BG64570B1 - Heat exchanger for the recuperation of flue gas heat - Google Patents

Abstract

The heat-exchanger has higher heat exchanging speed, ensuring even distribution of the liquid phase along the cross section of the ducts along which it runs, and the duct section immediately after the inlet and before the outlets of the liquid is reduced from 1.5 to 4 times. The heat exchange has vertical housing (1) in which interconnected plates (10) are mounted. Plates (10) form parallel canals for running of the gas and liquid streams, additionally connected two by two to flat bodies (2). In the lower and uppermost part the flat bodies (2) are connected to an inlet collector (6) for the liquid, and to an outlet collector (4), respectively. Collectors (6, 4) have the form of boxes and having an inlet (5) and outlet (3) pipe connection for supplying and discharging the liquid. Immediately under collectors (6 and 4), in one of the two heat-exchange plates (10), to their inner sides, indentures (8) having permanent cross-section are horizontally stamped.

Description

Technical field

The invention relates to a heat exchanger for the utilization of flue gas heat. It can be used in the recovery of heat and other waste gases, as well as in the cooling of gases in the chemical industry and related industries.

BACKGROUND OF THE INVENTION

A heat exchanger is known for utilizing the heat of flue gases to heat liquids [1], consisting of interconnected heat exchange panels that form parallel channels for flow. Moreover, the gas flow channels are longer than the gas flow channels. Both gas and liquid ducts are connected to the inlet and outlet of the flows by collectors. The fluid reservoirs are enclosed at the top and bottom by the bars through which the channels pass. On the side they are bounded by a quadrangular housing. The housing of the device is also quadrangular.

The design of the known heat exchanger does not allow a uniform distribution of the liquid phase in the cross section of the channels for its movement. This, in turn, results in a difference in the velocities and temperatures of the flow along the width of the channels for the fluid. Different speeds lead to a decrease in the average heat transfer coefficient, and different speeds to a decrease in the average temperature difference in the apparatus.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a heat exchanger for the utilization of flue gas heat, whereby the rate of heat exchange is increased by providing a uniform distribution of the liquid phase across the channels along which it travels.

The problem is solved by means of a heat exchanger for utilizing the heat of flue gases for heating mainly liquids, including a vertical housing, in which heat exchange plates are formed interconnected, forming parallel channels for the flow, with all gas channels being the same and the liquids are also identical with each other, the channels for both the gas and the fluid being connected at the inlet and outlet respectively by gas ducts and manifolds, characterized in that the heat exchange plates are connected to two in parallelepiped-shaped flat bodies, the width of the inner space of the flat bodies being supported by inwardly extruded in it, in the wide walls by local projections, preferably welded with spot welding, and the flat bodies are connected to the inlet manifold. the fluid, respectively, with an outlet manifold, the collectors being shaped as boxes connected to an inlet nozzle, respectively with an outlet nozzle, and directly above the inlet manifold and directly below the outlet manifold, preferably in one of the two heat exchangers the plates forming the flat bodies are stamped inwardly to the parallelepiped horizontal recesses with a constant cross-section, which narrow locally the corresponding horizontal cross-section of the flat bodies, reducing it from 1.5 to 4 times, whereby the flat bodies are supported by a grate which is preferably consists of rails located at the lower end of the heat exchanger and connected to the housing above the outlet duct, the gas flow channels being formed between the plates and the width being maintained by the distance plates.

According to one embodiment of the heat exchanger, the four narrow sides of the flat bodies are formed mainly by bending one of the heat exchanger plates. The two plates are mainly joined by welding.

According to a second embodiment of the heat exchanger, inclined corrugations are embossed in the walls of the heat exchange plates, between the horizontal recesses, for turbulence of the flows.

The advantage of the invention is that it provides a uniform distribution of the fluid between the heat exchange plates, which in turn leads to an increase in the effective mean temperature difference and to an increase in the average heat transfer coefficient. In this way, the heat exchange surface and the weight of the apparatus are reduced under the same initial conditions, or the amount of heat recovered is increased while maintaining the heat exchange surface.

Description of the attached figures

The invention is illustrated by the accompanying figures, of which:

Figure 1 is a side view of the heat exchanger;

FIG. 2 is a section through AA of FIG. 1;

Figure 3 is a view of a heat exchanger plate;

4 is a sectional view along B-B of FIG. 3;

5 is a cross-sectional view of a flat body of FIG. 1 in the area of the local projections 9, in the case of the embossing of the two heat transfer plates of the flat body;

6 is a cross-sectional view of a flat body of FIG. 1 in the area of the local projections 9, with the option of stamping only one of the two heat transfer plates 10 of the flat body 2;

7 is a view of a heat exchange plate on which corrugations are stamped.

