A large amount of secondary juice steam will be produced in the process of sugar boiling in sugar factories. The contact condenser is often used in old sugar factories to directly mix the circulating water and juice steam. The heat of juice steam is transferred to feed water, and the temperature of circulating water rises.
With the increasingly strict environmental protection policy, the disadvantages of this design appear. After long-term use, due to the direct contact between the circulating water and the juice steam, the COD of the circulating water gradually increases, and the viscosity of the circulating water becomes larger and larger, which requires a lot of cost to treat these circulating water. Therefore, the advantages of non-contact condenser in this condition will appear.
But in the design process of the condenser in sugar factory, there is a big difference with the conventional condenser design, which is mainly caused by the following aspects.
1: The content of non condensable gas in the juice steam of sugar factory is high, so we often ignore the influence of non condensable gas on condensation heat transfer in conventional condenser design, but sugar factory often can’t ignore it.
2: The sugar factory has the risk of running away sugar, so there may be a small amount of syrup in the secondary juice steam.
3: Sugar factory has strict requirements on the pressure drop of condenser steam side. If the pressure drop of condenser steam side is large, or the pipeline is small, the resistance loss along the way is large, the secondary steam can not enter the condenser.
In view of the above problems, the following problems should be paid attention to in the design process of the condenser in sugar factory
1: The influence of non condensable gas on the heat transfer coefficient must be considered. The design can be based on 95% steam + 5% air. K value can be 800-1300 (special plate condenser) according to experience. It’s about a third of conventional condensation.
2: The pressure drop of condensation side is less than 8KPa.
3: Add the juice catcher before the secondary steam enters the condenser.