General Knowledge of Diaphragms in Centrifugal Compressors
1. Definition of Centrifugal Compressor Diaphragm
A diaphragm forms the gas flow passage for stationary components inside a centrifugal compressor.
Conduct visual inspection on diaphragms for defects such as corrosion, cracks and material spalling. Thoroughly clean the diaphragm and perform surface dye penetrant inspection.
Diaphragms and diaphragm grooves shall be free from deformation, corrosion, erosion and other traces. The diaphragm shall slide smoothly inside the groove.
2. Classification of Diaphragms by Installation Position
According to their positions inside the compressor, diaphragms are categorized into four types:
Inlet diaphragm: installed at the inlet of the first impeller of each compression section;
Outlet diaphragm: installed at the outlet of the last impeller of each compression section;
Inter-stage diaphragm: arranged between two compression sections;
Intermediate diaphragm: mounted in the middle of each section to form diffusers, return bends and return channels.
3. Functions of Diaphragms
The inlet diaphragm forms an inlet chamber together with the cylinder to guide gas to the inlet of the first-stage impeller.
The outlet diaphragm acts as the final-stage diffuser and outlet chamber.
The inter-stage diaphragm serves to separate the outlet or inlet of two adjacent compression sections.
The intermediate diaphragm has two functions: first, forming a diffuser to convert the kinetic energy of gas discharged from the impeller into pressure energy; second, constructing return bends and return channels to divert gas from the diffuser and guide it into the next-stage impeller for further compression.
Forged steel must be adopted for inter-stage diaphragms bearing heavy loads.
4. Common Materials for Diaphragm Manufacturing
Most diaphragms of centrifugal compressors are made of cast iron or ductile iron. These materials can be easily cast into the complex shapes required for diaphragms while offering relatively high strength.
5. Precautions for Diaphragm Disassembly and Assembly
During disassembly and assembly, ensure no debris, tools or other foreign objects fall into the cylinder and pipelines.
Apply an even layer of molybdenum disulfide inside the diaphragm groove during assembly. The axial and radial fit between the diaphragm and cylinder body shall be neither loose nor over-tight to avoid cylinder collision. The horizontal split joint of the diaphragm shall be tightly fitted; a 0.01 mm feeler gauge shall not be insertable into the clearance.
A diaphragm forms the gas flow passage for stationary components inside a centrifugal compressor.
Conduct visual inspection on diaphragms for defects such as corrosion, cracks and material spalling. Thoroughly clean the diaphragm and perform surface dye penetrant inspection.
Diaphragms and diaphragm grooves shall be free from deformation, corrosion, erosion and other traces. The diaphragm shall slide smoothly inside the groove.
2. Classification of Diaphragms by Installation Position
According to their positions inside the compressor, diaphragms are categorized into four types:
Inlet diaphragm: installed at the inlet of the first impeller of each compression section;
Outlet diaphragm: installed at the outlet of the last impeller of each compression section;
Inter-stage diaphragm: arranged between two compression sections;
Intermediate diaphragm: mounted in the middle of each section to form diffusers, return bends and return channels.
3. Functions of Diaphragms
The inlet diaphragm forms an inlet chamber together with the cylinder to guide gas to the inlet of the first-stage impeller.
The outlet diaphragm acts as the final-stage diffuser and outlet chamber.
The inter-stage diaphragm serves to separate the outlet or inlet of two adjacent compression sections.
The intermediate diaphragm has two functions: first, forming a diffuser to convert the kinetic energy of gas discharged from the impeller into pressure energy; second, constructing return bends and return channels to divert gas from the diffuser and guide it into the next-stage impeller for further compression.
Forged steel must be adopted for inter-stage diaphragms bearing heavy loads.
4. Common Materials for Diaphragm Manufacturing
Most diaphragms of centrifugal compressors are made of cast iron or ductile iron. These materials can be easily cast into the complex shapes required for diaphragms while offering relatively high strength.
5. Precautions for Diaphragm Disassembly and Assembly
During disassembly and assembly, ensure no debris, tools or other foreign objects fall into the cylinder and pipelines.
Apply an even layer of molybdenum disulfide inside the diaphragm groove during assembly. The axial and radial fit between the diaphragm and cylinder body shall be neither loose nor over-tight to avoid cylinder collision. The horizontal split joint of the diaphragm shall be tightly fitted; a 0.01 mm feeler gauge shall not be insertable into the clearance.
