System for increasing starting cold air temperature of boiler

Abstract

The utility model discloses a system for increasing the temperature of boiler starting cold air, which comprises a boiler condensate water tank which is respectively connected with a primary air heater and a secondary air heater through a drainage starting pump. Drain pipelines of the primary air heater and the secondary air heater are respectively connected with a boiler drain flash tank, a unit drain tank and a steam turbine drain flash tank; a large amount of heat in a working medium discharged by a boiler can be fully utilized to heat primary air and secondary air, the temperature of air fed into the boiler can be increased, the steam supply amount of the auxiliary steam header can be effectively reduced, particularly, a starting unit for supplying auxiliary steam by starting the boiler is adopted, the steam supply amount of the auxiliary steam header is reduced, and the output of starting the boiler can be obviously reduced; therefore, fuel consumption for starting the boiler is reduced, and starting cost is reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of boiler cold air temperature regulation, and in particular relates to a system for improving the cold air temperature at boiler startup. Background Art

[0002] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] In recent years, with the intensification of global warming, energy conservation and emission reduction have become the consensus of the international community. The startup of large ultra-supercritical (super) units requires a large amount of water, electricity, oil, coal, steam and other resources, and takes a long time, resulting in the risk of this stage being much higher than the normal operation period of the unit. The oxide scale shedding and solid particle erosion problems unique to ultra-supercritical (super) units also mainly occur in this stage. In addition, in the general startup stage, due to the strong viscosity of oil smoke under incomplete combustion, in order to prevent its contamination of the electrostatic precipitator plates, electrostatic precipitators are not allowed to be used during the pure fuel oil and kerosene mixed combustion stage, which greatly increases the pollutant emissions in this stage.

[0004] When the direct-flow boiler of an ultra-supercritical unit is started, due to the limitation of the starting flow rate, the unit is in wet operation at the initial stage of startup, and there is a large amount of hot water in the condenser water tank of the boiler expansion tank. In the prior art, there are two main ways to discharge hot water: one is to discharge it to the unit drainage tank or industrial wastewater system, resulting in heat waste; the other is to discharge it to the steam turbine condenser, which wastes heat and also increases the plant power consumption rate and consumes more energy due to the reduction of the condenser vacuum. Both of these arrangements fail to fully utilize the heat discharged by the startup system, resulting in heat waste.

[0005] In addition, during the startup phase of the unit, a large number of equipment and systems such as the turbine shaft seal, air preheater soot blower, deaerator heating, primary air heater, secondary air heater, etc. require auxiliary steam, while the conventional startup boiler has a limited steam supply and cannot meet the steam supply needs of all users at the same time, or the steam supply capacity of some users is insufficient, so the primary air heater, secondary air heater, etc. cannot be put into use, resulting in a very low air temperature at the air preheater inlet, especially in winter, the comprehensive cold section temperature of the air preheater is very low, resulting in low-temperature corrosion of the air preheater, affecting the heat exchange efficiency of the air preheater. Utility Model Content

[0006] The utility model aims to provide a system for increasing the temperature of cold air when a boiler is started, which can improve the recycling rate of water while recovering heat through a heater, thereby achieving the purpose of saving water.

[0007] In order to achieve the above purpose, the utility model is implemented through the following technical solutions:

[0008] In the first aspect, an embodiment of the utility model provides a system for increasing the temperature of the cold air when a boiler is started, characterized in that it includes a boiler condensate tank, which is respectively connected to a primary air heater and a secondary air heater through a drain starting pump, and the drain pipes of the primary air heater and the secondary air heater are respectively connected to the boiler drain expansion tank, the unit drain tank, and the steam turbine drain expansion tank.

[0009] As a further technical solution, the primary air heater and the secondary air heater are also connected to an auxiliary steam pipeline.

[0010] As a further technical solution, a heater drain valve group is provided on the drain pipes of the primary air heater and the secondary air heater.

[0011] As a further technical solution, the air outlets of the primary air heater and the secondary air heater are connected to the air inlet of the boiler through an air preheater.

[0012] As a further technical solution, a drain pipe and an overflow pipe are also provided on the boiler condensate water tank, and both the drain pipe and the overflow pipe are connected to the unit drainage trough.

[0013] As a further technical solution, two drain pipes are arranged on the boiler condensate tank, the two drain pipes are arranged in parallel, and each drain pipe is provided with a drain starting pump and a valve.

[0014] As a further technical solution, the two drain pipes are connected in parallel and then divided into two routes, one to the boiler heater and the other to the turbine condenser.

[0015] As a further technical solution, the primary air heater and the secondary air heater are arranged in parallel, and there are two primary air heaters and two secondary air heaters each arranged in parallel.

[0016] As a further technical solution, during the hot open flushing stage, the drain pipes of the primary air heater and the secondary air heater are connected to the unit drain tank.

[0017] As a further technical solution, during the closed flushing or wet operation stage, the drain pipes of the primary air heater and the secondary air heater are connected to the boiler drain expansion tank or the steam turbine drain expansion tank.

