阅读说明：本技术 循环硫化床机组防干烧及水位调节装置及其控制方法 (Dry burning prevention and water level regulation device for circulating fluidized bed unit and control method thereof ) 是由 郑国蓉 王浩 崔凯平 郑冠捷 赵兴春 王进辉 于 2020-07-20 设计创作，主要内容包括：本发明公开一种循环硫化床机组防干烧及水位调节装置及其控制方法,包括凝汽器、汽封冷却器、冷渣器、低温省煤器、第一低压加热器、第二低压加热器、第三低压加热器和除氧器；凝汽器设置在凝结水管道起始端,除氧器设置在凝结水管道末端。汽封冷却器、冷渣器、低温省煤器、第一低压加热器、第二低压加热器、第三低压加热器和依次设置在凝结水管道上。第一低压加热器后设置有凝结水再循环管道,此管道即为防止冷渣器干烧的系统管道；冷渣器后的回水管道上设置有至凝汽器的管道,此管道即为即为除氧器水位调节系统管道。得到既能调节除氧器水位,又能提供循环流化床冷渣器冷却水的装置,使循环流化床在有凝结水的工况下都可以稳定运行。(The invention discloses a dry combustion preventing and water level adjusting device of a circulating fluidized bed unit and a control method thereof, wherein the dry combustion preventing and water level adjusting device comprises a condenser, a steam seal cooler, a slag cooler, a low-temperature economizer, a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a deaerator; the condenser sets up at the condensate pipe initiating terminal, and the oxygen-eliminating device sets up at the condensate pipe end. The steam seal cooler, the slag cooler, the low-temperature economizer, the first low-pressure heater, the second low-pressure heater and the third low-pressure heater are sequentially arranged on the condensed water pipeline. A condensed water recycling pipeline is arranged behind the first low-pressure heater, and the pipeline is a system pipeline for preventing the slag cooler from being dried; and a pipeline to the condenser is arranged on the water return pipeline behind the slag cooler, and the pipeline is the pipeline of the water level regulating system of the deaerator. The device can adjust the water level of the deaerator and provide cooling water for the slag cooler of the circulating fluidized bed, so that the circulating fluidized bed can stably run under the working condition of condensed water.)

1. Dry combustion method and water level regulating device are prevented to circulation fluidized bed unit, its characterized in that includes: the system comprises a condenser (1), a steam seal cooler (2), a slag cooler (3), a low-temperature economizer (4), a first low-pressure heater (5), a second low-pressure heater (6), a third low-pressure heater (7) and a deaerator (8);

the condenser (1) is arranged at the starting end of the main condensation water pipeline, and the deaerator (8) is arranged at the tail end of the main condensation water pipeline; the steam seal cooler (2), the first low-pressure heater (5), the second low-pressure heater (6) and the third low-pressure heater (7) are sequentially arranged on the main condensed water pipeline according to the flowing direction of the condensed water;

the steam seal cooler (2) is respectively communicated with the slag cooler (3), the low-temperature economizer (4) and the first low-pressure heater (5) along the medium flow direction; a water outlet pipe of the slag cooler (3) is respectively communicated with the first low-pressure heater (5) and the condenser (1); a water outlet pipe of the low-temperature economizer (4) is communicated with a water inlet pipe of a third low-pressure heater (7);

the water outlet pipe of the first low-pressure heater (5) is also communicated with the low-temperature economizer (4) and the water inlet pipe of the condenser (1).

2. The device for preventing dry combustion and adjusting water level of a circulating fluidized bed unit according to claim 1, wherein a main condensation water pipeline from the steam seal cooler (2) to the first low-pressure heater (5) is sequentially provided with a first temperature transmitter (44), a first electric gate valve (9), a low-temperature economizer regulating valve station and a fourth electric gate valve (18) along a medium flow direction; the first electric gate valve (9) is provided with a bypass pipeline, and a first manual gate valve (11), a first pneumatic regulating valve (12) and a second manual gate valve (13) are arranged on the bypass pipeline; the water outlet pipe of the first electric gate valve (9) is also sequentially arranged to the interfaces of the slag cooler (3) and the low-temperature economizer (4); the low-temperature economizer regulating valve station comprises a second electric gate valve (16), a second pneumatic regulating valve (15), a third manual gate valve (17) and a third electric gate valve (14), and the third electric gate valve (14) is arranged on a bypass pipeline of the second electric gate valve (16), the second pneumatic regulating valve (15) and the third manual gate valve (17).

