Blower system and control system therefor

Abstract

An automatic control system for high pressure blower applications prevents surging under variable supply flow rate requirements and achieves maximum efficiency of operation. The supply flow rate establishes the set point of a proportional plus reset controller, the latter receiving a feedback signal corresponding to the static discharge pressure of the supply blower and responding thereto for controlling the output of the supply blower. A return blower is controlled either through a characterizer relay in proportion to the control of the supply blower to maintain a fixed precalibrated relationship between supply and return flow rates or by a further proportional plus reset controller responsive to the supply flow rate, for establishing the set point thereof, and to the return flow rate, as a feedback signal thereto, for controlling the output of the return blower.

What is claimed is: 
     
       1. A blower control system comprising: first means for sensing the supply flow rate produced by a supply blower and generating an output .Iadd.signal .Iaddend.representative thereof,   second means for sensing the discharge pressure produced by the supply blower and generating an output .Iadd.signal .Iaddend.representative thereof,   control means responsive to .[.the outputs.]. .Iadd.said output signals .Iaddend.of said first and second sensing means for producing a control output .Iadd.signal .Iaddend.dependent on the difference between a desired relationship and the sensed relationship of the supply flow rate and the discharge pressure of the supply blower, .Iadd.the output signal representative of the supply flow rate being utilized as a varying set point by said control means in producing said control output signal, .Iaddend.and   adjustment means responsive to .[.the.]..Iadd.said .Iaddend.control output .Iadd.signal .Iaddend.for adjusting the output of .[.said.]. .Iadd.the .Iaddend.supply blower to attain said desired relationship of the supply flow rate and the discharge pressure of .[.said.]. .Iadd.the .Iaddend.supply blower.   
     
     
       2. A blower control system as recited in claim 1, wherein: said control means includes means for presetting therein .[.the.]. .Iadd.said .Iaddend.desired relationship of the supply flow rate and the discharge pressure, and said control means responds .[.to said supply flow rate representative output of said first means to establish a set point of operation, and.]. to said discharge pressure repesentative output .Iadd.signal .Iaddend.of said second means as a feedback signal, for producing .[.the.]. .Iadd.said .Iaddend.control output .Iadd.signal .Iaddend.thereof.   
     
     
       3. A blower control system as recited in claim 1, wherein there is further provided first and second transmitting means associated with said first and second sensing means, respectively, for transmitting the respective outputs thereof to said control means. 
     
     
       4. A blower control system as recited in claim 1, wherein said adjustment means comprises: mechanically adjustable means associated with said supply blower and adapted for actuation to adjust the output thereof, and   means responsive to the control output of said control means for producing a corresponding mechanical actuation for adjusting said mechanically adjustable means.   
     
     
       5. A blower control system as recited in claim 4, wherein said mechanically adjustable means comprise a system of louvers adjustable to vary the inlet air supply to said supply blower. 
     
     
       6. A blower control system as recited in claim 4, wherein said mechanically adjustable means comprise means for adjusting the pitch of the blades of a fan of the supply blower. 
     
     
       7. A blower control system as recited in claim 4, wherein there is further provided: means selectively operable to automatically transmit a signal received thereby and to be manually set to generate and transmit a signal, said selectively operable means being connected to receive the output of said control means and to transmit an output thereof to said adjustment means and effective when set for automatic operation to transmit the control output of said control means to said adjustment means and when selectively set for manual operation to develop and transmit a manually set signal to said adjustment means for adjusting the output of said supply blower. .[.8. A blower control system as recited in claim 1, wherein there is further provided:   a return blower for exhausting air from a facility supplied by the output of said supply blower and returning the exhausted air to said supply blower for recirculation; and   control means for said return blower responsive to the supply flow rate for producing a return control output related thereto for establishing a desired relationship of the return flow rate and the supply flow rate, and   adjustment means responsive to the return control output for adjusting the output of said return blower to attain said desired relationship of the   
     
     
        supply and return flow rates..]. 9. A blower control system as recited in claim .[.8.]. .Iadd.32.Iaddend., where there is further provided: third means for sensing the return flow rate produced by the return blower and generating an output representative thereof, and   said return control means responds to said supply flow rate representative output of said first sensing means to establish a set point of operation and to said return flow third representative output of said third sensing means as a feedback signal, for producing the return control output.   
     
