Reducing energy costs with pressure measurement enables flue gas to be used for drying gypsum products

The application

Gypsum is the base product used for making many building materials such as plaster, stucco, screed and plasterboard. The raw material is in the form of gypsum rock, which is heated in rotary kilns to remove the water content of the mineral before further processing. The kilns are very energy intensive as they are run on natural gas.

To optimize energy consumption, a system has been introduced to re-use use the waste flue gas for drying products during the manufacturing process. For this, the very low pressures in the combustion chamber and in the chimney ducts have to be measured with high precision. These measured values are used to control the speed of the exhaust fans and vents for drying, whilst maintaining optimum conditions inside the kiln.

The process data

Medium:Combustion air, flue gas
Medium temperature:Max. 80° C at the process fitting
Measuring points:Burning chamber, flue gas pipe
Pressure measuring ranges:-0.05 ... 0.05 bar, or -0.2 ... 0.2 bar

The solution

The ideal solution for this measurement application is the pressure transmitter VEGABAR 82. Its oil-free, ceramic measuring cell is sensitive enough to provide the small range and accuracy for the measurement of slightly negative pressure in the burning chamber and positive pressure in the flue gas duct. The user has made a comparatively small investment and yielded a significant reduction in energy costs. The sensor is a member of the VEGA plics® family, a modular instrument platform with standardized electronics and controls, which means simpler set up, easier operation and reduced spare parts.

User benefits

AdvantageDependable control through accurate measurement of small pressure ranges
AdvantageReduction of energy costs through optimal utilization of combustion heat
AdvantageSimplified spare parts stocking thanks to standardized plics® system