CN112856374B - Heat re-extraction steam heating control system and method for coupling pressure matcher - Google Patents

Abstract

The invention discloses a heat re-extraction steam heating control system and method coupled with a pressure matcher. The pressure matcher is controlled by coupling a multi-nozzle needle valve, and the opening of the regulating needle valve is used to realize the regulation of the outlet flow and pressure of the pressure matcher. The double closed-loop control system composed of two controllers working in series is selected, and the sub-controller is used to control the disturbance of desuperheating water in advance, so as to reduce the influence of the disturbance of desuperheating water on the outlet steam temperature. The temperature setting feedforward can weaken the disturbance effect caused by the change of the driving steam and the suction steam parameters caused by the change of the working condition of the unit, and the control is more accurate. The invention solves the difficult and precise control problems such as the large lag and time constant of the steam temperature at the outlet of the pressure matcher, the strong and frequent interference effect of the desuperheating water, and the change of driving/inhaling steam parameters due to working condition changes.

Description

A heat re-extraction steam heating control system and method coupled with a pressure matcher

technical field

The invention relates to the field of automatic control of steam extraction and heating systems for thermal power units, in particular to a thermal re-extraction steam heating control system and method coupled with a pressure matcher.

Background technique

With the rapid development of my country's economy and industry, the amount of industrial steam and residential steam has also increased. Cogeneration of coal-fired units is still one of the important ways to meet the current steam load. At the same time, with the deepening and improvement of my country's power system reform and energy conservation and emission reduction policies, power generation enterprises must ensure safe production in the competition of market opening and online bidding, and at the same time have more urgent requirements for unit operation economy. Therefore, how to effectively It is the research focus of current heating technology to reduce the heat consumption of cogeneration heat supply and realize the thermal electrolysis coupling.

At present, the steam in the hot section of the reheater, the cold section of the reheater, and the exhaust steam of the medium pressure cylinder can all be selected as heating steam. According to the requirements of different users' steam parameters, a reasonable steam heating method can be selected to realize the cascade utilization of steam. Taking the industrial steam with higher parameters as the research object, the hot and cold re-extraction steam is mostly used for heat supply. After analysis, due to the high extraction steam temperature in the hot section, under the premise of satisfying the same heat supply, the extraction steam quantity If the amount of condensed steam increases (under the same condition of steam intake), the power generation of the unit increases. Of course, the enthalpy value of the extraction steam in the hot section consumes a lot of boiler heat, but considering the operation mode of the boiler, when the evaporation rate is constant, the boiler coal consumption remains unchanged. Therefore, reducing the amount of superheated steam will only increase the exhaust gas temperature compared to extracting steam in the cold section. Therefore, it is more appropriate to use the hot section extraction steam than the cold section extraction steam from the analysis of thermal economy alone. At the same time, the amount of extraction steam in the cold section is limited by the over-temperature of the reheater. Generally, the data given by the boiler factory is about 5% of the boiler evaporation. Due to the limited steam extraction in the cold section, the hot section extraction is generally used when the required steam supply is large and the temperature is high.

At present, the conventional steam supply methods and control methods mainly include the following:

1. Steam supply by steam turbine extraction and pressure regulation, such as rotating diaphragm, regulating butterfly valve, seat cylinder valve, etc., all use valve throttling to adjust steam pressure, or directly reduce temperature and pressure through high-pressure steam to meet the needs of heat users. parameter. This heating method has a great throttling effect, resulting in throttling loss of non-heating steam, especially when the proportion of heat supply in the total flow is small, the throttling loss is greater, which sacrifices steam It wastes a lot of high-pressure steam working power.