     
        .[.  .  A blower control system as recited in claim 9, wherein there is further provided third transmitting means associated with said third sensing means for transmitting the output thereof to said third control 
     
     
        means..]. 11. A blower control system as recited in claim .[.8.]. .Iadd.32.Iaddend., wherein said return control means comprises characterizer relay means responsive to the control output of said supply control means for producing the return control output in accordance with a 
     
     
        predetermined relationship to said supply control output. 12. A blower control system as recited in claim .[.8.]. .Iadd.32.Iaddend., wherein said adjustment means comprises: mechanically adjustable means associated with said return blower and adapted for actuation to adjust the output thereof, and   means responsive to the control output of said return control means for producing a corresponding mechanical actuation for adjusting said   
     
     
        mechanically adjustable means associated with said return blower. 13. A blower control system as recited in claim .[.8.]. .Iadd.32.Iaddend., wherein .[.said adjustment means comprises.]. .Iadd.there is further provided: .Iaddend. means selectively operable to automatically transmit a signal received thereby and to be manually set to generate and transmit a signal, said selectively operable means being connected to receive the output of said return control means and to transmit an output thereof to said adjustment means and effective when set for automatic operation to transmit the control output of said return control means to said adjustment means and when selectively set for manual operation to develop and transmit a manually set signal to said adjustment means for adjusting the output of   
     
     
        said return blower. 14. A system as recited in claim 1, wherein: said first and second means produce pneumatic signals representative of the sensed supply flow rate and discharge pressure, respectively, and   said control means responds to the pneumatic output signals of said first   
     
     
        and second means to produce a pneumatic control signal. 15. A blower control system as recited in claim 14, wherein said first sensing means produces a pressure differential pneumatic output signal corresponding to 
     
     
        the supply flow rate. 16. A blower control system as recited in claim 15, wherein said first sensing means comprises a pitot tube. .Iadd. 17. A blower control system as recited in claim 1 wherein said control means includes means for presetting therein said desired relationship of the supply flow rate and the discharge pressure. .Iaddend..Iadd. 18. A blower system as recited in claim 1, wherein said control means responds to said discharge pressure representative output signal of said second means as a feedback signal, for producing said control output signal thereof. .Iaddend..Iadd. 19. A blower control system as recited in claim 1, wherein there is further provided means selectively operable to automatically transmit a signal received thereby and to be manually set to generate and transmit a signal, said selectively operable means being connected to receive said output signal of said control means and to transmit an output thereof to said adjustment means and effective when set for automatic operation to transmit said control output signal of said control means to said adjustment means and when selectively set for manual operation to develop and transmit a manually set signal to said adjustment means for adjusting the output of the supply blower. .Iaddend..Iadd. 20. A blower control system comprising: first means for sensing the supply flow rate produced by a supply blower and generating an output signal representative thereof,   second means for sensing the discharge pressure produced by the supply blower and generating an output representative thereof,   first control means responsive to said output signals of said first and second sensing means for producing a control output signal dependent on the difference between a desired relationship and the sensed relationship of the supply flow rate and the discharge pressure of the supply blower,   first adjustment means responsive to said control output signal of said first control means for adjusting the output of the supply blower to attain said desired relationship of the supply flow rate and the discharge pressure of the supply blower,   third means for sensing the return flow rate produced by a return blower and generating an output signal representative thereof,   second control means responsive to said output signals of said first and third sensing means for producing a control output signal dependent on the difference between a desired relationship and the sensed relationship of the supply and return flow rates, and   second adjustment means responsive to said control output signal of said second control means for adjusting the output of the return blower to attain said desired relationship of the supply and return flow rates. .Iaddend..Iadd. 21. A blower control system as recited in claim 20, wherein said first control means utilizes the output signal representative of the supply flow rate as a varying set point and the output signal representative of the discharge pressure of the supply fan as a feedback signal in producing said control output signal thereof. .Iaddend..Iadd. 22. A blower control system as recited in claim 21, wherein said second control means utilizes the output signal representative of the supply flow rate as a varying set point and the output signal representative of the return flow rate as a feedback signal in producing said control output signal thereof. .Iaddend..Iadd. 23. A blower control system as recited in claim 20, wherein said second control means utilizes the output signal representative of the supply flow rate as a varying set point and the output signal representative of the return flow rate as a feedback signal in producing said control output signal thereof. .Iaddend..Iadd. 24. A blower control system as recited in claim 21 wherein said first control means includes means for presetting therein said desired relationship of the supply flow rate and the discharge pressure of the supply blower. .Iaddend..Iadd. 25. A blower control system as recited in claim 23 wherein said second control means includes means for presetting therein said desired relationship of the supply and return flow rates. .Iaddend..Iadd. 26. A blower control system as recited in claim 22 wherein:   said first control means include means for presetting therein said desired relationship of the supply flow rate and the discharge pressure of the supply blower, and   said second control means includes means for presetting therein said desired relationship of the supply and return flow rates. .Iaddend..Iadd. 27. A blower control system as recited in claim 26 wherein said first and second adjustment means each respectively comprises:   mechanically adjustable means associated respectively with the supply blower and the return blower and adapted for actuation to independently adjust the outputs thereof, and   means respectively responsive to the control output signals of said first and second control means for producing a corresponding mechanical actuation for adjusting said respective mechanically adjustable means.   
     
