‘Given the rapid pace of change, institutions must invest in training to keep teams current with emerging technologies,’ says Professor Omar Matar, Head of the Imperial College London chemical engineering department. ‘Hands-on technology is critical for engineering students. Long-standing partnerships illustrate the benefits of this approach. While the classroom is good for understanding the theory, direct use allows people to do it in practice.’

The Professor was speaking beside the University’s fully-functioning 50 kg/h Pilot Carbon Capture Plant, which for the past 15 years has put through their paces thousands of chemical engineering undergraduate and postgraduate students, plus visiting scholars to its South Kensington campus.

Since its launch, those ranks of students have read live data off 250 gauges and tweaked parameters on the 800 XA digital control system supplied by the facility’s industrial partner ABB. But Matar was also referring to artificial intelligence (AI), as his remarks were made on the occasion of an ABB press launch at the facility of instrumentation that incorporate some (limited) AI functions (see Box).

The 12-metre-high plant consists of twin gas columns arranged in a closed-loop figure-of-eight circuit. It can provide CO₂ gas streams at concentrations ranging from 6–30% by volume, to simulate post-combustion gases of both natural-gas fired power and coal-fired power, respectively. CO₂ and nitrogen gas are saturated with water and injected into the bottom of the left-hand absorber column, controlled to about 40°C. As the gas rises, it meets droplets of aqueous monoethanolamine (MEA) solution dripping from above in a counter-flow arrangement. (The circuit is charged with some 200 litres.) The carbon-rich liquid is pumped to the top of the right-hand regenerator column, where it flows by convection into the re-boiler, where its temperature is raised to 115°C. There, the liquid turns to vapour and moves into the condenser, where the amine solution condenses, leaving purified gas-phase CO₂. The amine solution returns to the regenerator to be further recycled. (Unlike real carbon capture and storage plants, this one recycles the CO₂, rather than sending it on for compression or liquefaction.)

While obviously of great interest to students planning to work in energy transition technologies, the plant was specifically chosen to offer a much wider audience, explains Senior Teaching Fellow Colin Hale, who runs the plant with help from department technicians and PhD students. First, the plant uses a refining process nearly a century old – the gas sweetening process – so named because it reduces smelly hydrogen sulphides (H₂S), as well as CO₂. In addition, the inclusion of standard components and common inspection and maintenance tasks makes it representative of many chemical engineering plants.

But with a crucial difference. Although Hale states that the plant operates in some fashion most days, it is not bound by the demanding uptime requirements of an actual production plant – which minimises the consequences should students make an operational mistake. Second, although rated to run at pressures up to 10 bar, the facility is usually run at around atmospheric pressure, to minimise the health and safety risks that high-pressure leaks might pose to students and the building which surrounds it with laboratories, classrooms and offices.

A view down the length of the Pilot Carbon Capture Plant at Imperial College, London  
Photo: W Dalrymple

Over 400 students a year, including the entire chemical engineering roster, come to work in the facility. First year undergraduates grapple with process and instrumentation diagrams in the control room, as well as managing practical matters such as permits-to-work. First-years are also sent off to find components of particular importance, such as the heat exchangers mounted in the middle of the columns.

Second-year and visiting students over the summer are given the major task of ‘walking the line’, comparing P&IDs (piping and instrumentation diagrams) to physical reality, and identifying every major component. To enhance the plant’s ability to replicate an authentic industrial experience, the plant is over-instrumented. There are both analogue and 4-20 mA digital gauges measuring temperature, pressure and flow. They use a variety of communication methods: RS485 (Fieldbus), Profibus BA, Profibus DA and wireless Hart 7 transmitters. A development project will see an industrial ethernet added. A further task for the students is to locate the few instruments installed in incorrect positions.

Another second-year assignment covers shift changeover communication and prepares students to think about the risks of poor information exchange, which has been found to be the root cause of several industrial accidents. Third-year students work on control loops and aim to ‘tune’ the system to improve operation and efficiency.

Graduate students perform more advanced research, looking to optimise the process through gathered performance data. One project, for example, aims to supplement data gathered by the gas analyser. It can measure gas concentrations directly at multiple column heights (a vital aspect of process control). But switching between different points takes a short period of time, leaving gaps in the data. In collaboration with ABB, students developed an inferential modelling platform – so-called ‘soft sensing’ to estimate the column parameters based on readouts from other parts of the process.

According to Hale, the principal changes to the Pilot Carbon Capture Plant since launch have been either in sensing, or in developing ways to use the data generated to improve the process. For example, by reducing the amount of energy consumed, or detecting anomalies before they upset the process.

As to the former, ABB has used the site as a test bed for new products, including an energy-harvesting sensor powered only by a stable temperature difference between the process pipework and ambient, which trickle-charges its battery. ABB also trialled a NINVA (non-invasive temperature probe) that, being surface-mounted, doesn’t disturb the flow and avoids introducing a leak path into the system.

ABB Measurement & Analytics Global Digital Lead David Lincoln describes the relationship between the college and ABB as ‘particularly strong’. Having donated equipment worth £1mn when the facility was first built in 2012, it has continued an ongoing strategic partnership. From ABB’s point of view, the plant serves a number of different purposes, from introducing potential future customers to ABB products to providing a pool of possible recruits.

Imperial College is ABB’s only UK academic partner, although it does have others elsewhere in Europe. ABB also carries out industrial R&D in the UK, at its facilities in Stonehouse, Gloucestershire (for water analysis and flow measurement) and in St Neots, Cambridgshire (water recorders and controllers).

Lincoln adds: ‘We don’t see many plants like this, connected to the cloud, where we can share KPIs (key performance indicators) remotely.’ In 2018, ABB worked with Imperial College to independently connect to device data through the control system network, to transfer diagnostics data to the edge computer and to the cloud. That was ‘the world’s first cloud-hosted verification system’, the company claims.

As significant as it may be, the Pilot Carbon Capture Plant is not the only aspect of energy transition focus at the elite, engineering-focused university. Imperial College’s centre for carbon capture and storage (CCS) contributes to the UK CCS Research Centre, hosts the industry-funded Qatar Carbonates and Carbon Storage Research Centre, investigates CCS through its Sustainable Gas Institute and explores the bioenergy angle in the Clean Fossil and Bioenergy Research Group. Other current research includes a calcium looping process to capture CO₂ in cement production for concrete (a hard-to-abate sector), and multi-scale modelling of networks. Also housed at Imperial College London is the Grantham Institute, a hub for climate and environmental research.

ABB My Measurement Assistant+ demonstrating a Visual Remote Support call from the tech support side
Photo: W Dalrymple

• Further reading: ‘On the horizon: Norwegian CCUS vision soon to be made real’. Despite cost overruns, Norway’s Northern Lights carbon capture, use and storage project is heading towards start-up in 2025, with a first-phase capacity of 1.5mn t/y, rising to 5mn t/y in the second phase. That schedule puts the scheme in the running to be among Europe’s first large-scale CCUS projects to start up. 
• Carbon capture and storage looks set to take-off after decades of research. Francesco Finotti of SINTEF Energy Research examines the latest technological initiatives and developing value chain.