Batteries have become a key contributor in the world’s energy transition and critical in the effort to slow climate change. As a result, battery manufacturing technologies and techniques are constantly evolving as producers look to remain competitive, increase storage capacity, and improve efficiency while decreasing battery size and weight. For instance, some producers are turning to a silicone-based anode material to increase battery output and reduce cost; others are exploring mining lithium from seawater to alleviate supply issues. When combined with an unprecedented increase in demand and subsequent production increases, it is fair to say that manufacturers are in a constant state of change. And it is not slowing down: some experts estimate the lithium-ion battery market alone will expand 18% by 2030. In short, we need more energy storage, in smaller batteries, at lower costs.
Lithium-ion batteries are considered the most energy-dense and longest-lasting rechargeable batteries currently available. The process of making them varies, but in general it consists of mixing raw materials followed by a series of coating, laminating, drying, cutting, winding, welding, sealing, forming, pre-charging, and degassing before a final test. However, when battery advancements occur, many of these existing production inputs and manufacturing practices need to change quickly. This can include raw material adjustments, production equipment modifications, or a change in coating techniques, just to name a few. The pollution control technologies employed at the battery manufacturing facilities are also affected by the upstream changes but are often an afterthought by plant personnel.
Regulated by most state and federal agencies, Volatile Organic Compounds, or VOCs, are pollutants generated in many manufacturing processes. The battery industry is accustomed to these harmful byproducts and the compliance hurdles that accompany them. The organic vapors are dangerous to humans when inhaled in quantities over an extended period. They also interrupt and destroy natural plant processes and play a significant role in the formation of ozone and smog. Hazardous Air Pollutants (HAPs) are a classification of VOCs with additional harmful properties, including potentially causing birth defects, nervous system damage, and even death in concentrated levels; HAPs are also a regulated pollutant from battery manufacturing.
One synthetic graphite anode powder manufacturer was modifying their furnaces to accommodate new products for lithium-ion battery manufacturing. Because their production facility was in a non-attainment area, per the United States Environmental Protection Agency (EPA), air quality standards required them to take special precautions. This meant a Title V permit would be required, as they have the potential to emit more than 100 tons per year (TPY) of VOCs, more than 10 TPY of any single HAP, or more than 25 TPY of any combination of HAPs.
This manufacturing plant in the United States produces high-performance anode material for lithium-ion batteries. A key component of lithium-ion batteries is the anode which stores and releases the lithium ions. Graphite is currently the most commonly used anode material. The process starts with a petroleum coke, which is formed into a synthetic graphite through graphitization. During operation, between 12 to 18 graphite furnaces, which are modular in construction and electrically heated utilizing local hydropower, are needed to meet the production demands.
This facility was no stranger to environmental stewardship. In years prior, they completed an Environmental Assessment to secure financial assistance from the Department of Energy and participate in the American Recovery and Reinvestment Act, which aims to accelerate the development and production of electric-drive vehicles systems to substantially reduce the United States’ consumption of petroleum. In fact, the site itself remains nearly 70% greenspace today.
In keeping with the company’s sustainability goals, they immediately began the search for an effective and efficient air pollution control system. As is the case with many manufacturing operations, process emissions are best destroyed using thermal and catalytic oxidation technologies where time, temperature, and turbulence convert VOCs and HAPs to heat, water vapor, and small amounts of carbon dioxide (CO2).
Widely considered the most energy-efficient oxidation technology, the Regenerative Thermal Oxidizer (RTO) uses these oxidation principles with a unique heat recovery component. Highly effective ceramic media within the oxidizer captures heat from emission combustion and reuses it to preheat incoming pollutants. The RTO also uses uniquely designed poppet valves to divert process air into and out of the oxidizer, properly balance emission loading, maintain destruction efficiency, and optimize heat recovery. Most RTOs are a two-bed design, but they can be designed in a multi-chamber configuration to accommodate larger airflows and achieve destruction efficiencies above 99.7%.
Given the emission loading and low process temperature, the company chose the RTO for its high destruction capability above 99%, and a preowned system was selected to meet their aggressive timeline for compliance. The refurbished, two-bed RTO from Anguil Environmental Systems was delivered, installed, and operational in less than ten weeks. It treats up to 5,000 standard cubic feet per minute (SCFM) of process flow containing methane, ethylene, acetylene, carbon monoxide (CO), benzene, aromatic hydrocarbons, and aliphatic organics from the electrically heated furnaces and corresponding collection hoods. Dilution air at each furnace was added to keep the overall lower explosive limit (LEL) in the duct system below 25%, per code.
