Finned Tube----Inner finned tube heat exchanger
1 Introduction
Tube heat exchanger widely used in petroleum, chemical, metallurgy , electric power industry , which has a simple structure , easy to manufacture , extensive material , adaptability and other characteristics, is a major industrial production of heat transfer equipment . Currently, a wide range of applications metal tube heat exchanger to heat transfer through the partition , the heat transfer is limited by its size and the heat transfer capability of the partition , which is not high overall heat transfer coefficient ,
Pneumatic stretch tubular heat exchanger is only about 15 ~ ZOW/m20C, tube -type plug-in heat exchanger is about 30 ~ 3w/m2OC. Due to the existence of a comprehensive and tube heat exchanger heat transfer coefficient is low , large equipment, etc. insufficient , for a variety of plug-ins came into heat , finned tube heat exchangers and other new heat exchanger . currently , the development of new and efficient heat exchanger has become the development trend
Potential . Within finned -tube heat exchanger is our latest developed a new type of heat exchanger, domestic initiative , part of a new generation of high efficiency heat exchanger , at present, has been used in industry , and achieved good results.
2 inner finned tube heat exchanger and its application
Within 2.1 finned tube heat exchanger
The main features of the new inner finned -tube heat exchanger is:
By extending the surface heat transfer tubes , enhanced tube heat exchanger ways to improve performance . Inner finned tube with longitudinal ribs straight pipe than the wings of up to 4 to 6 , compared with the normal smooth tube, the tube heat transfer coefficient can be increased 3-4 times. using the finned tube fins
Welding process of welding , the weld the rate of i00. Within finned -tube heat exchanger tube heat exchanger with the general structure is not on differences, the main difference between them lies in the different tubes . Within finned tubes As shown in Figure 1 .
The finned tube specifications are shown in Table 1
Figure 1 in the finned tube
Within the specifications of a finned tube
Do (ram) lh (mm) 8 (ram) crystalline L (ram)
38-89l12-131 ~ 2l22 {4 - 610000
Of which : Do a Governor diameter fin height h a a fin thickness
n a loose fin and a wing of the battalion commander imaginary than 46 L a fin
Compared with the general tube heat exchangers , finned tube within the transducer
Heat has the following advantages:
Compared to the thermal coefficient of ( 1 ) tube . Stretch for the average gas heat exchanger tubes , the tube is often controlled thermal resistance thermal resistance , therefore , essential to improve the heat transfer coefficient of the inner tube . Using finned tubes , the wing of the tube than up to 4 to 6 , heat transfer coefficient can be increased 3-4 times the tube, thereby significantly strengthening the inner tube heat .
( 2 ) heat transfer ability. Transfer coefficient is generally tubular heat exchanger is approximately K-a.a2 /
( 3 ) wall temperature is low. Tubular heat exchanger wall temperature Tb one (a2tz/al ten t) / (a2/al +1), obviously , with the inner tube to a substantial increase in heat transfer coefficient , Tb is drop , when working at high temperature heat exchanger is very important to prolong the life of the heat exchanger (tt, t- tube , respectively , the temperature of the fluid within the tube ) .
( 4 ) compact heat exchanger structure due to exponentially increase the heat transfer coefficient K value , making the heat transfer area greatly reduced the volume of the heat exchanger has been greatly reduced.
2.2 the finned tube heat exchanger applications
We end units Shougang waste heat utilization project in the steam superheater pioneered the use of the finned tube heat exchanger , shown in Figure 2 .
2 Schematic of steam superheater
A hot steam out of a garbage rn} 2 - Camp 3 a case by heat ; 4 a saturated steam
^ rn} 5 a thick plate ; 6 a cupboard full board
Its inner tube finned tube specifications , shown in Figure 3 outer wings
Sheet Table 2, Table 3 .
Figure 3 finned tube specifications
Table 2 finned tube
Table 3 finned tube
Dl (mm) lB (mm) lZ ~ (mm)
Of which : Do an outside diameter Dl an internal diameter Df an outer diameter of the outer fins
h a fin height 8 a n a fin fin thickness within a number of the wing than p0 an outer wings of an outer fin thickness ratio △
Steam superheater measured operating parameters in Table 4
Steam bellows smoke
Population / outlet temperature (℃) 135/157188/15z
Heat load 'kw) ~ 65
Press the hot area (r Ⅱ) 16.7
Comprehensive sets of heat transfer coefficient (w / mk) ~ 16547
Steam superheater measured operating parameters are shown in Table 4. Their process shown in Figure 4 .
Figure 4 Flow Chart
A high temperature bellows ; 2 superheater ; 3 4 compared flue pump ; 5 a precipitator ; 6 anger gas heat exchanger, 7 Drum
Practice shows that the fin -tube steam superheater with high overall heat transfer coefficient , which fully demonstrates its superior enhanced heat transfer performance. Obtained good results in production.
Prospects within 2.3 finned tube heat exchanger
Because of the finned tube is in June 2000 we have just developed a new type of heat exchanger, its scope of application as well as a lot of limitations can be expected within a finned tube heat exchanger will in metallurgy , electric power, petroleum , chemical and other industries have wide spatial development . following metallurgical furnace only an example of the air preheater . use of heat recovery furnace flue gas waste heat in industrial furnace to preheat air or gas can improve the theoretical combustion temperature , improve thermal efficiency , saving energy, generating significant economic benefits , therefore , air preheater has become an important part of the industrial furnace is widely used . traditional air preheater mostly tubular heat exchanger or
Plug-in heat exchanger, there are air temperature is low, the wall temperature is high, the huge structure, especially at high temperatures , short life and other defects , for example , when the flue gas temperature of 800 ℃ , the standard flow rate , heat exchanger the volume under the same conditions , the tubular heat exchanger in general preheated air temperature ~ 320 ℃. wall temperature ~ 570 ℃, and the inner fin-tube heat exchanger to preheat the air may be ~ 500 ℃, the wall temperature to 420 ℃, the visible advantages of finned -tube heat exchanger is very clear . within the finned tube material can be carbon steel or stainless steel in its tube surface can also set various extensions , such as ring rib , rib straight needle rib , etc. to meet the needs of a variety of different conditions , so as to further improve the performance of the heat exchanger .
3 Conclusion
The inner finned tube heat exchanger is a new type of higher education , a domestic initiative , compared with the general tube heat exchangers , heat transfer coefficient with mechanized units , wall temperature is low , compact , long life and other characteristics, in metallurgy , electric power , petroleum, chemical industry, with a wide range of applications.