For Clear Juice Heating
The Dalton Sugar Mill in South Africa uses plate heat exchangers with 44 plates, each with a heating area of 0.79 m2. The flow rate of the clear juice is 130t/h, heated from 92°C to 104°C, the saturation temperature of the used steam is 111°C, and the heat transfer coefficient is 3400W/m2.K. The pressure drop of the clear juice through the heat exchanger is 76 kPa; when used, the steam valve is not fully opened. That is, the actual temperature difference is still small, and the heat transfer coefficient is also higher. The juice heater is turned on after five weeks of continuous operation, and there is some sludge deposition inside. There is a black film on the plate surface, which is easy to wash away with water.
In the German Nande sugar factory, the amount of beet juice is 600t/h. Before the clear juice enters the evaporation tank, it is heated in 4 stages by 4 plate heat exchangers. The juice vapor of the 1~4 effect evaporation tank is used as the heat source, and the temperature reached by each stage is heated. It is only 3°C lower than the juice vapor temperature and finally reaches 127°C.
For Mixed Juice Heating
The Dalton Sugar Mill in South Africa uses a plate heat exchanger to heat the mixed juice, 50 pieces. Use two months, clean once a week, cane juice flow 103 ~ 130t / h, from 72 ~ 76°C heating to 94 ~ 97°C, the use of waste steam saturation temperature of 109 ~ 111°C, heat transfer coefficient of 2900 ~ 3380W /m2.K, the pressure drop of the cane juice is 0.05-0.1 MPa. When the machine is shut down, the interior is deposited by sediment and sugarcane, and there is a thin layer of scale on the board surface, but less than the tube heater, it can be washed with water and brushed. Each work shift is “backwashed” and some of the sediment can be washed away. However, it is preferable to remove the fibrous impurities in the cane juice by sieving.
For materials containing more solid suspended solids such as mixed juice, the use of a wide flow channel plate heat exchanger is better. A foreign sulfite process sugar factory, using this heat exchanger and the third effect evaporation juice steam heating mixed juice and sulfur smoked juice, can run continuously for 30 days, the juice pressure used is very low, only 40kPa absolute pressure, The steam temperature is 75°C. The heat transfer coefficient reaches 2090~2440W/m2.K, and its heating area is less than half of the tube type.
Two beet sugar factories in Poland (more than 2,000 tons of beet processed per day), in the mid-1990s, used a wide-gap plate heat exchanger, using the juice vapor of the boiling sugar can (temperature about 60°C) to heat the exudation juice, by The temperature was raised to about 50°C at about 30°C, then ash was added and heated again to about 88°C with steam and third juice. It works well and can be used continuously for one season. After shutdown, it can be sprayed with high-pressure water to remove all deposits on the surface of the sheet. It utilizes a large number of low temperature heat sources to significantly reduce the fuel consumption of the sugar mill.