The Clean Air Act makes the Environmental Protection Agency (EPA) responsible for setting air quality standards regarding “criteria pollutants.” Among these pollutants is sulfur dioxide (SO2), a highly reactive gas that affects air quality and has the potential to cause respiratory illnesses in those exposed to it. Power plants that process fossil fuels are a primary source of SO2 emissions and other pollutants. To maintain compliance with the EPA’s SO2 designations, power plants look to temporary climate solutions and protective surface coatings to improve emission controls and prolong the life of the equipment used.
Using Temporary Climate Solutions for Emission Control Strategies
Emission-Controlling Solutions
Power plants use a variety of techniques to limit SO2 emissions and other pollutants, such as mercury-containing fly ash, ozone and carbon monoxide. A popular SO2 control technique is the installation of limestone-based flue-gas-desulphurization (FGD) systems with a lime spray dryer that employs spray-dryer absorber (SDA) scrubbers. The scrubbers have a rotary atomizer that uses slaked lime (Ca(OH)2) to absorb SO2 and create calcium sulfite (CaSO3) or calcium sulfate (CaSO4). During the process, a large number of atomized slaked lime droplets mix with hot flue gas, ensuring that the droplets dry and become a solid material before hitting the SDA chamber walls.
Tank Preparation
SDA scrubbers are vital for controlling SO2 emissions and maintaining EPA regulatory compliance. The success of FGD and other SO2 scrubbing processes depends on tank preparation, as it requires a special coating to protect it from corrosive conditions and abrasive elements. Considering the high operations and maintenance costs and high capital costs to install emission-controlling equipment, plant managers look to temporary humidity control solutions to extend the longevity of the SDA chambers, complete the tank preparation project on time and within budget, and ensure compliance with a plant’s SO2 permit requirements.
One of the biggest threats in SDA scrubber tanks is corrosion the steel surface just after the cleaning and preparation phase. To prevent the formation of rust, temperatures within the tanks must be at least 50 degrees Fahrenheit and relative humidity levels must remain below 50 percent.
With tanks taking up to a week to blast and prepare for the protective coating, projects may exceed their budgets and deadlines without temporary humidity and climate control solutions. A contractor, for example may have to blast a tank and apply the protective coating within the same day, prolonging the project and possibly compromising the coating’s integrity. Blasting and coating in sections without climate and humidity control is also problematic as it involves extra time and labor, and the overlaps in the coating may become future failure points.
Tailored Solutions
A temporary climate solution setup that works for one plant may not be appropriate for another. For this reason, it’s important to work with a company that will design a tailored solution that a contactor can use to maintain the ideal blasting, coating and curing conditions.
Once the climate and humidity control systems are in place, a contractor can blast, clean and paint surfaces without worrying about environmental interruptions, regardless of the weather, to complete a project as planned.
Preventative treatments are critical to the operations of power plants and their compliance with state and federal environmental regulations. Polygon offers custom temporary climate control solutions and remote monitoring services to ensure the ideal conditions throughout the life of a project. Our engineers integrate factors such as outdoor conditions, surface temperatures, airflow dynamics, ventilation requirements and more to keep the working environment ideal for your needs and comfortable for workers. Whether you’re beginning an SDA tank preparation project or need support for one that’s already underway, Polygon is at your service.
[Photo from Lisa Murray via CC License 2.0]
