Supercritical coal-fired unit 20% load dry-state operation water supply control system

Abstract

The invention discloses a supercritical coal-fired unit 20% load dry-state operation water supply control system, which belongs to the technical field of supercritical coal-fired unit dry-state operation, is connected to a water supply pipeline, and comprises a pipe body, a supporting structure, a water outlet pipe and a regulation and control structure, the two ends of the pipe body are connected with connecting pieces used for being connected with a water supply pipeline main pipeline. The water outlet pipe is arranged in the pipe body and fixed to the inner wall of the pipe body through a supporting structure. The regulation and control structure comprises a regulation unit and a control unit; a plurality of water outlets are uniformly formed in the outer wall of the water outlet pipe, and the other end of the water outlet pipe is opened towards the adjusting unit; the adjusting unit is arranged in the pipe body, connected with the water outlet pipe and used for adjusting the water outlet amount; the adjusting unit is fixedly connected to the inner wall of the pipe body through a supporting structure; the control unit is arranged outside the pipe body, penetrates through the pipe body to be connected with the adjusting unit and is used for controlling the adjusting unit to adjust the water outlet pipe. The device has the advantages that the water supply amount can be regulated and controlled through the change of the enthalpy value, and accurate control can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of dry operation of supercritical coal-fired units, and more specifically relates to a 20% load dry operation water supply control system for supercritical coal-fired units. Background Art

[0002] When a supercritical coal-fired unit is running in dry state, changes in turbine valve position, fuel quantity, and feedwater flow rate will cause changes in the steam-water interface inside the boiler. Therefore, the coal-water ratio is an important parameter that reflects the working medium balance during boiler operation. The feedwater control of a supercritical coal-fired unit is the key to the safe operation of the entire unit. The feedwater flow rate must ensure that the fluctuation of the steam-water separation interface is small at any time, so as to ensure that the main steam temperature control and water-cooled wall temperature control of the boiler fluctuate little and are within the design range. Therefore, it is necessary to strictly control the amount of fuel and feedwater.

[0003] The correctness of the coal-to-water ratio of a direct current boiler can be directly reflected from the steam parameters. The key point of optimizing and adjusting the water supply control system is to find a suitable variable and measuring point that can accurately and stably reflect the steam parameters. The correction logic for the coal-to-water ratio control currently usually takes the enthalpy of slightly superheated steam as a sign of whether the coal-to-water ratio is appropriate. Since the enthalpy of superheated steam cannot be measured directly, it needs to be obtained through a series of calculations on the temperature and pressure of the steam, and the calculated enthalpy of superheated steam changes dramatically, which increases the instability of the control system. Therefore, how to provide a water supply control device that can use the change in the enthalpy of superheated steam to adjust the water supply and accurately supply water is a problem that technicians in this field urgently need to solve. Summary of the invention

[0004] In view of this, the present invention provides a 20% load dry-state water supply control system for a supercritical coal-fired unit, which adopts the following technical solutions:

[0005] A 20% load dry-state operation water supply control system for a supercritical coal-fired unit is connected to a water supply pipeline, and comprises a pipe body, a supporting structure, a water outlet pipe and a regulating structure; both ends of the pipe body are connected with connectors for connecting to a main pipe of the water supply pipeline; the water outlet pipe is arranged inside the pipe body and fixed to the inner wall of the pipe body through the supporting structure; the regulating structure comprises a regulating unit and a control unit; one end of the water outlet pipe is closed, a plurality of water outlets are evenly arranged on the outer wall, and the other end is open toward the regulating unit; the regulating unit is arranged inside the pipe body, connected to the water outlet pipe, and used to adjust the water outlet size; the regulating unit is fixedly connected to the inner wall of the pipe body through the supporting structure; the control unit is arranged outside the pipe body, penetrates the pipe body and is connected to the regulating unit, and is used to control the regulating unit to regulate the water outlet pipe.

[0006] Furthermore, the connecting piece is a connecting nut, one end of which is fixedly connected to the pipe body and has a thread arranged inside, and the other end of which is threadedly connected to the main pipe of the water supply pipeline through the thread.

[0007] Furthermore, the supporting structure includes a first fixing ring arranged at a closed end of the water outlet pipe and a second fixing ring arranged at an open end of the water outlet pipe; the first fixing ring and the second fixing ring are fixed to the outside of the water outlet pipe to fix the water outlet pipe to the inside of the pipe body; the first fixing ring is provided with a plurality of through holes along the circumference for passing water; the second fixing ring is used to close the channel between the water outlet pipe and the pipe body.

