CN214038473U

CN214038473U - Boiler flue gas waste heat utilization system for back pressure steam turbine

Info

Publication number: CN214038473U
Application number: CN202023328840.0U
Authority: CN
Inventors: 李仁�; 张方炜; 钟文英
Original assignee: North China Power Engineering Co Ltd of China Power Engineering Consulting Group
Current assignee: North China Power Engineering Co Ltd of China Power Engineering Consulting Group; North China Power Engineering Beijing Co Ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-08-24
Anticipated expiration: 2030-12-30

Abstract

The utility model discloses a boiler flue gas waste heat utilization system for a back pressure steam turbine, which comprises a cold source working medium and a main pipeline of a deaerator, wherein a branch pipeline and a second check valve are sequentially arranged on the main pipeline; a first check valve is arranged on the branch pipeline, and an outlet pipeline of the first check valve is connected with the low-temperature economizer through a circulating booster pump unit; the water outlet of the low-temperature economizer is also connected with a hot water recirculation temperature adjusting pipeline, a heating system external heat pipeline and a heating system internal heat recovery pipeline in parallel; the flue gas waste heat utilization system has simple configuration, complete functions, safety, reliability, low investment and very convenient installation, operation and later maintenance; not only can satisfy the low cooling effect of economizing, but also does not influence the performance of the original water inlet pipeline of the deaerator.

Description

Boiler flue gas waste heat utilization system for back pressure steam turbine

Technical Field

The utility model belongs to the power engineering field for solve the boiler flue gas waste heat recovery problem supporting with back pressure steam turbine.

Background

The improvement of the boiler efficiency is always an important responsibility of a thermal power engineer, and the boiler efficiency depends on various heat losses of the boiler, including exhaust heat loss, chemical incomplete combustion heat loss, mechanical incomplete combustion heat loss, boiler heat dissipation loss, slag discharge heat loss and the like. The heat loss of the exhaust gas is the loss caused by physical heat of the exhaust gas of the boiler, and is usually the largest heat loss of the boiler, so reducing the heat loss of the exhaust gas is the preferred option for improving the efficiency of the boiler.

And the recovery of the waste heat of the flue gas is an effective means for reducing the heat loss of the flue gas. Generally, the recovered flue gas waste heat can be used for heating cold air at the inlet of the air preheater, so that the corrosion and scaling of the air preheater can be avoided; the condensed water of the steam turbine is heated, so that part of the low-pressure heater can be replaced by the condensed water for regenerative steam extraction, and the power of the steam turbine is increased, thereby improving the thermal economy of the unit and reducing the coal consumption for power generation.

When the system adopts the back pressure turbine, because the back pressure turbine does not have the condensate water, therefore need look for new cold source working medium and retrieve the flue gas waste heat. Usually, demineralized water is adopted as a cold source working medium of the back pressure turbine to supplement water for the deaerator, and the demineralized water can be heated before entering the deaerator, so that steam for deaerating and heating can be saved, and further the heat economy of the back pressure turbine unit is improved.

SUMMERY OF THE UTILITY MODEL

The utility model discloses to the characteristics of back pressure steam turbine no condensate water, the configuration problem of solving boiler flue gas waste heat recovery system is proposed, and this system both can satisfy the low cooling effect that economizes, does not influence the former inlet channel's of oxygen-eliminating device performance again.

The technical means adopted by the utility model are as follows.

A boiler flue gas waste heat utilization system for a back pressure steam turbine comprises a main pipeline from cold source working media to a deaerator, and is characterized in that a branch pipeline and a second check valve are sequentially arranged on the main pipeline; a first check valve is arranged on the branch pipeline, and an outlet pipeline of the first check valve is connected with the low-temperature economizer through a circulating booster pump unit; the water outlet of the low-temperature economizer is also connected with a hot water recirculation temperature adjusting pipeline in parallel: a first flowmeter and a recirculation flow regulating valve are arranged on the circulating booster pump unit, and a water outlet of the circulating booster pump unit is connected with a water inlet of the circulating booster pump unit; thermal system external heat pipe: the water outlet of the first check valve is connected with the water outlet of the first check valve; and a heat recovery pipeline in the thermodynamic system: the water outlet of the first check valve is connected with the water outlet of the second check valve.

