# US 8,739,963 B2 · Screw-type heat-exchanger system with variable-clocking screw conveyors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,963 B2 - Document ID: US8739963B2 - Status: Granted - Kind: B2 - Application number: 13/372,045 - Filed: 2012-02-13 - Published: 2012-08-16 - Granted: 2014-06-03 - Earliest claimed: 2011-02-11 - Assignees: Therma-Flite, Inc. - Applicants: Robert Nickerson; John Whitney - Inventors: Robert Nickerson; John Whitney - Web page: https://patentgrep.com/patent/US8739963B2 ## CPC - B65G 33/34: Applications of driving gear - B65G 33/18: with multiple screws in parallel arrangements {, e.g. concentric} - B65G: TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS (packaging B65B; handling thin or filamentary materials, e.g. paper sheets or thread, B65H; cranes B66C; portable mobile or lifting or hauling appliances, e.g. hoists, B66D; devices for lifting or lowering goods for loading or unloading purposes, e.g. fork-lift trucks, B66F9/00; emptying bottles, jars, casks, barrels or similar containers, not otherwise provided for, B67C9/00; delivering or transferring liquids B67D; filling or discharging vessels for liquefied, solidified or compressed gases F17C; pipe-line systems for fluids F17D) ## Abstract A system for treating a material includes first and second screw conveyors each having a rotary shaft and a helical flight extending radially outward therefrom, the flighting of the screw conveyors overlapping with each other, and first and second actuators operably coupled to the first and second screw conveyors in a one-to-one dedicated relationship to rotationally drive the screw conveyors independently of each other. In typical embodiments, also included is a system for varying the clocking position of the screw conveyors relative to each other, wherein the screw conveyor flights are axially adjusted with respect to each other between a normal position and an advanced and/or retarded position. Also disclosed are methods of varying the axial position of the screw conveyor flights with respect to each other between the normal and advanced and/or retarded positions. ## Claims ### Claim 1 A system for treating a material, comprising: first and second screw conveyors arranged in parallel, each screw conveyor having a rotary shaft and a helical flight extending radially outward therefrom, the flighting of the first screw conveyor overlapping with the flighting of the second screw conveyor; and first and second actuators operably coupled to the first and second screw conveyors, respectively, in a one-to-one dedicated relationship and operable to rotationally drive the screw conveyors independently of each other at a same or differing rotational speeds; and a control system programmed to control the actuators to variably adjust the relative rotational speed of the screw conveyors to adjust an axial position of the flights with respect to each other to thereby control a clocking position of the screw conveyors relative to each other between an advanced clocking position and a retarded clocking position and to adjust the axial position of the flights with respect to each other to prevent the overlapping flights of the screw conveyors from colliding with each other, wherein in the advanced clocking position a front surface of the flighting of the first screw conveyor is in close proximity to a back surface of the flighting of the second screw conveyor, and in the retarded clocking position a back surface of the flighting of the first screw conveyor is in close proximity to a front surface of the flighting of the second screw conveyor. ### Claim 2 (depends on 1) The screw-conveyor system of claim 1, wherein control system is further programmed to control the actuators to adjust and control the clocking position of the screw conveyors repeatedly between the advanced clocking position and the retarded clocking position in an oscillating manner to cause the material to repeatedly move between forward and rearward. ### Claim 3 (depends on 1) The screw-conveyor system of claim 1, wherein in the advanced clocking position the screws are about 270 degrees apart, and in the retarded clocking position the screws are about 90 degrees apart. ### Claim 4 (depends on 1) The screw-conveyor system of claim 1, wherein the close proximity of the front surface of the flighting of the first screw conveyor and the back surface of the flighting of the second screw conveyor in the advanced clocking position forms a dynamic traveling dam that pushes the material forward to achieve a positive transport of the material along the screw conveyors. ### Claim 5 (depends on 1) The screw-conveyor system of claim 1, wherein the control system is further programmed to control the actuators to adjust and control the clocking position of the screw conveyors by driving the first screw conveyor faster than the second screw conveyor until the advanced clocking position is reached, then driving the second screw conveyor faster than then first screw conveyor until the retarded clocking position is reached, then repeating the sequence in an oscillating manner. ### Claim 6 (depends on 1) The screw-conveyor system of claim 1, wherein the control system is further programmed to control the actuators to drive the first screw conveyor at a fixed speed and to drive the second screw conveyor at a variable speed, wherein the second screw conveyor is driven in a forward angular direction then a reverse angular direction to axially move