Characteristics of shell and tube condenser
Advantages of shell condenser: cooling water and tower gas indirect heat transfer, cooling water is not contaminated by oil, so its investment, operating costs and floor space than the direct cooling condenser (plus sewage treatment facilities) is much smaller.
Tubular cooler shortcomings: condensation effect is influenced by water quality, water quality, water pressure, water flow rate is too small (less than 1 m/h), the scale fast, heat transfer rate drops rapidly, therefore, often appear in the device after repair starts early, the tower high vacuum degree, and then with the passage of time, the vacuum degree of reduced gradually. In addition, the temperature of circulating cooling water in some refineries in south China is up to 34~35% in summer, which makes the post-cooling temperature of the condenser on the top of the tower as high as 40%. Therefore, the pressure on the top of the tower is about 9.34~10.674kPa (70~80mmHg), and the extraction rate of reduced pressure distillation is relatively low. In order to overcome these shortcomings, some refineries set up booster pump of condenser cooling water on the top of decompression tower to maintain water pressure and increase the flow rate, set up backwash pipe on the water side of the condenser pipe, and add scale inhibitor at the same time to reduce scaling. 
Because of cross heat transfer, the logarithmic average temperature difference correction coefficient reduces the heat transfer efficiency of the condenser. Because of the existence of close to temperature difference, it is difficult to obtain a lower post-cooling temperature and the consumption of circulating water is high. The structure of baffle leads to relatively high flow resistance loss in process logistics. Therefore, less use in recent years.