Case Study – RTO Service and Upgrade
- Location: California
- Residents: 379,000
- Industry: Municipal Waste
- Project Type: Service – Upgrade & Repair
- Equipment Type: Regenerative Thermal Oxidizer Upgrades
Executive Summary: The customer, a municipal wastewater authority, was operating a Regenerative Thermal Oxidizer (RTO) built by a competitor which required excessive downtime and media changeouts which led to unstable operating costs. Gulf Coast Environmental Systems was tasked with upgrading this RTO unit in order to reduce time spent shut down for maintenance and repairs.
Customer Summary: This customer is a municipal wastewater authority, providing reliable and fiscally responsible wastewater treatment and resource recovery services to over 379,000 residents and businesses throughout a 125-square-mile service area of California. The agency provides essential services for protecting the local ocean environment, preserving public health, and providing valuable water resources for the region.
Project Summary: Gulf Coast Environmental Systems collaborated with the customer to develop an upgrade package on a 3-canister 6,400 CFM RTO at a biosolids and wastewater processing facility in their California processing plant. Their RTO had previously needed service every 4-5 weeks, leading to shutdowns and expensive repair bills. The reason for the exorbitant service needs was a build-up of an ash-like material on the ceramic structural heat recovery media. Advancements in technologies over the years allow for upgrades on older equipment, that extend equipment life, provide higher reliability, and save money.
Solution: There were 4 major upgrades recommended to the Regenerative Thermal Oxidizer on-site.
1. Media change-out.
The media that was previously used in the RTO was not specifically designed to deal with the high amounts of solid material build-up caused by silica, and the lower pressure drop commonly associated with this application. Gulf Coast Environmental Systems recommended this media be replaced with a silica resistant series of structured media. The new media increases the amount of time required between washouts and media replacements, saving the customer a significant amount of money and downtime. The reduced silica build-up on the media results in lower pressure drops allowing for higher efficiency in heat recovery.
2. Increase size of heat recovery canisters.
Because of the larger gap media used to replace the existing media in the unit, it was determined that larger heat recovery canisters would be ideal in order to correct what would be an issue in airflow velocity caused by the change in media size. Expanding the size of the heat recovery canisters allows for a more forgiving media in regards to blockage or blinding. These changes help to maintain temperature, maximize heat recovery, supply proper residence time, and keep the burners within the design margin – all prolonging the safe operating uptime of the unit.
3. Supplemental Fuel Injection.
A supplemental fuel injection (SFI) system transfers the management of the combustion chamber temperature from the burners to the supplemental fuel injection system. This allows the RTO to maintain a setpoint temperature without burner operation, reducing fuel consumption. With the demand of the burners reduced, a large source of intense heat is removed from the process, minimizing potential silica formation. Other benefits include lower NOx emission levels and the reduction of demand on the burners prolonging the life of the equipment.
Summary: With the improvements made on the customer’s RTO, Gulf Coast Environmental Systems was able to reduce service downtime by more than 20%. The changes in media and heat recovery canister design make the RTO significantly more efficient and less likely to clog or shut down in the future. Avoiding untimely shutdowns and excessive maintenance turnarounds saves customer resources. Properly applied technologies, like the RTO, greatly reduce operating costs and increase efficiencies by reducing their dependence on supplemental fuel.