Furthermore, a water consumption regulating valve group and a waste heat user are arranged on the external heat pipeline of the thermodynamic system.

Furthermore, a second flowmeter and an internal heat water supply flow regulating valve set are arranged on the internal heat recovery pipeline of the thermodynamic system.

Furthermore, the communication point of the main pipeline and the branch pipeline is a low-pressure-saving constant-pressure cooling water replenishing point; and the communication point of the main pipeline and the heat recovery pipeline in the thermodynamic system is a low-energy-saving cooling water return point.

Furthermore, the outlet water temperature of the low-temperature economizer is 10 ℃ lower than the corresponding water saturation temperature of the circulating booster pump under the inlet pressure.

Furthermore, an accident-state steam exhaust safety valve is arranged on a water outlet pipeline of the low-temperature economizer, the discharge capacity of the steam exhaust safety valve is not less than the low-water-saving-side vaporization output, and the discharge pressure is less than the design pressure of a water-side system.

Furthermore, a water discharge safety valve and a water supply regulating valve set are arranged on a main pipeline from the low-temperature water-saving cooling return point to the deaerator.

Furthermore, the water outlet of the drainage safety valve is connected to a drainage flash tank or a fixed drainage flash tank.

Furthermore, the cold source working medium is chemical desalted water.

The utility model discloses produced beneficial effect.

1. Flue gas waste heat utilization system, through the design of arranging and moving towards the pipeline, make the boiler exhaust heat loss always can reduce. The utility model ensures that the low-temperature economizer does not corrode on the one hand on the basis of not influencing the performance of the original water supply pipeline of the deaerator; on one hand, the heat supply requirement of users outside the thermodynamic system is ensured; on the other hand, the system can also be used for recovering internal heat of a thermodynamic system, so that the temperature of desalted water entering the deaerator is increased.

2. To back pressure steam turbine, adopt the utility model discloses afterwards, because boiler exhaust fume heat loss always can reduce for the heat economy nature of this unit improves greatly, has reduced the electricity generation coal consumption.

3. Flue gas waste heat utilization system configuration simple, multiple functional, safe and reliable, the investment is low, installation, operation and later maintenance are all very convenient.

Drawings

Fig. 1 is a piping layout diagram of the present invention.

Detailed Description

The boiler needs working medium for low-energy-saving heat recovery, and the back pressure turbine only can utilize chemical desalted water due to no condensed water, so that a system needs to be designed according to specific conditions. The utility model provides a boiler flue gas waste heat utilization system for back pressure steam turbine. The chemical demineralized water of the system is led out and led back on a conventional pipeline, so that the low-temperature cooling effect is ensured, the performance of the original water inlet pipeline of the deaerator is not influenced, the heat utilization requirement of waste heat users can be met, the purpose of reducing the heat loss of boiler exhaust smoke is realized, the heat economy of a unit is greatly improved, and the coal consumption for power generation is reduced. The utility model discloses a pipeline configuration and system application specifically explain as follows.

Please refer to fig. 1, which is a diagram illustrating a pipeline configuration according to the present invention. As shown in the figure, a branch pipeline 2 and a second check valve 10 are sequentially arranged on a main pipeline 1 from a cold source working medium to a deaerator 5; meanwhile, a first check valve 20 is arranged on the branch pipeline 2, and an outlet pipeline of the first check valve 20 is connected with the low-temperature economizer 4 through a circulating booster pump unit 3; the water outlet of the low-temperature economizer 4 is also connected with at least three pipelines in parallel, namely a hot water recirculation temperature adjusting pipeline 41, a heating system external heat pipeline 42 and a heating system internal heat recovery pipeline 43.

A water outlet pipeline of the hot water recirculation temperature regulating pipeline 41 is connected with a water inlet pipeline of the circulation booster pump unit 3, and a first flow meter 411 and a recirculation flow regulating valve 412 are arranged on the hot water recirculation temperature regulating pipeline 41, wherein the first flow meter 411 is used for monitoring the recirculation amount in the hot water recirculation temperature regulating pipeline 41. The recirculation amount of hot water in the pipeline is adjusted by a recirculation flow adjusting valve 412 according to the requirement of lowest wall temperature for low cost and no corrosion. Preferably, the outlet water temperature of the low-temperature economizer 4 is lower than the corresponding water saturation temperature of the circulating booster pump under the inlet pressure by about 10 ℃.

