CN206018578U - A add medicine and sampling system for combined cycle generating set multi-pressure exhaust-heat boiler - Google Patents

Abstract

The utility model discloses a dosing and sampling system suitable for a multi-pressure waste heat boiler of a combined cycle generator set. The dosing system is: condensed water and feed water are treated with automatic ammonia addition, and the dosing point is the outlet of the condensed water pump (or the outlet of refined desalination) and before the desalinated water replenishment valve; the water of the multi-pressure drum boiler is added with phosphate or sodium hydroxide Treatment, for the system where the low-pressure steam drum boiler water is medium and high-pressure feed water, only add medicine to the medium and high-pressure steam drum; when the system has a fine desalination device, an automatic feed water oxygenation system is added, and the oxygen addition point is the inlet of the medium-pressure feed water pump , High-pressure water pump inlet. This dosing system can achieve the beneficial effects of reducing the corrosion of condensate and water supply systems, reducing the amount of boiler scaling, and effectively improving the safety, reliability and economic performance of the unit. The sampling system is newly added low-pressure economizer or condensate water heater outlet, medium-pressure economizer outlet, and high-pressure economizer outlet sampling points to effectively monitor the corrosion of the low-temperature heating surface.

Description

A Dosing and Sampling System for Multi-pressure Waste Heat Boilers of Combined Cycle Generating Units

Technical field:

The utility model belongs to the technical field of waste heat boilers of combined cycle generating sets and chemistry, and in particular relates to a dosing and sampling system for multi-pressure waste heat boilers of combined cycle generating sets.

Background technique:

The combined cycle is a thermodynamic cycle that couples two or more thermomechanical power cycles together. Due to its advantages of high efficiency, low pollution, fast start and stop, and strong load variable capacity, it is receiving more and more attention and attention. application. Common combined cycle power generation units are mainly gas-steam combined cycle and integrated coal gasification combined cycle. Regardless of the type of combined cycle, the waste heat boiler is the core equipment used to recover the exhaust heat of the gas turbine and improve the thermal efficiency of the combined cycle generator set. In order to utilize the waste heat of the gas exhaust as much as possible (reduce the exhaust temperature of the waste heat boiler), the combined cycle unit generally does not use the feed water recuperation heater, and the preheating and deaeration of the condensed water are all completed inside the waste heat boiler. According to the gas turbine exhaust temperature, the steam-water system of the waste heat boiler usually adopts a multi-pressure or multi-pressure reheating scheme; according to the different deaeration methods, the steam-water system of the waste heat boiler mainly includes a built-in deaerator and a vacuum deoxidizer with a condenser Road deaerator two ways.

Due to the multi-pressure system and special steam-water parameters of the waste heat boiler of the combined cycle generator set, there are flow-accelerated corrosion in the low- and medium-pressure systems of the multi-pressure waste heat boiler, and the phosphate acid corrosion and steam carryover in the high- and medium-pressure systems affect the steam quality. Adverse effects, high water replenishment rate, and water quality control and outage maintenance of the waste heat boiler of the combined cycle unit under frequent start and stop operation conditions.

At present, the chemical dosing system and soda water quality control of waste heat boilers in domestic combined cycle power plants basically copy the dosing, sampling system and soda water quality control standards related to coal-fired thermal power units, and the dosing systems are mostly manual control. The effect is poor. It is necessary to propose a dosing and sampling system and a steam-water quality control method suitable for multi-pressure waste heat boilers according to the characteristics of the waste heat boiler system of the combined cycle generator set.

Utility model content:

The purpose of this utility model is to overcome the defects of dosing and steam water control technology in the steam-water system of the waste heat boiler of the combined cycle generating set, and provide a dosing and sampling system for the multi-pressure waste heat boiler of the combined cycle generating set, and clarify the key points Soda control parameters.

