Streamline coal slurry letdown valve

Claim 1

A high pressure coal slurry letdown valve, comprising: means defining a high pressure cylindrical flange valve inlet and a low pressure cylindrical flange valve outlet, said outlet including a stepped cylindrical bore including an internal recess for slidably receiving and locating a valve seat means and wherein the central axis of said inlet and said outlet are disposed at generally right angles to one another; means defining a streamlined arcuate coal slurry flow path disposed between said inlet and said outlet; two-piece valve seat means defining a valve throat, said seat means including a first member having a downstream divergent flow path and adapted to slidably seat within said bore against said internal recess and having a flat upstream end surface transverse to said flow path, and a second member separate from said first member slidably fitted in said bore in abutting end contact with the flat end portion of said first member defining a convergent upstream portion of said seat means; a biased cage including at least two pillars fixedly disposed within said flow path opposite said inlet, said cage having at least two truncated conical surface portions between said pillars adjacent said valve inlet to provide streamlined surfaces generally conforming to the streamlined arcuate flow path means between said inlet and said outlet, said cage having an end portion in contact with said seat means second member to hold said seat means in said recess; and a plug movably disposed within and slidably supported by said biased cage for controlling flow of coal slurry through said valve throat.