What is a Gas plant

Oil and gas reserves are found deep below the earth's surface and they are brought to the surface through piping that runs the entire depth of the well. In a gas field, the gas is generally mixed with associated gas, oil, production water, moisture and other contaminants. The raw natural gas, with associated gases and impurities produced by a gas field, is gathered and collected in a gas plant. In the same gas plant, this impure gas is treated, dehydrated, processed, cleaned so as to remove moisture and contaminants and to recover the heavy fractions. The treated gas in liquid or solid or gaseous form can then be transported via pipeline to areas of application directly or stored and ready to be shipped via pipeline or oil tanker.

How it works?
Depending on the gases, there are different gas plants. Each gas plant follows different processes depending on their properties. However, certain steps involved in processing remains more or less the same.

In a gas plant, the crude gas is dehydrated and processed through molecular sieves, acid gas removal, and chilling units. The crude gas is first sent to a gas separation system where its pressure is reduced in different stages. In each decompression stage, the associated gas or contaminant is released in a separator until the pressure is fully reduced to little above atmospheric pressure. The gas is then sent to the stabilizer column where it is heated and cascaded through a series of molecular sieves spaced throughout a column. The final output-in this case the gas in liquid or solid form-is collected at the top of the column, while the heavy crude and impurities is drawn off from the bottom. The stabilized gas is then cooled and stored. It is to be noted that both cryogenic and non cryogenic techniques are used to produce gas. While the cryogenic process is popular for large sized plants, the non cryogenic process involving PSA and VPSA technique has also become popular in recent years and used in small sized plants. The main purpose of a gas plant is to ensure that the entire operation is perfectly balanced so that it gives the maximum efficiency and simplicity in operation.

Gas storage plant
Once the gas produced in a gas plant has reached the market area, it may not always be needed immediately. Therefore there is the need of storing gas for future use by gas distribution companies so as to prevent unforeseen supply shortages.

How it works?
The gas is usually forced into underground storage facilities usually consisting of depleted gas fields, salt caverns or aquifers located near the point of gas usage.
There are essentially two types of storage facilities:

• Base load storage facilities: They meet seasonal demand variations. They are large sized reservoirs in order to provide a steady supply of gas. The most common type of base load storage facility is the depleted gas reservoir.
  
  
• Peak load storage facilities: These storage facilities provide high delivery capacity for short periods of time. They meet quick, sudden, short-term increases in demand. They are small in size and can be replenished in a shorter time compared to base load facilities.

Things to consider before setting up of gas plants and factories.

• Preparation of preliminary reports
• Preparation of drawings and site layouts
• Foundation drawings · Measurements
• Survey Equipment selection
• Framing technical specifications
• Selection of suppliers
• Design & Manufacturing
• Erecting & Commissioning
• Storage, filling and distribution
• Training of people at site for operating in plants
• Skilled and semi-skilled technical manpower, engineers and operators

Types of gas plants
Depending on various gases available and different processes to produce the final output, there are different gas plants. Some of the popular types of gas plants are as follows:

Oxygen plant Nitrogen plant Hydrogen plant Acetylene plant Carbon dioxide plant Nitrous oxide plant Dry ice plant Cryogenic liquid plants Oxygen liquid plants Air separation plant

Cryogenic oxygen plants Cryogenic nitrogen plants PSA Nitrogen Gas Plants PSA Oxygen Gas Plants LNG plant Biogas plant Natural Gas Plant CNG Plant Methane Gas Plant