JPS6019057A - Exhaust gas treating apparatus - Google Patents

Abstract

PURPOSE:To make it possible to achieve the improvement in the capacity of a high resistant electric dust collector and the miniaturization of a gas turbine at a stroke, by also using the cooling line of a dust collecting electrode for the heat exchange line of a water tube type gas-gas heater; CONSTITUTION:An electric dust collector 11 equipped with a water cooled electrode and a water tube type gas-gas heater 12 are successively arranged to an exhaust gas flowline and the water cooled electrode of the electric dust collector 11 and the low temp. gas side heat exchanger 12b of the gas-gas heater 12 are connected by a low temp. water recirculation line 15. That is, an inverse ionization phenomenon due to high resistant dust is prevented by bringing the electric dust collector 11 to a water cooled electrode system and the enhancement in the capacity of the electric dust collector can be achieved. In addition, because the water cooled electrode of the electric dust collector is also used for a part of the high temp. gas side heat exchanger of the gas-gas heater, the miniaturization of the high temp. gas heat exchanger 12a can be achieved and, by utilizing water in a recirculation system, the replenishment of cooling water to the electric dust collector and exhaust water therefrom are reduced or dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a treatment device for treating exhaust gas from a coal-fired boiler or the like.

This type of conventional exhaust gas treatment bag jη has a denitrification device (not shown), an air preheater (not shown), a dry electrostatic precipitator 1, and a high-temperature gas side heat exchanger of the gas gas heater 2 for reheating in the exhaust gas flow path. 2a, a wet desulfurization device 3, a low temperature gas side heat exchanger 2b of the gas gas heater 2, and a chimney 4 are arranged in this order.

Here, the water tube type gas heater 2 connects the high temperature gas side heat exchanger 2a and the low temperature gas side heat exchanger 2b with a cold/hot water circulation line 5, and exchanges heat with exhaust gas using water as a medium by a pump (not shown). This is what we do.

In this treatment equipment, the exhaust gas from the boiler is led to an air preheater and exchanged with combustion air to cool it down to about 130°C to 160°C, and then removed by electrostatic precipitator. High temperature gas side heat exchanger 2a of gas heater 2
The high-temperature exhaust gas at the outlet of the electrostatic precipitator I is further cooled by heat exchange with water, and is then led to the wet desulfurization device 3.

In the wet desulfurization device 3, SO in the exhaust gas is absorbed and removed by SO and an absorbing liquid], and residual fly ash in the exhaust gas is further removed in this gas-liquid contact process. Next, the exhaust gas from which SO2 and fly ash have been removed is guided to the low temperature gas side heat exchanger 2b of the gas heater 2. Here, the temperature of the exhaust gas lowered by 7Wh with the S02 absorption liquid etc. in the treatment process of the wet desulfurization apparatus 3 is calculated by 1j71 due to heat exchange with water. This means that when the smoke is released into the atmosphere from the chimney 4, the moisture content is reduced, suppressing the generation of white smoke and increasing the diffusion due to temperature momentum in the atmosphere.

However, in the gas heater 2, the high-temperature exhaust gas at the outlet of the electrostatic precipitator 1 must be guided to the wet desulfurization device 3 at a low temperature, so the heat exchange capacity becomes large and there are problems with installation space, cost, etc.

On the other hand, regarding the dust contained in the exhaust gas of coal-fired boilers, in conventional dry type electrostatic precipitators, if the electrical resistance of the dust to be collected exceeds 1011~'2, a reverse ionization phenomenon occurs, and the amount of dust collected per surface area of the dust collecting electrode is It is known that the collection performance deteriorates significantly.

For this reason, the following countermeasures (a) to (e) are being considered.

B) Extremely increase the area of the dust collection electrode.

-) Lower the electrical resistance of the dust by raising the gas temperature or refining the gas.

(c) Perform special charging such as pulse charging and intermittent charging.

2) Use a moving electrode to keep the surface of the dust collecting electrode clean so that dust does not accumulate on it, and avoid reverse ionization on the dust collecting electrode.

(Water-cooling the dust collecting electrode [7) Lower the temperature of the dust hot hole to the low temperature region of the temperature-resistivity curve to avoid reverse ionization on the dust collecting electrode.

The present invention has been made by focusing on the cooling method for the 15-dust electrode described in (e), and the cooling line of the dust collecting electrode is also used as the heat exchanger line of the water tube type gas gas heater, thereby reducing high resistance dust. An object of the present invention is to provide an exhaust gas treatment device that can improve the performance of an electrostatic precipitator and downsize a gas heater at the same time.

