Sunday, May 23, 2021

How does a Dynamic Compressor Work?

How does a Dynamic Compressor Work?


A defining feature of dynamic compressors is that they have fast rotating blades. In a dynamic compressor, air introduces between the vanes of the impeller that accelerates it at high speed. Air or gas is released through a diffuser, where kinetic energy is converted into a constant pressure. The most dynamic compressor has radial or axial flow rates. These are often designed for large flow rates. Unlike a positive displacement compressor operating with a positive flow position, the dynamic compressor operates at a constant pressure. Dynamic compressors are more reliable than other types of compressors because they do not have reciprocating components that experience cyclic pressure during service. It often refers to as a turbo compressor because of its ability to produce significant horsepower.

Dynamic compressor mostly uses for large-scale operations. Types of dynamic compressors are centrifugal compressors and axial compressors.

One of the most important factors to consider with a compressor is the efficiency of the compressor at full load. However, the factory air consumption is constantly changing, so a capacity control system is required to ensure stable compressor operation.

Working principle of Dynamic Compressor:

The operation of a dynamic compressor is based on the basics of thermodynamics. First, the air introduces through the inlet of the compressor. As air moves between the blades of the impeller, the impeller blades provide kinetic energy to the air. In this way the wind speed increases. A diffuser connects to the compressor. This diffuser changes the speed of the air under pressure. After that, the air releases through the outlet of the dynamic compressor. Dynamic compressors are well suited for continuous operating conditions due to their narrow operating range.

Types of dynamic air compressors:

1) Centrifugal compressor

Centrifugal compressors pull air toward the center of an impeller and then move it outward toward its edge. There its ides with the diffuser plate and the outlet scroll, where the speed decreases and the pressure increase. Typical centrifugal compressors used for manufacturing water-cooled and use two or three-stage compression. It drives by lubrication bull gears and pinion gears at 50,000 to 75,000 RPM. The full load capacities are overall good (competing with lubrication compressors) and very good compared to other oil-free compressor designs. However, performance can vary significantly with inlet conditions. Heat, low barometric pressure, and high humidity all affect compressors, but not most centrifugal machines.

The latest centrifugal air compressor configuration uses an ultra-fast motor to drive the impeller. This provides a compact compressor without the oil lubrication system attached to the gearbox, making it oil-free and suitable for applications that require 100% oil-free air. 

2) Axial flow compressors

Axial-flow compressor may control large flow volumes in a small housing with favorable power needs. The pressure range of axial compressors is from medium to low. Axial compressors use the same range of turbine blades as a jet engine, forcing air into smaller and smaller spaces. These compressors do not commonly use in industry. This dynamic compressor is lighter and smaller than other compressors. At relatively moderate pressures, these use for constant and high-volume flow rates, for example, in ventilation systems. Due to the high rotational speed, they ideally connect with gas turbines for power generation and propulsion. These compressors design for high reliability, volume, and efficiency applications. Common applications of axial compressors include air separation, sewage treatment, wind tunnel, FCC air blower, blast furnace, etc. Commonly used in aircraft these days.

3) Turbo-expander compressors

A turboexpander, also known as an expansion turbine, is a centrifugal or axial, flow turbine that produces the work used to propel a high-pressure gas diffuser and compressor.

The term "turboexpander" commonly uses to define an expander/compressor machine as a unit. It consists of two primary parts; Radial inflow diffusion and centrifugal (booster) compressor combined as one assembly. Its wheels connect with a single shaft. Expansion turbine power unit and compressor power unit.

In a gas processing plant, the purpose of the turbo-expander is to efficiently perform two different, but admirable tasks on the same machine. The primary task is to efficiently produce refrigerant in the process gas stream.

Advantages and Disadvantages of Dynamic Compressor

Advantages:

  • A dynamic compressor is more reliable than other types.
  • It works with different water currents.
  • It widely uses all over the world.
  • This compressor has an easy design.
  • They lose weight.
  • It requires less maintenance.
  • Oil-free in nature.

Disadvantages:

  • Low efficiency.
  • Dynamic compressor does not compress air by reducing the volume, which is a very familiar method.
  • The dynamic compressor uses one or more rotating elements to accelerate the wind, and then it slows the wind.
  • Increasing, stopping, and suffocating.
  • Very high compression, suitable for limited pressure.
  • They are sensitive to changes in gas composition.

 

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