When a petrochemical operator wanted to revamp his facility for the production of polyethylene and polypropylene in Brazil, he needed a new top condenser on a distillation column. In the old process, a top condenser was not required, so it was important that the new equipment could be accommodated on top of the column.
Important aspects for the heat exchanger technology selection were process stability, the use of cooling water and low pressure drop on the condensing side in order for condensate removal by means of gravity. Furthermore, the condensate had to be subcooled. A common practice in industry is to do sub-cooling of condensate in an additional heat exchanger. Otherwise the condensate velocity would be very low, leading to low heat transfer coefficients. However, an additional heat exchanger means higher installation costs and more piping. Kelvion convinced the customer that its newly-designed unequal multipass, vertical K°Bloc condenser would provide the best results. This unit combined a condenser and a sub-cooling section in only one. With this unit, the customer saved on installation space and maintenance costs and the efficiency of the process was increased. With Kelvion’s new K°Bloc vertical overhead condenser the two-unit problems have been eliminated. With its special unequal multipass design, the K°Bloc can incorporate the condenser and the sub-cooling section in only one vertical unit with horizontal plates.
‘Unequal multipass’ means that the different passes can have a different number of flow channels, depending on the vapour/liquid mixture percentage. This is the best way of achieving thermal/hydraulic optimization. Heat-transfer efficiency in the condensing and sub-cooling section are now at an optimum level due to the two sections having different numbers of plates and passes enabling the system to adapt the velocity and therefore the heat efficiency to the required values. The advantages at a glance are: ► highest heat-transfer efficiency, thereby reducing the area and cost of the K°Bloc due to the new multipass design; ► a separate sub-cooling section is possible in the same K°Bloc; ► the option of a different number of flow channels; ► strong design of the K°Bloc due to comb liner technology; and ► savings on installation cost, space and piping due to single vertical unit technology. The unit has been working satisfactorily for the customer since 2014.