Novel low-temperature coal economizer for realizing deliming by utilizing electric heating

Abstract

The utility model relates to the technical field of waste heat recovery of coal-fired power plants, in particular to a novel low-temperature coal economizer capable of realizing deashing by utilizing electric heating, which comprises a top steam-water heat exchanger, a water inlet header is communicated with the inside of the top steam-water heat exchanger, and a water inlet pipeline is communicated with the inside of the water inlet header. The interior of the top steam-water heat exchanger communicates with a water outlet collecting box, and the interior of the water outlet collecting box communicates with a water outlet pipeline. The utility model solves the problems that as most low-temperature coal economizers in coal-fired power plants use finned tubes, as heat medium water is directly introduced into heat exchange tubes and directly leaks into a flue after the heat exchange tubes are abraded, ammonium bisulfate generated in the denitration process is adhered to the surfaces of the heat exchange plates, fly ash in flue gas is adsorbed and gathered, the coal economizers are blocked, and the heat exchange tubes are damaged. Therefore, a serious ash deposition phenomenon is generated, the normal operation of a boiler flue gas and air system is influenced, and even the boiler system is stopped and the operation safety is poor.

Description

Technical Field

[0001] The utility model relates to the technical field of waste heat recovery in coal-fired power plants, in particular to a novel low-temperature economizer that realizes ash removal by electric heating. Background Technique

[0002] A low-temperature economizer is a device that can effectively save coal and improve the boiler efficiency in the low-temperature section. It is mainly applied to the middle and low-temperature sections at the outlet of the air preheater of large boilers such as power plants and thermal power plants. By recovering the waste heat of the flue gas to heat the boiler feed water, the exhaust gas heat efficiency can be effectively reduced. The low-temperature economizer is usually installed in the tail flue at the outlet of the boiler air preheater. It can not only improve the electric dust removal efficiency and meet the low-emission requirements, but also reduce the power consumption, reduce the specifications of downstream equipment, and remove most of the acidic gases at the same time.

[0003] During the SCR denitration process, there is ammonia escape, which reacts with the incompletely combusted product SO3 to generate ammonium bisulfate (ABS). The melting point of ABS is 147°C and the boiling point is 350°C. It exists in the flue gas in solid and liquid forms, and at the same time has strong viscosity and adsorption. It is extremely easy to adhere to the low-temperature economizer, agglomerate fly ash, and cause blockage. Most of the existing low-temperature economizers in coal-fired power plants use finned tubes. Since the heat transfer medium water directly enters the heat exchange tubes, after the heat exchange tubes are worn, the heat transfer medium water will directly leak into the flue gas, causing the ammonium bisulfate generated during the denitration process to adhere to the surface of the heat exchange plate, and the fly ash in the flue gas is adsorbed and aggregated, resulting in the blockage of the economizer, and then serious ash accumulation phenomenon occurs, affecting the normal operation of the boiler flue gas and air system, and even causing the boiler system to shut down, with poor operation safety.

[0004] Therefore, the utility model provides a novel low-temperature economizer that realizes ash removal by electric heating. Content of the Utility Model

[0005] The purpose of the utility model is to solve the disadvantages that most of the low-temperature economizers in coal-fired power plants in the prior art use finned tubes. Since the heat transfer medium water directly enters the heat exchange tubes, after the heat exchange tubes are worn, the heat transfer medium water will directly leak into the flue gas, causing the ammonium bisulfate generated during the denitration process to adhere to the surface of the heat exchange plate, and the fly ash in the flue gas is adsorbed and aggregated, resulting in the blockage of the economizer, and then serious ash accumulation phenomenon occurs, affecting the normal operation of the boiler flue gas and air system, and even causing the boiler system to shut down, with poor operation safety, and a novel low-temperature economizer that realizes ash removal by electric heating is proposed.

[0006] To achieve the above object, the utility model adopts the following technical solutions: A new type of low-temperature economizer that uses electric heating to achieve ash removal, including an inlet header, an inlet pipe connected to the inlet header and installed on a sealed box body, an outlet header, an inlet pipe connected to the outlet header and installed on the sealed box body, a plurality of pipes located inside the top steam-water heat exchanger and communicating with the inlet header and the outlet header, a plurality of heat exchange fins arranged at equal intervals inside the wide-channel heat exchanger, a lower heat medium water tank located below the heat exchange fins and a water collection tank located above, a downcomer connecting the heat medium water tank and the water collection tank, an electric heating pipe for electric heating in the heat medium water tank, a pressure gauge and a pressure relief valve at the top of the equipment.

