Inorganic acid gas treating method and apparatus

Abstract

The present invention relates to a method for treating inorganic acid gas and its equipment. Said method includes the following steps: (a) making inorganic acid gas and an atomized alkaline liquor be formed into a mixture, in which the atomized alkaline liquor can be continuously or intermittently produced; (b) making said mixture pass through a bed body with an adsorbent, in which the adsorbent can be undergone the processes of water-washing, alkaline liquor spraying or soaking treatment; and (c) discharging the treated gas.

Description

technical field [0001] The invention relates to a gas treatment method and device, especially a treatment method and device suitable for inorganic acid gas. Background technique [0002] The semiconductor industry uses a large amount of inorganic acids (mainly hydrochloric acid, hydrofluoric acid, sulfuric acid, and nitric acid) for pickling or etching of wafers, resulting in waste gas and wastewater discharged from the manufacturing process containing inorganic acids, which is prone to environmental pollution. Traditionally, packed wet scrubbers are often used to remove inorganic acid gases. During the gas scrubbing process, a large amount of scrubbing liquid is circulated and sprayed on the packing to produce the effect of gas-liquid contact to remove inorganic acid gases. Although the packed scrubber is generally equipped with a mist eliminator to remove the liquid droplets of the scrubbing tail gas, it is still difficult to avoid the finer liquid droplets being carried o...

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Problems solved by technology

However, since the concentration of inorganic acid pollutants in semiconductor and photoelectric process exhaust is not high, the mass transfer driving force (concentration difference) in the gas phase is not obvious, and it is impossible to generate a large diffusion mass through the concentration difference between the gas phase main body and the gas-liquid interface. Therefore, traditionally, wet scrubbers designed using chemical engineering gas absorption double-membrane theory have poor efficiency when dealing with low-concentration (<10ppmv, especially <5ppmv) inorganic acid exhaust.

[0005] For the treatment of the above-mentioned low-concentration inorganic acid gas, there is currently no better treatment method. Review some technologies that have been developed to avoid the above-mentioned shortcomings of the wet scrubber, such as using wet activated carbon to absorb SO in the hot exhaust gas 2 with HCl, SO adsorbed on activated carbon 2 will be converted to H by its catalysis 2 SO 4 , and then wash it out with water, and the washed H 2 SO 4 After the aqueous solution is concentrated, it is re-injected into the activated carbon bed to replace and drive out the adsorbed HCl, and it is absorbed and washed away by the post-installed wet scrubber and alkaline aqueous solution; in addition, alkali metal hydrogen can also be injected on the activated carbon Oxide or carbonate, after drying at high temperature (120 to 160 ° C), the potassium concentration in the activated carbon can reach 5.9 to 9.4%, so that the SO 2 And HCN has absorbing ability; In addition, there are also technical references to activated carbon containing 20-30wt% calcium that can remove chlorine-containing or sulfur-containing gas in the gas; however, the above-mentioned technologies do not mention low concentrations (<10ppmv, especially It is the treatment method of <5ppmv) inorganic acid gas, and the regeneration method of activated carbon after the adsorption capacity is exhausted

[0006] In the relevant technology of adsorbent regeneration and utilization, there is a device for treating hydrogen sulfide waste gas in sewage field, which uses activated carbon bed impregnated with sodium hydroxide aqueous solution as adsorbent, and the thickness of adsorbent bed is 3ft; however, when activated carbon When the adsorption capacity of the bed is exhausted, it is necessary to use another additional spare activated carbon bed to go online alternately, and at the same time regenerate the adsorption capacity of the activated carbon bed in an offline manner; this technology must be offline for regeneration, which is not conducive to limited land space In addition, since the regeneration operation of the adsorbent bed takes five to fifteen days, and the activated carbon bed of this treatment method can only be regenerated three to four times, the number of regenerations is limited, resulting in a short service life of the adsorbent

[0007] Therefore, there is an urgent need to provide a long-term and stable inorganic acid gas treatment method and device to solve the dilemma of semiconductor and optoelectronic industries dealing with low-concentration inorganic acid exhaust.

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