Meeting International Environmental and Quality Standards With Electrode Boilers

High-voltage electrode boilers could replace gas or oil-fired boilers to reduce emissions

Published: Monday, October 25, 2021 - 12:03

The pressure for industry to reduce harmful emissions and greenhouse gas emissions in particular has increased significantly in the past few years. Recently, President Joe Biden set an aggressive new target for the United States to reduce net greenhouse gas emissions by 50 to 52 percent from 2005 levels by 2030. The announcement, made at the Leaders Summit on Climate held in April 2021, challenges global leaders to raise their ambitions to tackle climate change on the scale required.

In December 2020, the European Union agreed to cut greenhouse gas carbon emissions by 55 percent by 2030 compared to 1990 levels. According to a recent report that has tracked the EU’s power sector since 2015, renewables surpassed fossil fuels last year (38% to 37%), indicating that industry is already pivoting away from carbon emissions.

Boilers could be low-hanging fruit

In order to meet these requirements, companies are looking for ways to reduce emissions. Some look to renewable energy, others toward process or production changes, or even changes in their supply chain. But often, the fastest most cost-efficient action is to update outdated equipment. In a previous article, “What Are the Benefits of a Low-NOx Boiler?” Quality Digest author Emily Newton wrote about the need to reduce nitrogen oxide (NOx) emissions in industrial boilers. The EPA’s Clean Air Act regulates NOx emissions in the United States, and the agency’s “Primary National Ambient Air Quality Standards” (NAAQS) for nitrogen dioxides determine how much NOx a facility can produce in a certain amount of time. Addressing NOx emissions has the affect of killing three birds with one stone: satisfy the EPA, address national GHG emissions targets, and lower operational costs.

Depending on the industry, boilers can be a significant part of a company’s emissions, and in some cases its energy usage. With gas or oil-fired boilers, there are several ways to reduce NOx emissions, including, as Newton pointed out, more efficient fuel combustion, which incidentally also reduces fuel costs.

But boilers that burn fossil fuel aren’t the only option. Before looking at retrofitting or replacing your gas or oil-fired boiler for energy efficiency, it might be worth looking at high-voltage electrode boilers. Electrode boilers have been around for decades but are getting some renewed interest. Popular in Europe during the 1960s, electrode boilers were used mostly as a means of thermal storage for electrical-power generation. They were typically used in areas where hydro power was plentiful, such as Switzerland. However, they never really caught on in other contexts, in part because their output couldn’t rival gas and oil-fired boilers when those were an option. Today, advances in the technology mean that electrode-boiler output is close to that of its fossil-fuel counterparts in many applications.

For process industries electrode boilers offer several advantages over oil and gas. Not only do they help reduce emissions, they also help address lean manufacturing goals such as more efficient use of space, less waste, higher efficiency, better safety, less maintenance, and faster and more precise temperature control.

For more information on high-voltage electrode boilers, we interviewed Robert Presser, vice president of Acme Engineering, a North American manufacturer of boilers for large industrial and commercial applications. The company is an ISO 9001:2015-certified manufacturer of environmental controls and systems with integrated mechanical, electrical, and electronic capabilities.

Quality Digest: For executives focused on quality, what is the argument against traditional gas and oil-fired boilers?

Robert Presser: In industrial processing, besides the notorious greenhouse gases carbon dioxide (CO₂) and methane (CH₄), natural gas-fired boilers and furnaces emit dangerous nitrogen oxides (NOx), carbon monoxide (CO), and nitrous oxide (N₂O), as well as volatile organic compounds (VOCs), sulfur dioxide (SO₂), and particulate matter. These emissions are hazardous to employee health and environmental safety.

QD: How do electrode boilers function?

RP: Electrode boilers utilize the conductive and resistive properties of water to carry electric current and generate steam or heat hot water. An AC current flows from an electrode of one phase to ground using the water as a conductor. Since chemicals in the water provide conductivity, the current flow generates heat directly in the water itself. The more current (amps) that flows, the more heat (BTUs) is generated, and the more steam or hot water produced.