[0007] The effects achieved by the cooperation of the above components are as follows: The function of the bottom electric heating is to heat the heat exchange plate to a specified temperature, and the ammonium bisulfate adhered to the heat exchange plate will sublime / vaporize and be carried away by the flue gas, realizing the removal of ammonium bisulfate, effectively promoting the volatilization of ABS in the economizer, reducing the probability of system blockage and ash accumulation, thus effectively reducing the phenomenon of blockage and ash accumulation and enhancing the operation stability of the system.

[0008] Preferably, a sleeve is sleeved on the surface of the inlet pipe, a rotating rod is rotatably inserted inside the sleeve, a rotating frame is fixedly installed on the surface of the rotating rod, a connecting plate is fixedly installed on the surface of the rotating frame, a sealing gasket is fixedly installed at one end of the connecting plate close to the inlet pipe, and the surface of the sealing gasket abuts against the inlet pipe.

[0009] The effects achieved by the above components are as follows: When the economizer is not in use, the sealing gasket can block the port of the inlet pipe, so that sundries cannot enter the inside of the economizer through the inlet pipe.

[0010] Preferably, an extrusion cylinder is threadedly connected to the surface of the rotating rod, and the surface of the extrusion cylinder abuts against the sleeve.

[0011] The effects achieved by the above components are as follows: Rotate the extrusion cylinder, and the extrusion cylinder moves in the direction close to the sleeve by means of the thread. After the extrusion cylinder moves a certain distance, the surface of the extrusion cylinder presses the sleeve. At this time, the rotating rod and the sleeve are fixed, and the sealing gasket and the sleeve are also fixed.

[0012] Preferably, four mounting rods are fixedly inserted inside the extrusion cylinder, and the four mounting rods are evenly distributed on the surface of the extrusion cylinder.

[0013] The effects achieved by the above components are as follows: Rotate the mounting rod, and the mounting rod drives the extrusion cylinder to rotate while rotating, achieving the effect of driving the extrusion cylinder to rotate.

[0014] Preferably, the cross-section of the rotating frame is in an "L" shape, and anti-slip protrusions are provided on the surface of the rotating frame.

[0015] The effects achieved by the above components are as follows: The anti-slip protrusions can assist the staff in rotating the rotating frame.

[0016] In summary:

[0017] In the present utility model, when using the low-temperature economizer, the first step: The waste heat flue gas at the outlet of the air preheater passes through the wide-flow channel heat exchange plate, transferring the waste heat to the heat exchange fins. The second step: The heat medium medium self-circulation system: After the heat medium water exchanges heat in the wide-channel heat exchanger, it becomes a steam-water mixture and rises until it turns into steam and enters the top header. After the steam exchanges heat with the top heat exchanger, it condenses, and the steam becomes condensed water droplets, which flow back to the water collection tank through the inclined plate at the lower part of the top header. The heat medium water in the water collection tank uses the density difference and returns to the bottom header under the action of gravity through the downcomer. The water in the heat medium water tank enters the heat exchange plate for heating under the combined action of the density difference between the downcomer and the heat plate, the upward force of the bubbles on the heat plate, and part of the capillary condensation liquid film force. Since then, the heat medium water forms a self-circulation. The third step: After the boiler condensate passes through the top heat exchanger, it is heated and directly returns to the condensate outlet pipe. Since the boiler condensate pipe does not contact the flue gas and only exchanges heat with the top steam, there is no risk of leakage, and zero leakage of the boiler condensate can be achieved. Cleaning ABS: Turn on the electric heating tube to heat the heat medium water. The temperature of the heat medium water rises and evaporates into steam. Since the system is completely closed, the evaporated steam pressurizes the entire sealed system, continuously increasing the boiling point of the heat medium water. Control the electric heating time and temperature according to the pressure gauge index. When the temperature reaches 360 °C, maintain this temperature. When the temperature of the heat exchange plate reaches the temperature at which ABS can volatilize, the gaseous ABS is carried away by the flue gas, thereby achieving the cleaning of ABS. The effects achieved by the mutual cooperation of the above components are as follows: The function of the bottom electric heating is to heat the heat exchange plate to the specified temperature. The ammonium bisulfate adhered to the heat exchange plate will sublime / vaporize and be carried away by the flue gas, achieving the removal of ammonium bisulfate, effectively promoting the volatilization of ABS in the economizer, reducing the probability of system blockage and ash accumulation, thereby effectively reducing the blockage and ash accumulation phenomenon and enhancing the operation stability of the system. Description of the Drawings

[0018] Figure 1 It is a three-dimensional structural schematic diagram of the present utility model;

[0019] Figure 2 It is a structural schematic diagram at the water inlet pipe of the present utility model.