2. Heat supply through a single-nozzle pressure matcher, use high-pressure steam to suck low-pressure steam, and achieve the required steam parameters after mixing. Due to the change of load, the steam parameters change accordingly, and the same pressure matcher structure will cause the suction ratio. Different, making the controllable effect not good. Although the heat utilization efficiency is high, it is greatly affected by the change of unit load and steam parameters, the adjustable range is narrow, and the flow rate cannot be adjusted, so it is not suitable for the operation of the unit under variable working conditions. At present, the adjustable multi-nozzle pressure matcher is a new type of pressure matcher developed on the basis of a single nozzle. There are multiple injectors inside, and each injector has an independent braking device, which can uniformly control the pressure and pressure of the matcher. The flow rate can be adjusted within a larger range of steam flow, thus providing a favorable means for the thermo-electrolysis coupling control of thermal power plants. However, at present, the outlet temperature and pressure of the pressure matcher are controlled through the traditional PID to control the opening of the needle valve and the reduction of the desuperheater. The amount of warm water has a general control effect, and has a large inertia and delay.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the above-mentioned prior art, the present invention proposes a heat re-extraction steam heating control system and method coupled with a pressure matcher. The present invention uses a multi-nozzle needle valve to control the outlet pressure and flow of the pressure matcher, which can The steam flow can be automatically controlled in a wide range, and the contradiction that the flow of the pressure matcher cannot be adjusted is solved; the cascade control method is used to control the steam temperature at the outlet of the pressure matcher, which is composed of two controllers working in series. The double closed-loop control system uses the sub-controller to control the disturbance of desuperheating water in advance to reduce the influence of the disturbance on the outlet steam temperature, and solve the problem that the lag and time constant of the outlet steam temperature of the pressure matcher are large, and the disturbance of desuperheating water is strong, frequent and difficult. Control precise puzzles.

In order to achieve the above object, the present invention adopts the following technical solutions:

A heat re-extraction steam heating control system coupled with a pressure matcher, the outlet of the heat exchanger in the boiler 1 is connected with the inlet of the high-pressure cylinder 2 of the steam turbine, the outlet of the high-pressure cylinder 2 is connected with the inlet of the reheater in the boiler 1, and the reheater in the boiler 1 is connected. The outlet of the heater is respectively connected with the middle regulating door 5 and the hot re-extraction check valve 6, the middle regulating door 5 is connected with the middle pressure cylinder 3, and then is connected with the low pressure cylinder 4; The valve 7 is connected, the desuperheating water check valve 8 is connected with the desuperheating water regulating valve 9, and then the hot re-extraction steam regulating valve 7 and the desuperheating water regulating valve 9 are connected with the desuperheater 10, and then the desuperheater 10 is sequentially connected with the driving steam temperature sensor. 11. The driving steam pressure sensor 12 is connected with the driving steam flow sensor 13, the medium pressure cylinder 3 is connected with the suction steam regulating valve 14, and then the suction steam regulating valve 14 is sequentially connected with the suction steam flow sensor 15, the suction steam pressure sensor 16 and the suction steam temperature. The sensor 17 is connected to the suction steam check valve 18, and the driving steam flow sensor 13 and the suction steam check valve 18 are connected to the adjustable multi-nozzle pressure matcher 19, and then the adjustable multi-nozzle pressure matcher 19 is sequentially connected with the steam supply. The main pipe steam flow sensor 20, the steam supply main pipe steam pressure sensor 21 and the steam supply main pipe steam temperature sensor 22 are connected; Then the pressure matcher needle valve controller 24 is connected with the adjustable multi-nozzle pressure matcher 19; the steam pressure sensor 21 of the steam supply main pipe and the set value 25 of the steam outlet temperature of the unit are connected with the theoretical enthalpy value of the heating main pipe The calculation module 26 is connected, the suction steam pressure sensor 16 and the suction steam temperature sensor 17 are connected with the suction steam enthalpy value calculation module 27, the driving steam flow sensor 13 and the suction steam flow sensor 15 are connected with the current operating condition extraction coefficient calculation module 28, and then The theoretical enthalpy value calculation module 26 of the heat supply main management, the suction steam enthalpy value calculation module 27 and the current operating condition extraction coefficient calculation module 28 are connected to the driving steam theoretical enthalpy value calculation module 29, the driving steam pressure sensor 12 and the driving steam theoretical enthalpy value The calculation module 29 is connected with the driving steam theoretical temperature calculation module 30, the driving steam temperature sensor 11 and the driving steam theoretical temperature calculation module 30 are connected with the desuperheating water regulating valve advance controller 31, the set value of the steam supply outlet temperature of the unit is 25 and the steam supply mother. The pipe steam temperature sensor 22 is connected to the main controller 32 of the desuperheating water regulating valve, and the driving steam temperature sensor 11 and the main controller 32 of the desuperheating water regulating valve are connected to the sub-controller 33 of the desuperheating water regulating valve, and then the desuperheating water regulating valve leads the controller 31 The sub-controller 33 of the desuperheating water regulating valve is connected with the desuperheating water regulating valve 9 .

