JPS59115902A - Heavy-oil combustion boiler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiler body provided with a feed water preheater in the flue.

In conventional boiler bodies of this type, the temperature of the combustion gas passing through the feedwater preheater is relatively high (e.g. 230-300"C) to avoid low-temperature corrosion problems to the feedwater preheater.
The heat loss released by the exhaust gas was large. In other words, conventionally used feed water preheaters are generally made of boiler steel material (for example, STB material), so the exhaust gas temperature can be adjusted to, for example, /30 to 2.
When the temperature drops to about 0.00"C, sulfuric acid is generated from the sulfur dioxide gas contained in the exhaust gas, and the generated sulfuric acid adheres to the outer surface of the feed water preheater, corroding the feed water preheater in a relatively short period of time, and causing damage to the water preheater. However, in conventional heavy oil-fired boilers, the temperature of the exhaust gas passing through the flue was maintained at a relatively high temperature range without the risk of low-temperature corrosion. This resulted in increased heat loss as described above.

Note that it is desirable to keep the temperature of the exhaust gas released into the atmosphere as low as possible in terms of thermal efficiency, but if the temperature of the exhaust gas is lowered to, for example, about 10°C, the moisture in the exhaust gas that comes into contact with the feed water preheater will increase. The condensation water tends to form condensation, and the sulfur dioxide gas in the exhaust gas dissolves, gradually producing highly concentrated sulfuric acid. The exhaust gas temperature and the surface temperature of the feed water preheater are important factors in the formation of this concentrated sulfuric acid. The temperature of the contacting exhaust gas is /
Left 0-. 200℃, the surface temperature of the water supply preheater is 60~/
It has been found that high concentrations of sulfuric acid are actively produced under conditions that satisfy each range of 20"C. Furthermore, condensed water, which is one of the important factors for the production of sulfuric acid, is
The lower the surface temperature of the feed water preheater (for example, below 110@C), the more condensation will be generated, but low-temperature corrosion will not occur just because a large amount of condensed water is generated, and on the contrary, the generated sulfuric acid will be diluted. As a result, the progress of low-temperature corrosion is slowed down.

By the way, in the flue, the temperature of the exhaust gas decreases sequentially as it passes from the entrance to the exit of the flue, and on the other hand,
The surface temperature of the feed water preheater increases sequentially from the inlet side to the outlet side of the feed water, but each temperature range in which concentrated sulfuric acid as described above is actively generated on the surface of the feed water preheater,
That is, the exhaust gas temperature in contact with the feed water preheater is /30-200
The range in which the image condition that the temperature of the feed water preheater is 60-120° C. is satisfied can be limited to some extent depending on the boiler model, purpose of use, method of use, etc.

In view of the problems of conventional heavy oil-fired boilers and the mechanism by which concentrated sulfuric acid is produced, the present invention improves thermal efficiency by making it possible to lower the temperature of exhaust gas passing through the flue to a relatively low temperature range. The present invention has been made for the purpose of providing a heavy oil-fired boiler that can cope with the problem of low-temperature corrosion while also being able to deal with the problem of low-temperature corrosion. , the feed water preheater is configured by combining a plurality of heat exchanger parts with different sulfuric acid corrosion resistance, and the feed water subheater is constructed by combining a plurality of heat exchanger parts with high sulfuric acid corrosion resistance of the feed water preheater. The apparatus is characterized in that it is located in a location in the flue where a1m sulfuric acid is likely to be generated.

Hereinafter, the heavy oil combustion boilers of the present invention will be explained with reference to the illustrated embodiments. Figures 1 [4 to 11] show the heavy oil combustion boilers of the first to 11th embodiments of the present invention, respectively.

First, what are the common parts in the heavy oil combustion boilers of the embodiments shown in Figs. 1 to 11? To explain lj a, in each figure, the symbol / indicates the boiler body.

The inside of the casing of the boiler body and the flue 2 are communicated via an exhaust pipe 7.

Pipe joint 2/c that connects the water supply preheater and the supply 7 to the pipe t and the pipe B
t and 21b are formed in an upper and lower vertical structure, and can be connected to each of the water supply pipes t and 2 even if the water supply preheater/3 is turned upside down.

Also, this water supply preheater/3 has its population/3Φ side and outlet/
The 3b side can be separated into water supply pipes and water supply pipes B, respectively. In addition, the code|symbol j is a water supply pump.

