JPS6091196A - Air preheater - Google Patents

Abstract

PURPOSE:To remarkably reduce the size of an air preheater by forming the sectional shape of a heat transfer tube in a flat state, bringing the long diameter direction of the flat section in coincidence with the passing direction of the outer fluid of the tube, thereby mounting many tubes in the same area without decreasing the capacity. CONSTITUTION:The long diameter of a flat heat transfer tube 7 coincides with the direction of an arrow C passing the outer fluid of the tube. The shape of the tube 7 is, for example, in a flat shape by pressing the circular steel pipe having 45mm. of diameter so that the short diameter (g) is 14mm., the long diameter (f) is 62.65mm., and the peripheral length is 141.3mm.. The number of the tubes is 14 rows per one tube group and 28 rows of two groups, 38 rows of the direction perpendicular to the 28 rows, totally to 1,064. The size of the gap between the tubes 7 is 20mm. in the long diameter direction, and 15mm. in the short diameter direction (n). The total value of the size (n) is 15mm.X39=585mm., thereby maintaining the exhaust gas side pressure loss to the prescribed value or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a convection type multitubular air preheater for exhaust heat recovery of industrial combustion equipment.

The air preheater mentioned here complies with Japanese Industrial Standard JISB841.
This refers to an air preheater that falls within the scope of the ``1r Air Preheater Performance Test Method.'' The gas heated by this device is combustion air, but it is not suitable for industrial combustion equipment that uses gaseous fuel. This device may also heat the fuel gas.

There are two types of air preheaters: a convection type, a radiation type, and a combined convection type, and two types of convection types: a multi-tube type and a fin-tube type. The fin tube type has a large number of cast fin tubes arranged perpendicular to the flow of extratubular fluid. A finned tube is a cast tube having an oval cross section and a large number of fins formed inside and outside the tube, as seen in, for example, Japanese Patent Publication No. 40-24424 and Japanese Patent Publication No. 43-5349. The fin-tube type has low production efficiency because it uses a special cast tube, and because the cross-sectional size of the cast tube must be increased to a certain extent, there is a limit to its heat transfer efficiency. The multi-tube type was created to solve the problems of the fin-tube type, and as shown in Figure 1, a large number of circular steel pipes are arranged perpendicular to the flow of extra-tubular fluid. Common.

However, in recent years, compact air preheating 2 with 11G performance has been added.
Demand for g is increasing. The present invention meets this need,
In a convection type multi-tube air preheater, the purpose is to create an air preheater that occupies less space at the same capacity compared to that using a conventional circular steel vibrator.

In order to achieve this object, in the present invention, a heat exchanger tube with a flat cross-sectional shape is used instead of the conventionally used circular steel pipe, and the flat 11'jr surface is The major axis direction and the passage direction of the fluid outside 1a are made to match,
The air preheater is configured by appropriately arranging heat transfer tubes corresponding to the usage conditions of the air preheater.

In the fin-tube type, the cross-sectional shape of the first tube is made flat, and the long axis direction of the flat cross section is made to coincide with the passage direction of the extratubular fluid. However, this requires a large diameter. The purpose of this invention is to improve the heat transfer efficiency of cast tubes, which are completely different from the technical idea of the present invention described later, and the structure and effects of the present invention in multi-tube systems have not been recognized at all. .

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

Figures 1 to 3 show a conventional convection type air preheater 2, which is a comparative example, and Figures 1 to 0 show a conventional convection type air preheater 2. Air preheating 2: ζG, which is the first embodiment of "I", is shown. In Figure 1, flow through flue 1.
The exhaust gas moves in the direction of arrow A. The circular steel pipes 3 forming the heat transfer surface of the air preheater 2 installed in the flue 1 form four groups of pipes and are installed perpendicular to the exhaust gas. Air moves through it in the direction of arrow B.

FIG. 3 is a schematic cross-sectional view showing an enlarged part of the section taken along the line XX in FIG. 1, and shows how the circular steel pipe 3 is arranged.

