[ automation ]
measurement devices within compact small-scale electrolyser designs . The latest vortex flow meters provide two independent flow measurements in one meter body and require very short straight runs to perform accurate measurements . This helps to overcome this space limitation issue , while also ensuring safe operation of the electrolyser .
Accurate and reliable temperature measurement is also important . Thermowells provide the required accuracy for this application , but they add complexity to the design and increase the possibility of leaks . Ideally , temperature measurements are non-intrusive . One option is to take a surface measurement of a pipe . However , this does not typically provide the accuracy or repeatability required . A solution to this problem is technology that measures the ambient and pipe surface temperatures and calculates the process temperature via a thermal conductivity algorithm . This offers an extremely accurate non-intrusive temperature measurement that is also very easy to implement .
Flow control
Precise flow control is required , but this can be undermined by poor control valve performance due to incorrect valve sizing or selection and wear . Regular maintenance should be avoided for both cost and operator safety reasons . All valves and final control elements must be reliable in high-vibration , highpressure conditions and be able to operate without leaks . As with all process applications , selecting the appropriate valve is essential , with valves offering large rangeability to ensure accurate flow control , wide pressure and temperature coverage and designs that support easy maintenance . Application-specific , high-pressure valves that use double-stage actuators and block-and-bleed designs are necessary to adhere to strict shut-off requirements , especially in case of emergencies . Superior valve packing technology with die-formed expanded graphite that achieves the highest possible emissions class for their design should be used to meet emissions compliance standards , minimise product losses and increase safety .
Pressure protection is provided by pressure safety valves , but if these are oversized , then too much product is released . These devices must have seat tightness that prevents hazardous leakages . The latest true modulating safety valves allow operation at nearer to set pressure for
The world ’ s largest alkaline water electrolyser stack at HydrogenPro ’ s test facility at Herøya , Porsgrunn , Norway . Photo credit : HydrogenPro
28 Hydrogen Tech World | Issue 8 | February 2023