Heat exchange – Regenerator – Checker brick structure
Patent
1994-05-27
1996-01-09
Flanigan, Allen J.
Heat exchange
Regenerator
Checker brick structure
165 8, 261 89, 261146, 261153, F23L 1502
Patent
active
054821088
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for achieving an optimal energy exchange in regenerative heat exchange between the combustion air and precooled, wet flue gases from a cooling device.
When flue gases containing water vapour are cooled down to temperatures under their dew point, the water vapour can condense and the condensation heat be recovered. A further drop in temperature is possible by a regenerative heat exchange between the combustion air and the precooled, wet flue gases, further water vapour being condensed on the fume side and being vaporized on the combustion air side. As the combustion air simultaneously with being heated is wetted, an essential part of the energy can be transferred from the flue gases to the combustion air. The transferable energy amount, however, is limited by the fume side condensation being achieved during the regenerative heat exchange which does not sufficiently correspond to the combustion air side vaporization capability.
The invention has as an object in a simple way to achieve an optimal energy exchange for the method mentioned above.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved in that the surfaces of a regenerative heat exchanger's heat exchanging elements on the flue gas are sprinkled with water in such a way that a water layer is formed on the heat exchanger element surfaces to such a degree that the element surfaces during their whole stay on the air side are substantially 100 percent covered with water. Without this water being added the heat transfer element surfaces dry up when passing the air side. The efficiency of this procedure in comparison with the method according to the invention appears from the following description of an example, according to which an increase of energy in the combustion air is achieved with 12.6 percent by the method of the present invention.
PREFERRED EMBODIMENT
According to a simple especially preferred development of the invention, the cooling device for the flue gas precooling is placed on top of the heat exchanger flue gas side, where the flue gases are led down into the heat exchanger in such a way that the condensation water formed in the cooling device can flow and/or drip down onto the heat exchanger elements. Consequently it is easy to achieve a temperature of the supplied water which is substantially equal to or somewhat higher than the flue gas temperature at the heat exchanger inlet which is of importance for the heat exchange.
DESCRIPTION OF THE DRAWINGS
The invention will be explained in detail in the following in connection with the attached drawing showing schematically as an example a heat exchanger with devices illustrating the method according to the invention, where
FIG. 1 is showing a longitudinal section along line I--I in FIG. 2 and
FIG. 2 a cross section along line II--II in FIG. 1.
In the drawing a rotatable, regenerative heat exchanger already known in the art is shown comprising a rotor 1 rotatably supported in a casing 2 with inlet channels 3, 4 for gases and air, respectively, and outlet channels 5, 6 for gases and air, respectively, as well as upper and lower section plates 7 and 8, respectively, dividing the air preheater into a gas side and an air side 9 and 10, respectively, covering each 165 degrees of the total circumference.
The rotor 1 is provided with radial walls 11 dividing the rotor into a number of sections 12 being occupied by heat exchanger elements 13. These are air permeable in the air and the gas flow directions and consist of corrosion resistant material.
In the gas inlet channel 3 a cooler 15 is placed which is connected to e.g. a return water pipe for district heating and cools the flue gases down to a temperature under their water dew point. Thus, the water is condensed mid flows directly or by means of a trench down onto the heat exchanger elements 13 of the rotor 1, the surfaces of which are performing the condensation occurring directly on the element surfaces and are also being sprinkled with additi
REFERENCES:
patent: 2843217 (1958-07-01), Von Linde
patent: 3148665 (1964-09-01), Switzer, Jr.
patent: 4287938 (1981-09-01), Lagerquist et al.
patent: 4452180 (1984-06-01), Hassan
patent: 4497361 (1985-02-01), Hajicek
patent: 4799941 (1989-01-01), Westermark
patent: 4909190 (1990-03-01), Finch
Essle Stefan
Sangfors Bo
Flanigan Allen J.
Svenska Rotor Maskiner AB
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