Distillation: apparatus – Apparatus – Systems
Patent
1991-11-22
1993-11-09
Woodard, Joye L.
Distillation: apparatus
Apparatus
Systems
202141, 202144, 202151, C10B 516, C10B 2118
Patent
active
052599329
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention pertains to a heating system for regenerative coke oven batteries that can be heated with rich gas and/or lean gas or mixed gas, with vertical flues cooperating in pairs, the flues being connectable to regenerators for preheating the air and, in the case of lean gas operation, also connectable with regenerators for preheating the lean gas or mixed gas, high and low combustion stages, as well as with an internal flue gas return at levels of the flue base.
BACKGROUND OF THE INVENTION
A heating system with flues cooperating in pairs, air supply stages located high and low, as well as a flue gas return at the level of the flue base, has been known from European Patent Application No. 0,183,908. In these only two air supply stages over the height of the flue, the supply of air and gas at the base of each flue forms the first stage, and the supply via hollow communicating channels and discharge slots, located at the same height for both adjacent flues, forms the second stage. Heating with only two air supply stages is not sufficient for optimal combustion and for minimizing the NO.sub.x formation in coke ovens with a chamber height exceeding, e.g., 4 m.
SUMMARY AND OBJECTS OF THE INVENTION
The primary object of the heating system according to the present invention is to achieve uniform heating of the oven chambers with the smallest possible amount of NO.sub.x formation even in the case of a greater oven height, wherein optimal control of each individual combustion stage is possible even during ongoing operation, especially after a change from one type of gas to another.
This new heating system is characterized especially by the fact that the amount of the combustion air supplied at three or more levels can be adjusted from the outside for each individual stage even during ongoing operation. The three-stage or more than three-stage air supply permits both multistage combustion or heating of the oven chambers over the height and--to reduce the nitrogen oxide formation--also substoichiometric combustion in the lower combustion zones of the flue, as well as lower flame temperatures. At the same time, a further possibility for reducing the nitrogen oxide emission is fully utilized via flue gas return, besides the stepwise admission of the combustion air.
Besides the internal return with the so-called circulating flow openings, the return of relatively cold flue gases from the smokestack canal and mixing it with the combustion air is suggested according to the present invention as an external flue gas return. Especially the returned flue gas can be mixed with the combustion air and heated to the preheating temperature in the regenerators.
To achieve optimal combustion control in the ascending flues, it is suggested according to the present invention that the rich gas nozzles to which gas is admitted during one heating period be arranged in the longitudinal direction of the oven in one plane in the vicinity of one traveling wall in front of the corresponding circulating flow openings, and the rich gas nozzles to which gas is admitted during the other heating phase be also arranged in the longitudinal direction of the oven in one plane in the vicinity of the other traveling wall in front of the corresponding circulating flow openings.
It was also found to be favorable to arrange only one discharge opening, which is connected to a regenerator carrying lean gas or mixed gas, at the flue base in each flue, to supply the weak gas or mixed gas into each flue. In view of the fact that this gas usually burns with a longer flame, sufficient heating of the oven charge can be achieved with this exclusive gas supply at the flue base even in the case of taller chambers. The discharge openings at the flue base for both the air and optionally for the lean gas or mixed gas are preferably arranged exactly in the middle of the flue between the two corresponding traveling walls.
As an advantageous embodiment, it is suggested for a heating system of a twin flue type that a hollow communi
REFERENCES:
patent: 2845385 (1958-07-01), Van Ackeren
patent: 4061544 (1977-12-01), Van Ackeren et al.
patent: 4704195 (1987-11-01), Janicka et al.
patent: 5017270 (1991-05-01), Janicka et al.
Blase Manfred
Durselen Heinz
Hoitz Joachim
Kochanski Ulrich
Meyer Gunther
Didier OFU Engineering GmbH
Krupp Koppers GmbH
Still Otto GmbH
Woodard Joye L.
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