Control device for preventing crystallization of outlet pipeline of hydrolysis reactor
By setting up a water removal structure and a multi-stage heating unit at the outlet of the hydrolysis reactor of the coal-fired unit, the product gas temperature is adjusted in real time, and the problem of pipeline crystallization under low load operation is solved, and the normal and environmentally friendly power generation of the coal-fired unit is achieved.
Patent Information
- Application Number
- CN202421339700.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-12
- Publication Date
- 2025-03-04
- Estimated Expiration
- 2034-06-12
AI Technical Summary
When the coal-fired unit is running at low load, the temperature of the ammonia product exported by the hydrolysis reactor is low, resulting in pipeline crystallization and environmental protection exceeding the standard.
A control device is designed, including a water removal structure at the outlet of the hydrolysis reactor and a multi-stage heating unit arranged along the product gas outlet pipeline. Each stage of the heating unit includes a temperature measuring mechanism, a heater and a temperature adjustment mechanism for adjusting the heating amount in real time according to the temperature of the product gas to prevent the pipeline from crystallizing.
It effectively solves the problem of pipeline crystallization caused by low product gas temperature under low load operation, and ensures the normal and environmentally friendly power generation of coal-fired units under deep peak-shaving state.
Smart Images
Figure CN222550571U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of coal-fired power unit equipment, specifically to a control device for preventing crystallization in the outlet pipe of a hydrolysis reactor. Background Technology
[0002] Currently, under special conditions such as low wind, dry season, and rainy days, new energy sources cannot guarantee a stable output of electricity. In such cases, relatively stable thermal power plants must continue to fulfill their power generation mission through deep peak shaving.
[0003] The ideal operating range for ammonia production in the hydrolysis reactor of a coal-fired power unit is 50% to 100% of its rated output. However, due to the large seasonal and diurnal variations in grid load, especially during the wet season and at night, coal-fired power units are in a state of deep peak shaving for a long time, and the hydrolyzer is in an ultra-low load range (20%-50%) for a long time. The temperature of the ammonia gas produced in the hydrolysis reactor is about 110-130℃, which is lower than the normal product gas outlet temperature requirement. Especially in winter, ammonia pipelines are prone to crystallization. After crystallization, the ammonia gas cannot be sent into the SCR reactor in time, which can easily cause environmental pollution exceeding the standard. Utility Model Content
[0004] This utility model aims to provide a control device to prevent crystallization in the outlet pipeline of a hydrolysis reactor, in order to solve the environmental problem of excessive emissions caused by crystallization in the pipeline due to the low temperature of ammonia product gas at the outlet of the hydrolysis reactor under low load of coal-fired units.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: a control device for preventing crystallization in the outlet pipe of a hydrolysis reactor, comprising a water removal structure installed at the outlet of the hydrolysis reactor and a multi-stage heating unit installed along the product gas outlet pipe. Each stage of the heating unit includes a temperature measuring mechanism, a heater, and a temperature regulating mechanism. The heater has an inlet and an outlet, and the inlet and outlet are respectively connected to an inlet pipe and an outlet pipe. The inlet pipe and the outlet pipe are respectively used to transport the heating medium before and after heat exchange with the product gas. The temperature measuring mechanism is used to detect the temperature of the product gas at the input end of the heater, and the temperature regulating mechanism is used to adjust the amount of heating medium transported in the heater according to the product gas temperature measured by the temperature measuring mechanism.
[0006] The principle behind this solution is:
[0007] In practical applications, urea reacts in the hydrolysis reactor to generate product gas, which is then transported to the SCR reactor via the product gas outlet pipe. During transport, it passes through a dehydration structure and multiple heating units. The dehydration structure reduces the water vapor content in the product gas, preventing heat loss and ammonia crystallization during subsequent transport. The product gas then passes through each heating unit. Upon entering each heating unit, the temperature is measured by a temperature measuring device and compared with the normal product gas outlet temperature to determine whether heating is required in that heating unit. If no heating is needed, the product gas continues to the next heating unit. If the measured temperature is lower than the normal product gas outlet temperature, heating is required, the temperature regulating mechanism is activated, and the heating medium enters the heater to begin heating the product gas. After the heating medium's temperature decreases, it is recovered via the outlet pipe.
