Heating orHeat recovery from high pressure gas to air
The problem 
YIT Vatten & Miljöteknik in Landskrona, Sweden, specializes in turn-key systems for production and handling of biogas. For Linköping Biogas AB the system is producing up to 1400 Nm3/h biogas from animal waste, clean enough to operate the city buses in Linköping City. In Enköping household waste is used for the same purpose. The biogas is corrosive. The flow is large, the pressure above 14 Bar and required efficiency is extremely high. In the process the biogas must be cooled down from over 130°C to a temperature below 40°C. In both plants air cooling of the biogas was preferred: - Warm air could be used to distribute heat in the building. - With outside air as cooling medium a water cooling system, with for instance dry coolers, could be avoided.
The solution - AirCross 21with nickel brazing
YIT carried out a long, intensive, but ultimately unsuccessful search for a heat exchanger that in a compact design could handle a large gas flow with extremely high temperature efficiency. A nickel brazed AirCross unit has now, both in Linköping and Enköping, a history since 2004 of problem free operation with unchanged high efficiency. Even during the warmest summer days the biogas is cooled to the required temperature.