[0008] Furthermore, the adjusting unit includes a hollow piston, a piston rod and a driving mechanism; the outer diameter of the hollow piston is adapted to the inner diameter of the water outlet pipe; one end of the hollow piston extends into the water outlet pipe from the opening of the water outlet pipe; the hollow piston extends into the opening of one end of the water outlet pipe, and the other end is evenly provided with a plurality of fixing rods along the circumference, and a certain angle is formed between each fixing rod to form a gap; one end of the fixing rod is fixedly connected to the inner wall of the hollow piston, and the other end is fixedly connected to the piston rod; the other end of the piston rod is connected to the driving mechanism.

[0009] Furthermore, the support structure includes a plurality of third fixing rings arranged outside the driving mechanism for fixing the driving mechanism inside the tube body; the third fixing rings are provided with a plurality of through holes along the circumferential direction for passing water.

[0010] Furthermore, the driving mechanism includes a power cylinder; a pneumatic chamber, a hydraulic chamber and a movable chamber are sequentially arranged inside the power cylinder; a movable plate is arranged between the pneumatic chamber and the hydraulic chamber to separate the pneumatic chamber and the hydraulic chamber; the inner diameters of the pneumatic chamber and the hydraulic chamber are the same; the pneumatic chamber is connected to the control unit through a gas pipeline to the outside; the hydraulic chamber is connected to the control unit through a liquid pipeline to the outside; the hydraulic chamber is connected to the movable chamber, and the inner diameter of the movable chamber is larger than the inner diameter of the hydraulic chamber; the end opening of the power cylinder located on one side of the movable chamber is used to connect the end of the piston rod away from the hollow piston.

[0011] Furthermore, the control unit includes a controller, a hydraulic control mechanism and a pneumatic control mechanism; the controller is connected to the hydraulic control mechanism and the pneumatic control mechanism for remote control; the pneumatic control mechanism is connected to the gas pipeline, and the hydraulic control mechanism is connected to the liquid pipeline.

[0012] Furthermore, the hydraulic control mechanism includes a hydraulic motor, a liquid pump and a liquid tank. The hydraulic motor is connected to the liquid pump to push the liquid tank to push the liquid into or suck it out of the hydraulic cavity, and the inflow and outflow of the liquid in the hydraulic cavity is controlled through a liquid pipeline.

[0013] Furthermore, the air pressure control mechanism includes a first air pump, a heat exchange pipe, a signal amplifying chamber, a pneumatic motor, a second air pump and an air box; one end of the first air pump is connected to the steam drum, and the other end is connected to the heat exchange pipe; the other end of the heat exchange pipe is connected to the water supply pipeline; the heat exchange pipe is arranged in the upper cavity of the signal amplifying chamber, and the upper cavity of the signal amplifying chamber is provided with a gas whose volume changes due to temperature; an expansion plate is provided inside the signal amplifying chamber to separate the upper cavity and the lower cavity, which has a heat insulating effect; a distance measuring sensor is provided on one side of the lower cavity of the signal amplifying chamber for monitoring the position of the expansion plate; the distance measuring sensor and the pneumatic motor are both connected to the controller; the pneumatic motor is connected to the second air pump, and the second air pump is connected to the air box, which is used to pump the gas in the air box into or out of the pneumatic cavity.

[0014] The beneficial effects of the present invention are:

[0015] The present invention provides a water supply control system for a supercritical coal-fired unit in dry operation at 20% load. The control system converts the change of gas enthalpy value of a steam drum into mechanical energy and transmits it to the hydraulic pressure in a hydraulic cavity in a pipe body, thereby controlling the movement of a piston rod and a hollow piston to increase or decrease the number of water outlets, thereby making the control of water supply more precise, and enabling its control process to be connected to the change of gas enthalpy value of the steam drum, thereby making the control of water supply more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the internal structure of the tube body of the present invention.

[0018] Figure 2 It is a structural schematic diagram of the air pressure control mechanism of the present invention.