[0020] Legend: 1. Water inlet pipe; 2. Water inlet header; 3. Water outlet pipe; 4. Water outlet header; 5. Top steam-water heat exchanger; 6. Steam relief valve; 7. Pressure gauge; 8. Water collection tank; 9. Plate heat exchange fin; 10. Bottom heat medium water tank; 11. Electric heating tube; 12. Downcomer; 13. Sleeve; 14. Extrusion cylinder; 15. Mounting rod; 16. Rotating rod; 17. Rotating frame; 18. Connecting plate; 19. Sealing gasket. Detailed Embodiment

[0021] Referring to Figure 1-2 as shown in the figure, the utility model provides a technical solution: a new type of low-temperature economizer for ash removal by electric heating, which includes a top steam-water heat exchanger 5. An inlet water header 2 is connected to the inside of the top steam-water heat exchanger 5. An inlet water pipe 1 is connected to the inside of the inlet water header 2. An outlet water header 4 is connected to the inside of the top steam-water heat exchanger 5. An outlet water pipe 3 is connected to the inside of the outlet water header 4. A number of pipes are connected to the inside of the top steam-water heat exchanger 5. A number of plate heat exchange fins 9 are evenly arranged inside the top steam-water heat exchanger 5. A bottom heat medium water tank 10 is installed on the surface of the number of plate heat exchange fins 9. A water collecting tank 8 is installed on the surface of the number of heat exchange fins. A downcomer 12 is connected to the inside of the bottom heat medium water tank 10. The inside of the downcomer 12 is connected to the water collecting tank 8. An electric heating pipe 11 is installed inside the bottom heat medium water tank 10. A pressure gauge 7 is connected to the inside of the top steam-water heat exchanger 5. A steam relief valve 6 is connected to the inside of the top steam-water heat exchanger 5. The effects achieved by the cooperation of the above components are as follows: the function of the bottom electric heating is to heat the heat exchange plate to a specified temperature, and the ammonium bisulfate adhered to the heat exchange plate will sublimate / vaporize and be carried away by the flue gas, realizing the removal of ammonium bisulfate, effectively promoting the volatilization of ABS in the economizer, reducing the probability of system blockage and ash accumulation, thereby effectively reducing the phenomenon of blockage and ash accumulation and enhancing the operation stability of the system. A sleeve 13 is sleeved on the surface of the inlet water pipe 1. A rotating rod 16 is rotatably inserted into the inside of the sleeve 13. A rotating frame 17 is fixedly installed on the surface of the rotating rod 16. A connecting plate 18 is fixedly installed on the surface of the rotating frame 17. A sealing gasket 19 is fixedly installed at one end of the connecting plate 18 close to the inlet water pipe 1. The surface of the sealing gasket 19 abuts against the inlet water pipe 1. When the economizer is not in use, the sealing gasket 19 can block the port of the inlet water pipe 1, so that sundries cannot enter the inside of the economizer through the inlet water pipe 1. A pressing cylinder 14 is threadedly connected to the surface of the rotating rod 16. The surface of the pressing cylinder 14 abuts against the sleeve 13. By rotating the pressing cylinder 14, the pressing cylinder 14 moves in the direction close to the sleeve 13 by means of the thread. After the pressing cylinder 14 moves a certain distance, the surface of the pressing cylinder 14 presses the sleeve 13. At this time, the rotating rod 16 and the sleeve 13 are fixed, and the sealing gasket 19 and the sleeve 13 are also fixed. Four mounting rods 15 are fixedly inserted into the inside of the pressing cylinder 14. The four mounting rods 15 are evenly distributed on the surface of the pressing cylinder 14. By rotating the mounting rod 15, the pressing cylinder 14 is driven to rotate while the mounting rod 15 rotates, achieving the effect of driving the pressing cylinder 14 to rotate. The cross-section of the rotating frame 17 is in an "L" shape, and anti-slip protrusions are provided on the surface of the rotating frame 17. The anti-slip protrusions can assist the staff to rotate the rotating frame 17.