The oxidizer can be operated in a bake-out mode to allow for the removal of organic build-up on the heat exchange media. At a reduced airflow, the outlet temperature is allowed to become elevated before the flow direction is switched, and this hot air vaporizes organic particulate that may have collected. Certain components of the RTO are insulated to prevent the temperature of the outer skin from increasing during bake-out.
Advanced programmable logic controls record vital oxidizer operating parameters for regulatory reporting and ethernet communications allow for remote diagnostics and service support. A variable frequency drive aids in minimizing operating cost by providing fan turn-down when only low airflow is required in the RTO.
Air pollution and greenhouse gas emissions from this facility remain extremely low due to the efficiency of the pollution control system and utilization of hydropower for the process furnaces. A preowned abatement system was selected to meet an aggressive timeline at this particular facility. However, battery manufacturers all over the world are employing various thermal oxidizer technologies to meet their unique process conditions. For instance, some silicone-based anode precursor manufacturers are utilizing direct-fired oxidizer technologies with downstream particulate control to handle silicon dioxide emissions and remain in compliance. Regardless of the process, oxidizer selection is application specific and should be based on emission constituents, process parameters, efficiency needs and regulatory requirements.
As individuals and corporations continue to push towards smaller carbon footprints, the use of Lithium-Ion Batteries (LIB) has become increasingly prevalent. Specifically for individuals, the utilization of battery packs for all-electric automobiles and solar-powered home battery banks have continued to grow at a rapid rate. The manufacturing of these battery packs generates several air pollutants that must be treated prior to being released to atmosphere.
One large supplier of LIBs faced a unique set of challenges at their main production facility.
- Three identical abatement systems were required, capable of handling up to 35,000 SCFM of emission laden air each. Electrically heated air pollution control systems are typically much smaller.
- Fossil fuels (natural gas, propane, fuel oil, diesel, etc.) of any kind are not allowed in the factory.
- Process gases consist of both ambient and hot air streams, both with very low concentrations.
- All abatement systems were to be installed indoors on the third floor of the factory with very tight footprint and height constraints.
Manufacturing of complete LIBs requires several different processes and operations that produce Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs) at varying temperatures. For instance, making battery electrodes uses N-Methyl Pyrrolidone (NMP) which is a solvent the manufacturer can recover and reuse without treatment in a pollution control device. However, this supplier had additional module manufacturing lines and multiple e-coat paint lines with curing ovens where solvent recovery was not an option. This further complicated the compliance solution.
Anguil was tasked with developing a compliance solution to capture and treat 70,000 SCFM of emission laden air with the following requirements:
- Achieve a minimum 90% overall air pollutant reduction
- Any heating requirements must be achieved without the use of any fossil fuel
- Provide an n+1 arrangement for system redundancy during maintenance
- Minimize all utility consumption to the greatest extent possible
- Reduce overall system footprint, height, and weight to fit within facility restraints
Anguil is one of the few industrial air pollution control providers that offers a full line of thermal and catalytic oxidizer technologies that also includes emission concentrators. The diverse technology offering allowed Anguil to evaluate each option and its applicability for the demanding project objectives.
The first decision was to route all ambient process air sources to a zeolite concentrator wheel. The wheel uses a zeolite substrate to adsorb the VOCs and HAPs out of the process gases and onto the concentrator surface. A heated stream, approximately 10% the original volume, is used to desorb the pollutants from the wheel. The result is a highly concentrated stream that is one-tenth the original volume. This significantly reduces the size, capital and operating costs of the downstream oxidizers that are paired with the concentrator wheel.
Anguil engineers made the decision to utilize Regenerative Catalytic Oxidizers (RCO) with electric heating elements to treat both the hot process stream from their curing ovens and the concentrated air stream from the concentrator wheel. This technology combination is often referred to as an RCTO. Employing catalyst inside a thermal oxidizer allows emission destruction to occur at much lower temperatures; 600-800°F (315-427°C) versus 1,400-1,500 °F (760-816°C). The lower operating temperature also provides for a much more reliable and smaller (physical size and KW rating) electric heating element. The RCO uses ceramic blocks as the heat transfer media allowing for 97% Thermal Energy Recovery (TER) from combustion. The combination of lower operating temperature and 97% TER made the RCO the best choice for minimizing utility consumption and ensuring low maintenance operation.
