The City of St. Cloud, Minnesota, located near the Mississippi River, has a wastewater treatment facility known for its innovative sustainability initiatives. These include the use of biofuel and solar co-generation to produce electricity. This case study from Fluid Components International, shows how they were ablet to utilize FCI ST98 Flow Meters in the process.

The wastewater treatment process involves five steps, including UV disinfection for the liquids portion after initial treatments. The remaining solids are processed in an anaerobic digester, producing gases, liquids, and solids. The biofuel generated from these gases is cleaned and conditioned for use in a 630 kW combined heat and power (CHP) engine/generator system, which provides electricity and heat for the facility.

Accurate measurement of digester gas flow rates is crucial for the success of biofuel co-generation. The digester gas consists mainly of methane (CH4) and carbon dioxide (CO2) and can be explosive. Therefore, precise flow measurement is required for environmental compliance and safety.

The St. Cloud facility selected the FCI ST98 thermal mass flow meter for its reliability and suitability in the dirty, wet gas environment of the digester. These flow meters use thermal dispersion sensing technology, providing direct mass flow measurement with built-in temperature compensation. They have no moving parts, reducing maintenance costs and ensuring accurate gas flow measurement.

The ST98 flow meters were initially installed in 2010 for environmental monitoring purposes and continued to perform well when the facility added full biofuel co-generation in 2017. The meters were calibrated differently for wet and dry gas processes. Vortab Insertion Panel (VIP) flow conditioners were installed to ensure accuracy due to short pipe runs. These meters have supported the facility’s sustainability goals and power generation needs with no reported issues.

As an exclusive representative for Fluid Components International, Cross offers the complete line of FCI flow equipment throughout our territories in the mid-Atlantic area, including; Maryland, Virginia, and Washington D.C. Take a look at the full case study from FCI and contact a Cross process solutions expert to discuss how FCI products can increase efficiency in your operation.