JPH0655253B2 - Exhaust gas treatment equipment for waste incinerator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improvement of an exhaust gas treatment device for a waste incinerator,
It can collect most of the harmful substances in the exhaust gas, hardly generate dioxin and dew point corrosion, and can be easily applied to the exhaust gas treatment device using the existing electrostatic precipitator. The present invention relates to an exhaust gas treatment device for a material incinerator.

(Prior Art) Conventionally, an exhaust gas treatment device that combines an electric dust collector mainly for removing dust and a smoke washing device for removing harmful gases such as HCl and SO _x has been used for the exhaust gas treatment of an MSW incinerator. It has been widely used.

However, when the smoke washing device is a so-called wet treatment device that uses a caustic soda solution or the like, it takes a lot of time to treat the smoke washing waste water, and many practical problems arise. This is because harmful substances such as mercury, lead, and cadmium that have been collected are present in the smoke washing wastewater, so removal of these substances is necessary, which increases equipment costs and running costs. The reason is that the treatment agent wastewater may not be discharged.

On the other hand, in order to avoid the above-described problems related to smoke washing drainage, an exhaust gas treating apparatus using a so-called dry type smoke washing apparatus has been developed and put into practical use. An exhaust gas treatment device using this dry type smoke washing device blows slaked lime powder into the flue on the upstream side of the electrostatic precipitator and collects it together with the medium dust in the electrostatic precipitator. It has an excellent practical utility that the removal rate can be achieved.

However, it has recently become clear that the dry type exhaust gas treatment apparatus using the slaked lime powder has a serious defect such as production of dioxin which is a harmful substance.

That is, the conventional electrostatic precipitator keeps the temperature of the exhaust gas in the dust collector at 250 to 300 ° C. or higher in order to prevent the dielectric strength of the insulator from lowering due to the condensation of the exhaust gas. It was found that dioxin was generated in the electric dust collector.

Therefore, it can be said that the electrostatic precipitator is unsuitable as an exhaust gas treatment device for a waste incinerator.As an alternative to this, (a) an exhaust gas treatment device combining a slaked lime powder injection and a bag filter. Alternatively, (b) a reactor (reaction tower) and a bag filter are combined, and a lime slurry is blown into the reactor to form a lime layer on the surface of the bag filter, and when HCl or SO _x passes through this layer. A semi-dry type exhaust gas treatment device has been developed which is designed to absorb into the lime layer.

According to the latter semi-dry exhaust gas treatment equipment, the HCl removal rate is 98%, the SO _x removal rate is 90%, and the dust removal rate is 99.9.
%, Dioxin removal rate 90% and mercury removal rate 70
It has been reported that the amount reaches almost 100%, and it has been clarified that most harmful substances can be efficiently collected.

However, the exhaust gas treating apparatus in which the bag filter is combined has a basic problem in terms of heat resistance of the bag filter, which requires a lot of trouble to repair the treatment equipment.

Further, even if a highly heat-resistant bag filter material is available, there is a problem that the manufacturing cost of the exhaust gas treatment device is significantly increased because the bag filter material is expensive.

Furthermore, from the viewpoint of the material of the bag filter and the prevention of generation of dioxins, it is desirable to keep the exhaust gas temperature at 200 ° C. or lower, but if the exhaust gas temperature is suppressed by using a water cooling pipe or an air preheater, so-called dew point corrosion will occur. There is a difficulty to say.

In addition, in the exhaust gas treatment device of the waste incinerator equipped with the conventional electric dust collector, the exhaust gas temperature is set to 250 to 300 ° C. from the viewpoint of the insulating property inside the electric dust collector as described above. However, there is a problem that the conventional bag filter cannot be applied as it is and the exhaust gas treatment device cannot be easily modified.

(Problems to be Solved by the Invention) The present invention has the above-mentioned problems in an exhaust gas treatment apparatus of a waste incinerator in which a submerged slaked lime powder (or lime slurry) is blown in and a bag filter is combined, that is, If a bag filter with high heat resistance is used, the manufacturing cost of the exhaust gas treatment device will significantly increase, and if the exhaust gas temperature is cooled by a cooler or the like to keep it below 200 ° C, there is a risk of so-called dew point corrosion. It is intended to solve problems such as increase in cost, inability to use bag filters as a substitute for conventional electrostatic precipitators easily and inexpensively, and without using expensive bag filters with high heat resistance. It can be manufactured at low cost and there is no risk of dew point corrosion.
Moreover, the present invention provides an exhaust gas treatment device for a waste incinerator, which can be easily installed as an alternative to an existing electrostatic precipitator and can surely collect or absorb most harmful substances.

(Means for Solving the Problems) In Japan, there are currently about 20 municipal waste incineration plants.
There are many other industrial waste incineration plants. In addition, these existing incineration plants are
Most of them are equipped with an exhaust gas treatment device using an electric dust collector.

However, even if it is found that the electric dust collector is unsuitable for exhaust gas treatment of a waste incinerator as described above, and it is possible to effectively remove harmful substances by using a bag filter instead of the electric dust collector. Due to the exhaust gas temperature, it is difficult to apply the bag filter immediately.

