Back-pressure steam turbine cogeneration system - continued.

It is also possible to extract steam from intermediate stages of the steam turbine, at a pressure and temperature appropriate for the thermal load. After exiting from the turbine, the steam is fed to the load, where it releases heat and is condensed. The condensate returns to the system with a flow rate which can be lower than the steam flow rate, if steam mass is used in the process or if there are losses along the piping. Make-up water is used to make up for the lost steam or condensate.

The back-pressure system has the following advantages:

a. Simple configuration with few components.

b. The costs of expensive low-pressure stages of the turbine are avoided.

c. Low capital cost.

d. Reduced or even no need of cooling water (because no condenser is used).

e. High total efficiency, because there is no heat rejection to the environment through a condenser.