JPS61129028A - Apparatus for treating exhaust gas - Google Patents

Abstract

PURPOSE:To obtain the title apparatus requiring no large equipment, having high removal efficiency and capable of widely corresponding to the change in the property of exhaust gas or the alteration of a prescribed value, by providing a cage mill, which diffuses an absorbent throughout exhaust gas, on the way of an exhaust gas duct. CONSTITUTION:The absorbent supplied from an absorbent supply apparatus 6 is stirred and crushed by the cage mill provided on the way of the exhaust duct 1 of an urban garbage incinerator and discharged into exhaust gas at a high speed to be diffused therein. When exhaust prescription is enforced, water is supplied to the absorbent from a humidifier 14 and the wetted absorbent kneaded by a screw feeder 13 is supplied to the cage mill 7. The wetted absorbent is contacted with exhaust gas in a reaction part 8 and perfoms absorbing reaction to be converted to a dry powder which is, in turn, collected by an electric precipitator 2. In this case, the same removal ratio of harmful gas as a semi-dry system is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for treating harmful gases such as HCl in the exhaust gas of municipal waste incinerators, etc., and a cage mill is provided in the exhaust gas duct to remove the harmful gases. This improves the removal efficiency by diffusing the absorbent into the exhaust gas.

[Conventional technology]

In general, municipal waste contains vinyl chloride, salt in kitchen waste, and other miscellaneous substances, so the exhaust gas from municipal waste incinerators contains harmful gases such as HCI and SOx. In particular, HCI has a number of

The concentration is as high as 100 to 2000 ppm, and this emission is regulated by law. Conventionally, devices for collecting and removing harmful gases include wet gas treatment equipment such as water washing, injecting powdered absorbent such as slaked lime into the exhaust gas duct, and collecting the reactive absorbent in a subsequent dust collector. Dry gas treatment equipment, semi-dry gas treatment equipment was used in which slaked lime slurry was sprayed into the evaporation reaction tower and the reaction product was collected as dry powder in a dust collector.

[Problem that the invention seeks to solve]

Wet gas treatment equipment has a high removal rate, but requires separate wastewater treatment and is expensive to repair due to corrosion caused by hydrochloric acid, etc. On the other hand, dry gas treatment equipment has low equipment costs, but The removal rate is low, and it is possible to comply with the regulation of 430 ppm at the outlet, but it is necessary to strengthen the emission regulation to prevent pollution (for example, 200 ppm).
Even if the amount of absorbent is increased, it is not possible to sufficiently meet the additional regulations such as ppm or less. On the other hand, semi-dry gas treatment equipment has the advantage that it has a higher removal rate than the dry type, can comply with stricter regulations, and does not require wastewater treatment like the wet type.

However, this semi-dry type also requires a large evaporation reaction tower to completely dry the slaked lime slurry, and if there are large changes in the amount of exhaust gas, temperature, or HCl5 degree, the concentration of the slurry It is difficult to adjust the amount of spray and the amount of spray, and if the amount of exhaust gas decreases or the temperature becomes low, the slurry will not be generated completely, and there is a risk that the slurry will stick to downstream equipment and clog the spray nozzle.

This invention solves the above-mentioned problems in an exhaust gas treatment device.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas treatment device that does not require large-scale equipment and has a high removal rate. The purpose of the present invention is to provide an exhaust gas treatment device that can be used in a wide range of applications.

[Means for solving problems]

The exhaust gas treatment device of this invention is provided with a cage mill that diffuses the absorbent supplied from the absorbent supply device into the exhaust gas in the middle of the exhaust gas duct connected to the dust collector, and according to the properties and regulation values of the exhaust gas. Exhaust gas treatment is performed by supplying dry or humidified absorbent from a supply device to a cage mill.

[Effect]

In the gas treatment device of this invention, the absorbent is caged.

Because the rotor of the mill crushes, stirs, and diffuses into the exhaust gas, even when using a dry absorbent, the contact efficiency is better than that of conventional dry gas treatment equipment (higher removal rate, and even higher removal rates are required). By supplying a humidifying absorbent to a cage mill, it is possible to achieve the same removal rate as a semi-dry gas treatment device without requiring special equipment such as an evaporation reaction tower, and without problems such as nozzle clogging. .

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. 1st
The figure is an explanatory diagram showing the configuration of an exhaust gas treatment device that is an embodiment of the present invention, in which an exhaust gas duct 1 of a municipal waste incinerator (not shown) is connected to an electrostatic precipitator 2, and the dust collector A processing gas duct 3 is connected from the vessel 2 to a chimney 5 via an exhaust fan 4.