The adjustable multi-nozzle pressure matching device 19 is provided with a plurality of injectors, and each injector has an independent braking device, which can control the pressure and flow uniformly and adjust it within a larger range of steam flow.

The pressure matcher needle valve controller 24 , the desuperheating water regulating valve advance controller 31 , the desuperheating water regulating valve main controller 32 and the desuperheating water regulating valve sub-controller 33 all use PID controllers.

The described control method of a heat re-extraction steam heating control system coupled with a pressure matcher is as follows: the boiler 1 transfers heat to the boiler feed water through its internal heat exchanger, so that the boiler feed water becomes high-temperature and high-pressure steam, and then drives the boiler 1. The high-pressure cylinder 2 performs power generation, the exhaust steam from the high-pressure cylinder 2 enters the reheater in the boiler 1 for heat exchange, and then the high-temperature steam passes through the middle-adjustment door 5 to drive the middle-pressure cylinder 3 and the low-pressure cylinder 4 to generate power; in front of the middle-adjustment door 5 Part of the high-temperature steam is drawn out from the reheater of the boiler 1, and sent to the desuperheater 10 through the hot re-extraction check valve 6 and the hot re-extraction regulating valve 7, and the desuperheating water sprayed by the desuperheating water regulating valve 9 is adjusted to enter the desuperheater. The driving steam temperature of the adjustable multi-nozzle pressure matcher 19 drives the low-temperature extraction steam of the medium pressure cylinder 3, and enters the adjustable multi-nozzle pressure matcher 19 through the suction steam regulating valve 14 and the suction steam check valve 18 for mixing to the required level. steam parameters for heating users;

The actual steam supply main pipe steam flow measured by the steam supply main pipe steam flow sensor 20 and the actual demand heat supply flow 23 on the user side are sent to the pressure matcher needle valve controller 24 for calculation to generate needle valve control instructions, thereby controlling the adjustable multi- The opening of the nozzle pressure matcher 19 meets the outlet flow and pressure requirements; the steam pressure of the main pipe measured by the steam pressure sensor 21 of the steam supply main pipe and the set value 25 of the outlet temperature of the steam supply of the unit are sent to the heating main pipe for calculation of the theoretical enthalpy value The module 26 calculates and obtains the theoretical enthalpy value of the heating master; the suction steam pressure measured by the suction steam pressure sensor 16 and the suction steam temperature measured by the suction steam temperature sensor 17 are sent to the suction steam enthalpy value calculation module 27 to calculate and obtain the suction steam enthalpy value; The steam flow measured by the driving steam flow sensor 13 and the suction steam flow sensor 15 is sent to the injection coefficient calculation module 28 of the current working condition to calculate the extraction coefficient, and then the theoretical enthalpy value calculation module 26 of the heat supply mother, the suction steam enthalpy value The results calculated by the calculation module 27 and the current operating condition extraction coefficient calculation module 28 are sent to the driving steam theoretical enthalpy value calculation module 29 for energy balance calculation to obtain the driving steam theoretical enthalpy value, and then the calculated driving steam theoretical enthalpy value and driving steam pressure are calculated. The driving steam pressure measured by the sensor 12 is sent to the driving steam theoretical temperature calculation module 30 for calculation to obtain the driving steam theoretical temperature, and then the driving steam temperature measured by the driving steam temperature sensor 11 and the driving theoretical temperature are simultaneously sent to the desuperheating water regulating valve advance controller 31 to obtain Command 1 for desuperheating water control valve; on the other hand, the steam temperature of the steam supply main pipe measured by the steam supply outlet temperature set value 25 of the unit and the steam temperature sensor 22 of the steam supply main pipe is sent to the main controller 32 of the desuperheating water control valve, and then The calculation result and the driving steam temperature measured by the driving steam temperature sensor 11 are sent to the sub-controller 33 of the desuperheating water regulating valve for calculation to obtain the second command of the desuperheating water regulating valve; The superimposed action controls the opening of the desuperheating water regulating valve 9 and realizes the precise control of the outlet temperature of the steam supply of the pressure matcher.

Below the disadvantages of the prior art and the advantages of the technical solution of the present invention are discussed as follows:

(1) At present, most of the heating units use temperature-reducing and pressure-reducing valves for heating control, and most of the control methods use the heating outlet pressure as the adjustment purpose, which cannot achieve precise control of the flow. Due to the long heating pipeline and large inertia, the change of heating pressure has a large hysteresis, so it is relatively extensive to control the heating flow to meet the needs of heat users; Flow effect, waste a lot of high-temperature steam energy.

(2) Heating is provided by a single-nozzle pressure matcher, and high-pressure steam is used to suck low-pressure steam. After mixing, the required steam parameters are achieved, avoiding the throttling loss of high-temperature steam. However, due to the change of the unit load, the extraction parameters will change accordingly. The same pressure matcher structure will cause different extraction ratios, making the controllable effect poor. Although the heat utilization efficiency is high, it is greatly affected by the change of unit load and steam parameters, the adjustable range is narrow, and the flow rate cannot be adjusted, so it is not suitable for the operation of the unit under variable working conditions.

(3) The control system and method of the present invention is controlled based on an adjustable multi-nozzle pressure matcher, which is provided with a plurality of injectors, and each injector has an independent braking device, which can uniformly control the pressure and pressure of the matcher. The flow rate can be adjusted within a larger range of steam flow, thus providing a favorable means for the thermo-electrolysis coupling adjustment control of thermal power plants. Directly control the outlet temperature and pressure of the pressure matcher, the control effect is general, and it has large inertia and delay.

(4) In the present invention, the opening of the regulating needle valve is used to realize the regulation of the outlet flow and pressure of the pressure matcher, and at the same time, a cascade control system is selected to adjust the steam temperature of the pressure matcher. The variables form a sub-controller loop to complete the coarse adjustment control of the outlet steam temperature, and at the same time use the main controller loop to complete the fine adjustment of the outlet steam temperature. , to weaken the disturbance effect of desuperheating water on the outlet steam temperature; in addition, under the variable load condition of the unit, the parameters of driving steam and suction steam change in real time. There will be a certain lag. The present invention can obtain the temperature feedforward of the driving steam ahead of time, which can weaken the disturbance effect caused by the change of the parameters of the driving steam and the suction steam caused by the change of the working condition of the unit, and the control is more accurate.

