When you choose (or are required) to upgrade or update your air pollution control system, you are opting to make a major investment in the ongoing compliance, productivity, and environmental initiatives at your company. Knowing this, air pollution control systems are by no means “cheap” in terms of initial capital costs—few pieces of equipment engineered with a decades-long operational life are.
While capital costs may be high, operating costs don’t have to be. Following our recent articles on reducing the costs of pollution control and the resources available from federal and state entities that could save you money or provide assistance, we would today like to look at one of the biggest factors that go into operating costs: Fuel.
Whether you’re looking to calculate the operating costs associated with a new system or are looking to identify potential savings opportunities for your current operations, we wrote this blog to share some of the biggest drivers behind fuel costs.
Fuel Costs and Efficiency in Air Pollution Control Systems
Many factors go into fuel costs in your pollution control systems. From the type of oxidizer to the different burner types to the concentration of the VOC ratio, the incineration process requires consistent heating and therefore consistent fuel.
Type of Oxidizer: Catalytic vs. Thermal / RTO
Different types of oxidizers require different temperatures to destroy volatile organic compounds (VOCs). Destroying a pollutant through combustion requires a specific amount of activation energy to be applied to the process air to convert a hazardous carbon-based chemical compound (like benzene or toluene) into carbon dioxide and water.
Knowing this, a catalytic oxidizer may provide lower fuel costs than a thermal oxidizer due to the lower heat required to destroy VOCs. As a catalyst binds to chemicals, it reduces the amount of activation energy required to complete the conversion. Lower energy needs, lower temperatures, lower fuel costs.
While these are often plausible products for some companies, there are many industrial processes in which catalyst poisoning is a reality (learn more about the types of catalysts used here). Therefore, this creates a reality where thermal destruction is the most reasonable option for manufacturers. Thermal oxidizers directly apply the necessary amount of energy to destroy VOCs, operating at temperatures ranging from 815°C (1,500 F) to 980°C (1,800 F).
Often requiring more fuel to heat, there are also ways to control fuel costs when using a thermal oxidizer.
When using a thermal oxidizer, there are two primary burner types, raw gas airflow burners and sealed nozzle each presenting advantages and disadvantages for different processes.
- Raw Gas Airflow Burner: In this environment, oxygen from the process steam is mixed with natural gas to create a stable, uniform, and clean flame. As there is no need to add additional fresh combustion air, there is no need to heat said air, resulting in less fuel used. Used in situations in which concentrations are stable, these are more efficient than alternatives but only have specific use cases.
- Sealed-Nozzle Burner: When an outside source of combustion air is required, the sealed-nozzle burner is used. As these introduce outside air for combustion, the air needs to reach the temperature necessary for use. These are able to be used in a wide range of situations and offer increased versatility depending on the processes.
For more information on documenting your needs, we wrote a 13-point checklist for specifying your VOC abatement needs. This will help you understand your options based on the exhaust rate, temperature of the exhaust, heat source, and more.
Potential Steps to Increase Fuel Efficiency
When working to increase the efficiency of your air pollution control system, it pays to take stock of your airflow, fuel ratio, and solvent levels, working to control each of these with manual adjustments or automatic controls.
In determining the fuel costs that go into running your oxidizer, you will need to document your emissions, noting the concentration and the type of VOCs you need to destroy, as these calculations will help you to determine the proper amount of air introduced for combustion.
These calculations are necessary as they will provide information on whether you may be introducing too much combustion air. If you are adding too much air, you will need more fuel to heat it.
Air and Fuel Mix
Another process for controlling the amount of fuel used in pollution control is to determine the proper air to fuel ratio. Possibly one of the biggest determining factors in your fuel costs, the air to fuel ratio determines the rate of combustion and the emissions generated. If this ratio is not properly regulated, you may be operating with less fuel efficiency than you should.
Checking the ratio of air and fuel is just one part of a well-designed and implemented maintenance plan. This will help you to control the ratio while reducing maintenance and fuel costs. Learn even more about how to achieve these levels by reading our blog on the three T’s of combustion: time, temperature, and turbulence.
Concentration of Solvent
Richer air burns more easily. For waste gas with more hydrocarbons, less heat recovery is needed to maintain low fuel gas consumption. If the waste gas is too rich, however, you may need to introduce air to lower concentrations to safe levels.
If exhaust air is lean, you can increase the concentration of the solvent ratio to a higher level, increasing the efficiency and lowering fuel costs of your pollution abatement system.
An example of this is the use of rotary concentrators when volume is high and concentration is low. With this, a manufacturer could reduce the SCFM and increase the concentration so that they could use a smaller oxidizer to destroy pollutants. For more information on determining solvent concentration levels, we invite you to read our article on the basics of flammability, which explores topics such as lower and upper explosive limits and discusses how to improve efficiency and mitigate risk.
Modern air pollution control systems will feature sensors that measure each of the aforementioned concentrations and adjust the levels accordingly. By automating these processes, you can consistently adjust fuel and exhaust concentrations to reduce the amount of fuel used and in turn, decrease operating costs.
At The CMM Group, we specialize in the design and manufacturing of air pollution control systems that enhance efficiency and reduce costs. Regardless which technology is best for your facility, we have the skills and knowledge to engineer a solution that fits your budget and needs. Learn more about your path to purchase by downloading our VOC Abatement Guide and contacting us for more details.