Exhaust duct having modular, multi zone, spirally arrayed cooling coils and method for cooling

Abstract

An exhaust duct for cooling an exhaust flue. One or more modular coolant coils are disposed about the outer circumference of or within the flue interior cavity for thermal communication with exhaust gas. Each coil has a helical spiral profile extending along the flue axial dimension, an interior lumen there through for passage of coolant provided by a cooling system, and a respective inlet and outlet for respective intake and discharge of coolant. Optionally at least one remotely adjustable valve is coupled to the coolant coil and an industrial automation controller, for regulation of coolant flow rate within the coil. The coolant coils may incorporate one or more coolant temperature sensors in communication with the controller. A plurality of exhaust duct cooling coils may be under common control of the controller, for allocation of coolant among the coils and other portions of the cooling system.

1 . An exhaust duct cooling system, comprising:
 an exhaust flue defining a interior cavity for passage of exhaust gas there through along an axial dimension thereof;   a coolant coil disposed about the flue for thermal communication with exhaust gas, the coil having a helical profile extending along the flue axial dimension, an interior lumen there through for passage of coolant, and a respective inlet and outlet for respective intake and discharge of coolant; and   at least one flow regulator coupled to the coolant coil, for regulation of coolant flow rate within the coil.   
     
     
         2 . The system of  claim 1 , wherein the flow regulator is selected from the group consisting of coolant coil diameter, flow restrictor plate, venturi, orifice, manual or remotely adjustable valve, remote controlled flow valve and solenoid actuated remote control valve. 
     
     
         3 . The system of  claim 1 , further comprising a temperature sensor coupled to the coil, wherein the temperature sensor is in communication with a control system controller, the flow regulator is a remotely adjustable valve coupled to and remotely actuated by the control system, and the control system regulates coolant flow rate based at least in part on coolant temperature information obtained from the temperature sensor. 
     
     
         4 . The system of  claim 3 , further comprising respective inlet and outlet temperature sensors coupled to the coil inlet and outlet, for measuring coolant temperature at each location and the control system regulates coolant flow rate based at least in part on coolant temperature information obtained from both of the inlet and outlet temperature sensors. 
     
     
         5 . The system of  claim 1 , further comprising a plurality of coolant coils disposed about the flue selectively along its length for thermal communication with exhaust gas, each coil having a helical profile extending along the flue axial dimension, an interior lumen there through for passage of coolant, and a respective inlet and outlet for respective intake and discharge of coolant. 
     
     
         6 . The system of  claim 5 , further comprising a temperature sensor coupled to each respective coil, for measuring coolant temperature. 
     
     
         7 . The system of  claim 6 , wherein the temperature sensors are in communication with a control system controller, and at least one adjustable valve is coupled to at least one of the cooling coils and is remotely actuated by the control system, and the control system regulates coolant flow rate in each respective coil based at least in part on coolant temperature information obtained from its respective temperature sensor. 
     
     
         8 . The system of  claim 7 , further comprising respective inlet and outlet temperature sensors coupled to at least one of the coil's inlet and outlet, for measuring coolant temperature at each location and the control system regulates coolant flow rate based at least in part on coolant temperature information obtained from both of the inlet and outlet temperature sensors. 
     
     
         9 . The system of  claim 5 , further comprising respective inlet and outlet temperature sensors coupled to each respective coil inlet and outlet, for measuring coolant temperature. 
     
     
         10 . The system of  claim 9 , wherein the respective temperature sensors for each respective coil are in communication with a control system, each respective coil also having a respective adjustable valve flow regulator coupled to and remotely actuated by the control system, and the control system regulates coolant flow rate in each respective coil based at least in part on difference in measured coolant temperature between the inlet and outlet. 
     
     
         11 . The system of  claim 1 , further comprising a coolant flow bypass between the coolant coil inlet and outlet, for selectively recirculating coolant. 
     
     
         12 . An exhaust duct cooling system, comprising:
 an exhaust flue defining a interior cavity for passage of exhaust gas there through along an axial dimension thereof;   a plurality of coolant coils disposed serially about the flue for thermal communication with exhaust gas, each coil having a helical profile extending along the flue axial dimension, an interior lumen there through for passage of coolant, and a respective inlet and outlet for respective intake and discharge of coolant;   an intake manifold in common parallel fluid communication with the inlets; and   an exhaust manifold in common parallel fluid communication with the outlets.   
     
     
         13 . The system of  claim 12 , further comprising at least one flow regulator coupled to each respective coolant coil, for regulation of coolant flow rate within the coil, the flow regulator selected from the group consisting of coolant coil diameter, flow restrictor plate, venturi, orifice, manual or remotely adjustable valve, remote controlled flow valve and solenoid actuated remote control valve. 
     
     
         14 . The system of  claim 13 , wherein at least one flow regulator is a remotely adjustable valve that is adjustable by a control system controller, and wherein the at least one of the adjustable valves is coupled to and remotely actuated by the control system. 
     
     
         15 . The system of  claim 14 , further comprising a temperature sensor coupled to each respective coil, for measuring coolant temperature, wherein the temperature sensors are in communication with a control system controller, each respective adjustable valve is coupled to and remotely actuated by the control system, and the control system regulates coolant flow rate in each respective coil based at least in part on coolant temperature information obtained from its respective temperature sensor. 
     
     
         16 . The system of  claim 15 , further comprising respective inlet and outlet temperature sensors coupled to at least one of the coil's inlet and outlet, for measuring coolant temperature at each location and the control system regulates coolant flow rate based at least in part on coolant temperature information obtained from both of the inlet and outlet temperature sensors. 
     
     
         17 . The system of  claim 12 , wherein the coil inlets and outlets are coupled to the respective intake and exhaust manifolds by serviceable fluid fittings. 
     
     
         18 . The system of  claim 12 , further comprising a coolant flow bypass between at least one coolant coil inlet and outlet, for selectively recirculating coolant. 
     
     
         19 . The system of  claim 18  further comprising a remote actuated valve in the bypass. 
     
     
         20 . A method for cooling an exhaust flue that defines an interior cavity for passage of exhaust gas there through along an axial dimension thereof, comprising:
 orienting a coolant coil about the flue for thermal communication with exhaust gas, the coil having:
 a helical profile extending along the flue axial dimension, 
 an interior lumen there through for passage of coolant, 
 a respective inlet and outlet for respective intake and discharge of coolant, and 
   coupling at least one flow regulator to the coolant coil, for regulation of coolant flow rate within the coil;   feeding coolant through the intake and discharging the coolant through the outlet at a flow rate;   measuring coolant temperature in the coil with at least one temperature sensor coupled thereto; and   regulating coolant flow rate with the flow regulator based at least part on measured coolant temperature.   
     
     
         21 . The method of  claim 20 , wherein the flow regulator is a valve, the temperature sensor and valve are coupled to a controller in communication therewith, the controller performing the measuring and regulating steps. 
     
     
         22 . The method of  claim 21 , wherein the coolant is provided by a coolant system coupled to the inlet and outlet of the coil and the controller varies the desired coolant temperature based on coolant system operational parameters. 
     
     
         23 . The method of  claim 20 , further comprising:
 orienting a plurality of coolant coils disposed serially about the flue for thermal communication with exhaust gas, each coil, having a helical profile extending along the flue axial dimension, an interior lumen there through for passage of coolant, and a respective inlet and outlet for respective intake and discharge of coolant;   coupling at least one adjustable valve flow regulator to each coolant coil, for regulation of coolant flow rate within the respective coil; and   for each respective coil, performing the feeding, measuring and regulating steps.   
     
     
         24 . The method of  claim 23 , wherein the respective temperature sensors and valve for each respective coil are coupled to a controller in communication therewith, the controller performing the measuring and regulating steps for each respective coil. 
     
     
         25 . The method of  claim 24 , wherein the coolant is provided by a coolant system coupled to the respective inlet and outlet of each respective coil and the controller varies the desired coolant temperature in each respective coil based on coolant system operational parameters. 
     
     
         26 . The method of  claim 23 , comprising providing an adjustable valve flow regulator coupled to the coolant coil at each respective inlet and outlet and the regulating step is performed by at least one of the adjustable valves. 
     
     
         27 . The method of  claim 20  further comprising providing a coolant flow bypass between the coolant coil inlet and outlet and selectively recirculating coolant within the coolant coil with the bypass. 
     
     
         28 . The method of  claim 27  further comprising providing a remote actuated valve in the bypass for said recirculating within the coolant coil. 
     
     
         29 . The system of  claim 12 , wherein the coolant coils are replaceable while preserving the original exhaust flue with related connection flanges and the manifolds. 
     
     
         30 . A method for refurbishing the system of  claim 12 , comprising:
 disconnecting the coolant coils from the headers;   removing the coils from the exhaust flue;   installing new coolant coils about the existing exhaust flue; and   reconnecting the headers to the new coolant coils.   
     
     
         31 . An exhaust duct cooling system, comprising:
 an exhaust flue defining a interior cavity for passage of exhaust gas there through along an axial dimension thereof;   a coolant coil disposed about the flue for thermal communication with exhaust gas, the coil having a helical profile extending along the flue axial dimension, an interior lumen there through for passage of coolant, and a respective inlet and outlet for respective intake and discharge of coolant.   
     
     
         32 . The system of  claim 31 , wherein: the coolant coil helical winding profile has an inside diameter of 63-87 inches; the coolant coil has 2-N zone coil circuits; the coils are constructed of pipe selected from the group consisting of 2 inch pipe schedule  80 , 2 inch pipe schedule  160 , 2.5 inch pipe schedule  80 , 2.5 inch pipe schedule  80 , 2.5 inch pipe schedule  160 , 3 inch pipe schedule  40 , and 3 inch pipe schedule  80 ; and each coil circuit has an internal surface area of 43-76 square feet. 
     
     
         33 . The system of  claim 32  wherein the coolant coil has 2-9 zone coil circuits. 
     
     
         34 . The system of  claim 5  further comprising a coolant flow bypass between each coolant coil inlet and outlet, for selectively recirculating coolant.