GB1289064A - - Google Patents

Abstract

1289064 Demineralization of water EL PASO NATURAL GAS CO 22 March 1971 7432/71 Heading B1B Water which contains minerals, such as well water or saline water, is subjected to distillation, ion exchange, reverse osmosis or electrodialysis to obtain demineralized water and a water-fraction which is concentrated in mineral content, this concentrated fraction is mixed with a relatively non-volatile liquid, e.g. a fuel oil or a silicone oil, and the mixture is heated to evaporate all the water leaving a slurry of solids (mineral particles) in the non-volatile liquid; the water-vapour is condensed to obtain demineralized water, and the solids are separated, e.g. by centrifuge, from the non- volatile liquid which is then re-used in the process. The solids may be used as a fertilizer or for chemical recovery; or they may be disposed of in a lined pit. Sewage and other waste water may be disposed of in the dehydration stage of the process. The Fig. shows an evaporator 340 for dehydrating the mixture of water and non-volatile liquid, associated with plant for the removal of acidic components (H 2 S and CO 2 ) from natural gas. The sour gas is introduced through line 314 into the lower section of tower 310 and is contacted therein with a countercurrent stream of an absorption solution, such as alkanolamine, introduced through line 338. The purified gas leaves the top of tower, 310; and the contaminated solution, withdrawn from the base, is passed through heat exchanger 320 into stripper 312 where it is heated to drive off the acidic components. Stripper 312 is heated by steam from generator 376 which is supplied with dimineralized water from a multi-stage vacuum distillation unit (not shown) for separating the raw feedwater into two fractions. The regenerated absorption solution is returned to tower 310 through heat exchangers 328, 320 and 332. In heat exchanger 328, the solution is cooled by a heat-exchange medium which transfers heat to the heating unit 346 in evaporator 340. Some of the demineralized water obtained from evaporator 340 is circulated through heat exchanger 332 and cooling tower 360. Any purge water necessary from this circulating system is passed through line 368 to evaporator 340. Purge water from steam generator 376 is also passed to evaporator 340. A petrochemical plant (Fig. 5, not shown) is described wherein polluted air is purified by contact with demineralized water. The clean air is discharged to the atmosphere; and volatile components are separated from the wash water in a multi-stage flash evaporator.