Effective moisture control in oil and gas prevents corrosion, ensures product quality, and boosts efficiency, with accurate measurement achieved through advanced analyser design and proper sample system management, Ryan Cumpston, AMETEK Process Instruments, tells OGN

In the oil and gas industry, effective moisture control is vital for preventing corrosion, maintaining product quality, enhancing safety, and optimising operational efficiency.

The presence of moisture, especially when combined with impurities, can accelerate corrosion in pipelines, storage tanks, and processing equipment. This can lead to leaks, equipment failures, and increased maintenance costs.

Moisture can also affect the efficiency of the refining processes.

For example, in catalytic cracking and other refining processes, moisture presence can impact catalyst effectiveness and adversely impact the overall yield of refined products.

Fluctuations in moisture levels may also cause products to fall out of specification, affecting marketability and regulatory compliance.

Despite its critical importance, monitoring moisture levels in processes can be a complex and challenging task.

UNDERSTANDING MOISTURE BEHAVIOUR

Moisture behaves uniquely due to the polarity of water molecules, which causes water to adhere to itself and to surfaces.

The AMETEK 3050 moisture analyser ensures accurate measurements in challenging conditions

Additionally, water’s high heat capacity allows it to absorb substantial heat before its temperature rises.

When water absorbs heat, water molecules disassociate and are able to move more freely, a key factor in understanding moisture behavior as temperatures change.

The diurnal effect, or the rise and fall of temperatures between day and night, is particularly pronounced in regions like the Middle East, where these daily temperature variations can exceed 15 deg C.

Typically, with cooler nighttime temperatures, less energy in the form of heat is available to cause water molecules to move.

Thus, at night, the diurnal effect results in lower moisture concentrations due to moisture molecules adhering to tubing walls and other system components.

As the system and gas warm during the day, the moisture gains energy and is released from these surfaces, leading to higher moisture content readings.

In applications, such as refineries and natural gas processing, understanding, and managing these temperature-driven fluctuations is crucial, as daily, or even seasonal (winter-to-summer) changes significantly impact dehydration and custody transfer processes.

Since these diurnal moisture variations influence the overall processes, operators should take measures to prevent or mitigate these effects.

EFFECTIVE SAMPLE SYSTEM DESIGN

However, it is critical that the preventative measures do not compromise the moisture analyser’s ability to monitor accurately the moisture content in the process gas.

For over 50 years, AMETEK Process Instruments has been a global leader in process moisture measurement.

To mitigate the impact of ambient temperature variations, AMETEK’s quartz crystal microbalance (QCM) moisture analysers incorporate a heated oven, ensuring measuring cells remain at 60 deg C.

As a result, analysers such as the AMETEK 3050-OLV offer accurate and reliable moisture analysis from percentage levels down to sub-parts-per-million (sub-ppm) concentrations, even in varying temperature environments.

OPTIMISING MEASUREMENT ACCURACY

But the moisture analyser is only one part of the overall measurement system. To ensure reliable moisture measurements around the clock, operators must implement proper sample system design principles as well.

The accuracy of moisture content measurement depends on the effective extraction, transport, conditioning, and delivery of sample gas to the analyser. Some key strategies in this regard include:

• Minimising sample volume and surface area: Positioning pressure reduction regulators as close as possible to the tap minimises the length of sample tubing between the process takeoff location and the analyser. This reduces the available surface area where moisture molecules can adsorb, enhancing the speed of response and improving overall accuracy. Using electropolished tubing provides the additional benefit of smoother internal surfaces, reducing sites on the tubing walls where water molecules can adhere.

• Maintaining high sample flow: Ensuring high sample flow through the conditioning system allows the analyser to receive fresh samples quickly. A bypass or speed loop can assist with increasing the sample flow while allowing a lower flowrate through the analyser if required.

• Eliminating dead legs: Dead legs, areas in the sample system without continuous gas flow, can trap moisture. By minimising unnecessary gauges, tees, and other components that create dead legs, the risk of moisture release is significantly lowered, reducing potential errors and ensuring more accurate moisture readings.

• Temperature control: Shielding moisture analysers from direct sunlight will prevent overheating and damage to the analyser. Additionally, utilising heated sample lines and regulators maintains sample system temperature reducing the diurnal effect on the sample tubing and sample system.

By implementing these techniques, operators can guard against diurnal effect challenges and be confident that their moisture measurements remain precise.

AMETEK Process Instruments utilises its decades of experience to provide sample systems specifically designed to ensure maximum accuracy, regardless of environmental conditions.

CONCLUSION

Effective moisture management in refineries and natural gas processing is crucial for preventing corrosion, preserving product quality, and optimising operational efficiency.

Accurate moisture measurement enables operators to understand process conditions thoroughly and apply strategies that ensure sustained performance.

To achieve reliable moisture readings around the clock, operators should follow sound sample system design principles.

By minimising sample volume, maintaining high sample flow, eliminating dead legs, and controlling temperature, they can effectively counteract diurnal variations and achieve precise measurements.

Find out more: www.ametekpi.com/moisture