Today, the global supply and demand for liquefied natural gas (LNG) is approximately 300 million tons per annum (MTPA). Over the next five to ten years, demand is predicted to surpass supply. With such high use expected, LNG is a valuable commodity, commanding high market prices and delivering soaring profits to suppliers. That said, equipment used in the LNG production process needs to provide extended, reliable operation with maximum uptime and output.
Gas turbines are widely used as mechanical drives when compressing refrigerants as part of the LNG process. If a gas turbine used in the liquefaction process has unscheduled downtime, it can cost the LNG plant owner several million dollars a day in lost production. In fact, a single unscheduled turbine shutdown could result in the entire LNG train being taken offline, requiring lengthy shutdown and start-up procedures leading to huge financial losses.
Let's examine challenges faced by LNG turbine operators, factors that hinder turbine performance, and choosing filtration systems based upon operating conditions.
The challenge: keeping problems out of the turbine
Land-based refrigerant compressor stations are often located near coastlines for easier tanker access. LNG processing facilities may also be located on floating vessels for close proximity to offshore gas fields. In either case, gas turbines used in the oil and gas industry encounter extremely challenging operating environments. High levels of small particulate in the form of sand, dust and shot-debris from drilling, salt aerosols, and harsh weather conditions all threaten the performance and health of a gas turbine. Failure to address these contaminants can lead to reduced performance, expensive repairs, and eventually could cause a catastrophic failure of the turbine components.
The solution: inlet filtration
To protect the turbine from corrosion, erosion and fouling and keep it operating reliably and predictably over long periods of time, a carefully designed inlet filtration system is required. However, considering the massive volume of air passing through a gas turbine inlet, installing the correct system for the application conditions is critical. A filtration system that is correctly designed and engineered to meet the real-world conditions of the gas turbine installation, can mean shutdowns are limited to only scheduled maintenance periods. Choosing the wrong system can result in major financial repercussions.
Filtration system design
Typically, the filtration systems will incorporate multiple stages, sometimes as many as five. They will often include:
Prefilter stages: designed to remove larger particles and protect the higher efficiency filtration stages.
Coalescers: to remove liquid contaminants
Final filter Stages: To remove fine particulate and ensure clean air to the gas turbine, the materials used here are to be selected to meet the specific needs of the installation. This can include hydrophobic media and extended depth media.
Partnering with an expert in the specialized design of filtration systems for gas turbine protection, such as Parker Hannifin, can help to assure all considerations are met. Parker offers a range of filtration materials and engineering expertise for gas turbine protection.
It is widely accepted that an inlet filtration system is crucial for the reliable operation of gas turbines. Using the skills of leading experts in the field will help LNG suppliers take advantage of developing and improving filtration technology, thereby keeping their equipment running at optimum performance levels.
This article was contributed by Peter McGuigan, global LNG market manager, Parker Gas Turbine Filtration Division