[0018] The beneficial effects of the above-mentioned embodiments of the utility model are as follows:

[0019] The system for increasing the temperature of the cold air at the start of the boiler provided by the utility model can make full use of the large amount of heat in the boiler exhaust medium to heat the primary and secondary air, increase the air temperature sent to the boiler, improve the combustion environment in the furnace, make the fuel burn more fully, reduce the accumulation of unburned combustibles in the tail flue, and reduce the risk of secondary combustion at the tail of the boiler. Heating the primary and secondary air by the boiler exhaust medium can effectively reduce the steam supply of the auxiliary steam header, especially for the start-up unit that uses the start-up boiler to supply auxiliary steam. Reducing the steam supply of the auxiliary steam header can significantly reduce the output of the start-up boiler, thereby reducing the fuel consumption of the start-up boiler and reducing the start-up cost.

[0020] The utility model provides a system for increasing the temperature of the cold air when the boiler is started. While increasing the air temperature and improving the combustion environment, it can shorten the time for fuel injection, put the pulverizing system into operation as soon as possible, reduce the amount of fuel, shorten the start-up time of the boiler, put the unit into production operation as soon as possible, reduce the material consumption during the start-up process of the unit, and reduce the start-up cost. It can also put the environmental protection department into operation as soon as possible, reduce the emission of pollutants, and be beneficial to environmental protection.

[0021] The utility model provides a system for increasing the temperature of cold air at boiler startup. During the hot flushing process of the boiler, the discharge amount of the boiler working fluid is 30% of the rated evaporation amount of the boiler. After the discharged working fluid passes through the atmospheric expansion tank, the working fluid temperature is about 100°C. A large amount of working fluid contains a large amount of heat. Under the action of the starting drain pump, the working fluid enters the primary and secondary air heaters to increase the inlet air temperature of the boiler, so that the boiler can achieve the purpose of accelerating startup. The utility model has the advantages of less operation, low cost and high efficiency, and is suitable for the cold startup mode of a DC boiler unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0023] Figure 1 It is a schematic diagram of the pipe connection at the boiler condensing water tank in the system for increasing the temperature of the cold air when the boiler is started in the utility model;

[0024] Figure 2 The utility model is a schematic diagram of the pipeline connection of the heater in the system for increasing the temperature of the cold air when the boiler is started.

[0025] The schematic diagram is for illustrative purposes only;

[0026] Among them, 1. boiler condensate tank; 2. first drain pipe; 3. second drain pipe; 4. drainage pipe; 5. overflow pipe; 6. first drain start pump; 7. second drain start pump; 8. first primary air heater; 9. second primary air heater; 10. first secondary air heater; 11. second secondary air heater; 12. first drain valve group; 13. second drain valve group; 14. third drain valve group; 15. fourth drain valve group; 16. primary air heater drain pipe; 17. secondary air heater drain pipe. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0028] Example 1

[0029] In a typical implementation of the present invention, Figure 1 and Figure 2 As shown, a system for increasing the temperature of cold air when a boiler is started is provided, including a boiler condensate water tank, wherein the boiler condensate water tank is respectively connected to a primary air heater and a secondary air heater through a drain start pump, and the drain pipes of the primary air heater and the secondary air heater are respectively connected to a boiler drain expansion tank, a unit drain tank, and a steam turbine drain expansion tank, and the hot water in the boiler condensate water tank is used to provide heat for the primary air heater and the secondary air heater to heat the primary air and the secondary air, thereby increasing the temperature of the air sent into the boiler, improving the combustion environment in the furnace, and reducing the use of steam.

[0030] In this embodiment, the primary air heater and the secondary air heater are also connected to an auxiliary steam pipe. When the hot water temperature in the boiler condensate tank is low, the auxiliary steam provided by the auxiliary steam pipe increases the air temperature.

[0031] In this embodiment, the primary air heater and the secondary air heater are arranged in parallel, and two primary air heaters and two secondary air heaters are arranged in parallel, and heater trap valve groups are arranged on the drain pipes of the primary air heater and the secondary air heater. Specifically, the primary air heater includes a first primary air heater 8 and a second primary air heater 9, the first primary air heater 8 and the second primary air heater 9 are arranged in parallel, the first primary air heater 8 is provided with a first trap valve group 12, and the second primary air heater 9 is provided with a second trap valve group 13; the secondary air heater includes a first secondary air heater 10 and a second secondary air heater 11, the first secondary air heater 10 is provided with a third trap valve group 14, and the second secondary air heater 11 is provided with a fourth trap valve group 15. The drain pipes of the first primary air heater 8 and the second primary air heater 9 are merged and connected to the boiler drain expansion tank, the unit drain tank and the steam turbine drain expansion tank respectively through the primary air heater drain pipe 16. The drain pipes of the first secondary air heater 10 and the second secondary air heater 11 are merged and connected to the boiler drain expansion tank, the unit drain tank and the steam turbine drain expansion tank respectively through the secondary air heater drain pipe 17. Corresponding valves are provided on each pipe to adjust the flow direction and select the drain flow direction.