In addition, since an electric dust collector generally has a large body and a large volume ratio in the incinerator, it is almost impossible to separately install a bag filter in addition to the electric dust collector in terms of space.

The present invention was developed against the background of the above-mentioned situation in the exhaust gas treatment apparatus of the conventional waste incinerator, and it can be used not only as a replacement for an existing electric dust collector but also as an internal dust collector. The device can be easily formed by repairing.

That is, according to the present invention, the main body 1 in which the inlet gas duct 5 and the outlet gas duct 6 communicate with each other; is provided on the upstream side in the main body 1, and the exhaust gas G is desired while keeping the temperature of the pipe wall higher than the dew point temperature of the exhaust gas G. A plurality of heat pipes 2 that are cooled to a temperature equal to or lower than the temperature of;
And are the basic configurations of the invention.

(Operation) The exhaust gas G flowing in from the flue is cooled by coming into contact with the heat pipe 2 and reaches a temperature of about 200 ° C. or less and flows into the bag filter 3.

The exhaust gas G is a lime layer 3 formed on the outer surface of the bag filter 3.
It enters the inner surface of the tube through a, passes through the tube, and is discharged into the upper duct 6a.

The dust, heavy metals, HCl, SO _x, etc. in the exhaust gas G are collected or absorbed on the outer surface of the bag filter 3 by the lime layer 3a.

The removed dust particles and the like are dropped downward by blowing air from the inside of the tube of the bag filter 3 in the opposite direction, and are discharged to the outside through the discharging conveyor 7.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 is a vertical cross-sectional view of an exhaust gas treating apparatus for a waste incinerator according to the present invention, in which 1 is a main body, 2 is a heat pipe, 3 is a bag filter, 4 is an inlet straightening plate, and 5 is an inlet. Gas duct, 6 outlet gas duct, 7 conveyor for discharging dust, 8 dust discharging device, 9 pulse air blowing device, 1
0 is a water duct, 11 is a cold water supply port, 12 is a hot water discharge port,
13 is a temperature sensor, 14 is a flow rate adjusting valve, 15 is a controller, 16 is a heat insulating casing, 17 is a soot blower, and the temperature sensor 13, the flow rate adjusting valve 14 and the controller 15 constitute a temperature control device E. .

The main body 1 has an appropriate size according to the amount of exhaust gas treatment, and the main body of an existing electrostatic precipitator can be used as the main body 1 of the exhaust gas treatment apparatus.

That is, in the electrostatic precipitator, the direction electrode 18 and the collector electrode 19 are usually arranged inside the main body 1a as shown in FIG.
a is provided with an inlet gas duct 5a, an outlet gas duct 6a, a dust carrier 7a, and a dust discharge device 8a. Moreover, according to the design of the inventor of the present invention, it is necessary for processing a predetermined amount of exhaust gas. The volume of the bag filter 3 is about 1/2 of the internal volume of the main body of the electrostatic precipitator capable of treating the exhaust gas amount.

Therefore, only the electrode 18 and the dust collecting electrode 19 of the existing electrostatic precipitator are removed to remove the main body 1a, the inlet flow straightening plate 4a, the inlet gas duct 5a, the outlet gas duct 6a, and the dust carrier 7
It is also possible to use the a, the dust discharge device 8 and the like as they are as constituent members of the exhaust gas treatment device of the present invention.

The heat pipe 2 constitutes a cooling device for the exhaust gas G, and is a metal pipe in a vacuum state in which pure water or the like is enclosed. The plurality of heat pipes 2 arranged in a zigzag arrangement in the vertical direction are fixedly mounted with their upper portions 2a protruding inwardly of the heat insulating casing 16.

In this embodiment, the exhaust gas G flowing in at a temperature of about 300 ° C. is cooled to a temperature of about 200 ° C. or lower and sent to the bag filter 3, and the wall temperature of the heat pipe 2 is the dew point of the exhaust gas G. The temperature control device E is used to maintain the heat pipe 2 so that the temperature is maintained above the temperature (about 150 ° C., 5 kg / cm ² ).
The heat absorption amount of is controlled.

The bag filter 3 is formed of a plurality of tube bodies, and is arranged on the downstream side of the main body 1 in the vertical direction. A coating layer 3a of lime is formed on the outer surface side of the bag filter 3, and the exhaust gas G is formed by the lime layer 3a.
HCl and SO _x inside are absorbed.

In the present embodiment, the lime layer 3a is pre-cured on the outer surface of the bag filter 3 by coating, but lime powder is blown into the upstream flue or lime slurry is removed. The lime layer 3a may be formed on the outer surface of the bag filter by blowing.

The upper part of each tube forming the bag filter 3 is communicated with the upper duct 6a, and the exhaust gas G flowing into the tube from the outside rises in the tube and the upper duct 6a.
It is discharged to the outside through a and the outlet duct 6.

The pulse air blowing device 9 removes dust particles and the like adhering to the outer surface of the bag filter 3, and blows air backward from above into the tube of the bag filter 3 to drop the dust particles and the like. .

