Measuring digester process variables
As a part of the wastewater treatment process, sludge is separated from liquid in settling tanks and is then pumped into a series of digesters. Anaerobic bacteria inside the digester further decompose the sludge, releasing carbon dioxide and methane gas. Thus, the digester environment is potentially flammable.
The sludge is circulated through the tank and heated to an elevated temperature of approximately 35 - 55 °C to speed up the digestion process. Pressure, temperature level, flow, and PH are some of the variables measured in order to control the digester environment. Since methane gas it present inside the digester I.S. interfaces are used to safely make these measurements.
The PR electronics models PR 9202, PR 9106, PR 9113 and PR 9116 are isolated, intrinsically safe interfaces that allow safe measurements of the process variables found in the digestion process.