In order to achieve the above object, the utility model adopts the following technical solutions to realize:

A dosing and sampling system for multi-pressure waste heat boilers of combined cycle generator sets, including condensate pumps, iron removers or fine desalination devices, waste heat boiler heating surface systems, built-in deaerators, low-pressure steam drums, medium-pressure feed Water pumps, high-pressure feed water pumps, medium-pressure steam drums, high-pressure steam drums, steam turbine high-pressure cylinders, steam turbine medium-pressure cylinders, steam turbine low-pressure cylinders, condensers, and condensate heating wells; among them,

The condensed water is pressurized by the condensed water pump and enters the heating surface system of the waste heat boiler through the iron remover or fine desalting device; The steam drum, the low-pressure steam drum is used as the water tank of the built-in deaerator; the low-pressure feed water reaches saturation after being heated by the low-pressure evaporator. Lead to the low-pressure cylinder of the steam turbine; part of the saturated water in the low-pressure steam drum is used as the feed water of the medium-pressure and high-pressure systems, and then enters the medium-pressure economizer and high-pressure economizer after being pressurized by the medium-pressure feed water pump and the high-pressure feed water pump; The medium-pressure feedwater heated by the economizer enters the medium-pressure steam drum, and the medium-pressure feedwater reaches a saturated state after being heated by the medium-pressure evaporator. After the steam-water separation is realized in the medium-pressure steam drum, the medium-pressure saturated steam is introduced into the medium-pressure superheater for heating After that, medium-pressure superheated steam is formed, which is led to the inlet of the reheater and mixed with the exhaust steam of the high-pressure cylinder of the steam turbine, and after being heated by the reheater, high-temperature reheated steam is formed and led to the medium-pressure cylinder of the steam turbine; after being heated by the high-pressure economizer The high-pressure feed water enters the high-pressure steam drum, and the high-pressure feed water reaches saturation after being heated by the high-pressure evaporator. After the steam-water separation is realized in the high-pressure steam drum, the high-pressure saturated steam is introduced into the high-pressure superheater to be heated to form high-pressure superheated steam, and then led to the high-pressure steam turbine. cylinder; high-pressure superheated steam, reheated steam, and low-pressure superheated steam work in the steam turbine, and the exhausted steam enters the condenser to condense, and the condensed water falls into the hot well of the condenser and finally enters the condensed water pump to form a steam-water system cycle.

The further improvement of the utility model is that it also includes a desalinated water replenishment valve, and the replenishment water of the thermal system enters the condenser hot well through the desalinated water replenishment valve.

The further improvement of the utility model is that it also includes a gas turbine, and the exhaust gas of the gas turbine is discharged to the chimney after being cooled by the heating surfaces of the waste heat boiler heating surface systems at all levels.

The further improvement of the utility model is that the dosing point in the system is provided with an ammonia addition point for the outlet main pipe of the condensate pump or the outlet main pipe of the fine desalination device, an ammonia addition point for the inlet main pipe of the medium pressure feed water pump, and an ammonia addition point for the inlet main pipe of the high pressure feed water pump. Pipe ammonia dosing point, medium-pressure drum boiler water dosing point, high-pressure drum boiler water dosing point, ammonia dosing point before the desalination water supply valve, medium-pressure feed water pump inlet main pipe oxygen dosing point and high-pressure feed water pump inlet main pipe Oxygen point.

The further improvement of the utility model is that the sampling points in the system are provided with the sampling points of the outlet main pipe of the iron remover or the fine desalination device, the sampling points of the inlet of the low-pressure economizer or the condensate heater, the sampling points of the low-pressure drum boiler water, Medium pressure economizer inlet sampling point, medium pressure drum boiler water sampling point, high pressure economizer inlet sampling point, high pressure drum boiler water sampling point, low pressure drum outlet saturated steam sampling point, medium pressure drum outlet saturated steam Sampling point, sampling point of saturated steam at the outlet of high-pressure drum, sampling point of steam at the outlet of low-pressure superheater, sampling point of steam at the outlet of medium-pressure superheater, sampling point of steam at the outlet of high-pressure superheater, sampling point of steam at the outlet of reheater, low-pressure economizer or Sampling points at the outlet of the condensate heater, sampling points at the outlet of the medium-pressure economizer, and sampling points at the outlet of the high-pressure economizer.

