Abstract: The presence of the oxides of nitrogen in the exhaust gas leaving a regenerator is limited by injecting water or water vapor into the regenerator 1 during its firing phase and causing the water or water vapor to reach the combustion chamber 26 of the regenerator 1 by way its heat storage bed 11 which has been preheated during a previous heat collecting phase.

Abstract: Silicon containing methanation catalysts e.g. those prepared by coprecipitation techniques, may be stabilized to prevent leaching of silicon species by a hydrothermal treatment comprising heating the reduced catalyst in a steam reducing gas atmosphere, lowering the temperature until liquid water species condense out, reheating to evaporate the condensed water and passivation in a mildly oxidizing atmosphere.

Abstract: Apparatus is provided for the flow control of the flue gas to combustion air ratio in a reversible regenerative heating system of the type comprising a pair of regenerators, a first line 7 for supplying air to the regenerators, a second line 8 for removing flue gas from the regenerators, and valves 9,10 respectively for controlling the flow rate of air in the first line 7 and the flow rate of the flue gas in the second line 8. The apparatus comprises a third line 21 adapted to provide a slave flow of fluid proportional to the flow rate of the flue gas, thermistor type anemometers 17 and 18 for sensing the flow rates of combustion air and fluid and a ratio controller 24 for adjusting the flue gas damper valve 10 in accordance with the flow rates so sensed to maintain the ratio of the flue gas to combustion air at a predetermined ratio.

Abstract: A recuperative burner comprises an outer annular two part duct 13 and 14 for supplying combustion air to four axially aligned chambers 15 located radially inwardly of the ducts 13 within the annular space between the duct 14 and a central fuel pipe 23. The combustion air enters the burner by way of an inlet 9 before entering the outermost duct 14. The air then travels along the innermost duct 13 and enters each chamber 15 by way of an inlet 20. The air then flows forwardly along each chamber 15 before leaving the chamber 15 by way of an outlet 21 before mixing with the fuel leaving a nozzle 24 at the outlet end of the fuel pipe. Waste gas flows in the spaces 22 between the chambers 15 in a direction opposite to the direction of air flow in the chambers 15 before leaving the burner 1 by way of an outlet 11. Heat from the waste gas is transferred to the air flowing in each chamber 15 and to the air flowing in the annular duct 14.

Abstract: A pulse-fired burner is operated by modulating a fuel supply rate between a pilot level and a main level to provide a flame the level of which modulates respectively between a pilot level during a non-firing phase and a main flame level during a firing phase. Air supplied at a pilot rate is premixed with the fuel before ignition, the pilot air level being sufficient to support combustion of the fuel at the pilot rate but not at the main rate. The supply of fuel is terminated if no flame is sensed.

Abstract: The system is particularly suitable for controlling a solenoid valve SV1 having two stable operating positions in accordance with programmed `on` and `off` periods set at a 24 hour timer 10. The valve typically in one position connects a gas supply to a regulator ensuring the latter then supplies gas at a higher pressure; and in the other position connects the regulator to atmosphere through a vent stack so that the regulator then supplies gas at a lower pressure. The system is powered by 3 volt batteries B1, B2 and has extremely lower current consumption giving a battery life of 5-6 years. The solenoid 18 is energised briefly by voltage pulses fed from a capacitor C5 via a reversing switch 16. Automatic battery voltage checking is incorporated.

Abstract: The regenerative heating apparatus (FIG. 1) comprises a pair of regenerators 51a and 51b arranged so that in use while one is being heated by waste gas, the other is preheating air for the combustion of fuel. A reversing valve 58 is connected to each lower end 91a and 91b of the regenerators 51a and 51b, the valve 58 connecting the regenerators 51a and 51b to an inlet 99 for receiving air and an outlet 100 for discharge of the waste gas. The reversing valve 58 is reversible to connect one regenerator to the inlet and the other regenerator to the outlet. Each regenerator incorporates at its upper end a burner (B1 and B2) with as shown in FIG. 2 a body having a passage 2 formed with openings 3 and 4. The opening 4 serves to receive air for combustion when its regenerator is preheating air or to discharge waste gas to the regenerator while the opening 3 serves to supply combusted fuel and air to the furnace 90 or to receive waste gas from the furnace 90.