3. The device for preventing dry combustion and adjusting water level of a circulating fluidized bed unit according to claim 1, wherein the main condensation water pipeline from the first low pressure heater (5) to the second low pressure heater (6) is sequentially provided with a second temperature transmitter (45), a fifth electric gate valve (19), a sixth electric gate valve (20) and a third temperature transmitter (46) along the medium flow direction; a recirculation pipeline interface, a low-temperature economizer interface, a slag cooler backwater interface and a second low-pressure heater bypass pipeline interface are arranged between the fifth electric gate valve (19) and the sixth electric gate valve (20) according to the medium flow direction.

4. The device for preventing dry combustion and adjusting water level of a circulating fluidized bed unit according to claim 1, wherein the main condensation water pipelines of the second low pressure heater (6) to the third low pressure heater (7) are sequentially provided with a fourth temperature transmitter (47), a seventh electric gate valve (21), a ninth electric gate valve (23) and a fifth temperature transmitter (48) along the medium flow direction; a second low-pressure heater bypass pipeline interface, a low-temperature economizer return water interface and a third low-pressure heater bypass pipeline interface are arranged between the seventh electric gate valve (21) and the ninth electric gate valve (23) according to the medium flow direction.

5. The device for preventing dry combustion and adjusting water level of circulating fluidized bed unit according to claim 1, wherein the second low pressure heater (6) is provided with a bypass pipe, and an eighth electric gate valve (22) is arranged on the bypass pipe.

6. The device for preventing dry combustion and adjusting water level of a circulating fluidized bed unit according to claim 1, wherein a main condensed water pipeline from the third low-pressure heater (7) to the deaerator (8) is sequentially provided with a sixth temperature transmitter (49), a tenth electric gate valve (24), a first flow measuring device (26), a first pressure transmitter (10) and a first check valve (27) along a medium flow direction; a third low-pressure heater bypass pipeline interface is arranged between the tenth electric gate valve (24) and the first check valve (27) according to the medium flow direction;

the third low-pressure heater (7) is provided with a bypass pipeline, and an eleventh electric gate valve (25) is arranged on the bypass pipeline.

7. The apparatus for preventing dry combustion and adjusting water level of circulating fluidized bed unit according to claim 1, wherein the branch condensed water pipes from the first electric gate valve (9) to the slag cooler (3) are provided with a second flow measuring device (28), a fourth manual gate valve (29) and a twelfth electric gate valve (30) in sequence along the medium flow direction.

8. The dry burning prevention and water level regulation device of the circulating fluidized bed unit as claimed in claim 1, wherein the slag cooler (3) returns water to a condensate pipe in front of the second low-pressure heater (6), and a thirteenth electric gate valve (31), a fifth manual gate valve (32) and a fourteenth electric gate valve (33) are sequentially arranged along a medium flow direction; a port to the condenser (1) is arranged between the fifth manual gate valve (32) and the fourteenth electric gate valve (33) in the medium flowing direction;

and a first electric vacuum gate valve (43) is arranged on a branch condensed water pipeline returning water from the slag cooler (3) to the condenser (1) according to the medium flow direction.

9. The device for preventing dry combustion and adjusting water level of circulating fluidized bed unit according to claim 1, wherein a second pipeline condensed water pipeline to the low-temperature economizer (4) is respectively arranged in front of and behind the first low-pressure heater (5), and a fifteenth electric gate valve (34) is sequentially arranged in the branch condensed water pipeline in front of the first low-pressure heater (5) along the medium flow direction; a sixteenth electric gate valve (35) is sequentially arranged on the branch condensed water pipeline behind the first low-pressure heater (5) along the medium flow direction; two pipelines are converged into a main pipe and enter a low-temperature economizer (4); a seventeenth electric gate valve (36) is arranged on the main pipe along the flowing direction of the medium;

a recirculation pipeline to the condenser (1) is arranged in the condensate pipeline behind the first low-pressure heater (5); a third flow measuring device (38), a sixth manual gate valve (40), a third pneumatic regulating valve (39) and a first manual vacuum gate valve (41) are sequentially arranged along the flowing direction of the condensed water; bypass pipelines are arranged in front of the sixth manual gate valve (40) and behind the first manual vacuum gate valve (41); the bypass pipeline is provided with a second manual vacuum gate valve (42) according to the flowing direction of the condensed water;

and the low-temperature economizer (4) returns water to a condensed water pipeline in front of the third low-pressure heater (7), and the condensed water pipeline is provided with an eighteenth electric gate valve (37) according to the medium flow direction.

