Editorial - VGB PowerTech Journal 10/2017
From the sideline to the action.
Analytical instrumentation in power cycle chemistry.
I first visited the then called “feedwater conference” of the VGB in the early nineties. Instrument manufacturers had their booths in the outer hall. Although we had our instruments on display we rarely ventured into the conference hall. Instruments for on-line measurements such as conductivity, pH and dissolved oxygen were used in many industries. As manufacturers we did not normally have any knowledge of the specific requirements of cycle chemistry. The power industry did not challenge that status.
Analytical instrumentation was left to the control & instruments department. Chemists were responsible for the laboratory and possibly the complex process analysers for silica and sodium. It is an interesting fact that manufacturers of instrumentation can be classified into two groups. The larger manufacturers started from the control systems and later added transmitters with sensors to their platform. Others have their footing in analytical technologies. Since then most manufacturers have completed their product range. Others have disappeared or have been absorbed by bigger companies.
Historically the important innovations in analytical instrumentation did result from research in the power plants. Cation conductivity, degassed conductivity and pH-calculation from differential conductivity are good examples. It took several decades for instrument manufacturers to integrate cycle chemistry know how into their analysers. As of today complete solutions for acid and degassed conductivity are available from several suppliers. Sodium and silica analysers were greatly improved and are now more reliable and serviceable. The new generation of instruments has played an important role in the formulation of the new VGB-Standard-S-006-00;2012-09 which contains recommendations for sampling and instrumentation. Most manufacturers participated in the discussion. The ongoing dialogue between the manufacturers and the station chemists is established but we have left the sidelines. We have definitely left the side lines.
There are however noticeable gaps. When it comes to new power projects and rebuilding or adapting existing plants, budgets are very tight. Contractors face tough competition, nonetheless the analytical side constitutes a relatively small cost in an overall project. It does not get the required attention. We have encountered inexperienced contractors forgetting to budget for sampling and instruments. It is a known fact that outsourcing engineering overseas has not added to the quality of technical documents. Instrument manufacturers have to rely upon the technical specifications. It’s not for them to indicate shortcomings or outright errors. Nevertheless they have a considerable large knowledge and experience in the field of sampling and instrumentation. Some EPC contractors use this knowledge to adapt their technical specification in a dialogue with the instrumentation specialist. This way they avoid unnecessary risks and often save time and money.
Station chemists now have a big selection of reliable process analysers to choose from. Numerous recommendations and guidelines can be consulted for their usefulness depending on plant layout and chemical regime. Serviceability and maintenance cost has yet to be improved. This being said a few questions are left unanswered. Dissolved iron and low level chloride as parameters have been discussed for decades without producing suitable instruments. Research continues.
This year‘s chemistry conference starts with several papers on film forming amines. Analytical methods to monitor these substances have not yet been discussed. Some manufactures of film forming products have attempted but no standard is approved. Given the many treatment products with often unknown chemical composition it is impossible to know what exactly should be measured. Treatment methods, frequency and sampling points are other questions to which we still have no answers to. We just don’t know enough to develop adequate instrumentation. Maybe a VGB workgroup could help.
Industry 4.0 or the internet of things is also discussed in the power industry. Cycle chemistry has been subject to automation attempts using expert systems. There were few installations. Why should a station chemist learn from a computer what he already knows. The key problem is the availability of data. Reliable process data must be available continuously. This is a big challenge because we must consider the full measuring chain from sampling to the sensor and from the transmitter to data transfer. That is where the internet of things starts. Only the automation of the sensing part can provide the basics.
Future challenges request a close cooperation between all stakeholders. VGB workgroups and conferences are an essential part. We, the experts for process instruments will do our share. In the middle of the action.