JPH07103978B2 - How to prevent white smoke when incinerating garbage - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing white smoke in a refuse incineration system for treating a large amount of household garbage and the like.

[0002]

2. Description of the Related Art In a conventional refuse incineration system, it is disliked that the waste gas at the time of incinerating the refuse is emitted as white smoke. Therefore, as a method for preventing the white smoke, for example, FIG.
As shown in, waste gas 21a (8
50 to 950 ° C.) in the water injection chamber 22 to 300 to 400 ° C., and the primary cooled waste gas 21 b is cooled by the air preheater 2.
The heat is exchanged at 3 to perform secondary cooling to 300 to 350 ° C, and the secondary cooled waste gas 21c is subjected to heat exchange at the white smoke prevention air preheater 24 to be tertiary cooled to 200 to 220 ° C, and the tertiary cooling is performed. The waste gas 21d was purified by the dust collector 25. In this dust collector, in order not to deteriorate the dust collecting performance, the dust collector inlet temperature is regulated so as to be equal to or lower than a certain value as described above.

The purified waste gas 21e is discharged by the chimney 26. In this case, the waste gas 21e is discharged.
The e contains a large amount of water in the garbage and water vapor produced by the cooling water injected to cool the waste gas. When the water vapor is released into the atmosphere, if it is below the dew point under atmospheric conditions, the waste gas The water vapor inside condenses to form white smoke. The white smoke itself is harmless, but it may seem that it contains some harmful gas due to its location and appearance. Therefore, in order to prevent this white smoke, the temperature of the waste gas is increased and the relative moisture content is decreased by combining the preheated air with the waste gas at the time of discharge.

Therefore, the white smoke preventing air preheater 24
The cold gas 27a (20 ° C) is taken into the waste gas 21
By preheating with c, and combining this preheated air 27b (180 ° C.) with the waste gas 21e, the waste gas with high water vapor concentration is diluted with air with low water vapor concentration,
I tried to prevent white smoke. In addition, the incinerator 20
Is supplied with preheated air 27c (180 to 230 ° C.) of the air preheater 23 as combustion air.

[0005]

However, in this conventional method, since the cold smoke 27a is supplied to the white smoke prevention air preheater 24, the temperature rise of the preheated air 27b is also low, and therefore, the chimney is removed from the chimney. It is not possible to raise the temperature of the waste gas to be released and the water vapor temperature falls to the dew point,
There was a problem that white smoke was easily generated. Further, in this case, as described above, since the dust collector inlet temperature is regulated so as to be equal to or lower than a certain value, in high-calorie trash in which the temperature in the incinerator becomes high, white smoke is generated by cooling by increasing the amount of water injection. It may be a cause of generation, and if the waste gas temperature is lowered by increasing the heat exchange amount of the combustion air, the temperature inside the furnace becomes higher and the thermal balance may be difficult to obtain.

Further, since cold air is supplied to the white smoke preventing air preheater 24, the temperature of the waste gas passage side pipe wall near the cold air inlet is dewed by corrosive gas contained in the waste gas. It easily enters the area of the point (low temperature corrosion area: 130 to 150 ° C. or less), and the corrosive gas condensed on the tube wall accelerates the aging of the tube wall. For this reason, the white smoke prevention air preheater 24
There was a problem that the service life of was shortened.

The present invention has been made in order to solve the above conventional problems, and its object is to prevent the temperature of the pipe wall through which the waste gas is passed from entering the low temperature corrosion region. While improving the service life of the white smoke prevention air preheater, the temperature of the discharged waste gas is raised and the relative moisture content is lowered to prevent white smoke. It is to provide a smoke prevention method.