As an example, the electrodes of the CEJS High-Voltage Electrode Steam Boiler by Acme, a Canada-based manufacturer of industrial and commercial boilers, are vertically mounted around the inside of the pressure vessel. This enables the unit to produce maximum amounts of steam in a minimum amount of floor space, with boiler capacity from 6 MW to 52 MW.

The boiler operates at existing distribution voltages, 4.16 to 25 KV with up to 99.9-percent efficiency, and can produce up to 170,000 pounds of steam per hour. With pressure ratings from 105 psig to 500 psig, the boilers are designed to ASME Section 1, and are certified, registered pressure vessels at the location of the boiler.

QD: What is the argument for modern electrode boilers?

RP: With zero emissions, economical electric steam and hot water boilers deliver maximum thermal output in a minimum spatial footprint. Crucially, almost 100 percent of the electrical energy is converted into heat with no stack or heat transfer losses.

This is, in part, due to technological advances in electrode boiler design that increase the kilowatt output to a level that rivals even large gas or oil-fired boilers. When process heating is used to raise process steam or hot water temperature, electric-powered alternatives are sure to be a critical piece of the puzzle in meeting future emission reduction goals.

QD: What, if anything, has held back the adoption of modern electrode boilers?

RP: There is an entire generation of industrial process engineers that grew up with oil and gas-fired boilers almost exclusively. As a result of preconceived notions, most view electrode boilers as small underpowered units, like a hot water heater. So, we frequently have to educate engineers that there is electrode-boiler technology that can match the capacity of large gas or oil-fired boilers available.

QD: What are the advantages of modern electrode boilers over traditional options in terms of quality, safety, and reliability?

RP: High-capacity electrode boilers are well suited to heat process water or to produce steam. Electrode boilers have several advantages compared to oil or gas-fired boilers, including superior safety, ease of installation, faster start-up and shut-down time, and quiet operation. Electrode boilers can have a nearly 100-percent turndown, unlike gas-fired boilers that often have a 30-percent low-fire or have to pulse their burners, which leads to inefficient operation.

Electrode boilers do not need an operator. If anything goes wrong, the breaker trips, preventing further escalation of the issue. There are no combustion hazards because there are no flames, fumes, fuel lines, or storage tanks. With gas-burning boilers, any gas leak can increase the risk of an explosion. So, gas units must usually be continually monitored or periodically inspected. State and municipal safety guidelines vary depending on boiler type and the expected frequency of inspection. In addition, there is no low-water danger since the current cannot flow without water. There are also no problems with head buildup or electrode burnout even if scaling should occur. Thermal shock is eliminated.

Electrode boilers have a minimum number of components and electrical controls. With fewer parts and no fuel residues, cleaning and maintenance requirements are reduced. Simple control systems provide maximum reliability. The absence of excessive temperatures and burnout ensures long operating life.

With electrode boilers, the energy input as well as output adjustment is precise and almost immediate. In contrast, increasing or decreasing the temperature in a gas-fired boiler is a slower process because it takes time for the heat in the boiler to rise or dissipate before reaching the targeted output.

The electric units are exceptionally quiet compared to fuel-fired boilers. Unlike gas-powered burners that throttle like turbine engines almost continually, electrode boilers keep operational noise levels down. Because the loudest boiler component is a circulating pump motor, it is easy to have a conversation next to one without having to raise your voice.

QD: What else should executives consider when it comes to industrial process heating?

RP: Industrial plants that depend on process heating will need to consider alternatives like modern electrode boilers that not only improve quality and safety but also satisfy international standards and environmental agreements. The sooner this is considered, the greater the competitive advantage in the marketplace.

For more info, contact Robert Presser at Acme Engineering via email at rpresser@acmeprod.com or call (888) 880-5323.

About The Author

Dirk Dusharme @ Quality Digest

Dirk Dusharme is Quality Digest’s editor in chief.