So, I recently started working in a 210 MW Steam turbine generation unit of Dong Fang Turbine works. It is a reheat-regenerative ST with HP-IP-2×LP combination.
Main Steam Pressure=12.1 MPa
While running at 90 MW( due to reduced vacuum), at rated Main Steam pressure, the downstream pressure at four HP governing valve (nameplate shows 'after governing valve pressure') shows 5.1 MPa(at 80% valve opening), and first stage (curtis) chamber pressure shows the same. My query is shouldn't there be a pressure drop at curtis stage nozzle? Why these two pressures are the same?

 

Shawrochis,

Can you supply a diagram of the steam supply system to the HP turbine, including stop valve(s), governing (control) valves, and first-stage turbine nozzles? The diagram should indicate where the various pressure measurements are taken.

Also, if there are extractions (controlled or uncontrolled), they should be evident on the diagram.

If I recall from university, the "Curtis" stage of a turbine is usually the first stage, where a pressure drop and velocity increase occurs through the "nozzle block" (sometimes, if I recall correctly, also called the first stage turbine nozzle). Also, if I recally correctly, there is no further pressure drop through the "Curtis" stage even if there are multiple rotating and fixed turbine blades.

What we don't know is where the pressure measurements taken from. And, what is the "first stage (curtis) chamber"? Is the "chamber" before or after the nozzle ("curtis" nozzle, or first stage turbine nozzle)?

Could it be that there is some drain bypass or drain valve which was inadvertently left open? Again, this should be shown on the turbine steam- and flow drawing(s).

Have you consulted the manufacturer's instructions and/or design manual(s)? If so, what do they say?