GB998605A - Improvements in or relating to steam boilers - Google Patents

Abstract

998,605. Regulating steam temperature in boilers. RILEY STOKER CORPORATION. March 13, 1962 [March 16, 1961], No. 9571/62. Heading F4A. In the steam generating unit illustrated control of superheated steam temperature at low loads is effected by preventing the supply of fuel and combustion air to at least one and preferably alternate burners and using this or these burner openings for the introduction of regulated quantities of re-circulated gas. At a suitable value of steam load a control means 49 acts to close a fuel supply valve 111 in the line 109 which feeds the opposed burners 26, 27 located on the lower surfaces of abutments 19, 23 in the front and rear walls of the furnace chamber 17. Simultaneously, slide valves 97, 103 in the combustion air ducts to these burners are closed and slide valves 93, 106 opened allowing re-circulated gas from the ducts 61, 62 to enter the furnace through the burner openings. Adjustable vanes in the burner openings direct the re-circulated gases upwardly to give a blanketing effect and thus to prevent overheating and slagging of the water-tubes. The position of a damper 66 in the re-circulated gas duct 65 is controlled by the control means 49 to regulate the volume of gases re-circulated and thus to regulate the superheated steam temperature. Final control of the superheated steam temperature is effected by a spray desuperheater 116.