Description of drawings

FIG. 1 is a schematic diagram of the connection of a heat re-extraction steam heating control system coupled with a pressure matcher according to the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a heat re-extraction steam heating control system of the present invention coupled with a pressure matching device, the outlet of the heat exchanger in the boiler 1 is connected to the inlet of the high-pressure cylinder 2 of the steam turbine, and the outlet of the high-pressure cylinder 2 is reheated in the boiler 1 The outlet of the reheater in the boiler 1 is connected to the middle regulating door 5 and the hot re-extraction check valve 6 respectively. The middle regulating door 5 is connected to the middle pressure cylinder 3 and then to the low pressure cylinder 4; The valve 6 is connected with the hot re-extraction regulating valve 7, the desuperheating water check valve 8 is connected with the desuperheating water regulating valve 9, and then the hot re-extraction regulating valve 7 and the desuperheating water regulating valve 9 are connected with the desuperheater 10, and then the temperature is reduced. The device 10 is sequentially connected with the driving steam temperature sensor 11, the driving steam pressure sensor 12 and the driving steam flow sensor 13, the medium pressure cylinder 3 is connected with the suction steam regulating valve 14, and then the suction steam regulating valve 14 is sequentially connected with the suction steam flow sensor 15, the suction steam The steam pressure sensor 16 is connected with the suction steam temperature sensor 17, and then connected with the suction steam check valve 18, the driving steam flow sensor 13 and the suction steam check valve 18 are connected with the adjustable multi-nozzle pressure matcher 19, and then the adjustable multi-nozzle The pressure matcher 19 is sequentially connected with the steam supply main pipe steam flow sensor 20, the steam supply main pipe steam pressure sensor 21 and the steam supply main pipe steam temperature sensor 22; the actual demand heat supply flow 23 on the user side and the steam supply main pipe steam flow sensor 20 is connected to the pressure matcher needle valve controller 24, and then the pressure matcher needle valve controller 24 is connected to the adjustable multi-nozzle pressure matcher 19; the steam supply main pipe steam pressure sensor 21 and the unit steam supply outlet temperature set value 25 It is connected with the theoretical enthalpy value calculation module 26 of the heating master, the suction steam pressure sensor 16 and the suction steam temperature sensor 17 are connected with the suction steam enthalpy value calculation module 27, and the driving steam flow sensor 13 and the suction steam flow sensor 15 are connected to the current working condition. The injection coefficient calculation module 28 is connected, and then the heat supply main management theoretical enthalpy calculation module 26, the suction steam enthalpy calculation module 27 and the current operating condition injection coefficient calculation module 28 are connected with the driving steam theoretical enthalpy calculation module 29, and the driving steam pressure The sensor 12 and the driving steam theoretical enthalpy value calculation module 29 are connected with the driving steam theoretical temperature calculation module 30, the driving steam temperature sensor 11 and the driving steam theoretical temperature calculation module 30 are connected with the desuperheating water regulating valve advance controller 31, and the steam supply outlet temperature of the unit is connected. The set value 25 and the steam temperature sensor 22 of the steam supply main pipe are connected to the main controller 32 of the desuperheating water regulating valve, and the driving steam temperature sensor 11 and the main controller 32 of the desuperheating water regulating valve are connected to the sub-controller 33 of the desuperheating water regulating valve. The desuperheating water regulating valve advance controller 31 and the desuperheating water regulating valve sub-controller 33 are connected to the desuperheating water regulating valve 9 .

As a preferred embodiment of the present invention, the adjustable multi-nozzle pressure matcher 19 is provided with a plurality of injectors, and each injector has an independent braking device, which can uniformly control the pressure and flow in a large steam flow range Internal regulation.

As a preferred embodiment of the present invention, the pressure matcher needle valve controller 24, the desuperheating water regulating valve advance controller 31, the desuperheating water regulating valve main controller 32 and the desuperheating water regulating valve sub-controller 33 all use PID controllers . The basic principle of PID controller is as follows:

Among them, P(t) is the output control command of the controller; K is the set parameter gain; e(t) is the deviation between the actual input value of the controller and the theoretical setting value of the controller module at time t; T _i represents the integration time, and T _d represents the derivative time.

As a preferred embodiment of the present invention, the current operating condition extraction coefficient calculation module 28 can obtain the extraction coefficient of the pressure matcher by calculating the actual steam flow measured by the driving steam flow sensor 13 and the suction steam flow sensor 15 . Calculated as follows:

μ _{= GH} /GP

Among them: _GH is the suction steam flow; _GP is the driving steam flow.

