Air preheater adopting wing streamline pipe

Abstract

The utility model relates to an air preheater adopting wing streamline pipes, and belongs to the technical field of heat exchange equipment. Comprising a shell, an air tube box, an air inlet, an air outlet, a flue gas inlet, a flue gas outlet, two wing streamline tube bundles and two tube plates. The air inlet and the air outlet are formed in the upper portion and the lower portion of the front wall of the shell respectively. The air pipe box is arranged on the rear wall of the shell; one tube plate is arranged at the air inlet; the other tube plate is arranged at the air outlet; each tube plate is correspondingly provided with one wing streamline tube bundle; the two wing streamline tube bundles are axially and horizontally arranged up and down; the inlet end of the upper wing streamline tube bundle is aligned with the air inlet, and the outlet end is butted with the air tube box; the inlet end of the lower wing streamline tube bundle is butted with the air tube box, and the outlet end is aligned with the air outlet; the flue gas inlet is formed in the bottom of the shell; the flue gas outlet is formed in the top of the shell; the utility model solves the problems of low heat exchange efficiency and large resistance in the prior art.

Description

TECHNICAL FIELD

[0001] The utility model belongs to heat exchange equipment technical field relates to an air preheater adopting airfoil streamline tube. BACKGROUND

[0002] Air preheater is important recovery equipment in industrial boiler and heating furnace, its function is to utilize flue gas waste heat to heat the air that is sent into the hearth, improves thermal efficiency, saves fuel, at present, the air preheater widely used in industry mainly has two kinds of tubular preheater and rotary preheater, wherein, tubular preheater is widely applied because of simple structure, convenient maintenance, the traditional tubular air preheater adopts regular pipe channel such as round pipe as heat exchange element, however, regular pipe channel such as round pipe has the following shortcomings:

[0003] (1) the heat exchange area in unit volume is small, and the heat exchange efficiency is not high;

[0004] (2) the airflow is easy to form stagnation zone on the outer wall of the round pipe, the resistance is large, and the heat transfer coefficient is reduced;

[0005] (3) there is a large dead zone when the round pipes are arranged, which reduces the compactness of the heat exchanger.

[0006] It is difficult to meet the needs of industrial production for high-efficiency, energy-saving and long-life air preheaters. SUMMARY

[0007] The utility model solves the technical problem of overcoming the prior art's shortcomings, and provides an air preheater using airfoil streamline tubes, which solves the problems of low heat exchange efficiency and high resistance in the prior art.

[0008] The technical solution of the utility model is as follows:

[0009] An air preheater using airfoil streamline tubes, comprising a shell, an air pipe box, an air inlet, an air outlet, a flue gas inlet, a flue gas outlet, two airfoil streamline tube bundles, and two tube plates.

[0010] The shell is a vertical rectangular shell structure, the air inlet is arranged above the front wall of the shell, the air outlet is arranged below the front wall of the shell, the air pipe box is arranged on the rear wall of the shell, one of the tube plates is arranged at the air inlet, the other tube plate is arranged at the air outlet, each tube plate is provided with one airfoil streamline tube bundle, the two airfoil streamline tube bundles are arranged axially and horizontally, the inlet end of the upper airfoil streamline tube bundle is aligned with the air inlet, and the outlet end is connected to the air pipe box, the inlet end of the lower airfoil streamline tube bundle is connected to the air pipe box, and the outlet end is aligned with the air outlet, the flue gas inlet is arranged at the bottom of the shell, and the flue gas outlet is arranged at the top of the shell.

[0011] In the air preheater with wing streamline tubes, the air inlet, the upper wing streamline tube bundle, the air tube box, the lower wing streamline tube bundle and the air outlet form a transverse U-shaped air flow channel.

[0012] In the air preheater with wing streamline tubes, the high-temperature flue gas enters the shell from the flue gas inlet, exchanges heat with the two wing streamline tube bundles in the shell cavity, heats the cold air flowing in the wing streamline tube bundle, and is discharged from the flue gas outlet.