The further improvement of the utility model is that it also includes the first to third condensate water ammonia addition metering pumps and the first to third feed water ammonia addition metering pumps; wherein, the condensate water ammonia addition system is equipped with 3 condensate water ammonia addition metering pumps, They are the first condensate water ammonia addition metering pump, the second condensate water ammonia addition metering pump, and the third condensate water ammonia addition metering pump, in which the first condensate water ammonia addition metering pump and the second condensate water ammonia addition metering pump are both The small-capacity pump, one for operation and one for standby, is used for dosing during the normal operation of the waste heat boiler; the third condensate ammonia dosing metering pump is a large-capacity pump, which is used for dosing during the startup and shutdown protection stages of the unit; the water supply and ammonia dosing system Configure three ammonia metering pumps, namely the first water supply ammonia metering pump, the second water supply ammonia metering pump and the third water supply ammonia metering pump.

The further improvement of the utility model is that the drum boiler water dosing system is also equipped with dosing pumps of different pressures and capacities, wherein, two medium-pressure drum boiler water dosing metering pumps are configured, that is, the first medium-pressure boiler water dosing pump Phosphate or sodium hydroxide metering pump and the second medium-pressure furnace water plus phosphate or sodium hydroxide metering pump; equipped with 2 high-pressure drum boiler water dosing metering pumps, that is, the first high-pressure furnace water plus phosphate or hydroxide The sodium metering pump and the second high-pressure furnace water plus phosphate or sodium hydroxide metering pump are both transported and prepared.

The further improvement of the utility model is that it also includes a control cabinet, wherein all input signals output control signals after the PLC application control algorithm in the control cabinet, and the control signals are respectively sent to different dosing pump outlet control valves to adjust the Dosing amount, to achieve the purpose of automatic control of ammonia and oxygen addition.

Compared with the prior art, the utility model has the following beneficial effects:

Improvements have been made to the dosing and sampling systems of the steam-water system of the multi-pressure waste heat boiler of the existing combined cycle generator set.

(1) Automatic dosing system: canceling the hydrazine addition system can completely solve the flow acceleration corrosion problem caused by hydrazine in the condensate and water supply system; set up an automatic ammonia addition system for condensate (fine desalination water), and propose a The controlled pH value parameter increases the pH value of the condensed water and the water supply system, and further improves the anti-corrosion performance of the system; the automatic water supply oxygenation system is set up, and the controllable dissolved oxygen parameter is proposed, which significantly reduces the iron content of the water supply system and improves The anti-corrosion performance of the system is improved; the improvement of these dosing systems can effectively achieve the beneficial effects of reducing the corrosion of condensate and water supply systems, reducing the iron content of the system, and reducing the amount of scaling in the boiler, effectively improving the safety, reliability and economic performance of the unit.

(2) Sampling system: The improvement of the sampling system has effectively achieved the precise monitoring of the corrosion of the system. These improvements have effectively solved the problem of accelerated corrosion of condensate and feedwater flow in multi-pressure waste heat boilers of combined cycle generator sets, reduced the iron content of condensate and feedwater systems, reduced the amount of scaling in boilers, and achieved accurate monitoring of system corrosion monitor.

The utility model is a simple, easy-to-operate, precise-control drug dosing and sampling system, which is especially suitable for multi-pressure waste heat boilers of combined cycle generator sets that are frequently started and stopped.

Description of drawings:

Figure 1 is a schematic diagram of the dosing and sampling points of the steam-water system of the multi-pressure waste heat boiler of the combined cycle generator set.

Equipment: 1-condensate pump; 2-iron remover or refined desalting device; 3-heating surface system of waste heat boiler; 4-built-in deaerator; 5-low pressure steam drum; Water pump; 8-medium pressure steam drum; 9-high pressure steam drum; 10-high pressure cylinder of steam turbine; 11-medium pressure cylinder of steam turbine; 12-low pressure cylinder of steam turbine; 13-condenser; 14-condensation water well; 15-Desalting and replenishing water valve.

Dosing point: 16-the ammonia addition point of the outlet main pipe of the condensate pump or the outlet main pipe of the refined desalination device (capacity increase); 17-the ammonia addition point of the inlet main pipe of the medium pressure feed water pump; Ammonia point; 19-Mid-pressure feed water pump inlet main pipe adding hydrazine point (cancelled); 20-High-pressure feed water pump inlet main pipe adding hydrazine point (cancelled); 21-Low pressure drum boiler water dosing point (cancelled); 22-Medium pressure drum boiler water dosing point; 23-High pressure drum boiler water dosing point; 24-Ammonia dosing point before the desalination and replenishment valve (newly added); 25-Medium pressure feed water pump inlet main pipe oxygen dosing point (newly added); 26-Oxygen addition point of the inlet main pipe of the high-pressure feed water pump (newly added).

