Condensing unit means a system in a steam turbine system that is used to reduce the pressure created during the operation of the steam turbine. The pressure reduction in steam turbine comes from condensing unit which reduces the boiler pressure by condensing the steam present in the turbines. Pressure reduction in steam turbine allows you to increase or decrease the speed of the turbine by a factor of two, which results in a considerable increase in the operational efficiency of the turbine. In some cases, pressure reduction in steam turbine is so significant that in a steam turbine the pressure is reduced to less than 100psi. This concept is known as Single Stage Steam Turbine, or SSTT.
Several problems come with the usage of the condensing unit. Primarily, condensing unit reduces the overall steam pressure and creates more cross-sectional area in steam which in return create more friction in the steam turbine. So you can easily see, the result is a lower overall steam pressure, more heat loss through the steam and a higher pressure at the point of friction. The second problem is that during operation of the condensing unit, the turbine becomes to be damaged by hot steam and the condenser releases hot steam. However, this problem can be solved by using multiple condensing units within a system. Steam turbine system with multi-stage condensing unit will make your turbines more efficient. Also it will help in increasing your operational efficiency.
Another drawback of condensing unit is that the efficiency of the steam turbine decreases with the number of condensing units. So, it is better to use multi-stage condensing unit, which increases the efficiency of the turbine. All of the above mentioned problems come with condensing unit and steam turbine. You should use different condensing units if your turbine is multi-stage. Multi-stage condensing unit will improve the efficiency of the turbine, and also you will get better performance from your turbine.