SU1755011A1 - Recuperator - Google Patents

Abstract

Usage: mainly for air preheating with waste gases from industrial furnaces in the metallurgical industry. SUMMARY OF THE INVENTION: A recuperator consisting of flat screens formed by U-tubes 4 connected to supply and discharge headers 1 and 2 contains additional rows of tubes 5 located inside the screens at an angle of 45-90 °. to them, which makes it possible to use the volume of the heat exchanger inside the screens without increasing the dimensions. , 5 il. Airborne

Description

1

The invention relates to heat exchangers and can be used primarily for preheating air with flue gases in industrial furnaces in the metallurgical industry.

Metal cast iron-steel recuperators (thermoblocks) are known, which are a bundle of pipes of circular or oval cross-section, which are cast (armored) with cast iron.

The disadvantages of this design are the laboriousness of the exhaust, a relatively large mass of thermoblocks, a large clogging of the narrow smoke channels of the thermoblock, low efficiency and unsuitability for high temperature conditions.

Also known is the design of a metal needle heat exchanger, the main element of which is an oval-shaped cast-iron needle pipe in cross section with external and internal needles.

The disadvantages of this design are frequent cracking and burnout of pipes in heat exchangers, a large number of joints between pipe flanges, which leads to a significant decrease in the efficiency of operation of heat exchangers due to the leakage of part of the material

The closest to the proposed technical entity is a heat exchanger containing U-tubes connected to the inlet and outlet manifolds, located one inside the other with the formation of flat screens installed in a duct in parallel rows with the formation of an internal CAVITY between them.

A disadvantage of the known design of the heat exchanger is the relatively low heat transfer from the heating medium to the outer walls of the pipes, as well as from the inner walls of the pipes to the heated medium. This is due to the inability to use the volume of the heat exchanger inside the flat tube screens due to the inadmissibility of further reducing the minimum bend radius of the heat exchange tubes. (the pipe material, its dimensions and the technology of gyS at the factory determine the minimum bending radius of the pipes). As a result, the recuperator is not used effectively.

The purpose of the invention is to intensify heat transfer.

This goal is achieved by the fact that a heat exchanger containing U-shaped pipes located one inside the other with the formation of flat screens installed in a duct in parallel rows with the formation of an internal strip ™ between them,

It contains additional U-shaped tubes, each of which is connected to the supply and discharge manifolds and installed in the said cavity in a plane placed at an angle of 45-90 ° to the planes of the screens.

Figure 1 shows a tubular recuperator, side view; in Figures 2-4, section A-A in phi (.1 (variants are additional to a number of U-shaped tubes inside the Truss shirg}; Hd of Figure 5 - section B in Fig. 4,

The 1-section heat exchanger consists of a supply manifold 1, a discharge manifold 2, a tube plate 3, to which heat-insulated U-shaped tube 5, which make up tube screens, and an additional row of coarse 5, located inside the width at an angle a 45-90 ° to them.

The coefficients of each U-shaped pipe 5 in the additional rows are denoted by the same infr / g-y; 2 -2, 3 -3; 4 -4; 5-5; G-b T-T; 8-8.

The installation of an additional row of heat exchange tubes 5 under the weight of a - 45-90 ° to the planes of pipe screens allows us to use the volume of the heat exchanger inside the tr / hot screens without increasing the thrust ratio compared to the known

without any reduction in the minimum permissible bending radius of pipes. This provided air heating by 40-60 ° C higher compared to the known tubular recuperators 1 — the same production (dimensions and dimensions; radius

bending can not be less than the value determined by the technology

The lower limit of a- 45 ° of the angle of installation of dpatnitelnyh rads and heat exchanging tubes of a high angle, starting from the minimum radius

bending of U-shaped tubes, the smaller angle does not allow the installation of heat exchange tubes inside the tube screens,

The upper limit of a- 90 ° is chosen for the installation of an enutri of pipe screens as well as additional U-shaped pipes with a bend radius greater than the minimum radius.

Metal tubular heat exchanger works as follows. The recuperator is installed in the burs, through which exhaust fumes are flowing, washing the heat exchange pipes 4 and. The cold air passes through the inlet manifold 1, the heat exchange tubes 4 and 5, is heated in them and through the outlet manifold 2 enters the furnace burners

Example. The proposed device (for example, the variant of FIG. 2) can be implemented in a known recuperator having 88 U-shaped tubes with an outer diameter of 0 76 mm, a wall thickness of 4-5 mm, bending radii from 250 mm to 1125 mm. Pipe material: steel 15 x 25 T.

Additional rows of U-shaped tubes with a bend radius R 250 and R 340 are installed inside the tube screens (Fig. 2) at an angle to them (for example, 58 and 68 °). This increases the ratio of the heat exchange area of the heat exchanger to the volume of heated air without increasing the size of the heat exchanger, which causes an increase in air temperature by 40 ° -C ° C compared with the known recuperator.

The proposed device makes it possible to intensify the heat transfer from the heating medium to the heated medium, to improve the operation of the heating and thermal effects of increasing the temperature of heating the air in the recuperator, and to reduce the consumption of fuel supplied to the furnace.

Intensification of heat transfer from the inner walls of the pipes to the heated medium increases as the ratio of the surface of the heated pipes to the volume of the heated gas (air) washing the given surface increases.

Along with this, with the location of additional U-shaped pipes under

Aa

2

angle to the flow of exhaust gases creates conditions for additional turbulence in the flow of dima gases, which increases the heat transfer from the heating medium to the outer

pipe walls As a result of the intensification of heat transfer from the heating medium to the outer surface of the pipes and the intensification of heat transfer from the inner surface of the pipes to the heated medium, the heat transfer from the heating medium to the heated medium in the heat exchanger increases.

The economic effect of using the proposed device is achieved by increasing the temperature by heating

my environment at 40-60 ° C compared with the heated air in a tubular heat exchanger of known design.

Claims (1)

Invention Formula A recuperator containing U-shaped pipes connected to the inlet and outlet manifolds, located one in the loop with the other to form flat screens installed in a gas duct in parallel rows with the formation of an internal strip ™ between them, characterized in that, in order to intensify heat transfer, it contains additional U-branch pipes, each of which is connected to the inlet and outlet manifolds and adopted in the said cavity in a plane placed at an angle of 45-90 ° to the planes of the screens.  , Y Fm.z five H-4- + H - I - T Dymo8yep L-1-I-AND- -H- -t- H-4-4 gases  $ Jf Hi J ff tff Editor A. Ogar fl) wa5 Compiled by T, Nezeova. . Tehred M.MorgentalKorrektor T.Paly  / ha four WE air Ш2.Чг -f