Treating waste water, esp. from oil refineries

摘要

Treatment of industrial waste water involves separate storage of the water as surface water and process water (according to the degree of contamination), with integrated removal of coarse solids. The separate streams are then subjected to mechanical oil removal and sepn. of solids. The pretreated process water (with higher degree of chemical contamination) is supplied to a stripping column at 1-6 (pref. 1.4-5) bars absolute and 90-160(pref. 90-150) deg C to drive off hydrogen sulphide and ammonia as vapour and leave a pre-purified water stream as bottom prod. The vapour is supplied to a gas cracking reactor, under the stripping pressure and operated with oxygen at 900-1300 deg C, followed by a cracked gas cooler. The cracked gas (acid gas) is reduced in a hydrogenation reactor and supplied via a combined scrubber and cooler to a drying plant. The pre-purified prod. and the (less chemically contaminated) surface water stream are mixed in an oxidn. reactor operated at 3-6.5 bars absolute. The contents are oxidised by supplying an oxygen/inert gas mixt. and opt. further reactive gases. The water is finally subjected to reduced pressure flotation. Claimed appts. for the process comprises: at least one storage container (A) with integrated sinkage chamber and skimmer; mechanical oil and solids separator (B); solids wash container (C); at least one stripping column (D) and/or at least one oxidn. reactor (K); gas cracking reactor (E) with a cracked gas cooler (F), a hydrogenation reactor (G), a multistage gas scrubber (H) and drying plant (J); and flotation appts. (L) following the oxidn. reactor.