Patent GB-899850-A (GB)
Title: Improvements in vapour generating units
IPC: F28D7/00
Filed: 1961-04-18
Abstract: 899,850. Gas-fired steam generators. BABCOCK & WILCOX CO. April 18, 1961 [April 22, 1960], No. 13934/61. Class 51 (1). A vapour generating unit comprises a horizontal furnace chamber extending lengthwise from a front wall, and containing a burner supplying high calorific value fuel and combustion air to the furnace chamber, and in the front and one side wall are ports to supply gaseous fuel of low calorific value, arranged so that the high and low calorific value fuels are combusted together. The furnace chamber 10, Fig. 3, has side walls 11, 12 lined with generating tubes 15, 16, and a front wall 13 lined with refractorycovered tubes. In the side wall 11 is an outlet 29 leading into a convection gas pass 20, which leads in turn into an economizer section 22 beneath a flue 23. In the front wall is a centrally-spaced burner port 24 accommodating an oil burner 25, an air register and for initial ignition, an igniter tube 27. Above and below the burner port, respectively, are low calorific value fuel gas ports 30, 31 and 32, 33, Fig. 2 (not shown), arranged in a square. In a side wall 12, and close to the front wall, are additional low calorific value fuel gas ports 34, 35 in openings 19, 19A, the ports consisting of refractory lined rectangular metal nozzles 36, 37 inclined at 75 degrees to the side wall towards the end wall 14. The level of ports 34 is between the upper set of ports 30, 31 and the burner port 25, and the port 35 is similarly arranged between ports 32, 33 and burner 25. The lead-in duct 40 for the low calorific value fuel gas from a catalytic regenerator kiln connects through a T-pipe 41 leading into cylindrical water-seal tanks 44, 45. The duct 46 leads directly to the flue 23, whereas duct 47 is extended into a gas chamber 54 enclosing the gas ports 34, 35. Ducts 55, 56 pass from the top and bottom of the gas chamber 54 to gas ports 30, 31 and 32, 33, respectively. Two blowers 60, 61 discharge into an air housing 64 on the front wall 13 which encloses the burner port 24 and also the gas ports 30-33, although supplying air only to the burner port. From the air housing 64 a duct 65 leads to a tube 66 from which tubes 67, 68 with dampers 67A, 68A lead to air pipes, 70, 71, which extend through the gas ports 34, 35, and which contain oil atomizer assemblies 72, 73, Fig. 2 (not shown). A duct 74 links the top of tube 66 to the extension of tube 47. Operation.-The furnace may be run on fuel oil from burner 25 alone, when the seal tanks 44, 45 are filled with water to close off the ducts 46, 47, dampers 67A, 68A are closed, and damper 75 is opened. Fans 60, 61 pass air to the air housing 64, most of which passes through an air register, surrounding the oil burner 25, although some passes through duct 74 to the chamber 54 where it is discharged through ports 30-35. When the furnace is to be run on a combination of fuel, the low calorific value fuel gases are reduced to a pressure of about one pound per square inch above atmospheric, and are passed through duct 40 into tanks 44, 45. The water level in tank 45 is lowered so that the gases may flow into the gas chamber 54, with damper 75 closed, whence they enter the furnace chamber 10, with half of the total volume passing through ports 30-33 and half through ports 34, 35. Air is discharged into the furnace chamber through air pipes 70, 71, and further fuel may be supplied through the oil atomizer assemblies 72, 73, the combustion air for which is adjusted by dampers 67A, 68A so that any additional air required to consume the carbon monoxide content of the low calorific value fuel gas is discharged through these assemblies. When the furnace operates on a combination of fuel, only one fan is needed.