JPH02233107A - Degassing method at starting time of steam power plant - Google Patents

Abstract

PURPOSE:To shorten the starting time of cleanup, in cleaning up the recirculation system of a steam power plant with recirculation water, by introducing the steam generated from a steam separator into the water storage tank of a deaerator and heating the recirculation water by said steam to deaerate the same under vacuum. CONSTITUTION:When the recirculation system of a steam power plant is cleaned up with recirculation water, the steam generated from a steam separator 19 is introduced into the water storage tank 11 of a deaerator 11 and the recirculation water is heated by said steam to be deaerated under vacuum. That is, the steam controlled in its pressure by a pressure control valve 34 is guided to the water storage tank 11 of the deaerator from the upper part of the steam separator 19 by a pipeline 33 to heat the recirculation water in the water storage tank 11. As mentioned above, a system sufficiently obtaining the amount of steam necessary for heating the recirculation water from a boiler system is constituted and the cleanup of both of a system of a high pressure water supply heater 14 and a system of a boiler 16 is effectively performed by increasing the flow rate of the recirculation water. As a result, the starting time of cleanup can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a degassing method for reducing dissolved oxygen in circulating water during a clean-up operation K at startup of a thermal power plant.

[Conventional technology]

An example of the cleanup system of a conventional thermal power plant is shown in Figure 2K.

In Fig. 2k, 1 is a condenser, above which a turbine 2 is installed, and below K a hot well 3 is installed. Further, 4 is a group of tubes through which cooling water for cooling the steam exhausted from the turbine 2 passes. One end of a conduit 5 is connected to the bottom K of the hot well 3, and a condensate pump 6, a desalination device 7,
A condensate boost pump 8 and a low-pressure feed water heater 9 are arranged, and the other end of the pipe is connected to the inlet of a deaerator 10. Deaerator 10
A deaerator water tank 11 is connected to the lower part K of the deaerator. One end of a water supply pipe 12 is connected to the bottom of the deaerator water tank 11, and the water supply pipe 12K is equipped with a water pump 13, a high pressure water heater 14, and a high pressure water heater outlet valve l5. The other end of the pipe is connected to boiler l6. A brackish water separator 19 is installed on the outlet side of the boiler l6 in a pipe line 18k, and the steam outlet of the brackish water separator 19 is connected to a superheater 17k. IJ, The following piping system is provided for the purpose of cleaning up the above-mentioned equipment and piping at the time of plant start-up. That is, it has a valve, and one end is a sharp air tank 11k,
The other side is the condenser 1k, each connected to a low pressure cleanup pipe 21, one end is branched from between the high pressure feed water heater 14 and the valve 15 on its outlet side, and the other end is connected to the condenser via the valve n. preboiler clean-up pipe n, and one end connected to the brackish water separator 19k. The other end is connected to the condenser l, respectively, and has a boiler clean-up pipe 5
, 03 lines are provided. In addition, for the purpose of deaeration of dissolved oxygen in the circulating water, a vacuum pump is applied to the condenser IK, and an auxiliary steam pipe 4 connected to the auxiliary boiler 28K is degassed via valve n to the sharp air storage tank l1. Air vent pipes 31 connected to the condenser 1 via valves are installed in each of the containers 10K.

In the above configuration K, a conventional cleanup method for the low pressure preboiler system, high pressure boiler system, and boiler system K of the thermal power plant will be explained.

First, in the low-pressure preboiler system, the vacuum is raised by a vacuum pump connected to the condenser 1, and the condensate pump 6, desalination device 7, condensate boost pump 8, Low-pressure feed water heater 9, deaerator 10, deaeration water tank 1
1 and returns to the condenser 1 via a low-pressure clean-up pipe 21, a system K circulates pure water to clean the inside of the system.

Next, in the high-pressure preboiler system, using the purified water stored in the deaerator water tank 11K, it is returned to the condenser 1 through the water supply pipe 12, the water supply pump 13, the high-pressure feed water heater 14, and the preboiler cleanup pipe. Clean up the system by circulating pure water through the system.

