Moisture Measurement and Carbon Capture

Preventing corrosion and compressor damage in CCUS

Time is running out. If we’re to meet the critical climate targets set out by many national and international institutions, especially the goal of reaching global net-zero by 2050, then we need to take decisive action now.  But acting rapidly is only part of the challenge.

Slowing and reversing the rate of climate change is a complex process, both scientifically and politically.  Success requires cooperation between disparate and often conflicting regimes, political groups, societies and cultures.  It also depends on cohesive environmental strategies that tackle every aspect of global warming in detail and over a sustained period. 

It’s widely acknowledged that a major part of the problem is the emission of greenhouse gases – carbon dioxide (CO₂), methane, nitrous dioxide and fluorinated gases – which has increased dramatically since the industrial revolution. 

Although significant steps have been taken in recent decades to reduce emissions, the rate at which we’re generating C0₂ continues to rise inexorably; and at 80 % of the total emissions it’s by far the greatest contributor to the problem. 

Experts have, rightly, suggested that if we’re struggling to reverse the rise in CO₂ emissions then we have to find other solutions.  Hence, the rapid growth in Carbon Capture, Usage and Storage (CCUS). 

The CCUS market is growing at around 14 % per year and is set to reach a projected value of at least $7 billion by 2030, according to analysts Allied Market Research.  These figures are supported by the IEA (Independent Energy Authority), which reports that in 2021 alone over 100 new CCUS facilities were announced.  This represents a doubling over the previous year. 

Growth is being driven by high levels of investment from governments and industry – over $25 million in around 12 months – plus the advent of new removal, capture and sequestration technologies, and a greater ability to convert waste CO₂ into commercially viable products. 

Carbon Capture and Storage

The majority of Carbon Capture and Storage schemes use depleted underground gas reservoirs.  CO₂ is captured at source, typically a power station or large industrial process site, and then piped under pressure to a central compressor station.  Here, the pressure is further increased, before the gas is pumped into an empty gas field, normally using existing pipeline infrastructure. 

In the Netherlands, for example, the Porthos project will pump pressurized gas from an onshore compressor station along a 22-km pipeline to a redundant offshore gas platform.  The CO₂ will then be stored in a depleted gas field in an area of sealed porous sandstone that lies 3 km below the North Sea.  The plan is to capture approximately 2.5 Mton of CO₂ each year until the field reaches its capacity of 37.0 Mton, at which point it will be sealed permanently. 

The Porthos project is one of many that are either in development or planned in the next few years.  Each represents a significant investment, with a high value infrastructure, especially the network of pipelines and compressor stations.  Clearly, it is critical that these systems operate efficiently and reliably for the life of each project. 

Moisture measurement is key to preventing corrosion

Moisture entrained in the CO₂ can be a considerable problem, causing corrosion in steel pipelines with the potential for leaks of gas to atmosphere, and damage to the compressors used to pressurise the gas for transportation and storage. There is also the risk that a reaction between water vapor and CO₂ will result in the formation of carbonic acid (H2CO3), which can accelerate the rate of corrosion.  Additionally, if other trace gases are present, such as ammonia or hydrogen sulphide, they may combine with moisture to form aggressive acids. 

Drying or dehydration systems are used to reduce moisture levels.  This equipment is, however, energy intensive, so that moisture dew-point measurement becomes an important technique both to ensure that energy efficiency is optimized and pipelines are protected from corrosion. 

A further issue is the need to agree common principles for measuring impurities in CO₂.  As a report from the National Physical Laboratory states, ‘More accurate determination of dew-point and the establishment of more reliable thresholds for impurity levels in the CO₂ stream would help to de-risk the business case for investment and provide greater confidence in the safe use of pipelines for transport of dense phase CO₂’. 

Advanced dew-point measurement

A key step in developing a common approach is to use industry-standard instruments, which are capable of producing precise and consistent measurements of trace impurities in CO₂ gases, at both the compression and transportation stages. 

The latest Michell Instruments’ dew-point analyzers are designed to detect extremely low levels of condensing liquids, including both water and hydrocarbons.  For example, our QMA601 and QMA401 quartz crystal moisture analysers offer fast response to process moisture changes, with integrated automatic calibration functions that ensure optimal long-term accuracy.

These systems incorporate proven sensor technologies, are simple to set up and use, and are used as reference instruments by leading calibration laboratories around the world.  As such, they offer ideal solutions for all organizations involved in the rapidly expanding Carbon Capture and Storage sector. 

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Carbon dioxide measurement

The process of CCUS is able to capture up to 90 % of C0₂ emissions that are released by burning fossil fuels during electricity generation and industrial processes such as steel or cement production.

To collect the carbon dioxide, the plant uses fans to draw air into a collector, which has a filter material inside. Once the filter material is filled with CO₂, the collector is closed and the temperature is raised to release the CO₂ from the material, after which the highly concentrated gas can be collected. The CO₂ is then mixed with water and injected at a depth of 1,000 meters into the nearby basalt rock where it is mineralized. The CO₂/water mixture turns to stone in about two years, and hydride of sulphur (HS₂) within four months.

Understanding the effectiveness and efficiency of the carbon capture process is critical to the success of the overall process.

Nondispersive infrared sensors, designed and manufactured by Dynament, offer the most accurate and reliable technology for the measurement of carbon dioxide. The Dynament NDIR sensors are fail-safe, provide continuous measurement, and have a wide environmental range of operation to meet the needs of this challenging application. Dynament has met a standard of excellence over the past 20 years and offers specific carbon dioxide ranges from 0-2000 ppm CO₂ to 0-100 % CO₂.

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With almost 50 years' experience in the development of innovative precision instruments, we are the application experts in humidity measurements for all Carbon Capture and Storage applications. If you would like to discuss your requirements, then please contact our team today.

Sources

CCUS market – Allied Market Research

Greenhouse gases – US EPA

Number of CCUS facilities – IEA

National Physical Laboratory energy transition report: