The Madison Metropolitan Sewerage District (MMSD) faced continued operational challenges with its traditional/current acid-phase direct steam injectors in its acid digester facility, leading to frequent disruptions, downtime, and high maintenance costs. To address these issues, the MMSD sought an innovative solution to reduce foreign material plugging. This case study highlights how the continued implementation of the Hydro-Thermal™ Non-Obstructing Heater (NOH™) revolutionized the digester and anaerobic process, enhancing performance and reducing operational costs.
The acid-phase direct steam injectors (DSI) in the MMSD's acid digester building were over 12 years old, and because of the increased challenges in the MMSD system, they encountered performance challenges. They frequently experienced plugging and fouling issues due to the existing heaters pipe diameter not being able to easily pass foreign material up to 2”. These disruptions resulted in emergency work orders and interruptions in acid digestion, resulting in increased expenses in parts and labor.
The MMSD aimed to find a solution to mitigate plugging, enhance the acid digester's performance, and reduce maintenance costs. Reliability-centered maintenance principles guided their decision-making process. They called in Energenecs (a local engineering firm), which they used in the initial update in 2012, to research and bring solutions to the table.
The Recommendation: Non-Obstructing Heater!
Having reaped the benefits of the existing Hydro-Thermal Corporation steam injection units since the 2012 installation, they were excited to consider the new NOH as an upgrade.
Hydro-Thermal (HTC), a manufacturer of direct steam injector heaters, recognized over the years of implementation that there was an opportunity in wastewater treatment and anaerobic digestion processes. Because of its innovative mindset, HTC developed a non-obstructive solution called the NOH Heater that allows larger solids up to 4 inches in diameter to pass through the unit.
Using reliability-centered maintenance principles, district staff decided NOH was the ideal solution to replace the current system. With Hydro-Thermal having designed and supported the existing skid systems, the teams from Energenecs, MMSD, and HTC were able to design the units to fit into the current DSI system skids, which led to minimal piping modifications.
The implementation of Hydro-Thermal's NOH Heater led to a significant reduction in plugging, fouling acid digestion, and emergency work orders. Erik Rehr, Maintenance, and Reliability Manager at the MMSD, says, “Since installing and commissioning the first of two NOH Heaters in November 2023, the unit has run reliably with no failures. This eliminated emergency work orders, typically 2 or 3 per week for cleaning the previous heaters, allowing operations and maintenance staff to focus on more important corrective and preventative maintenance activities.”
Hydro-Thermal's NOH Heater solution for the Madison Metropolitan Sewerage District significantly improved acid digester performance while reducing operational costs. The district achieved operational reliability and cost-effectiveness by upgrading equipment with advanced technology.
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What you need to know about a Hydro-Thermal NOH heater vs. Traditional Heat Exchanger
Traditional methods like heat exchangers have long been the go-to solution in sludge heating. However, they bring challenges, including energy inefficiencies and maintenance complexities. This has paved the way for innovative alternatives like Hydro-Thermal NOHTM Heaters, presenting a direct and highly efficient method to address the shortcomings of traditional heat exchangers.
Energy Efficiency:
- Traditional heat exchangers transfer heat indirectly through a metal barrier, resulting in significant energy loss.
- NOHTM heaters, on the other hand, achieve a remarkable thermal efficiency of 100% by injecting steam directly into the process fluid, utilizing both sensible and latent heat.
Maintenance Considerations:
- Heat exchangers pose maintenance challenges due to condensation, necessitating the maintenance of low water temperatures to prevent fouling.
- NOHTM heaters feature a straight flow-through configuration that minimizes clogging, requiring no specialized tools for maintenance. Additionally, their wear and corrosion-resistant metallurgies enhance durability, even when dealing with abrasive materials.
- NOHTM heaters eliminate burn-on risks associated with traditional heat exchangers, ensuring a safer operational environment.
Space and Installation Efficiency:
- NOHTM heaters boast a compact design that saves valuable space, making them particularly suitable for installations with limited room.
- Easy integration into existing piping systems eliminates the need for a separate condensate return system, leading to substantial cost savings during installation.
For more information, visit www.hydro-thermal.com or contact Hydro-Thermal at
