JPH0523662A - Wet scrubber waste water treatment device - Google Patents

Abstract

PURPOSE:To drastically improve treatment efficiency and to decrease cost by providing a means for spraying a scrubber waste water, in which a heavy metal stabilizing agent is added to make a particle, into a high temp. exhaust gas. CONSTITUTION:In the wet scrubber waste water treatment, a proper amount of a chelete agent or a sulfide is added into the scrubber waste water as the heavy metal stabilizing agent so that the heavy metal contained in the scrubber waste water is a stable compound when solidified. And the scrubber waste water is sprayed from the spraying nozzle 9 of the evaporating chamber 3 to the exhaust gas from the waste heat boiler 2 as particle. The particle, in which water begins to evaporate from the surface by heating and entrainment, is solidified with increase in temp. and is collected in the bag filter 5. An atmospheric temp. at the time of collection of the particle by the bag filter 5 is a temp. not to revolatilize mercury compound contained in the collected solid and to keep drying state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet scrubber wastewater treatment apparatus applied to an incinerator for municipal solid waste, an incinerator for industrial waste, and the like.

[0002]

2. Description of the Related Art FIG. 2 is a conventional wet scrubber wastewater treatment used to treat harmful components mainly composed of mercury contained in wastewater wet scrubber wastewater of exhaust gas in municipal waste incinerators and industrial waste incinerators. It is explanatory drawing of an apparatus. In the figure, the wet scrubber wastewater treatment in this apparatus is performed according to the flow shown in the figure. First, the PH adjusting agent 13 is added to the scrubber water 7 in the mixing tank 15 to adjust the PH, and then the salts for forming precipitates are added. 14 is added. Next, in the settling tank 19, a heavy metal such as mercury is converted into a detoxified substance by using chemicals such as an alkali agent 16 and a polymer flocculant 17, and the precipitated heavy metal sludge 18 is removed. It is adsorbed and removed by.

[0003]

In the conventional wet scrubber wastewater treatment equipment as described above, since the wastewater treatment process is complete, a large site is required for the equipment and harmful heavy metals are coagulated and precipitated. The cost of chemicals and the cost of the chelate resin 20 for adsorbing and removing the remaining mercury and the like are high. In addition, even in the treatment of the removed harmful components, the heavy metal sludge from which the precipitate has been removed is not stable by itself, so treatment such as concrete solidification must be carried out. When it is contained, it is necessary to treat it separately in consideration of salt damage in the river.

[0004]

A wet scrubber wastewater treatment apparatus according to the present invention aims to solve the above-mentioned problems.
The present invention is characterized in that the scrubber wastewater is mixed with a heavy metal stabilizer to form particles and sprayed in high temperature exhaust gas, and a bag filter for collecting the particles sprayed in the exhaust gas.

[0005]

That is, in the wet scrubber wastewater treatment apparatus according to the present invention, the scrubber wastewater is mixed with a heavy metal stabilizer and sprayed as particles into the exhaust gas to be collected by a bag filter. When the particles are sprayed into a high-temperature exhaust gas, heating and entrainment cause evaporation of water from the surface of the particles to increase the concentration, and the particles are collected as solid matter by a bag filter for dry treatment. that time,
Heavy metals contained in the scrubber drainage are also collected as stable solid compounds by the heavy metal stabilizer.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a wet scrubber wastewater treatment equipment according to an embodiment of the present invention. In the figure, the wet scrubber wastewater treatment equipment according to the present embodiment is used for treating harmful components mainly composed of mercury contained in exhaust gas of wet scrubber wastewater in an urban refuse incinerator or an industrial waste incinerator. 1 is incinerator, 2 is waste heat boiler, 3 is
Is an evaporation chamber (flue), 4 is a temperature reducing (chemical injection) chamber, 5 is a bag filter, 6 is a chimney, 8 is a pump, and 9 is a spray nozzle. The wet scrubber wastewater treatment in this device is performed according to the flow shown in the figure. First, an appropriate amount of the heavy metal stabilizer 12 is added so that the heavy metals contained in the scrubber wastewater exist as stable compounds when solidified. A chelating agent or a sulfide (N _a2 S, C _a S, etc.) is mixed with the scrubber drainage, and this scrubber drainage is fed from the spray nozzle 9 of the evaporation chamber 3 into the exhaust gas of 300 ° C. to 500 ° C. from the waste heat boiler 2. The particles are sprayed as particles of the order of microns to 300 microns. Moisture evaporates from the surface of the particles due to heating and entrainment, the concentration increases, and solid particles are finally collected by the bag filter 5. The ambient temperature at which the bag filter 5 collects is 130 ° C. to 16 ° C., which is a temperature at which a mercury compound contained in the collected solid matter does not re-evaporate and is maintained at a dry state.
Set to 0 ° C. In the case where a heavy greenhouse substance contained in the exhaust gas is also taken in and collected by injecting slaked lime etc. by providing a reduced greenhouse 4 between this spraying and collecting, and injecting scrubber wastewater alone The collection efficiency of heavy metals is higher than that.

