Application of Spiral Plate Heat Exchanger in Grease Processing

In the process of heating frying oil, the Spiral Plate Heat Exchanger is a heat exchange device that uses high-temperature heat carrier working fluid (heat transfer oil or steam) to rapidly increase the temperature conversion rate of frying oil. The reasonable selection, correct operation and maintenance of this thermal equipment are the key links to ensure that the edible oil reaches the frying temperature required by the process, and meets the requirements of safe continuous, quality and quantity output.

The Spiral plate heat exchanger specially used for heating frying oil is a heat exchange device that uses steam as the thermal medium to heat edible oil. The edible oil absorbs heat through heat exchange to reach the frying temperature required by the production process. This heat exchange process is a typical steam condensation, and the latent heat released by the condensation is absorbed by the edible oil on the other side. Macroscopically speaking, the process is mainly based on the phase change when the steam condenses to provide heat, that is to say, the steam is on the steam side for the entire length The temperature in the spiral channel is constant, and the temperature of the medium on the side of the pasta oil continues to absorb heat along the entire length of the spiral channel until it reaches the outlet of the spiral Plate Heat Exchanger. As far as its heat exchange process is concerned, it is neither a countercurrent operation nor a parallel current operation, and it should belong to the category of cross-current operation.

Saturated steam heating non-phase change fluid (edible oil), should belong to typical condenser operating conditions. Due to the process of exothermic condensation and phase change of saturated steam into liquid, its specific volume, specific heat capacity, thermal conductivity, medium viscosity, etc. will all change significantly, and at the same time release a large amount of latent heat. In terms of heat transfer coefficient, this process is better than that without phase change. The heat transfer coefficient should be large. When the saturated steam condenses, the condensate forms a layer of condensate film on the wall surface, which gradually thickens and then falls along the wall surface, or forms many semi-beaded droplets on the wall surface and gradually condenses into a larger droplet surface. Go down in a row. In engineering, the former is called film condensation, and the latter is drop condensation. According to relevant information, the heat transfer coefficient that can form drop condensation is 10 times larger than that of film condensation. For the spiral plate heat exchanger, because the curvature of the spiral wall is smaller than that of the shell-and-tube heat exchanger, it is possible to form a large-area condensate bead-like droplet flow, and the bead-like droplet flow slides rapidly along the wall surface and is continuously renewed. The wall covered by the condensing film reduces the heat transfer resistance and easily obtains a higher heat transfer coefficient. This is one of the advantages that the heat transfer efficiency of the spiral plate heat exchanger is higher than that of other heat exchangers when used for steam condensation.

Using superheated steam to heat the non-phase change fluid, macroscopically speaking, the heat exchange process should include two states of steam cooling and steam condensation, which obviously adds a non-phase change steam cooling process compared to using saturated steam. That is to say, after the superheated steam enters the spiral plate heat exchanger, it first needs a certain cooling area to absorb its sensible heat. Since this process is carried out before the phase transition is formed, there is no condensate on the wall surface, and its heat transfer coefficient is small. , and its specific heat is also lower than that of liquid, so under the same conditions, the heat transfer efficiency of the spiral plate heat exchanger using superheated steam is far less economical and reasonable than that of using saturated steam.