Sampling point: 27-Sampling point of main pipe outlet of iron remover or fine desalting device; 28-Sampling point of inlet of low-pressure economizer or condensate heater; 29-Sampling point of low-pressure drum boiler water; 30-Medium pressure economizer Inlet sampling point; 31-medium pressure drum boiler water sampling point; 32-high pressure economizer inlet sampling point; 33-high pressure drum boiler water sampling point; 34-low pressure drum outlet saturated steam sampling point; 35-medium pressure Drum outlet saturated steam sampling point; 36-high pressure drum outlet saturated steam sampling point; 37-low pressure superheater outlet steam sampling point; 38-medium pressure superheater outlet steam sampling point; 39 high pressure superheater outlet steam sampling point; 40-reheater outlet steam sampling point; 41-low pressure economizer or condensate water heater outlet sampling point (new addition); 42-medium pressure economizer outlet sampling point (new addition); 43-high pressure economizer Export sampling point (new).

Figure 2 is a schematic diagram of the condensate, feed water and drum boiler water dosing system of the multi-pressure waste heat boiler of the combined cycle generator set.

Among them, 44-the first condensate water and ammonia metering pump; 45-the second condensate water and ammonia metering pump; 46-the third condensate water and ammonia metering pump; 47-the first water supply and ammonia metering pump; 48-the second water supply Ammonia metering pump; 49-the third feed water ammonia metering pump; 50-the first medium pressure furnace water plus phosphate or sodium hydroxide metering pump; 51-the second medium pressure furnace water plus phosphate or sodium hydroxide metering pump ; 52-the first high-pressure furnace water plus phosphate or sodium hydroxide metering pump; 53-the second high-pressure furnace water plus phosphate or sodium hydroxide metering pump.

Figure 3 is a schematic diagram of the feedwater oxygenation system for the multi-pressure waste heat boiler of the combined cycle generator set.

detailed description:

The following is an example of a built-in deaerator triple-pressure reheat drum waste heat boiler steam-water system dosing and sampling system, but the content of the utility model is not limited to this type of boiler, and it is also applicable to other types of drum boilers and DC boilers The same applies.

Figure 1 is a schematic diagram of dosing and sampling points in the steam-water system of a typical built-in deaerator triple-pressure reheat drum waste heat boiler of a combined cycle generator set. The condensed water is pressurized by the condensed water pump 1 and enters the heating surface system 3 of the waste heat boiler through the iron remover or fine desalting device 2; the pressurized condensed water first enters the condensed water heater or low-pressure economizer to be heated and then enters the built-in deaeration The low-pressure steam drum 5 is used as the water tank of the built-in deaerator 4; the low-pressure feed water reaches a saturated state after being heated by the low-pressure evaporator, and after the steam-water separation is realized in the low-pressure steam drum 5, the low-pressure saturated steam is introduced into the low-pressure After the superheater is heated, the low-pressure superheated steam is led to the low-pressure cylinder 12 of the steam turbine; part of the saturated water in the low-pressure steam drum 5 is used as the feed water of the medium-pressure and high-pressure systems, and then enters the medium-pressure system after being pressurized by the medium-pressure feed water pump 6 and high-pressure feed water pump 7 respectively. Economizer and high-pressure economizer; the medium-pressure feedwater heated by the medium-pressure economizer enters the medium-pressure steam drum 8, and the medium-pressure feedwater reaches saturation after being heated by the medium-pressure evaporator, and is realized in the medium-pressure steam drum 8 After steam-water separation, the medium-pressure saturated steam is introduced into the medium-pressure superheater to be heated to form medium-pressure superheated steam, and then led to the inlet of the reheater to mix with the exhaust steam from the high-pressure cylinder 10 of the steam turbine, and then heated by the reheater to form high-temperature reheated steam Lead to the medium pressure cylinder 11 of the steam turbine; the high-pressure feed water heated by the high-pressure economizer enters the high-pressure steam drum 9, and the high-pressure feed water reaches a saturated state after being heated by the high-pressure evaporator. The steam is introduced into the high-pressure superheater and heated to form high-pressure superheated steam, which is led to the high-pressure cylinder 10 of the steam turbine; the exhausted steam after the high-pressure superheated steam, reheated steam, and low-pressure superheated steam have done work in the steam turbine enters the condenser 13 to condense, and the condensed water It falls into the hot well 14 of the condenser and finally enters the condensate pump 1 to form a steam-water system circulation. The make-up water of the thermal system enters the hot well 14 of the condenser through the desalted water make-up valve 15 . The exhaust gas from the gas turbine is discharged to the chimney after being cooled by the heating surface system 3 of the waste heat boiler at all levels.