[0013] In the air preheater with wing streamline tubes, the wing streamline tube bundle is composed of a plurality of wing-shaped cross-section heat exchange tubes; the plurality of wing-shaped cross-section heat exchange tubes are arranged in a staggered arrangement; the staggered distances of the center lines of the adjacent wing-shaped cross-section heat exchange tubes in the row and column are 20 mm and 40 mm, respectively.

[0014] In the air preheater with wing streamline tubes, the tube plate is a plate structure; one tube plate is installed above the front wall of the shell, and the other tube plate is installed below the front wall of the shell; the two tube plates seal the front wall of the shell; the tube plate is provided with through holes corresponding to the cross-sectional shape of the wing-shaped cross-section heat exchange tube, and the through holes are arranged in a staggered manner; the plurality of wing-shaped cross-section heat exchange tubes corresponding to the wing streamline tube bundle extend into the through holes; the cold air flows in the wing streamline tube bundle without mixing with the high-temperature flue gas.

[0015] In the air preheater with wing streamline tubes, the cross-sectional shape of the wing-shaped cross-section heat exchange tube is composed of a half-ellipse and two circular arcs; the half-ellipse is located at the bottom and opens upward; each opening sidewall of the half-ellipse is linearly connected with a circular arc; and the two circular arcs intersect to form a top pointed structure.

[0016] In the air preheater with wing streamline tubes, the curve equation of the half-ellipse is:

[0017] x 2 / 30 2 +y 2 / 7 2 =1

[0018] The curve equation of the circular arc is:

[0019] x 2 +y 2 =163 2 .

[0020] In the air preheater with wing streamline tube, the cross section shape of the wing-shaped cross section heat exchange tube is composed of a half ellipse, two circular arcs and an elliptical arc; the half ellipse is located at the bottom and opens upward; each opening sidewall of the half ellipse is linearly connected with one circular arc; the elliptical arc opens downward, and each opening sidewall of the elliptical arc is linearly connected with the top of one circular arc.

[0021] In the air preheater with wing streamline tube, the curve equation of the half ellipse is:

[0022] x 2 / 30 2 +y 2 / 7 2 =1

[0023] The curve equation of the circular arc is:

[0024] x 2 +y 2 =163 2

[0025] The curve equation of the elliptical arc is:

[0026] x 2 / 29 2 +y 2 / 4 2 =1.

[0027] In the air preheater with wing streamline tube, the inner wall of the wing-shaped cross section heat exchange tube is provided with a vortex generator; the vortex generator is a spiral protrusion and is uniformly distributed along the axial direction of the wing-shaped cross section heat exchange tube.

[0028] The air preheater has the beneficial effects that, compared with the prior art:

[0029] (1) The wing streamline tube has a larger heat exchange area, significantly reduces flow resistance, reduces equipment dust accumulation, improves heat exchange efficiency and energy saving effect;

[0030] (2) The wing-shaped cross section heat exchange tube adopts a staggered arrangement mode, so that the structure is compact and the fluid can fully flow. The design breaks the flow boundary layer, enhances turbulent heat exchange, reduces the dead area, and improves the space utilization rate;

[0031] (3) The wing-shaped cross section heat exchange tube is specially designed, which minimizes the airflow disturbance in the flue gas flow process and enhances the turbulent heat exchange capacity. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The utility model discloses an air preheater whole schematic diagram.

[0033] Figure 2 It is the first form schematic view of the wing-shaped cross-section heat exchange pipe of the utility model;

[0034] Figure 3 It is the second form schematic view of the wing-shaped cross-section heat exchange pipe of the utility model;

[0035] Figure 4 It is the schematic view of the vortex generator structure of the utility model. DETAILED DESCRIPTION

[0036] The utility model is further described below in combination with examples.

[0037] The utility model provides a kind of air preheater using wing streamline pipe, solve the problem of low heat exchange efficiency, big resistance in prior art.

