JPH0133644Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a device that processes dust, acidic or alkaline waste discharged from plants such as coal-fired power plants without causing pollution, and in particular strong acids generated within the system. The present invention relates to a device that can effectively dilute sexual fluid.

BACKGROUND ART In thermal power plants, especially coal-fired power plants, large amounts of clinker and fly ash are produced by combustion of pulverized coal and fine grained coal, and their disposal has become a problem. A water jet is preferred for discharging and transporting clinker that accumulates in the slag tank at the bottom of the furnace.
In addition, sealing water is required to seal the slag tank and the bottom of the furnace. On the other hand, the particle size of the debris collected by a dust collector such as an electrostatic precipitator is micron-sized, as is called fly debris, and it is easily blown up, requiring careful handling, and the amount of debris being emitted is large.

As an example, showing these amounts for a boiler unit for a 700MW class coal-fired power plant, clinker is
10T/h, fly ash 80T/h, clinker transport water 300T/h, fly ash humidification water 15-20T/h. In addition, the waste water discharged from the cooling tower of the desulfurization equipment is a strong acid with a pH of 1 to 2, and the amount discharged is
18T/h, and the wastewater from Shitukuna, which concentrates CaSO ₄ (gypsum) produced when SO ₂ and SO ₃ in exhaust gas are treated with CaO, is an alkaline liquid with a pH of 9.0 to 9.5.

As mentioned above, large amounts of fly ash and clinker are discharged from coal-fired power plants, and from the desulfurization process, a sulfuric acid solution containing highly concentrated hydrochloric acid and hydrofluoric acid is produced by the spray water used to cool the exhaust gas, and CaSO is produced by the reaction with CaO. _Four
Due to the treatment and transportation of
It requires a water flow of 350T/h. Some of these wastes are used as valuable materials, but some wastewater and
Both fly ash and clinker must be neutralized before being discharged to prevent secondary pollution. In particular, as the strongly acidic liquid mentioned above is circulated and used for cooling exhaust gas, its acidity increases and causes problems such as corrosion of pipes, so the PH value should be kept almost constant and the acidity should not become too high. It is necessary to take this into account.

In view of the above problems, the purpose of this invention is to provide a device that maintains the acidity of exhaust gas cooling water below a certain value and does not require special water supply from outside the system. .

In short, this idea connects a pipe line that supplies neutralized water extracted from wastewater treatment equipment, water used for transporting sludge and clinker, etc. to the circulation system of exhaust gas cooling water, and provides an almost neutral solution to the exhaust gas cooling water. By adding water, the acidity of the circulating exhaust gas cooling water is maintained at a substantially constant value.

Embodiments of this invention will be described below with reference to the accompanying drawings.

In FIG. 1, exhaust gas from a coal-fired boiler 1 passes through an electrostatic precipitator 2, pipes 3 and 4, a desulfurization fan 5, a heat exchanger 6, and is cooled in a cooling tower 7 of the desulfurization equipment. (not shown). The desulfurized exhaust gas is heated to a predetermined temperature by the untreated gas in the heat exchanger 6, and then passed through the pipe line 9.
and 3 before being released to the outside. The untreated gas in the cooling tower 7 is cooled by spraying cooling water at the throat of the cooling tower, but in addition to this, the cooling water also contains SO ₂ , SO ₃ and other dust, as well as
It also functions to capture HCl, HF, etc. Cooling water is circulated through the cooling tower 7, the cooling tower circulation tank 20, and the pipe line 22 by the circulation pump 21. During this cooling process, it becomes a strongly acidic liquid with a pH of 1 to 2, and sludge increases, so the water is circulated through the pipe line 23. It is configured so that a part of it is constantly extracted and supplied to the wastewater treatment tank 29.

On the other hand, fly ash collected by the electrostatic precipitator 2 is pneumatically transported through a pipe line 13 using pressurized air from a blower 12 and supplied to a silo 14. An appropriate amount of the liquid is sent to the mixer 15 through the pipe 50, humidified and kneaded with spray water from the spray nozzle pipe 15a, and then transferred to the track 1.
6, it is transported to a predetermined location and either dumped or put to good use (for example, added to cement). In addition to being discharged through this pipe 50, the fly ash flows into the pipe 47 and flows from the wastewater treatment tank 29 to the pipe 3.
After being kneaded with the supernatant liquid extracted through Steps 0, 31 and 32 in a mixer 47a, it is supplied to the wastewater treatment tank 29 as an alkaline liquid. In the wastewater treatment tank 29 here, the strong acidic liquid is mixed with an alkaline liquid and neutralized. In this case, an alkaline liquid W ₁ containing CaSO ₄ produced during the desulfurization process may be added. The neutral liquid (water) generated in this neutralization process is supplied to a strong acidic liquid circulation path, for example, the cooling tower circulation tank 20, through pipes 30 and 30a, and is used for diluting the strong acidic liquid. Further, a part of this neutral liquid is transferred to the slag tank 1a through a pipe line 44.
The water can be supplied as sealing water to the bottom of the boiler 1 and as make-up water for the plant. The sludge accumulated at the bottom of the wastewater treatment tank 29 reaches the water jet conveyor 37 through the pipe 52, where it is conveyed by the water flow from the pump 33 into the pipe 35, and is transferred to the dehydrator 3.
8. The clinker in the slag tank 1a formed at the bottom of the boiler is transferred to a water jet conveyor 36.
The sludge is then supplied to the dehydrator 38 by the water flow in the pipe 34 in the same way as the sludge. The clinker and sludge supplied to the dehydrator 38 are dehydrated and then discharged and transported to a predetermined location by the truck 16a. On the other hand, the water used for transportation enters the settling tank 39, where the suspended matter is settled. The aggregated suspended matter is discharged to the outside, and the purified water (nearly neutral) reaches the circulation tank 40 and is pumped to the pump 4.
1, a part of the liquid reaches the strong acid liquid circulation route through a pipe 24, and is used for diluting the strong acid liquid together with the neutralized liquid supplied through the pipes 30 and 30a.
Further, other water is led to the upstream side of the pump 33 through a pipe line 42, and is used without waste as a replenishment of water for clinker and sludge transportation.

By implementing this idea, the strong acidic liquid generated during the exhaust gas cooling process is diluted with neutral water generated within the system, making it possible to inexpensively prevent corrosion of the strong acidic liquid circulation path.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a coal-fired power plant equipped with a device according to this invention. 7... Cooling tower, 24... Reused water introduction pipe,
29... Waste water treatment tank, 30, 30a... Pipe line for introducing neutralized liquid.

Claims (1)

[Scope of utility model registration request] During desulfurization of exhaust gas, the exhaust gas is cooled by circulating cooling water, a portion of the cooling water is neutralized with flyash-containing water in a wastewater treatment tank, and clinker and sludge from the wastewater treatment tank are transported by water. In systems where the water used for water is reused after removing suspended matter, the water circulation path for exhaust gas cooling is connected to the pipe line that supplies the neutralized liquid to the wastewater treatment tank, and the reused water after removing the suspended matter. An exhaust gas cooling water dilution device that connects the pipes that supply the exhaust gas cooling water and replenishes the amount corresponding to the amount of exhaust gas cooling water extracted to dilute the circulating acidic cooling water.