Air Monitoring 37


in particular for the measurement of gas and steam fl owrates. They are based on the vortex shedding principle, a phenomenon that occurs when a fl owing fl uid comes up against a bluff obstacle in its path - vortices are alternately forced onto the side of the body and then detached or shed by the fl ow. The frequency of this vortex shedding is proportional to the mean fl ow velocity and therefore the volumetric fl ow. This is read by a piezoelectric detector.


In a swirl meter, a stationary turbine rotor is located in the inlet. The medium to be measured is forced to rotate and fl ows through the meter tube in a thread like rotation. The rotation velocity at the wall is relatively small and increases towards the tube center until a stable vortex core is formed. In the expanding section of the tube, the vortex core is displaced and forms a secondary rotation, proportional to the fl ow rate, which is again measured with a piezo-sensor.


VortexMaster cannot be quickly ramped up to meet increasing demand.


Another method is the PEM (Proton Exchange Membrane) electrolyzer. This uses pure water as an electrolyte solution, avoiding the need to recover and recycle the potassium hydroxide electrolyte solution used for alkaline electrolyzers. Plants using the method can be small and so suitable for brownfi eld urban locations. It can also produce highly compressed hydrogen at between 30–60 bar for decentralised production and storage at refuelling stations.


The third and newest method is Solid Oxide Electrolysis Cells (SOECs). These use ceramics as the electrolyte and have low material costs. They operate at high temperatures and with a high degree of electrical effi ciency. As they use steam for the electrolysis process, they also require a heat source.


To make a success of green hydrogen production, there must be accurate and cost-effective methods of measuring parameters, such as fl ow. To encourage development in the industry, these must be suitable for both brown fi eld sites and greenfi eld developments.


Managing production


The production of green hydrogen requires a number of analytics and instrumentation stages to measure parameters such as hydrogen purity, pressures, temperatures and fl ow rates. This starts at the water input to the electrolyzer and the output of hydrogen and continue through to the hydrogen input to the purifi er and sending hydrogen for storage or to a distribution grid.


One of the most important measurements is the fl ow rate of both water, essentially the feedstock of the process, and the produced hydrogen.


Some of the most effective technologies for this are vortex and swirl fl ow meters.


Vortex fl owmeters have become the standard fl ow measurement method for many industrial process applications,


Because both types have no moving parts, mechanical stress is eliminated as a cause of failure. This makes the meters much more reliable and able to continue to work for longer without requiring shutting down the process for maintenance.


Vortex meters have the benefi ts of easy installation and operation, a low price and high accuracy of 0.65 percent of the rate for liquids and 0.95 percent of the rate for gasses and steam. One of their drawbacks is that they require up to 15 times the pipe diameter as a straight stretch pipe of before the meter and up to 50 times the diameter if a valve is upstream of the device. This could be prohibitive if installing them on brown fi eld sites where space may be restricted.


Swirl meters have the lowest installation costs, with far lower pipe length requirements, a large measuring span, and the highest accuracy of 0.5 percent of rate.


The CAPEX for an ABB SwirlMaster for example is higher than a traditional Vortex meter. However, when it comes to cost of ownership, the higher initial cost can turn quickly into signifi cant savings over the lifetime of the meter due to higher accuracy and the savings on pipe runs and associated space requirements.


Many installations will use a mixture of both depending on the layout and access of the particular measurement site. Both types can also have a pressure and temperature capacity added, turning them into mass fl ow meters.


As hydrogen is a very light gas, with the smallest molecule in nature, hydrogen permeation can be a challenge particularly for pressure measurement applications. The hydrogen can permeate through the metal diaphragm of a pressure transmitter, can collect and become trapped inside the diaphragm, eventually


destroying the instruments. ABB has overcome this issue with its unique H-shield technology, an impermeable alloy that prevents penetration by hydrogen molecules.