The slit plate 4 is a member made of small flat steel and has a cross-shaped cross section.
It is inserted over almost the entire length of the The outer diameter a of the circular steel pipe 3, which is a heat transfer tube, is 451Xm, and the peripheral length is 141Xm.
．． This is my third opinion. The number of heat transfer tubes is 14 rows per -1 tube group in the exhaust gas passing direction (direction of arrow entry), 56 rows in 4 tube groups, and 19 rows in the direction perpendicular to this, so the total number is I, (J6
There are 4 pieces. The mutual gap dimension (gap dimension with the alignment (-1 peripheral edge) b) of the circular steel pipes 3 is 20M.This dimension is determined in part by the value of the gas side pressure loss by ensuring the passage solidification of the exhaust gas. is determined so that it is below a certain value.The planar dimensions of the tube group are the length per tube group in the exhaust gas passage direction C' = (45iz x 14 tubes) +
(2C1#X] - 5 points) = 930 continuations, length of brass group 4
- (4,57g1X 19 pieces) 10 (20MX20 places) =], 255m. The length e of the heat exchanger tube is 2,7
00wtr. The total value of the outer surface dryness of the heat exchanger tube 3 is:
0.1413 m x 2.7 m x 1,064 x
""405.927', and the total volume of the arrival and group is 3
．． 72 mX 1.255 mX 2.7 In, =
It is 1205m3.

In FIG. 4, the exhaust gas flowing through the flue 5 moves in the direction of arrow C. Flat heat exchanger tubes 7 form the heat transfer surface of the air preheater 6 installed in the flue 5. The pipes form two sets of pipes and are installed perpendicular to the exhaust gas. Inside it,
Air moves in the direction of the arrow.

FIG. 6 is an enlarged view of a portion of the Y-Y cross section in FIG. 4, and shows the shape and arrangement of the flat heat exchanger tubes 7. The long diameter direction of the flat heat exchanger tube 7 coincides with the passage direction of the extratubular fluid, that is, the direction of arrow C. 11. The shape of the flat heat exchanger tube 7 was made by pressing the circular steel pipe with a diameter of 45 mm in the comparative example to make it flat, and the short axis g was 14M. The shape is the same as that shown in II, and the major axis is 62.65 ytm, and the circumference is 1413 ytm, which is the same as the circumference of the comparative example.

The number of heat transfer tubes is 1 in the exhaust gas passage direction (arrow C direction).
There are 14 rows per tube group, 28 rows in two tube groups, and 38 rows in the direction perpendicular to this, for a total number of 1,064 tubes. The mutual clearance between the flat heat exchanger tubes 7 (the clearance between the flat heat exchanger tubes 7 and the peripheral edge) is such that the long diameter direction clearance m is 20H)1. The width n in the minor axis direction is 15'M. The total value of this minor diameter direction clearance dimension 1], 15MX 39 locations = 585 m, is:
This dimension is necessary to keep the pressure loss on the exhaust gas side below a certain value when the exhaust gas passes through the air preheater 6. The gap size in the comparative example is 20 prints, but the total value is 2 o ytm x 20 places = 100 layers, which is wider in the 585th layer of the first example. The planar dimensions of the tube group are: length p2 (6265 mm x 14 pieces) + (20ygz x 1) per tube group in the exhaust gas passage direction (arrow C direction)
5 locations) = 1,177.1 ytm, length of brass group 2 x I) = 2,354. ．． 2, the length q in the direction perpendicular to this is = (liX38 lines) + (15#X39 locations) = 1.117#I. The length C of the heat exchanger tube 7 is 2.700M, which is the same as the length of the vibrator 3 made by Circular Shape in the comparative example. Total i of the outer surface area of the heat exchanger tube 7
The t-value is 0.1413 m x 2.7 m x L0
64 pipes = 405.92-W, the total volume of the tube group is 2.
3542 m Xl, 117 m x 2.7 m = 7. '
This is JOOm3.

