Energy-saving system for improving secondary air temperature in wet operation of once-through boiler

Abstract

The invention discloses a once-through boiler wet operation secondary air temperature increasing energy-saving system which comprises a water storage tank, the water storage tank is connected with an atmosphere type flash tank and a secondary air heater through pipelines, the atmosphere type flash tank is connected with a water collecting tank through a pipeline, and the water collecting tank is connected with a deaerator, a unit drainage groove and an air machine drainage groove through pipelines. The secondary air heater is sequentially connected with an air feeder, a silencer and an inlet filter screen. According to the once-through boiler wet operation secondary air temperature increasing energy-saving system, the problems that in the prior art, most boilers are not provided with boiler water circulating pumps, a large amount of working media and heat are discharged, and unit energy consumption is further increased are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of boiler working fluids and heat recovery devices, and in particular relates to an energy-saving system for increasing the secondary air temperature of a direct-current boiler during wet operation. Background Art

[0002] With the continuous investment in new energy sources in the country, the utilization hours of thermal power units in power station boilers are getting lower and lower. All power plants are carrying out different depths of peak regulation and start-stop peak regulation, and the depth of peak regulation is getting lower and lower. Some direct current boilers are difficult to maintain dry operation and must be switched to wet operation. Since most boilers are not equipped with boiler water circulation pumps, a large amount of working fluid and heat are discharged, and the energy consumption of the units is further increased. Summary of the invention

[0003] The purpose of the present invention is to provide an energy-saving system for improving the secondary air temperature of a direct current boiler during wet operation, which solves the problem that most boilers in the prior art are not equipped with a boiler water circulation pump, resulting in a large amount of working fluid and heat being discharged, and the energy consumption of the unit being further increased.

[0004] The technical solution adopted by the present invention is that the energy-saving system for increasing the secondary air temperature of a direct current boiler in wet operation includes a water storage tank, which is respectively connected to an atmospheric expansion tank and a secondary air heater through pipelines, the atmospheric expansion tank is connected to a water collecting tank through pipelines, the water collecting tank is respectively connected to a deaerator, a unit drainage trough and an air machine expansion through pipelines, and the secondary air heater is sequentially connected to a blower, a muffler and an inlet filter. The technical solution adopted by the present invention is also characterized in that: Furthermore, both sides of the water tank are connected to an A-side self-starting separator and a B-side self-starting separator through pipelines respectively.

[0005] Furthermore, the water tank is connected to three parallel branch pipes G1, branch pipe G2 and branch pipe G3 through pipe G0. Branch pipe G1 is connected to the secondary air heater. Branch pipe G2 and branch pipe G3 are both connected to the atmospheric expansion tank. A pneumatic regulating door v-3 is arranged on the main pipe G0. An electric stop door v-17, a flow meter, a pneumatic regulating door v-18, a check valve A and a pressure transmitter are arranged on the branch pipe G2 in sequence from the water tank to the secondary air heater. A pneumatic regulating door v-4 is arranged on the branch pipe G2, and a pneumatic regulating door v-5 is arranged on the branch pipe G3.

[0006] Furthermore, the secondary air heater is connected to the water collecting tank through a pipe G4, and an electric stop valve V-19 and a temperature transmitter are provided on the pipe G4.

[0007] Furthermore, the water collecting tank is connected to three parallel branch pipes K1, K2 and K3 through the pipe K0. The branch pipes K1 and K2 are respectively connected to the unit drain trough and the gas turbine expansion. The upper edge of the branch pipe K1 is provided with an inlet electric stop valve v-6, a drain pump A and an outlet electric stop valve v-8 in sequence in the direction away from the water collecting tank. The upper edge of the branch pipe K2 is provided with an inlet electric stop valve v-7, a drain pump B and an outlet electric stop valve v-9 in sequence in the direction away from the water collecting tank. The water collecting tank is connected to the deaerator through the branch pipe K3. The upper edge of the branch pipe K3 is provided with an inlet electric stop valve V-12, a drain pump C, an outlet electric stop valve V-11 and a check valve B in sequence in the direction from the water collecting tank to the deaerator.

