GB1089922A - Steam generating unit - Google Patents

Abstract

1,089,922. Fluid-pressure servomotor systems. RILEY STOKER CORPORATION. Feb.16, 1965 [Feb. 25, 1964], No. 6627/65. Heading G3P. [Also in Division F4] A steam generator having eight burners 24, 25 and 62-67 is provided with a control system which maintains the air-fuel ratio at each burner at a predetermined value. The burners are arranged in two banks of four and each bank receives a fuel supply from a main line 75 via a main fuel valve 76. A valve 79 controls the amount of fuel passing to each bank, and valves 84, 97 divide the flow to each bank into two lines, each line serving a pair of adjacent burners in a bank. Further valves 88, 93, 102 and 106 divide the flow to each pair of burners into two further lines which serve individual burners. Air is supplied to each burner from a main supply duct containing a Venturi 41 Fig. 1 (not shown). The air-fuel ratio at each burner is determined by relays 113, 118, 121, 123, 125, 127, 129 and 132 which utilize orifices 51 and 109 provided in the air and fuel supply passages respectively. The output signals from the relays are representative of the respective air-fuel ratio 8, and these signals are received by a main controller 61 Fig. 3 (not shown). Output signals from the main controller actuate the valves 79, 84, 88, 93, 97, 102, 106. In operation, signals from the Venturi in the main air duct actuate a relay 44 which in turn actuates a solenoid-operated pilot valve 139 via a servomotor 135 and a rheostat 136. The pilot valve 139 controls a servomotor 141 connected to the main fuel valve 76. The signals from the pair of relays 113, 118 associated with burners 25, 62 are compared in a relay 153 (Fig. 3) and the output signal from this latter relay controls valve 88 via a servomotor 155, rheostat 156, pilot valve 157 and servomotor 89. Similarly, each of the valves 93, 102 and 106 is controlled by signals from the pair of relays associated with the pair of burners which the valve serves. A further relay 158 in the main controller compares the signals from relays 113, 118 with those from relays 121, 123 and actuates valve 84 via servomotor 161, rheostat 162, pilot valve 163 and servomotor 85. Similarly, valve 97 is actuated by a relay 164 which compares the signals from relays 125, 127 with those from relays 129, 132. Valve 79 is actuated by a relay 143 which compares the signals from relays 113, 118, 121, 123 with those from relays 125, 127, 129, 132, actuation of the valve being via servomotor 144, rheostat 145, pilot valve 146 and servomotor 81. The fuel may be gaseous, liquid or pulverulent. In the modification of Fig. 4 (not shown), the air flow to each burner is measured by means of a Venturi.