[0019] Among them, in the figure:

[0020] 1-tube body; 2-water outlet pipe; 3-connecting piece; 4-hollow piston; 5-piston rod; 6-fixing rod; 7-first fixing ring; 8-second fixing ring; 9-third fixing ring; 10-air pressure chamber; 11-hydraulic chamber; 12-moving chamber; 13-controller; 14-first air pump; 15-heat exchange pipe; 16-signal amplification chamber; 17-pneumatic motor; 18-second air pump; 19-air box; 20-expansion plate; 21-distance sensor. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please see attached Figure 1-2 The present invention provides a 20% load dry-state operation water supply control system for a supercritical coal-fired unit, which is connected to a water supply pipeline and comprises a pipe body 1, a supporting structure, a water outlet pipe 2 and a regulating structure; both ends of the pipe body 1 are connected with connectors 3 for connecting to a main pipe of the water supply pipeline; the connector 3 is a connecting nut, one end of which is fixedly connected to the pipe body 1 and is provided with a thread inside, and the other end is threadedly connected to the main pipe of the water supply pipeline through a thread, so that the pipe body 1 is connected to the main pipe of the water supply pipeline; the water outlet pipe 2 is arranged inside the pipe body 1 and fixed to the inner wall of the pipe body 1 through a supporting structure; the regulating structure comprises a regulating unit and a control unit; the regulating unit is arranged inside the pipe body 1 and connected to the water outlet pipe 2 for adjusting the water outlet size; the regulating unit is fixedly connected to the inner wall of the pipe body 1 through the supporting structure; the control unit is arranged outside the pipe body 1, penetrates the pipe body 1 and is connected to the regulating unit, and is used to control the regulating unit to regulate the water outlet pipe 2.

[0023] One end of the water outlet pipe 2 is closed, and a plurality of water outlets are evenly arranged on the outer wall, and the other end is open toward the adjusting unit; the adjusting unit includes a hollow piston 4, a piston rod 5 and a driving mechanism; the outer diameter of the hollow piston 4 is adapted to the inner diameter of the water outlet pipe 2, and one end of the hollow piston 4 extends into the water outlet pipe 2 from the open end of the water outlet pipe 2; the hollow piston 4 extends into the open end of the water outlet pipe 2, and the other end is evenly arranged with a plurality of fixing rods 6 along the circumferential direction, and each fixing rod 6 has a certain angle to form a gap with a certain area; one end of the fixing rod 6 is fixedly connected to the inner wall of the hollow piston 4, and the other end is fixedly connected to the piston rod 5; the other end of the piston rod 5 is connected to the driving mechanism.

[0024] The support structure includes a first fixing ring 7 disposed at a closed end of the water outlet pipe 2 and a second fixing ring 8 disposed at an open end of the water outlet pipe 2; the first fixing ring 7 and the second fixing ring 8 are fixedly disposed outside the water outlet pipe 2 to fix the water outlet pipe 2 inside the pipe body 1; the first fixing ring 7 is provided with a plurality of through holes along the circumference for passing water; the second fixing ring 8 is used to close the passage between the water outlet pipe 2 and the pipe body 1. The support structure also includes a plurality of third fixing rings 9 disposed outside the driving mechanism to fix the driving mechanism inside the pipe body 1. The third fixing ring 9 is provided with a plurality of through holes along the circumference for passing water.

[0025] The driving mechanism includes a power cylinder; a pneumatic chamber 10, a hydraulic chamber 11 and a movable chamber 12 are sequentially arranged inside the power cylinder; a movable plate is arranged between the pneumatic chamber 10 and the hydraulic chamber 11, which is used to separate the pneumatic chamber 10 and the hydraulic chamber 11; the inner diameters of the pneumatic chamber 10 and the hydraulic chamber 11 are the same; the pneumatic chamber 10 is connected to the control unit through a gas pipeline; the hydraulic chamber 11 is connected to the control unit through a liquid pipeline; the hydraulic chamber 11 is connected to the movable chamber 12, and the inner diameter of the movable chamber 12 is larger than the inner diameter of the hydraulic chamber 11; the end opening of the power cylinder located on one side of the movable chamber 12 is used to connect the end of the piston rod 5 away from the hollow piston 4.

[0026] The control unit includes a controller 13, a hydraulic control mechanism and a pneumatic control mechanism.

[0027] The hydraulic control mechanism includes a hydraulic motor, a liquid pump and a liquid tank, which are not shown in the figure. The hydraulic motor is connected to the liquid pump to push the liquid tank to push or suck the liquid into or out of the hydraulic chamber 11, and the liquid in and out of the hydraulic chamber 11 is controlled through the liquid pipeline, thereby pushing the piston rod 5 and the hollow piston 4 to move in the moving chamber 12 and the water outlet pipe 2 respectively. The side wall of the hollow piston 4 shields the water outlet of the water outlet pipe 2 during the movement, thereby controlling the water output of the water outlet pipe 2. The controller 13 is connected to the hydraulic control mechanism and the air pressure control mechanism for remote control.

