Principle of turbine quick-shut valve
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The turbine quick-shut valve (TTV valve) is the main and first passage through which steam enters the turbine; it is related to the issue of establishing oil pressure using quick-shut oil and starting oil!
When the quick-shut oil pressure is established, the quick-shut valve is opened and remains open; when the quick-shut oil pressure is removed, the quick-shut valve can be closed rapidly to shut down the machine. The quick-shut valve remains in the open position due to the force of its own spring and the quick-shut oil pressure; once this oil pressure is released, the spring force closes the valve, thereby cutting off the air supply!
The manufacturer’s instructions are very detailed; by reading them more carefully, one can understand everything. I had no prior experience with steam turbines, but now, by studying the instructions and going to the site, I have figured it out.
1. Prepare the starting oil; this oil enters the right side of the quick-shut valve, pushing its piston to move to the left thereby causing the quick-shut valve to close completely； 2. Once the pressure of the oil to be used for starting reaches around 8 kilograms and becomes relatively stable, quickly shut off the oil supply. The oil flowing into the quick-shut valve pushes the piston to the right, causing the quick-shut valve to open fully ； The schematic diagram for the opening control of the quick shut-off valve is shown in the attached figure. 3 Secondary oil: The turbine converts the rotor’s speed into an electrical signal after detecting it via the excitation signal, and this signal is sent as negative feedback to the governor. The governor processes the electrical signal received according to the instructions; this electrical signal is then converted into a hydraulic signal through an electro-hydraulic converter – this is the primary oil pressure. The secondary oil pressure acts on the control valve in order to regulate its opening degree. The closing of the quick-shut valve is controlled by the safety system; if any component in this system triggers a quick-shut action, the pressure of the quick-shut oil is reduced. Under the force of the spring, the piston separates from the piston disc, and the quick-shut oil on the left side of the piston disc is discharged through T1. As a result, the piston disc, along with the valve stem and valve disc, is immediately pushed to the closed position.