10. The method for controlling the dry combustion preventing and water level adjusting device of the circulating fluidized bed unit as set forth in claim 1, comprising the steps of:

the inlet and outlet ends of each low-pressure heater are provided with temperature measuring points, when the difference of the heater ends is different from the thermal equilibrium diagram, the opening of the electric gate valve of the inlet and outlet of the low-pressure heater is controlled, and the water level of the low-pressure heater is adjusted to enable the temperature to reach a set value;

the flow of cooling water of the low-temperature economizer (4) is controlled by a plurality of temperature measuring points, and when the temperature measuring points deviate from a set value, the flow is connected with a thermal control DCS (50) to carry out interlocking control to regulate the amount of condensation water entering the low-temperature economizer;

the cooling water flow of the slag cooler (3) is controlled by a plurality of temperature measuring points, and when the temperature measuring points deviate from a set value, the amount of condensation water entering the low-temperature economizer is adjusted by the linkage control of a thermal control DCS (50);

the water is additionally returned to the condenser by controlling the main condensation water pipeline behind the first low-pressure heater (5), and the gate valve on the main condensation water pipeline and the water level control valve of the deaerator (8) are controlled by the thermal control DCS system (50) to carry out interlocking control so as to control the water level of the deaerator (8).

Technical Field

The invention belongs to the technical field of operation of circulating fluidized bed units, and particularly relates to a dry burning prevention and water level adjustment device for a circulating fluidized bed unit.

Background

In order to accelerate the energy technical innovation, consume inferior coal, protect the environment and save energy, the large and medium-sized thermal power generating units select the circulating fluidized bed units. The circulating fluidized bed has the biggest characteristic that the heat capacity of a boiler is large, once the boiler is stopped or a steam turbine cannot provide cooling water for various reasons, the boiler cannot be cooled, and the boiler is in a dry burning state and is not beneficial to normal operation of the boiler. The slag temperature of the circulating fluidized bed boiler reaches 800-900 ℃ when normal. The hot slag with such a high temperature cannot be cooled by cooling water and normally discharged, so that the heat capacity of the circulating fluidized bed is larger, and systems such as the vulcanizing air and the like cannot normally operate. The boiler will have to be shut down. The ignition time of the circulating fluidized bed boiler is longer than that of a conventional coal-fired unit, and the oil consumption is large. And great inconvenience is brought to the normal operation of the unit. Therefore, the cooling water in the slag cooler is a necessary condition for the safe and stable operation of the circulating fluidized bed unit, namely the cooling water is not allowed to be stopped under various working conditions.

The condensed water of the common circulating fluidized bed unit is recycled behind the shaft seal cooler and is connected out in front of the deaerator water level regulating valve. When the unit is started, condensed water is directly discharged into the condenser through recirculation without entering the low-pressure heater and the deaerator, and further without entering a slag cooler of the circulating fluidized bed. This presents a serious safety hazard to the circulating fluidized bed unit. Therefore, the project recycles the condensed water after the first low-pressure heater, and the condensed water can pass through the slag cooler of the circulating fluidized bed. The pipeline is a device for preventing the circulating fluidized bed from being dried. The minimum flow rate of the cooling water quantity required by the boiler slag cooler under the requirements of the minimum flow rate recirculation condensate pump and the shaft seal cooler and the unit accident condition is larger, so that the shaft seal steam leakage and the door lever steam leakage during the starting and low load of the cooling unit can meet the requirement of the low-load operation of the condensate pump.

In order to save energy and reduce consumption, a low-temperature economizer is also frequently adopted in the circulating fluidized bed unit. The cooling medium of the low-temperature economizer is also condensed water. The condensed water not only needs to provide a water side medium for the low-pressure heater, but also needs to provide cooling water for the slag cooler and the low-temperature economizer. The condensation water is equivalent to a plurality of devices, and the end difference between the devices is more difficult to distribute than that of a pure coal-fired thermal power generating unit. And the resistance to condensate increases. The model selection of the deaerator water level regulating valve is difficult. In order to prevent the dew point corrosion of the flue gas, the water inlet temperature of the condensed water needs to reach the dew point temperature of more than 20 ℃. Therefore, one path of the inlet of the low-temperature economizer comes from the front of the first low-pressure heater, and the other path comes from the back of the first low-pressure heater. The inlet water temperature of the condensed water is maintained at 70 ℃.