As a preferred embodiment of the present invention, the theoretical enthalpy value calculation module 26 of the heat supply mother, the suction steam enthalpy value calculation module 27, the driving steam theoretical enthalpy value calculation module 29 and the driving steam theoretical temperature calculation module 30 use water and steam The thermodynamic properties calculation formula is solved to obtain the steam enthalpy value and temperature value. Calculated as follows:

Among them: p, T, h are pressure, temperature, enthalpy respectively, p ^* , T ^* , h ^* are fixed values, n _i , I _i , J _i , n _i1 , J _i1 , n _i2 , I _i2 , J _i2 is a set of constants, and R is the gas constant.

As shown in FIG. 1, the control method of a heat re-extraction steam heating control system coupled with a pressure matcher according to the present invention is as follows: the boiler 1 transfers heat to the boiler feed water through its internal heat exchanger, so that the boiler feed water changes It is high-temperature and high-pressure steam, and then drives the high-pressure cylinder 2 to generate power. The exhaust steam from the high-pressure cylinder 2 enters the reheater in the boiler 1 for heat exchange, and then the high-temperature steam drives the intermediate-pressure cylinder 3 and the low-pressure cylinder 4 through the middle regulating door 5 for production. Power generation; part of the high-temperature steam is drawn out in front of the middle regulating door 5 and after the reheater of the boiler 1, and sent to the desuperheater 10 through the hot re-extraction check valve 6 and the hot re-extraction regulating valve 7, and passes through the desuperheating water regulating valve 9 The sprayed desuperheating water adjusts the temperature of the driving steam entering the adjustable multi-nozzle pressure matcher 19, thereby driving the low-temperature extraction steam of the medium pressure cylinder 3, and enters the adjustable multi-nozzle pressure through the suction steam regulating valve 14 and the suction steam check valve 18 The matcher 19 mixes to the required steam parameters for heating users;

The actual steam supply main pipe steam flow measured by the steam supply main pipe steam flow sensor 20 and the actual demand heat supply flow 23 on the user side are sent to the pressure matcher needle valve controller 24 for calculation to generate needle valve control instructions, thereby controlling the adjustable multi- The opening of the nozzle pressure matcher 19 meets the outlet flow and pressure requirements; the steam pressure of the main pipe measured by the steam pressure sensor 21 of the steam supply main pipe and the set value 25 of the outlet temperature of the steam supply of the unit are sent to the heating main pipe for calculation of the theoretical enthalpy value The module 26 calculates and obtains the theoretical enthalpy value of the heating master; the suction steam pressure measured by the suction steam pressure sensor 16 and the suction steam temperature measured by the suction steam temperature sensor 17 are sent to the suction steam enthalpy value calculation module 27 to calculate and obtain the suction steam enthalpy value; The steam flow measured by the driving steam flow sensor 13 and the suction steam flow sensor 15 is sent to the injection coefficient calculation module 28 of the current working condition to calculate the extraction coefficient, and then the theoretical enthalpy value calculation module 26 of the heat supply mother, the suction steam enthalpy value The results calculated by the calculation module 27 and the current operating condition extraction coefficient calculation module 28 are sent to the driving steam theoretical enthalpy value calculation module 29 for energy balance calculation to obtain the driving steam theoretical enthalpy value, and then the calculated driving steam theoretical enthalpy value and driving steam pressure are calculated. The driving steam pressure measured by the sensor 12 is sent to the driving steam theoretical temperature calculation module 30 for calculation to obtain the driving steam theoretical temperature, and then the driving steam temperature measured by the driving steam temperature sensor 11 and the driving theoretical temperature are simultaneously sent to the desuperheating water regulating valve advance controller 31 to obtain Command 1 for desuperheating water control valve; on the other hand, the steam temperature of the steam supply main pipe measured by the steam supply outlet temperature set value 25 of the unit and the steam temperature sensor 22 of the steam supply main pipe is sent to the main controller 32 of the desuperheating water control valve, and then The calculation result and the driving steam temperature measured by the driving steam temperature sensor 11 are sent to the sub-controller 33 of the desuperheating water regulating valve for calculation to obtain the second command of the desuperheating water regulating valve; The superimposed action controls the opening of the desuperheating water regulating valve 9 and realizes the precise control of the outlet temperature of the steam supply of the pressure matcher.

