Bleeder and back-pressure turbine control system

Claim 2

A bleeder and back pressure turbine control system comprising a rotational speed control means for electrically detecting the rotational speed of the turbine and for sending out a control signal, a back pressure control means for electrically detecting the back pressure of the turbine and for sending out another control signal, bleeder pressure control means for electrically detecting the bleeder pressure of the turbine and for sending out still another control signal, a main steam-regulating valve and a bleeder-regulating valve connected to said turbine, electrohydraulic control means for selectively opening and closing said main and bleeder valves, a switching means coupled to each of said back pressure, bleeder pressure, and speed control means, said switching means having a first position for constant speed operation wherein said switching means disconnects said back pressure control device from the control system and having a second position for constant pressure operation wherein said switching means disconnects said rotating speed control device from the control system, and signal control means connected between said switching means and said electrohydraulic control means for causing said main and bleeder valves to open and close in the same direction under the control of said speed control means, and to open and close opposingly to each other under the control of said bleeder pressure control means, when said switching means is in said first position for said constant speed operation, and for causing both said valves to open and close in the same direction under the control of said back pressure control means, and said main steam-regulating valve to open and close under the control of said bleeder pressure control means, when the switching means is in said second position for said constant pressure operation.

Claim 3

A bleeder and back pressure turbine control system as set forth in claim 1, further comprising over speed protection means connected to said control system and which, when the turbine over speeds during the constant pressure operation, receives said control signal from the rotating speed control means and operates said electrohydraulic conTrol means in a manner such that said main steam-regulating valve and said bleeder-regulating valve are thereby instantaneously closed.

Claim 4

A bleeder and back pressure turbine control system as defined in claim 1 wherein said electrohydraulic control means consists of two units of similar organization and connected respectively to said main steam regulating valve and said bleeder-regulating valve.

Claim 5

A bleeder and back pressure turbine control system as defined in claim 1 wherein each of said rotational speed control, back pressure control, and bleeder pressure control means comprises a detector means inclusive of a detecting element, a preset means for presetting an optimum value of, for instance, the rotational speed, bleeder pressure, or back pressure, a comparator means having an output and having inputs connected to said detector and preset means for comparing the detected value with the preset value, and a control means connected to said comparator means output for producing a control signal.

Claim 6

A bleeder and back pressure turbine control system as defined in claim 1, in which said signal control means comprises three gain controllers, a polarity changer, two adders, and means coupling together said controllers, changer and two adders for causing said electrohydraulic control means to control said main steam-regulating valve and the bleeder-regulating valve in proportion to a thermal drop ratio in the high-pressure and the low-pressure turbines.

Claim 7

A bleeder and back pressure turbine control system as defined in claim 5, in which said gain controllers produce output signals, under conditions of equal inputs to said controllers, defined by the respective expressions: H1/(H1+H2); H2/(H1+H2); H2/(H1+H2); wherein H1and H2are the thermal drops due to a high-pressure portion and a low-pressure portion of said turbine, respectively.

Claim 8

In a turbine having a main steam input regulating valve, a bleeder valve, and bleeder and exhaust passages, an improved turbine control system comprising, speed detecting and control means connected to the turbine for producing an electrical signal which is proportional to the rotational speed of the turbine as compared to a predetermined speed signal level; back pressure detecting and control means connected to the turbine exhaust passage for producing an electrical signal which is proportional to a pressure within the exhaust passage as compared to a predetermined back pressure signal level; bleeder pressure detecting and control means connected to the bleeder passage of the turbine for producing an electrical signal which is proportional to a pressure within the bleeder passage as compared to a predetermined bleeder pressure signal level; first electrohydraulic control means connected to the main steam input regulating valve for actuation to selectively open and close said main valve; second electrohydraulic control means connected to said bleeder valve for actuation to selectively open and close said bleeder valve; signal control means electrically connected to said first and second electrohydraulic control means for producing signals for actuating said first and second electrohydraulic control means; and switching means having a first constant speed-controlling position and a second constant pressure controlling position, said switching means being connected between said signal control means and said speed, back pressure, and bleeder pressure detecting and control means for coupling said bleeder pressure and speed detecting and control means to said signal control means when said switching means is in said first position, and for coupling said bleeder pressure and back pressure detecting and control means to said signal control means when said switching means is in said second position, said signal control means comprising means for actuating said first and second electrohydraulic means, when said switching means is in said first positIon, to open and close said main and bleeder valves together in response to said signals produced by said speed detecting and control means, and to open and close said main and bleeder valves in opposition in response to said signals produced by said bleeder pressure detecting and control means, and said signal control means further comprising means for actuating said first and second electrohydraulic means, when said switching means is in said second position, to open and close said main and bleeder valves together in response to said signals produced by said back pressure detecting and control means, and to open and close said main valve in response to said signals produced by said bleeder pressure detecting and control means.

Claim 9

In a turbine having a main steam input regulating valve, a bleeder valve, and bleeder and exhaust passages, an improved turbine control system comprising, speed detecting and control means connected to the turbine for producing an electrical signal which is proportional to the rotational speed of the turbine as compared to a predetermined speed signal level; back pressure detecting and control means connected to the turbine exhaust passage for producing an electrical signal which is proportional to a pressure within the exhaust passage as compared to a predetermined back pressure signal level; bleeder pressure detecting and control means connected to the bleeder passage of the turbine for producing an electrical signal which is proportional to a pressure within the bleeder passage as compared to a predetermined bleeder pressure signal level; first electrohydraulic control means connected to the main steam input regulating valve for actuation to selectively open and close said main valve; second electrohydraulic control means connected to said bleeder valve for actuation to selectively open and close said bleeder valve; signal control means electrically connected to said first and second electrohydraulic control means for producing signals for actuating said first and second electrohydraulic control means; and switching means having a first constant speed-controlling position and a second constant pressure controlling position, said switching means being connected between said signal control means and said speed, back pressure, and bleeder pressure detecting and control means for coupling said bleeder pressure and speed detecting and control means to said signal control means when said switching means is in said first position, and for coupling said bleeder pressure and back pressure detecting and control means to said signal control means when said switching means is in said second position, said signal control means comprising means for actuating said first and second electrohydraulic means, when said switching means is in said first positIon, to open and close said main and bleeder valves together in response to said signals produced by said speed detecting and control means, and to open and close said main and bleeder valves in opposition in response to said signals produced by said bleeder pressure detecting and control means, and said signal control means further comprising means for actuating said first and second electrohydraulic means, when said switching means is in said second position, to open and close said main and bleeder valves together in response to said signals produced by said back pressure detecting and control means, and to open and close said main valve in response to said signals produced by said bleeder pressure detecting and control means.

Claim 10

An improved turbine control system as set forth in claim 7, further comprising overspeed protective circuit means connected to said speed detecting and control means and said signal control means for producing an electrical signal for causing said signal control means to actuate said first and second electrohydraulic means to close said main and bleeder valves in response to an overspeed condition detected by said speed detecting and control means.

Claim 11

An improved turbine control system as set forth in claim 7, in which said speed detecting and control means, said back pressure detecting and control means, said bleeder pressure detecting and control means each includes detector means for producing a signal proportional to and corresponding respectively to the speed, back pressure and bleeder pressure of the turbine, preset means for producing a signal having a desired level in comparison to the signal produced by said detector means, comparator means connected to said detector means and said preset means for producing a signal proportional to the difference between said detector and preset signals, and control means for generating one of said respective electrical signals in response to said comparator signal.