[0008] Furthermore, the working fluid of the energy-saving system enters the secondary air heater at the outlet of the blower through the electric stop valve V-17, the flow meter, the pneumatic regulating valve V-18, and the normally closed check valve A to heat the secondary air, and the drain enters the water collecting tank through the electric stop valve V-19. Pressure measuring points and temperature measuring points are added in the middle, and the water level of the water storage tank is controlled by the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5. The pressure of the secondary air heater inlet manifold is controlled by the pneumatic regulating valve V-18.

[0009] Furthermore, the control logic of the pneumatic regulating door V-4 and the pneumatic regulating door V-5 is as follows: when the liquid level in the water tank is 0-1 / 2, the liquid level in the water tank is adjusted only by the pneumatic regulating door V-4, the opening of the pneumatic regulating door V-4 regulating valve is 0-75%, and the adjustment linearity is 1, that is, y=kx+b, y is the regulating valve opening, x is the liquid level in the water tank, k=1, and b is a constant; when the liquid level in the water tank is 1 / 2-1, the liquid level is adjusted jointly by the pneumatic regulating door V-4 and the pneumatic regulating door V-5 regulating valve, the opening of the pneumatic regulating door V-4 regulating valve is 75-100%, and the adjustment linearity is reduced to 1 / 4 of the original linearity, the opening of the pneumatic regulating door V-5 regulating valve is 0-100%, and the adjustment linearity is 1.

[0010] The beneficial effects of the present invention are: The present invention proposes an energy-saving system for improving the secondary air temperature of a direct current boiler during wet operation, which can recover the working fluid and heat discharged to the boiler expansion through a separator after the direct current boiler is converted to a wet state, effectively improving the economy of the unit during deep peak regulation and startup.

[0011] The system and method of the present invention can efficiently recover working fluid and heat, and further can effectively prevent the steam drain pump inlet from vaporizing, thereby increasing its service life.

[0012] The system and method of the present invention can increase the secondary air temperature, thereby improving the boiler efficiency.

[0013] The system and method of the present invention can recycle boiler feed water working fluid and reduce the consumption of desalted water. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the energy-saving system for increasing the secondary air temperature of a once-through boiler in wet operation according to the present invention; Figure 2 It is a schematic diagram of the opening adjustment principle of the pneumatic regulating door V-18 in the energy-saving method of increasing the secondary air temperature during wet operation of a direct current boiler according to the present invention.

[0015] In the figure: 1. water storage tank, 2. self-starting separator on side A, 3. self-starting separator on side B, 4. flow meter, 5. atmospheric expansion tank, 6. water collecting tank, 7. deaerator, 8. unit drainage trough, 9. air machine expansion, 10. secondary air heater, 11. air blower, 12. muffler and inlet filter, 13. check valve A, 14. pressure transmitter, 15. temperature transmitter, 16. drain pump A, 17. drain pump B, 18. drain pump C, 19. check valve B. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The present invention provides an energy-saving system for improving the secondary air temperature of a direct current boiler in wet operation, as shown in FIG1 , comprising a water storage tank 1, wherein both sides of the water storage tank 1 are respectively connected to an A-side self-starting separator 2 and a B-side self-starting separator 3 through pipelines; the water storage tank 1 is respectively connected to an atmospheric expansion tank 5 and a secondary air heater 10 through pipelines, the atmospheric expansion tank 5 is connected to a water collecting tank 6 through pipelines, the water collecting tank 6 is respectively connected to a deaerator 7, a unit drainage trough 8 and an air blower 9 through pipelines, and the secondary air heater 10 is sequentially connected to an air supply fan 11, a silencer and an inlet filter 12.

