GB340295A - Improvements relating to steam generating systems and apparatus - Google Patents

Abstract

340,295. Indirectly heated steam boilers. BAUMANN, K., North woodhouse, Barnfield, Urmston, Lancashire. Aug. 21, 1929, Nos. 25503/29, 34957/29, 34958/29, 34959/29, and 10343/30. [Classes 123 (ii) and 123 (iii).] Steam from water-tube boilers having one or more separate evaporators is passed through a succession of superheater elements and heating elements alternating therewith arranged in the water space of the boiler drum or drums and in one or more evaporators or in the evaporators only. In the plant shown in Fig. 1, steam from the boiler drum 2 passes together with steam from evaporators 4, 5, 6, alternately through superheaters 7, 9, 11, 13 and heating elements 8, 10, 12 in the evaporators, the finally superheated steam being led to a steam consumer 14. The superheater elements may be arranged in counterflow to the direction of the furnace gases or in parallel flow: thus steam may pass through the first element in a counterflow and the second in parallel flow (Fig. 11). Several nests of heating elements may be contained in a common drum. An evaporator may constitute a separator for the boiler drum. One or more evaporators may receive feedwater from sources different from that supplying the boiler ; in one arrangement the drum and evaporators which may not be connected on the water side may receive feed alternatively from two sources. The boiler tubes may line the furnace walls as shown in Fig. 11, and the roof tubes may be finned or covered with refractory material at the parts 35, 54 as a protection of a superheater chamber 34 and the drum 33 against the furnace heat and their intermediate parts 36 staggered to allow ingress of furnace gases into the superheater chamber. In this construction the evaporator or evaporators 57 comprise vertical cylinders with hairpin heating elements 58. The water spaces in boiler drum and evaporator are connected and the level controlled by means of a throttle valve in a connecting steam pipe 40. The water level may be varied to control the heat given up by the heating elements 58 and thus the final temperature of outgoing steam. This may also be controlled by means of a valve-controlled byepass 63 between the inlet and outlet chambers of the heating elements.