All three oxidizer systems and the concentrator wheel were to be installed inside on the 3rd floor of a building still under construction under an existing mezzanine that provided only 15’ of overhead clearance. Anguil designed all individual pieces so they could be lifted three stories using an external elevator and fit through a narrow overhead door. All three units were installed inline and connected via common inlet and outlet manifolds to reduce installation costs.
Once installation was complete, Anguil’s start-up technicians arrived onsite to complete final commissioning. Anguil’s technicians conducted operator training consisting of both “on skid” and classroom sessions. Test data has shown each of the systems is achieving greater than 90% overall emission removal and 97% TER.
- Anguil was able to listen to the customer’s needs and the unique requirements of an oxidizer system that can process up to 70,000 SCFM of VOC-laden air without the use of fossil fuels.
- The zeolite concentrator wheel was applied to the ambient temperature sources, greatly reducing the size of the downstream oxidizers and the associated utility requirements.
- Selecting an electrically heated RCO eliminates the need for a fossil fuel fired burner, a customer requirement. The use of catalyst allows the oxidizer to operate at a much lower temperature than a thermal oxidizer, minimizing the size of the electric heating element. The RCO was also designed with 97% TER, further reducing the utility requirements and the size of the heating element.
- The hot source from the cure oven was sent directly to the RCO inlet, having no negative impact on the operation and efficiency of the concentrator wheel.
- Supplying three identical systems each sized to process 35,000 SCFM allows the customer to process up to 70,000 SCFM of VOC-laden air while operating in the required n+1 arrangement.
- Each system was designed to minimize the footprint and height to the greatest extent possible, saving on valuable floor space inside the facility.
- The system efficiency and effectiveness have exceeded the design specifications.
At Anguil, we are experts in environmental efficiency through the design and manufacturing of air pollution, water treatment, and energy recovery systems. Our customers know they can trust our team to develop and deliver quality solutions to their unique environmental challenges. In one case, a large semiconductor chip fabricator wanted to reduce their environmental impact, maintain their productivity, and save on operational costs.
- Client needed an abatement system with over 100,000 SCFM (160,500 Nm3/hr) volume processing capacity and over 98% VOC removal efficiency
- Anguil compiled a system of a rotor concentrator wheel, custom-designed thermal oxidizer with a destruction efficiency rate (DRE) of >99.5%, and a specialized heat exchanger
- Each system was able to meet and exceed the processing capacity and destruction efficiency requested, with the processing capacity double that of the two previous systems combined
As a large semiconductor chip fabricator, this customer realized the environmental effects of their operation. The fabrication of semiconductor chips generates significant amounts of wastewater and waste gases, both of which require treatment prior to their release into the sewer system or atmosphere, respectively. As fabrication operations have grown, so too has the amount of waste produced and, consequently, the need for abatement technology.
The customer approached our team with a request for a new abatement system for their plants. They came to us to stay ahead of their competition by tackling the challenge of reducing their environmental impact without sacrificing their facilities’ productivity and output. While they were currently employing the use of two systems, each with capacities for less than 50,000 SCFM (80,250 Nm3/hr), they were looking for a more efficient and effective solution. Ultimately, they were seeking a system that doubled their SCFM volume processing capacity with a 98% VOC removal level.
Their exact system requirements were as follows:
- >100,000 SCFM (160,500 Nm3/hr) volume processing capacity in a single system with the same footprint as the two existing pollution control devices
- >98% VOC removal efficiency
- No upstream pressure fluctuations
After reviewing the customer’s requirements and discussing the project objectives with the customer, our team decided that rotor concentrator thermal oxidizers (RCTO) would be the ideal air pollution control solution. The solution that was designed and constructed featured a zeolite rotor concentrator wheel sized to handle more than 100,000 SCFM (160,500 Nm3/hr) of process air and a custom-designed thermal recuperative oxidizer (TO) with a destruction efficiency rate (DRE) of >99.5% and specialized heat exchanger constructed to minimize silica build-up and facilitate maintenance operations.
Once fully assembled, all three systems were installed on mezzanine levels of the existing plants. After installation, our technicians completed final commissioning and provided comprehensive operator training. Ultimately, the customer was left with a system that met their needs and a team trained to properly use that equipment.
At the end of the project, the customer was fully satisfied with the performance of all three systems. Each system was able to meet and exceed the processing capacity and destruction efficiency requested, with the processing capacity double that of the two previous systems combined and the destruction efficiency surpassing that of the one required.
Additionally, by replacing their old air pollution systems with our more effective and efficient system, the customer was able to save on floor space and operational costs.