JPS6238738Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus that efficiently removes hydrogen chloride (HCl) contained in incinerator exhaust gas.

The exhaust gas from incinerators, especially incinerators for industrial and household waste, contains high concentrations of HCl derived from organic chlorine compounds such as polyvinyl chloride, and it is important to prevent secondary pollution. Therefore, equipment to remove these is necessary.

An alkaline HCl absorbent is generally used to remove HCl from exhaust gas, and there are three main methods for removing HCl: dry, wet, and semi-wet.

In the dry removal method, a powdered HCl absorbent is sprayed into exhaust gas to cause a gas-solid reaction with HCl, and the reaction product is recovered as a powder. As HCl absorbents, inexpensive calcium-based limestone (CaCO ₃ ), slaked lime (Ca(OH) ₂ ), and quicklime (CaO) are often used. Since this is a gas-solid reaction, the particle size and surface condition of the sprayed absorbent greatly affect the reaction.In general, the removal rate is poor unless the injection equivalent ratio to HCl is increased, and in the case of a garbage incinerator, Ca In order to control HCl to 430ppm or less with (OH) ₂ , it is usually necessary to inject 3 equivalents or more per inflowing HCl, and it is difficult to control the injection amount for powders compared to liquids, so it is difficult to control the injection amount by setting excessive injection. I had no choice but to colander.

In addition, the wet removal method cleans the exhaust gas with an HCl absorbing liquid in which an HCl absorbent is dissolved or suspended. In this method, sodium-based absorbents are generally used extensively, but calcium-based absorbents with low solubility are used as a suspension, which prevents the suspended absorbent from accumulating in the gas scrubbing tower or cleaning fluid circulation system. Maintenance of the device is difficult because it is stuck and fixed. However, even when a sodium-based absorbent is used, the unit price is high, resulting in relatively high running costs, and problems such as scale precipitation on areas in contact with the cleaning liquid occur. In addition, the cleaning fluid requires addition of absorbent and partial renewal of the fluid, which necessitates drainage treatment.Furthermore, the cleaned exhaust gas is usually supercooled to several tens of degrees, so it passes through the chimney into the atmosphere. It must be reheated to prevent white smoke before being dissipated, and the initial cost of the equipment is much higher than in the dry removal method described above.

In addition, as a third HCl removal method, a liquid in which an HCl absorbent is dissolved or suspended is sprayed into the exhaust gas.
There is a so-called semi-wet removal method in which droplets are evaporated to dryness using the heat of exhaust gas and recovered as powder.
This method has the advantage of being able to remove HCl more efficiently than the dry method without requiring many incidental facilities (e.g., wastewater treatment, white smoke prevention, etc.) like the wet method.
In order to improve the HCl removal rate and reduce the injection equivalent ratio, it is necessary to reduce the concentration of the absorbent to the lowest possible level and spray it into the exhaust gas as fine water droplets. However, spraying at low concentrations requires extensive dissolution and suspension equipment and supply equipment. Also, cheap Ca
When (OH) ₂ is used as an absorbent, due to its low solubility in water (approximately 1.7 Kg/m ³ for Ca(OH) ₂ ),
It has to be sprayed as a suspension, but suspended particles
When water droplets evaporate to dryness before reacting with HCl, Ca
(OH) ₂ Since the pores on the surface of the particles are blocked,
On the contrary, reactivity worsens.

The present invention aims to eliminate the drawbacks of conventional HCl removal devices, and to provide a device that can efficiently remove HCl from incinerator exhaust gas with ease of operation.

The present invention includes: supply pump equipment for supplying water to an injection nozzle installed in a gas cooling chamber for incinerator exhaust gas; equipment for dissolving and suspending an HCl absorbent to obtain an HCl absorption liquid; and supply pump equipment for the HCl absorption liquid. , dilution equipment for diluting the HCl absorbent with water supplied to the injection nozzle, means for guiding the diluted HCl absorbent to the injection nozzle, HCl absorbent flowing out from the gas cooling chamber;
Dust removal equipment for removing HCl reaction products.

Further, one embodiment of the present invention will be described with reference to the drawings. A is an incinerator, which is connected to a gas cooling chamber C by a flue B through which generated high-temperature exhaust gas flows. The gas cooling chamber C is equipped with an injection nozzle 1, and the outlet of the gas cooling chamber C is equipped with dust removal equipment D such as an electric precipitator or a multi-cyclone. It is connected to a chimney.

Reference numeral E denotes a supply pump equipment for the gas cooling water 3, which is equipped with, for example, a flow rate regulating valve 4, and is connected to the header pipe 5 of the injection nozzle 1 via a dilution equipment F such as a line mixer. Further, G is a dissolving/suspending equipment for mixing the HCl absorbent 6 and water 7 to obtain an HCl absorbing liquid 8, and G is a dissolving and suspending equipment for mixing the HCl absorbing agent 6 and water 7 to obtain an HCl absorbing liquid 8. The dilution equipment F
It is connected to.

