GB999617A - Improvements relating to steam generating plant - Google Patents

Abstract

999,617. Feedwater supply systems for steam boilers. WAAGNER-BIRO A.G. Jan. 22, 1962 [Jan. 20, 1961 (3)], No. 2194/62. Heading F4A. In a method of generating steam wherein a waste heat boiler utilizes the intermittently available waste heat of a metallurgical or chemical process, steam or hot water from the boiler is supplied to one or more secondary drums during the process periods to provide either a supply of hot feed-water or to heat a heat retaining liquid in the drum(s) and in the process intervals hot feed-water obtained either directly from the drum(s) or by passing feed-water in heat exchange with the hot heatretaining liquid is fed to the boiler. As shown in Fig. 3 water from a boiler drum 3 is withdrawn by pumps 11, heated at 1 and returned to the drum, steam being withdrawn from the drum through line 13 and feed-water being supplied to the drum via an economizer 2 through a line 6. The boiler is associated with a converter and during blowing periods of the latter hot water from drum 7a is passed through a line 7a to a secondary drum 4 containing a float 25 and a volume 18 of cold water beneath the float. The float is thus displaced downwardly and cold water from drum 4 is supplied to drum 3 through line 7b. During the blowing interval of the converter feed-water is supplied through line 7 to the bottom of drum 4 to force the hot water 17 stored above float 25 into the drum 3 through line 7a and thus to minimize the additional heating necessary to maintain the steam supply. The line 7b may communicate with the inlet side of pumps 11 rather than with drum 3 (Fig. 4, not shown) and the steam from line 13 may be passed through a superheater (Fig. 5, not shown). In the embodiment of Fig. 6 steam from line 13 is passed to drum 4 during the blowing period to form a supply of hot water 17 and a steam cushion 19 above the float 25. Feed water from a pump 10 is fed partly to a mixing valve 9 and partly to the bottom of drum 4 through line 7, and hot water from drum 4 is supplied to valve 9 via a take-off pipe supported by float 25 and line 7a. The relative proportions of hot and cold water supplied to mixing valve 9 are controlled through control lines 22 responsive to the water level in drum 3. A circulating line 15 with a pump 12 is provided for circulating the water in the drum 4. A superheater may be provided in line 13 for heating either all of the steam produced in the boiler or only that part of the steam which is supplied to the consumer. In the embodiment of Fig. 12 surplus steam is passed through a line 14 to the central one of three heat exchange coils 16 in drum 4 so that the steam gives up its heat to a liquid 20, e.g. glycerine, oil or mercury, in the drum, the condensed steam being collected in a receiver 4a in the feed water inlet line 33. In the process intervals feed water is fed through the two remaining coils 16 to be heated by the liquid 20 before passing to drum 3. In a further embodiment (Fig. 11, not shown), the two feedwater coils are omitted and the drum 4 merely contains feed-water.