[0008]

As means for achieving the above object, in the method for preventing white smoke during refuse incineration according to the present invention, waste gas from a refuse incinerator is primarily cooled in a water injection chamber. Then, the primary cooled waste gas is heat-exchanged with the air preheater for secondary cooling, and the secondary cooled waste gas is heat-exchanged with the white smoke prevention air preheater for tertiary cooling and tertiary cooling. A method for preventing white smoke at the time of incinerating waste, which purifies waste gas with a dust collector, and joins the preheated air of an air preheater for white smoke when releasing the purified waste gas with a chimney, A preheater for exchanging heat between the preheated air of the air preheater and the cold air to cool the preheated air of the air preheater is provided between the white smoke prevention air preheater and the waste gas flow path, and the preheated air cooled by the preheater is incinerated. The preheated cold air is supplied to the furnace and the preheated cold air is preheated to prevent white smoke. It was adopted how to use for heat exchange.

[0009]

Function: The high temperature waste gas from the refuse incinerator is exchanged with heat by passing it through the water injection chamber, the air preheater and the white smoke prevention air preheater. The air preheated by the preheater provided between the air preheater and the white smoke prevention air preheater is supplied to the white smoke prevention air preheater, and here, the air is further preheated by the waste gas. In this case, even if the waste is high-calorie waste, the waste gas temperature is lowered to the temperature regulated by the dust collector by performing the third cooling with the white smoke prevention air preheater via the preheater, It does not reduce the dust performance and does not increase the amount of water injection, so white smoke prevention is improved,
Excellent thermal balance can be set. Then, the re-preheated air is combined with the waste gas after the dust collector to raise the temperature of the waste gas and reduce the relative moisture content, whereby white smoke can be prevented.

At that time, the air inlet temperature of the white smoke prevention air preheater is the temperature of the preheated air of the air preheater,
The temperature of this air preheater is higher than that of cold air by passing the high-temperature waste gas that has been primarily cooled in the water injection chamber, so the temperature of the waste gas passage side pipe wall of the white smoke prevention air preheater Is sufficiently outside the low temperature corrosion area. For this reason, it is possible to prevent white smoke from being generated in the discharged waste gas while preventing the white smoke prevention air preheater from rapidly deteriorating and improving the service life.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a flow sheet showing a method for preventing white smoke in the refuse incineration system of the present invention, in which 1 is an incinerator, 2 is a water injection chamber, 3 is an air preheater, 4 is a preheater, and 5 is countercurrent white smoke. A preventive air preheater, 6 is a dust collector, and 7 is a chimney.

In this system, the waste gas 8a (850 to 950 ° C.) discharged from the incinerator 1 is passed through the water injection chamber 2 to generate 4
Primary cooling is performed at 00 to 450 ° C. Waste gas that has been primarily cooled 8
b is secondarily cooled to 350 to 380 ° C. through the air preheater 3. The waste gas 8c that has been secondarily cooled is thirdly cooled to 160 to 200 ° C. through the white smoke prevention air preheater 5. Then, after the waste gas 8d that has been tertiary-cooled is purified by the dust collector 6, the purified waste gas 8e is discharged to the outside air by the chimney 7.

Next, a white smoke prevention method using this system will be described. First, in the water injection chamber 2, the temperature of the waste gas 8b, which has been cooled primarily by reducing water injection as compared with the conventional method, is set to the conventional value (300 to 4).
The temperature is set higher than 400 ° C (400 to 450 ° C). Next, in the air preheater 3, the cold air 9a (20
(° C) is heat-exchanged with the primary-cooled waste gas 8b to obtain preheated air 9b at 350 to 400 ° C.

In the preheater 4, the cold air 10a (20.degree. C.) taken in is heat-exchanged with the preheated air 9b, and after the preheated air 10b of about 100.degree.
The preheated air 9b lowered to 0 to 250 ° C. is supplied to the incinerator 1 as combustion air.

Then, the white smoke prevention air preheater 5 takes in the preheated air 10b of the preheater 4 and heat-exchanges it with the secondary cooled waste gas 8c.
After preheated air 10c at 0 ° C, it is combined with the waste gas 8e purified by the dust collector 6.