Examples of carrying out the invention

The heat exchanger for utilizing the heat of flue gases for heating mainly liquids presented in Figures 1 to 7 is a counter-current apparatus. It has a vertical housing 1 in which heat exchange plates 10 are connected together. The plates 10 form parallel channels for the flow of gas and liquid. The gas channels 11 are identical to each other and are formed by means of spacers 12 welded to the heat exchange plates 10. The fluid channels are formed between the heat exchange plates 10, connected two by two in flat bodies 2 in the shape of a parallelepiped, and are also the same. with each other. The width of the inner space of the flat bodies 2 is held by the locally extruded 9 pressed in the heat transfer plates 10, welded by spot welding to the adjacent heat exchange plate 10. The flat bodies 2 are connected respectively at the bottom and at the top thereof. with an inlet manifold 6 for the fluid and an outlet manifold 4. The collectors 6,4 are shaped as boxes and have an inlet 5 and an outlet 3 nozzle respectively for supplying and removing the fluid from the heat exchanger. These boxes are connected to opposite walls of the heat exchanger. Immediately above the lower manifold 6 and immediately below the upper manifold 4, horizontal recesses 8, with a constant cross-section, are embossed into one of the two heat exchange plates 10 forming the flat bodies 2. These recesses reduce 2.5 times the local cross-section for the movement of the liquid phase in the channel of the flat bodies 2. The heat exchanger includes an inlet duct 14 and an outlet duct 15, between which the flat bodies 2 are supported by a grille 7 made of bars located at the lower end of the apparatus and connected to the housing 1 above the outlet duct 15. The gas flow channels 11 are formed between the plates 10. Their width is maintained by the distance plates 12.

According to one embodiment of the heat exchanger, as shown in FIG. 7, inclined corrugations 13 are embossed between the horizontal recesses 8 in the walls of the heat exchange plates 10.

The heat exchanger works as follows.

The water is fed through the nozzle 5 and falls into the inlet manifold 6. From there, through the openings in the walls of the flat bodies 2, it is distributed evenly in all bodies 2. Through the narrow section in the area of the lower horizontal recess 8, the liquid is distributed evenly throughout the section of the channels formed in the flat bodies 2 and is indirectly heated by the gas stream. The uniform distribution of the fluid is maintained up to the upper narrow section, in the region of the horizontal recess 8. Thereafter, through the channel formed between this narrow section and the upper end of the flat bodies 2, the heated fluid enters the outlet fluid collector 4. From there, nozzle 3, it is removed from the apparatus. The gas flow enters the upper part of the apparatus through the inlet duct 14, passes through the channels 11 formed between the flat bodies 2, cools and exits the apparatus through the outlet duct 15. When cooled below the dew temperature, water vapor condensing from it in the form of a film on the outer wall of the heat exchange plates 10. The resulting condensate 5 is evacuated and separated from the gas stream by known separators prior to the gas being released into the atmosphere.

Claims (3)

Claims 1. Heat exchanger for recovering heat from flue gases for heating mainly liquids, comprising a vertical housing in which heat exchange plates are connected interconnected to form parallel channels for flow, all gas channels being the same and the channels for the liquid also The gas and liquid channels are connected at the inlet and outlet respectively by gas ducts and manifolds, characterized in that the heat exchange plates (10) are connected two by two in a flat wire. a (2) in the form of a parallelepiped, the width of the inner space of the flat bodies (2) being supported by inwardly extruded walls, local projections (9), preferably welded with spot welding, and flat bodies ( 2) are connected to the inlet manifold for the fluid (6), respectively to the outlet manifold (4), the collectors (6 and 4) being shaped as boxes connected to the inlet nozzle (5), respectively to the outlet nozzle (3), and directly above the inlet manifold (6) and immediately below the outlet manifold (4), it is preferably in one of the two heat exchangers. bumper plates (10) forming the flat bodies (2) are stamped inwardly to the parallelepiped horizontal recesses (8) with a constant cross section that narrow locally the corresponding horizontal cross section of the flat bodies (2), reducing it from 1.5 to 4 times and in this case the flat bodies (2) are supported by a grate (7), which preferably consists of bars located at the lower end of the heat exchanger and connected to the housing (1) above the outlet duct (15), such as the gas flow channels (11) are formed between the plates (10) and their width is maintained by the distance plates nicks (12). A flue gas heat exchanger according to claim 1, characterized in that the four narrow sides of the flat bodies (2) are preferably formed by bending one of the heat exchange plates (10), the two plates being preferably connected by welding. 3. Flue gas heat exchanger according to claim 1 or 2, characterized in that inclined corrugations (13) are printed in the walls of the heat exchange plates (10) between the horizontal recesses (13) for turbulent flows.