Cooling oxidation treatment method before replacement of ammonia synthesis catalyst
By employing a scientific cooling oxidation treatment method and utilizing existing equipment to control the catalyst temperature, the fire risk during catalyst replacement is eliminated, enabling safe and efficient catalyst replacement while reducing costs and environmental risks.
Patent Information
- Application Number
- CN202511634638.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-02-13
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
During the replacement of ammonia synthesis catalysts, the catalysts exposed to air are prone to oxidation and generate heat, leading to fire risks and a lack of safe handling measures. Existing technologies are complex and dangerous.
Through a scientific cooling oxidation treatment method, nitrogen is added to the system using existing equipment for replacement, the temperature is controlled and the oxidation reaction is carried out, avoiding catalyst exposure. A mixture of nitrogen and air is used to cool the catalyst, ensuring that the temperature does not exceed 350℃ and is eventually reduced to below 50℃.
Effectively control temperature rise, prevent fires and equipment damage, reduce harmful gas emissions, improve replacement efficiency, reduce costs, and ensure production safety and environmental protection.
Smart Images
Figure CN121513733A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of ammonia synthesis, and particularly relates to a method for cooling and oxidizing ammonia synthesis catalysts before replacement. BACKGROUND
[0002] In the ammonia synthesis industry, the performance of catalysts directly relates to the efficiency and yield of ammonia synthesis. With the extension of use time, ammonia synthesis catalysts gradually lose activity, which is manifested in problems such as a decrease in synthesis rate, an increase in system pressure, a decrease in daily ammonia production, and an increase in energy consumption. In order to maintain production efficiency and product quality, it is necessary to regularly replace catalysts.
[0003] However, during the replacement of catalysts, especially for some specific types of ammonia synthesis towers (such as the DC-D type ammonia synthesis tower produced by Nanjing Jutao Company), since the bottom is not designed with the function of automatically discharging catalysts, the upper large cover of the tower needs to be disassembled during the replacement of catalysts, and the catalysts are cleaned out from top to bottom by manual methods. This process has great safety hazards, because the catalysts are usually reduced to an active state (such as Fe) before use, and once exposed to air, they will rapidly react with oxygen to release a large amount of heat, causing the temperature of the catalyst bed to rise sharply, and even possibly causing a fire, which may seriously damage the precision components inside the ammonia synthesis tower.
[0004] In addition, since the ammonia synthesis device is often not fully considered in the design and construction of the process requirements for the replacement of catalysts in the later stage, there is a lack of corresponding safety treatment measures and equipment, making the replacement process of catalysts more complex and dangerous. Therefore, it is particularly important to develop a safe and effective method for cooling and oxidizing ammonia synthesis catalysts before replacement. SUMMARY
[0005] The present application aims to provide a method for cooling and oxidizing ammonia synthesis catalysts before replacement, to solve the problems raised in the background.
[0006] In order to achieve the above object, the present application provides the following technical scheme: a kind of ammonia synthesis catalyst replacement before cooling oxidation treatment method, including ammonia synthesis tower, the bottom of the ammonia synthesis tower is fixedly connected with synthesis gas inlet steam superheater pipeline, the synthesis gas inlet steam superheater pipeline is connected with steam superheater, one end of the steam superheater is connected with medium-pressure waste boiler, one end of the medium-pressure waste boiler is connected with desalted water heater, one end of the desalted water heater is connected with low-pressure waste boiler, one end of the low-pressure waste boiler is connected with heat exchanger, one end of the heat exchanger is connected with first water cooler, one end of the first water cooler is connected with second water cooler, one end of the second water cooler is connected with cold exchanger, one end of the cold exchanger is connected with first-stage ammonia cooler, one end of the first-stage ammonia cooler is connected with second-stage ammonia cooler, one end of the second-stage ammonia cooler is connected with ammonia separator, one end of the ammonia separator is connected with liquid ammonia storage tank, and the ammonia separator is connected with pipeline and is provided with ammonia release valve at one end close to the liquid ammonia storage tank.
