Turning Up The Heat With A Hot Topic

Online Editor

Dennis Long explains how electric heaters can help meet decarbonisation goals

Pressure from industry leaders and legislation changes are encouraging the widespread need to shift fossil fuel use to renewables. One way many industrial manufacturers can embrace this is by shifting process heater systems from fuel-burning to electric. However, the transition is not as simple as throwing a switch. So how can manufacturers make the change from fuel-burning to electric?

Finally, the tides are turning when it comes to process heating. Pressures to electrify all industrial processes are increasing and electric heaters can offer an effective, environmentally friendlier solution.

According to the Environmental Protection Agency (EPA), a substantial portion of global greenhouse gas emissions come from industrial sources burning fossil fuels. Much of this energy is burned on-site for energy and heating needs. The US Energy Information Administration (EIA) estimates that the industrial sector uses approximately 24 quadrillion British Thermal Units (BTUs) of heat per year – roughly one third of the nation’s delivered energy supply. Process heating applications alone account for 36% of total delivered energy consumption within the manufacturing sector.

As a result, the pressures to decarbonise and electrify wherever possible are increasing. Companies industry-wide are quickening decarbonisation of their operations. In fact, a recent survey by Watlow found that over 90% of respondents in the oil and gas industry have developed, or are in the process of developing, a long-term strategy to reach sustainable, low-carbon site statuses.

Electrifying Processes

Electrification of process heating is one of the key strategies for addressing climate change concerns in oil and gas. Electric heaters do not burn fossil fuels and can be powered via renewable energy sources. Electric heat exchangers are no stranger to oil and gas operations, but historically, they have been used only in applications with a nameplate under 1 megawatt (MW). For example, in glycol reboiler heaters, knock-out drum heaters and fuel gas heaters and preheaters, gas-fired process heaters are still used in several ways, since the BTUs’ requirements for some of these processes can only be met by electric heaters with a much higher wattage.

However, there is growing potential to use electric heaters for applications requiring more than 1MW but less than 15MW. These span several areas, such as renewable fuel production. This is because hydrocarbon biofuels that are chemically identical to petroleum gasoline or diesel are produced from biomass sources through various biological, thermal and chemical processes. Electric heaters can also be used in carbon recycling, because methanol created from CO2 can be captured from industrial exhaust combined with hydrogen, either collected from industrial waste gas or, alternatively, from water through electrolysis.

Besides reducing the use of fossil fuels, electric heaters and heat exchangers have other advantages including less thermal lag, safer operation, more uniform distribution of heat and smaller overall footprint.

Electric Versus Fuel

One of the biggest developments in the area of electrification for process heating is in reliable, medium-voltage process heating systems. Solutions being developed by Watlow can tap directly into medium-voltage lines of up to 7,200V, reducing the need for large step-down transformers, circuits and cabling, which can considerably reduce installation, operation and maintenance costs.

What matters most in achieving process heating parameters is not the method of heating, but the heat flux of the heating surface. When it comes to these kinds of applications, electric heaters can safely achieve operating temperatures comparable to gas-fired heaters and with better uniformity and control.

Watlow recently introduced its Powersafe integrated, medium-voltage control and heating solution – a safe, reliable and clean replacement for fossil fuel alternatives in process equipment.

The new system integrates an electric heat exchanger, process controller and power system, as well as an isolated low-voltage enclosure including a human machine interface (HMI) and programable logic controller (PLC). It also incorporates a flexible combination of a silicon-controlled rectifier (SCR) and contactor circuits up to 20MW, delivering high-efficiency power greater than 99%, which reduces the overall size and weight of the solution.

Furthermore, wattage size requirements for electric thermal equipment are increasing, which makes medium-voltage solutions attractive because they reduce the overall installation costs of unnecessary cables and transformers. Watlow’s medium-voltage solutions also offer additional safety benefits such as a high-speed protective relay and breaker for rapid shutdown to protect personnel and equipment and safety interlocks for protection during operation.

Watlow is contributing to the decarbonisation needs of many industries that, historically, have had the greatest challenges in controlling emissions. A medium-voltage solution such as Powersafe helps to make the transition from fuel to electric as seamless as possible. 

Dennis Long is chief system designer at Watlow