The dosing method of the waste heat boiler of the existing combined cycle generator set is: condensate and feed water are treated by adding ammonia and hydrazine, and the ammonia addition point is the outlet main pipe of the condensate pump or the ammonia addition point 16 of the outlet main pipe of the fine desalination device (some low pressure steam drum), medium pressure feed water pump inlet main pipe ammonia addition point 17, high pressure feed water pump inlet main pipe ammonia addition point 18, hydrazine dosing point is medium pressure feed water pump inlet main pipe addition hydrazine point 19 and high pressure feed water pump inlet main pipe ammonia addition point 19 Adding hydrazine point 20 to the water pump inlet main pipe; the drum boiler water is treated with phosphate, and the phosphate dosing points are the low-pressure drum boiler water dosing point 21, the medium-pressure drum boiler water dosing point 22 and the high-pressure steam drum Boiler water dosing point 23, the closed cooling water is treated by adding hydrazine, and the dosing point is the outlet of the closed cooling water pump.

The sampling points of the existing steam-water system generally include the sampling point 27 of the outlet main pipe of the iron remover or fine desalination device, the sampling point 28 of the inlet of the low-pressure economizer or the condensate heater, the sampling point 29 of the low-pressure drum boiler water, and the medium-pressure economizer Inlet sampling point 30, medium pressure drum boiler water sampling point 31, high pressure economizer inlet sampling point 32, high pressure drum boiler water sampling point 33, low pressure drum outlet saturated steam sampling point 34, medium pressure drum outlet saturated steam Sampling point 35, high pressure steam drum outlet saturated steam sampling point 36, low pressure superheater outlet steam sampling point 37, medium pressure superheater outlet steam sampling point 38, high pressure superheater outlet steam sampling point 39, reheater outlet steam sampling point 40 .

The improved dosing system is: cancel all hydrazine adding systems, that is, cancel the hydrazine point 19 (cancelled) at the inlet main pipe of the medium-pressure feed water pump, add hydrazine point 20 (cancelled) at the main pipe of the high-pressure feed water pump inlet and closed Dosing point of cooling water pump outlet main pipe. Condensate and feed water are treated by adding ammonia. The ammonia addition point is the outlet main pipe of the condensate pump or the ammonia addition point 16 of the outlet main pipe of the refined desalination device (capacity increases), and the ammonia addition point 17 and the ammonia addition point of the medium pressure feedwater pump inlet main pipe are reserved The ammonia addition point 18 of the inlet main pipe of the high-pressure feed water pump is only used as a backup. Increase the ammonia addition point 24 (new addition) before the desalination water supply valve, and at the same time expand the ammonia addition point 16 (capacity increase) of the outlet main pipe of the condensate pump or the outlet main pipe of the fine desalination device, which can meet the normal conditions of the waste heat boiler at the same time. Requirements for running dosing and starting and stopping protection dosing.

Drum boiler water is treated by adding phosphate or sodium hydroxide, canceling low-pressure drum boiler water dosing point (cancelled) 21, boiler water dosing point is only set at medium-pressure drum boiler water dosing point 22 and high-pressure steam drum water dosing point Pack furnace water dosing point 23.

If the unit is equipped with a condensate fine desalination device, the feed water of the waste heat boiler is treated with oxygen addition. In view of the high oxygen content of the low-pressure system, the oxygen addition point is set at the oxygen addition point 25 (newly added) of the main pipe of the medium pressure feed water pump inlet. Oxygen addition point 26 (newly added) at the inlet main pipe of the high-pressure feed water pump.

