Patent GB-284647-A (GB)
Title: Improved method of and apparatus for regulating the density of mixed gases
IPC: F23D14/60
Filed: 1928-01-23
Abstract: 284,647. Smoot Engineering Corporation, (Assignees of Smoot, C. H.). Feb. 2, 1927, [Convention date]. Pressure and vacuum gauges. - Simultaneous flows of the gas to be regulated or metered and of a gas of substantially constant composition are produced and the pressures at predetermined points in such flows utilized to vary the density or indicate the density change the control being adjustable to work on any selected density value. Fans 1, 2 mounted on the shaft 3 of a motor 4 receive gas and air respectively through pipes 5 with restricted inlets 6, the fans exhausting directly to the atmosphere at 7. Radial blades 8 in the fan casings 9 ensure substantially atmospheric pressure at the peripheries of the fans by preventing circumferential flow of the air before exit. Chambers 10, 15 communicate by apertures 12, 17 in rotatable discs 11, 16 with the fan chambers and are connected by pipes 14, 18 to a pressure responsive device 13, the pipe 18 opening into the space above a float 24 while the pipe 14 opens within the float. The discs 11, 16 are mounted on shafts 19, 20 parallel to but slightly out of line with the shaft 3 so that rotation of the discs changes the radial distances of the apertures 12, 17 from the axis of the fans and thus determines the density to which the control works. To the shaft 19 is fixed a lever arm 21 movable by hand over a scale 22. The fan casings 9 are double-walled and water is circulated through them to keep the fans at the same temperature, while the gas and air pass through saturators 47, 48 before reaching the fans so that variations in moisture content of the atmosphere will not affect the apparatus. In operation, the saturator 48 is open to the atmosphere, the saturator 47 connected to the source of gas to be regulated and the lever 21 set to that part of the scale 22 representing the desired density or composition. The capacity of the fans is large relative to the volume of gas and air admitted and the pressure in the fan chambers varies with the square of the distance from the axis of the fan and inversely with the density. Any difference between the pressures at the apertures 12, 17 causes movement of the float 24 to rock a lever 31 and move a valve 42 to vary the leakage of a pressure medium through a port 43 thus varying the pressure in a pipe 56 and actuating any control mechanism for adjusting the composition of the gas. A scale 46 opposite the lever 31 shows the variation in density, and means may be provided to cause movement of the lever 31 to control the position of the arm 21 to indicate the density of the scale 22. The float 24 has a central hollow portion 26 extending downwardly and closed at the end 27 but open to the liquid through apertures 28. A fixed tube 29 open to the atmosphere extends into the cylinder 26 and a tube 30 attached to the closure 27 extends through the tube 29 and serves to transmit the motion of the float to the lever 31. Within the float 24 is an open vessel 34 carried by the portion 26 and having in its base a leakage port 36 the opening of which is controlled by a screw 37. When the float moves in either direction a temporary difference in the level of liquid within and without the vessel 34 occurs which offers opposition to further movement of the float, for a time depending on the leakage through the port 36. The float is counterbalanced by an adjustable weight 45 on the lever 31. Fig. 3 shows the apparatus used for controlling the ratio of air to fuel feed in a boiler furnace 58, pipes 50 supplying the combustion gases to the saturator 48 and the pipe 56 leading to a diaphragm chamber 67 connected to a lever 64 fulcrummed at 65 and connected at its other end to a diaphragm chamber 66 in communication with the air supply conduit of the furnace. Movement of the lever 64 due to variations of the fluid pressure in the pipe 56 is transmitted through levers 71 - - 74 to a valve 60 in the air supply conduit 61 of the furnace. In use with a system of centralized regulation such as that of Specification 179,953, [Class 51 (i), Furnaces and kilns, Combustion apparatus of], the pipe 63 would transmit air pressure from a master controller.