PTQ Q4 2026 Issue

Sensitivity analysis

Efficiency recovery

$10/MWh

$20/MWh

$30/MWh

$40/MWh

$50/MWh

1.0% 1.5% 2.0% 2.5%

$0.23m $0.35m $0.47m $0.58m

$0.47m $0.70m $0.93m $1.17m

$0.70m $1.05m $1.40m $1.75m

$0.93m $1.40m $1.87m $2.33m

$1.17m $1.75m $2.33m $2.92m

Table 1 Sensitivity analysis showing estimated annual fuel cost associated with convection section fouling across different fuel price and efficiency loss scenarios. Figures are illustrative and based on six steam cracker furnaces operating 324 days per year1

furnace has a fired duty of approximately 50 MW, a 2.0% efficiency loss equates to around 1 MW of additional fuel demand per furnace. At a fuel cost of $40/MWh, this repre - sents approximately $311,000 per furnace per year. Across six furnaces, the annual fuel cost associated with this level of efficiency loss is approximately $1.87 million. Over three years, the cumulative saving from recovering this lost efficiency is estimated at approximately $5.61 million. The cost of fouling is also subject to external factors. The same level of thermal efficiency loss can have a very dif - ferent financial impact depending on fuel price, production value, plant utilisation, and market conditions. Again, fuel price is one of the clearest variables to give as an example. If reduced heat recovery forces an ethylene fur - nace to use additional fuel to maintain operating conditions, every MWh of avoidable fuel use becomes more expensive as fuel prices rise. Table 1 illustrates how estimated annual fuel costs change across different fuel price and efficiency loss scenarios. Operators may not be able to control regional feed - stock advantages, ethylene pricing or fuel price volatility. However, they can identify where avoidable efficiency losses are increasing their cost base. Fouling-related fuel loss is therefore part of a wider margin conversation, par - ticularly for assets under pressure to remain competitive. As a result, the commercial case for cleaning can strengthen even when the underlying technical issue remains unchanged. Realising that value, however, depends on cleaning access, coverage, and the ability to verify recovered performance. Limits of conventional cleaning Convection section cleaning can be difficult because of the asset geometry. Horizontal convection banks may contain multiple tube rows, with fouling accumulating between Remotely operated robotic clean - ing systems provide a controlled method for removing fouling from convection section surfaces that are difficult to reach using manual or line-of-sight methods

square or triangular pitch tube arrangements. Deposits can sit deep within the bank, beyond areas that are easily reached by manual or line-of-sight cleaning. Traditional cleaning methods can be effective in specific circumstances, but each has limitations. Manual hydro - blasting may provide inconsistent contact and require high volumes of water. Chemical and cryogenic methods may be constrained by access, handling requirements, offline time, or cleaning verification. If the fouling type is unknown, chemicals can compound the issue. Abrasive methods may not be suitable where there is concern over tube, insulation, or refractory damage. The relevant measure is not only whether some deposit has been removed, but whether enough heat transfer sur - face has been restored to recover useful duty and justify the intervention. This places greater importance on access, cleaning coverage, and performance verification. Robotic convection section cleaning Remotely operated robotic cleaning systems provide a controlled method for removing fouling from convection section surfaces that are difficult to reach using manual or line-of-sight methods. Providing access between finned tube rows, robotic systems can restore a high proportion of the original heat transfer surface area. This can improve recovered duty, reduce stack temperature, and support better steam gen - eration or superheat performance. The method can also allow cleaning to be carried out with greater control around tubes and refractory, helping to reduce the risk of damage during the cleaning process. Robotic systems typically offer several technical advantages: • Extended access: Articulated equipment can navigate between tube banks and reach convection section surfaces that may be difficult to clean using conventional methods. • Controlled cleaning: Computer-controlled cleaning arms can adjust level and angle to maintain more consistent con - tact with fouled surfaces. • Visual monitoring: Onboard cameras can provide opera - tors with real-time visibility during the cleaning operation. • Performance verification: Before-and-after imaging, combined with operating data, can be used to assess deposit removal, heat transfer recovery, and restored con - vection section duty. In operational terms, robotic cleaning can reduce the need for personnel entry into confined spaces and limit reliance on chemicals, abrasives or high volumes of water.

PTQ Q4 2026