Decarbonisation Technology - November 2021

Monitoring technology for ethylene crackers and SMRs

Digital solutions and infrared technologies help steamcracker and SMR operators improve temperature homogeneity and fuel efficiency

James Cross AMETEK Land

B old strategies to reduce carbon emissions are being released with growing regularity, often with aggressive targets and recommendations. For example, in August 2021, the UK government released a low carbon hydrogen strategy, built around blue and green hydrogen, to meet what it terms legally binding commitments to net-zero emissions. The US government is now proposing a 52% reduction in US greenhouse gas emissions from 2005 levels by 2030, far sooner than previous pledges. The new economic and technical regulatory environment means that refineries and petrochemical industries must radically change in the long term and make significant improvements in efficiency in the short term. A sensible place to start is with the optimisation of their most carbon-intensive fired heater processes. Two of the largest and most carbon-intensive refinery and petrochemical fired heaters are steam methane reformers (SMR), which largely supply hydrogen to refineries for ammonia/ methanol production, and steam crackers for ethylene production. Steam methane reformers emit around 800 million tonnes of carbon dioxide (CO 2 ) per year, and steam crackers are estimated to produce 260 million tonnes of CO 2 emissions per year. 1 Whilst much is written around the potential to reduce CO 2 emissions from these fired heaters by upgrading burners, changing tube/coil/refractory materials, and improving combustion efficiency, little attention is paid to the importance of temperature monitoring and control and the role it can play in improving process efficiency.

Steam methane reforming and blue hydrogen production Over 95% of the world’s hydrogen is produced using steam methane reforming, generally utilising desulphurised natural gas, refinery off- gas, liquefied petroleum gas (LPG), or naphtha as a feedstock. The feed is preheated and mixed with steam before entering the primary reformer, where the mixtures pass over a catalyst to produce hydrogen, carbon monoxide (CO) and CO 2 . CO is shifted with steam to additional hydrogen and CO 2 , before pressure swing adsorption (PSA) is used to separate hydrogen. Without carbon capture, usage and storage (CCUS), this is known as grey hydrogen, but when CCUS is used blue hydrogen is produced.

Figure 1: Thermal image of a side-fired SMR produced using the AMETEK Land NIR-B-640-EX Fixed The Imaging Borescope. Each pixel represents a temperature value. Figure 1 Thermal image of a side-fired SMR produced using the AMETEK Land NIR-B-640- EX fixed thermal imaging borescope. Each pixel represents a temperature value Autothermal Reformers (ATR) can also produce blue hydrogen when used together with CCUS, and technology licensors claim conversion efficiencies of 84% (HHV) with CO 2 capture rates of 95%. The natu gas feed is combusted to produce heat for the reforming reaction, so no separate fuel source is needed, with SMRs. This process means ATRs can achieve higher conversion efficiencies and CO 2 capture rates th SMRs as there is only a single CO 2 stream. In the new, highly competitive landscape where efficiency and capture are critical to a plant's profitability, SMR operators must improve their efficiency to stay competitive. (2) 77