Measurement made easy


Increasingly, instruments are going digital, which has immense benefi ts over older analogue based units, including greater accuracy, range and depth of information. Digital technology offers operators and process engineers a highly detailed picture, both of the operating conditions of the process and the status of their measurement equipment.


Much more diagnostics information is available remotely, and an instrument’s confi guration can also be changed this way. Regular status updates cut maintenance time and costs, ensuring engineers are only deployed as needed. Data allows trends in the electrolysis process to be analyzed and turned into easily readable graphs. Using these, engineers can tell when an event, such as oxygen entering the hydrogen stream, occurred, as well as how changes in parameters could have caused it.


In the near future, many instruments will be connected over Ethernet, making them a node on the Internet and allowing data and commands to be exchanged from anywhere across the globe.


These digital instruments can be tied into a complete management system by ABB Ability SmartMaster, a verifi cation tool suite and condition monitoring platform for use with a range of ABB devices. SmartMaster verifi es the condition and performance of an instrument and can generate and store test reports for further analysis. Results can also be compared with historical measurements with a trending function.


Digital solutions such as vortex and swirl meters and verifi cation tools ensure that hydrogen production processes are effi cient and based on accurate information, as well as offering cost-effective installation choices – this will encourage the development of green hydrogen plants and help the world meet its targets for net zero.


References: [1] https://www.iea.org/reports/hydrogen


[2] https://www.iea.org/fuels-and-technologies/hydrogen


[3] https://energy.ec.europa.eu/topics/energy-systems-integration/ hydrogen_en#:~:text=The%20ambition%20is%20to%20 produce,in%20energy%2Dintensive%20industrial%20processes.


Author Contact Details David Bowers, Product Manager UK & Ireland Measurement & Analytics • ABB Limited • Address: Howard Road, Eaton Socon, St Neots, Cambridge PE19 8EU, UK • Tel: +44 (0)1480 475321 • Email: david.bowers@gb.abb.com • Web: www.abb.com/measurement


European Environmental Agency publishes new data showing signifi cant progress towards targeted reduction in the use of ozone-depleting substances


The European Environment Agency (EEA) recently published new data that indicated that the European Union (EU) made positive progress towards its target and global commitment to phase out the use of ozone-depleting substances last year in line with its commitment under the Montreal Protocol. The EU Member States’ production and use of ozone-depleting material was less than the amount that was destroyed and exported by a margin of 3,623 metric tonnes.


Ozone-depleting substances (ODS) are ubiquitous in refrigerants, polymers, pharmaceuticals, and agricultural chemicals. The good news was published ahead of the International Day for the Preservation of the Ozone Layer which occurs every year on 16 September to mark the signing of the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer. Eliminating the use of ODS is a vital element in protecting the ozone layer in the atmosphere.


The Montreal Protocol on Substances that Deplete the Ozone Layer came into force in 1989; its objective is to protect the stratospheric ozone layer by phasing out the production of ODS. The protocol covers More than 200 individual substances with a high ozone-depleting potential (ODP), including chlorofl uorocarbons, halons, carbon tetrachloride, 1,1,1-Trichloroethane, hydrochlorofl uorocarbons, hydrobromofl uorocarbons, bromochloromethane and methyl bromid, all of which are referred to as ‘controlled substances’ are covered by the Montreal Protocol. The protocol was amended in 2016 in Rwanda’s capital, Kigali, to regulate the use of hydrofl uorocarbons which are widely used as substitutes for CFCs and are potent greenhouse gases. The amendment was made because their production and consumption have grown signifi cantly over the last decades; developed and developing countries made fi rm commitments to make signifi cant steps to lower HFC production and consumption over the next three decades.


In 2022, The European Commission published a proposal for a revised EU Ozone Regulation. The new proposal aims to prevent the equivalent of 180 million tonnes of CO2


emissions by 2050. For More Info, email:


email:


For More Info, email: email:


WWW.ENVIROTECH-ONLINE.COM 61202pr@reply-direct.com and 32,000 tonnes of ODP


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