In order to compare and contrast the comparative example and the first embodiment of the present invention, the usage conditions and specifications are summarized in Table 1 and Table 2, respectively, and are shown below.

Table 1 Months of use of air preheater] The basic values given as conditions are shown in Table 1: (a) exhaust gas inlet temperature, (b) exhaust gas flow rate, and (c) Exhaust gas side pressure 4
(d) Air inlet temperature, (e) Air outlet IZJ 'lrA degree, (f) Air flow rate, (g) Air side pressure loss (upper limit). be.

If these seven types of numerical values are different for the two air preheaters with different configurations, it can be said that the two air preheaters have basically the same ability. If we compare the usage conditions of the comparative example and the first example in Table 1, we can see that (c) exhaust gas side pressure loss, (e) air outlet temperature,
(g) Although the first embodiment is slightly superior in terms of pressure loss on the air side, it can be said that both have almost the same ability. Next, Table 2 compares the specifications of both. Although the total number, length, and outward surface area of the heat exchanger tubes are all equal, the planar dimensions and volume of the group are i
Example f has a smaller value, and if the volume ratio is taken as 100% for the comparative example, Example 56.
It's just the third section. In other words, the air preheater of the first embodiment has a capacity of approximately
Achieved 0% miniaturization. This is because the cross-sectional shape of the heat transfer envelope is flat, and the long axis direction of the flat cross section matches the passage direction of the extratubular fluid. A large number of heat transfer tubes can be placed in the tube, and the number of gaps between the tubes also increases.
This is because the gap size in the short diameter direction can also be reduced without increasing the exhaust gas side pressure loss.

Furthermore, when conditions such as the velocity of the fluid outside the tube and the velocity of the fluid inside the tube are the same, a flat heat transfer tube has a higher heat transfer coefficient than a circular pipe, so it is more advantageous.

In addition to the flat cross-sectional shape of the heat transfer j'H shown in FIG. 6, there are also examples of the flat cross-sectional shape of the heat transfer j'H in "Main 1"; These include those with alternating heat transfer fins 9 on the inner surface, as shown in FIG. 9, and those with wavy inner and outer surfaces as shown in FIG. The shapes shown in Figures 7 to 9 are compared with those shown in Figure 6, and when the major axis and minor axis are the same, as the heat transfer area increases, the heat transfer coefficient also increases at the same point, so the object of the present invention is further reduced. easily achieved.

In the case of steel, flat heat exchanger tubes can be manufactured using conventional hot extrusion manufacturing equipment. Further, the products shown in FIGS. 6 and 9 can be manufactured by using conventional electric resistance welding pipe equipment J and forming the pipes as shown in the figures in the forming process. Materials that can be cold worked can also be produced from circular tubes by cold working. If it is made of ceramic, it can be molded freely.

10 and 11 show a convection type multi-tube air preheater 11 according to a second embodiment of the present invention. The cross-sectional shape of the heat transfer tube 12 is flat, and the long axis direction of the flat cross section is made to coincide with the passage direction of the extra-tube fluid (exhaust gas) (indicated by an arrow in the flue 10).Heat Transfer 9312 As shown in FIG. 10, it has a U-shape in a side view, and the air moves in the direction of arrow F.The second embodiment has a simpler bay h1 construction than the first embodiment, and Less affected by thermal expansion of heat exchanger tubes.

12 and 13 show a convection type multi-tube air preheater 14 according to a third embodiment of the present invention. The cross-sectional shape of the heat exchanger tube 15 is flat, and the longer diameter direction of the flat shape W11fu is made to coincide with the passage direction of extratubular fluid (exhaust gas) (indicated by arrow G in the flue 13). The heat exchanger tube 15 is the first
As shown in Fig. 3, it has a U-shape in front view, and air moves in the direction of arrow ①. The third embodiment is based on the first
Compared to the example, the structure is only P31, and.

The effect of thermal expansion of the heat exchanger tube is small, and it is easier to bend the porcelain heat exchanger tube into a slotted shape compared to the 9↓2 embodiment.