Claims (4)

1. The utility model provides a hot steam extraction heating control system again of coupling pressure matcher which characterized in that: the system comprises a boiler (1), wherein an outlet of a heat exchanger in the boiler (1) is connected with an inlet of a high-pressure cylinder (2) of a steam turbine, an outlet of the high-pressure cylinder (2) is connected with an inlet of an inner reheater in the boiler (1), an outlet of the inner reheater in the boiler (1) is respectively connected with a middle adjusting door (5) and a hot re-extraction check valve (6), the middle adjusting door (5) is connected with a middle pressure cylinder (3), and then is connected with a low pressure cylinder (4); the hot re-extraction check valve (6) is connected with the hot re-extraction regulating valve (7), the desuperheating water check valve (8) is connected with the desuperheating water regulating valve (9), then the hot re-extraction regulating valve (7) and the desuperheating water regulating valve (9) are connected with the desuperheater (10), then the desuperheater (10) is sequentially connected with the driving steam temperature sensor (11), the driving steam pressure sensor (12) and the driving steam flow sensor (13), the intermediate pressure cylinder (3) is connected with the suction steam regulating valve (14), then the suction steam regulating valve (14) is sequentially connected with the suction steam flow sensor (15), the suction steam pressure sensor (16) and the suction steam temperature sensor (17) and then is connected with the suction steam check valve (18), the driving steam flow sensor (13) and the suction steam check valve (18) are connected with the adjustable multi-nozzle pressure matcher (19), then the adjustable multi-nozzle pressure matcher (19) is sequentially connected with a steam flow sensor (20) of a steam supply main pipe, a steam pressure sensor (21) of the steam supply main pipe and a steam temperature sensor (22) of the steam supply main pipe; a user side actual demand heat supply flow (23) and a steam supply main pipe steam flow sensor (20) are connected with a pressure matcher needle valve controller (24), and then the pressure matcher needle valve controller (24) is connected with an adjustable multi-nozzle pressure matcher (19); a steam pressure sensor (21) of a steam supply main pipe and a set value (25) of a steam supply outlet temperature of a unit are connected with a theoretical enthalpy value calculation module (26) of the steam supply main pipe, an inhalation steam pressure sensor (16) and an inhalation steam temperature sensor (17) are connected with an inhalation steam enthalpy value calculation module (27), a driving steam flow sensor (13), an inhalation steam flow sensor (15) and a current working condition injection coefficient calculation module (28) are connected, then the theoretical enthalpy value calculation module (26) of the steam supply main pipe, the inhalation steam enthalpy value calculation module (27) and the current working condition injection coefficient calculation module (28) are connected with a driving steam theoretical enthalpy value calculation module (29), the driving steam pressure sensor (12) and the driving steam theoretical enthalpy value calculation module (29) are connected with a driving steam theoretical temperature calculation module (30), the driving steam temperature sensor (11) and the driving steam theoretical temperature calculation module (30) are connected with a temperature-reducing valve advance water controller (31 and advance water controller (31) ) And the set steam supply outlet temperature set value (25) and the steam supply main pipe steam temperature sensor (22) are connected with the desuperheating water regulating valve main controller (32), the drive steam temperature sensor (11) and the desuperheating water regulating valve main controller (32) are connected with the desuperheating water regulating valve auxiliary controller (33), and then the desuperheating water regulating valve advanced controller (31) and the desuperheating water regulating valve auxiliary controller (33) are connected with the desuperheating water regulating valve (9).

2. The system for controlling heat re-extraction and heat supply coupled with the pressure matcher as claimed in claim 1, wherein: a plurality of ejectors are arranged in the adjustable multi-nozzle pressure matcher (19), each ejector is provided with an independent braking device, and pressure and flow can be uniformly controlled to be adjusted within a large steam flow range.

3. The heat re-extraction and heat supply control system coupled with the pressure matcher as claimed in claim 1, wherein: and the pressure matcher needle valve controller (24), the desuperheating water regulating valve lead controller (31), the desuperheating water regulating valve main controller (32) and the desuperheating water regulating valve auxiliary controller (33) adopt PID controllers.

