Raw natural gas contains impurities that must be extracted before further processing. Typical impurities include carbon dioxide, water, hydrogen sulphide, ethane, methane and butane, as well as volatile organic compounds like benzene, ethylbenzene, toluene and xylene. The impurities in gas are removed via a series of processes, and some of these involve using heat transfer fluids. Selecting the correct heat transfer fluid is always based on several different factors and often involves technical support from an expert in heat transfer fluids.
Picking the right heat transfer fluid for an application
The key consideration when selecting a heat transfer fluid is the solution’s operating temperatures. The fluid’s start-up temperature should always be defined at the point of pumpability. The dedicated pumpability point is defined as the temperature when fluid’s viscosity is approximately 300 centistokes. The maximum operating temperature for bulk fluid desired is important to assess which type of fluid is deployed. The autoignition temperature and flashpoint are used to set up safety procedures and guidelines.
A critical issue in colder climates is the pumpability point. An increasing demand exists in areas like Russia, Canada and parts of the US for gas processing, where sometimes temperatures can drop to –45°C over the winter months. Some heat transfer fluids operating at low temperatures have exceptionally high viscosities. This makes both start-up and shipping problematic, and is when the pumpability point of a heat transfer fluid becomes crucial.
The most common heat transfer fluids used in gas processing plants are mineral oil based. However, new synthetic-based fluids may also be employed, depending on the maximum bulk operating temperatures desired and required. Mineral oil heat transfer fluids are used generally up to 316°C, while a synthetic fluid can be used at temperatures exceeding 316°C and, in some other cases, up to temperatures as high as 399°C. Both synthetic and mineral oil-based heat transfer fluids are favoured in gas processing applications due to the high flashpoints, low vapour pressures and high autoignition temperatures they offer.
Kerosene and diesel are also occasionally utilised as part of petrochemical processes. However, they have some disadvantages that can make them difficult to deploy. Both these fuels have low autoignition points and flashpoints, which makes them highly combustible fluids requiring additional health and safety precautions. Additionally, they have far higher vapor pressures when working at higher operating temperatures compared to synthetic and mineral heat transfer fluids. As a result, they vaporise faster which means more frequent fluid change intervals for the system.
Advanced heat transfer fluids for gas processing operations
For gas processing operations, leading manufacturers like Paratherm offer cutting-edge heat transfer fluids, along with technical services and specialist liquids designed to keep systems clean.
For instance, the Paratherm HR Heat Transfer Fluid is a fully synthetic and aromatic-based solution that has an upper temperature range of 357°C. As a result, it can be counted upon of most intense refining and distillation applications in the industry.
Paratherm™ GLT is another synthetic aromatic heat transfer fluid from the manufacturer. However, it is designed for applications with a different temperature range. It has proven to deliver durable and long-lasting service at temperature of up to 301°C. It also has a far lower start-up temperature than heat transfer fluids using a mineral oil base (1-7°C).
With an understanding that gas processing operations must remain compliant with government and environmental regulations and adhere to their own company policies regarding protecting our natural world, Paratherm has developed fluids to answer these challenges.
For example, gas processing plants that are looking for biodegradable and non-toxic heat transfer fluids where there could be cold-start needs and environmental concerns can opt for Paratherm MR. This fluid can operate at temperatures of up to 288°C and has a minimum start-up temperature of 3°C, along with a minimum operating temperature of 2°C.
Paratherm™ NF is another non-fouling and non-toxic heat transfer fluid produced by the firms and enjoys max recommended operating temperatures of up to 316°C when used in fired heaters, as well as an excellent minimum start-up temperature (-5°C).
The company also offers specially engineered system-cleaning liquids for different gas processing applications where heat transfer oils are deployed. These include options for cleaning mineral oil systems in operation and overnight, as well as solutions for cleaning systems using synthetic and aromatic heat transfer fluids, like those mentioned above.
Selecting the right solution for your system
It is vital that every gas processing plant selects the heat transfer fluid they use carefully, making an informed decision. Always examine original equipment manufacturers’ recommendations before ordering heat transfer fluids and using them. Using the incorrect product for a process can result in poor performance and, in worst-case scenarios, expensive system downtime, equipment repairs and replacement.
