High-efficiency plate heat exchangers in the petrochemical industry (Part 2)
Release time:
2020-07-26 12:00
Source:
Spiral baffle heat exchanger and ordinaryplate heat exchangerThe difference is that the baffles in the shell side are arranged in a spiral shape, so that the shell-side medium is propelled in a spiral and continuous rotation from the inlet to the outlet, changing the traditional transverse baffle flow method into a longitudinal spiral baffle flow method. The baffle channel is spiral, and there will be no flow "dead zone". Because the medium in the shell side of the heat exchanger is in a spiral plunger flow mode, a velocity gradient is generated in the radial direction of the shell cross-section, placing each heat transfer tube in the vortex of the heat transfer medium, increasing the radial turbulence of the fluid, which is conducive to flushing particles and sediments in the shell side, and preventing fouling deposition.
Generally, heat pipe heat exchangers are widely used in the harsh operating conditions of waste heat recovery in the petrochemical industry, mainly including the production of high-sulfur fuels and other harsh operating conditions. In the production process of the petrochemical industry, high-temperature heating and cracking facilities are very critical facilities. Specifically, in the production of small-molecule olefins, the high-temperature petroleum brain cracking furnace selected has an exhaust gas temperature of 200℃～400℃. Moreover, harsh operating conditions are not conducive to the exhaust of tail gas formed by industrial production. The air preheating heat pipe heat exchanger can use the residual heat of waste gas to heat the air, thus playing a role in combustion. On the one hand, it can save energy and reduce consumption, and on the other hand, it is also conducive to recovering tail gas and avoiding the deterioration of air pollution problems. Nowadays, various combinations of tubular heat exchangers have been widely promoted at home and abroad, so as to achieve good energy saving and drainage effects.
A heat pipe is a heat transfer element with extremely high thermal conductivity. It transfers heat through the evaporation and condensation of working fluid in a fully enclosed vacuum tube. It has extremely high thermal conductivity, good isothermality, arbitrarily changeable heat transfer area on both cold and hot sides, long-distance heat transfer, and controllable temperature, and a series of advantages. Heat exchangers composed of heat pipes have advantages such as high heat transfer efficiency, compact structure, and small fluid resistance loss. Due to its special heat transfer characteristics, the tube wall temperature can be controlled to avoid dew point corrosion. It has been widely used in metallurgy, chemical industry, petroleum refining, boilers, ceramics, transportation, light textile, machinery and other industries to recover heat and comprehensively utilize thermal energy in the process, and has achieved significant economic benefits. There are mainly three types:
Gas-gas heat pipe heat exchangerIt is a new type of heat exchanger that absorbs waste heat from the discharged hot gas and then transfers the heat to the cold air, similar to the air preheater commonly used in boilers. Like economizers and superheaters, air preheaters have become an integral and necessary part of large boilers. Air preheaters accelerate the fuel drying process, reduce the difficulty of ignition of low-grade and wet fuels, expand the economic combustion of these fuels, and can also improve the overall steam production of the boiler.
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