[0007] As a further scheme of the present application: the steam superheater, medium-pressure waste boiler, desalted water heater, low-pressure waste boiler, heat exchanger, first water cooler, second water cooler, cold exchanger, first-stage ammonia cooler, second-stage ammonia cooler, ammonia separator and liquid ammonia storage tank are connected by pipeline at one end.
[0008] As a further scheme of the present application: the ammonia synthesis tower is connected with ammonia synthesis tower inlet pipeline at the top, and one end of the ammonia synthesis tower inlet pipeline is connected with the top of the heat exchanger.
[0009] As a further scheme of the present application: the cold exchanger is connected with synthesis gas inlet cold exchange pipeline at the top, one end of the synthesis gas inlet cold exchange pipeline is connected with venting pipeline, and a venting valve is arranged on the venting pipeline.
[0010] As a further scheme of the present application: the heat exchanger is connected with first 4.0 MPa nitrogen pipeline at the bottom, a first 4.0 MPa nitrogen valve is arranged on the first 4.0 MPa nitrogen pipeline, one end of the first 4.0 MPa nitrogen pipeline is connected with compressor high-pressure cylinder, and a compressor outlet valve is arranged on one end of the compressor high-pressure cylinder close to the first 4.0 MPa nitrogen pipeline.
[0011] As a further scheme of the present application: one end of the compressor high-pressure cylinder is connected with the bottom of the cold exchanger, and a synthesis gas inlet compressor valve is arranged on one end of the compressor high-pressure cylinder close to the cold exchanger.
[0012] As a further scheme of the present application: one end of the compressor high-pressure cylinder is connected with compressor steam turbine, a compressor medium-pressure cylinder is arranged on one end of the compressor high-pressure cylinder, a compressor low-pressure cylinder is arranged on one end of the compressor medium-pressure cylinder, the compressor high-pressure cylinder and the compressor medium-pressure cylinder are in communication with each other, and the compressor medium-pressure cylinder and the compressor low-pressure cylinder are in communication with each other.
[0013] As a further scheme of the present application: the compressor high-pressure cylinder and the compressor medium-pressure cylinder are provided with a three-to-two valve, and the compressor medium-pressure cylinder and the compressor low-pressure cylinder are provided with a two-to-one valve.
[0014] As a further scheme of the present application: the compressor low-pressure cylinder is connected with a make-up gas pipeline, the make-up gas pipeline is provided with a make-up gas valve, one end of the make-up gas pipeline is connected with a 3.0 MPa air pipeline, the 3.0 MPa air pipeline is provided with a 3.0 MPa air valve, and the make-up gas pipeline is further connected with a second 4.0 MPa nitrogen pipeline, and the second 4.0 MPa nitrogen pipeline is provided with a second 4.0 MPa nitrogen valve.
[0015] Compared with the prior art, the present application has the following advantages: in the present application, the temperature rise during catalyst replacement is effectively controlled through scientific cooling and oxidation treatment, the risks of fire and equipment damage are avoided, and the production safety is ensured. The method eliminates the direct discharge of harmful gases into the environment, reduces air pollution, and meets the environmental protection requirements.
[0016] By preventing the problems of high-temperature blocking and caking of the catalyst, the working time of personnel in the synthesis tower is reduced, and the efficiency of catalyst replacement is improved. At the same time, the catalyst in the synthesis tower can be directly extracted to the outside of the tower by a negative pressure suction device for recycling, further shortening the replacement time. Since the treatment effect is good and the operation cost is low, the method helps to reduce the total cost of catalyst replacement and improve the economic benefits of enterprises.
[0017] The process flow of the method is simple, easy to operate and control, reduces the requirement for the skill level of the operator, and improves the flexibility and reliability of production. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 Figure 1 is a schematic diagram of the equipment connection of the ammonia synthesis catalyst replacement pre-cooling and oxidation treatment method of the present application.
