What is a Compressor? - PowerPoint PPT Presentation

1 / 17
About This Presentation
Title:

What is a Compressor?

Description:

What is a Compressor? A mechanical device that increases the pressure of a gas by reducing its volume. Similar to a pump Increases the pressure on a fluid and ... – PowerPoint PPT presentation

Number of Views:2932
Avg rating:3.0/5.0
Slides: 18
Provided by: JohnSk151
Category:

less

Transcript and Presenter's Notes

Title: What is a Compressor?


1
Compressors
  • What is a Compressor?
  • A mechanical device that increases the pressure
    of a gas by reducing its volume.
  • Similar to a pump Increases the pressure on a
    fluid and transport it through a pipe.
  • What is key difference between a Fluid and a Gas?
  • Compressibility a gas is compressible
  • What happens to gas volume as it is compressed?
  • Decreases
  • What happens to the Temperature of the Gas as it
    is compressed?
  • Increases

2
Compressors
  • Compressors are classified by how they work
  • Two Categories of Compressors
  • Positive Displacement
  • Dynamic
  • What is a Positive Displacement Compressor?
  • A compressor that confines successive volumes of
    gas within a closed space in which the pressure
    of the gas is increased as the volume of the
    closed space is decreased.
  • Intermittent Flow
  • What is a Dynamic Compressor?
  • A compressor using a rotating mechanism to add
    velocity and pressure to gas.
  • Continuous Flow

3
Compressors
  • Two types of Positive Displacement Compressors
  • Reciprocating
  • Rotary
  • Two Types of Dynamic Compressors
  • Centrifugal
  • Axial

4
Compressors
  • Reciprocating Compressors
  • How does it work?
  • Piston movement in a cylinder connected to a rod
    and crankshaft
  • Downward piston motion, low pressure gas enters
    the chamber
  • Upward piston motion, gas is compressed and exits
    the chamber
  • Video

5
Compressors
  • Reciprocating Compressors
  • High Horsepower Applications
  • Common in natural gas transmission lines.
  • Processes for high pressure delivery of gasses
  • Air Conditioning Compressors
  • Some manufactures (Frigidaire) use rotary
    compressors
  • AC Compressors (and other small appliance
    applications) are Hermetic or Semi-Hermetic

6
Compressors
  • Hermetically Sealed and Semi Hermetically Sealed
    Compressors
  • The compressor and motor driving the compressor
    are integrated, and operate within the
    pressurized gas envelope of the system.
  • The motor is designed to operate and be cooled by
    the gas or vapor being compressed.
  • The hermetic uses a one-piece welded steel casing
    that cannot be opened for repair.
  • If the hermetic fails it is simply replaced with
    an entire new unit.
  • A semi-hermetic uses a large cast metal shell
    with gasketed covers that can be opened to
    replace motor and pump components.
  • The primary advantage of a hermetic and
    semi-hermetic is that there is no route for the
    gas to leak out of the system.
  • Open compressors rely on either natural leather
    or synthetic rubber seals to retain the internal
    pressure
  • Require a lubricant such as oil to retain their
  • sealing properties

7
Compressors
  • Rotary Compressors
  • How do they it work?
  • When a rotating mechanism spins past the inlet
    valve, it creates a vacuum.
  • The fluid flows out of the valve behind it,
    filling the vacuum.
  • As it approaches the outlet valve, the chamber
    shrinks, creating more pressure on the fluid.
  • The fluid has nowhere to go but out of the outlet
    valve, so it shoots out of it.
  • Then the rotating mechanism continues on to draw
    more fluid at the inlet valve.
  • How it works Video

8
Compressors
  • Common Types of Rotary Compressors
  • Screw
  • Vane
  • Scroll
  • Screw
  • Two meshing helix screws
  • Rotors
  • Compact and smooth running
  • 2 types - Oil Free and Oil Flooded
  • Oil Free No assistance from oil to cool and
    assist in sealing .
  • Oil Flooded Oil injected to aid in sealing and
    provide cooling.
  • Separator downstream to capture the oil

9
Compressors
  • Vane Compressors
  • Vane housing on a off centered shaft
  • Vanes slide in an out always making contact with
    the compressor walls
  • Gas enters in the largest opening
  • Exits the smallest
  • Good for low pressure applications
  • Efficient
  • Heat controlled by
  • oil injection

10
Compressors
  • Scroll Compressor
  • How it works
  • 2 Spirals
  • 1 stationary, 1 orbits without rotating
  • 1st orbit entraps inlet gas
  • Subsequent orbits compresses gas and exited out
    the center
  • Generally 2-3 orbits for a full cycle
  • Video
  • Advantages
  • Compact
  • Steady flow
  • Low energy use
  • Quiet
  • Smooth operation

11
Compressors
  • What is a Dynamic Compressor?
  • A compressor using a rotating mechanism to add
    velocity and pressure to gas.
  • Continuous Flow
  • What are the Two Types of Dynamic Compressors?
  • Centrifugal
  • Axial

12
Compressors
  • Centrifugal Compressors
  • Rotating disk (impeller) forces gas to the rim
    of the impeller, increasing velocity
  • The diffuser converts the velocity energy to
    pressure energy.
  • Primarily used for continuous, stationary service
    in industries such as refineries, chemical plants
    and snow making operations
  • Single Stage and Multi-Stage Compressors
  • How a Centrifugal Compressor Works

13
Compressors
  • Impeller
  • Most critical part of a centrifugal compressor
  • Compressor performance determined by impeller
  • Size
  • Shape
  • Speed
  • 3 types of Impellers
  • Closed
  • Most common
  • Shroud covering both sides of the blade
  • Center eye hole for gas to enter
  • Used in Multi-stage compressors
  • Semi open
  • Open

14
Compressors
  • Multi-Stage Compressors
  • Diaphragm
  • Specially designed casing wall separating the
    stages
  • Gas passes through the difuser
  • Passes through the return channel in the
    diaphragm
  • Controlling Axial Load on the Shaft
  • Bearing Review
  • Thrust Bearing

15
Compressors
  • Axial Compressors
  • Gas flows parallel to the axis of rotation
  • Unlike centrifugal that has radial components
  • Has rotating and stationary components
  • Rotating airfoil rotor
  • Stationary airfoil stator
  • Similar number of these on
  • a shaft
  • Video

16
Compressors
  • Axial Compressors
  • High Volume
  • High Efficiency
  • High Cost
  • Common Uses
  • Gas Turbines
  • Jet engines
  • Power stations
  • Nickname Superchargers

17
Homework
  1. What is a Compressor?
  2. What happens to the temperature and the volume of
    a gas as it is compressed?
  3. What are the 2 categories of Compressors?
  4. Explain the difference between a positive
    displacement and radial compressor.
  5. Explain how a reciprocating compressor works.
  6. Describe a Hermetically sealed compressor.
  7. Explain how a rotary compressor works.
  8. Describe how a scroll compressor works.
  9. Explain how a multi stage compressor works.
  10. What type of compressor is found on jet aircraft?
Write a Comment
User Comments (0)
About PowerShow.com