[0022] Working principle: When using a low-temperature economizer, the first step is that the waste heat flue gas at the outlet of the air preheater passes through the wide-flow channel heat exchange plate and transfers the waste heat to the heat exchange fins. The second step is the self-circulation system of the heat transfer medium: After the heat transfer medium water exchanges heat in the wide-channel heat exchanger, it becomes a steam-water mixture and rises until it turns into water vapor and enters the top header. After the water vapor exchanges heat with the top heat exchanger and condenses, the water vapor becomes condensed water droplets and flows back to the water collection tank 8 through the inclined plate at the lower part of the top header. The heat transfer medium water in the water collection tank 8 uses the density difference and returns to the bottom header under the gravity of the downcomer 12. The water in the heat transfer medium water tank enters the heat exchange plate for heating under the combined action of the density difference between the downcomer 12 and the heat plate, the upward force of the bubbles on the heat plate, and the partial capillary condensation liquid film force. Thus, the heat transfer medium water forms a self-circulation. The third step is that after the boiler condensate passes through the top heat exchanger, it is heated and directly returns to the condensate outlet pipe. Since the boiler condensate pipe does not contact the flue gas and only exchanges heat with the top water vapor, there is no risk of leakage, and zero leakage of the boiler condensate can be achieved. Cleaning ABS: Turn on the electric heating tube 11 to heat the heat transfer medium water. The temperature of the heat transfer medium water rises and evaporates into water vapor. Since the system is completely closed, the evaporated water vapor pressurizes the entire sealed system, continuously increasing the boiling point of the heat transfer medium water. Control the electric heating time and temperature according to the index of the pressure gauge 7. When the temperature reaches 360 °C, maintain this temperature. When the temperature of the heat exchange plate reaches the temperature at which ABS can volatilize, the gaseous ABS is carried away by the flue gas, thereby achieving the cleaning of ABS. The effects achieved by the cooperation of the above components are as follows: The function of the bottom electric heating is to heat the heat exchange plate to the specified temperature, and the ammonium bisulfate adhered to the heat exchange plate will sublime / vaporize and be carried away by the flue gas, realizing the removal of ammonium bisulfate, effectively promoting the volatilization of ABS in the economizer, reducing the probability of system blockage and ash accumulation, thereby effectively reducing the phenomenon of blockage and ash accumulation and enhancing the operation stability of the system.

[0023] In the description of the present invention, it should be noted that 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 a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

Claims

1. A novel low-temperature economizer for ash removal using electric heating, comprising a top steam-water heat exchanger (5), characterized in that: The interior of the top steam-water heat exchanger (5) is connected to a water inlet header (2), the interior of the water inlet header (2) is connected to a water inlet pipe (1), the interior of the top steam-water heat exchanger (5) is connected to a water outlet header (4), the interior of the water outlet header (4) is connected to a water outlet pipe (3), the interior of the top steam-water heat exchanger (5) is connected to a number of pipes, a number of plate heat exchange fins (9) are evenly arranged inside the top steam-water heat exchanger (5), a bottom heat medium water tank (10) is installed on the surfaces of the number of plate heat exchange fins (9), a water collecting tank (8) is installed on the surfaces of the number of heat exchange fins, a downcomer (12) is connected to the interior of the bottom heat medium water tank (10), the interior of the downcomer (12) is connected to the water collecting tank (8), an electric heating pipe (11) is installed inside the bottom heat medium water tank (10), a pressure gauge (7) is connected to the interior of the top steam-water heat exchanger (5), and a steam relief valve (6) is connected to the interior of the top steam-water heat exchanger (5).

2. The novel low-temperature economizer for ash removal using electric heating according to claim 1, wherein: A sleeve (13) is sleeved on the surface of the water inlet pipe (1), a rotating rod (16) is rotatably inserted into the interior of the sleeve (13), a rotating bracket (17) is fixedly installed on the surface of the rotating rod (16), a connecting plate (18) is fixedly installed on the surface of the rotating bracket (17), a sealing gasket (19) is fixedly installed at one end of the connecting plate (18) close to the water inlet pipe (1), and the surface of the sealing gasket (19) abuts against the water inlet pipe (1).

3. The novel low-temperature economizer for ash removal by using electric heating according to claim 2, characterized in that: An extrusion cylinder (14) is threadedly connected to the surface of the rotating rod (16), and the surface of the extrusion cylinder (14) abuts against the sleeve (13).

4. A novel low-temperature economizer for ash removal using electric heating according to claim 3, characterized in that: Four mounting rods (15) are fixedly inserted into the interior of the extrusion cylinder (14), and the four mounting rods (15) are evenly distributed on the surface of the extrusion cylinder (14).

5. A novel low-temperature economizer for ash removal using electric heating according to claim 2, characterized in that: The cross-section of the rotating bracket (17) is in an "L" shape, and anti-slip protrusions are provided on the surface of the rotating bracket (17).

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