JPH05126315A - Method of water supply and water drainage of deaerator in waste heat recovery boiler and device thereof - Google Patents

Abstract

PURPOSE:To utilize the heat source efficiently by changing the blow water discharged from an deaerator into thickened water through the treatments of pressure reduction, evaporation, and heat exchanging and supplying to the deaerator the supply water which is a mixture of the condensed water and soft water. CONSTITUTION:To a blow water discharge device a steam generating and pressure reduction chamber 21 is added, and this steam generating and pressure reduction chamber 21 and a supply water tank 3 are connected by providing a steam pipe 22, condenser 23, and condensed water tube 24 and, at the same time, a supply water pipe 10 of the supply water tank 3 is made to penetrate the condenser 23 and it is connected to a deaerator 4. And, the pressure of the blow water that is discharged from the deaerator 4 is reduced in the pressure reduction chamber 21, and part of the blow water is evaporated in the evaporation pipe 22, and that steam exchanges heat with the supply water indirectly in the condenser 23 to become condensed water. The supply water which is the mixture of this condensed water and soft water is supplied by circulation to the deaerator 4 through the supply water tank 3. With this arrangement there is no increase in the supply water, and it is possible to utilize the heat source effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying and draining a waste heat recovery boiler deaerator and a device therefor.

[0002]

2. Description of the Related Art Waste heat recovery boilers are often used in steelworks and the like to recover the sensible heat of high temperature waste gas. For example, a coke dry-type fire extinguisher installed near a coke oven is equipped with a waste heat recovery boiler to cool red hot coke with a gas such as nitrogen, and to heat water with those high temperature waste gases heated by heat exchange. Heat is generated by generating steam to recover heat.

Generally, a waste heat recovery boiler is equipped with a deaerator,
Therefore, steam-water separation is performed, the generated steam is further heated in the boiler, taken out of the system as superheated steam, while the generated high-temperature water is further heated in the boiler to generate steam,
It is circulated to the deaerator and used as its heating source.

Water supply to the deaerator is performed in a preheated state, and various proposals have been made as a means for preheating the water supply in order to effectively utilize a series of heating sources. As an example, there is a feed water heating device as shown in Japanese Utility Model Laid-Open No. 1-177253.

As shown in FIG. 4, the coke chamber 1
A waste heat boiler 2 provided with a deaerator 4 is provided adjacent to. Here, boiler water tank 3 to deaerator 4
Between the water-to-water heat exchanger 6 for exchanging heat between the water supply to the indirect heat exchanger 5 and the hot water on the outlet side of the indirect heat exchanger 5, and the indirect heat exchanger 5 7, a circulation pump 8 is provided to form a circulation water passage, and a return steam pipe 9 is provided between the steam separator 7 and the deaerator 4, which is a heating device for water supply of coke dry fire extinguishing equipment. .. According to this, since dewatered feed water is introduced and circulated between the indirect heat exchanger 5 and the water-to-water heat exchanger 8, there is almost no dissolved oxygen, so there is no corrosion due to it. ..

As another example, Japanese Utility Model Laid-Open No. 63-10744 discloses a device for preheating the feed water of a heat recovery boiler of a coke dry fire extinguisher before deaeration, in which a circulating gas distribution chamber under a cooling tower is preheated. There is described a boiler feed water preheating device in which an indirect heat exchange pipe is installed, and a boiler feed water inlet side of the indirect heat exchange pipe is connected to a pure water tank and an outlet side is connected to a deaerator.

Further, Japanese Utility Model Publication No. 63-78046 discloses that
An indirect heat exchanger is connected to the lower part of the powder coke hopper of the primary dust remover installed in the flue that guides the circulating high-temperature gas to the heat recovery boiler in the device that preheats the feed water of the heat recovery boiler of the coke dry fire extinguisher However, there is described a boiler feedwater preheating device in which a boiler feedwater inlet side of the indirect heat exchanger and a feedwater tank, and an outlet side of the indirect heat exchanger are connected to a deaerator.

On the other hand, although the waste heat recovery boiler deaerator described above is not particularly described, in this type of deaerator, blow water is intermittently or continuously withdrawn, and the blow water passes through a blow tank. , Processed by thickener.