[0008] Beneficial effects:
[0009] 1. In this solution, a water removal structure and a heating unit are sequentially installed on the product gas outlet pipeline. This not only reduces the water content of the product gas, but also heats the product gas during transportation. For hydrolysis reactors operating in the ultra-low load range (20%-50%), this effectively solves the problem of crystallization in the outlet pipeline caused by the product gas temperature being lower than the normal product gas temperature, which prevents the timely transportation of product gas. This ensures that the coal-fired unit can generate electricity normally and in an environmentally friendly manner under deep peak shaving conditions.
[0010] 2. This solution includes multiple heating units along the product gas conveying direction to ensure that the product gas is heated in different pipeline areas during the conveying process. Because the outlet pipeline for conveying the product gas is very long, if a heating unit is set up in only one place, some product gas may crystallize before it is heated or crystallize during subsequent conveying. At the same time, to avoid resource waste or overheating of the product gas caused by heating in every heating unit, each heating unit includes a temperature measuring mechanism and a temperature regulating mechanism. The temperature regulating mechanism is used to adjust the conveying amount of heating medium in the heater according to the product gas temperature measured by the temperature measuring mechanism, thereby controlling the amount of heating medium conveyed to ensure the heating temperature of the product gas, achieving automated control, precise production, and saving production costs.
[0011] Furthermore, the heating unit has no more than three stages.
[0012] Too many heating unit stages will increase equipment costs. Whether each heating unit stage is activated to heat the product gas depends on the temperature of the product gas before it enters the heating unit stage. Too many heating unit stages result in the heating units being too close together, and some heating units will not be able to function for a long time, resulting in wasted resources. Controlling the number of heating unit stages to three or less can prevent the product gas from crystallizing during transportation and save enterprise costs.
[0013] Furthermore, the heater is a surface steam heater, which includes an outer shell and a heat exchange tube disposed inside the outer shell. The inlet and outlet are disposed on the outer shell, and the direction from the inlet to the outlet is opposite to the product gas conveying direction. The two ends of the heat exchange tube pass through the outer shell and are connected to the inlet pipe and the outlet pipe, respectively.
[0014] In the above setup, the heating medium is heating steam. The direction from the inlet to the outlet is opposite to the direction of the product gas delivery, which causes countercurrent heat exchange between the heating steam and the product gas, increasing the temperature difference between the two gases. This results in more uniform heating inside the product gas and higher heat exchange efficiency.
[0015] Furthermore, the heat exchange tube is spirally wound around the product gas outlet pipe, with a pitch of 1.2 to 2 times the diameter of the heat exchange tube.
[0016] Setting the pitch of the heat exchange tube within the above range serves two purposes: first, to increase the heat exchange contact area between the heating steam and the heat exchange tube, ensuring sufficient heat exchange for heating the product gas and improving heat exchange efficiency; and second, to avoid excessive flow resistance of the heating steam when it flows in the heat exchange tube due to an excessively large pitch, thereby reducing heat loss and improving heat exchange efficiency.
[0017] Furthermore, the temperature regulating mechanism includes a temperature regulating valve and a manual door in front of the regulating valve and a manual door behind the regulating valve installed on both sides of the temperature regulating valve.
[0018] The purpose of the manual valves before and after the regulating valve in the above settings is to adjust the steam flow or close the inlet pipe by operating the manual valves before and after the regulating valve when the temperature regulating valve fails, so as to achieve safe and smooth heating of the product gas.
[0019] Furthermore, the product gas outlet pipeline is provided with a bypass pipeline connected to the temperature regulating valve, and a bypass regulating valve is installed on the bypass pipeline.
[0020] The function of the aforementioned bypass pipe and bypass regulating valve is to ensure that the heating unit can smoothly heat the product gas when the temperature regulating valve is blocked.
[0021] Furthermore, the outer shell is provided with an insulation layer, and sealing rings are provided at the inlet and outlet.
[0022] The above settings are to prevent heat loss from the outer casing, which would result in low heat exchange efficiency between the product gas and the heating steam. Attached Figure Description
[0023] Figure 1 This is a structural schematic diagram of an embodiment of the present utility model.
[0024] Figure 2for Figure 1 A schematic diagram of part A in the diagram.
[0025] Figure 3 This is a simplified structural diagram of a surface steam heater according to an embodiment of the present invention. Detailed Implementation
[0026] The following detailed description illustrates the specific implementation method:
[0027] The reference numerals in the accompanying drawings include: 1. Hydrolysis reactor; 2. Product gas outlet pipe; 3. Water removal structure; 4. Heating unit; 41. Temperature measuring mechanism; 42. Surface steam heater; 421. Outer shell; 422. Heat exchange tube; 43. Temperature regulating mechanism; 431. Temperature regulating valve; 432. Manual valve before regulating valve; 433. Manual valve after regulating valve; 44. Bypass pipe; 45. Bypass regulating valve; 5. Steam supply device; 6. Drain collection device; 61. Drain valve; 62. Drain tank; 7. Inlet pipe; 8. Outlet pipe.