That is, the present invention has an electric precipitator equipped with a water-cooled electrode in the exhaust gas flow path and a water tube type gas heater installed in jIli'H, and the water-cooled electrode of the electric collector 1+;q and the low temperature gas side of the gas gas heater. Connect the heat exchanger with a cold/hot water circulation line [
, is taken as 4'& sign.

The present invention will be explained below with reference to the drawings.

FIG. 2 is an explanatory diagram showing an example of a boiler exhaust gas treatment device. This treatment equipment includes a denitrification device (not shown) in the exhaust gas flow path, an air preheater (not shown), a water-cooled dry type electrostatic precipitator with dust collecting electrodes, and a water tube type for reheating that heats the high temperature gas side of the gas heater I2. The exchanger 12a, the wet desulfurization device 13, the low-temperature gas side heat exchanger Job of the gas gas heater 12, and the chimney 14 are arranged in this order (7). Furthermore, the electrostatic precipitator II
The water-cooled dust collecting electrode, the high-temperature gas side heat exchanger 12a, and the low-temperature gas side heat exchanger 12b are connected by a cold/hot water circulation line 15 to exchange heat with the waste waste.

This exhaust gas treatment device uses an electrostatic precipitator II to remove fly ash from the boiler exhaust gas, and a dust collection electrode section cools the exhaust gas by heat exchange.

Furthermore, this waste heat is exchanged again with the heat exchanger 12a on the front side heat exchanger 12a to the heat exchanger 120 for cooling.
, to the wet desulfurization equipment 13. Next, after removing SO7 and fly ash from the exhaust gas in the wet desulfurization equipment I3,
The exhaust gas is guided to the low-temperature gas side heat exchanger J2b of the gas gas heater 12, heated, and discharged from the chimney 14 to the atmosphere.

On the other hand, the water in the cold/hot water circulation line 15 is first collected by the electrostatic precipitator I.
After the heat of the gas J]t is absorbed by the actual open electrode section of t, the heat is further absorbed by the high temperature gas side heat exchanger 12a of the gas gas heater 12 and the temperature is increased by j-1. The heated water then loses heat to the low-temperature J-I gas in the low-temperature gas side heat exchanger 12b of the gas-gas heater 12, and its temperature decreases. After that, the temperature is lowered and the water is poured into the dust collecting electrode part of the electrostatic precipitator II, and the circulation is repeated.

However, according to this processing device, by making the electrostatic precipitator II a water-cooled electrode, the reverse ionization phenomenon caused by high-resistance dust can be prevented from rain, and the performance of the electrostatic precipitator II can be improved and the size of the electrostatic precipitator II reduced. More '1B collection! Since the water-cooled electrode of the 3tt doubles as a part of the high-temperature gas side heat exchanger of the gas gas heater, the high-temperature gas side heat exchanger 12a can be made smaller, and by recycling water, electricity can be Dust collector cooling make-up water and wastewater are reduced and no longer necessary.

Figure 3 shows another real gun (!'!l) of the present invention. In this processing device, the water-cooled electrode of the electrostatic precipitator FJ also serves as the high-temperature gas side heat exchanger of the gas gas heater, and this structure In this case, there is no need to separately provide a heat exchanger on the high temperature gas side of the gas heater, and the processing apparatus can be further simplified.

As explained above, the electrostatic precipitator 1 has a water-cooled electrode structure so that it also serves as a heat exchanger on the high-temperature gas side of the gas-gas heater. It has remarkable effects, such as being able to achieve

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional exhaust gas treatment device, FIG. 2 is an explanatory diagram of an exhaust gas treatment device showing an embodiment of the present invention, and FIG.
The figure is an explanatory diagram of an exhaust gas treatment device showing another practical example of the present invention.
...Gas gas heater J2a...Hot gas side heat exchanger 12b...Low temperature gas side heat exchanger 13...Wet desulfurization device I4...Chimney 15...Cold/hot water circulation line Applicant's sub-agent Patent attorney “Takehiko Suzue■ Figure 2;!'r?31 animals

Claims (1)

[Claims] 5. Electric precipitator with water-cooled electrode in the exhaust gas flow path and water tube type. 1. An exhaust gas treatment device characterized in that a water-cooled electrode of an electrostatic precipitator and a low-temperature gas side heat exchanger of a gas-gas heater are connected by a cold/hot water circulation line.