[0019] In the figure: 1, synthesis gas into steam superheater pipeline; 2, ammonia synthesis tower; 3, steam superheater; 4, into ammonia synthesis tower pipeline; 5, medium pressure waste boiler; 6, desalted water heater; 7, low pressure waste boiler; 8, first 4.0MPa nitrogen pipeline; 9, first 4.0MPa nitrogen valve; 10, make-up gas pipeline; 11, make-up gas valve; 12, 3.0MPa air pipeline; 13, 3.0MPa air valve; 14, heat exchanger; 15, first water cooler; 16, compressor low pressure cylinder; 17, second 4.0MPa nitrogen valve; 18, second 4.0MPa nitrogen pipe; 19, two-way one valve; 20, compressor medium pressure cylinder; 21, compressor outlet valve; 22, second water cooler; 23, synthesis gas into cold exchange pipeline; 24, first stage ammonia cooler; 25, cold exchanger; 26, synthesis gas into compressor valve; 27, three-way two valve; 28, compressor high pressure cylinder; 29, compressor steam turbine; 30, second stage ammonia cooler; 31, vent valve; 32, vent pipeline; 33, ammonia separator; 34, ammonia release valve; 35, liquid ammonia storage tank. DETAILED DESCRIPTION
[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.
[0021] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally a class, not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in a "or" relationship.
[0022] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.
[0023] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "arranging" should be understood in a broad sense, for example, can be fixedly connected, arranged, or detachably connected, arranged, or integrally connected, arranged. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.
[0024] Example one:
[0025] A certain chemical fertilizer plant uses the ammonia synthesis catalyst replacement before the temperature reduction oxidation treatment method of the present application to replace the catalyst. First, according to the method requirements, gradually reduce the catalyst temperature to below 250 DEG C, and through the flare system to unload the pressure to the micro-positive pressure state. Subsequently, nitrogen is added to the system for replacement until the NH3 content in the system is ≤0.4%, and the hydrogen content is ≤0.2%. Next, start the synthesis gas compressor to reduce the system temperature, and when the catalyst temperature is reduced to below 150 DEG C, start to gradually add air to the system for oxidation reaction. During the process, the oxygen content and system pressure are strictly controlled to ensure that the catalyst bed temperature does not exceed 350 DEG C. Finally, when the catalyst bed temperature is reduced to below 50 DEG C, the temperature reduction oxidation process is completed, the system is unloaded, and the ammonia synthesis tower is removed. The big cover is successfully completed the replacement of the catalyst.
[0026] The present application uses the existing equipment to add air to the ammonia synthesis device system to perform ammonia synthesis catalyst temperature reduction oxidation treatment; before replacing the catalyst in the ammonia synthesis device, the ammonia synthesis catalyst temperature is reduced to below 250 DEG C, and the hydrogen and nitrogen in the system are unloaded by the flare system; when the pressure is reduced to micro-positive pressure, nitrogen is added to the system; blind plates are installed at the system air supplement valve and the ammonia separator ammonia discharge valve.
[0027] After the above blind plate is installed, the ammonia synthesis tower system is replaced by nitrogen to ensure the safe operation of the cooling oxidation process when the NH3 content in the system is ≦0.4% and the hydrogen content is ≦0.2%; after the system is qualified, the system pressure relief valve is closed, the system is pressurized by nitrogen, and the nitrogen supplement valve is closed when the system pressure rises to 4.0 MPa. Start the synthesis gas compressor to reduce the temperature of the system through the circulation section, and after the catalyst temperature is reduced to below 150℃, supplement air to the system for oxidation reaction, and the catalyst oxidation reaction is carried out at an oxygen content of 0.5%, 1%, 2%, 3%, 5%, 10%, 15, 20% of the system respectively; during the catalyst oxidation cooling process, when the catalyst bed temperature is ≧350℃, stop supplementing air to the system, and when the catalyst temperature is ≦250℃, supplement air; the system pressure is controlled at 4.5-5.5 MPa, and when the system pressure exceeds 5.5 MPa, the system is vented, and part of the gas is discharged to the flare system. When the oxygen content of the system reaches 20%, continuous cooling is carried out, and after the catalyst bed temperature is ≦50℃, the cooling oxidation is completed, the system is depressurized, and the process is handed over, the ammonia synthesis tower large cover is removed, and the preparation work for removing the catalyst in the ammonia synthesis tower is carried out.