[0028] The basic details of the implementation example are attached. Figure 1-3As shown: A control device for preventing crystallization in the outlet pipe of a hydrolysis reactor includes a dewatering structure 3 installed at the outlet of the hydrolysis reactor 1 and a multi-stage heating unit 4 installed along the product gas outlet pipe 2. The number of stages of the heating unit 4 does not exceed three. Preferably, in this embodiment, there are two stages of heating unit 4. Both stages of heating unit 4 are sequentially installed on the product gas outlet pipe 2 between the dewatering structure 3 and the SCR reactor. Each stage of heating unit 4 includes a temperature measuring mechanism 41, a heater, and a temperature regulating mechanism 43. In this embodiment, the heater is preferably a surface steam heater 42. The heating medium in the surface steam heater 42 is heating steam. After the heating steam exchanges heat with the product gas, its temperature decreases, forming condensate. The temperature measuring mechanism 41 and the surface steam heater 42 are sequentially arranged on the product gas conveying pipeline 2 along the product gas conveying direction, and the temperature regulating mechanism 43 is installed on the inlet pipeline 7. The surface steam heater 42 is provided with an inlet and an outlet, and the inlet and outlet are respectively connected to the inlet pipeline 7 and the outlet pipeline 8. The inlet pipeline and the outlet pipeline are respectively connected to the steam supply device 5 for conveying heating steam and the condensate collection device 6 for conveying condensate. The temperature measuring mechanism 41 is used to detect the product gas temperature at the input end of the surface steam heater 42, and the temperature regulating mechanism 43 is used to adjust the amount of steam conveyed in the surface steam heater 42 according to the product gas temperature measured by the temperature measuring mechanism 41. Both the temperature measuring mechanism 41 and the temperature regulating mechanism 43 are connected to the DCS control system. The DCS control system has a preset temperature range of 135 to 160°C. When the product gas flows through the heating unit 4, the temperature measuring mechanism 41 first measures the temperature of the product gas and compares it with the preset temperature range. If the product gas temperature is within this temperature range, the heating unit 4 at this stage will not start, and the product gas will continue to be delivered to the next heating unit 4. If the product gas temperature is lower than this temperature range, the DCS control system controls the temperature regulating mechanism 43 to start, and the heating steam enters the surface steam heater 42 to start heating the product gas.
[0029] like Figure 2 As shown, the temperature regulating mechanism 43 includes a temperature regulating valve 431. The temperature regulating valve 431 is provided with a manual valve 432 before the regulating valve and a manual valve 433 after the regulating valve on both sides. This ensures that when the temperature regulating valve 431 fails, the steam flow can be adjusted or the inlet pipe 7 can be closed by operating the manual valve 432 before the regulating valve and the manual valve 433 after the regulating valve. The temperature regulating valve 431 is also provided with a bypass pipe 44 connected to the inlet pipe 7. A bypass regulating valve 45 is provided on the bypass pipe 44. When the temperature regulating valve 431 is blocked, the bypass pipe 44 serves as a backup passage to ensure that the heating unit 4 can smoothly heat the product gas.
[0030] like Figure 3As shown, the surface steam heater 42 includes a housing 421 and a heat exchange tube 422 disposed within the housing 421. The housing 421 has an inlet and an outlet, and the direction from the inlet to the outlet is opposite to the product gas conveying direction. Specifically, in this embodiment, the outlet and the inlet are respectively located at the upper left and lower right of the housing 421. The two ends of the heat exchange tube 422 are connected to the inlet pipe 7 and the outlet pipe 8, respectively, to achieve countercurrent heat conduction between the heating steam and the product gas, thereby improving the heat exchange efficiency. The heat exchange tube 422 is spirally wound around the product gas outlet pipe 2, and adjacent spirals are wound in a spiral shape. The pitch between the spirals is 1.2 to 2 times the diameter of the heat exchange tube. Within this pitch range, the heating steam can have a large heat exchange contact area in the heat exchange tube 422, and the flow resistance of the heating steam in the heat exchange tube 422 can be reduced, thereby reducing heat loss and improving heat exchange efficiency. The outer shell 421 is covered with an insulation layer (not shown in the figure). The insulation layer is made of heat-insulating material. A sealing ring (not shown in the figure) is provided between the inlet and the inlet pipe 7 and between the outlet and the outlet pipe 8. The sealing ring is made of heat-insulating material to prevent heat loss inside the outer shell 421 and low product gas heating efficiency.