[0038] Air preheater using wing streamline pipe, as shown in Fig. Figure 1 It specifically includes shell 1, air pipe box 2, air inlet 3, air outlet 4, flue gas inlet 5, flue gas outlet 6, two wing streamline tube bundles 7, two tube plates 8. Wherein, shell 1 is vertically placed rectangular shell structure;Air inlet 3 is arranged at the upper of the front wall of shell 1;Air outlet 4 is arranged at the lower of the front wall of shell 1;Air pipe box 2 is arranged at the rear wall of shell 1;One of tube plate 8 is arranged at air inlet 3;Another tube plate 8 is arranged at air outlet 4;Each tube plate 8 corresponds to install one wing streamline tube bundle 7;Two wing streamline tube bundles 7 are axially horizontally arranged up and down;The inlet end of wing streamline tube bundle 7 located at upper is aligned with air inlet 3, and outlet end is butt-jointed with air pipe box 2;The inlet end of wing streamline tube bundle 7 located at lower is butt-jointed with air pipe box 2, and outlet end is aligned with air outlet 4;Flue gas inlet 5 is arranged at the bottom of shell 1;Flue gas outlet 6 is arranged at the top of shell 1.

[0039] In the utility model, shell 1 is made of carbon steel material;Wing-shaped cross-section heat exchange pipe 71 is made of carbon steel material.

[0040] Air inlet 3, wing streamline tube bundle 7 located at upper, air pipe box 2, wing streamline tube bundle 7 located at lower, air outlet 4 form transverse U-shaped air flow channel;After external cold air enters from air inlet 3, in turn pass through wing streamline tube bundle 7 located at upper, air pipe box 2, wing streamline tube bundle 7 located at lower, flow from air outlet 4.

[0041] The utility model sets up air inlet in the upper portion of shell, and sets up air outlet in the lower portion of shell.Flue gas inlet is arranged at the bottom of shell, and flue gas outlet is arranged at the top of shell.Cold and hot fluid countercurrent arrangement can increase average temperature difference, and enhance heat exchange.

[0042] High-temperature external flue gas enters the casing 1 through the flue gas inlet 5, and exchanges heat with the two wing-shaped streamlined tube bundles 7 inside the casing 1. After heating the cold air flowing inside the wing-shaped streamlined tube bundles 7, the gas is discharged from the flue gas outlet 6.

[0043] The airfoil-shaped tube bundle 7 consists of multiple airfoil-shaped heat exchange tubes 71; the multiple airfoil-shaped heat exchange tubes 71 are arranged in a staggered manner; the staggered distances of the centerline rows and columns of adjacent airfoil-shaped heat exchange tubes 71 are 20mm and 40mm, respectively.

[0044] The tube sheet 8 is a plate-like structure; one tube sheet 8 is installed above the front wall of the shell 1; the other tube sheet 8 is installed below the front wall of the shell 1; the two tube sheets 8 achieve a seal on the front wall of the shell 1; the tube sheet is provided with through holes corresponding to the cross-sectional shape of the airfoil heat exchange tube 71, and the through holes are arranged in a staggered order; multiple airfoil heat exchange tubes 71 corresponding to the airfoil streamline tube bundle 7 extend into the through holes; so that the external cold air flows in the airfoil streamline tube bundle 7 and does not mix with the external high-temperature flue gas.

[0045] like Figure 2 As shown, the cross-sectional shape of the airfoil-shaped heat exchange tube 71 is composed of a half ellipse 711 and two circular arcs 712; the half ellipse 711 is located at the bottom and opens upward; each opening sidewall of the half ellipse 711 is linearly connected to one circular arc 712; the two circular arcs 712 intersect to form a pointed top structure.

[0046] The equation of the curve representing half an ellipse 711 is:

[0047] x 2 / 30 2 +y 2 / 7 2 =1

[0048] The equation of the arc 712 is:

[0049] x 2 +y 2 =163 2 .

[0050] The front end of the pipe has a semi-elliptical cross section, and the rear end forms a pointed tail through two curved arcs to reduce fluid eddies and resistance.

[0051] like Figure 3 As shown, the cross-sectional shape of the airfoil-shaped heat exchange tube 71 is composed of a half ellipse 711, two circular arcs 712, and an elliptical arc 713; the half ellipse 711 is located at the bottom and opens upward; each sidewall of the opening of the half ellipse 711 is linearly connected to one circular arc 712; the elliptical arc 713 opens downward, and each sidewall of the opening of the elliptical arc 713 is linearly connected to the top of one circular arc 712.