As the heavy metal stabilizer, heavy metals are stably present in the solution in the evaporation chamber 3 at about 500 ° C., and about 15
At 0 ° C., it is selected so as to exist stably without being decomposed as a solid substance, and the temperature is also set to 130 to 160 ° C. so that the heavy metals are collected as a dried substance. Further, in the drying of the scrubber drainage, the salt concentration, the particle size and the drying temperature have a great influence on the evaporation rate of water droplets, but these conditions are taken into consideration. The feed time is 2 to 4 seconds, and the solution with a salt concentration of about 10% has a temperature of 300 ° C to 500 ° C.
The particles are sprayed into the evaporation chamber 3 as particles having a particle size of several microns to 300 microns. It should be noted that it is necessary to increase the particle size when the temperature rises, and to decrease the particle size when the salt concentration rises.

[0008] Wet scrubber wastewater was actually sampled from a cleaning plant, and mercuric chloride was added to this as a mercury concentration of 1,000.
A solution added with ppm was used as a sample, and this solution was sprayed into an electric furnace in a laboratory to perform a wet scrubber wastewater treatment test. Mercury chelating agent (Epofloc L
-1) 2 equivalents, N _a2 S as a sulfide 5 equivalents, C _a S
Table 1 shows the collection rates of mercury when 2 equivalents of the above were sprayed into a furnace at 500 ° C. and the temperature of the collecting part was changed to 200 ° C., 160 ° C. and 130 ° C.

[0009]

[Table 1] In this way, this device uses scrubber wastewater as waste heat boiler 2
By spraying in the exhaust gas from the plant and performing dry treatment, a wastewater treatment device is not required and a large site is not required. Also, the amount of chemicals used is 1/5 to 1/1 in the conventional wastewater treatment equipment.
It becomes 3. Further, conventionally, it is necessary to carry out concrete solidification of fly ash collected from exhaust gas in addition to solidification of heavy metals in scrubber drainage. Fly ash can be collected together and solidified into concrete. Therefore, it is possible to significantly improve the processing efficiency and reduce the cost as compared with the related art.

[0010]

EFFECTS OF THE INVENTION The wet scrubber wastewater treatment equipment according to the present invention is constructed as described above, and since the scrubber wastewater is dry-processed, it does not require a large site like the wastewater treatment equipment and the amount of chemicals used is Reduce. Further, since heavy metals in wastewater are collected as a stable solid compound, concrete solidification treatment and wastewater treatment are not particularly required.

[Brief description of drawings]

FIG. 1 is a flow chart of a wet scrubber wastewater treatment device according to an embodiment of the present invention.

FIG. 2 is a flow diagram of a conventional wet scrubber wastewater treatment device.

[Explanation of symbols]

 1 Incinerator 2 Waste heat boiler 3 Evaporating chamber 4 Reduced greenhouse 5 Bag filter 8 Pumps 9 Spray nozzle

Claims (1)

Claim: What is claimed is: 1. A means for mixing a heavy metal stabilizer with scrubber drainage to form particles into a high temperature exhaust gas, and a bag filter for collecting the particles sprayed in the exhaust gas. Wet scrubber wastewater treatment equipment characterized by comprising.