U-shaped seal and method for use in cement plants
A method to thermally convert alternative fuels within a loop seal reactor by utilizing preheated/calcined cement meal as the heat source within which alternative fuels are immersed, subjected to drying, pyrolysis and subsequently charred, and an apparatus utilized to practice such method.
1. An apparatus for the heat treatment of solid combustible fuel comprising a hollow tubular structure having at least two substantially vertically extending hollow conduits comprising a first conduit adapted to have particulate material pass downward there through and a second conduit adapted to have particulate material pass upward there through, with each of the first and second conduits having a lower end, with each lower end attached to opposite ends of a bottom hollow third conduit that is adapted to have particulate material pass there through from the lower end of the first conduit to lower end of the second conduit, wherein the tubular structure further comprises a means to direct a pulsed gas upward from beneath the third conduit into the interior of at least one of the vertically extending conduits for a duration ranging from about 10 to about 200 ms, with an amplitude ranging from about 0.2 to about 5 bar and a frequency ranging from about 0.1 to about 10 Hz; the pulsed gas being configured to promote localized fluidization of the particulate material.
2. The apparatus of claim 1 wherein the third conduit is a straight conduit that extends at a downward slope from the lower end of the first conduit to the lower end of the second conduit.
3. The apparatus of claim 1 wherein the third conduit further comprises means for segregating heavy objects in a bottom part of the third conduit.
4. The apparatus according to claim 1 wherein the apparatus further comprises a calciner for calcining cement meal that is provided to the hollow tubular structure and for receiving charred combustible waste from the hollow tubular structure.
5. A method for the heat treatment of combustible waste during a process for the manufacture of cement clinker where cement raw meal is preheated and calcined in a preheater with a calciner, burned into clinker in a kiln and cooled in a subsequent clinker cooler, wherein the waste is subjected to heat treatment in a separate compartment having a material inlet and material outlet wherein the waste is inserted into the compartment and immersed in hot cement meal extracted from the cement clinker manufacturing process, and while so immersed the combustible waste is subjected to drying and pyrolysis, and resulting charring while moving, along with the hot cement meal, through the compartment from the material inlet to the material outlet from which the charred waste and the hot cement meal are delivered to the calciner or the kiln.
6. The method according to claim 5 wherein the material inlet and material outlet of the compartment are sealed off from receiving process gas from the cement manufacturing process.
7. The method according to claim 5 wherein at least some of the cement meal has been calcined, and wherein heat is generated within the compartment by subjecting such calcined hot cement meal to exothermic recarbonization as a result of being reacted with carbon dioxide gas released during the pyrolysis of the combustible waste.
8. The method according to claim 5 wherein the combustible waste inserted into the compartment is municipal waste.
9. The method according to claim 5 wherein the gases produced during the waste heat treatment method are further utilized in the cement making process.
10. The method according to claim 5 wherein at least some the gases produced during the waste heat treatment method are combined with kiln exhaust gases to reduce NOx in the cement manufacturing process.
11. The method according to claim 5 wherein at least some the gases produced during the waste heat treatment method are further utilized in the rotary kiln burner.
12. The method according to claim 5 wherein a pulsed gas is inserted into the compartment to facilitate the movement of the combustible waste and the cement meal from the material inlet to the material outlet.
13. The method according to claim 5 wherein at least some of the hot cement meal is extracted from the preheater.
14. The method according to claim 5 wherein the charred waste and the hot cement meal are delivered only to the calciner.
15. The method according to claim 5 wherein the gases produced during the waste heat treatment method are further utilized in a process to make combustible gases.