[0028] In summary: please refer to Figure 1 In the embodiment of the application, a kind of ammonia synthesis catalyst replacement before cooling oxidation treatment method, including ammonia synthesis tower 2, the bottom of ammonia synthesis tower 2 is fixedly connected with synthesis gas inlet steam superheater pipeline 1, synthesis gas inlet steam superheater pipeline 1 is connected with steam superheater 3, one end of steam superheater 3 is connected with medium pressure waste boiler 5, one end of medium pressure waste boiler 5 is connected with desalted water heater 6, one end of desalted water heater 6 is connected with low pressure waste boiler 7, one end of low pressure waste boiler 7 is connected with heat exchanger 14, one end of heat exchanger 14 is connected with first water cooler 15, one end of first water cooler 15 is connected with second water cooler 22, one end of second water cooler 22 is connected with cold exchange 25, one end of cold exchange 25 is connected with first-stage ammonia cooler 24, one end of first-stage ammonia cooler 24 is connected with second-stage ammonia cooler 30, one end of second-stage ammonia cooler 30 is connected with ammonia separator 33, one end of ammonia separator 33 is connected with liquid ammonia storage tank 35, ammonia separator 33 is connected with ammonia valve 34 near one end of liquid ammonia storage tank 35. Steam superheater 3, medium pressure waste boiler 5, desalted water heater 6, low pressure waste boiler 7, heat exchanger 14, first water cooler 15, second water cooler 22, cold exchange 25, first-stage ammonia cooler 24, second-stage ammonia cooler 30, ammonia separator 33 and liquid ammonia storage tank 35 are connected by pipeline near one end.
[0029] The ammonia synthesis tower 2 is connected with an ammonia synthesis tower inlet pipeline 4 at the top, and the ammonia synthesis tower inlet pipeline 4 is connected with a heat exchanger 14 at the top. The top of the cold exchanger 25 is connected with a synthesis gas inlet cold exchange pipeline 23, and the synthesis gas inlet cold exchange pipeline 23 is connected with a venting pipeline 32 at one end, and the venting pipeline 32 is provided with a venting valve 31. The bottom end of the heat exchanger 14 is connected with a first 4.0 MPa nitrogen pipeline 8, and the first 4.0 MPa nitrogen pipeline 8 is provided with a first 4.0 MPa nitrogen valve 9, and the first 4.0 MPa nitrogen pipeline 8 is connected with a compressor high-pressure cylinder 28 at one end, and the compressor high-pressure cylinder 28 is provided with a compressor outlet valve 21 close to the one end of the first 4.0 MPa nitrogen pipeline 8.
[0030] The one end of the compressor high-pressure cylinder 28 is connected with the bottom of the cold exchanger 25, and the compressor high-pressure cylinder 28 is provided with a synthesis gas inlet compressor valve 26 close to the one end of the cold exchanger 25. The one end of the compressor high-pressure cylinder 28 is connected with a compressor steam turbine 29, and the one end of the compressor high-pressure cylinder 28 is provided with a compressor medium-pressure cylinder 20, and the one end of the compressor medium-pressure cylinder 20 is provided with a compressor low-pressure cylinder 16, and the compressor high-pressure cylinder 28 and the compressor medium-pressure cylinder 20 are in communication with each other, and the compressor medium-pressure cylinder 20 and the compressor low-pressure cylinder 16 are in communication with each other. The three-way two-way valve 27 is arranged between the compressor high-pressure cylinder 28 and the compressor medium-pressure cylinder 20, and the two-way one-way valve 19 is arranged between the compressor medium-pressure cylinder 20 and the compressor low-pressure cylinder 16. The one end of the compressor low-pressure cylinder 16 is connected with a makeup gas pipeline 10, and the makeup gas pipeline 10 is provided with a makeup gas valve 11, and the one end of the makeup gas pipeline 10 is connected with a 3.0 MPa air pipeline 12, and the 3.0 MPa air pipeline 12 is provided with a 3.0 MPa air valve 13, and the makeup gas pipeline 10 is further connected with a second 4.0 MPa nitrogen pipeline 18, and the second 4.0 MPa nitrogen pipeline 18 is provided with a second 4.0 MPa nitrogen valve 17.