[0018] The water storage tank 1 is connected to three parallel branch pipes G1, branch pipe G2 and branch pipe G3 through pipe G0. The branch pipe G1 is connected to the secondary air heater 10. The secondary air heater 10 is connected to the air blower 11, the silencer and the inlet filter 12 in sequence. The secondary air heater 10 is connected to the water collecting tank 6 through pipe G4. The pipe G4 is provided with an electric stop valve V-19 and a temperature transmitter 15. The branch pipes G2 and G3 are both connected to the atmospheric expansion tank 5. The main pipe G0 is provided with a pneumatic regulating door v-3. The branch pipe G2 is provided with an electric stop door v-17, a flow meter 4, a pneumatic regulating door v-18, a check valve A13 and a pressure transmitter 14 in sequence along the direction from the water storage tank 1 to the secondary air heater 10. The branch pipe G2 is provided with a pneumatic regulating door v-4, and the branch pipe G3 is provided with a pneumatic regulating door v-5.

[0019] The water collecting tank 6 is connected to three parallel branch pipes K1, K2 and K3 through the pipe K0. The branch pipes K1 and K2 are respectively connected to the unit drainage trough 8 and the gas turbine expansion 9. The inlet electric stop valve v-6, the drain pump A16 and the outlet electric stop valve v-8 are arranged in sequence on the upper edge of the branch pipe K1 away from the water collecting tank 6. The inlet electric stop valve v-7, the drain pump B17 and the outlet electric stop valve v-9 are arranged in sequence on the upper edge of the branch pipe K2 away from the water collecting tank 6. The water collecting tank 6 is connected to the deaerator 7 through the branch pipe K3. The inlet electric stop valve V-12, the drain pump C18, the outlet electric stop valve V-11 and the check valve B19 are arranged in sequence on the upper edge of the branch pipe K3 from the water collecting tank 6 to the deaerator 7.

[0020] The working fluid of the energy-saving system enters the secondary air heater 10 at the outlet of the blower 11 through the electric stop valve V-17, flow meter 4, pneumatic regulating valve V-18, and normally closed check valve A13 to heat the secondary air. The drain enters the water collecting tank 6 through the electric stop valve V-19. Pressure measuring points and temperature measuring points are added in the middle. The water level of the water tank 1 is controlled by the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5. The inlet manifold pressure of the secondary air heater 10 is controlled by the pneumatic regulating valve V-18.

[0021] The control logic of pneumatic regulating door V-4 and pneumatic regulating door V-5 is as follows: when the liquid level of water tank 1 is 0-1 / 2, the liquid level of water tank 1 is adjusted only by pneumatic regulating door V-4, the opening of pneumatic regulating door V-4 regulating valve is 0-75%, and the adjustment linearity is 1, that is, y=kx+b, y is the regulating valve opening, x is the water tank liquid level, k=1, b is a constant; when the liquid level of water tank 1 is 1 / 2-1, the liquid level is adjusted jointly by pneumatic regulating door V-4 and pneumatic regulating door V-5 regulating valve, the opening of pneumatic regulating door V-4 regulating valve is 75-100%, and the adjustment linearity is reduced to 1 / 4 of the original linearity, the opening of pneumatic regulating door V-5 regulating valve is 0-100%, and the adjustment linearity is 1.

[0022] Example 1 The energy-saving system for improving the secondary air temperature of a direct current boiler in wet operation is shown in FIG1 and comprises a water storage tank 1, and both sides of the water storage tank 1 are connected to an A-side self-starting separator 2 and a B-side self-starting separator 3 through pipelines; the water storage tank 1 is connected to an atmospheric expansion tank 5 and a secondary air heater 10 through pipelines, the atmospheric expansion tank 5 is connected to a water collecting tank 6 through pipelines, the water collecting tank 6 is connected to a deaerator 7, a unit drainage trough 8 and an air blower 9 through pipelines, and the secondary air heater 10 is connected to a blower 11, a silencer and an inlet filter 12 in sequence.