[0052] The equation of the curve of the semi-ellipse 711 is:

[0053] x 2 / 30 2 +y 2 / 7 2 =1

[0054] The equation of the arc 712 is:

[0055] x 2 +y 2 =163 2

[0056] The equation of the elliptic arc 713 is:

[0057] x 2 / 29 2 +y 2 / 4 2 =1.

[0058] The front end of the pipe also adopts a semi-elliptical cross section, and the rear end forms an arc-shaped tail through two circular arcs and a small elliptical arc to enhance the stability of fluid flow.

[0059] like Figure 4 As shown, an airfoil-shaped heat exchange tube 71 has an eddy current generator 10 installed on its inner wall; the eddy current generator 10 is a spiral protrusion and is evenly distributed along the axial direction of the airfoil-shaped heat exchange tube 71.

[0060] The manufacturing method of the streamlined tube bundle 7 of the wing is as follows:

[0061] Step 1: Determine the airfoil-shaped heat exchange tube 71 and its manufacturing method based on the design parameters;

[0062] Step 2: Fabricate airfoil-shaped heat exchange tube 71 using an extrusion molding process;

[0063] Step 3: Install an eddy current generator 10 inside the airfoil-shaped heat exchange tube 71;

[0064] Step 4: Assemble several processed airfoil-shaped heat exchange tubes 71 into an airfoil-shaped streamlined tube bundle 7.

[0065] Step 5: Install the wing-shaped streamlined tube bundle 7 into the housing 1.

[0066] The shell 1 is square, and is provided with an air pipe box 2. The shell 1 can be made of carbon steel, and the wall thickness is determined according to the working pressure and temperature. The air pipe box 2 adopts an arc-shaped shell, and is used for connecting air inlets and outlets to make air flow. The air inlet 3 is arranged at the upper part of the shell 1, and is used for inputting low-temperature air to be heated. The air outlet 4 is arranged at the lower part of the shell 1, and is used for outputting high-temperature air after heating. The positions of the air inlet 3 and the air outlet 4 can be adjusted according to actual requirements to achieve optimal flow organization. The flue gas inlet 5 is arranged at the bottom of the shell 1, and is used for inputting high-temperature flue gas discharged by a heating furnace. The flue gas outlet 6 is arranged at the top of the shell 1, and is used for outputting low-temperature flue gas after heat transfer. The positions of the flue gas inlet 5 and the flue gas outlet 6 can also be adjusted according to actual requirements.

[0067] The airfoil streamlined tube bundle 7 is arranged in the shell 1, and is composed of a plurality of airfoil cross-section heat exchange pipes 71. The airfoil cross-section heat exchange pipe includes two types: the first type is a tail pointed pipe composed of a half ellipse and two circular arcs, the curve equation of the half ellipse is x 2 / 30 2 +y 2 / 7 2 = 1, and the curve equation of the two circular arcs is x 2 +y 2 = 163 2 . The front end of the pipe has a half-ellipse cross section, and the rear end has a pointed tail formed by the two curved circular arcs, so as to reduce fluid vortex and resistance; the other type is a tail arc airfoil pipe composed of a half ellipse, two circular arcs and a small ellipse arc, the curve equation of the small ellipse arc is x 2 / 29 2 +y 2 / 4 2 = 1. The front end of the pipe also has a half-ellipse cross section, and the rear end has an arc-shaped tail formed by the two circular arcs and the small ellipse arc, so as to enhance fluid flow stability. The pipe material is carbon steel, and the wall thickness is determined according to actual conditions. The carbon steel has good corrosion resistance and heat conductivity.

[0068] As shown in Figure 1 , the airfoil streamlined tube bundle 7 adopts a staggered arrangement mode, and the staggered distances of the center lines of the rows and columns of adjacent airfoil cross-section heat exchange pipes 71 are 20 mm and 40 mm respectively. The structure can be compact, and the fluid can flow fully. The design breaks the flow boundary layer, enhances turbulent heat exchange, reduces the dead area and improves the space utilization rate.

[0069] As shown in Figure 2 and Figure 3As shown, the air preheater design with tail pointed tube is suitable for boiler system. The structure has very smooth streamline in high speed airflow and good tail coverage, showing the characteristics of low resistance and high heat exchange performance, suitable for equipment with very high flow rate requirement. The air preheater design with tail arc tube is suitable for applications in chemical process which requires stable airflow. The structure is suitable for high efficient heat exchange under lower airflow speed. If there is no particularly high flow rate, the heat exchange effect of the two types is similar, and the arc tail is easier to manufacture, so the low flow rate can use this type.