[0028] The air pressure control mechanism is connected to the gas pipeline, and by adjusting the air pressure in the air pressure chamber 10, the position of the movable plate is pushed, thereby adjusting the hydraulic pressure in the hydraulic chamber 11. The air pressure control mechanism includes a first air pump 14, a heat exchange pipe 15, a signal amplifying chamber 16, a pneumatic motor 17, a second air pump 18 and an air box 19; one end of the first air pump 14 is connected to the steam drum, and the other end is connected to the heat exchange pipe 15, and the gas in the steam drum is pumped into the heat exchange pipe 15; the heat exchange pipe 15 is arranged in the upper cavity of the signal amplifying chamber 16, and the upper cavity of the signal amplifying chamber 16 is provided with a gas whose volume changes greatly due to temperature; an expansion sheet 20 is arranged inside the signal amplifying chamber 16, which separates the upper cavity and the lower cavity and has a heat insulation effect; a distance sensor 21 is arranged on one side of the lower cavity of the signal amplifying chamber 16, which is used to monitor the position of the expansion sheet 20. The temperature change of the heat exchange pipe 15 causes the gas in the upper cavity to push the expansion sheet 20 to move, thereby amplifying the change in the enthalpy value of the gas in the heat exchange pipe 15 and converting the enthalpy value change into mechanical energy. The distance sensor 21 and the pneumatic motor 17 are both connected to the controller 13. The distance sensor 21 transmits a signal to the controller 13, and the controller 13 controls the opening and closing of the pneumatic motor 17. The pneumatic motor 17 is connected to the second air pump 18, and the second air pump 18 is connected to the air box 19 to pump the gas in the air box 19 into or out of the pneumatic cavity 10. The other end of the heat exchange pipe 15 is connected to the water supply pipeline. After the heat exchange in the upper cavity of the signal amplification cavity 16, the temperature of the heat exchange pipe 15 decreases and becomes liquid, and the liquid is transported to the water supply pipeline again.

[0029] The air pressure control mechanism transmits the signal of the change of the gas enthalpy value in the steam drum to the controller 13, and converts the signal to control the liquid in the air pressure chamber 10, pushes the position of the movable plate, and thus adjusts the hydraulic pressure in the hydraulic chamber 11; the piston rod 5 and the hollow piston 4 are moved by hydraulic control, so that the side wall of the hollow piston 4 covers or releases the water outlet on the side wall of the water outlet pipe 2, and the water output is accurately controlled by increasing or decreasing the number of water outlets.

[0030] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0031] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A water supply control system for 20% load dry operation of a supercritical coal-fired unit, characterized in that: The device is connected to a water supply pipeline and comprises a pipe body (1), a supporting structure, a water outlet pipe (2) and a regulating structure; both ends of the pipe body (1) are connected with connecting pieces (3) for connecting to the main pipe of the water supply pipeline; the water outlet pipe (2) is arranged inside the pipe body (1) and is fixed to the inner wall of the pipe body (1) through the supporting structure; the regulating structure comprises a regulating unit and a control unit; one end of the water outlet pipe (2) is closed, a plurality of water outlets are evenly arranged on the outer wall, and the other end is open toward the regulating unit; the regulating unit is arranged inside the pipe body (1) and connected to the water outlet pipe (2) for regulating the water outlet size; the regulating unit is fixedly connected to the inner wall of the pipe body (1) through the supporting structure; the control unit is arranged outside the pipe body (1), passes through the pipe body (1) and is connected to the regulating unit, and is used to control the regulating unit to regulate the water outlet pipe (2).

2. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 1 is characterized in that: The connecting piece (3) is a connecting nut, one end of which is fixedly connected to the pipe body (1), a thread is provided inside, and the other end is threadedly connected to the main pipe of the water supply pipeline through the thread.

3. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 1, characterized in that: The support structure comprises a first fixing ring (7) arranged at a closed end of the water outlet pipe (2) and a second fixing ring (8) arranged at an open end of the water outlet pipe (2); the first fixing ring (7) and the second fixing ring (8) are fixedly arranged outside the water outlet pipe (2) to fix the water outlet pipe (2) inside the pipe body (1); the first fixing ring (7) is provided with a plurality of through holes along the circumference for passing water; the second fixing ring (8) is used to close the passage between the water outlet pipe (2) and the pipe body (1).

4. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 1, characterized in that: The regulating unit comprises a hollow piston (4), a piston rod (5) and a driving mechanism; the outer diameter of the hollow piston (4) is matched to the inner diameter of the water outlet pipe (2); one end of the hollow piston (4) extends into the water outlet pipe (2) from the opening of the water outlet pipe (2); the hollow piston (4) extends into the opening of the water outlet pipe (2), and the other end is evenly provided with a plurality of fixing rods (6) along the circumference, and each fixing rod (6) has a certain angle to form a gap; one end of the fixing rod (6) is fixedly connected to the inner wall of the hollow piston (4), and the other end is fixedly connected to the piston rod (5); the other end of the piston rod (5) is connected to the driving mechanism.

5. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 4, characterized in that: The support structure comprises a plurality of third fixing rings (9) arranged outside the driving mechanism, and used to fix the driving mechanism inside the tube body (1); the third fixing ring (9) is provided with a plurality of through holes along the circumference for passing water.

6. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 4, characterized in that: The driving mechanism comprises a power cylinder; a pneumatic chamber (10), a hydraulic chamber (11) and a movable chamber (12) are sequentially arranged inside the power cylinder; a movable plate is arranged between the pneumatic chamber (10) and the hydraulic chamber (11) for separating the pneumatic chamber (10) and the hydraulic chamber (11); the inner diameters of the pneumatic chamber (10) and the hydraulic chamber (11) are the same; the pneumatic chamber (10) is connected to the control unit through a gas pipeline; the hydraulic chamber (11) is connected to the control unit through a liquid pipeline; the hydraulic chamber (11) is connected to the movable chamber (12), and the inner diameter of the movable chamber (12) is larger than the inner diameter of the hydraulic chamber (11); the end opening of the power cylinder located on one side of the movable chamber (12) is used to connect the end of the piston rod (5) away from the hollow piston (4).

7. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 6, characterized in that: The control unit comprises a controller (13), a hydraulic control mechanism and a pneumatic control mechanism; the controller (13) is connected to the hydraulic control mechanism and the pneumatic control mechanism for remote control; the pneumatic control mechanism is connected to the gas pipeline, and the hydraulic control mechanism is connected to the liquid pipeline.

8. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 7, characterized in that: The hydraulic control mechanism comprises a hydraulic motor, a liquid pump and a liquid tank. The hydraulic motor is connected to the liquid pump to push the liquid tank to push the liquid into or suck it out of the hydraulic chamber (11), and the inflow and outflow of the liquid in the hydraulic chamber (11) is controlled through a liquid pipeline.

9. The supercritical coal-fired unit 20% load dry state operation water supply control system according to claim 7, characterized in that: The air pressure control mechanism comprises a first air pump (14), a heat exchange pipe (15), a signal amplifying chamber (16), a pneumatic motor (17), a second air pump (18) and an air box (19); one end of the first air pump (14) is connected to a steam drum, and the other end is connected to the heat exchange pipe (15); the other end of the heat exchange pipe (15) is connected to a water supply pipeline; the heat exchange pipe (15) is arranged in the upper cavity of the signal amplifying chamber (16), and a gas whose volume changes under the influence of temperature is arranged in the upper cavity of the signal amplifying chamber (16); the signal amplifying chamber (16) is provided with a gas whose volume changes under the influence of temperature; the signal amplifying chamber (16) is provided with a second air pump (18) and a second air box (19); the first air pump (14) is connected to a steam drum at one end, and the heat exchange pipe (15) is connected to a water supply pipeline at the other end; the heat exchange pipe (15) is connected to a water supply pipeline at the other end; the heat exchange pipe (15) is arranged in the upper cavity of the signal amplifying chamber (16), and the gas whose volume changes under the influence of temperature is arranged in the upper cavity of the signal amplifying chamber (16); the signal amplifying chamber (16) is provided with a second air pump (18) and a second air box (19); the first air pump (14) is connected to a steam drum at one end, and the heat exchange pipe (15) is connected to a water supply pipeline at the other end; the heat exchange pipe (15) is connected to a water supply pipeline at the other end; the heat exchange pipe (15) is connected to a water supply pipeline at one ... 16) is provided with an expansion sheet (20) inside to separate the upper cavity and the lower cavity and have a heat insulation effect; a distance sensor (21) is provided on one side of the lower cavity of the signal amplifying cavity (16) for monitoring the position of the expansion sheet (20); the distance sensor (21) and the pneumatic motor (17) are both connected to the controller (13); the pneumatic motor (17) is connected to the second air pump (18), and the second air pump (18) is connected to the air box (19) for pumping the gas in the air box (19) into or sucking out the gas in the air box (19) into the pneumatic cavity (10).

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