After that, clean the boiler system. That is boiler 1
6Vc water is passed through, and the pure water is circulated through the steam water separator 19 and back to the condenser IVc through the boiler cleanup pipe 5.
Boiler cleanup will be carried out. This boiler clean-up consists of a boiler cold clean-up in which pure water 16K stored in the deaerator water tank 11 is passed through the boiler l6 to purify the boiler l6, and a boiler cold clean-up in which boiler l6 is ignited and circulated water is ignited at the boiler outlet. Temperature 120~170℃ 1fKL
This process consists of two steps: boiler hot cleanup.

This circulating water is vacuum degassed in the condenser 1 to remove dissolved hydrogen to 0. The condenser 1 and the deaerator 10 are connected to each other. The vacuum in the deaerator 10 and the deaerator water tank 11 is maintained by the air vent pipe 31, and heating vacuum deaeration is performed within the container to reduce dissolved oxygen in the circulating water to 0.01 ppm or less. Further, the circulating water is purified by a desalination device 7.

[Problem to be solved by the invention]

The above conventional cleanup method traps have the following drawbacks.

In other words, the clean-up operation that is carried out at startup of a thermal power plant removes iron rust and mud within the system. Therefore, in order to quickly remove iron rust in the system and prevent iron from leaching from equipment and piping made of steel, it is effective to clean up with sufficiently degassed high-temperature water. be.

However, in the conventional method, in order to degas the dissolved oxygen in the circulating water to the target level of 0.01 ppm or less in the deaerator water tank 11, vacuum deaeration is performed and the temperature of the K circulating water is It was necessary to heat it up even more. In order to heat a large amount of circulating water in the deaerator water tank 11, it becomes necessary to install a large-capacity auxiliary boiler as a heating steam source, which significantly increases equipment costs. Here, it is conceivable to reduce the circulation flow rate of the circulating water or to temporarily stop the system circulation and take measures to obtain hot water in the water tank 11. However, effective cleanup requires the use of large flows of degassed water. If the cleanup is performed at a small flow rate, the cleanup operation will take a long time and the plant start-up time will be long.

Furthermore, thermal power plants in recent years are less likely to operate continuously as in the past, and tend to be shut down and started on weekends or started and stopped every day depending on the power supply situation. Under such operating conditions, when restarting a stopped plant, the dissolved oxygen in the circulating water is reduced as quickly as possible in the deaerator and deaerator water tank to complete plant cleanup. There is a need to. However, with the above conventional method, it is difficult to shorten the startup time.

[Means to solve the problem]

In order to solve the above-mentioned conventional problems, the present invention provides a method for cleaning up the circulation system of a thermal power plant using circulating water.
This paper proposes a degassing method at the time of startup of a thermal power plant, which is characterized in that steam generated from a brackish water separator is introduced into a deaerator storage tank K, and circulating water is heated by the steam and vacuum degassed.

[For production]

The present invention utilizes boiler-generated steam as a heating steam source for heating and vacuum degassing carried out in a deaerator storage tank, thereby effectively performing cleanup at the time of startup of a thermal power plant and reducing equipment costs. It's something. That is, in the present invention, generated steam is introduced into the steam storage tank K from the steam system of the steam separator installed on the boiler outlet side, and the circulating water for cleanup is heated to ω°C or higher and then heated and vacuumed. Evangelism will be carried out and effective clean-up will be carried out.

〔Example〕

FIG. 1 is a cleanup system diagram showing one embodiment of the present invention. In FIG. 1K, the same parts as in FIG. 2 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this example, a conduit plan is added to the conventional system. One end of this pipe is connected to the steam side K of the brackish water separator 19, and the other end is connected to the deaerator water tank 1 via a pressure control valve A.
It is connected to auxiliary steam pipe 4 which is connected to 1.

The pressure regulating valve A is controlled by a temperature sensor (not shown) provided in the deaerator water tank 11K.