The improved sampling system is as follows: on the basis of retaining the original sampling points, add 27 sampling points for the main pipe outlet of the iron remover or fine desalination device, 30 sampling points for the inlet of the medium-pressure economizer, and 32 sampling points for the inlet of the high-pressure economizer point to monitor the flow-accelerated corrosion of the low-temperature heating surface.

Figure 2 is a schematic diagram of the chemical dosing system of the combined cycle generator set. The dosing system consists of three parts: condensate water, feed water ammonia dosing system and drum boiler water dosing system.

Condensed water and feed water ammonia addition system consists of ammonia solution tank, demineralized water inlet pipe, solution tank outlet valve group, ammonia gas absorber, flow calibration column, dosing metering pump group, metering pump outlet valve group, other valves, pipelines and Attachment composition. The condensate ammonia addition system is equipped with three condensate ammonia addition metering pumps, namely the first condensate ammonia addition metering pump 44, the second condensate ammonia addition metering pump 45, and the third condensate ammonia addition metering pump 46, of which the first condensate ammonia addition metering pump The water ammonia addition metering pump 44 and the second condensed water ammonia addition metering pump 45 are small-capacity pumps, one for operation and the other for standby, and are used for dosing during the normal operation of the waste heat boiler; the third condensate water and ammonia addition metering pump 46 is a large-capacity pump The pump is used for dosing during unit startup and shutdown protection. The water supply ammonia addition system is equipped with three ammonia addition metering pumps, namely the first water supply ammonia addition metering pump 47 , the second water supply ammonia addition metering pump 48 , and the third water supply ammonia addition metering pump 49 . Considering that the feed water pump inlet main pipe ammonia addition is only used as a backup, the normal one runs, and the two roads share a backup pump (the second feed water ammonia addition metering pump 48). The condensate water and feed water ammonia addition system are automatically controlled. The amount of ammonia addition to the main pipe at the outlet of the condensate pump or the outlet of the refined desalination device is controlled by the condensate flow rate and the conductivity of the low-pressure drum boiler water as the input signal of the control cabinet to control the opening of the valve at the outlet of the ammonia addition pump. The amount of ammonia added before the desalinated water replenishment valve is controlled by the desalinated water replenishment flow rate and the conductivity of condensed water as the input signal of the control cabinet to control the valve opening of the outlet of the ammonia pump; The flow rate of the medium pressure feedwater and the conductivity of the inlet feedwater of the medium pressure economizer, the flow rate of the high pressure feedwater and the conductivity of the inlet feedwater of the high pressure economizer are used as the input signals of the control cabinet to control the opening of the outlet regulating valve of the ammonia pump. Control the pH value of the condensed water after adding ammonia to be between 9.5 and 9.8; when adding oxygen, control the pH value of the condensed water at the outlet of refined desalination to be between 9.0 and 9.6. During the oxygenation treatment, the dissolved oxygen content in the inlet feed water of the medium and high pressure economizers should be controlled to be 30-150μg/L. The low-pressure drum boiler water sampling online chemical instrument in the sampling system is improved from the original conductivity Sc, pH value, and oxygen content O ₂ to conductivity Sc, hydrogen conductivity Cc, pH value, and oxygen content O ₂ .

Drum boiler water is treated by adding phosphate or sodium hydroxide. The steam drum boiler water dosing system consists of phosphate or sodium hydroxide solution tank, desalinated water inlet pipe, solution tank outlet valve group, flow calibration column, dosing It consists of pump group, metering pump outlet valve group, other valves, pipelines and accessories. The drum boiler water dosing system is equipped with dosing pumps of different pressures and capacities, and is equipped with 2 medium-pressure drum boiler water dosing metering pumps, that is, the first medium-pressure boiler water adding phosphate or sodium hydroxide metering pump 50 and the second Add phosphate or sodium hydroxide metering pump 51 to medium-pressure furnace water; configure 2 high-pressure drum boiler water-dosing metering pumps, that is, the first high-pressure furnace water plus phosphate or sodium hydroxide metering pump 52 and the second high-pressure furnace water Add phosphate or sodium hydroxide metering pump 53, all are one transport and one standby, to guarantee continuous dosing of boiler water.

