The back pressure turbine is used for supplying process steam to the facilities in private-use power producers. This type of steam turbine supplies not only electricity but also steam to various process requirements.
Single Cylinder Turbine without any flanged port provision for steam extraction. Total Steam is expanded through the Turbine stages to Generate Power. Exhaust steam from Turbine is connected to the process header. These Turbines are typically useful in Co-generation and Process Let-down Applications.
A controlled extraction at various loading conditions of the turbine based on seasonal variations.
In a controlled extraction type, a control valve integrated with the steam path is provided at a predetermined stage and the steam is allowed to escape the turbine at desired constant pressure based on the process requirement. There are two types of control valves a) A Grid Valve, b) Bypass Valve which control the flow of steam at preset pressure accommodating the seasonal variation of turbine load. The control system works on a closed-loop feedback mechanism. The pressure at the user end is measured and feedback is provided to the control system. Based on this error signal the feedback control system actuates a control valve designed to vary the area of the valve aperture and thereby regulate the pressure. This setup is applied for processes, where the steam pressure is a critical parameter. In some cases, a nozzle/port is provided at a predetermined stage and an un-controlled high-pressure steam flow/bleed is drawn out of the turbine. This tap is provided before the controlled extraction in the steam path of the turbine. Its utility is found typically in LP heating requirements like de-aerator, LP/HP Heaters or some processes.
In an un-controlled extraction type, a tap is provided at a predetermined stage for drawing out the steam for heating solutions.
The un-controlled extraction steam is used for process steam applications (with a smaller quantity of steam flow and set temperature requirements) and LP heating applications like de-aerator for heating solutions.
These turbines can also be deployed in the District heating application.