Compression apparatus with variable speed screw and method
First Claim
1. A two stage compressor feed apparatus operable to compress loose feedstock material, said feed apparatus comprising:
- a first compressor stage and a second compressor stage;
said first compressor stage having a screw, said screw having a volute operable to drive the feedstock forward in an axial direction while compressing the feedstock;
said second compressor stage having an axial accommodation permitting an end of said screw to extend therethrough;
said first compressor stage having a drive connected to operate said screw;
said drive being a variable speed drive;
sensors mounted to monitor operation of said screw and said second compressor stage;
a controller operable to receive signals from said sensors and to control operation of said screw; and
said controller being operable continuously to vary operating speed of said drive in response to operation of said second compressor stage;
said second compressor stage has a duty cycle, said duty cycle including a first portion and a second portion;
during said first portion of said second compressor stage duty cycle said controller is programmed to urge said screw to operate in a first speed regime, and in said second portion of said second compressor stage duty cycle said controller is programmed to operate said screw in a second, different speed regime;
said first portion of said dut cycle is a piston advancing portion, and said second stage of said duty cycle is a piston retracting portion; and
said controller is programmed to reduce speed of said screw during said piston retracting portion of said duty cycle, and to increase speed of said screw during said piston advancing portion of said duty cycle.
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Accused Products
Abstract
An apparatus is provided for compressing a loose solid feedstock. The apparatus includes a two stage compressor. The first compression stage is a screw compressor. The second compressor stage is a reciprocating compressor. The reciprocating compressor operates co-axially with, and receives its feed from, the screw compressor. A choke cone maintains pressure in the outfeed from the compressor stages. The reciprocating compressor, the screw compressor, and the choke cone are all adjustable in real time to control the compression of the feedstock according to a pre-programmed schedule that need not have equal compression and retraction strokes. The operation of the screw compressor may be advanced or eased off depending on the motion of the reciprocating compressor. The operation of the choke cone may be actively controlled to obtain a coordination with the compressor stages.
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Citations
14 Claims
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1. A two stage compressor feed apparatus operable to compress loose feedstock material, said feed apparatus comprising:
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a first compressor stage and a second compressor stage; said first compressor stage having a screw, said screw having a volute operable to drive the feedstock forward in an axial direction while compressing the feedstock; said second compressor stage having an axial accommodation permitting an end of said screw to extend therethrough; said first compressor stage having a drive connected to operate said screw; said drive being a variable speed drive; sensors mounted to monitor operation of said screw and said second compressor stage; a controller operable to receive signals from said sensors and to control operation of said screw; and said controller being operable continuously to vary operating speed of said drive in response to operation of said second compressor stage; said second compressor stage has a duty cycle, said duty cycle including a first portion and a second portion; during said first portion of said second compressor stage duty cycle said controller is programmed to urge said screw to operate in a first speed regime, and in said second portion of said second compressor stage duty cycle said controller is programmed to operate said screw in a second, different speed regime; said first portion of said dut cycle is a piston advancing portion, and said second stage of said duty cycle is a piston retracting portion; and said controller is programmed to reduce speed of said screw during said piston retracting portion of said duty cycle, and to increase speed of said screw during said piston advancing portion of said duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A two stage compression process for compressing loose feedstock material, comprising:
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providing a first compressor stage and a second compressor stage, said first compressor stage having a screw, said screw having a volute operable to drive the feedstock forward in an axial direction while compressing the feedstock; said second compressor stage having an axial accommodation permitting an end of said screw to extend therethrough; said first compressor stage having a drive connected to operate said screw; said drive being a variable speed drive; sensors mounted to monitor operation of said screw and said second compressor stage; a controller operable to receive signals from said sensors and to control operation of said screw; and operating said controller continuously to vary operating speed of said drive in response to operation of said second compressor stage; said second compressor stage has a duty cycle, said duty cycle including a first portion and a second portion; during said first portion of said second compressor stage duty cycle said controller is programmed to urge said screw to operate in a first speed regime, and in said second portion of said second compressor stage duty cycle said controller is programmed to operate said screw in a second, different speed regime; and said first portion of said duty cycle is a piston advancing portion and said second portion of said duty cycle is a piston retracting portion, and said process including at least one of a) reducing speed of said screw during said piston retracting portion of said duty cycle, and b) increasing speed of said screw during said piston advancing portion of said duty cycle. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification