Annealing furnace cooling and purging system and method
In a method and system for an improved annealing furnace cooling and purging, atmosphere injection jets are provided in close proximity to a bottom of a tray carrying a lamination product in a cooling section. Atmospheric extraction tubes are also provided extracting atmosphere which is delivered to a high temperature variable speed fan which then outputs at a pressure side atmosphere to tubes having the injection jets. The system may be retrofit into an existing annealing furnace already having water cooled finned tubes and a recirculation fan in the cooling section. Cooling water tubes and a recirculating fan may also be provided in a purge vestibule located after an output from the cooling section for additional cooling.
1. A method for processing laminations in an annealing furnace, comprising the steps of:
providing a high heat section followed by a cooling section, a purge vestibule, and an oxidation section;
providing a conveyor running from the high heat section through the cooling section, purge vestibule and oxidation section;
providing a plurality of trays on the conveyor carrying the laminations;
in the cooling section providing a plurality of atmosphere injection tubes with each tube having a plurality of atmosphere injection jets blowing directly onto the trays on the conveyor;
in the cooling section extracting atmosphere in a region of the conveyor; and
with a fan circulating the extracted atmosphere back to the atmosphere jets.
2. A method of claim 1 including the step of using at least one cooling tube having a cooling fluid flowing therein to cool the extracted atmosphere fed back to the atmosphere jets.
3. A method of claim 1 including the step of providing at least one cooling tube in a chamber of the cooling section carrying a cooling fluid to further cool atmosphere in the chamber.
4. A method of claim 1 including the further step of providing a recirculating fan in a chamber of the cooling section to recirculate atmosphere in the chamber.
5. A method of claim 1 including the step of providing the atmosphere jets sufficiently close to the laminations in the trays to disrupt a boundary layer of atmosphere at a surface of the laminations.
6. A method of claim 1 including the step of sensing a temperature of the laminations exiting the cooling section to control a speed of said fan circulating the extracted atmosphere.
7. A method of claim 1 including the step of providing an infra-red pyrometer to measure a temperature of the laminations exiting the cooling section.
8. A method of claim 1 including the step of sensing a temperature of the laminations in the purge vestibule which have exited the cooling section.
9. A method of claim 1 including the step of providing at least one cooling tube in the purge vestibule.
10. A method of claim 1 including the step of providing a recirculation fan in the purge vestibule.
11. A method of claim 1 including adjusting a velocity of the atmosphere jets.
12. A method of claim 1 wherein based on a signal from a pyrometer measuring lamination temperature, employing a computer based algorithm to provide from a computer a control signal to a variable speed motor for the fan to provide a variable rate of heat transfer by controlling the fan.
13. A method of claim 1 including the step of placing the atmosphere jets in close proximity to the laminations being annealed where the injection jets are to a side of the laminations.
14. A method according to claim 1 including the step of providing the atmosphere jets above the laminations.
15. A method for processing product in a furnace, comprising the steps of:
providing a high heat section followed by a cooling section;
providing a conveyor running from the high heat section through the cooling section;
providing the product on the conveyor;
in the cooling section providing a plurality of atmosphere injection tubes with each tube having a plurality of atmosphere jets close to the product on the conveyor;
in the cooling section extracting atmosphere in a region of the conveyor; and
with a fan circulating the extracted atmosphere back to the atmosphere jets.
16. A method of claim 15 including the step of providing the product as continuous strip.
17. A method of claim 15 including the step of providing the product as laminations and regulating a speed of the fan recirculating the extracted atmosphere so that a temperature of the laminations exiting from the cooling section is between 600 and 1000° F.
18. A method for retro-fitting an existing annealing furnace for laminations, said existing furnace having a heating section followed by a cooling section, a purge vestibule, and an oxidation section, and a conveyor from the heating section through the cooling section, purge vestibule and oxidation section, comprising the steps of:
installing in the existing furnace cooling section a plurality of atmosphere injection tubes, each tube having a plurality of atmosphere injection jets, the atmosphere injection tubes being installed adjacent the conveyor in a position to blow the cooled atmosphere directly on trays carrying the laminations on the conveyor and to cause turbulence to disrupt a boundary layer which may surround the laminations in the trays;
also installing at least one atmosphere extraction tubes in the cooling section; and
installing a fan which receives extracted atmosphere from said extraction tube at an input side and outputs the extracted atmosphere to said atmosphere injection jets.
19. A method of claim 18 including the step of providing a variable speed motor for the fan and a control for that motor which senses a temperature of laminations exiting from the cooling section.
20. A method of claim 18 including the step of shortening the cooling section and lengthening the heating section when retro-fitting the furnace.