In this case, in the pipe wall of the passage side of the secondary-cooled waste gas 8c of the white smoke prevention air preheater 5, the waste gas side is 160 to 200 ° C. and the preheated air side is 100 ° C. or more as the preheating air inlet temperature. Therefore, the pipe wall temperature is approximately 1
The pipe wall can be protected from low temperature corrosion by securing at 50 ° C or higher. Moreover, in the chimney 7, the waste gas 8 of 160-200 degreeC
Since the preheated air 10c of 200 to 240 ° C. is joined to e and is released to the atmosphere, by raising the temperature at the time of release from the conventional (combining the preheated air of 180 ° C. with the waste gas of 200 to 220 ° C.), By reducing the water injection for primary cooling by the amount of heat consumed by the preheater 4, it is possible to reduce the relative moisture content and prevent the waste gas from becoming white smoke. In this case, fuel or the like for reheating is unnecessary.

As described above, in the system of this embodiment, it is possible to prevent the white smoke of the waste gas while achieving a long life without changing the tube material and grade of the air preheater for preventing white smoke. . By providing a preheater in this system, a thermal balance with excellent controllability can be set for changes in the amount and quality (water content) of waste gas, regardless of high-calorie waste or low-calorie waste. With high-calorie waste, the amount of waste gas heat increases and the amount of water injection also increases.
On the contrary, the conditions for preventing white smoke become severe, but the effect in that case becomes greater. It can be effectively used in winter and rainy season.

The embodiment of the present invention has been described above.
The specific method of the present invention is not limited to this embodiment, and the present invention includes a design change and the like within a range not departing from the gist of the invention.

For example, the set temperature of each part is arbitrary, and the point is that a preheater for preheating the preheating air taken in by the white smoke prevention air preheater 5 is provided, and water injection is reduced by the amount of heat consumed by it. You can do it like this.

A bypass may be provided for each heat exchanger as appropriate. In this case, the variations that can be dealt with even when the incineration heat amount load change occurs are expanded.

The air preheater and the white smoke prevention air preheater may be replaced with each other.

[0022]

As described above, in the method for preventing white smoke at the time of incineration of waste according to the present invention, since the above method is adopted, the inlet temperature of the preheating air in the air preheater for preventing white smoke is kept low. By setting it higher than the corrosive region, it is possible to prevent the white smoke of the waste gas while achieving a long service life of the white smoke preventing air preheater.

It is possible to set a thermal balance with excellent controllability against changes in the amount of waste gas and quality (moisture) with respect to changes in the calorie of waste, and therefore, even with high-calorie waste, there is less heat than before. Since the amount of water injection is sufficient, the white smoke prevention effect is great even in that case.

It is particularly effective in the winter season and the rainy season when white smoke is likely to occur. The amount of water used for the primary cooling is small, and the fuel for reheating is not required, which is economical.

[Brief description of drawings]

FIG. 1 is a flow sheet showing a refuse incineration system according to an embodiment of the present invention.

FIG. 2 is a flow sheet showing a conventional refuse incineration system.

[Explanation of symbols]

 1 Incinerator 2 Water injection chamber 3 Air preheater 4 Preheater 5 Countercurrent white smoke prevention air preheater 6 Dust collector 7 Chimney 8a Waste gas from the incinerator 8b Primary cooled waste gas 8c Secondary cooled waste gas 8d Thirdly cooled waste gas 8e Purified waste gas 9a Air cooler taken into the preheater 9b Preheated air provided with the air preheater 10a Cold air taken into the preheater 10b Preheated air provided with the preheater 10c White smoke prevention air Preheated air provided by the preheater

Claims (1)

[Claims] 1. Waste gas from a refuse incinerator is used in a water injection chamber.
Secondary-cooled, primary-cooled waste gas is heat-exchanged with an air preheater for secondary cooling, secondary-cooled waste gas is heat-exchanged with a white smoke prevention air preheater for tertiary cooling, and tertiary cooling is performed. A method for preventing white smoke at the time of incinerating waste, in which the cooled waste gas is purified by a dust collector, and the preheated air of an air preheater for white smoke prevention is joined when the purified waste gas is released by a chimney. A preheater for exchanging heat between the preheated air of the air preheater and the cold air to cool the preheated air of the air preheater between the air conditioner and the white smoke prevention air preheater, and the preheated air cooled by the preheater Is supplied to an incinerator, and cold air preheated by a preheater is used for heat exchange of the white smoke prevention air preheater.