When the unit is started at the initial stage, and the condensate pump is started to be recycled, the deaerator is used for supplying water, the main circuit of the third low-pressure heater or the bypass electric valve can be controlled to supply water, and the electric gate valve is poor in linearity and cannot meet the requirement for operation adjustment. And under the abnormal conditions of rapid load reduction, load shedding or deaerator water level fluctuation, the water feeding amount of the deaerator is suddenly reduced, the water feeding adjusting valve of the deaerator is rapidly closed, and the condensed water amount is rapidly reduced. Even if the recirculation regulating valve is fully opened, the minimum flow safety valve of the condensate pump cannot be operated, and the minimum flow required by the slag cooler cannot be ensured.

Disclosure of Invention

The invention aims to overcome the defects of the prior technical scheme and provides an anti-dry heating and water level adjusting device for a circulating fluidized bed unit, which can adjust the water level of a deaerator and provide a device for cooling water of a slag cooler of a circulating fluidized bed, so that the circulating fluidized bed can stably run under the working condition with condensed water and the normal operation of a power plant is not influenced.

In order to achieve the purpose, the invention adopts the following technical scheme:

dry combustion method and water level regulating device are prevented to circulation fluidized bed unit includes: the system comprises a condenser, a steam seal cooler, a slag cooler, a low-temperature economizer, a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a deaerator; the condenser is arranged at the starting end of the main condensation water pipeline, and the deaerator is arranged at the tail end of the main condensation water pipeline; the steam seal cooler, the first low-pressure heater, the second low-pressure heater and the third low-pressure heater are sequentially arranged on the condensed water pipeline according to the flowing direction of the condensed water;

the steam seal cooler is respectively communicated with the slag cooler, the low-temperature economizer and the first low-pressure heater along the medium flow direction; a water outlet pipe of the slag cooler is respectively communicated with the first low-pressure heater and the condenser; a water outlet pipe of the low-temperature economizer is communicated with a water inlet pipe of the third low-pressure heater;

and the water outlet pipe of the first low-pressure heater is also communicated with the water inlet pipes of the low-temperature economizer and the condenser.

As a further improvement of the invention, a main condensation water pipeline from the steam seal cooler to the first low-pressure heater is sequentially provided with a first temperature transmitter, a first electric gate valve, a low-temperature economizer regulating valve station and a fourth electric gate valve along the medium flow direction; the first electric gate valve is provided with a bypass pipeline, and a first manual gate valve, a first pneumatic regulating valve and a second manual gate valve are arranged on the bypass pipeline; the water outlet pipe of the first electric gate valve is also sequentially provided with a connector to the slag cooler and a connector to the low-temperature economizer; the low-temperature economizer regulating valve station comprises a second electric gate valve, a second pneumatic regulating valve, a third manual gate valve and a third electric gate valve, and the third electric gate valve is arranged on bypass pipelines of the second electric gate valve, the second pneumatic regulating valve and the third manual gate valve.

As a further improvement of the invention, a main condensation water pipeline from the first low-pressure heater to the second low-pressure heater is sequentially provided with a second temperature transmitter, a fifth electric gate valve, a sixth electric gate valve and a third temperature transmitter along the medium flow direction; and a recirculation pipeline interface, a low-temperature economizer interface, a slag cooler backwater interface and a second low-pressure heater bypass pipeline interface are arranged between the fifth electric gate valve and the sixth electric gate valve according to the medium flow direction.

As a further improvement of the invention, a fourth temperature transmitter, a seventh electric gate valve, a ninth electric gate valve and a fifth temperature transmitter are sequentially arranged in the main condensation water pipeline from the second low-pressure heater to the third low-pressure heater along the medium flow direction; and a second low-pressure heater bypass pipeline interface, a low-temperature economizer return water interface and a third low-pressure heater bypass pipeline interface are arranged between the seventh electric gate valve and the ninth electric gate valve according to the medium flow direction.

As a further development of the invention, the second low-pressure heater is provided with a bypass line, on which an eighth electric gate valve is arranged.

As a further improvement of the invention, a main condensed water pipeline from the third low-pressure heater to the deaerator is sequentially provided with a sixth temperature transmitter, a tenth electric gate valve, a first flow measuring device, a first pressure transmitter and a first check valve along the medium flow direction; a third low-pressure heater bypass pipeline interface is arranged between the tenth electric gate valve and the first check valve according to the medium flow direction;

the third low-pressure heater is provided with a bypass pipeline, and an eleventh electric gate valve is arranged on the bypass pipeline.

In a further improvement of the present invention, the branch condensed water pipes from the first electric gate valve to the slag cooler are provided with a second flow rate measuring device, a fourth manual gate valve and a twelfth electric gate valve in sequence along the medium flow direction.

