PNEUMATICS Chapter 3 ROTARY COMPRESSORS RBTC-1359-01

Objectives Classification Vane Compressors – Rotary Screw Positive Displacement Dynamic Vane Compressors – Rotary Screw Low Pressure High Volume Diaphragm Centrifugal

Objectives Continued Axial Flow Selection of Compressor Capacity System Compressor Checking Accessories Packaged

Introduction There are 2 types of compressors: Positive Displacement Rotary Compressors with mechanically separated inlet and discharge ports are PD Include Sliding Vane, dry and wet screw, liquid-ring, impeller (lobe) types Dynamic No method of separating inlet and discharge ports Centrifugal and axial flow

Vane Compressors The Sliding vane is a rotary, PD Compact, less efficient than piston but more efficient than other rotary compressors Resemble vane pumps but are larger Consists of a rotor mounted off center in a round casing The rotor has rectangular slots Negative pressure draws in suction Space becomes continuously smaller as it turns Single vanes max p = 50 psig – 2 stage = 125 psig

Compressor Valves

COMPRESSOR SKID

Compressors

THEORY

COMPRESSION Means increasing gas pressure from a low pressure to a high pressure Most common type – Gas engine driven reciprocal From 50 to 15,000 HP Also driven by electricity Also driven by turbines

COMPRESSOR PARTS

RECIPROCATING COMPRESSION

VALVES

INTEGRAL COMPRESSOR

CROSSHEAD

INTERNALS

MOVEMENT

VALVES

TURBO EXPANDER

NGL PLANT – Low Temp – 40°F

CENTRIFUGAL COMPRESSORS Multi stage Dynamic Inlet Impellers vary in size In the eye Low suction pressure Outlet – higher kinetic energy Impeller housing 150,000 cfm, 150 psi – 3000 to 12,000 rpm Higher HP Motor required

Centrifugal Controling Throttling