SU1702107A1 - Tubular recuperator - Google Patents

Abstract

The invention is related to the field of heat exchange technology and can be used for high-temperature heating of air by utilizing the heat of waste combustion products of industrial furnaces. The aim of the invention is to increase reliability and efficiency by intensifying jet naipeea. The holes on the inner tube of the element are made uniformly along the generatrix, but unevenly around the circumference - about the frontal zone bounded by angles of ± 50 ° & for corridor location or ± 75 ° for the chess arrangement, and in the feeding area for both cases 150-210 °. The area of the holes on the inner tube Z f0 is determined from the inequality 0.33 FK 2 f0 0 625 G ,,. Here G is the living section of the annular channel between the pipes. FB - live section of the inner tube 3 Cf f-ly, 4 ill., 2 tabl

Description

The invention relates to the design of tubular heat exchangers for high-temperature heating of air by utilizing the heat of exhaust combustion products of industrial furnaces and can be used in heating and smelting furnaces of the engineering industry and metallurgy.

The purpose of the invention is to increase reliability and efficiency by intensifying jet heat exchange.

Fig 1 shows a tubular heat exchanger with a corridor arrangement of heat exchange elements, a longitudinal section; in fig. 2 shows section A-A in FIG. one; in fig. 3 - heat exchange element, longitudinal section; in fig. 4 - the same cross section.

A recuperator installed across the smoke line contains collectors of cold 1 and heated 2 air with corresponding connections for supplying 3 and exhausting 4 air. The collectors are attached to the tube plates 5 and 6. The recuperator is placed in the flue 7.

Heat exchanging elements 8 are fixed to the tube plates on both sides. The axes of which are parallel to each other. The heat exchange element is made of 9 external and 10 perforated pipes arranged internally. Holes 11 are evenly distributed along the generatrix and irregularly around the circumference in sectors bordering the frontal and stern zone. outer tube. The sectors are limited by angles in the frontal zone of p / ± 50 ° for the corridor beam and ipn ± 75 ° for the chess beam, and in the feeding zone in both cases y - 150-210 ° (for the positive reference angle of the so-called frontal critical the point where (p 0). For intensive work of the jet heat exchange element, it is necessary to observe a certain ratio of cross-sections of the outer FK inner tube Fn of the perforation area. 2 f0

k / i

WITH

vl

iS

-

About vj

0.33FK 2 f0 0.625FR

)

Experiments have shown that the holes must be completed within the specified sectors, otherwise the heat sink will decrease (Table 1).

From tab. 1, it can be concluded that outside the corners the heat sink is reduced by 50%.

Heat-hydrodynamic irregularity around the perimeter of the cross-flow pipe by flue gases is due to the presence of separation and mixing of the coolant. This leads to overheating of the frontal and aft zones. Known solutions, when the holes are made uniformly around the circumference, do not eliminate the unevenness. The proposed heat exchanger, in which holes are made within the frontal and aft zones, eliminates unevenness and thereby eliminates overheating of these sections. The thermal stability and durability of the heat exchange elements are increased.

Experiments were carried out on an experimental recuperator. In it, the geometrical parameters are selected in accordance with the condition of option 1 and option 2.

In tab. 2, the experimental data are compared with the indicators of the base object.

From the analysis of table. 2 it follows that one of the main indicators is to get warm from a unit. The heating surface q. So in the proposed recuperator q 77000 W / m2, which is 10% higher than in the base q 70000 6g / m2. This is due to the irrational choice of design parameters. So, 1l of base heat exchanger the ratio (1) is not observed

2.,

In this case, Z f0 0.625Fa, i.e. The internal section FB is smaller than the uniform distribution of air through the holes. Therefore, part of the heat exchange surface has less heat removal. In the proposed recuperator, 2 fo 0.625Fe, which allows to intensify the heat exchange and heat the air to a higher temperature (280 ° C) as compared to the base temperature (230 ° C) (option 1). The recovery rate in the proposed recuperator is 17.8% compared with 14.6% in the base. The data (variant 2) is also given here, provided that the geometrical parameters are chosen arbitrarily without taking into account relation (1). Therefore, the efficiency here is lower (13.3%) and the air heating is less than the baseline (210 ° C).

Tubular heat exchanger works as follows.

In the chimney, flue gases transfer heat to the heat exchange elements 8. Cold air is fed through pipe 3 into the collector 1 and into the internal pipes 10. Then the air is fed through holes 11 located circumferentially within the sectors defined by the angles specified in Table 1 to the internal surface of the external pipe 9 The passage through the annular gap, the heated air is collected in the manifold 2 and 4 through the pipe 4 leaves the heat exchanger.

Economic efficiency can be estimated using the data table. 2. More

high heating at 50 ° C saves up to 5% of fuel.

Claims (1)

The formula is invented and 1. Tubular heat exchanger containing transversely placed in smoke canene heat exchange elements in the form of coaxially mounted pipes, the inner ones of which are evenly along the length are perforated with outlets and connected to the flow channel, and the outer tubes are connected to an exhaust air manifold, characterized in that, in order to increase the reliability and efficiency of the OSG, and by intensifying the jet heat exchange, the outlet openings in each inner pipe are arranged in groups shifted around the circumference of the pipe, respectively, to no6oBOMv and rear in relation to the flue flow gas pipe sections. 2 A recuperator according to claim 1, so that it is with the corridor arrangement of heat exchange elements of the group of openings of the front and rear sections of the inner tube located in the zone bounded relative to the vertical by angles of ± 50 ° and + 150-210 ° 3. Pop-1 recuperator characterized in that with the staggered arrangement of the heat exchange elements of the group of openings of the front and rear sections of the inner pipe are placed in an area limited relative to the vertical by angles of ± 75 ° and + 150-210 °. 4. The recuperator on PP. 1-3, characterized in that the total area of the exhaust the openings of each inner tube satisfies the ratio 0.33 F If0 0.625Fe, where FK is the living section of the annular channel between the inner and outer tubes; FB is the living section of the inner pipe / f. Table 1 Zarmaig  12 Indicator Heating surface R. Diametho holes do. Air consumption V, Refinishing / R. Heat flow q, Air heating At, Recovery rate (Efficiency of the heat exchanger). Total surface holes 2 f3, Parameter 0.33 RC. Parameter 0.625 Pb. Table 2 city / Location chess corridor FIG. 2 HOYA. Air Naer. yozdu