High flux tube and heat exchanger
High flux tube is a new product combining sintered method and machining technology. They can improve heat transfer coefficient of the inside and outside tubes , thus they can significantly improve overall heat transfer coefficient of tubes. They solve the current problem that heat transfer coefficient increased only on one side of heat transfer enhancement, while the total heat transfer efficiency is still low. They greatly improve the efficiency of the heat transfer tubes and heat exchangers.
Sintered high flux tube is a highly efficient heat exchange tube with a specific structure on the surface of ordinary heat exchange tube, which is sintered by powder metallurgy method. The concave hole of the surface porous layer is communicated with each other, and the boiling heat transfer can be enhanced obviously, and the heat transfer effect can be increased by more than 20 times. This is so far for heat transfer coefficient of the highest pipe type heat transfer element, especially applicable to alkanes, alkenes, alcohols, such as Freon medium.
Compared with the bare tube, the sintered surface porous tube has the following advantages:
(1) it can significantly enhance the boiling heat, reduce the heat transfer area of about half, and have broad application prospects in the chemical and petrochemical plants such as large ethylene and large aromatics.
(2) in a very small difference in the maintenance of boiling, low taste energy recovery and low temperature boiling heat transfer has a great value, can be used to reduce the temperature of the heating steam.
(3) the critical heat load is more than 50% higher than that of the ordinary pipe.
(4) has good scale inhibition performance.
On the one hand, High flux tube can reduce the steam demand. On the other hand, it can improve the heat transfer capability. In a large heat transfer system, because of the need of small temperature differences, the number of reboilers needed is very large. The use of High flux tube can reduce 3/4 the amount of reboilers, and temperature difference ΔT needed for only 5 ℃. Using High flux tube to replace traditional bare tube we can eliminate heat transfer bottlenecks, meet the need of larger heat transfer load, and significantly increase production. At the same time, while keeping machine efficiency, it can reduce cost by using lower steam pressure.
The case-hardened products are as follows:
Sintered porous coating for the outer surface/low fins for the inner surface, Cannelure for the outer surface/ sintered porous coating for the inner surface, Sawtooth surface for the outer surface/ sintered porous coating for the inner surface, fins for the outer surface/ sintered porous coating for the inner surface.
1.1 Material and size of High flux tube
Material: carbon steel, Aluminum, and so on.
Size: external diameter 15～40mm，length 500～12000 mm
Under normal condition, the middle of High flux tube is strengthened section. Plane ends are smooth, so it is easy to wear and to be expanded. High flux tube can do OEM as customers’ need. Products are packed with wooden boxes.
1.2 Applicable medium of high flux heat exchangers
Ethylene glycol, diethylene glycol, ethylene trichloride, ethane, propylene, ethyl alcohol.
1.3 Applications of high flux heat exchangers
High flux heat exchanger can be used in phase change equipment, such as, carburetor, evaporator, condenser and reboiler, etc. To be specific, such as ethylene carburetor, the overhead condenser and reboiler of ethylene separation device , combination plant of ethylene glycol evaporation and aromatic, main condenser-evaporator of air separation unit. As well as the natural gas liquefaction, cryogenic refrigeration, air separation, and sea water desalination, etc.
（1）Oil refining and petrochemical installations
Such as overhead condenser and reboiler of ethylene separation device, ethylene carburetor, catalytic slurry oil evaporator, ethanol evaporator and ethylene glycol evaporator, etc. It can reduce more than 80% heat transfer area, and can also lower refrigerator horsepower. In the long-term operation process, porous surface with enhanced boiling heat transfer is very stable, and no coking or scaling phenomenon has occurred. At the same time it can greatly reduce heat medium consumption, so far as to lower the heat medium temperature.
（2）Natural gas purification and separation devices
For example, in the reboiler condensers of cryogenic air separation plant. On the one hand, it can reduce initial cost of evaporation - condensing (cooling) heat exchanger (cut down heat transfer surface); On the other hand, because of the small work temperature difference, it can reduce the power consumption.
(3) Sea water desalination and waste heat utilization
1.4 Analysis of high flux heat exchanger economy
To build a set of megaton ethylene equipment, the total investment is above 20 billion RMB commonly, according to history data, heat exchangers cost accounting for about 30% of the total investment , the cost of heat exchangers in each large ethylene project will reach neally 7 billion RMB. But since Chinas energy use efficiency is only 34%, equivalent to that of developed countries 20 years ago, ten percent lower than them now. Developing a higher efficient heat exchanger in smaller temperature difference and less heat transfer surface can be the first step directly related to industrial energy saving development. Using High flux tube and high-efficiency heat exchangers are the most efficient, and also the most economical means to improve the use efficiency of energy.
At present the demand of High flux tube in China is increasing rapidly, in the ethylene industry and other fields, High flux tube and high-efficiency heat exchangers have broad application prospects, thus it has huge potential market demand. There are a lot of high efficient heat transfer tubes in the United States, Japan and Germany, but the technology is still a secret to China, so domestic ethylene industry was forced to use imported High flux tubes.
High flux tubes developed by our company can reduce heat transfer surface and the size (about 80%) of traditional heat exchangers, also can reduce the amount of heat exchangers in large projects and cut down the piping, control foundation construction and plane landed cost. By replacing tube bundle of heat exchangers in existing plant, the original head, shell, piping etc. can be used again.
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