CS257580B1 - Heat exchanger, especially for uneven input of heat transfer medium - Google Patents

Abstract

The exchanger solves the issue of reducing heat exchange surfaces and thus acquisition costs. Its essence lies in the fact that at least one dividing partition equipped with at least one closable opening is created between the heat exchange surfaces and the flue gas outlet.

Description

The invention relates to a heat exchanger, in particular for uneven power input of the heat transfer medium.

The waste heat of industrial fuel furnaces can be used directly in the primary process or as an energy source for secondary heating processes, domestic water heating, material drying for possible heating of operational buildings.

Most often waste heat is used for the technological process, especially for preheating of combustion media, ie fuel and especially combustion air. The advantage of this application is independence from other downstream operations and relatively simple construction. The disadvantage is the difficulty of regulation in connection with the course of the technological heat treatment, especially in the case of cyclically operating furnace aggregates, where the need of preheated combustion air in dependence on time is different from the output of heat transfer surfaces. Failure to observe the optimum fuel-to-air combustion ratio results in losses due to butt burns or, on the other hand, chimney losses.

The exchangers used up to now consist of heat transfer surfaces, the size of which is determined by sufficient heat output at a low temperature level of the exhaust gas. To meet the requirement that no part of the exchanger be cooled down to a temperature below the dew point, the exchanger is often too large, thus increasing the cost of the exchanger disproportionately.

If this requirement is not observed, condensation of water vapor occurs in some places, mostly at the outlet of the heat transfer medium, which causes corrosion of metallic materials, especially when heating with sulfur fuels. This significantly reduces the service life of the exchanger.

These disadvantages are avoided by the heat exchanger, in particular because of the uneven input of the heat transfer medium, according to the invention. This exchanger consists of heat transfer surfaces formed in the flue gas duct. The principle of the invention is that the exchanger is provided with at least one partition between the heat exchange surfaces and the flue gas outlet. The partition is then provided with at least one closable opening. In order to optimize the effects achieved, it is advantageous if one L-shaped partition is provided with a closable hole coaxial with the longitudinal axis of the exchanger in front of the heat transfer surfaces and the other partition is formed behind the heat exchange surfaces. From the viewpoint of controlling the operation of this exchanger, it is further advantageous if the closable opening actuator is connected via an evaluator to a thermocouple housed in the flue gas flow mixture in front of the heat transfer surfaces.

The advantage of the exchanger according to the invention is that it allows a reduction of the heat transfer surfaces and thus also the purchase costs while maintaining a long service life. By means of the solution according to the invention, existing exchangers can be easily adapted.

The invention is further described by way of example with reference to the drawing, which shows a diagram of an exchanger for uneven water vapor input.

The exchanger consists of a flue gas inlet 6 and a flue gas outlet 6 between which a flue gas channel 6 is formed.

It consists of 2 several rows of heat transfer surfaces 4, which consist of a tubular snake, and two L-shaped dividing partitions. Both of these dividing partitions 6 are coaxial with the longitudinal axis of the heat exchanger. One of these baffles 6 is formed in front of the heat transfer surfaces 6, the other behind these surfaces 6. The part of the partition 4 formed parallel to the flue gas channel 4 is oriented between the heat transfer surfaces 4. The closable aperture controller 6 is connected to a thermocouple (not shown) via an evaluator (not shown). The exchanger is divided into three sections £, 3, £ by means of dividing partitions.

With openings 8, these sections 8 to 8 will be divided in parallel, with closed openings 8 these sections will be divided in series. Parallel connection is advantageous especially at low temperature level of the exhaust gases, because due to the low velocity the heat transfer coefficient is low and the combustion gases do not cool below the dew point temperature. When the temperature increases with holes

9, the flow velocity and the heat transfer coefficient are increased, thereby increasing the heat transfer at the same size of the heat transfer surface.

The heat exchanger, especially for uneven power input of the heat transfer medium, can be used especially when utilizing waste heat from industrial furnaces.

Claims (3)

SUBJECT OF THE INVENTION A heat exchanger, in particular for an uneven power input of a heat transfer medium, consisting of heat transfer surfaces formed in the flue gas channel, characterized in that at least one partition (7) is formed between these heat transfer surfaces (6) and the flue gas outlet (5). provided with at least one closable opening (9). Heat exchanger according to claim 1, characterized in that one L-shaped partition (7) provided with a closable opening (9) coaxial with the longitudinal axis of the exchanger is formed in front of the heat transfer surfaces (6) and the other partition (7) is formed behind these heat transfer surfaces (6). Heat exchanger according to Claims 1, 2, characterized in that the controllable opening (9) is connected to the thermocouple via an evaluator.