4. The method for controlling a heat re-extraction and heat supply control system coupled with a pressure matcher as claimed in any one of claims 1 to 3, wherein: the boiler (1) transfers heat to boiler feed water through an internal heat exchanger thereof, so that the boiler feed water is changed into high-temperature high-pressure steam, then a high-pressure cylinder (2) is driven to do work and generate electricity, the exhaust steam of the high-pressure cylinder (2) enters a reheater in the boiler (1) to exchange heat, and then the high-temperature steam drives a middle-pressure cylinder (3) and a low-pressure cylinder (4) through a middle adjusting door (5) to do work and generate electricity; leading out partial high-temperature steam in front of the middle adjusting door (5) and behind a reheater of the boiler (1), sending the partial high-temperature steam into the desuperheater (10) through a hot re-steam extraction check valve (6) and a hot re-steam extraction regulating valve (7), regulating the driving steam temperature entering the adjustable multi-nozzle pressure matcher (19) through desuperheating water sprayed by the desuperheating water regulating valve (9), so as to drive the low-temperature steam extraction of the middle pressure cylinder (3), and entering the adjustable multi-nozzle pressure matcher (19) through a suction steam regulating valve (14) and a suction steam check valve (18) to be mixed to required steam parameters for heat supply users to use;

sending the actual steam flow of the steam supply main pipe and the actual heat supply flow (23) required by a user side, which are measured by the steam flow sensor (20) of the steam supply main pipe, into a needle valve controller (24) of the pressure matcher to calculate and generate a needle valve control instruction, so that the opening degree of the adjustable multi-nozzle pressure matcher (19) is controlled to meet the requirements of outlet flow and pressure; the steam pressure of a main pipe measured by a steam pressure sensor (21) of a steam supply main pipe and a set value (25) of the temperature of a steam supply outlet of a unit are sent to a theoretical enthalpy value calculation module (26) of the heat supply main pipe to calculate and obtain the theoretical enthalpy value of the heat supply main pipe; sending the suction steam pressure measured by the suction steam pressure sensor (16) and the suction steam temperature measured by the suction steam temperature sensor (17) into a suction steam enthalpy value calculation module (27) for calculation to obtain a suction steam enthalpy value; the steam flow measured by the driving steam flow sensor (13) and the suction steam flow sensor (15) is sent to a current working condition injection coefficient calculation module (28) for calculation to obtain an injection coefficient, then, the results calculated by a heat supply main pipe theoretical enthalpy value calculation module (26), an intake steam enthalpy value calculation module (27) and a current working condition injection coefficient calculation module (28) are sent to a driving steam theoretical enthalpy value calculation module (29) for energy balance calculation to obtain a driving steam theoretical enthalpy value, then the calculated driving steam theoretical enthalpy value and driving steam pressure measured by a driving steam pressure sensor (12) are sent to a driving steam theoretical temperature calculation module (30) for calculation to obtain a driving steam theoretical temperature, and then the steam temperature measured by a driving steam temperature sensor (11) and the driving theoretical temperature are simultaneously sent to a desuperheating water regulating valve advanced controller (31) to obtain a desuperheating water regulating valve instruction I; on the other hand, the steam temperature of the steam supply main pipe measured by the set steam supply outlet temperature set value (25) and the steam temperature sensor (22) of the steam supply main pipe is sent to the main controller (32) of the temperature-reducing water regulating valve, and then the calculation result and the driving steam temperature measured by the driving steam temperature sensor (11) are sent to the auxiliary controller (33) of the temperature-reducing water regulating valve together to be calculated to obtain a second instruction of the temperature-reducing water regulating valve; and the first order of the temperature-reducing water regulating valve and the second order of the temperature-reducing water regulating valve are superposed to control the opening degree of the temperature-reducing water regulating valve (9), so that the accurate control of the temperature of the steam supply outlet of the pressure matcher is realized.

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