[0070] As shown in Figs. Figure 2 , 3 , the fluid streamline coverage of the two wing-shaped cross-section heat exchange tubes is much larger than that of the circular tube or the elliptical tube. The wing-shaped cross-section tube can increase the contact area between the heat exchange tube and the fluid, i.e. increase the heat exchange area, and improve the heat exchange rate. On the other hand, the flow of the wing-shaped cross-section tube is more smooth, effectively reducing the pressure drop and reducing the flow resistance effect, improving the heat exchange effect, and not easy to accumulate dust, prolonging the service life.

[0071] The tube plate 8 is arranged on both sides of the shell 1, used for supporting and fixing the wing streamline tube bundle 7. In order to further improve the heat exchange efficiency in the tube, the vortex generator 10, i.e. the spiral groove, is arranged on the inner wall of the wing streamline tube bundle 7. Figure 4 As shown, the vortex generator 10 is a spiral protrusion, uniformly distributed along the axial direction of the pipeline. The vortex generator 10 can enhance the turbulent heat exchange in the tube and improve the heat transfer coefficient.

[0072] The working principle of the utility model is as follows: the low-temperature air to be heated enters the wing streamline tube bundle 7 in the upper part of the air preheater from the air inlet 3, then passes through the air pipe box 2 to reach the wing streamline tube bundle in the lower part, and finally flows out from the air outlet 4. At the same time, the high-temperature flue gas enters the air preheater shell 1 from the bottom flue gas inlet 5, sweeps the wing streamline tube bundle 7 for heat exchange, and finally is discharged from the flue gas outlet 6. Due to the adoption of the wing streamline tube bundle, staggered arrangement and vortex generator and other technologies, the heat exchange efficiency is significantly improved.

[0073] The manufacturing method of the air preheater comprises the following steps: (1) determining the pipe material and manufacturing method according to the design parameters; (2) preparing the wing streamline tube by using extrusion molding process; (3) arranging the vortex generator in the tube; (4) assembling a plurality of treated wing streamline tubes into a tube bundle; (5) installing the tube bundle into the shell to complete the assembly of the air preheater.

[0074] The air preheater has the advantages of compact structure, excellent heat transfer performance, low cost and the like, is suitable for a waste heat recovery system of various industrial boilers and heating furnaces, can significantly improve system thermal efficiency, realizes energy saving and emission reduction, and has wide application prospect.

[0075] The wing streamline tube design has greater heat exchange area, significantly reduces flow resistance, reduces equipment dust accumulation, and improves heat exchange efficiency and energy saving effect.

[0076] The wing streamline tube bundle adopts staggered arrangement, further improves heat exchange efficiency and space utilization, and reduces manufacturing cost.

[0077] The utility model discloses although has disclosed above like this with better implementation example, but it is not used to limit the utility model, any person skilled in the art can utilize the method and technical content disclosed above to make possible change and modification to the utility model technical scheme without departing from the spirit and scope of the utility model, therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the utility model, all belong to the protection scope of the utility model technical scheme.

Claims

1. An air preheater employing a winged streamline tube, characterized by: The shell (1), the air pipe box (2), the air inlet (3), the air outlet (4), the flue gas inlet (5), the flue gas outlet (6), two wing streamline tube bundles (7), and two tube plates (8) are included. The shell (1) is a vertical rectangular shell structure; the air inlet (3) is arranged above the front wall of the shell (1); the air outlet (4) is arranged below the front wall of the shell (1); the air pipe box (2) is arranged on the rear wall of the shell (1); one of the tube plates (8) is arranged at the air inlet (3); the other tube plate (8) is arranged at the air outlet (4); each tube plate (8) is correspondingly provided with one wing streamline tube bundle (7); the two wing streamline tube bundles (7) are arranged in an axial and horizontal manner; the inlet end of the upper wing streamline tube bundle (7) is aligned with the air inlet (3), and the outlet end is connected with the air pipe box (2); the inlet end of the lower wing streamline tube bundle (7) is connected with the air pipe box (2), and the outlet end is aligned with the air outlet (4); the flue gas inlet (5) is arranged at the bottom of the shell (1); the flue gas outlet (6) is arranged at the top of the shell (1).