As a further improvement of the invention, the slag cooler returns water to a condensate pipe in front of the second low-pressure heater, and a thirteenth electric gate valve, a fifth manual gate valve and a fourteenth electric gate valve are sequentially arranged along the medium flow direction; a port to the condenser is arranged between the fifth manual gate valve and the fourteenth electric gate valve according to the flowing direction of the medium;

and a branch condensed water pipeline from the slag cooler backwater to the condenser is provided with a first electric vacuum gate valve according to the medium flow direction.

As a further improvement of the invention, a branch condensed water pipeline in front of the first low-pressure heater is provided with a fifteenth electric gate valve in sequence along the medium flow direction; a sixteenth electric gate valve is sequentially arranged on the branch condensed water pipeline behind the first low-pressure heater along the medium flow direction; two pipelines are converged into a main pipe and enter a low-temperature economizer; a seventeenth electric gate valve is arranged on the main pipe along the flowing direction of the medium;

the first low-pressure heater rear condensed water pipeline is provided with a recirculation pipeline to the condenser; a third flow measuring device, a sixth manual gate valve, a third pneumatic regulating valve and a first manual vacuum gate valve are sequentially arranged along the flowing direction of the condensed water; bypass pipelines are arranged in front of the sixth manual gate valve and behind the first manual vacuum gate valve; the bypass pipeline is provided with a second manual vacuum gate valve according to the flowing direction of the condensed water;

and the condensate pipeline returns water of the low-temperature economizer to the position in front of the third low-pressure heater, and the condensate pipeline is provided with an eighteenth electric gate valve according to the flow direction of the medium.

The control method of the dry burning prevention and water level adjustment device of the circulating fluidized bed unit comprises the following steps:

the inlet and outlet ends of each low-pressure heater are provided with temperature measuring points, when the difference of the heater ends is different from the thermal equilibrium diagram, the opening of the electric gate valve of the inlet and outlet of the low-pressure heater is controlled, and the water level of the low-pressure heater is adjusted to enable the temperature to reach a set value;

the cooling water flow of the low-temperature economizer is controlled by a plurality of temperature measuring points, and when the temperature measuring points deviate from a set value, the cooling water flow is connected with a thermal control DCS (distributed control system) to carry out linkage control to regulate the amount of condensed water entering the low-temperature economizer;

the cooling water flow of the slag cooler is controlled by a plurality of temperature measuring points, and when the temperature measuring points deviate from a set value, the amount of condensed water entering the low-temperature economizer is adjusted by the linkage control of a thermal control DCS system;

the water return to the condenser is additionally arranged on the main condensation water pipeline behind the first low-pressure heater through control, and the gate valve on the main condensation water pipeline and the deaerator water level control valve are controlled by the thermal control DCS system to perform interlocking control so as to control the deaerator water level.

Compared with the prior art, the invention has the following advantages:

the device is characterized in that a condensed water recycling pipeline is arranged behind a first low-pressure heater, and the system is a system for preventing a slag cooler from being dried; and a pipeline to the condenser is arranged on the water return pipeline behind the slag cooler, and the system is the deaerator water level regulating system. Because set up the pipeline from cold sediment ware return water to condenser all the way, can interlock oxygen-eliminating device water level regulating valve with this assurance condensate pump and cold sediment ware safe operation, also do benefit to and start initial stage operation adjustment. The invention can not only adjust the water level of the deaerator, but also provide a device for cooling water of the slag cooler of the circulating fluidized bed, so that the circulating fluidized bed can stably operate under the working condition of condensed water, and the normal operation of a power plant is not influenced. The method has the advantages of obvious effect, low investment and simple system. Wherein, the dry burning of the circulating fluidized bed is prevented, and the cooling water passes through the slag cooler of the circulating fluidized bed boiler under any working condition. The invention is realized by arranging the condensate recycling pipeline behind the first low-pressure heater, so that even if the engineering is opened under the working condition of minimum flow of the condensate pump, namely recycling, the condensate can also pass through the slag cooler, the condition that cooling water before the slag cooler is cut off does not exist, and the problem is solved from the process path. In the invention, water is additionally returned to the condenser on a pipeline behind the first low-pressure heater, and an electric gate valve is arranged on the pipeline and can be interlocked with DCS (distributed control System) to perform interlocking control with a deaerator water level control valve so as to ensure the deaerator water level.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the present invention in connection with a power plant DCS system.

