Composite material teflon heat exchanger and preparation method thereof

Abstract

The invention discloses a composite material teflon heat exchanger and a preparation method thereof. The heat exchanger comprises a heat exchange tube bundle, the heat exchange tube bundle comprises a plurality of heat exchange tubes and a tube plate, the two ends of each heat exchange tube are arranged on the tube plate, each heat exchange tube comprises a metal tube, and a tetrafluoroethylene heat shrink tube is arranged on each metal tube. The characteristics that the metal tubes are good in mechanical strength and high in heat exchange efficiency and the polytetrafluoroethylene material is low in surface energy and not prone to dirt sticking are utilized, the polytetrafluoroethylene heat shrink tubes which are very easy to purchase sleeve the metal tubes, and the composite heat exchange tube is formed through combination. The heat shrink tubes and the polytetrafluoroethylene tubes have the same function, but the thickness of the heat shrink tubes is only 1 / 5-1 / 20 of that of the polytetrafluoroethylene tubes, so that the heat conduction efficiency is improved by 5 times or above compared with that of a polytetrafluoroethylene tube heat exchanger made of a single material, and as the metal tubes are used as supports of the heat shrink tubes, the mechanical strength of the composite material teflon heat exchanger is basically the same as that of a common shell-and-tube heat exchanger, the composite material teflon heat exchanger can be applied to a high-pressure technological process, and the application field is wide.

Description

technical field [0001] The invention relates to a heat exchanger, in particular to a composite polytetrafluoroethylene heat exchanger with automatic cleaning function. Background technique [0002] Heat exchangers are important equipment for heat exchange and transfer in the production process of industrial processes. They have corrosion problems in many environments and fouling of heat exchange surfaces in almost all application fields. Corrosion of heat exchangers The heat exchanger shortens the service time and increases the equipment investment cost of the enterprise; the fouling of the heat exchanger will reduce the heat exchange efficiency and increase energy consumption, increase the operating cost of the enterprise, and cause production accidents in severe cases. [0003] In a severely corrosive environment, almost all heat exchange equipment made of metal materials cannot operate stably for a long time; therefore, heat exchangers made of non-metal materials such as ...

AI Technical Summary

Problems solved by technology

Although the heat exchanger made of polytetrafluoroethylene tube has the advantages of strong corrosion resistance, not easy to scale, wide working temperature range, light weight and long service life, it also has poor mechanical strength, poor thermal conductivity and poor processing performance. Disadvantages and deficiencies such as poor and poor surface adhesion:

[0007] First, poor mechanical strength

[0008] Compared with metal tubes, polytetrafluoroethylene heat exchange tubes have much poorer mechanical properties, and cold flow creep can occur at lower temperatures and small stresses; their use temperature range and pressure resistance are greatly limited. It is also necessary to prevent mechanical damage

[0009] Second, poor thermal conductivity

[0012] Due to the use of small-diameter thin PTFE heat exchange tubes, it is found that the purity of the medium passing into the tube-side medium channel is high during use, and large medium particles must be prevented from entering the tube, otherwise it will be easily blocked and affect the heat exchange efficiency; When the tube-side medium is heated, the medium is easy to vaporize, resulting in air resistance in the PTFE tube, hindering the flow of the medium and affecting the heat transfer efficiency

[0013] If the heat exchanger is made of large-diameter polytetrafluoroethylene tubes, the wall thickness will be at least 1-3mm, the thermal resistance will be too large, and the heat transfer efficiency will be too low

[0014] Third, the connection between the tube sheet and the heat exchange tube is poor

PTFE tubes are relatively soft and cannot be automatically welded or expanded like metal heat exchangers

Basically, special bonding technology is used. Since PTFE is the plastic with the lowest surface energy and the most difficult to bond among polymers, special treatment must be carried out. At present, the tube-sheet connection technology of PTFE heat exchangers is difficult to operate. Mastery, the production process is not up to mechanization and automation

The principle of tube-sheet bonding process of PTFE is different from that of steel heat exchanger tube-sheet welding. In addition to its material limitation, it cannot be carried out at present. The internal bonding quality inspection can only be carried out through macroscopic inspection methods such as water. Pressure test and air tightness test are used to determine the firmness of the glued surface. Individual defects on the glued surface cannot be measured immediately, and can only be checked and remedied regularly after a period of use.

[0016] Fourth, it is not easy to install online mechanical descaling equipment

However, polytetrafluoroethylene coating heat exchangers require multiple coatings and multiple high-temperature sinterings, requiring more special large-scale equipment, complex processes, high process requirements, high energy consumption, and high cost, so it is not easy to industrialize Production

In addition, the polytetrafluoroethylene coating is to attach the difficult-to-bond material to the metal wall surface with a coupling agent. Due to the chemical stability of the polytetrafluoroethylene material, only the coating occurs during the high-temperature sintering process. The physical changes inside the layer, without the interpenetration effect between the PTFE coating and the metal surface, that is, the combination between the PTFE coating and the metal surface is only a mechanical combination, which means that after the paint particles are sprayed, Attached to the concave and convex points on the surface of the substrate, its combination is related to the surface roughness of the substrate and the anchor structure, and is a mechanical force formed by the interlocking effect of the particles; so this combination is relatively fragile and prone to cracks and brittle cracks And fall off and other problems, such problems often appear in practical applications

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