[0023] The water storage tank 1 is connected to three parallel branch pipes G1, branch pipe G2 and branch pipe G3 through pipe G0. The branch pipe G1 is connected to the secondary air heater 10. The secondary air heater 10 is connected to the air blower 11, the silencer and the inlet filter 12 in sequence. The secondary air heater 10 is connected to the water collecting tank 6 through pipe G4. The pipe G4 is provided with an electric stop valve V-19 and a temperature transmitter 15. The branch pipes G2 and G3 are both connected to the atmospheric expansion tank 5. The main pipe G0 is provided with a pneumatic regulating door v-3. The branch pipe G2 is provided with an electric stop door v-17, a flow meter 4, a pneumatic regulating door v-18, a check valve A13 and a pressure transmitter 14 in sequence along the direction from the water storage tank 1 to the secondary air heater 10. The branch pipe G2 is provided with a pneumatic regulating door v-4, and the branch pipe G3 is provided with a pneumatic regulating door v-5.

[0024] The water collecting tank 6 is connected to three parallel branch pipes K1, K2 and K3 through the pipe K0. The branch pipes K1 and K2 are respectively connected to the unit drainage trough 8 and the gas turbine expansion 9. The inlet electric stop valve v-6, the drain pump A16 and the outlet electric stop valve v-8 are arranged in sequence on the upper edge of the branch pipe K1 away from the water collecting tank 6. The inlet electric stop valve v-7, the drain pump B17 and the outlet electric stop valve v-9 are arranged in sequence on the upper edge of the branch pipe K2 away from the water collecting tank 6. The water collecting tank 6 is connected to the deaerator 7 through the branch pipe K3. The inlet electric stop valve V-12, the drain pump C18, the outlet electric stop valve V-11 and the check valve B19 are arranged in sequence on the upper edge of the branch pipe K3 from the water collecting tank 6 to the deaerator 7.

[0025] Example 2 The present invention also provides a method for energy saving by increasing the secondary air temperature during wet operation of a direct current boiler, and adopts the system for energy saving by increasing the secondary air temperature during wet operation of a direct current boiler of Example 1, specifically: The working fluid of the energy-saving system enters the secondary air heater 10 at the outlet of the blower 11 through the electric stop valve V-17, flow meter 4, pneumatic regulating valve V-18, and normally closed check valve A13 to heat the secondary air. The drain enters the water collecting tank 6 through the electric stop valve V-19. Pressure measuring points and temperature measuring points are added in the middle. The water level of the water tank 1 is controlled by the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5. The inlet manifold pressure of the secondary air heater 10 is controlled by the pneumatic regulating valve V-18.

[0026] Among them, the control method of the electric regulating valve V-18 is as follows Figure 2 As shown, where: E(s)— Deviation between actual pressure and set pressure; X p — proportionality factor; T (i) s— Integration time;T (D) s— Derivative time; T (f) s- Differential filter time; U(s) —Electric adjustment of the opening of valve V-18.

[0027] Example 3 On the basis of Example 2, the control logic of the pneumatic regulating door V-4 and the pneumatic regulating door V-5 is as follows: when the liquid level of the water tank 1 is 0-1 / 2, the liquid level of the water tank 1 is adjusted only by the pneumatic regulating door V-4, the opening of the pneumatic regulating door V-4 regulating valve is 0-75%, and the adjustment linearity is 1, that is, y=kx+b, y is the regulating valve opening, x is the water tank liquid level, k=1, and b is a constant; when the liquid level of the water tank 1 is 1 / 2-1, the pneumatic regulating door V-4 and the pneumatic regulating door V-5 regulating valves jointly adjust the liquid level, the opening of the pneumatic regulating door V-4 regulating valve is 75-100%, and the adjustment linearity is reduced to 1 / 4 of the original linearity, the opening of the pneumatic regulating door V-5 regulating valve is 0-100%, and the adjustment linearity is 1.

Claims

1. The energy-saving system for increasing the secondary air temperature of a direct-current boiler in wet operation is characterized by: The invention comprises a water storage tank (1), wherein the water storage tank (1) is connected to an atmospheric expansion tank (5) and a secondary air heater (10) through pipelines, the atmospheric expansion tank (5) is connected to a water collecting tank (6) through pipelines, the water collecting tank (6) is connected to a deaerator (7), a unit drainage trough (8) and a gas blower (9) through pipelines, and the secondary air heater (10) is connected to a blower (11), a silencer and an inlet filter (12) in sequence.

