Patent GB-595747-A (GB)
Title: Improved means for controlling the cyclic operation of components of a power plant
IPC: F15B21/02
Filed: 1943-11-19
Abstract: 595,747. Power plant. ENGLISH ELECTRIC CO., Ltd., and WELSH, R. J. Nov. 19, 1943, No. 19398. Addition to 595,546. [Class 110 (iii)] [Also in Groups XXVII and XXXV] The parent Specification dealt with a number of power units, such as free-piston internalcombustion air compressors L, M, N, P, acting as gas generators or supplying a turbine or other engine, which are started up and stopped in the cyclic sequence L, M, N, P in accordance with plant-load conditions. In place of the compressors, for other type plants, the components L, M, N, P may be electric generators, rotary converters, or arc rectifiers. In the present Specification, the stopping and starting of e.g. component M is influenced by both components L and M the control device M84 taking up one position when M is in action and L at rest, and taking up another position when the component L is in action and M at rest. Other components L, N, P are similarly controlled. The starting and stopping signals are applied to lines L76, L77, &c., controlled by a valve 79. A starting relay L49, for L, is supplied with fluid through L75, and operates a master starting valve L55. The latter opens to admit compressed air from a supply 61 through pipe L62 End a valve L63 to buffer cylinders at each en 3 of the free-piston device. Valve L63 shuts off the air supply in response to the starting of the power component. The component can be stopped by applying fluid pressure to the pipe L74 to operate the stopping relay L70 which shuts off the fuel supply. On the stopping of a power component, means under the control o' two further devices L32, L35 cause the opposed piston units to be separated and the whole component set in readiness for automatic re-starting, e.g. as described in Specification 595,547, [Group XXVII]. A running indicator L37 is a valve which, when the component is at rest, allows fluid pressure from line 42 to pass to the pipe L33, but cuts off this pressure supply and connects L33 to exhaust when the component is in action. The components will start up, or close down, in response to successive signals, or one long-sustained signal, under control members L83, M83, &c. Fluid pressure from M37, when component M is at rest, is applied through pipe M33 to the left-hand end of cylinder M83 tending to move piston valve M84 to the right against the force of a spring M85 which tends to return M84 to its mid-position. Fluid pressure from L37 is applied to the righthand end of M83 when L is at rest, tending to move M84 to the left. In Fig. 1, the controls 83 show the piston valve positions for L and P at rest, and M and N in action. In response to the next starting signal from 76, P will start and P37 will cut off pressure from the left-hand end of P83 and the spring P85 will return the piston to its mid-way position in which both the starting relay P49 and the stopping relay P70 are cut off from pipes 76, 77. In the parent Specification is described how a stopping signal is effective to stop a component only if the next component in cyclic order is in operation, this ensuring that a stopping signal is ineffective if there is only one component in operation. This is achieved in the present Specification by including an extra valve on L84, M84, &c., which is closed only when the piston valve is in its right-hand position. A signal to a stopping relay such as M70 has to go by way of this extra valve in the control valve N86, and when N is at rest, this extra valve is closed to prevent the transmission of the stopping signal for component M. Provision may be made for putting one of the components L, M ... &c. entirely out of action without interfering with the cyclic operation of the rest of the plant. This is shown in Fig. 2' where a spring N90 normally presses the piston valve N89 to the right. In this position the valve N89 completes connections between pipes N33 and N87, and pipes M87 and M88 for normal operation. In the left-hand position of the valve N89 (as shown for P86) the latch N91 drops and the device N37 is disconnected from the control device P83 and directly connected to L83 by the connecting together of pipes A87 and P87 as shown by the dotted line. The valve A89 may be manually moved to the left by using handle D91, when component N is to be put out of action. In addition, the valve N89 may be moved to the left if, after a time delay, power component N fails to start on receipt of a starting signal, by means of pressure fluid building up through a restricted orifice N93 to the right-hand end of cylinder N86, causing the piston to move slowly to the left against spring N90 until latch N91 drops and the component N is cut out, a starting signal then passing on to P. Biassed, or unbiassed, electromagnetically actuated relays may be used instead of the piston valves, as mentioned in the parent Specification. The device 79 may be actuated by the turbine governor as described in Specification 595,746. To rest components in turn, the stopping and starting signals may be controlled by a clock.