[0031] The working principle of the present application is that the two-way one-way valve 19 and the three-way two-way valve 27 are opened, the makeup gas valve 11 is closed, the compressor high-pressure cylinder circulation section is operated, and the catalyst of the ammonia synthesis tower 2 is cooled; the ammonia separator 33 is opened to discharge the liquid ammonia in the ammonia separator 33 to the liquid ammonia storage tank 35; when the temperature of the catalyst of the ammonia synthesis tower 2 is ≤250℃, the compressor outlet valve 21 and the synthesis gas inlet compressor valve 26 are closed, and the compressor motor is stopped. The venting valve 31 is opened to discharge the hydrogen, nitrogen and ammonia in the ammonia synthesis system to the flare system through the venting pipeline 32, and the pressure reduction rate is ≤0.3 MPa / min. When the pressure of the ammonia synthesis system is reduced to 0.05 MPa, the first 4.0 MPa nitrogen valve 9 is slightly opened to supplement nitrogen to the ammonia synthesis system, and the ammonia synthesis system is maintained in a slight positive pressure state.
[0032] Blind plates are installed at the valve 11 and the valve 34 to prevent hydrogen, liquid ammonia and ammonia gas from entering the ammonia synthesis system during the catalyst cooling and oxidation process, thereby affecting the safe operation of the catalyst cooling and oxidation. After the blind plates are installed at the valve 11 and the valve 34, the compressor outlet valve 21 and the synthesis gas inlet compressor valve 26 are opened; the ammonia synthesis system is replaced by adjusting the opening degree of the first 4.0 MPa nitrogen valve 9; when the NH3 content in the ammonia synthesis system is less than or equal to 0.4% and the hydrogen content is less than or equal to 0.2%, the system vent valve is closed, the pressure of the ammonia synthesis system is increased to 4.0 MPa, and the first 4.0 MPa nitrogen valve 9 is closed.
[0033] The start conditions of the compressor turbine 29, the compressor high-pressure cylinder 28, the compressor medium-pressure cylinder 20, the compressor low-pressure cylinder 16, the second return valve 19 and the third return valve 27 are checked, the closed state of the compressor outlet valve 21 and the 3.0 MPa air valve 13 is confirmed, the second 4.0 MPa nitrogen valve 17 is opened, the compressor low-pressure cylinder 16 is charged to ≦1 MPa, the compressor turbine 29 is started and enters the warm-up stage; after the warm-up of the compressor turbine 29 is completed, the number of revolutions of the compressor turbine 29 is controlled at about 7000, the synthesis gas inlet compressor valve 26 is opened, the opening degrees of the second return valve 19 and the third return valve 27 are adjusted according to the compressor surge line; the outlet pressure of the compressor high-pressure cylinder 28 is ≧5.0 MPa, the compressor outlet valve 21 is opened, the ammonia synthesis system is circulated, the circulation gas amount is controlled at 200000 Nm3 / h, the system pressure is controlled at 4.5-5.5 MPa, and when the system pressure exceeds 5.5 MPa, the vent valve 31 is opened for adjustment.
