Condensing cum extraction Turbine
Back pressure Turbine
In a condensing turbine, steam is expanded in the turbine until it reaches a very low pressure, and then it is condensed back into water.
In a back pressure turbine, steam is expanded in the turbine until it reaches a predetermined pressure, known as the back pressure.
The condensation of steam at the turbine exit creates a vacuum, which increases the efficiency of the turbine by lowering the back pressure.
The exhaust steam from the turbine is released at a higher pressure, and it is often used for industrial processes where both power and heat are required.
Condensing turbines are often used in power plants where the objective is to maximize the power output from the steam and achieve higher efficiency. The condensed water is usually returned to the boiler for reuse.
Back pressure turbines are commonly used in combined heat and power (CHP) systems, where the steam is extracted at different pressures for various industrial processes, and the remaining steam is allowed to expand through the turbine to generate power.
Condensing cum extraction turbines generally provide higher overall efficiency compared to back pressure turbine.
The combination of condensation and extraction processes allows for better utilization of the available energy in the steam.
Lower over all efficiency
More power out put at same steam inlet
Lower power out put
Power out put reduces by 4 to 5% at same inlet steam flow.
No much effect on power generation if extraction steam consumption reduced, since this steam can be diverted to surface condenser
Power consumption reduces if exhaust steam consumption reduces, since there is no any option to expel the steam to generate power.
Lower temperature of extraction steam around 145 to 155 deg C
High exhaust temperature around 150 to 175 deg C, which is loss
Power can be generated even at no or minimum extraction
Constraints in power generation during no or minimum extraction
Or steam needs to be vented out if electrical power requirement is more.
Auxiliary power consumption of the plant is little bit higher for handling cooling water pumps and cooling tower fans
Auxiliary power consumption is lesser since there is no condenser and hence no cooling water pumps and fans
Initial cost of the project is more due to surface condenser, cooling tower and cooling water pumps
Cost of the project is less as compared to condensing turbines
Heat rate is comparatively more
Heat rate is less since there is no loss of heat in condensers
Operation is little bit critical
Limited extraction steam flow
Exhaust flow will be more since there is no condenser and same steam can be diverted to process as exhaust steam
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