Patent GB-311195-A (GB)
Title: Improvements relating to steam generators
IPC: F23N1/02
Filed: 1928-01-05
Abstract: 311.195. Gordon & Co., Ltd., J., and Peebles, T. A. Jan. 5, 1928. Regulating combustion.-A control system for a number of boiler furnaces comprises a master regulator responsive to the condition of steam in a common steam header, a primary regulator to each boiler responsive to the master regulator, and fuel and air regulators each responsive partly to the primary regulator and partly to selected conditions existing within the furnace, the feature of responsiveness to local conditions being superimposed on regulators which are themselves stable in any setting according to the steam condition. The various regulators mav be freed from automatic control and operated by hand. The master regulator 6 may be similar to that described in Specification 172,415 and comprises a pressure chamber 8 connected by a pipe 12 to the steam line fed by the group of boilers, one boiler 29 fired by pulverulent fuel being shown. Variations of steam pressure move a lever 9 to control the operation of fluid-pressure relay mechanism 11 connected by a lever 11<a> to a bell 13 partially immersed in liquid in a receptacle 13a. Air is delivered to the interior of the bell by a pipe 13b under a pressure higher than can be sealed by the bell in any position, so that there will be leakage of air around the lower edge of the bell and the pressure within the bell will vary according to its depth of immersion. This pressure is transmitted by pipes 14 to the primary regulators 7, Fig. 3, of the various boilers, which may be similar to the regulator described in Specification 170,683 and comprise two bells 7a, 7<b> mounted on a pivoted lever 7f, the bells being immersed in liquid in a receptacle 7<c>. A branch 14a of the piping 14 projects into the interior of the bell 7a while the bell 7<b> is open to the atmosphere through a valve-controlled pipe 7<e> so that the bell 7<b> serves as a dash-pot. An adjustable spring 18 is connected between an extension 19 of the lever 7<b> and the liquid receptacle 7<c>. A relay 20 making incremental movements in response to movements of the lever 7<a> adjusts the rheostat 21 of a reversing motor 22b controlling supply of current to coal feeding motors 22. The relay 20 is also directly connected to a damper 23 controlling the supply of secondary air to the burner 24. A flexible tube 62a filled with mercury is carried by the relay 20 and connected to the pressure chamber 8<a> of stable relay mechanism 25 similar to the primary regulator 6 and comprising a lever 9<a> controlling a frame 25a operating the flue damper 26. A pipe 27 open to the flue 28 is connected with the interior of a liquid-sealed ,bell 25b suspended from the lever 9<a> to modify the operation of the regulator 25 in accordance with the pressure in the flue. The relay 20 is also connected to a lever 30 from which is suspended a liquid-sealed bell 30<a> supplied with air by a branch 13<c> of the piping 13b. Pipes 31, 31<b> transmit the pressure within the bell 30<a> to one compartment of a double bell 41<a>, Fig. 1<a>, in a regulator 41 for the induced draught fan 40. The other compartment of the double bell communicates by a pipe 42 with the intake of the fan 40, and the double bell is balanced by a bell 41b open to the atmosphere through a restricted passage 41<c>. To regulate the air supply fan 33 a branch 31<a> of the pipe 31 transmits the pressure within the bell 30<a> to the bell 32b of a regulator 32, this bell being balanced by a bell 32<c> connected by a pipe 33a with the air supply pipe 36 on the furnace side of the preheater 35. The supply of secondary air through ports 29<a> in the furnace wall is controlled by a damper 37 actuated by a regulator 38 responsive solely to the pressure within the furnace by a pipe 39. The air for conveying the pulverulent fuel is delivered by a fan 48 to a common duct 47, the fan regulator 49 being responsive directly to the master regulator through a branch 14<b> of the pipe 14, and also to the pressure in the duct 47 by a pipe 49<c>. From the duct 47 the air passes to a duct 46 for each boiler furnace, the delivery being proportioned to the rate of fuel delivery to that furnace by connected valves 52 governed by a regulator 51 responsive to the primary regulator through a pipe 51d opening under a bell 53 suspended from the lever 30 and supplied with air by a branch 13d of the pipe 13b. The regulator 51 is also controlled through a pipe 51<e> by the pressure within the duct 46. Pipes 24<b> convey the air to the supply devices for the various burners of the furnace. The bells of the regulators 51, 49 are formed to receive a heavy sealing liquid such as mercury. The entire group of boilers may be manually controlled by adjusting thumb-screws 16<a> adapted to engage opposite sides of the lever 9 of the master regulator and moved out of the path of the lever during automatic operation. Similar thumb-screws 44a, 44b are provided on the primary regulators 7, and the regulators 32, 41, 49 may be adjusted by varying the tension of springs 43. The master regulator is coupled by a flexible cord to an indicator 15. Specification 282,411 also is referred to.