JPS5841892B2 - Hiendatsuri Yuhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of downsizing and reducing operating costs of direct gypsum recovery flue gas desulfurization equipment that uses calcium carbonate or slaked lime as an absorbent. When containing impurities such as ash, a dust removal tower was installed to separate the dust or fly ash, and then an absorption tower was used to desulfurize and obtain high quality gypsum.
This invention relates to a flue gas desulfurization method that performs desulfurization and dust removal only in an absorption tower and separates dust, fly ash, etc. from gypsum in the gypsum recovery stage to obtain high-quality gypsum.

In the conventional direct gypsum recovery flue gas desulfurization equipment, as shown in the flowchart in Figure 1, the flue gas from gas generation source a is
The exhaust gas fan B increases the pressure and enters the cooling dust removal tower C.
The gas is cooled and the dust in the exhaust gas is separated, and the dust collected in the liquid is separated and taken out through a filter g, and the gas leaving the cooling dust removal tower C is sent to an absorption tower d. It is desulfurized.

The desulfurized gas is mixed with the gas from the hot air generator e and released into the atmosphere from the chimney f, while the liquid in the absorption tower d contains calcium sulfite, which is produced by the reaction between the absorbent and sulfur oxide,
It is a slurry liquid of calcium sulfate, and a part of the slurry liquid is sent to the oxidation tower, where the calcium sulfite is oxidized and becomes a gypsum slurry liquid.

The gypsum slurry liquid is sent to the centrifuge i and separated into gypsum and the r liquid, and the f liquid is fed back to the absorption tower d and reused as an absorption liquid, while the gypsum j separated by the centrifuge i is Used for plasterboard, cement, etc.

The above conventional equipment is a method for obtaining high-quality gypsum by collecting dust and fly ash in the gas in the dust removal tower C, but the soot concentration in the gas is higher than that in the collected liquid. Since the dust removal tower C is extremely low, the cost of equipment such as the dust removal tower C is higher compared to the method of desulfurizing dust removal in the absorption tower d and separating soot from the liquid side or recovered gypsum rather than installing the dust removal tower C, and the pressure loss of the dust removal tower C. The gypsum separated by the centrifuge 1 has a moisture content of about 10%, which increases the weight and transportation cost, and also causes adhesion during handling. However, there were problems such as the fact that the process was extremely time-consuming.

The present invention can solve the above-mentioned problems of the conventional system.The exhaust gas is guided to the absorption tower, where absorption and desulfurization and dust removal are simultaneously carried out.The aqueous solution in the absorption tower is transferred to the oxidation tower. After coarsening the gypsum crystals, the gypsum is introduced into a centrifuge to remove liquid, and the gypsum mixed with the collected dust and fly ash is classified after drying using differences in particle size and specific gravity. This relates to a flue gas desulfurization method characterized by extracting high-purity gypsum.

The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a flowchart showing an example of the present invention, in which 1 is a gas generation source, 2 is an exhaust gas fan, 3 is an absorption tower, and 4 is a flowchart showing an example of the present invention.
is a hot air generator, 5 is a chimney, 6 is an oxidation tower, γ is a centrifugal separator, 8 is a dryer, 9 is a classifier, 10 is a dust collector, 11 is an exhaust fan, 12 is makeup water, 13 is an absorbent, 14 is plaster,
15 indicates fly ash and dust.

The exhaust gas from the gas generation source 1 is induced to be pressurized by the exhaust gas fan 2 and enters the absorption tower 3, where the gas is cooled, dust removed, and desulfurized, mixed with hot air from the hot air generator 4, heated, and sent out from the chimney 5. 3 released into the atmosphere, 1 absorbent 13 and make-up water 1
2 is put into the absorption tower 3, so the liquid in the absorption tower 3 becomes an aqueous solution containing calcium sulfite, calcium sulfate, dust, etc., and is further sent to the oxidation tower 6, where the calcium sulfite turns into calcium sulfate and contains gypsum, dust, etc. becomes a containing aqueous solution.

The solution is then led to a centrifuge 7 where it is separated into solids such as gypsum and dust and r-liquid.The liquid is fed back to the absorption tower 3 and reused, while the separated solids such as gypsum and dust are separated. Since it contains about 10% water, it is dried in the dryer 8.

The solid content after drying is classified by a classifier 9 using exhaust gas or air from the dryer 8.
The particles are classified using differences in particle size and specific gravity.

Since the gypsum 14 in the solid content is coarsened in the oxidation tower 6, the particles are relatively large with a size of 50 to 100μ (microns), while dust etc. are relatively small with a size of about 1μ to 20μ, so the particles are coarsened in the oxidation tower 6. The gypsum 14 is separated and recovered as a solid content, and the log gas from the classifier 9 is separated into dust and fly ash 15 by the dust collector 10 and discharged into the atmosphere from the exhaust fan 11.

As the heat source for the dryer 8, heavy oil or gas may be separately combusted, steam may be used, the gas after the exhaust gas fan 2, the gas from the hot air generator 4, or the gas generation source may be a boiler. In this case, using the air after the air heater can save fuel and utilize waste heat, and since the temperature in the dryer 8 is usually over 100°C, even if the solid content after centrifugation contains water, it is almost zero. Can be placed nearby and transport weight is 1
It is reduced by about 0% and the plaster does not stick to equipment, making it easier to handle.Furthermore, when using plaster for plasterboard or segments, it must be fired, but since the moisture content is low, fuel for firing can be saved. .

It should be noted that the present invention is not limited to the above-mentioned embodiments, and various changes can be made without departing from the gist of the present invention.

According to the above-described flue gas desulfurization method of the present invention, (1) a dust removal tower etc. are not required, making the device more compact and lower in price, (ii) operating costs are reduced, and (iii) a dryer is used. Therefore, the amount of adhering water is close to zero, the weight of the gypsum is reduced, and there is no adhesion, making transportation and handling easier. At the same time, the gypsum is guided to an oxidation tower to coarsen its crystals, and then dehydrated and dried. This is a simple means of classifying gypsum mixed with dust and fly ash by utilizing the difference in particle size and specific gravity. It is possible to extract high-purity gypsum by classifying the gypsum.

etc., exhibits various excellent effects.

[Brief explanation of drawings]

FIG. 1 is a flowchart of a conventional direct gypsum recovery flue gas desulfurization equipment, and FIG. 2 is a flowchart showing an embodiment of the present invention. 1 is a gas generation source, 2 is an exhaust gas fan, 3 is an absorption tower, 6 is an oxidation tower, γ is a centrifugal separator, 8 is a dryer, 9 is a classifier, 1
0 is a dust collector.

Claims (1)

[Claims] 1. The exhaust gas is led to an absorption tower where absorption and desulfurization and dust removal are performed at the same time, and the aqueous solution in the absorption tower is led to an oxidation tower to coarsen the crystals of gypsum, and then led to a centrifugal separator for deliquification. This flue gas desulfurization method is characterized in that the collected gypsum mixed with dust and fly ash is dried and then classified using differences in particle size and specific gravity to extract high-purity gypsum.