14 and 15 show a convection multi-tube air preheater 17 according to a fourth embodiment of the present invention. The cross-sectional shape of the heat exchanger tube 18 is flat, and the longitudinal direction of the flat cross section and the extra-tubular fluid (
In the fourth embodiment, the exhaust gas flowing through the flue 16 moves in the direction of the arrow (■) and flows inside the heat exchanger tube 8. Air, which is an extratubular fluid, moves in the direction of arrow J and is guided by baffle board J9, causing flat heat transfer 1'-';
' It moves at right angles to 18 and in the major axis direction of the flat cross section. The fourth embodiment can also be used when there is a lot of dust in the exhaust gas.

In addition, each embodiment can also be used with the air flow direction reversed.

In the present invention, the transverse 1fii shape of the heat transfer tube is made into a flat shape, and by making the long axis direction of the flat cross section coincide with the passage direction of the fluid outside the tube, there is no reduction in performance compared to ILF products. By arranging a larger number of heat exchanger tubes with the same outer circumference in the same area, a significant reduction in size can be realized, and by installing the product of the present invention in the flue, the flue space can be significantly omitted. , equipment costs and space can be reduced. The industrial contribution of the present invention is significant.

[Brief explanation of drawings]

Fig. 1 is a schematic side view showing how a conventional multi-tubular air preheater is used as a comparative example, Fig. 2 is a schematic front view of the same, and Fig. 3 shows a part of the X 7 FIG. 4 is a schematic side view showing how the air preheater of the first embodiment is used, FIG. 5 is a schematic top view, and FIG. A schematic cross-sectional view showing an enlarged view of −g1≦ of the cut plane, FIGS. 7 to 9 are cross-sectional views showing the cross-sectional shape of the heat exchanger tube, and FIG. 10 is a schematic view showing how the air preheater of the second embodiment is used. 11 is a schematic top view, FIG. 12 is a schematic side view showing how the air preheater of the third embodiment is used, FIG. 13 is a schematic front view, and FIG. 14 is a schematic diagram of the fourth embodiment. FIG. 15 is a side view of A-road showing the usage state of an example air preheater, and FIG. 15 is a schematic plan view. ■, 5, l0113.16...flue, 2.6-11.
14.17...Air preheater, 3.7= 12.15.
18... Heat exchanger tube patent applicant Makoto Kobe, patent attorney representing Yonago Shoko Co., Ltd. Figure 5 Dan Figure 9 Procedural amendment document March 23, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1, case Display of 1983 Patent Application No. 198347 2 Title of the invention Air preheater 3 Relationship with the case of the person making the amendment Patent applicant 4, agent 6 Number of inventions increased by the amendment 0 7, Subject of the amendment 41&.I of the detailed description of the invention in the specification and drawing 8,
Contents of amendment (1) Specification 9' U3 Tei No. 17 fj 11 "and"
is corrected to "and". (2) Specification, page 6, #9 #"JIkl "62.65 ya, circumference" is corrected to 1-62.65 ya, periphery". (3) Specification page 8, line 5 1-1 “Exhaust gas side pressure loss (paHg)
J (2 strokes n pressure. (4) Specification 8th negative - 91st) 11F air side pressure loss (uni Hg) J is ``air side pressure loss (/MRH
,,o) Correct the object to J. (5) On page 8 of the specification, 5th heat tube 11 "heat exchanger tube 8" is corrected to "heat exchanger tube 18". (6) Revise Figure 1 as shown in the attached sheet. (7) Revise Figure 4 as shown in the attached sheet. (8) Extract Figure 14 as shown in the attached sheet. (9) Correct the information in Figure 15 on a separate sheet. Susunza 1 μ] Tsune

Claims (1)

[Claims] In a convection multitubular air preheater for exhaust heat recovery of industrial combustion equipment, the cross-sectional shape of the heat transfer tube is flat, and the major axis direction of the flat cross section is made to coincide with the passage direction of the fluid outside the tube. air preheater