With producer gas it is necessary to pre-heat both the gas and the air which is supplied for its combustion by passing both through heated regenerators (for an account of the principles of the regenerative furnace see article Furnace).
In the position shown in solid lines, these valves deflect the air and gas into the left-hand pair of "regenerators" or spacious heat-transferring chambers.
The products of combustion are sucked by the pull of the chimney through the farther or right-hand end of this chamber, out through the exit ports, as shown by the dotted arrows, down through the right-hand pair of regenerators, heating to perhaps 1300° C. the upper part of the loosely-piled masses of brickwork within them, and thence past the valves K and K' to the chimney, flue 0.
Thence they are sucked out by the chimney-draught through the left-hand ports, down through the uptakes and regenerators, here again meeting ands heating the loose mass of " regenerator " brickwork, and finally escape by the chimney-flue 0.
- Plan through Regenerators, Flues and Reversing Valves..
These regenerators are the essence of the Siemens or " regenerative furnace "; they are heat-traps, catching and storing by their -11, Ton Traver 7s 20 Tan Tra y.
At any given moment one pair of regenerators is storing heat, while the other is restoring it.