In the figure, 1-condenser; 2-a gland seal cooler; 3-a slag cooler; 4-low temperature economizer; 5-first low pressure heater (number seven); 6-second Low pressure Heater (number six); 7-third low pressure heater (No. five); 8-a deaerator; 9-a first electric gate valve; 10-a first pressure transmitter; 11-a first manual gate valve; 12-a first pneumatic regulating valve; 13-a second manual gate valve; 14-a third electric gate valve; 15-a second pneumatic regulating valve; 16-a second electric gate valve; 17-a third manual gate valve; 18-a fourth electric gate valve; 19-a fifth electric gate valve; 20-a sixth electric gate valve; 21-seventh electric gate valve; 22-eighth electric gate valve; 23-ninth electric gate valve; 24-tenth electric gate valve; 25-eleventh electric gate valve; 26-a first flow measuring device; 27-a first non-return valve; 28-a second flow measuring device; 29-fourth manual gate valve; 30-twelfth electric gate valve; 31-a thirteenth electric gate valve; 32-a fifth manual gate valve; 33-a fourteenth electrically operated gate valve; 34-a fifteenth electrically operated gate valve; 35-sixteenth electric gate valve; 36-a seventeenth electric gate valve; 37-eighteenth electric gate valve; 38-third flow measuring means; 39-third pneumatic regulating valve; 40-a sixth manual gate valve; 41-a first manual vacuum gate valve; 42-second manual vacuum gate valve; 43-a first electric vacuum gate valve; 44-a first temperature transmitter; 45-a second temperature transmitter; 46-third temperature transmitter; 47-fourth temperature transmitter; 48-a fifth temperature transmitter; 49-sixth temperature transmitter; 50-thermal control DCS system.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

The following detailed description of the present application will be made in conjunction with the accompanying drawings and detailed description of the present application.

As shown in fig. 1, the dry combustion preventing and water level adjusting device of the circulating fluidized bed unit comprises a condenser 1, a steam seal cooler 2, a slag cooler 3, a low-temperature economizer 4, a first low-pressure heater 5, a second low-pressure heater 6, a third low-pressure heater 7 and a deaerator 8; condenser 1 sets up at the condensate pipe initiating terminal, and oxygen-eliminating device 8 sets up at the condensate pipe end.

The steam seal cooler 2, the first low-pressure heater 5, the second low-pressure heater 6 and the third low-pressure heater 7 are sequentially arranged on the condensed water pipeline according to the flowing direction of the condensed water;

the steam seal cooler 2 is respectively communicated with the slag cooler 3, the low-temperature economizer 4 and the first low-pressure heater 5 along the medium flow direction; a water outlet pipe of the slag cooler 3 is respectively communicated with the first low-pressure heater 5 and the condenser 1; a water outlet pipe of the low-temperature economizer 4 is communicated with a water inlet pipe of a third low-pressure heater 7;

the water outlet pipe of the first low-pressure heater 5 is also communicated with the low-temperature economizer 4 and the water inlet pipe of the condenser 1.

A condenser: a heat exchanger for condensing turbine exhaust steam into water. The condenser is mainly used in a steam turbine power device and is divided into a water-cooling condenser and an air-cooling condenser. The condenser can condense the exhaust steam of the turbine into water for reuse by the boiler, and can establish vacuum and maintain the vacuum at the exhaust steam part of the turbine.

A steam seal cooler: the steam-gas mixture is used for pumping the steam-gas mixture of the steam turbine steam seal system, and the steam is prevented from leaking into a steam engine room and an oil system from the end steam seal to pollute the environment and damage the oil quality. The steam-gas mixture enters the shaft seal cooler to be cooled into water, the condensed water is heated, and the residual gas which is not condensed is discharged to the atmosphere.

A slag cooler: reduce the ash cooling device with high slag discharging temperature of the circulating fluidized bed unit.

First low pressure heater, second low pressure heater, third low pressure heater: the low-pressure heater has the functions of utilizing the steam which does partial work in the steam turbine to be pumped into the heater to heat the condensed water, improving the temperature of the condensed water, reducing the amount of the steam discharged into the condenser by the steam turbine, reducing the energy loss and improving the circulation efficiency of a thermodynamic system.

A deaerator: heating to saturation temperature corresponding to the operating pressure of the deaerator, removing oxygen and other gases dissolved in the feed water, preventing and reducing corrosion of boiler feed water pipes, economizers and other ancillary equipment.

A low-temperature economizer: the boiler is heated to saturated water heated surface under the pressure of steam drum, and because it absorbs the heat of high-temp. flue gas, it reduces the temp. of flue gas discharged from boiler, saves energy source and raises efficiency, so that it is called coal-saving device.