[0009]

In the waste heat recovery boiler deaerator as described above, it is important to control the water used for it. The water used for this type of waste heat recovery boiler deaerator is treated inside and outside the boiler. Outside the boiler, in order to remove impurities dissolved in water, a softening treatment is performed with an ion exchange resin or the like, and so-called soft water is used as water supply.

Soft water is water containing very few carbonates (primary hardness) and non-carbonates (permanent hardness). In Japan, the hardness is 90 ppm or less. Chemicals such as phosphates are added as detergents in the boiler. Generally, both processes are performed.

However, even if such treated soft water is used as the feed water, it is concentrated during the vaporization of the soft water to generate steam, which causes scale and sludge to have an adverse effect. Therefore, in the deaerator, the blow water is drained intermittently or continuously. In this case, the amount of total evaporation residue (dissolved fixed amount) contained in the boiler water (mg / l)
And the electrical conductivity (μS / cm) are almost proportional to each other.

Therefore, as one of the control items for water supply and boiler water, the electric conductivity (μS / cm) is mentioned in addition to pH. The soft water used as water supply is water-treated, but depending on the treatment, electric conductivity (μS
/ Cm) is as high as about 200 μS / cm, so that the boiler water is rapidly concentrated due to this, and the amount of blow water to be removed increases.

Generally, for safety, electrical conductivity (μS /
(cm) is based on 2000 μS / cm, and blow water is drained and discharged. When the amount of blow water removed increases, the steam generation rate deteriorates, the steam generation unit decreases, and the supply water increases, which is a problem. In addition, there is a problem that heat loss increases due to blow water.

Although various types of heat sources have been effectively used in the above-mentioned conventional feed water heating apparatus for the waste heat recovery boiler deaerator, the above problems caused by the increase in the amount of blow water extracted are not touched at all. Has not been done.

The present invention is intended to solve the above-mentioned problems. Even if soft water is used for supplying water to the waste heat recovery boiler deaerator, the amount of blow water to be treated is small and the amount of water supply increases. It is an object of the present invention to provide a water supply / drainage method for a deaerator of a heat recovery boiler and a device therefor capable of effectively utilizing a heat source without generating heat.

[0016]

In order to achieve the above object, the present invention supplies soft water to a deaerator of a waste heat recovery boiler and discharges blow water from the deaerator. Depressurizes the blow water to evaporate part of it,
A method of supplying and draining a waste heat recovery boiler deaerator, characterized in that the steam is indirectly heat-exchanged with feed water to form condensed water, and the condensed water is mixed with soft water to supply the deaerator. It is what

The present invention also provides a water supply device connected to a deaerator of a waste heat recovery boiler and a blow water discharge device as a supply device suitable for carrying out the above method. A steam generation decompression chamber is attached to the steam generation decompression chamber, and the water supply tank of the water supply device is connected by disposing a steam pipe, a condenser, and a condensed water pipe, and the water supply tank of the water supply tank is connected to a condenser. The water supply / drainage device of a waste heat recovery boiler deaerator is characterized in that it is penetrated and connected to a deaerator.

FIG. 2 shows the relationship between the temperature of blow water and the recovery rate of blow water by decompression according to the method of the present invention. The temperature of the blow water due to the reduced pressure can be appropriately selected.

In the present invention, since the feed water in which the condensed water of steam is mixed with the soft water is supplied to the deaerator of the waste heat recovery boiler, the electric conductivity of the feed water is lower than that of the plain water alone, and a part of the blow water is used. Can be restored to the water supply, and the steam in the steam generation decompression chamber is used as the heat source for raising the temperature of the water supply, so that the heat can be effectively used.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. Here, the water supply / drainage device applied to the deaerator of the waste heat recovery boiler of the coke dry fire extinguishing equipment will be described. In the figure, 21 is a steam generation decompression chamber, 22 is a steam pipe, 23 is a condenser, and 24 is a condensation pipe.

The deaerator water supply / drainage device of the present invention is a water supply device connected to a deaerator 4 of a waste heat recovery boiler 2 installed near a coke chamber (not shown), and a blow water discharge device. Then, a steam generation decompression chamber 21 is attached to the blow water discharge device, and the steam generation decompression chamber 21 and the water supply tank 3 of the water supply device are connected to a steam pipe 22, a condenser 23,
A condensate water pipe 24 is provided and connected, and the water supply pipe 10 of the water supply tank 3 is connected to the deaerator 4 through the condenser 23.

In the waste heat recovery boiler 2, the steam generated in the deaerator 4 is further heated and sent as superheated steam 11 to the outside of the system. The high-temperature water generated in the degasser 4 is heated by the waste heat recovery boiler 2 to become steam 12, which is circulated to the deaerator 4 and used as a heating source. Blow water is discharged intermittently or continuously from the deaerator 4, and a part of it is cooled by a sample branch pipe 28 equipped with a cooler 29, and then the electrical conductivity, pH and the like are measured.

The blow water is heat-exchanged with the feed water in the cooler 27 to lower the temperature to about 100 ° C., and then sent to the steam generation decompression chamber 21. The vapor generation decompression chamber 21 is decompressed by the ejector 26. The blow water that has generated steam in the steam generation decompression chamber 21 is processed by a thickener via a blow tank 25. The arrow in the figure indicates the direction.

The water supply / drainage device as described above is applied to a deaerator of a waste heat recovery boiler of a coke dry fire extinguisher system to supply soft water to the deaerator and to discharge blow water, from the deaerator. The discharged blow water is decompressed, a part of it is evaporated, the steam is indirectly heat-exchanged with the feed water to form condensed water, and the condensed water is mixed with soft water to supply water to the deaerator. Supply.

According to the method of the present invention, as shown in FIG. 3, the blow rate can be improved by changing the feed rate of soft water by the condensed water. As is clear from the figure,
The blow rate is improved by lowering the soft water supply rate, but practically 0.3-
A pressure of about 0.6 atm is used.

According to the method of the present invention, when the blending ratio of soft water is adjusted to about 60% to make water supply, the amount of blow water is larger than that of conventional blow water. It could be reduced to about 2/3.

[0027]

As described above, according to the present invention, even if soft water is used for supplying water to the waste heat recovery boiler deaerator, the amount of blow water to be treated is small, and the increase in water supply does not occur. It can be used.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between the temperature of blow water and the recovery rate of blow water according to the present invention.

FIG. 3 is a diagram showing an example of the amount of Plow water with time of the deaerator of the present invention.

FIG. 4 is a diagram showing an example of a feed water heating apparatus for a deaerator of a conventional waste heat recovery boiler.

[Explanation of symbols]

 1 Coke Chamber 2 Waste Heat Boiler 3 Boiler Water Supply Tank 4 Deaerator 5 Indirect Heat Exchanger 6 Water-to-Water Heat Exchanger 7 Water-Water Separator 8 Circulation Pump 9 Return Steam Pipe 10 Water Supply Pipe 11 Superheated Steam 12 Steam 21 Steam Generation decompression chamber 22 Steam pipe 23 Condenser 24 Condensed water pipe 25 Blow tank 26 Ejector 27 Cooler 28 Sample branch pipe 29 Cooler

Claims (2)

[Claims] 1. When soft water is supplied to a deaerator of a waste heat recovery boiler and blow water is discharged, the blow water discharged from the deaerator is decompressed and a part thereof is evaporated, and its steam is discharged. A method for supplying and draining waste heat recovery boiler deaerator, characterized in that the water is indirectly exchanged with the water supply to form condensed water, and the condensed water is mixed with soft water and the supplied water is supplied to the deaerator. 2. A water supply device connected to a deaerator of a waste heat recovery boiler, and a blow water discharge device, wherein the blow water discharge device is additionally provided with a steam generating pressure reducing chamber. And a water supply tank of the water supply device is arranged to connect by connecting a steam pipe, a condenser and a condensed water pipe, and the water supply pipe of the water supply tank is connected to a deaerator by penetrating the condenser. A water supply and drainage device for a waste heat recovery boiler deaerator.