Patent Number: 039727726
Section: description

Referring now to the drawing, blowdown water which is produced in the steam generators due to an accumulation of existing impurities conducted to a purifying device 4, 6 is from a non-illustrated blowdown tank as well as a brine cooler through a line 1, in which a measuring orifice 2 and a shut-off valve 3 are connected. The invention of this application is based on the realization that the impurities are formed mainly of iron oxides and salts, so that an electromagnetic precipitation or deposition device in combination with a mixed bed filter is considered basically to be adequate for effecting reclamation of the water. Accordingly, the blowdown is delivered to the electromagnetic filter 4 and emerges therefrom free of ferritic impurities, through line 5. The electromagnetic filter 4 operates in the following manner. The quantities of water to be purified traverse a hollow space which is partly or nearly completely filled with hard-magnetic steel balls, a strong magnetization of the steel balls, preferably far exceeding the magnetic saturation, thereof being produced by relatively high excitation currents, so that the magnetizable impurities then adhere to the hard magnetic balls. From time to time, a rinsing or regeneration of the electromagnetic filter becomes necessary; during the rinsing process, chopped or intermittent direct current of decreasing and alternately opposing polarity, may be used for de-excitation of the filter and, at the same time, rinsing water can be supplied under such pressure and in such quantities that the steel balls are whirled upwardly and perform a dancing motion. From the electromagnetic filter 4, the blowdown is passed through the line 5 to the mixed bed filter 6, the thus purified water being conducted through line 16 and 7 into the machine condenser or into the condensate line or string and thereby returned to the circulatory system of the power plant. If the water mainly contains oxidic impurities, the recycling can be effected by by-passing the mixed bed filter 6, with the shut-off valve 8 closed and the shut-off valve 9 open, through the by-pass 10, a relief valve 11 and a three-way valve 12, as well as through the line 7. On the other hand, ionogenic impurities are removed through the mixed bed filter 6, downstream of which a resin catcher or capturing device 13 is connectible for safety reasons. The rinsing and regeneration of the electromagnetic filter 4 can be effected by means of the water brought in from the non-illustrated brine cooler through the line 1. The mixed bed filter 6 can be regenerated, as indicated diagrammatically by a line 14, with caustic soda solution and, furthermore, as indicated diagrammatically by a line 15, with hydrochloric acid or with sulfuric acid. The lines 14 and 15 are brought in from the water-preparation plant. The rinsing and regenerating waters can be discharged to a non-illustrated neutralizing tank through line 18 from outlet line 16, when the valve 17 is opened. When leakages occur between the primary and the secondary circulatory systems, the discharge of these waters is effected through the line 20 to the waste water preparation installation by opening the valve 19. From the three-way valve 12, a line 21 leads to a main cooling water outlet (not shown).