Next, the operation of the present processing device will be described. Exhaust gas G of about 300 ° C. flowing in from a flue (not shown) through the inlet gas duct 5 is rectified by the inlet rectifying plate 4,
While passing through the heat pipe group, it is cooled to a temperature of about 200 ° C. or lower and flows into the bag filter 3.

That is, when the heat pipe 2 is heated by the high temperature exhaust gas G, the pure water in the lower portion 2b evaporates and the upper portion 2a
Rise inward. The ascendant is cooled by the cooling water W in the water duct 10 and condensed, and flows down along the inner wall surface of the pipe.

In this way, the heat of the exhaust gas G is transferred to the cooling water W, and the temperature of the exhaust gas at the inlet of the bag filter 3 is 200 ° C.
While being cooled below, hot water is discharged from the hot water outlet 12.

The outer wall temperature of the heat pipe 2 must be maintained at a temperature of about 150 ° C. or higher to prevent so-called dew point corrosion.
By adjusting the opening of the flow rate adjusting valve 14 via the controller 15 by the signal from the temperature sensor 13, the bag filter inlet temperature of the exhaust gas G and the heat pipe 2 are adjusted.
The outer wall temperature of each is automatically controlled so as to be within the set value range.

The exhaust gas G cooled to about 200 ° C. or less flows into the bag filter 3 on the downstream side, and flows from the outer surface of the bag filter 3 to the inner surface side.

During this inflow, the lime layer 3a coated on the surface
As a result, HCl and SO _x in the exhaust gas G are absorbed, and heavy metals, dioxins, dust and the like are collected.

Lime, dust particles, and the like adhering to the surface of the bag filter 3 are separated by blowing air from the pulse air blowing device 9 in the opposite direction, and are discharged to the outside via the conveyor 7 and the discharging device 8.

The clean gas is discharged to the outside through the upper duct 6a and the outlet gas duct 6.

Further, the substance adhered to the outer surface of the heat pipe 2 is removed by the operation of the stove blower 17.

According to the exhaust gas treatment test in the actual waste incinerator,
It has been confirmed that harmful substances can be removed at a removal rate almost equal to or higher than that of the conventional semi-dry type exhaust gas treatment apparatus using lime slurry.

(Effects of the Invention) In the present invention, the heat pipe 2 and the bag filter 3 are organically combined to cool the exhaust gas temperature to a desired temperature suitable for the bag filter material. It can be used and the device can be manufactured inexpensively, and most harmful substances contained in the exhaust gas from the waste incinerator can be efficiently removed.

Further, in the present invention, since the heat pipe 2 is used for cooling the exhaust gas G and the outer wall temperature of the heat pipe 2 is maintained at the dew point temperature of the exhaust gas G or higher, the occurrence of dew point corrosion can be completely prevented. I can.

Further, in the present invention, the residual heat recovered by the heat pipe 2 can be used, and the treatment device can be easily formed by modifying the inside of the existing electric dust collector, and the exhaust gas treatment of the existing plant can be performed. The equipment can be easily refurbished.

As described above, the present invention has excellent practical utility.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of an exhaust gas treating apparatus according to the present invention. FIG. 2 is a schematic vertical sectional view of a conventional electrostatic precipitator. 1 ... Main body 2 ... Heat pipe 3 ... Bag filter 4 ... Inlet straightening vane 5 ... Inlet gas duct 6 ... Outlet gas duct 7 ... Container dust discharging conveyor 8 ... Matter dust discharging device 9 ... Pulse air Blow-in device 10 ...... Water duct 11 ...... Cold water supply port 12 ...... Hot water discharge port 13 ...... Temperature sensor 14 ...... Flow rate adjusting valve 15 …… Controller 16 …… Insulation casing 17 …… Sote blower W …… Cooling water G …… Exhaust gas E …… Temperature control device

Claims (5)

[Claims] 1. A body (1) communicating with an inlet gas duct (5) and an outlet gas duct (6); provided on the upstream side in the body (1),
A plurality of heat pipes (2) for cooling the exhaust gas (G) to a temperature below a desired temperature while keeping the temperature of the pipe wall higher than the dew point temperature of the exhaust gas (G); provided on the downstream side of the heat pipe (2) ,
An exhaust gas treatment device for a waste incinerator, which comprises a bag filter (3) for removing dust particles and harmful substances in the exhaust gas (G). 2. A cooling water for cooling a temperature sensor (13) having a heat pipe (2) inserted into the pipe and an upper portion (2a) of the pipe.
The heat pipe provided with a temperature control device (E) consisting of a regulating valve (14) of (W) and a controller (15) to which a signal from a temperature sensor (13) is input. Exhaust gas treatment equipment for waste incinerators in Japan. 3. The exhaust gas treatment device for a waste incinerator according to claim 1, wherein the bag filter (3) is a tubular bag filter having a lime layer formed on the outer surface. 4. Exhaust gas at the inlet of the bag filter (3)
The temperature of (G) is about 200 ℃ or less, and the heat pipe (2)
The temperature of the tube wall is about 150 ° C or higher.
The exhaust gas treatment device for a waste incinerator according to (1). 5. The exhaust gas treatment device for a waste incinerator according to claim 1, wherein the main body (1) is a main body of an existing electrostatic precipitator.