Krohne introduces Biogas flowmeter for variable compositions

Krohne introduces Biogas flowmeter for variable compositions

Industrial process instrumentation supplier Krohne announced the introduction of the new Optisonic 7300 Biogas ultrasonic flowmeter to the Southern African market.

The Optisonic 7300 Biogas is an ultrasonic flowmeter for low-pressure biogas, landfill and sewage gas applications. The flowmeter is ideally suited to measure biogas with a high carbon dioxide (CO2) content as well as small amounts of other media like hydrogen sulphide, nitrogen, hydrocarbons or condensation water, and has been specially designed to measure dry and wet biogas with variable composition.

High damping of the acoustic signals

The flowmeter overcomes the limitations of the ultrasonic principle in biogas applications owing to high damping of the acoustic signals by CO2 and high-water content in the biogas. Its signal transducers provide a stronger ultrasonic signal into the gas, and specialised signal processing enables better detection of small, strongly dampened acoustic signals.

These features, along with the mechanical design of transducers and transducer pockets, make the measurement insensitive to liquid and biological scaling. Krohnes features A maintenance-free full bore flow sensor without any moving parts.

Measuring tube is made of stainless steel

Owing to the hydrogen sulphide in biogas being corrosive when dissolved in water, the measuring tube is made of stainless steel 1.4404/316 ℓ and the transducers are made of Nace-approved grade 29 titanium for maximum corrosion resistance. Equipped with lap joint flanges to lower its overall weight, the measurement accuracy is specified at 1% of actual measured flow rate when calibrated with air. When 2% accuracy is sufficient, users can select a dry calibration alternative at a significantly lower price.

Optisonic 7300 Biogas features a built-in temperature sensor that facilitates direct measurement of methane content using calculation of the molar mass, in combination with the measured velocity of sound. This enables end-users to determine the exact methane content of the biogas necessary when it is used as fuel for gas engines in a combined heat unit. It can also provide calculation of gas flow volume to standard conditions by using an additional pressure sensor.