JPH11344203A - Method for recovering steam air heater drain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise energy utility efficiency of a plant as a whole. SOLUTION: A method for recovering a steam air heater drain has such an arrangement that boiler water blown down from a steam drum 2 is led to a flash tank 5, that flash tank drain generated in the flash tank 5 is discharged to outside, and that, on the other hand, the steam air heater drain generated by a steam air heater 3 is supplied to a low pressure feed water heater 4. The drain energy of the flash tank 5 is applied to the drain of the steam air heater 3 through a recovery turbine 13 and a pressure rising pump 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering a steam-type air preheater drain, and more particularly, to a method for guiding boiler water blown down from a steam drum to a flash tank.
A steam type air preheater drain configured to discharge a flash tank drain generated by the flash tank to the outside, while supplying a steam type air preheater drain generated by the steam type air preheater to a low pressure feed water heater. The collection method of

[0002]

2. Description of the Related Art FIG. 2 shows a system configuration of a conventional thermal power plant having a system in which blown-down boiler water flows and a system in which a steam-type air preheater drain flows. In this thermal power plant, since the impurities in the boiler water circulating in the boiler 1 are concentrated with time, the blowdown from the steam drum 2 is continuously performed in order to keep the water quality of the boiler water below a certain reference value. Part of the boiler water is discharged to the outside. The energy held by the boiler water blown down from the steam drum 2 is mainly recovered as steam by a deaerator or the like (not shown). On the other hand, the steam type air preheater drain generated by the steam type air preheater (abbreviated as SAH in FIG. 2) 3 for heating the combustion air is supplied to the low pressure feed water heater 4 and then condensed. The water is mixed and supplied to the boiler 1 again.

[0003] The blow-down system of the thermal power plant will be described in more detail. The blow-down boiler water is led to a flash tank 5 and separated by the flash tank. The vapor generated in the flash tank 5 is led to a deaerator or the like, and the liquid generated in the flash tank (hereinafter, referred to as flash tank drain).
Is guided to the blow-down tank 6 opened to the atmosphere, where it is again subjected to steam separation under the atmospheric pressure. Blowdown tank 6
The steam generated in is blown to the atmosphere, and the drain generated in the blow-down tank is cooled to outside by water or the like and then discharged to the outside. In FIG. 2, reference numeral 7 denotes a steam-type air preheater drain tank (in FIG. 2, a SAH drain tank) for temporarily storing the steam-type air preheater drain before supplying it to the low-pressure feedwater heater 4. Abbreviated).

[0004]

However, in some conventional thermal power plants, the steam-type air preheater drain is reduced in pressure depending on the operating pressure of the steam-type air preheater 3 and the arrangement of the low-pressure feedwater heater 4. In some cases, a state where supply to the feed water heater 4 could not be performed occurred. For this reason, a pump (not shown) for increasing the pressure of the steam-type air preheater drain to a pressure sufficient to flow into the low-pressure feedwater heater 4 is provided. However, when such a pump is provided, it is necessary to separately supply electric energy from the outside to a motor for driving the pump.

On the other hand, usable energy remains in the boiler water to be blown down, but this energy is not fully utilized at present, and the energy utilization efficiency of the entire plant is still improved. Room remains. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of recovering a steam-type air preheater drain that can increase the energy use efficiency of the entire plant.

[0006]

According to the present invention, in order to achieve the above object, boiler water blown down from a steam drum is guided to a flash tank, and a flash tank drain generated by the flash tank is discharged to the outside. On the other hand, in a method for recovering a steam-type air preheater drain in which a steam-type air preheater drain generated by a steam-type air preheater is supplied to a low-pressure feedwater heater, the energy of the flash tank drain is determined by a turbine. -The steam-type air preheater is supplied to the drain via the pump means, thereby eliminating the need to separately supply energy from the outside.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for recovering a steam-type air preheater drain according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a method for recovering a steam-type air preheater drain according to the present invention. Specifically, FIG. 1 shows a system configuration of a thermal power plant having a blowdown system and a steam-type air preheater. is there. Note that, for convenience of description, in the same figure, components having the same functions as those shown in FIG. 2 are denoted by the same reference numerals.