2. The energy-saving system for increasing secondary air temperature by wet operation of a once-through boiler according to claim 1 is characterized in that: The two sides of the water storage tank (1) are respectively connected to an A-side self-starting separator (2) and a B-side self-starting separator (3) via pipelines.

3. According to claim 1, the energy-saving system for increasing the secondary air temperature of a once-through boiler in wet operation is characterized in that: The water storage tank (1) is connected to three parallel branch pipes G1, G2 and G3 via a pipe G0. The branch pipe G1 is connected to a secondary air heater (10). The branch pipes G2 and G3 are both connected to an atmospheric expansion tank (5). A pneumatic regulating door v-3 is provided on the main pipe G0. An electric stop door v-17, a flow meter (4), a pneumatic regulating door v-18, a check valve A (13) and a pressure transmitter (14) are provided on the branch pipe G2 in sequence along a direction from the water storage tank (1) to the secondary air heater (10). A pneumatic regulating door v-4 is provided on the branch pipe G2. A pneumatic regulating door v-5 is provided on the branch pipe G3.

4. The energy-saving system for increasing secondary air temperature by wet operation of a once-through boiler according to claim 3 is characterized in that: The secondary air heater (10) is connected to the water collecting tank (6) via a pipeline G4, and an electric stop valve V-19 and a temperature transmitter (15) are provided on the pipeline G4.

5. The energy-saving system for increasing secondary air temperature by wet operation of a once-through boiler according to claim 4 is characterized in that: The water collecting tank (6) is connected to three parallel branch pipes K1, K2 and K3 via a pipe K0. The branch pipes K1 and K2 are respectively connected to the unit drainage trough (8) and the gas turbine expansion (9). An inlet electric stop valve v-6, a drain pump A (16) and an outlet electric stop valve v-8 are sequentially arranged on the upper edge of the branch pipe K1 in a direction away from the water collecting tank (6). An inlet electric stop valve v-7, a drain pump B (17) and an outlet electric stop valve v-9 are sequentially arranged on the upper edge of the branch pipe K2 in a direction away from the water collecting tank (6). The water collecting tank (6) is connected to a deaerator (7) via a branch pipe K3. An inlet electric stop valve V-12, a drain pump C (18), an outlet electric stop valve V-11 and a check valve B (19) are sequentially arranged on the upper edge of the branch pipe K3 in a direction from the water collecting tank (6) to the deaerator (7).

6. The energy-saving system for increasing secondary air temperature by wet operation of a once-through boiler according to claim 5 is characterized in that: The working fluid of the energy-saving system enters the secondary air heater (10) at the outlet of the blower (11) through the electric stop valve V-17, the flow meter (4), the pneumatic regulating valve V-18, and the normally closed check valve A (13) to heat the secondary air. The drain enters the water collecting tank (6) through the electric stop valve V-19. Pressure measuring points and temperature measuring points are added in the middle. The water level of the water storage tank (1) is controlled by the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5. The pressure of the inlet manifold of the secondary air heater (10) is controlled by the pneumatic regulating valve V-18.

7. The energy-saving system for increasing secondary air temperature by wet operation of a once-through boiler according to claim 6 is characterized in that: The control logic of the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5 is as follows: when the liquid level of the water tank (1) is 0-1 / 2, the liquid level of the water tank (1) is adjusted only by the pneumatic regulating valve V-4, the opening of the pneumatic regulating valve V-4 regulating valve is 0-75%, and the adjustment linearity is 1, that is, y=kx+b, y is the regulating valve opening, x is the water tank liquid level, k=1, and b is a constant; when the liquid level of the water tank (1) is 1 / 2-1, the liquid level is adjusted jointly by the pneumatic regulating valve V-4 and the pneumatic regulating valve V-5 regulating valve, the opening of the pneumatic regulating valve V-4 regulating valve is 75-100%, and the adjustment linearity is reduced to 1 / 4 of the original linearity, and the opening of the pneumatic regulating valve V-5 regulating valve is 0-100%, and the adjustment linearity is 1.

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