The high temperature exhaust gas containing HCl generated in the incinerator A passes through the flue B and is cooled to a predetermined temperature by the supply pump equipment E injecting gas cooling water 3 from the injection nozzle 1 in the gas cooling chamber C. Water 7 is added to the HCl absorbent 6 for removing HCl in the exhaust gas in the dissolution/suspension equipment G, and the HCl absorbent 8 is stored as a solution or suspension. This HCl
As the absorbent 6, sodium-based alkaline components such as NaOH and Na ₂ CO ₃ and calcium-based alkaline components such as Ca(OH) ₂ and CaO are used, and the concentration is 5.
Add 7 parts water to ~20%. Note that calcium-based components have low solubility in water, so
Constant stirring is required to store it in a suspended state.

The HCl absorption liquid 8 in the dissolution and suspension equipment G is:
It is mixed with the gas cooling water 3 injected in the gas cooling chamber C at the dilution facility F through the supply pump equipment H and the flow rate adjustment valve 9 to become further diluted, and then flows from the injection nozzle 1 to the gas cooling chamber C via the header pipe 5. The HCl and HCl absorbent react with each other, and the droplets evaporate and solidify due to the heat of the exhaust gas.The reaction product becomes powder and is collected by dust removal equipment D along with the outflowing gas flow. be done. Further, coarse particles in the gas cooling chamber C are taken out from the lower part of the gas cooling chamber C, and are reused as the HCl absorbent 6 as the case may be.

Note that the inlet temperature of dust removal equipment D is a constant value (250~
In order to control the supply amount of gas cooling water 3 so that the temperature is 350℃), the inlet temperature and flow rate adjustment valve 4 of dust removal equipment D are
or by associating the pump with the automatic control circuit 10 and measuring the HCl concentration in the exhaust gas, for example, the HCl concentration at the exit of the dust removal equipment D or the flue B,
It is convenient to provide an automatic control circuit 11 that controls the flow rate of the HCl absorbing liquid 8 with a chemical equivalence ratio sufficient to remove it to a set value or regulation value using a flow rate regulating valve 9 or a pump.

In addition, the supply amount of HCl absorption liquid 8 is determined by the amount of HCl in the exhaust gas.
In order to follow the concentration fluctuations, it is necessary to consider the mixing point of the gas cooling water 3 and the HCl absorbing liquid 8 so that the liquid retention time from the dilution equipment F to the injection nozzle 1 is the shortest. By providing a control system that subtracts the supply amount of gas cooling water 3 from the supply amount of gas cooling water 3, the temperature at the inlet of the dust removal equipment D can be controlled more accurately.

As described above, according to the present invention, the following remarkable effects can be obtained. Since the amount of water injected for cooling the high-temperature exhaust gas can all be used for dissolving and suspending the HCl absorbent, the absorbent concentration can be diluted to the maximum. For this reason, not only sodium-based absorbents but also calcium-based absorbents with low solubility have a high HCl removal rate.
The blowing equivalent ratio can be reduced compared to the conventional semi-wet method, and the advantages of the conventional semi-wet method (simple equipment, easy operation, easy collection of reaction products)
There is no harm to it.

Since the HCl absorbent can be diluted to the maximum extent possible, problems such as blockage of the injection nozzle, scale formation on piping and nozzle tips, and adhesion of reaction products can be eliminated.

It can also be easily applied to incinerators with existing water injection gas cooling devices.

[Brief explanation of the drawing]

The drawing is a layout diagram showing an embodiment of the present invention. A... Incinerator, B... Flue, C... Gas cooling room, D... Dust removal equipment, E, H... Supply pump equipment, F... Dilution equipment, G... Dissolution suspension equipment, 1...
...Injection nozzle, 2...Induced blower, 3...Gas cooling water, 4, 9...Valve, 5...Header pipe, 6...
HCl absorbent, 7...water, 8...HCl absorbent.

Claims (1)

[Claims for Utility Model Registration] 1. Supply pump equipment for supplying water to the injection nozzle provided in the gas cooling chamber for incinerator exhaust gas, hydrogen chloride absorbent dissolution and suspension equipment for obtaining hydrogen chloride absorption liquid, and the above-mentioned supply pump equipment for hydrogen chloride absorption liquid, dilution equipment for diluting the hydrogen chloride absorption liquid with water supplied to the injection nozzle, means for guiding the diluted hydrogen chloride absorption liquid to the injection nozzle, and the gas cooling chamber. 1. An apparatus for removing hydrogen chloride from incinerator exhaust gas, comprising a hydrogen chloride absorbent flowing out from the incinerator and dust removal equipment for removing reaction products of hydrogen chloride. 2. The scope of the utility model registration claim, wherein the supply pump equipment for supplying water to the injection nozzle is equipped with a flow rate regulating valve, and the amount of water by the valve or pump is controlled by the temperature at the inlet of the dust removal equipment. The hydrogen chloride removal device for incinerator exhaust gas according to item 1. 3. The supply pump equipment for the hydrogen chloride absorption liquid is equipped with a flow rate regulating valve, and the flow rate of the absorption liquid by the valve or pump is controlled by the hydrogen chloride concentration at the inlet of the gas cooling chamber or the outlet of the dust removal equipment. An apparatus for removing hydrogen chloride from incinerator exhaust gas according to claim 1 or 2 of the utility model registration claim.