Patent GB-287966-A (GB)
Title: Improvements relating to regulating systems for fluid supply
IPC: G05D7/01
Filed: 1926-09-23
Abstract: 287,966. Florez, L. de. Sept. 23, 1926. Liquid fuel, gas, and air supply.-A. regulating device for apparatus intended to operate under any desired conditions comprises means for controlling a fluid flow to maintain the desired condition, and a device acting at determined time intervals and adapted, if the desired condition is departed from for more than a predetermined time (departures in opposite directions being reckoned as of opposite sign), to actuate the fluid control to restore the desired condition, said device being adapted also to effect temporary corrections of any undefined amount but in the right direction while operating to actuate the main fluid control. The device is applicable to the control of liquid, gaseous, or powdered fuel, or air for combustion, in response to conditions of temperature or pressure, and in general, to the control of flow, pressure, temperature, volume, weight, and other quantities. In the application to the control of the temperature of a still for cracking hydrocarbons, .the oil pipe 11 in a furnace 13 is provided with a thermocouple 14 connected to an indicating system 15 whereby the temperature is indicated by a galvanometer needle 20 moving in a path indicated by the dotted lines. A bar 26 is continuously reciprocated vertically against the needle 20, whose mid position corresponds to the desired temperature. If the temperature has varied, the needle is caused to strike one of the bell crank levers 21. 22, the lower end of which tilts a bar 27 by striking against one of the pins 30 or 31, according as the temperature is too high or too low. A shaft 36 is continuously rotated, and carries cams 34, 35, one of which contacts with the end of the bar 27 if the latter is tilted. The period of contact of the cam with the bar varies with the tilting of the bar, which depends on the amount of deflection of the needle 20, and thus on the temperature variation, or the cam may have a contact piece at its tip only, so that a constant time of contact is obtained. The burner 12 is supplied through a main pipe 40, 42, 45, and through branch pipes 43, 44. The pipe 42 is controlled by a main valve 46, the pipe 43 by a valve 48 normally open, and the pipe 44 by a valve 49 normally closed. Assuming that the temperature is too low, and that the cam 35 is thereby caused to make contact with the piece 33, the solenoid 51 is energized and the valve 49 fully opened as long as the circuit is complete, thereby adding a puff of fuel to the steady flow. This intermittent correction of the supply continues to operate as long as the needle 20 is deflected. The air supply is controlled by a main valve 58, and by an auxiliary valve 60 controlled by the solenoid 62 which is actuated at the same time as the solenoid 51 so that the opening cf the valve 60 is varied intermittently. At the same time that the solenoids 51, 62 are energized the electric motors 47, 59 are also energized, so that they rotate at intervals synchronously with the valve openings. The motor shaft 70, Fig. 3, has a worm 71 which operates worm wheel 72, worm 73 and worm wheel 74 carrying a finger 77. A Geneva stop pinion 75 is loosely mounted on the same shaft and carries a pin 76 in the path of the finger 77, while the pinion 75 carries a single tooth 78 engaging with a wheel 80 the spindle of which, 81, carries the valve 46. Successive actuations of the motor 47 in the same direction rotate the finger 77 in, say, a clockwise direction, but the pin 76 is not actuated until the finger 77 has moved nearly a complete revolution from the position shown. If, therefore, the puffs of fuel which are supplied through the valve 49 do. not restore the desired temperature, the time of departure of this temperature the predetermined point is integrated by the above-described mechanism until the pin 76 is finally actuated, the wheel 80 is rotated one tooth, and the main valve 46 is opened slightly to a new setting. If the variation of temperature still persists, the time integration is again effected, and the wheel 80 is finally moved another tooth after the pin 77 has rotated through a complete circle. The main valve 46 has a sufficiently fine adjustment to maintain accurately by itself the desired steady temperature. The control by the auxiliary valve 49 is not a fine adjustment superposed on the main valve but corrects temporary fluctuations only, while any persisting deviation of temperature is corrected by a re-setting of the main valve through the integrating mechanism. If the temperature is too high, the solenoid 50 is actuated to close the valve 48 intermittently, and the motors 47, 59, are rotated in the opposite direction. The main valves 46, 58 are therefore only re-set when the time integration effected by the Geneva stop mechanism reaches a predetermined algebraic sum since the last setting, rotations in opposite directions being reckoned as of opposite sign.