In the above configuration, the condenser 1, the condensate pump 6, the desalination device R7, the boost pump 8, the low pressure feed water heater 9, the deaerator 10,
After completion of the low pressure cleanup, which is returned to the condenser 1 through the deaerator water tank 11 and the low pressure cleanup pipe 21,
Valve the generated steam in the auxiliary boiler! The circulating water is introduced into the deaerator water tank 11 through the auxiliary steam pipe 4 while adjusting the temperature, and the circulating water is heated and vacuum degassed. If it is not possible to maintain the circulating water temperature above ω℃, try to maintain the temperature by reducing the circulating water flow rate.

When the dissolved oxygen in the deaerator water tank 11 becomes 0.01 ppm or less, the water supply pump 13 is started, and the deaerated water in the deaerator water tank 11 is sent to the high-pressure feed water heater 14 via the water supply pipe l2.
, water is passed through the pot 16. In this case, the circulating water route includes a circulation system in which the water is returned to the condenser 1 through a preboiler cleanup pipe n branched from the outlet side of the high-pressure feed water heater 14, and a circulation system that flows through the boiler 6, the pipe line 18, and the brackish water separator. There is a circulation system in which the water is returned to the condenser 1 via the boiler clean-up pipe 5 via the boiler clean-up pipe 5. The flow rate of both systems is determined by the high pressure feed water heater outlet valve I5.
, valve η, is adjusted by discrimination. After securing the minimum flow rate that can ignite the burner in the boiler 6 system, ignite it and
The temperature is raised and maintained until the outlet fluid temperature reaches about 10 degrees. The hot water introduced into the brackish water separator 19 through the pipe 18'''!! is returned to the condenser IK from the lower part (liquid side) of the brackish water separator 19 through the valve rotor through the boiler cleanup pipe δ and then returns to the boiler. Perform a system cleanup.

In this embodiment, the steam water is guided from the upper part (steam side) of the steam separator 19 to the steam deaerator water tank 11 regulated by the pressure regulating valve through a pipe, and the circulating water in the steam water tank 11 is Warm up. In this way, once a system that can obtain a sufficient amount of steam necessary for heating circulating water from the boiler system is configured, the circulating water flow rate is increased and the 14 high-pressure feedwater heater systems and boiler l
Effectively implement cleanup of 6 systems. The amount of steam introduced into the deaerator water storage tank 11K is controlled by the pressure control valve U, but if it is possible to raise and maintain the temperature of the circulating water with this steam, close the valve n of the auxiliary boiler system. Stop introducing steam from auxiliary steam pipe 4.

〔Effect of the invention〕

The present invention K provides the following effects.

(11 By using the steam generated by the foiler,
The deaerator water tank makes it possible to degas the large volume of circulating water required for cleanup, making cleanup more effective and reducing start-up time.

(2) The generated steam capacity of the auxiliary boiler is reduced, making it possible to reduce equipment costs.

[Brief explanation of the drawing]

FIG. 1 is a cleanup system diagram showing an embodiment of the present invention, and FIG. 2 is a system diagram showing an example of a conventional cleanup system of a thermal power plant. 1... Condenser; 2... Turbine; 3...
・Hot well: 4... Cooling water pipe group; 6... Condensate pump; 7... Desalination device; 8... Condensate boost pump; 9... Low pressure feed water heater; 10... Deaerator; 11
... Deaerator water tank; 12 ... Water supply pipe; 13 ... Water supply pump; 14 ... High pressure feed water heater; l5 ... High pressure feed water heater outlet valve; l6 ... Boiler; 17 ... Superheater; 19... Brackish water separator; 21... Low pressure cleanup pipe; B... Preboiler cleanup pipe; 5... Boiler cleanup pipe; G... Vacuum pump; ...Auxiliary boiler; 4...
・Auxiliary steam pipe; 31...Air vent pipe; 32...Burner; San...Pressure control valve. Two patent attorneys represented by Akigai Sakama

Claims (1)

[Claims] When cleaning up the circulation system of a thermal power plant with circulating water, the steam generated by the brackish water separator is introduced into the deaerator storage tank, and the circulating water is heated by the steam and vacuum degassed. Degassing method when starting up a thermal power plant.