A condensed water recycling pipeline is arranged behind the first low-pressure heater 5, and the pipeline is a system pipeline for preventing the slag cooler from being dried; and a pipeline to the condenser 1 is arranged on a water return pipeline behind the slag cooler 3, and the pipeline is a pipeline of the water level regulating system of the deaerator 8.

The condensate pipeline from the steam seal cooler 2 to the first low-pressure heater 5 is sequentially provided with a first temperature transmitter 44 and a first electric gate valve 9 along the medium flow direction. The first electric gate valve 9 is provided with a bypass pipeline, and a first manual gate valve 11, a first pneumatic regulating valve 12 and a second manual gate valve 13 are arranged on the bypass pipeline; the first electric gate valve 9 is provided with a low-temperature economizer regulating valve station behind, and consists of a second electric gate valve 16, a second pneumatic regulating valve 15, a third manual gate valve 17 and a third electric gate valve 14. In the medium flowing direction, a fourth electric gate valve 18 is arranged in front of the inlet of the first low-pressure heater 5. The first temperature transmitter 44, the first pneumatic control valve 12, the second pneumatic control valve 15, the first electric gate valve 9, the second electric gate valve 16, the third electric gate valve 14 and the fourth electric gate valve 18 are connected with the DCS system of the thermal power plant, and when the inlet temperature of the low-temperature economizer fails to meet the design requirements, the remote control can be realized through the regulating valve station of the low-temperature economizer.

The condensate pipes of the first low pressure heater 5 to the second low pressure heater 6 are sequentially provided with a second temperature transmitter 45, a fifth electric gate valve 19, a sixth electric gate valve 20 and a third temperature transmitter 46 along the medium flow direction. And the second temperature transmitter 45, the fifth electric gate valve 19, the sixth electric gate valve 20 and the third temperature transmitter 46 are connected with a DCS (distributed control System) system of a thermal power plant, so that the temperature of the outlet of the first low-pressure heater and the temperature of the inlet of the second low-pressure heater can meet the design requirements.

The condensate pipes of the second to third low-pressure heaters 6 to 7 are provided with a fourth temperature transmitter 47, a seventh electric gate valve 21, a ninth electric gate valve 23 and a fifth temperature transmitter 48 in this order along the medium flow direction. And the fourth temperature transmitter 47, the seventh electric gate valve 21, the ninth electric gate valve 23 and the fifth temperature transmitter 48 are connected with a DCS (distributed control System) system of the thermal power plant, so that the temperature of the outlet of the second low-pressure heater and the temperature of the inlet of the third low-pressure heater can meet the design requirements.

The second low-pressure heater 6 is provided with a bypass conduit on which an eighth electric gate valve 22 is arranged. The eighth electric gate valve 22 is connected to the DCS system of the thermal power plant. And the sixth electric gate valve 20 and the seventh electric gate valve 21 are closed through remote control, and the eighth electric gate valve 22 is opened simultaneously to realize the bypass function of the second low-pressure heater.

The condensate pipes from the third low-pressure heater 7 to the deaerator 8 are sequentially provided with a sixth temperature transmitter 49, a tenth electric gate valve 24, a first flow measuring device 26, a first pressure transmitter 10 and a first check valve 27 along the medium flow direction. The sixth temperature transmitter 49, the tenth electric gate valve 24, the first flow measuring device 26, and the first pressure transmitter 50 are connected to the thermal power plant DCS system. And the outlet temperature and pressure of the third low-pressure heater meet the design requirements.

The third low pressure heater 7 is provided with a bypass conduit on which an eleventh electric gate valve 25 is arranged. The eleventh electric gate valve 25 is connected to the DCS system of the thermal power plant. And the ninth electric gate valve 23 and the tenth electric gate valve 24 are closed through remote control, and the eleventh electric gate valve 25 is opened at the same time, so that the third low-pressure heater bypass function is realized.

Behind the first electric gate valve 9 is arranged a condensate line to the slag cooler 3, in which a second flow measuring device 28, a fourth manual gate valve 29 and a twelfth electric gate valve 30 are arranged in this order in the medium flow direction. The second flow measuring device 28 and the twelfth electric gate valve 30 are connected to the DCS system of the thermal power plant, thereby realizing remote control.

The slag cooler 3 returns water to a condensate pipeline in front of the second low-pressure heater 6, and a thirteenth electric gate valve 31, a fifth manual gate valve 32 and a fourteenth electric gate valve 33 are sequentially arranged along the medium flow direction. And the thirteenth electric gate valve 31 and the fourteenth electric gate valve 33 are connected with a DCS (distributed control system) of the thermal power plant to realize remote control.

