| 摘要 |
<p>1,36,826. Filtering gases. NATIONAL LEAD CO. May 15,1964 [May 15, 1963], No. 20453/64. Heading B1R. A method of treating gases which contain solid aerosols alone or mixed with liquid aerosols and/ or undesirable gaseous components comprises passing the gases through at least one filter of hydro phobic fibres into which, in a direction concusent with the gas flow, is directed a flushing liquid which is non-solvent for the solid aerosols but at least a partial solvent for the undesirable gases, collecting the solid-aerosol-burdened liquid on the downstream side of the filter and discharging the treated gases separately; the filter or the first filter has a thickness of not more than 0. 2 inches. The method may be applied to the effluent gas of the calcination of titanium dioxide hydrate, which gas contains oxides of sulphur, water, sulphuric acid and entrained sub-micron particles of titanium dioxide, the flushing liquid used being water, a weak acid or an aqueous TiO2 slurry. The filters, which may be in the form of flat pads or candles, may be silicone-treated glass wool or preferably a syn-. thetic polyester fibre e.g. "Dacron" (Registered Trade Mark) (polyethylene terephthalate) or "Terylene", (Registered Trade Mark) of which the fibrous diameter is preferably less than 30 Á; the filter or the first stage filter may be 0. 05 and 0. 2 inches thick with a bulk density in the range 2. 0-10. 0 lbs. /cu. ft. While its constituent fibres have a density of 1. 4-1. 5 g per ml. Two filters in series may be used, the first only being flushed, and the flushing liquid being continuously recovered and recycled. In the Figure the gas to be treated and the flushing liquid are directed through inlets 13, 14 respectively on to first filter 16, spent liquid being withdrawn at 15; solid-free gas leaving 16 passes through second filter 17, depositing residual liquid aerosols therein, and is recovered at 19, the liquid residues being removed at 20.</p> |
