Diffuser of rotating fluid machines

Abstract

A diffuser of a rotating fluid machine that processes a gas with high level of contaminants is provided, the diffuser having an annular surface portion facing rotating vanes of a rotor of the rotating fluid machine, the annular surface portion being at least partially covered with an abradable and anti-encrustation coating including (A) a first lower metal-based coating layer applied on the annular surface portion of the diffuser, and (B) a second upper polymer-based coating layer applied on the first lower metal-based coating layer, wherein the first lower metal-based coating layer comprises 99% by weight of aluminum powder based on the total weight of the first lower-based coating layer and is anchored to the annular surface with a nickel and aluminum (NiAl) binder.

1 . A diffuser of a rotating fluid machine that processes a gas with high level of contaminants, the diffuser comprising:
 an annular surface portion facing rotating vanes of a rotor of the rotating fluid machine, the annular surface portion being at least partially covered with an abradable and anti-encrustation coating including (A) a first lower metal-based coating layer applied on the annular surface portion of the diffuser, and (B) a second upper polymer-based coating layer applied on the first lower metal-based coating layer;   wherein the first lower metal-based coating layer comprises 99% by weight of aluminum powder based on the total weight of the first lower-based coating layer and is anchored to the annular surface with a nickel and aluminum (NiAl) binder.   
     
     
         2 . The diffuser according to  claim 1 , wherein -a the thickness of the second upper polymer-based coating layer ranges from 1 mm to 1.5 mm. 
     
     
         3 . The diffuser according to  claim 1 , wherein -a the thickness of the second upper polymer-based coating layer is about 1.2 mm. 
     
     
         4 . The diffuser according to  claim 1 , wherein the thickness of the first lower metal-based coating layer ranges from 1 mm to 1.5 mm. 
     
     
         5 . The diffuser according to  claim 1 , wherein the second upper polymer-based coating layer is a thermoplastic fluoropolymer. 
     
     
         6 . The diffuser according to  claim 5 , wherein the thermoplastic fluoropolymer is ethylene-chloro-trifluoroethylene. 
     
     
         7 . The diffuser of  claim 1 , wherein the first lower metal based-based coating layer adheres to the annular surface portion to resist a stress value over 40 MP.