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Remote data communication in the process industry
At ACHEMA 2018, Lothar Gellrich gave some details about remote data communication in the process industry which was realised together with PHOENIX CONTACT.
The key requirement for the use of wireless technologies in industrial applications is that the technology must be as robust and reliable as a cable connection, even under harsh conditions.
With wireless communication, the data is transmitted by means of electromagnetic waves through free air space that subject to interference, such as electromagnetic interference, which can adversely affect transmission. In addition, reflections, fading, interference, and shadowing can occur. Despite these influences Bluetooth, Trusted Wireless and WirelessHART are interference-free thanks to their particular method of operation.
Level measurement on tanks with remote data communication
Structures such as measuring wells or water towers are usually located in difficult to reach areas. Data and control cables for connecting these structures have also not always been installed during the construction of the plants.
Bulk water metering with remote data communication
Drinking water is essential to life, which is why the supply of it is one of the most critical infrastructure sectors. Secure data transmission and communication with the control room is therefore essential. Water supply networks often cover an extensive geographical area. Data/control cables or the electricity provider’s power supply lines have also not always been installed with the construction of the water pipeline. In addition, operators now expect highly accurate and innovative water meters, which are wear- and maintenance-free and can be read remotely. Existing control and data cables are now often in such poor condition that they cannot be used for modern communication technologies.
Sludge level measurement on scraper bridges with remote data communication
Primary and secondary clarifiers are usually equipped with a rotating bridge. Process devices such as sludge blanket measuring devices are installed on the scraper bridges. The communication between the field devices on the scraper bridge and the process control system cannot be implemented with a cable connection due to the rotation of the scraper bridge. Because of corrosion or wear, the use of sliding contacts for data transmission is proven to be susceptible to interference and high maintenance, due to the low signal in this environment. A limited bandwidth for data transmission using sliding contacts is another aspect, which is why a wireless solution is often favored today.
Chlorine measurement in outlets of waterworks with remote data communication
Many municipal waterworks perform no permanent disinfection of drinking water. However, in many cases a process known as emergency chlorination takes place. The process is switched on in case of need, adding chlorine to the drinking water as a disinfectant. As soon as chlorine is added to the water, the legal limits must be monitored in the effluent. In order to monitor these limits as well as to ensure accurate measurement of the chlorine, online measuring technology is often used. Unlike conventional sampling and laboratory evaluation, this technology continuously monitors measurement values.
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