2. An air preheater employing aerofoil streamline tubes as claimed in claim 1, wherein: The air inlet (3), the upper wing streamline tube bundle (7), the air pipe box (2), the lower wing streamline tube bundle (7), and the air outlet (4) form a transverse U-shaped air flow channel; after the external cold air enters the air inlet (3), the external cold air sequentially passes through the upper wing streamline tube bundle (7), the air pipe box (2), and the lower wing streamline tube bundle (7), and then flows out from the air outlet (4).

3. An air preheater employing aerofoil streamline tubes as claimed in claim 2, wherein: The external high-temperature flue gas enters the shell (1) from the flue gas inlet (5), exchanges heat with the two wing streamline tube bundles (7) in the cavity of the shell (1), heats the cold air flowing in the wing streamline tube bundle (7), and then discharges the heated air from the flue gas outlet (6).

4. An air preheater employing aerofoil streamline tubes as claimed in claim 2, wherein: The wing streamline tube bundle (7) is composed of a plurality of wing-shaped cross-section heat exchange pipes (71); the plurality of wing-shaped cross-section heat exchange pipes (71) are arranged in a staggered arrangement manner; the staggered distances of the center lines of the adjacent wing-shaped cross-section heat exchange pipes (71) are 20 mm and 40 mm, respectively.

5. An air preheater employing aerofoil streamlined tubes as claimed in claim 4, wherein: The tube plate (8) is a plate structure; one of the tube plates (8) is arranged above the front wall of the shell (1); the other tube plate (8) is arranged below the front wall of the shell (1); the two tube plates (8) seal the front wall of the shell (1); the tube plate is provided with through holes corresponding to the cross-sectional shape of the wing-shaped cross-section heat exchange pipe (71), and the through holes are arranged in a staggered manner; the plurality of wing-shaped cross-section heat exchange pipes (71) of the wing streamline tube bundle (7) extend into the through holes; the external cold air flows in the wing streamline tube bundle (7) without mixing with the external high-temperature flue gas.

6. An air preheater employing aerofoil streamlined tubes as claimed in claim 4, wherein: The cross-sectional shape of the wing-shaped cross-section heat exchange pipe (71) is composed of a half-ellipse (711) and two circular arcs (712); the half-ellipse (711) is located at the bottom and has an opening upward; each opening side wall of the half-ellipse (711) is linearly connected with one circular arc (712); the two circular arcs (712) intersect to form a top pointed structure.

7. An air preheater employing aerofoil streamlined tubes as claimed in claim 6, wherein: The curve equation of the half-ellipse (711) is: x 2 / 30 2 +y 2 / 7 2 =1 The curve equation of the circular arc (712) is: x 2 +y 2 = 163 2 .

8. An air preheater employing aerofoil streamlined tubes as claimed in claim 4, wherein: The cross section shape of the airfoil cross section heat exchange pipe (71) is composed of a half ellipse (711), two circular arcs (712) and an elliptical arc (713); the half ellipse (711) is located at the bottom and opens upward; each opening sidewall of the half ellipse (711) is linearly connected with one circular arc (712); the elliptical arc (713) opens downward, and each opening sidewall of the elliptical arc (713) is linearly connected with the top of one circular arc (712).

9. An air preheater employing aerofoil streamlined tubes as claimed in claim 8, wherein: The curve equation of the half ellipse (711) is: x 2 / 30 2 +y 2 / 7 2 =1 The curve equation of the circular arc (712) is: x 2 +y 2 = 163 2 The curve equation of the elliptical arc (713) is: x 2 / 29 2 +y 2 / 4 2 =1.

10. An air preheater employing aerofoil streamlined tubes as claimed in claim 4, wherein: The inner wall of the airfoil cross section heat exchange pipe (71) is provided with a vortex generator (10); the vortex generator (10) is a spiral protrusion and is uniformly distributed along the axial direction of the airfoil cross section heat exchange pipe (71).

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