The water outlet pipeline of the thermal system external heat pipeline 42 is connected with the water outlet pipeline of the first check valve 20. The heating system external heat pipeline 42 is also provided with a water consumption regulating valve group 421 and a waste heat user 422, and the heat consumption requirements of the heating system external users can be met by regulating the fluid in the pipeline through the water consumption regulating valve group 421.

And a water outlet pipeline of the heat recovery pipeline 43 in the thermodynamic system is connected with a water outlet pipeline of the second check valve 10. The heat recovery pipeline 43 in the thermal system is provided with a second flow meter 431 and an internal heat water supply flow regulating valve set 432. Wherein, the second flow meter 431 is used for monitoring and calculating the heat flow; the internal heat water supply flow regulating valve set 432 is set for regulating the flow of hot water during internal heat water supply.

Preferably, the communication point of the main pipeline 1 and the branch pipeline 2 is a low-pressure-saving constant-pressure cooling water replenishing point; the connection point of the main pipeline 1 and the heat recovery pipeline 43 in the thermodynamic system is a low-energy-saving cooling water return point.

In a preferred embodiment of the present invention, the water outlet pipeline of the low-temperature economizer 4 is further provided with an emergency steam relief valve 40, the discharge capacity of which is not less than the low-water-saving side vaporization output, and the discharge pressure is less than the design pressure of the water side system.

In a preferred embodiment of the present invention, a water discharge safety valve 6 and a water supply regulating valve group 8 are disposed on the main pipeline 1 from the low-temperature cooling return point to the deaerator 5. Wherein, the water outlet of the drainage safety valve 6 is connected to a drainage flash tank 71 or a fixed drainage flash tank 72. When the system is over-pressurized, a small amount of water is discharged to a drain flash tank 71 or a fixed displacement flash tank 72.

In a preferred embodiment of the present invention, the cold source working medium is chemical desalted water.

In a preferred embodiment of the present invention, the circulating booster pump unit 3 may be set as a parallel circulating pump unit for one use and one standby as required. Meanwhile, a blocking valve 9 can be additionally arranged on the pipeline according to the requirement. For example, the circulation pump is provided with a block valve 9 in front of and behind it, and the pump can be serviced when the block valve 9 is closed. For another example, a closing valve (not shown) may be additionally disposed in the water consumption regulating valve group 421 disposed in front of the waste heat consumer 422, and a closing valve 11 is disposed at the outlet of the waste heat consumer 422; when the front closing valve and the outlet closing valve 11 of the waste heat user 422 are closed, the waste heat user 422 can be closed. Similarly, as shown in fig. 1, a block valve 9 may be further disposed on an outlet pipeline of the heat recovery pipeline 43 in the thermodynamic system.

The installation setting of all kinds of valves, pump equipment, flow control and adjusting device such as recirculation flow control valve 412, circulation booster pump unit 3, water consumption regulating valve group 421, interior heat water supply flow control valves 432, feed water regulating valve group 8, block valve 9, shut-off valve 11, relief valve, flowmeter is prior art, does not do here and give unnecessary details.

The utility model provides an among the boiler flue gas waste heat utilization system for back pressure steam turbine, pipeline configuration and system operation can be expounded as follows: and the chemical demineralized water flows into the circulating booster pump unit 3 and the low-temperature economizer 4 in sequence along part or all of the main pipeline 1 through the second check valve 10, and the flue gas heat exchange is carried out in the low-temperature economizer 4. The heat exchange water flowing out of the water outlet of the low-temperature economizer 4 is mainly divided into 3 flow directions for utilizing the waste heat of the flue gas. One flow direction of the hot water is returned to the water inlet pipeline of the circulating booster pump unit 3 along the hot water recycling temperature adjusting pipeline 41; the flow direction can be further adjusted by the recirculation flow control valve 412 to meet the system operation requirements and ensure that the requirements of low cost and no corrosion on the inlet water temperature are met.