[0034] The 3.0MPa air valve 13 is adjusted by 3%, and the 3.0MPa air passes through the 3.0MPa air pipeline 12, the 3.0MPa air valve 13, the compressor low-pressure cylinder 16, the compressor medium-pressure cylinder 20, the compressor high-pressure cylinder 28, and is mixed with the circulating nitrogen gas, and then enters the ammonia synthesis system through the compressor outlet valve. The oxygen content of the circulating gas at the outlet of the heat exchanger is 0.5%, and the change of the catalyst temperature of the ammonia synthesis tower 2 is observed; when the catalyst bed temperature is greater than or equal to 350 DEG C, the 3.0MPa air valve 13 is closed to stop adding air to the ammonia synthesis system, the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the 3.0MPa air valve 13 is opened by 3% to continue adding air to the ammonia synthesis system; the oxygen content of the circulating gas at the outlet of the heat exchanger is maintained at 0.5%, and when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 1% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 2% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 3% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 5% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 10% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 15% by adjusting the opening of the 3.0MPa air valve 13; when the catalyst temperature of the ammonia synthesis tower 2 is less than or equal to 250 DEG C, the oxygen content of the circulating gas at the outlet of the heat exchanger is adjusted to 20% by adjusting the opening of the 3.0MPa air valve 13; the oxygen content of the circulating gas at the outlet of the heat exchanger is 20%, and the oxidation and cooling of the catalyst temperature of the ammonia synthesis tower 2 is continued.
[0035] After the catalyst bed temperature of the ammonia synthesis tower 2 is less than or equal to 50 DEG C, the cooling and oxidation is completed, the opening of the 3.0MPa air valve 13, the compressor outlet valve 21, and the synthesis gas inlet compressor valve 26 are closed, and the operation of the compressor steam turbine 29 is stopped; the vent valve 31 is opened, the pressure relief rate is less than or equal to 0.3MPa / min, and after the system is depressurized, the process is handed over, the ammonia synthesis tower large cover is removed, and the preparation work for removing the catalyst in the ammonia synthesis tower is performed.
[0036] Operation notes
[0037] 1. The circulating gas amount of the ammonia synthesis system is greater than or equal to 200000Nm3 / h;
[0038] 2. The system pressure is 4.5-5.5MPa;
[0039] 3. The temperature of the catalyst layer of ammonia synthesis tower 2: ≦350℃;
[0040] 4. Matters needing attention when supplementing air:
[0041] 1. The initial system air supplement requires intermittent opening of the 3.0 MPa air valve 13 for 5 minutes, 10 minutes, 20 minutes, 40 minutes, and constant opening.
[0042] 2. During the catalyst cooling and oxidation process of ammonia synthesis tower 2, when the catalyst layer temperature is ≧350℃, close the 3.0 MPa air valve 13, stop supplementing air to the system, and increase the system circulation gas volume to reduce the catalyst layer temperature; when the catalyst temperature is ≦350℃, open the 3.0 MPa air valve 13 and continue to supplement air to the system.
[0043] 3. During the catalyst cooling and oxidation process of ammonia synthesis tower 2, stable operation is required to avoid large fluctuations in system pressure and circulation gas volume, and to prevent catalyst layer temperature from overheating.
[0044] 4. During the catalyst cooling and oxidation process of ammonia synthesis tower 2, if the compressor turbine 29 trips or the circulation water is interrupted, etc., the catalyst cooling and oxidation of ammonia synthesis tower 2 should be stopped immediately, the 3.0 MPa air valve 13 should be closed, and the vent valve 31 should be opened for system pressure reduction treatment; when the system pressure is ≦3.5 MPa, the 4.0 MPa nitrogen valve I 9 should be opened to supplement nitrogen to the system for replacement. And pay attention to the temperature of the catalyst layer of ammonia synthesis tower 2 to prevent overheating accidents.
[0045] 5. During the catalyst cooling and oxidation process of ammonia synthesis tower 2, non-device operators are prohibited from entering the production device; the on-site operators should keep the communication unobstructed.
[0046] It should be noted that in this text, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "includes a" does not exclude the presence of another identical element in the process, method, article or device that includes the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.
[0047] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims.
