JP3587895B2 - Economizer - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an economizer for preheating water supplied to a boiler with combustion exhaust gas of a boiler.
[0002]
[Prior art]
2. Description of the Related Art Economizers that preheat water supplied to a boiler with the heat of combustion exhaust gas discarded from the boiler are widely used to effectively use the heat. The structure of a normal economizer is to provide a water pipe so as to penetrate the flue, and to install a U-shaped tube outside the flue or a mirror plate outside the flue and connect it to the part covered with the mirror plate to turn the path The path is lengthened by repeatedly piercing the flue in the opposite direction again, and the water pipe in the flue is provided with a large number of fins to improve heat absorption. In this case, the water pipe and the body are fixed by welding in order to prevent the flue gas from leaking from the gap between the water pipe and the flue wall. However, when flue gas is passed into the flue, there is a difference in thermal expansion between the water pipe cooled by water flow and the uncooled flue, and the body or water pipe is damaged during repeated heating and cooling over a long period of time Things were happening.
[0003]
Therefore, as described in Japanese Utility Model Application No. Hei 5-30551, the body and the water pipe are fixed on only one side so that the body and the water pipe can be expanded and contracted separately, and the other end does not fix the body and the water pipe, and the combustion exhaust gas leaks. In order to prevent this, a cover is provided to cover the surface not fixed. With such a structure, damage to the body or the water pipe due to the difference in expansion could be eliminated, but it would be necessary to attach a cover that had not been provided before. On the other hand, even if one side of the welded part of the water pipe is folded inside the flue so that it does not come out of the flue, the force due to the difference in expansion is not applied, but in this case, the flue gas is not bent at the bent part without fins , The efficiency of heat recovery is reduced.
[0004]
The heat discarded from the boiler other than the combustion exhaust gas includes heat discarded in the boiler blow water. In order to use heat effectively, it is necessary to recover heat from blow water. Further, since the blow water is alkaline, it is necessary to perform a neutralization treatment before draining.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to eliminate damage to a body or a water pipe due to a difference in thermal expansion, and to provide an economizer that can perform heat recovery from blow water and neutralize blow water. is there.
[0006]
[Means for Solving the Problems]
In the economizer installed in the flue through which the flue gas generated by the boiler flows, a large number of vertical water pipes are arranged in the flue by folding the water supply path at the upper and lower parts of the flue, and at least the lower folded part is inside the flue. And a spray nozzle for injecting blow water from the boiler is provided toward the water pipe in the flue, and the blow water is sprayed toward the water pipe, and provided at the lower part of the flue so that the folded part is immersed in water. Collect blow water in the water tank.
[0007]
[Action]
By storing water in the folded part of the water pipe at the lower part of the flue, it is possible to prevent the flue gas from passing through the folded part, so there is no need for a special structure to prevent short paths, and the equipment can be simplified. And the water supply can be preheated by making full use of the heat of the combustion exhaust gas. Further, the water pipe portion in the high-temperature blow water can absorb the heat of the blow water. Furthermore, by injecting the alkaline blow water into the combustion exhaust gas, it is neutralized by contact with the acidic carbon dioxide gas or nitrogen oxide contained in the exhaust gas, and the PH of the waste water can be controlled. .
[0008]
【Example】
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an outline of the economizer portion. A water supply pipe for supplying water to the boiler (1) is connected to an economizer provided in a flue section (2) of the boiler, and is preheated by combustion exhaust gas. The economizer is formed by a fin tube (3) provided vertically in the flue, a U-shaped tube (4) in the lower part of the flue, and a head plate (5) on the upper surface of the flue, and a water supply pipe which enters vertically into the flue. Is repeatedly folded back by a U-shaped tube connected at the lower part in the flue, connected to the inside of the end plate provided on the upper surface of the flue, and folded back again. Blow water discharged from the boiler and passed through the blow pipe (6) is sprayed toward a fin pipe (3) from a spray nozzle (7) provided in the flue, and a drain pipe provided in a lower part of the flue. Since (8) is located higher than the U-shaped pipe, the blown water that has been injected is stored in the lower part of the flue.
[0009]
The flue gas sent from the boiler (1) flows laterally in the economizer section, and all the flue gas flows across the fin tube due to the accumulation of water in the lower part of the flue. The fin tube is heated when crossing the tube (3). The connecting part between the U-shaped pipe (4) and the fin pipe (3) is in the water part (9) stored in the lower part of the flue, and even if there is a hole in the connecting part, there is water around and there is leakage. It becomes difficult. When the alkaline blow water is injected into the flue, it is neutralized by the combustion exhaust gas flowing in the flue, and the neutralized water is drained from the drain pipe (8). In addition, since the blow water has a high temperature, the injection of the blow water can also perform the preheating of the feed water by the heat held by the blow water, and the heat is effectively used and the blow water is neutralized. .
[0010]
【The invention's effect】
By implementing the present invention, the following effects can be obtained. Even though the economizer has a simple structure, the flue gas can be reliably used for preheating the feedwater without causing a short path, so that the heat recovery rate is improved. Even if a hole is formed in the connecting portion between the U-shaped tube and the fin tube in the flue, it is hard to leak because it is sealed with water. The blow water can be neutralized by the combustion exhaust gas, and the neutralized water can be drained. The heat held by the blow water can be used effectively.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of one embodiment of the present invention.
REFERENCE SIGNS LIST 1 boiler 2 flue section 3 fin pipe 4 U-shaped pipe 5 head plate 6 blow pipe 7 spray nozzle 8 drain pipe 9 water

Claims (2)

In the economizer installed in the flue through which the flue gas generated by the boiler passes, a large number of vertical water pipes are arranged in the flue by folding the water supply path at the top and bottom of the flue, and at least the lower folded part is inside the flue. The economizer is provided with a water tank in the lower part of the flue so that the folded part at the bottom is immersed in water. The economizer according to claim 1, wherein a spray nozzle for spraying blow water from the boiler is provided in the flue, and the blow water sprayed from the spray nozzle is collected in a water tank below the flue.

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