The two flows enter the thermal system external heat pipeline 42 to meet the heat demand of the waste heat consumer 422. Also, the heat demand of the waste heat consumer 422 can be adjusted according to the water consumption adjusting valve set 421.

Boiler flue gas waste heat utilization system in, satisfying its two to with under the condition of hot demand, abundant part then flows in this system in the thermal power system heat recovery pipeline 43, this is its three flow directions. The flow direction increases the temperature of the fluid entering the deaerator 5, and a good deaerating effect can be achieved when the steam usage amount is reduced.

Based on this, the utility model discloses on the basis that does not influence former oxygen-eliminating device water intake pipe characteristic, carry out ingenious arrangement to the pipeline, satisfied the requirement that the low temperature economizer does not corrode simultaneously and thermodynamic system exterior user's heat supply demand, make the flue gas waste heat obtain the utilization of maximize. In addition, the configuration of three flow directions of the water outlet of the low-temperature economizer greatly reduces the heat loss of boiler exhaust gas, so that the waste heat of the flue gas can be utilized to the maximum, the heat economy of the unit is greatly improved, and the coal consumption of power generation is reduced.

Claims

1. A boiler flue gas waste heat utilization system for a back pressure steam turbine comprises a main pipeline (1) from a cold source working medium to a deaerator (5), and is characterized in that a branch pipeline (2) and a second check valve (10) are sequentially arranged on the main pipeline (1); a first check valve (20) is arranged on the branch pipeline (2), and an outlet pipeline of the first check valve (20) is connected with the low-temperature economizer (4) through the circulating booster pump unit (3); the water outlet of the low-temperature economizer (4) is also connected in parallel with:

hot water recirculation temperature regulating line (41): a first flow meter (411) and a recirculation flow regulating valve (412) are arranged on the circulating booster pump unit, and the water outlet of the circulating booster pump unit is connected with the water inlet of the circulating booster pump unit (3);

thermal system external heat pipe (42): the water outlet of the first check valve (20) is connected with the water outlet of the first check valve;

thermal system heat recovery line (43): the water outlet of the first check valve is connected with the water outlet of the second check valve (10).

2. The boiler flue gas waste heat utilization system for the back pressure turbine as claimed in claim 1, wherein the thermal system external heat pipe (42) is provided with a water consumption regulating valve group (421) and a waste heat user (422).

3. The boiler flue gas waste heat utilization system for the back pressure turbine as claimed in claim 1, wherein a second flow meter (431) and an internal hot water supply flow regulating valve group (432) are arranged on the heat recovery pipeline (43) in the thermodynamic system.

4. The boiler flue gas waste heat utilization system for a back pressure turbine according to any one of claims 1 to 3, characterized in that the connection point of the main pipeline (1) and the branch pipeline (2) is a low-pressure-saving and constant-pressure cooling water supply point; and the communication point of the main pipeline (1) and the heat recovery pipeline (43) in the thermodynamic system is a low-energy-saving cooling water return point.

5. The boiler flue gas waste heat utilization system for a back pressure turbine as claimed in claim 4, characterized in that the leaving water temperature of the low temperature economizer (4) is 10 ℃ lower than the corresponding water saturation temperature at the inlet pressure of the circulating booster pump.

6. The boiler flue gas waste heat utilization system for a back pressure turbine according to claim 4, characterized in that an emergency state steam exhaust safety valve (40) is arranged on a water outlet pipeline of the low-temperature economizer (4), the exhaust capacity of the system is not less than the low-water-saving side vaporization output, and the exhaust pressure is less than the design pressure of a water side system.

7. The boiler flue gas waste heat utilization system for a back pressure turbine according to claim 4, characterized in that a water discharge safety valve (6) and a water feed regulating valve group (8) are arranged on the main pipeline (1) from the low-temperature-saving cooling water return point to the deaerator (5).

8. The boiler flue gas waste heat utilization system for a back pressure turbine according to claim 7, characterized in that the water outlet of the water discharge safety valve (6) is connected to a water discharge flash tank (71) or a fixed discharge flash tank (72).

9. The boiler flue gas waste heat utilization system for a back pressure turbine as claimed in claim 4, wherein the cold source working medium is chemical demineralized water.