Sour gas distillation

Summary of technology

Natural gas is the third largest source of the world’s energy requirements after oil and coal, supplying around 20 per cent of global needs. Its uses are varied, including power generation, industrial uses such as chemical production, and residential consumption.

Natural gas is the cleanest burning fossil fuel with lower carbon emissions than coal or oil. It has provided a large portion of new electric power generation capacity, particularly in developed economies where it accounted for nearly 75 per cent of capacity growth between 2000 and 2009. Proven reserves of natural gas represent around 60 years of production at current rates.

Many sources of natural gas contain sour gases such as carbon dioxide and hydrogen sulphide. Sour gases need to be removed before the natural gas is usable. Separating carbon dioxide from natural gases can be difficult because of the tendency for carbon dioxide to form an azeotropic mixture with ethane under typical distillation conditions, which involve high pressure and low temperature.

Our new distillation process removes the methane and C3+ components as a preliminary step, significantly reducing the volume of gas that will require treatment in subsequent steps. This reduces the energy requirements of the process and also reduces the amount of azeotrope inhibiting agent required to control the behaviour of the ethane component.

This improved process can be applied to any natural gas processing plant. Because it requires smaller and less complicated processing equipment than an equivalent plant using existing processes, it makes it economic to locally process smaller natural gas sources

Advantages

This new process offers the following benefits:

  • separate streams of relatively pure ethane, methane and C3+ components mean no further processing is required
  • smaller, less complicated plant required for a given flow rate of feed gas
  • less azeotrope inhibiting agent required to hinder azeotrope formation between ethane and carbon dioxide
  • reduced environmental impact: all separation is achieved by a sequence of distillation columns, so there is no need for chemicals such as amines.

Researchers

Dr. Ahmed Barifcani at the Curtin University School of Chemical and Petroleum Engineering is head of this research.

Stage of development

The process scheme comprises the following separating stages: demethaniser, C3+ separating column, agent 1 addition column, C2 separating column, agent 2 addition column and CO2 separating column. The process scheme has been verified by Hysys simulation.

Intellectual property

Intellectual property is owned by Curtin University. A provisional patent has been filed.

Opportunity

We are looking for a partner such as a LNG plant construction company to collaborate on the next stage of development, which is likely to be a small scale pilot plant.

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