Application of wide-channel plate heat exchanger in alumina production

Application of wide-channel plate heat exchanger in alumina production

Wide-channel plate heat exchanger not only has the advantages of high heat transfer efficiency and compact structure of ordinary plate heat exchanger, but also has the characteristics of deep ripple. So it is especially suitable for the heat transfer between materials with fiber viscosity or solid particles.

The wide-channel plate heat exchanger is a product specially developed for various solid, crystal, fiber, slurry and high-viscosity medium heat exchange conditions. Due to the special design of the heat exchange plate, it ensures that the wide-gap channel is smooth, the body flow is smooth, without stagnation, dead zone, and blockage of the channel. The special feature of this kind of plate is that the width of the flow passage between the plates can reach a unique corrugated shape of 6-12mm. Since there are no obstacles between the flow channels. Even if the pulp fiber in the juice reaches 10 mm in length and 10% in content, it will run smoothly. It can be widely used in waste heat recovery of sewage, sugar making, paper making, textile, food and fruit juice and other industrial fields.

Seed decomposition is one of the important processes of alumina production by Bayer process. The control of decomposition temperature has a great impact on the technical and economic indicators of seed decomposition process and product quality. In particular, China’s alumina plants are located in areas with hot climate and high air humidity. In summer, the temperature difference between the head and tail of the decomposition tank is only 1~2 ℃. Sometimes even “constant temperature” can seriously affect the decomposition rate and product quality. In order to obtain high-quality aluminum hydroxide at a high decomposition rate, aluminum oxide plants usually adopt the decomposition system of gradually cooling the aluminum hydroxide slurry. The main methods are installing cooling water pipes in the decomposition tank for water cooling or spraying cooling with water on the outer wall of the decomposition tank.

The former is easy to scar and difficult to clean. The latter consumes large amount of water, has low cooling efficiency and worsens the surrounding environment. There is also an air channel of about 2m left at the top of the decomposition tank for air cooling. After an aluminum plant adopted this method, the cooling effect is still bad. In the 1980s, the Australian Wagerup Alumina Plant adopted the method of indirect heat exchange between aluminum hydroxide slurry and circulating water to cool down after the sperm agglomerated in the first decomposition tank and decomposed in the second and fourth decomposition tanks. The effect was good and many manufacturers followed suit. The heat exchange equipment used for intermediate cooling includes wide channel plate heat exchanger, spiral plate heat exchanger, and tubular heat exchanger, etc., of which the wide channel plate heat exchanger is recognized as the best among all alumina plants.

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