GB1334979A - Furnaces - Google Patents

Abstract

1334979 Gas fired furnaces KOPPERSWISTRA-OFENBAU GmbH 3 May 1972 20647/72 Heading F4B In a furnace having burners arranged in groups, one group forming an eddy with a different direction of rotation from that formed by another group, as described in Specification 1,282,231, the control means is such that all the burners are operated together for the full rated heat output, for a heat output between 50 and 99% of full value burners of one group are operated for periods alternating with periods in which all burners are operating and for a heat output less than 50% of the rated value, burners of a group are switched on and off, and except when all the burners are operating, the groups of burners are operated in turn to repeatedly reverse the direction of rotation of the hot gases. Each burner group may be divided into sub-groups, and one or more of the sub groups may be switched off to regulate the heat input. In the furnace of Fig. 5, burners 7, 9, 11 form one group, and burners 8, 10, 12 form another group, and for low heat outputs, each sub-group 7, 9, 11 of one burner group is switched on and off during one sixth of a heating cycle, the other sub groups remaining on or off for this period according to the desired heat output, and the burners 8, 10, 12 of the other group being switched off. After half the heating cycle, all the burners 7, 9, 11 are switched off, and the subgroups 8, 10, 12 are, in turn, switched on and off to give a fire regulation of the heat output during one sixth of a cycle, the remaining sub groups being switched on or off according to the heat required.