Gas to Liquid Plant Details

 

Overview of the Gas to Liquid (GTL) Process

A Gas-to-Liquid (GTL) plant requires several vital inputs, including pipeline-quality natural gas, 90% purity oxygen (O2), clean water, and electricity. Since each site has unique characteristics, conducting a site survey by an EPC (Engineering, Procurement, and Construction) firm is a recommended first step once serious interest in constructing a GTL plant has been established.

Key Requirements:

  • Pipeline Quality Natural Gas: The natural gas supply can come from various sources, such as a pipeline, a commercial gas supplier, a renewable gas source, or directly from a gas well, provided the gas meets specified quality standards. The G-Reformer® console continuously monitors the composition of the input gas in real time, which is especially critical for non-commercial gas sources. Pre-treatment might not be necessary if the gas falls within the acceptable range for sulfur compounds as found in commercial natural gas. For well-head gas, a certified fuel sample analysis is crucial to determine its suitability, and in some cases, more energetic gases can enhance production efficiency.
  • Oxygen: The plant requires 90% purity oxygen. For a single G-Reformer® system, liquid oxygen (LOX) can be delivered from a local supplier, eliminating the need for on-site oxygen generation. However, for larger plants (more than one G-Reformer®), an oxygen-concentration plant will be necessary. Various oxygen concentration technologies are available, which tend to become more economically efficient as plant size increases.
  • Clean Water: Essential for the production process.
  • Electricity: Required to power the GTH plant operations. Options exist to co-generate electricity where grid power is unavailable.

System Operation and Control

The G-Reformer® system is controlled via a custom-built control console developed by GWTI. This console allows for remote monitoring and control, including monitoring natural gas input composition and taking autonomous action, such as shutting down the system if necessary. In its initial stage, the G-Reformer® produces a mixture of hydrogen and carbon monoxide, known as SYNGAS. This SYNGAS is carefully monitored and controlled for the subsequent stages of the GTL process.

GTL Process Overview:

  1. Initial Reforming Stage: The G-Reformer® begins by converting natural gas into a mixture of hydrogen, carbon dioxide, and carbon monoxide. This initial stage sets the foundation for the subsequent processes.
  2. Cooling and Compression Stage: After leaving the G-Reformer®, the SYNGAS is cooled, and the captured heat is repurposed for other plant functions, such as steam generation. The SYNGAS is then compressed and reheated for input into the Fischer-Tropsch (FT) unit.
  3. Fischer-Tropsch (FT) Stage: The FT unit is a well-established technology that converts SYNGAS into liquid products based on the unit’s design and catalyst used. GWTI has developed a specific catalyst tailored for GTL applications. This stage converts the SYNGAS into a liquid that contains high-purity “tech-grade” water and a mixture of organic chemicals, including a high-cetane diesel blend stock. Unlike other GTL processes, GWTI’s design eliminates waxes in the output. The diesel blend stock is highly pure because it is derived from natural gas rather than refined from crude oil, making it ideal for blending with lower-grade diesel to improve cetane ratings and meet air quality standards.
  4. Separation Stage: After leaving the FT unit, the liquid is separated into various components. The water and associated alcohols are separated, and the water-borne alcohols are removed, leaving ultra-pure “tech water.” The remaining chemicals are separated from the blend stock diesel fuel. The GTL process yields a high-purity diesel blend stock and several organic chemicals. The chemicals produced are highly pure, making them valuable in various industries. Currently imported from China and refined from crude oil, these chemicals can now be produced domestically with superior purity using GWTI’s GTL process. The liquid products can be separated on-site using separation towers or transported for further processing elsewhere. This GTL process significantly increases the value of natural gas by converting it into easily transportable liquid products, eliminating the need for pipelines.

Environmental and Economic Benefits:

The GTL process creates extremely low airborne carbon emissions, as virtually all carbon is embedded in the produced liquid hydrocarbon chemicals. The chemicals produced are highly pure, made from natural gas rather than oil. The value of the offtake liquids of the GTL process is tens of times more than the cost of the input natural gas. Most chemicals are made from oil in China and imported into the USA. Benefits include eliminating flaring or venting natural gas in oil production, monetizing stranded natural gas, and eliminating leaking natural gas from decommissioned or capped oil wells or coal mines. Independent of the natural gas source, the chemicals produced are worth many times more than the input value.