[0031] In this embodiment, the water removal structure 3, the steam supply device 5, the method by which the water removal structure 3 removes water vapor from the product gas, the method by which the steam supply device 5 provides steam, and the method by which the DCS control system controls the temperature regulation mechanism 43 are all existing technologies and will not be described in detail here. The condensate collection device 6 includes a condensate valve 61 and a condensate tank 62. A check valve (not shown in the figure) is also provided between the condensate tank 62 and the condensate valve 61 to prevent condensate backflow from damaging the condensate valve 61.
[0032] The specific implementation process is as follows:
[0033] In practical applications, urea reacts in the hydrolysis reactor 1 to generate product gas, which is then transported to the SCR reactor via the product gas outlet pipe 2. During transport, it passes sequentially through the dehydration structure 3 and the heating unit 4. Passing through the dehydration structure 3 reduces the water vapor content in the product gas, preventing heat loss and ammonia crystallization during subsequent transport. The product gas then passes through each stage of the heating unit 4. Upon entering each stage of the heating unit 4, the temperature of the product gas is measured by the temperature measuring mechanism 41 and compared with a predetermined temperature range. If the product gas temperature falls within this range, the heating unit 4 does not... Upon startup, the product gas continues to be delivered to the next heating unit 4. If the product gas temperature is lower than this temperature range, the DCS control system calculates the opening degree of the temperature regulating valve 431 based on the temperature difference between the product gas temperature and the set temperature range, and controls the temperature regulating valve 431 to open to this degree. The heating steam enters the surface steam heater 42 through the inlet pipe 7, and heats the product gas to the set temperature range through the spirally wound heat exchange tube 422. After the heat exchange is completed, the temperature of the heating steam decreases, forming condensate that flows into the condensate tank 62 along the outlet pipe 8 for recycling.
[0034] The above descriptions are merely embodiments of this utility model. Commonly known technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A control device for preventing crystallization of a hydrolysis reactor outlet pipe, characterized in that: It includes a water removal structure arranged at the outlet of the hydrolysis reactor and a multi-stage heating unit arranged along the product gas outlet pipeline. Each stage of the heating unit includes a temperature measuring mechanism, a heater and a temperature regulating mechanism. The heater is provided with an inlet and an outlet, and the inlet and the outlet are respectively connected with an inlet pipeline and an outlet pipeline, which are respectively used to transport the heating medium before and after heat exchange with the product gas; the temperature measuring mechanism is used to detect the product gas temperature at the input end of the heater, and the temperature regulating mechanism is used to adjust the delivery amount of the heating medium in the heater according to the product gas temperature measured by the temperature measuring mechanism.
2. A control device for preventing crystallization of a hydrolysis reactor outlet pipeline according to claim 1, characterized in that: The number of stages of the heating units does not exceed three.
3. A control device for preventing crystallization of a hydrolysis reactor outlet pipeline according to claim 2, characterized in that: The heater is a surface steam heater, which includes an outer shell and a heat exchange tube arranged inside the outer shell. The inlet and the outlet are arranged on the outer shell. The direction from the inlet to the outlet is opposite to the product gas conveying direction. Both ends of the heat exchange tube pass through the outer shell and are connected with the inlet pipe and the outlet pipe respectively.
4. A control device for preventing crystallization of a hydrolysis reactor outlet pipeline according to claim 3, characterized in that: The heat exchange tube is wound around the product gas outlet pipeline in a spiral form, wherein the pitch is 1.2 to 2 times the diameter of the heat exchange tube.
5. A control device for preventing crystallization of a hydrolysis reactor outlet pipe according to claim 4, characterized in that: The temperature regulating mechanism comprises a temperature regulating valve and a front manual door and a rear manual door installed on both sides of the temperature regulating valve.
6. A control device for preventing crystallization of a hydrolysis reactor outlet pipe according to claim 5, characterized in that: The product gas outlet pipeline is provided with a bypass pipeline in communication with the temperature regulating valve at the temperature regulating valve, and a bypass regulating valve is installed on the bypass pipeline.
7. A control device for preventing crystallization of a hydrolysis reactor outlet pipe according to claim 6, characterized in that: The outer shell is provided with a heat-insulating layer, and sealing rings are provided at the inlet and the outlet.