the flights between the advanced and retarded positions. ### Claim 7 (depends on 6) The screw-conveyor system of claim 6, wherein the control system is further programmed to control the actuators to drive the second screw conveyor at a variable speed with a rate of change that is a sine function so that the rate of speed change of the second screw conveyor is smaller as the screw conveyors near the advanced and retarded positions and greater at a midpoint between the advanced and retarded positions. ### Claim 8 (depends on 1) The screw-conveyor system of claim 1, wherein the control system is further programmed to control the actuators to drive the first and second screw conveyors at a common speed but in opposite angular directions until the screw conveyors approach the advanced position, then to reverse the angular directions of the screw conveyors at the same time and drive the screw conveyors until they approach the retarded position, then to repeat the sequence in an oscillating manner. ### Claim 9 (depends on 1) The screw-conveyor system of claim 1, wherein the control system is further programmed to control the actuators to adjust the clocking position of the screw conveyors from or to a normal clocking position. ### Claim 10 (depends on 1) The screw-conveyor system of claim 1, wherein the control system is further programmed to control the actuators to drive the screw conveyors both in co-rotation, both in counter-rotation, or one in co-rotation and the other in counter-rotation. ### Claim 11 (depends on 1) The screw-conveyor system of claim 1, wherein the control system includes first and second screw-position sensors, first and second adjustable speed drives (ASDs), and a controller operated by a control program, wherein the first and second screw-position sensors are operably coupled to the first and second screw conveyors, respectively, or to the first and second actuators, respectively, and adapted to detect screw clocking positions, wherein the first and second ASDs are operably coupled to the first and second actuators, respectively, and adapted to vary the speeds of the screw conveyors, and wherein the controller communicates with the screw-position sensors and the ASDs to receive screw-position information and based thereon adjust and control the clocking position of the screw conveyors between the advanced clocking position and the retarded clocking position. ### Claim 12 (depends on 1) The screw-conveyor system of claim 1, further comprising: a third or more additional screw conveyors, each additional screw conveyor having a rotary shaft and a helical flight extending radially outward therefrom, the flighting of each of the additional screw conveyor overlapping with the flighting of an adjacent one of the screw conveyors; and a third or more additional actuators operably coupled to the third or more additional screw conveyors, respectively, in a one-to-one dedicated relationship and operable to rotationally drive the additional screw conveyors. ### Claim 13 A system for thermally treating a material, comprising: first and second heat-exchange screw conveyors arranged in parallel, each screw conveyor having a rotary shaft and a helical flight extending radially outward therefrom, the flighting of the first screw conveyor overlapping with the flighting of the second screw conveyor; first and second actuators operably coupled to the first and second screw conveyors, respectively, in a one-to-one dedicated relationship and operable to rotationally drive the screw conveyors independently of each other at a same or differing rotational speeds; and a control system including first and second screw-position sensors, first and second adjustable speed drives (ASDs), and a controller operated by a control program, wherein the first and second screw-position sensors are operably coupled to the first and second screw conveyors, respectively, or to the first and second actuators, respectively, and adapted to detect screw clocking positions of the respective screw conveyors, wherein the first and second ASDs are operably coupled to the first and second actuators, respectively, and adapted to control the actuators to vary the speeds of the respective screw conveyors, wherein the controller communicates with the screw-position sensors and the ASDs to receive screw-position information and based thereon adjust and control the clocking position of the screw conveyors, wherein the control system is programmed to control the actuators to variably adjust the relative rotational speed of the screw conveyors to adjust an axial position of the flights with respect to each other to thereby control a clocking position of the screw conveyors relative to each other so that the overlapping flights of the screw conveyors do not collide with each other, wherein control system is further programmed to control the actuators to adjust and control the clocking position of the screw conveyors repeatedly between an advanced clocking position and a retarded clocking position in an oscillating manner to cause the material to repeatedly move between forward and rearward, wherein in the advanced clocking position a front surface of the flighting of the first screw conveyor is in close proximity to a back surface of the flighting of the second screw conveyor, wherein in the retarded clocking position a back surface of the flighting of the first screw conveyor is in close proximity to a front surface of the flighting of the second