off valve 8 is provided on the first pipeline 6, and the first shut-off valve 8 is provided between the connection between the first pipeline 6 and the third pipeline 13 and the water outlet of the boiler feed water preheater 1, and a second shut-off valve 11 is provided on the third pipeline 13. By providing the first shut-off valve 8 on the first pipeline 6 and the second shut-off valve 11 on the third pipeline 13, the opening and closing of the first pipeline 6 and the third pipeline 13 are controlled, and then different pipelines are switched under different working conditions. Specifically, when the system is started and shut down, when no feed water enters the boiler feed water preheater 1 or the temperature of the medium-pressure steam is high, the supply of feed water to the water spray cooler 5 can be guaranteed through the third pipeline 13; when the system is running, the third pipeline 13 can be closed, and the first pipeline 6 can be opened to supply water to the water spray cooler 5, thereby increasing the heat exchange of the boiler feed water preheater 1 and thereby reducing the temperature of the inlet of the low-temperature conversion furnace 4 while ensuring that the water supply of the boiler feed water pump 2 remains unchanged.
[0046] The first shut-off valve 8 and the second shut-off valve 11 are valves for shutting off the first pipeline 6 and the third pipeline 13. Specifically, the first shut-off valve 8 and the second shut-off valve 11 may be pneumatic shut-off valves, electric shut-off valves, and hydraulic shut-off valves; more specifically, the first shut-off valve 8 and the second shut-off valve 11 may also be flow control valves, and as long as the first shut-off valve 8 and the second shut-off valve 11 can control the opening and closing of the first pipeline 6 and the third pipeline 13, the structures and types of the first shut-off valve 8 and the second shut-off valve 11 are not specifically limited.
[0047] In some modified implementations, the first shut-off valve 8 is a flow control valve. The flow control valve controls the flow of the first pipeline 6 and cooperates with the flow valve on the second pipeline 7 to further control the output water volume of the boiler feed pump 2 to ensure the steam balance of the entire system.
[0048] In some modified implementations, a check valve 9 is provided on the first pipeline 6. The check valve 9 is provided on the first pipeline 6 to prevent the water in the water cooler 5 from flowing back into the second pipeline 7, thereby affecting the flow rate of the second pipeline 7. Specifically, the check valve 9 can be a swing check valve 9, a lift check valve 9, a butterfly check valve 9, and a pipeline check valve 9. As long as the check valve 9 can prevent the water in the water cooler from flowing back into the second pipeline 7, the structure of the check valve 9 is not specifically limited.
[0049] In some modified implementations, a third shut-off valve 10 is provided on the first pipeline 6, and the third shut-off valve 10 is provided between the connection between the first pipeline 6 and the third pipeline 13 and the water outlet of the boiler feed water preheater 1. The third shut-off valve 10 is provided to further ensure that the first pipeline 6 can be completely closed, thereby ensuring that the first pipeline 6 can be stably controlled.
[0050] In some modified implementations, a fourth shut-off valve 12 is provided on the third pipeline 13. The fourth shut-off valve 12 is provided to further ensure that the third pipeline 13 can be completely closed, thereby ensuring that the third pipeline 13 can be stably controlled.
[0051] Specifically, the third shut-off valve 10 and the fourth shut-off valve 12 can be pneumatic shut-off valves, electric shut-off valves and hydraulic shut-off valves; as long as the third shut-off valve 10 and the fourth shut-off valve 12 can control the opening and closing of the first pipeline 6 and the third pipeline 13, there is no specific limitation on the structure and type of the third shut-off valve 10 and the fourth shut-off valve 12.
[0052] In some modified implementations, the water inlet of the boiler feed water preheater 1 is connected to the boiler feed water pump 2 through a fourth pipe 15, and the fourth pipe 15 is connected to the third pipe 13. Connecting the third pipe 13 to the outlet pipe of the boiler feed water pump 2 makes the pipe connection process more convenient.
[0053] Example 2
[0054] A synthetic ammonia system comprises the low-temperature shift furnace 4 inlet temperature reduction device as claimed in claim 1.
[0055] Compared with the prior art, the synthetic ammonia system provided in the present application, on the basis of connecting the water outlet of the boiler feed water preheater 1 with the steam drum, changes the original connecting pipe between the boiler feed water pump 2 and the water spray cooler 5 into a first pipe 6 respectively connected to the water outlet of the boiler feed water preheater 1 and the water spray cooler 5; thereby, while ensuring that the total amount of the boiler feed water pump 2 remains unchanged, the boiler water flow entering the boiler feed water preheater 1 is increased, thereby improving the heat exchange amount and heat exchange efficiency of the boiler feed water preheater 1, achieving the purpose of reducing the inlet temperature of the low-temperature conversion furnace 4, thereby ensuring that the water feed amount of the boiler feed water pump 2 remains unchanged, while the low-temperature activity of the low-temperature conversion catalyst is exerted to a greater extent, thereby increasing the service life of the catalyst and not destroying the steam balance.
[0056] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A low temperature conversion furnace inlet temperature reduction device, characterized in that: include: A boiler feed water preheater, wherein the water inlet of the boiler feed water preheater is connected to the boiler feed water pump, the water outlet of the boiler feed water preheater is used to be connected to the steam drum, the air inlet of the boiler feed water preheater is used to be connected to the air outlet of the waste heat boiler, and the air outlet of the boiler feed water preheater is used to be connected to the inlet of the low-temperature conversion furnace; and A water spray cooler is connected to the water outlet of the boiler feed water preheater through a first pipeline.
2. The low temperature conversion furnace inlet temperature reduction device according to claim 1, characterized in that: The water outlet of the boiler feed water preheater is connected to the steam drum through a second pipe, the second pipe is connected to one end of the first pipe, a flow valve is provided on the second pipe, and the flow valve is arranged between the connection between the second pipe and the first pipe and the steam drum.
3. The low temperature conversion furnace inlet temperature reduction device according to claim 1, characterized in that: The boiler feed water pump is connected to the first pipeline through a third pipeline.
4. The low temperature conversion furnace inlet temperature reduction device according to claim 3, characterized in that: The first pipeline is provided with a first shut-off valve, which is arranged between the connection between the first pipeline and the third pipeline and the water outlet of the boiler feed water preheater, and the third pipeline is provided with a second shut-off valve.
5. The low temperature conversion furnace inlet temperature reduction device according to claim 4, characterized in that: The first cut-off valve is a flow control valve.
6. The low temperature conversion furnace inlet temperature reduction device according to claim 1, characterized in that: A check valve is arranged on the first pipeline.
7. The low temperature conversion furnace inlet temperature reduction device according to claim 4, characterized in that: The first pipeline is provided with a third shut-off valve, and the third shut-off valve is arranged between the connection between the first pipeline and the third pipeline and the water outlet of the boiler feed water preheater.
8. The low temperature conversion furnace inlet temperature reducing device according to claim 3, characterized in that: The third pipeline is provided with a fourth cut-off valve.
9. The low temperature conversion furnace inlet temperature reducing device according to claim 4, characterized in that: The water inlet of the boiler feed water preheater is connected to the boiler feed water pump through a fourth pipeline, and the fourth pipeline is connected to the third pipeline.
10. A synthetic ammonia system, characterized in that: It comprises the low temperature conversion furnace inlet temperature reducing device as described in any one of claims 1 to 9.