Fig. 3 is a schematic diagram of the feed water oxygenation system of the triple-pressure waste heat boiler. If the combined cycle generator set is equipped with a condensate fine desalination device, the feed water can be treated with oxygen to reduce the fouling and corrosion of the steam water system. The waste heat boiler feed water oxygenation point is the main pipe of the inlet of the medium pressure feed water pump and the main pipe of the inlet of the high pressure feed water pump. The water supply oxygenation system consists of an oxygen cylinder station, a buffer tank, an oxygenation regulating valve group, a flow meter, a temperature measuring element, a pressure measuring element, a control valve, other valves, pipes and accessories. The feedwater oxygenation system is automatically controlled. The oxygen addition amount of the medium-pressure feedwater pump inlet main pipe is controlled by the medium-pressure feedwater flow rate and the medium-pressure economizer inlet oxygen content as the input signal of the control cabinet to control the opening of the oxygen-adding valve. The high-pressure feedwater pump inlet main pipe The amount of oxygen added to the pipe is controlled by the high-pressure feed water flow rate and the oxygen content at the inlet of the high-pressure economizer as the input signal of the control cabinet to control the opening of the oxygen-added regulating valve. The control index is: the dissolved oxygen content of the inlet feed water of medium pressure economizer and high pressure economizer is 30~150μg/L.

Claims (8)

1. A dosing and sampling system for a multi-pressure waste heat boiler of a combined cycle generator set is characterized by comprising a condensate pump (1), an iron remover or a fine desalting device (2), a waste heat boiler heating surface system (3), a built-in deaerator (4), a low-pressure steam pocket (5), a medium-pressure water feed pump (6), a high-pressure water feed pump (7), a medium-pressure steam pocket (8), a high-pressure steam pocket (9), a steam turbine high-pressure cylinder (10), a steam turbine medium-pressure cylinder (11), a steam turbine low-pressure cylinder (12), a condenser (13) and a condensate hot well (14); wherein,

the condensed water is pressurized by a condensed water pump (1) and then enters a waste heat boiler heating surface system (3) through an iron remover or a fine desalting device (2); the pressurized condensed water firstly enters a condensed water heater or a low-pressure economizer to be heated and then enters an internal deaerator (4) and a low-pressure steam pocket (5), and the low-pressure steam pocket (5) is used as a water tank of the internal deaerator (4); the low-pressure feed water is heated by a low-pressure evaporator to reach a saturated state, after steam-water separation is realized in a low-pressure steam drum (5), low-pressure saturated steam is introduced into a low-pressure superheater to be heated, and low-pressure superheated steam is introduced into a low-pressure cylinder (12) of the steam turbine; part of saturated water in the low-pressure steam drum (5) is used as feed water of a medium-pressure system and a high-pressure system, and is pressurized by a medium-pressure feed water pump (6) and a high-pressure feed water pump (7) and then enters a medium-pressure economizer and a high-pressure economizer; the medium-pressure feed water heated by the medium-pressure economizer enters a medium-pressure steam drum (8), the medium-pressure feed water is heated by a medium-pressure evaporator and reaches a saturated state, after steam-water separation is realized in the medium-pressure steam drum (8), the medium-pressure saturated steam is introduced into a medium-pressure superheater and is heated to form medium-pressure superheated steam, the medium-pressure superheated steam is introduced to an inlet of a reheater and is mixed with exhaust steam of a high-pressure cylinder (10) of the steam turbine, and high-temperature reheated steam is formed after the medium-pressure saturated steam is heated by the reheater and is introduced to a medium-; high-pressure feed water heated by a high-pressure economizer enters a high-pressure steam drum (9), the high-pressure feed water is heated by a high-pressure evaporator to reach a saturated state, after steam-water separation is realized in the high-pressure steam drum (9), high-pressure saturated steam is introduced into a high-pressure superheater to be heated to form high-pressure superheated steam, and the high-pressure superheated steam is introduced into a high-pressure cylinder (10) of a steam turbine; exhaust steam generated after the high-pressure superheated steam, the reheated steam and the low-pressure superheated steam work in the steam turbine enters a condenser (13) for condensation, condensed water falls into a condenser hot well (14) and finally enters a condensed water pump (1) to form steam-water system circulation.

2. The dosing and sampling system for the combined cycle power plant multi-pressure waste heat boiler according to claim 1, further comprising a demineralized water make-up valve (15), wherein the thermodynamic system make-up water enters the condenser hot well (14) through the demineralized water make-up valve (15).