     
        .Iaddend..Iadd. 28.  A blower control system as recited in claim 27 wherein said mechanically adjustable means comprises a system of louvers adjustable to vary the inlet air supply to the supply and return blowers. .Iaddend..Iadd. 29. A blower control system as recited in claim 27 wherein said mechanically adjustable means comprises means for adjusting the pitch of the blades of a fan of the supply and return blowers. .Iaddend..Iadd. 30. A blower control system as recited in claim 27 wherein there is further provided, in association with each of said first and second adjustment means, means selectively operable to automatically transmit a signal received thereby and to be manually set to generate and transmit a signal, said selectively operable means being connected to receive respectively said control output signals of said first and second control means and to transmit an output thereof to the adjustment means with which said selectively operable means is associated and effective when set for automatic operation to transmit said control signal output of said respectively connected control means to said associated adjustment means and when selectively set for manual operation to develop and transmit a manually set signal to said associated adjustment means for adjusting the output of the supply and return blowers. .Iaddend..Iadd. 31. A blower control system as recited in claim 20 wherein there is further provided, in association with each of said first and second adjustment means, means selectively operable to automatically transmit a signal received thereby and to be manually set to generate and transmit a signal, said selectively operable means being connected to receive respectively said control output signals of said first and second control means and to transmit an output thereof to the adjustment means with which said selectively operable means is associated and effective when set for automatic operation to transmit said control signal output of said respectively connected control means to said associated adjustment means and when selectively set for manual operation to develop and transmit a manually set signal to said associated adjustment means for adjusting the output of the supply and return blowers. .Iaddend. .Iadd. 32. A blower control system comprising: first means for sensing the supply flow rate produced by a supply blower and generating an output representative thereof,   second means for sensing the discharge pressure produced by the supply blower and generating an output representative thereof,   control means responsive to the outputs of said first and second sensing means for producing a control output dependent on the different between a desired relationship and the sensed relationship of the supply flow rate and the discharge pressure of the supply blower,   adjustment means responsive to the control output of said control means for adjusting the output of said supply blower to attain said desired relationship of the supply flow rate and the discharge pressure of said supply blower,   a return blower for exhausting air from a facility supplied by the output of said supply blower and returning the exhausted air to said supply blower for recirculation; and   control means for said return blower responsive to the supply flow rate for producing a return control output related thereto for establishing a desired relationship of the return flow rate and the supply flow rate, and   adjustment means responsive to the return control output for adjusting the output of said return blower to attain said desired relationship of the   
     
     
        supply and return flow rate. .Iaddend. .Iadd. 33.  A blower control system as recited in claim 9, wherein there is further provided third transmitting means associated with said third sensing means for transmitting the output thereof to said return control means. .Iaddend.