The slag cooler 3 returns water to a condensed water pipeline of the condenser 1, and the condensed water pipeline is the water level adjusting device of the deaerator 8. A first electric vacuum gate valve 43 is provided in accordance with the flow direction of the medium, and the first electric vacuum gate valve 43 is connected to the DCS system of the thermal power plant. When the unit starts the dynamic initial stage, when condensate pump recirculation starts 8 water supplies of back oxygen-eliminating device of accomplishing, under the load, get rid of load or 8 undulant abnormal conditions of oxygen-eliminating device water level fast moreover, through the cold first electronic vacuum gate valve 43 of control, guarantee to congeal pump and cold sediment ware safe operation, also do benefit to and start initial stage operation adjustment to realize remote control.

A pipeline condensed water pipeline from the front part to the back part of the low-temperature economizer 4 is arranged at the front part and the back part of the first low-pressure heater 5 respectively, and a fifteenth electric gate valve 34 is sequentially arranged in the condensed water pipeline in front of the first low-pressure heater 5 along the medium flow direction; a sixteenth electric gate valve 35 is sequentially arranged on the condensed water pipeline behind the first low-pressure heater 5 along the medium flow direction; the two pipelines are converged into a main pipe and enter the low-temperature economizer 4. This main pipe is provided with a seventeenth electric gate valve 36 along the direction of medium flow. And the fifteenth electric gate valve 34, the sixteenth electric gate valve 35 and the seventeenth electric gate valve 36 are connected with a DCS (distributed control System) of the thermal power plant and interlocked with the second pneumatic regulating valve to control the inlet temperature of the low-temperature economizer.

The low-temperature economizer 4 returns water to a condensed water pipeline in front of the third low-pressure heater 7. The condensate pipe is provided with an eighteenth electric gate valve 37 according to the medium flow direction. Eighteenth electric gate valve 37 is connected with the thermal power plant DCS system to realize remote control.

The first low pressure heater 5 rear condensate conduit is provided with a recirculation conduit to the condenser 1. A third flow rate measuring device 38, a sixth manual gate valve 40, a third pneumatic control valve 39, and a first manual vacuum gate valve 41 are provided in this order in the direction in which the condensate flows. The bypass line is provided with a second hand-operated vacuum gate valve 42 in the direction of the flow of the condensate. The pipeline is a device for preventing the slag cooler from being dried by the circulating fluidized bed unit. The third flow measuring device 38 and the third pneumatic control valve 39 are connected to the DCS system of the thermal power plant. When the third pneumatic regulating valve 39 is opened, condensed water flows through the slag cooler, and remote control is realized.

According to the invention, the recirculation valve is opened under any working condition through the recirculation regulating valve 39, so that condensed water at the upstream flows through the slag cooler, and the phenomenon that the circulating fluidized bed unit cannot be cooled to influence the normal operation of the unit is prevented; and the first electric vacuum gate valve 43 and the fourteenth electric gate valve 33 are controlled in an interlocking manner, so that the water level regulation of the deaerator 8 under the severe working conditions of low load, load shedding and the like can be further ensured.

As shown in FIG. 2, valves, temperature transmitters and pressure transmitters on all pipelines of the invention are all connected to a DCS system of a power plant, so that remote online synchronous monitoring is realized, and automatic control and adjustment can be carried out.

The working process of the invention is as follows:

temperature measuring points are arranged at the front and the rear of each low-pressure heater, and when the end difference of the heaters is different from the thermal balance diagram, the opening of the electric gate valve at the inlet and the outlet of the heaters can be controlled, and the water level of the low-pressure heaters is adjusted to enable the temperature to reach a set value.

The cooling water flow of the low-temperature economizer is controlled through a first temperature measuring point (the position of the temperature measuring point corresponding to the temperature transmitter), a second temperature measuring point and a fifth temperature measuring point. When the fifth temperature measuring point deviates from the set value, the second pneumatic regulating valve, the seventeenth electric gate valve and the fourteenth electric gate valve can be controlled by the DCS in a linkage mode, and the amount of condensed water entering the low-temperature economizer is regulated.

The cooling water flow of the slag cooler is controlled by a first temperature measuring point, a second temperature measuring point and a third temperature measuring point. When the third temperature measuring point deviates from the set value, the twelfth electric gate valve and the thirteenth electric gate valve can be controlled in a linkage manner through the DCS, and the amount of condensed water entering the low-temperature economizer is adjusted.

The deaerator water level change can be interlocked through a first pneumatic regulating valve and a first electric vacuum valve and controlled through DCS.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the applicant consider that such subject matter is not considered part of the disclosed subject matter.