Reducing operational costs, capital expenditures, and carbon emissions is increasingly critical for industrial plants. At Axens’ 2025 Low Carbon Solutions Seminar, Rémi Duval, Senior Furnaces Process Engineer, and Jan Reneteau, Managing Director of Nectis (a joint venture between Axens and ZPJE), introduced two innovative heating technologies: the electric tubular heater and the high-efficiency spiral tube heat exchanger. These solutions aim to enhance sustainability and efficiency in refinery and petrochemical operations.
Axens’ clients are targeting a 30% reduction in Scope 1 and 2 emissions and a 20% reduction in Scope 3 emissions by 2030, compared to 2019. Traditional fired heaters, powered by natural gas or refined fuel gas, have long been central to refinery operations but are major contributors to CO₂, NOₓ, SOₓ, and CO emissions. Many of these systems are outdated and inefficient, prompting the need for cleaner alternatives.
Electric tubular heaters offer a retrofit solution that replaces fuel burners with electric heating elements, while keeping the process-side components unchanged. This simplifies implementation and eliminates CO₂ and other pollutants when powered by green renewable electricity. These e-heaters also provide enhanced reliability, with heating elements designed to last 20+ years.
Controlled via thyristors, the e-heaters offer precise heat flux management, avoiding flame impingement and tube overheating. Safety is improved with contactors replacing traditional valves, and remote start-up capabilities reduce operational risks. Maintenance is minimal due to the absence of rotating parts, while process tubes are protected from overheating. Axens has deployed low-duty heaters (<1MW) and is now scaling up to high-capacity models exceeding 20+ MW units, with active projects in South Africa, Germany, and Asia. These electrical furnaces are ideal for refineries seeking scalable, low-emission alternatives to fired heaters.
The spiral tube heat exchanger is a high-efficiency alternative to conventional shell-and-tube designs. Its unique structure—coiled tubes around a central pipe within a shell—creates a true countercurrent flow, maximizing thermal efficiency. These exchangers can achieve hot approach temperatures as low as 3–4°C, enabling optimal energy recovery.
With up to 30,000 m² of heat transfer surface in a compact design, they save space and reduce maintenance needs. Visual inspections are standard, and defective tubes can be plugged like in traditional systems.
Over 500 units are already in operation in refining and petrochemical sites, primarily in China, with applications ranging from LPG, naphtha to diesel and vacuum gas oil. The first unit in a hydrocracking unit, installed 18 years ago, is still operational. Axens has deployed 24 units in licensed diesel hydrotreating and hydrocracking operations, and 12 in reforming and aromatics units. These exchangers are also used in crude distillation and petrochemical processes.
In a case study, a diesel hydrotreater unit was retrofitted to increase capacity and reduce CO₂ emissions. The original fired heater was at full capacity, and the existing exchangers were insufficient. One option involved replacing existing 7 shell and tube heat exchangers with 3 spiral exchangers that would recover all available heat enabling the unit to operate without the fired heater during normal operation. While this eliminated CO₂ emissions, it introduced water into the diesel, complicating downstream processing.
A second option retained the existing stripper reboiler and added 2 spiral tube exchangers to reduce heater duty by 70%. A smaller electric heater was installed to meet the remaining heat demand, maintaining zero CO₂ emissions during normal operation.
This solution saved four exchangers and significantly reduced fuel consumption. CO₂ emissions dropped by 25,000 tons per year, translating to €2.5 million in annual savings at a carbon price of €100/ton.
Electric tubular heaters and spiral tube heat exchangers represent a new era in industrial heating. They offer improved efficiency, reduced emissions, and long-term reliability. These technologies are scalable and align with global sustainability goals, making them ideal for refineries and petrochemical plants seeking to modernize operations.