The feed water preheater /3 has two heat exchanger parts with different sulfuric acid corrosion resistance /4! , /,t.

i/The feed water preheater/3 of the boiler of the first embodiment shown in the figure is:
Two heat exchanger parts with sulfuric acid corrosion resistance /l, /3
It is composed of separably joined together. Two heat exchanger parts of this feedwater preheater /3 /It, /! ; are formed to have the same shape. Literature Two Heat Exchanger Parts/lI,
/! The heat exchanger part/lI with higher sulfuric acid corrosion resistance is made of a sulfuric acid resistant material such as stainless steel, titanium alloy steel, lead, etc., or the sulfuric acid resistant material is attached to the outer surface of the tube. Sulfuric acid corrosion resistance is imparted by methods such as Also, the two heat exchanger parts of the feed water preheater /3 /11-, /! The heat exchanger portion 15, which is not specially provided with sulfuric acid corrosion resistance, is formed from a commonly used boiler steel material (for example, STn material). In addition, the two heat exchanger parts of the feed water preheater /3 /l, /! The sulfuric acid corrosion resistance can also be varied by varying the thickness of the tube wall.

This feed water preheater/3 is installed such that the heat exchanger part/1 part, which has high sulfuric acid corrosion resistance, is located in a place where low-temperature corrosion is likely to occur (where concentrated sulfuric acid is likely to be produced).

In other words, if the upper half of the feedwater preheater used in the boiler shown in Figure 1 is susceptible to low-temperature corrosion, the feedwater preheater/3 should be replaced with the heat exchanger with higher 1lliJ sulfuric acid corrosion resistance. It is installed with the section /Il on the top side, and conversely, if the lower half of the feed water preheater /3 is prone to low-temperature corrosion, it is installed with the heat exchanger section /I/- on the bottom side. In addition, water supply preheater/3
As mentioned above, low-temperature corrosion is most likely to occur in the feed water preheater/3, but the locations where this low-temperature corrosion is likely to occur are limited to some extent depending on the boiler model, purpose of use, method of use, etc. The location can be predicted in advance when the boiler is installed.

In each of the boilers shown in the second and third embodiments shown in FIGS. 2 and 3, the feedwater preheater/3 connects the heat exchanger section/II with higher sulfuric acid corrosion resistance to the heat exchanger section/II of the other one. exchanger part 1
It is formed slightly shorter than 5.

When supplying relatively low-temperature feed water without blow water from the inlet/3α of the feed water preheater/3, install it with the heat exchanger part/g, which is highly resistant to sulfuric acid corrosion, on the lower side, as shown in Figure 2. Conversely, as shown in Fig. 3, blow water from the boiler main body is mixed into the water supply pipe through the blow water pipe 10, and relatively high temperature water is supplied to the inlet of the water preheater/3. When doing so, the heat exchanger part with high sulfuric acid corrosion resistance/
It is installed with II facing upward.

In the boiler of the second embodiment shown in Fig. 3, the feed water preheater/3
A 7-piece undivided type is used, and a part of the water preheater/3 that is prone to low-temperature corrosion is treated to improve sulfuric acid corrosion resistance. It has a high heat exchanger part and a second part. In this example, the treatment for increasing the sulfuric acid corrosion resistance is, for example, the heat exchanger portion/l.

It is possible to use methods such as varying the thickness of the tube wall of force ゛/j, alumina processing, lead vapor deposition, etc.

Next, to explain the present invention in detail, the heavy oil combustion boiler of the present invention includes a feed water preheater/3 and a plurality of heat exchanger parts/l,/! having different sulfuric acid corrosion resistance. ; and furthermore, the heat exchanger part/l with higher sulfuric acid corrosion resistance is located in a place where low-temperature corrosion is likely to occur, so the problem of low-temperature corrosion is The residual heat recovery can be maximized by lowering the temperature to a relatively low temperature, which has the effect of greatly contributing to improving the thermal efficiency of this type of heavy oil-fired boiler.

In addition, if the water supply preheater/3 can be installed upside down as shown in the examples shown in the figure, even if there is a place with severe low-temperature corrosion conditions in either direction, the water supply can be adjusted accordingly. Heat exchanger part on the side with high sulfuric acid corrosion resistance of preheater/3/l
can be located.

[Brief explanation of drawings]

FIGS.
1 is a schematic diagram of a heavy oil combustion boiler according to an example. ／・・・・・・Boiler body／２・・・Fue duct／３・・・Water heater

Claims (1)

[Claims] / is a heavy oil combustion boiler equipped with a feed water preheater C/3) in the flue (/2), wherein the feed water preheater (/3) is equipped with multiple heat exchanger parts (C/3) having different sulfuric acid corrosion resistance. /I1./!;)
are combined to form a preheater, and the water supply preheater (/3)
The heat exchanger portion (/l) with high sulfuric acid corrosion resistance of the feed water preheater C/3) is located in the four locations in the flue (12) where low-temperature corrosion is likely to occur. This is a heavy oil-fired boiler that is characterized by being installed.