Control system for a two boiler, single turbine generator power producing unit

Claim 2

In a control system for a two boiler - single turbine power producing unit, the combination comprising, means generating a master demand signal corresponding to the total boiler output required to meet the desired output of said power producing unit, a ratio controller responsive to said master demand signal including means generating a first primary boiler demand signal for one of said boilers varying in predetermined ratio with the magnitude of said master demand signal and means generating a second primary boiler demand signal for the other of said boilers corresponding in magnitude to the difference between the magnitudes of said master demand signal and said first boiler demand signal.

Claim 3

In a control system as set forth in claim 1 further including means for adjusting said predetermined ratio between the magnitudes of said master demand signal and said first boiler primary demand signal.

Claim 4

In a control system as set forth in claim 2 further including a first means adjusting said predetermined ratio responsive to a condition limiting the output of one of said Boilers and a second means adjusting said predetermined ratio responsive to a condition limiting the output of the other of said boilers.

Claim 5

In a control system as set forth in claim 3 wherein the first and second means each include means inhibiting limiting the boiler output until said condition exceeds a first predetermined limit and thereafter adjusting said predetermined ratio as required to maintain said limiting condition within a second predetermined limit.

Claim 6

A control system as set forth in claim 3 wherein the first and second means each include means generating a signal corresponding in magnitude to the limiting condition, and means limiting the primary boiler demand signal to the magnitude of said last named signal.

Claim 7

A control system as set forth in claim 5 wherein the first and second means each include means generating a signal corresponding to the difference between the primary boiler demand signal and the limited boiler demand signal, means selecting the greater of the last named signals and means modifying said master demand signal responsive to said last named signal.

Claim 8

A control system as set forth in claim 6 further including means initially delaying the modification of said master demand signal for a specified increment of time.

Claim 9

In a control system for a power producing unit comprising a boiler A and a boiler B supplying steam in parallel to a single turbine, the combination comprising, means generating a boiler A demand signal, means generating a boiler B demand signal, means responsive to the boiler A demand signal maintaining the rate of fuel supply to boiler A in functional relationship to the boiler A demand signal, means responsive to the boiler B demand signal maintaining the rate of fuel supply to boiler B in functional relationship to the boiler B demand signal and means modifying the functional relationship between said demand signals and the rates of fuel supply to boilers A and B in accordance with the integral with respect to time of deviations in turbine throttle steam temperature from set point.

Claim 10

In a control system for a power producing unit comprising a boiler A and a boiler B supplying steam in parallel to a single turbine, the combination comprising, means generating a boiler A demand signal, means generating a boiler B demand signal, means responsive to the boiler A demand signal maintaining the rate of fuel supply to boiler A in functional relationship to the boiler A demand signal, means responsive to the boiler B demand signal maintaining the rate of fuel supply to boiler B in functional relationship to the boiler B demand signal and means modifying the functional relationship between said demand signals and the rates of fuel supply to boilers A and B in accordance with the integral with respect to time of deviations in turbine throttle steam temperature from set point.

Claim 11

A control system as set forth in claim 8 further including means modifying the functional relationship between the boiler A demand signal and the rate of fuel supply to boiler A in one sense and modifying the functional relationship between the boiler B demand signal and the rate of fuel supply to boiler B in opposite sense responsive to the difference in the steam temperatures of boiler A and boiler B whereby the steam temperature of boiler A is maintained in desired relationship to the steam temperature of boiler B.

Claim 12

In a control system for a power producing unit comprising a boiler A supplying steam to the high pressure section of a turbine and reheat steam to the low pressure section of the turbine and a boiler B supplying steam to the high pressure section of said turbine and reheat steam to the low pressure section of said turbine in parallel with boiler A, the combination comprising, means generating a boiler A demand signal, means generating a boiler B demand signal, means responsive to the boiler A demand signal varying the rate of flow of reheat steam through boiler A in functional relationship to changes in the boiler A demand signal and means responsive to the boiler B demand signal varying the rate of flow of reheat steam through boiler B in functional relationship to changes in the boiler B demand signal.

Claim 13

In a control system for a power producing unit comprising a boiler A supplying steam to the high pressure section of a turbine and reheat steam to the low pressure section of the turbine and a boiler B supplying steam to the high pressure section of said turbine and reheat steam to the low pressure section of said turbine in parallel with boiler A, the combination comprising, means generating a boiler A demand signal, means generating a boiler B demand signal, means responsive to the boiler A demand signal varying the rate of flow of reheat steam through boiler A in functional relationship to changes in the boiler A demand signal and means responsive to the boiler B demand signal varying the rate of flow of reheat steam through boiler B in functional relationship to changes in the boiler B demand signal.

Claim 14

In a control system as set forth in claim 10 further including means modifying the functional relationship between the boiler A demand signal and boiler A reheat flow in one sense and the functional relationship between the boiler B demand signal and boiler B reheat flow in opposite sense comprising, means generating a first signal corresponding to the difference between boiler A reheat flow and boiler A demand signal, means generating a second signal corresponding to the difference between boiler B reheat flow and Boiler B demand signal, means generating a third signal corresponding to the difference between said first and second signals and means responsive to said third signal modifying the boiler A reheat flow in one sense and the boiler B reheat flow in opposite sense whereby the boiler A reheat flow is maintained in desired functional relationship to the boiler B reheat flow.

Claim 15

A control system as set forth in claim 11 further including means increasing the boiler A reheat steam flow upon the boiler A hot reheat steam temperature exceeding set point and simultaneously decreasing the boiler B reheat steam flow and vice versa.

Claim 16

A control system as set forth in claim 12 further including means increasing the reheat steam flow through that boiler having the higher hot reheat steam temperature above set point and simultaneously decreasing the reheat steam flow through the other boiler.

Claim 17

A control system as set forth in claim 11 further including means increasing the boiler A reheat steam flow upon the boiler A hot reheat steam temperature exceeding the boiler B hot reheat steam temperature and simultaneously decreasing the boiler B reheat steam flow and vice versa.