[0008] The thermal power plant of this embodiment comprises a system in which blown-down boiler water flows and a system in which a steam-type air preheater drain flows. The system side of the thermal power plant through which the blown-down boiler water flows detects the flash tank 5 into which the boiler water blown down from the steam drum 2 juxtaposed to the boiler 1 flows, and the pressure in the flash tank. A pressure detector 11, a control valve 12 provided in the middle of a piping line in which steam generated by the steam separation in the flash tank is supplied to a deaerator and the like, and a steam generated by the steam separation in the flash tank. A blow-down tank 6 to which the liquid (hereinafter referred to as a flash tank drain) is supplied, and a flash tank 5
And a recovery turbine 13 interposed in the middle of a piping line that communicates with the blowdown tank 6.

A steam type air preheater (FIG. 1) for heating the combustion air is provided on the system side through which the steam type air preheater drain flows.
Is abbreviated as SAH. 3) a steam-type air preheater drain tank (in FIG. 1, abbreviated as SAH drain tank) 7 in which the steam-type air preheater drain is temporarily stored; A low-pressure feed water heater 4 disposed downstream is installed in the middle of a piping line that connects the steam-type air preheater drain tank 7 and the low-pressure feed water heater 4, and is connected to the recovery turbine 13 by a single shaft. And a step-up pump 14.

In the thermal power plant according to the present embodiment, when boiler water is blown down from the steam drum 2, the flash tank drain generated in the flash tank 5 gives energy to the recovery turbine 13 to drive the booster pump 14. . At this time, the pressure in the flash tank 5 is monitored by the pressure detector 11, and the control valve 12 is appropriately controlled based on the obtained pressure signal. By this control, the pressure in the flash tank 5 and, consequently, the energy held by the flash tank drain are appropriately adjusted. Is controlled to have sufficient energy to be pumped to the low pressure feedwater heater 4. Then, the flash tank drain that drives the recovery turbine 13 flows into the blowdown tank 6, where it is separated by steam again at atmospheric pressure. The steam generated in the blowdown tank 6 is released to the atmosphere, and the drain generated in the blowdown tank is discharged to the outside.

On the other hand, the steam-type air preheater drain accumulated in the steam-type air preheater drain tank 7 is supplied to the low-pressure feedwater heater 4 while being sufficiently pressurized by the booster pump 14. Thus, the steam-type air preheater drain can be pressure-fed to the low-pressure feedwater heater 4 without separately supplying energy from the outside, so that the energy use efficiency of the entire plant can be improved. As in a conventional plant, when the control valve as in the present embodiment is not installed in a piping line leading from the flash tank 5 to the deaerator, the pressure in the flash tank 5 follows the load of the plant. Fluctuate. On the other hand, when the pressure detector 11 and the control valve 12 are provided in this piping line as in the present embodiment, the pressure in the flash tank 5 is adjusted to an appropriate level regardless of the plant load. Since it can be maintained, the recovery turbine 13 and the booster pump 1
4 can always maintain sufficient energy. As a result, the steam-type air preheater drain can always be satisfactorily pumped to the low-pressure feedwater heater 4, and the energy held by the blown-down boiler water can be effectively used.

[0012]

As described above, according to the method for recovering the steam type air preheater drain according to the present invention, the boiler water blown down from the steam drum is led to the flash tank, and the flash generated by the flash tank The method for recovering a steam-type air preheater drain, wherein the tank-type drain is discharged to the outside, and the steam-type air preheater drain generated by the steam-type air preheater is supplied to a low-pressure feedwater heater. The energy of the tank drain is supplied to the steam type air preheater drain via the turbine pump means, so that it is not necessary to separately supply energy from the outside. That is, in the present invention,
Since the steam-type air preheater drain is pumped to the low-pressure feedwater heater, the energy of the flash tank drain can be effectively used, so that the energy use efficiency of the entire plant can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a method for recovering a steam-type air preheater drain according to the present invention.

FIG. 2 is a diagram showing a system configuration of a conventional thermal power plant having a system through which blown-down boiler water flows and a system through which a steam-type air preheater drain flows.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 boiler 2 steam drum 3 steam-type air preheater 4 low-pressure feedwater heater 5 flash tank 6 blowdown tank 7 steam-type air preheater drain tank 11 pressure detector 12 control valve 13 recovery turbine 14 booster pump

Claims (1)

[Claims] 1. Boiler water blown down from a steam drum is led to a flash tank, and a flash tank drain generated by the flash tank is discharged to the outside.
On the other hand, in a method of recovering a steam-type air preheater drain in which the steam-type air preheater drain generated by the steam-type air preheater is supplied to a low-pressure feedwater heater, the energy of the flash tank drain is transferred to a turbine A method for recovering the steam-type air preheater drain, which is provided to the steam-type air preheater drain via a pump means.