CN2716789Y

CN2716789Y - An improved air preheater

Info

Publication number: CN2716789Y
Application number: CN 200420031710
Authority: CN
Inventors: 陈世醒; 储刚; 陈文艺; 丁洪生; 赵亮; 张振华; 金子明; 翟杰
Original assignee: Liaoning Shihua University
Current assignee: Liaoning Shihua University
Priority date: 2004-05-21
Filing date: 2004-05-21
Publication date: 2005-08-10
Anticipated expiration: 2014-05-21

Abstract

The utility model relates to an improved air pre-heater which is composed of a fume inlet, a fume outlet, an air inlet, an air outlet, a fume box, an air collecting box and a main box body, wherein the main box body is provided with a heat conductive pipe of which the outer wall is provided with a plurality of fins which have two different heights and are arranged in a high and low mode. The improved fins can aggravate the disturbance of the fume, enlarge the convective heat conductive coefficient of the fume and the fins, and reduce the sedimentation and the erosion of fume spot. The heat conductive pipe is provided with turbolator insets with different length or sectional arrangement. Turbolators with different length or sectional arrangement can greatly reduce the flow resistance of air when the heat conduction in the pipe is enhanced, and the heat exchange of the fume and the air are strengthened to the maximum.

Description

A kind of modified air preheater

One, technical field

The utility model relates to a kind of air preheater that is widely used on industrial circle heating furnaces such as petrochemical industry, metallurgy, the energy and the Industrial Boiler.

Two, background technology

Extensively adopt air preheater to reclaim fume afterheat on petrochemical heating furnace, industry and the civil boiler, to improve the thermal efficiency of heating furnace.Because the convective heat-transfer coefficient of two side liquids is all less when flue gas and air heat exchange, strengthen therefore that gas-gas heat exchange must make in the pipe, the outer diabatic process of pipe is strengthened simultaneously.Add fin at fixing light pipe and can increase heat transfer area, in pipe, add the effective way that turbolator is the reinforcement intraductal heat transfer.Still there is the improved place of some needs in existing turbolator finned tube air preheater: in pipe, the isometric idea of traditional turbolator and heat-transfer pipe is challenged: according to hydrodynamics and thermal conduction study, under the situation of complete turbulent flow, if flow velocity increases and is twice, then convective heat-transfer coefficient increases 74% in the pipe, but meanwhile heat transfer resistance increases 300%! So how when increasing convective heat-transfer coefficient, to reduce the amplification of pressure drop, become an important starting point of the present utility model as far as possible.Outside pipe because the flow velocity of flue gas is lower, the disturbance on flue gas and finned tube surface not clearly, and in order to increase heat transfer area, the spacing all very little (2～5mm) of common fin.Etc. highly dense fin outer rim very fast " quasi-plane " state that formed under the erosion of crock, cause the crock deposition, thermal resistance increases, and the convection heat transfer' heat-transfer by convection effect between flue gas and fin worsens.How destroying fin outer rim this " quasi-plane " state, is another important thinking of the present utility model.

Three, summary of the invention

The purpose of this utility model is in order to solve the deficiencies in the prior art, a kind of modified air preheater that can improve heat transfer coefficient, reduce air flow resistance to be provided.The technical solution adopted in the utility model is: a kind of modified air preheater, form by the heat-transfer pipe in smoke inlet, exhanst gas outlet, air intake, air outlet slit, smoke box, plenum chamber, main box and the main box, be embedded with a lot of fins on the heat-transfer pipe outer wall, for the outer convection heat transfer' heat-transfer by convection of enhanced tube, high and low alternately on heat-transfer pipe with the circular fin of two kinds of differing heights (diameter), replace the fin of original single height (same diameter).This high and low alternate fin the time very easily produces second-disturbing flow when flue gas flows through its surface straggly, attenuate as the thickness of the viscous flow bottom of main heat transfer resistance, suppressed the formation speed of flue gas dirt, strengthened the convection heat transfer' heat-transfer by convection between flue gas and fin.

In pipe, can select turbolator for use less than heat-transfer pipe length according to the rerum natura of air and flow regime.By after the turbolator, the secondary circulation that powerful inertia produced can make screw be extended to blank space end in the pipe, has both reduced resistance, and heat-transfer effect is strengthened in the flue gas rotation.Experimental results show that: at complete turbulent region, turbolator length and heat-transfer pipe length ratio are good 0.5～0.75.

Also can adopt segmentation turbolator structure according to air flow condition and rerum natura.Be about to whole turbolator and be divided into plurality of sections, middle continuous with steel wire.Like this, air hockets by the screw action of turbolator section and the secondary circulation that produces in blank space, and the interior strengthening heat transfer of pipe is continued.

Four, description of drawings

Fig. 1 is the utility model structural representation;

Fig. 2 is a segmentation turbolator fin tube structure schematic diagram.

Five, the specific embodiment

The utility model is made up of the heat-transfer pipe 1 in smoke inlet 5, exhanst gas outlet 6, air intake 7, air outlet slit 8, smoke box 9, plenum chamber 10, main box 11 and the main body case 11, the stereoscopic air heat exchange of main tank required or 1 or 2 numbers of tube passes adopt single, double body structure, determine the various parameters of air preheater then according to the technological design result.In general, can consider two-tube-pass when the inner air tube flow velocity during greater than 10 meter per seconds, promptly the preheater main box is divided into two, otherwise adopts the single tube journey.Fin 2 on the heat-transfer pipe 1 has two kinds of differing heights, adopts high and low fin alternately, the desirable 3～5mm of high and low fin height difference.

Adopt turbolator augmentation of heat transfer technology in the pipe, fibrous root is selected turbolator 3 versions and other parameters according to the rerum natura of air and flow regime: when air flows when being in complete turbulence state, can adopt whole section turbolator of different length, turbolator 3 is 0.5～0.75 with heat-transfer pipe 1 length than optimum range, increase with reynolds number Re, the length of turbolator can correspondingly reduce; When air is in general turbulence state, can select segmentation turbolator structure for use, be about to turbolator 3 and be divided into plurality of sections, middle continuous with steel wire 4, turbolator compares L/L with the length of steel wire ₀Be 1.0～2.0, turbolator segmentation ratio should increase with Re and reduce.

In order to reach the purpose of destroying the viscous flow bottom, reducing heat transfer resistance, the turbolator tube wall of should trying one's best, and do not influence installation, rule of thumb, get its width e=(d usually _i-1) mm (di is a bore).

Turbolator can be inserted in the pipe with the traction method, in porch, turbolator upstream with steel bar or turbolator self is made "-" font " fix " at pipe end.So the installation method had both played the purpose that prevents the turbolator slippage, can make things convenient for the cleaning in turbolator and the pipe again.

Claims

1, a kind of modified air preheater, form by the heat-transfer pipe (1) in smoke inlet (5), exhanst gas outlet (6), air intake (7), air outlet slit (8), smoke box (9), plenum chamber (10), main box (11) and the main box (11), on heat-transfer pipe (1) outer wall a lot of fins (2) are arranged, it is characterized in that: these fins (2) have two kinds of differing heights, and alternately high and low.

2, a kind of modified air preheater according to claim 1 is characterized in that: the fin (2) on heat-transfer pipe (1) outer wall is for alternately high and low, and high and low fin height difference is 3～5mm.