screw conveyor, and wherein the close proximity of the front surface of the flighting of the first screw conveyor and the back surface of the flighting of the second screw conveyor in the advanced clocking position forms a dynamic traveling dam that pushes the material forward to achieve a positive transport of the material along the screw conveyors. ### Claim 14 (depends on 13) The screw-conveyor system of claim 13 , wherein the control system is further programmed to control the actuators to drive the screw conveyors both in co-rotation, both in counter-rotation, or one in co-rotation and the other in counter-rotation. ### Claim 15 A method for treating a material, comprising: providing first and second screw conveyors arranged in parallel, each screw conveyor having a rotary shaft and a helical flight extending radially outward therefrom, the flighting of the first screw conveyor overlapping with the flighting of the second screw conveyor, and first and second actuators operably coupled to the first and second screw conveyors, respectively, in a one-to-one dedicated relationship; controlling the actuators to rotationally drive the screw conveyors independently of each other at a same or differing rotational speeds to variably adjust the relative rotational steed of the screw conveyors to adjust an axial position of the flights with respect to each other to thereby control a clocking position of the screw conveyors elative to each other between an advanced clocking position and a retarded clocking position and to adjust the axial position of the flights with respect to each other to prevent the overlapping flights of the screw conveyors from colliding with each other, wherein in the advanced clocking position a front surface of the fighting of the first screw conveyor is in close proximity to a back surface of the flighting in of the second screw conveyor, or and in the retarded clocking position a back surface of the flighting of the first screw conveyor is in close proximity to a front surface of the fighting of the second screw conveyor. ### Claim 16 (depends on 15) The method of claim 15, further comprising controlling the actuators to control the clocking position of the screw conveyors between the advanced clocking position and the retarded clocking position in an oscillating manner to cause the material to repeatedly move between forward and rearward. ### Claim 17 (depends on 15) The method of claim 15, further comprising controlling the actuators to adjust and control the clocking position of the screw conveyors by driving the first screw conveyor faster than the second screw conveyor until the advanced clocking position is reached, then driving the second screw conveyor faster than then first screw conveyor until the retarded clocking position is reached, then repeating the sequence in an oscillating manner. ### Claim 18 (depends on 15) The method of claim 15, further comprising controlling the actuators to drive the first screw conveyor at a fixed speed and to drive the second screw conveyor at a variable speed, wherein the second screw conveyor is driven in a forward angular direction then a reverse angular direction to axially move the flights between the advanced and retarded positions. ### Claim 19 (depends on 18) The method of claim 18, further comprising controlling the actuators to drive the second screw conveyor at a variable speed with a rate of change that is a sine function so that the rate of speed change of the second screw conveyor is smaller as the screw conveyors near the advanced and retarded positions and greater at a midpoint between the advanced and retarded positions. ### Claim 20 (depends on 15) The method of claim 15, further comprising controlling the actuators to drive the first and second screw conveyors at a common speed but in opposite angular directions until the screw conveyors approach the advanced position, then to reverse the angular directions of the screw conveyors at the same time and drive the screw conveyors until they approach the retarded position, then to repeat the sequence in an oscillating manner. ### Claim 21 (depends on 15) The method of claim 15, further comprising controlling the actuators to drive the screw conveyors both in co-rotation, both in counter-rotation, or one in co-rotation and the other in counter-rotation. ### Claim 22 (depends on 15) A non-transitory computer-readable medium encoded with computer-executable instructions for performing the method of claim 15. ### Claim 23 (depends on 1) The screw-conveyor system of claim 1, wherein: with a 360-degree section of the flighting of the first screw conveyor including portions overlapping with and interposed between axially-adjacent leading and trailing 360-degree sections of the flighting of the second screw conveyor, in the advanced clocking position a front surface of the flight section of the first screw conveyor is closer to a back surface of the leading flight section of the second screw conveyor than a back surface of the flight section of the first screw conveyor is to a front surface of the trailing flight section of the second screw conveyor, and in the retarded clocking position the back surface of the flight section of the first screw conveyor is closer to the front surface of the trailing flight section of the second screw conveyor than the front surface of the flight section of the first screw conveyor is to the back surface of the leading flight section of the second screw conveyor.