A cage mill 7 is provided in the middle of the exhaust gas duct 1 to diffuse the absorbent supplied from the absorbent supply device 6 into the exhaust gas, and the portion of the exhaust gas duct 1 from the cage mill 7 to the electrostatic precipitator 2 is a reaction section 8. is formed.

The absorbent supply device 6 includes an absorbent silo 11 for storing absorbent carried in by a tank car 10 for transporting absorbent, a rotary valve 12 for cutting provided at the bottom of the absorbent silo 11, and a rotary valve 12. A screw feeder 13 transports the absorbent cut out and feeds it into the cage mill 7.
and a humidifier 14 that supplies water and humidifies the absorbent in the screw feeder 13.

The screw feeder 13 has a plurality of screws 15 arranged in parallel inside the casing 1 and 6, and functions simply as a feeder when supplying dry absorbent to the cage mill 7, and functions only as a feeder when supplying humidified absorbent. The absorbent supplied with moisture from the humidifying device 14 is stirred, kneaded, and humidity-controlled, and then introduced into the cage mill 7.

The cage mill 7 has a structure similar to that used in a known ore flash drying device, and a cage-shaped rotor 18 provided in a casing 17 rotates at high speed to agitate and crush the introduced absorbent. It is released into the exhaust gas at high speed and diffused.

If emission regulations are not strict, supplying dry absorbent to the cage mill 7 will allow more complete diffusion in the reaction section 8 than in the conventional dry system, improving the removal rate of harmful gases and reducing the amount of absorbent. Usage is reduced.

When the discharge regulation is strengthened, water is supplied from the humidifier 14 to the absorbent, and the humidified absorbent kneaded by the screw feeder 13 is supplied to the cage mill 7. The cage mill 7 sufficiently stirs and crushes the humidifying absorbent and releases it into the exhaust gas, and the humidifying absorbent contacts the exhaust gas in the reaction section 8 to perform an absorption reaction and is dried to become a dry powder, which is then collected for dust collection. It is collected by instrument 2. In this case, this exhaust gas treatment device can obtain the same harmful gas removal rate as the semi-dry type, and can also comply with regulations of 1100 pp or less. Moreover, since the humidifying absorbent is supplied to the cage mill 7 by the screw feeder 13, a spray nozzle is unnecessary and troubles such as nozzle clogging do not occur.

In addition to being able to respond to changes in regulatory values as described above, this exhaust gas treatment equipment supplies a humidifying absorbent to ensure a high removal rate during steady operation when the incinerator exhaust gas is high temperature and contains a large amount of HCl and other substances. When the flue gas is at a low temperature and the amount of harmful gas generated is small, such as when an incinerator is started up or a buried fire is started, it is possible to switch operation to prevent adhesion to the dust collector and solidification by supplying dry absorbent. It is.

In addition, in this embodiment, one screw feeder 13
The humidifying absorbent and the dry absorbent are switched by supplying and stopping the humidifying device 14, but the screw feeder is arranged in two rows, one for the humidifying absorbent and the other for the dry absorbent, and switching is performed using a damper or the like. You can also do it like this.

〔Effect of the invention〕

Since the exhaust gas treatment device of the present invention is configured as described above, it can achieve a high removal rate of harmful gases without requiring equipment such as a large evaporation reaction tower, and is widely compatible with changes in the properties of exhaust gas and changes in regulatory values. This can prevent operational troubles such as nozzle clogging, undried slaked lime slurry adhering to the dust collector, and assimilation.

[Brief explanation of the drawing]

FIG. 1 is an inventive diagram showing the configuration of an exhaust gas treatment device that is an embodiment of the present invention. In the figure, 1 is an exhaust gas duct, 2 is an electric precipitator, 6 is an absorbent supply device, 7 is a cage mill, 11 is an absorbent silo, 12
1 is a rotary valve, 13 is a screw feeder, and 14 is a humidifier.

Claims (2)

[Claims] (1) An exhaust gas treatment device characterized in that a cage mill is provided in the middle of an exhaust gas duct connected to a dust collector to diffuse an absorbent supplied from an absorbent supply device into the exhaust gas. (2) The exhaust gas treatment device according to claim 1, wherein the absorbent supply device includes a humidifying device and can selectively supply a humidified absorbent and a dry absorbent.