3. The dosing and sampling system for the combined cycle generator set multi-pressure waste heat boiler as claimed in claim 1, characterized by further comprising a gas turbine, wherein the exhaust gas of the gas turbine is cooled by the heating surface of the heating surface system (3) of each waste heat boiler and then discharged to a chimney.

4. The dosing and sampling system for the multi-pressure waste heat boiler of the combined cycle generator set according to claim 1, characterized in that dosing points in the system are provided with a condensate pump outlet main pipe or a fine desalination device outlet main pipe dosing point (16), a medium-pressure feed pump inlet main pipe dosing point (17), a high-pressure feed pump inlet main pipe dosing point (18), a medium-pressure drum boiler water dosing point (22), a high-pressure drum boiler water dosing point (23), a desalination water supplementing valve front dosing point (24), a medium-pressure feed pump inlet main pipe oxygenation point (25) and a high-pressure feed pump inlet main pipe oxygenation point (26).

5. The dosing and sampling system for the multi-pressure waste heat boiler of the combined cycle generator set according to claim 1, wherein a sampling point in the system is provided with a sampling point (27) of an outlet main pipe of an iron remover or a fine desalination device, a sampling point (28) of an inlet of a low-pressure economizer or a condensate heater, a sampling point (29) of low-pressure drum boiler water, a sampling point (30) of an inlet of a medium-pressure economizer, a sampling point (31) of medium-pressure drum boiler water, a sampling point (32) of an inlet of a high-pressure economizer, a sampling point (33) of high-pressure drum boiler water, a sampling point (34) of low-pressure drum outlet saturated steam, a sampling point (35) of medium-pressure drum outlet saturated steam, a sampling point (36) of high-pressure drum outlet saturated steam, a sampling point (37) of low-pressure superheater outlet steam, a sampling point (38) of medium-pressure superheater outlet steam, a sampling point (39), a reheater outlet steam sampling point (40), a low pressure economizer or condensate heater outlet sampling point (41), a medium pressure economizer outlet sampling point (42), and a high pressure economizer outlet sampling point (43).

6. The dosing and sampling system for the combined cycle generator set multi-pressure waste heat boiler according to claim 1, further comprising first to third condensed water dosing pumps (44-46) and first to third feed water dosing pumps (47-49); the system comprises a condensate water ammoniating system, a waste heat boiler and a waste heat boiler, wherein the condensate water ammoniating system is provided with 3 condensate water ammoniating metering pumps, namely a first condensate water ammoniating metering pump (44), a second condensate water ammoniating metering pump (45) and a third condensate water ammoniating metering pump (46), wherein the first condensate water ammoniating metering pump (44) and the second condensate water ammoniating metering pump (45) are small-capacity pumps, and are used for dosing in the normal operation stage of the waste heat boiler; the third condensed water ammonia adding metering pump (46) is a large-capacity pump and is used for adding chemicals in the protection stage of starting and stopping the unit; the water supply ammonia adding system is provided with 3 ammonia adding metering pumps which are a first water supply ammonia adding metering pump (47), a second water supply ammonia adding metering pump (48) and a third water supply ammonia adding metering pump (49).

7. The dosing and sampling system for the multi-pressure waste heat boiler of the combined cycle generator set according to claim 6, characterized in that the drum boiler water dosing system is further provided with dosing pumps with different pressures and capacities, wherein 2 medium-pressure drum boiler water dosing metering pumps are provided, namely a first medium-pressure boiler water dosing phosphate or sodium hydroxide metering pump (50) and a second medium-pressure boiler water dosing phosphate or sodium hydroxide metering pump (51); 2 high-pressure drum furnace water dosing metering pumps are arranged, namely a first high-pressure furnace water phosphate or sodium hydroxide metering pump (52) and a second high-pressure furnace water phosphate or sodium hydroxide metering pump (53), which are operated at one time and are standby at the other time.

8. The dosing and sampling system for the multi-pressure waste heat boiler of the combined cycle generator set according to claim 7, further comprising a control cabinet, wherein all input signals output control signals after a PLC in the control cabinet applies a control algorithm, and the control signals are respectively sent to outlet control valves of different dosing pumps to adjust dosing amounts at different positions and achieve the purpose of automatically controlling ammonia and oxygen addition.