HOME > Case Studies > Industrial Automation > Showa Denko K.K., Kawasaki Plant

Showa Denko K.K., Kawasaki Plant

Valve diagnosis by specialist engineers, and a discovered anomaly not visible to human eyes

A smart valve positioner attached to an Azbil valve used to regulate hydrogen pressure in soda electrolysis equipment.

In discussions on making the plant smarter, Azbil proposed that the Kawasaki Plant use Azbil’s control valve maintenance support system and smart valve positioners as the basis for valve analysis and diagnosis, and the plant agreed.

One advantage for the plant was the fact that Azbil’s microprocessor-equipped smart valve positioners could be mounted on existing valves, including those made by other manufacturers. Valve operation data from the positioners is collected by the control valve maintenance support system utilizing IoT technology. The degree of valve deterioration and potential anomalies can then be checked easily with graphed data.

“Operation data on valves from any manufacturer can be collected, which enables us to visualize the operating status of all the valves in the plant. We decided that this was a very effective way to achieve a smarter plant,” explains Mr. Hino.

Valve operation data collected by the control valve maintenance support system is sent to Azbil’s remote center, where Azbil conducts a primary screening diagnosis, which originally was done every other month. If the result of diagnosis is “overhaul recommended,” the Kawasaki Plant asks Azbil for a detailed analysis and diagnosis as necessary. Backed by many years of experience in valve diagnosis, Azbil can provide valve analysis and diagnosis by specialist engineers for detailed items such as input-travel comparison and maximum operating speed. This service was the deciding factor in accepting Azbil’s proposal.

“Other companies also offered valve diagnosis, but Azbil’s proposal was different in that specialist engineers analyze the data using a wealth of knowledge and know-how. We would like to accumulate analysis techniques ourselves, so this service is the most important advantage for us,” says Mr. Arita.

At first, the Kawasaki Plant decided to try using Azbil’s products on a small scale. In August 2016, they selected 16 important valves in the soda electrolysis equipment at the Ogimachi site and started operation.

After introducing the smart valve positioners and control valve maintenance support system, they conducted a response test in which valve travel was changed gradually in 1% increments to check the operating status of the valves during a trial run after a periodic repair. Another manufacturer’s valve that controlled the hydrogen pressure was found to be hunting, as shown by a fine wavy travel signal. Although alarms on hydrogen pressure had been generated for some time, the cause could not be identified, but the result of diagnosis showed that it was probably caused by the valve. The Kawasaki Plant then asked the manufacturer for maintenance, and the manufacturer carried out an overhaul that included disassembly of the valve for cleaning and reassembly. After the overhaul, the plant checked the valve with the control valve maintenance support system and found that the hunting had stopped.

“If the valve had not been serviced, the problem could have affected the operation of the plant. We were able to find an abnormality that could not be identified by human eyes and that even the valve manufacturer’s specialist did not notice, because the control valve maintenance support system’s data indicated a possible problem,” explains Junichi Yoshitake of the Engineering Department.

A monitor for the control valve maintenance support system installed in a local control room (LCR) near the plant. It is used to monitor the operating status of the plant. The operator can check the data on valve operation in easy-to-understand graphs.

This article was published in April 2021.