[0032] In this embodiment, the air outlets of the primary air heater and the secondary air heater are connected to the air inlet of the boiler through the air preheater, the primary air and the secondary air exchange heat with hot water in the heater, the primary air is heated, and the heated primary hot air enters the air preheater; the primary hot air temperature of the air preheater and the comprehensive cold section temperature of the primary and secondary air sides are increased, the secondary air is heated, and the heated secondary hot air enters the air preheater, increasing the secondary hot air temperature of the air preheater and the comprehensive cold section temperature of the secondary and secondary air sides.

[0033] In this embodiment, a drain pipe 4 and an overflow pipe 5 are further provided on the boiler condensate water tank 1, and both the drain pipe 4 and the overflow pipe 5 are connected to the drainage trough of the unit.

[0034] In this embodiment, two drain pipes are arranged on the boiler condensate tank 1, including a first drain pipe 2 and a second drain pipe 3. The first drain pipe 2 is provided with a first drain starting pump 6, and the second drain pipe 3 is provided with a second drain starting pump 7. The two drain pipes are arranged in parallel, and each drain pipe is also provided with valves and other components. By setting up two drain pipes, one is to increase the maximum drain flow rate, and the other is that one of the drain pipes can be used as a backup. When one drain pipe is damaged, the other drain pipe can be activated, and the normal use of the system is not affected.

[0035] Furthermore, after the two drain pipes are connected in parallel and merged, they are divided into two routes, one to the boiler heater and the other to the turbine condenser.

[0036] The system for increasing the temperature of cold air when starting a boiler provided by the utility model has the following working process:

[0037] During the hot open flushing stage of the boiler, the working medium in the boiler condensate tank enters the primary and secondary air heaters and is discharged to the unit drain tank through the drain pipe, and then pumped to the chemical for treatment. During the hot closed flushing and wet operation stage, the working medium in the boiler condensate tank passes through the primary and secondary air heaters and is discharged to the boiler drain expansion tank or steam turbine drain expansion tank through the drain pipe, and is recycled again through the condensate pump after the condenser is cooled.

[0038] Take the recent unit startup on June 13, 2023 as an example. During the hot flushing of the boiler, the temperature of the boiler condensing water tank is 99.1℃, while the wind temperature of the primary and secondary air at the inlet of the air preheater is between 35℃-40℃, and the temperature difference between the working medium and the wind temperature is about 60℃. If in winter, the outdoor temperature is below 0℃, the temperature difference between the two can reach about 100℃, and the boiler feed water flow rate during the hot flushing stage is 30% of the rated flow rate of the boiler, which has huge heat storage. While utilizing the heat of the boiler working medium, it can also reduce the steam supply of the startup boiler, reduce the startup boiler output, and achieve the purpose of energy saving.

[0039] The utility model provides a system for increasing the temperature of cold air when a boiler is started. Under the condition of the original equipment, a water supply pipe from the outlet of a starting drain pump to the primary and secondary air heaters is added, and the pipes and valves of the four heater drain pipes are connected to the unit drainage trough and the boiler drain expansion tank. While recovering heat through the heater, the recycling rate of water can be improved, thereby achieving the purpose of saving water.

[0040] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A system for increasing the temperature of cold air when a boiler is started, characterized in that: It includes a boiler condensate water tank, which is connected to a primary air heater and a secondary air heater respectively through a drain start pump. The drain pipes of the primary air heater and the secondary air heater are connected to a boiler drain expansion tank, a unit drainage tank, and a steam turbine drain expansion tank respectively.

2. The system for increasing the boiler startup cold air temperature according to claim 1, characterized in that: The primary air heater and the secondary air heater are also connected to the auxiliary steam pipeline.

3. The system for increasing the boiler startup cold air temperature according to claim 1, characterized in that: Heater drain valve groups are provided on the drain pipes of the primary air heater and the secondary air heater.

4. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: The air outlets of the primary air heater and the secondary air heater are connected to the air inlet of the boiler through the air preheater.

5. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: The boiler condensate water tank is also provided with a drain pipe and an overflow pipe, and both the drain pipe and the overflow pipe are connected to the drainage trough of the unit.

6. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: The boiler condensate water tank is provided with two drain pipes, the two drain pipes are arranged in parallel, and each drain pipe is provided with a drain start pump and a valve.

7. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 6, characterized in that: After the two drain pipes are connected in parallel and merged, they are divided into two routes, one going to the boiler heater and the other going to the turbine condenser.

8. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: The primary air heater and the secondary air heater are arranged in parallel, and there are two primary air heaters and two secondary air heaters each arranged in parallel.

9. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: During the hot open flushing stage, the drain pipes of the primary air heater and the secondary air heater are connected to the unit drain tank.

10. The system for increasing the temperature of the cold air when the boiler is started as claimed in claim 1, characterized in that: During the closed flushing or wet operation stage, the drain pipes of the primary air heater and the secondary air heater are connected to the boiler drain expansion tank or the steam turbine drain expansion tank.

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