Mitshbishi MHC steam turbine controls ?

[byrdj]

Mitsubishi 150# servomotor The GVSM has a check valve that relieves between the chambers on either side of the piston. What is it for? I was told this design is similiar to WH

 

[abeltio]

Never heard of it before, but thinking out loud: if it "relieves pressure" is because the designer did not want to have excessive pressure on either side of the piston that could damage the rings... it is better to have some fluid by-pass through a path designed for, than to let it damage the device. what do you think?

saludos.
a.

 

[byrdj]

Here is the GVSM cutaway and the Hydraulic line diagram. I don't have any ideal why it is there. I am not fimilair with this type of turbine controls (mainly worked GE LSTG). I recieved some drawing for this unit and so far figured out how things work.

It looks like it would slow down quick closing GVs! but that don't make sense. pressure under the piston and draining above the piston would have the pressures in the direction for the relief to lift

what do you think?

 

[byrdj]

I guess Engineering com doesn't like pdfs

 

[stgrme]

I don't know all the details of the MHI design, but I do know that in the Westinghouse design, the servomotors in the 150 LB system were double-acting. The valve may be used to balance the forces on either side of the piston once the correct position has been obtained.

Best of luck!

 

[byrdj]

I still would like to hear if the reason for this is known.

Yes the GVSM is double acting (UP to CLOSE), the drawing shows that this valve would relieve the pressure on the lower side of the piston to the upper side of the piston. the spring setting also sees the upper piston side pressure. I can observe that the relief will limit the closing force of the GVSM. I would think that would also reduce the closing velocity.

So I have derived what the drawing indicates it will do, but is that what the design was suppose to do and why would a designer do it?

Also, can anyone open the first files that are pdfs? (I can't)