Claims
1. A method for cooling and oxidizing ammonia synthesis catalyst before replacement, comprising an ammonia synthesis tower (2), characterized in that: The bottom of the ammonia synthesis tower (2) is fixedly connected to a synthesis gas inlet steam superheater pipeline (1), which is connected to a steam superheater (3). One end of the steam superheater (3) is connected to a medium-pressure waste boiler (5), and one end of the medium-pressure waste boiler (5) is connected to a demineralized water heater (6). One end of the demineralized water heater (6) is connected to a low-pressure waste boiler (7), and one end of the low-pressure waste boiler (7) is connected to a heat exchanger (14). One end of the heat exchanger (14) is connected to a first water cooler (15). A second water cooler (22) is connected to one end of a water cooler (15), a cold exchanger (25) is connected to one end of the second water cooler (22), a primary ammonia cooler (24) is connected to one end of the cold exchanger (25), a secondary ammonia cooler (30) is connected to one end of the primary ammonia cooler (24), an ammonia separator (33) is connected to one end of the secondary ammonia cooler (30), a liquid ammonia storage tank (35) is connected to one end of the ammonia separator (33), and an ammonia discharge valve (34) is installed on the pipeline connected to the end of the ammonia separator (33) near the liquid ammonia storage tank (35).
2. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 1, characterized in that: The steam superheater (3), medium-pressure waste boiler (5), demineralized water heater (6), low-pressure waste boiler (7), heat exchanger (14), first water cooler (15), second water cooler (22), cold exchanger (25), primary ammonia cooler (24), secondary ammonia cooler (30), ammonia separator (33) and liquid ammonia storage tank (35) are all connected by pipes at one end of each other.
3. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 1, characterized in that: The top of the ammonia synthesis tower (2) is connected to an ammonia synthesis tower inlet pipeline (4), and one end of the ammonia synthesis tower inlet pipeline (4) is connected to the top of the heat exchanger (14).
4. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 1, characterized in that: The top of the cold exchanger (25) is connected to a syngas inlet cold exchange line (23), and one end of the syngas inlet cold exchange line (23) is connected to a vent line (32), and a vent valve (31) is installed on the vent line (32).
5. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 1, characterized in that: The heat exchanger (14) is connected to a first 4.0MPa nitrogen pipeline (8) at its bottom end. A first 4.0MPa nitrogen valve (9) is provided on the first 4.0MPa nitrogen pipeline (8). A compressor high-pressure cylinder (28) is connected to one end of the first 4.0MPa nitrogen pipeline (8). A compressor outlet valve (21) is provided on the end of the compressor high-pressure cylinder (28) near the first 4.0MPa nitrogen pipeline (8).
6. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 5, characterized in that: One end of the compressor high-pressure cylinder (28) is connected to the bottom of the cold exchanger (25), and a synthesis gas inlet valve (26) is provided at the end of the compressor high-pressure cylinder (28) near the cold exchanger (25).
7. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 5, characterized in that: One end of the compressor high-pressure cylinder (28) is connected to the compressor turbine (29), one end of the compressor high-pressure cylinder (28) is provided with the compressor intermediate-pressure cylinder (20), one end of the compressor intermediate-pressure cylinder (20) is provided with the compressor low-pressure cylinder (16), the compressor high-pressure cylinder (28) and the compressor intermediate-pressure cylinder (20) are interconnected, and the compressor intermediate-pressure cylinder (20) and the compressor low-pressure cylinder (16) are interconnected.
8. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 7, characterized in that: A three-way two-valve (27) is provided between the high-pressure cylinder (28) and the intermediate-pressure cylinder (20) of the compressor, and a two-way one-valve (19) is provided between the intermediate-pressure cylinder (20) and the low-pressure cylinder (16) of the compressor.
9. The method for cooling and oxidizing ammonia synthesis catalyst before replacement according to claim 7, characterized in that: One end of the low-pressure cylinder (16) of the compressor is connected to a supplementary gas pipeline (10), and a supplementary gas valve (11) is provided on the supplementary gas pipeline (10). One end of the supplementary gas pipeline (10) is connected to a 3.0MPa air pipeline (12), and a 3.0MPa air valve (13) is provided on the 3.0MPa air pipeline (12). The supplementary gas pipeline (10) is also connected to a second 4.0MPa nitrogen pipeline (18), and a second 4.0MPa nitrogen valve (17) is provided on the second 4.0MPa nitrogen pipeline (18).