5 June 2018

How do you increase batch process safety in a silo?

When you think of chemical plant hazards, what usually comes to mind? Chemical exposures, poisoning, and fires or explosions due to volatile changes in the chemical mixture and/or temperature are some of the most prominent hazards, but it’s the obscure hazards that we need to re-focus our efforts on. Whenever solutions exist that make chemical plants safer by keeping people out of silos or off of roofs, for example, these should always be preferred.

This is what a plastic granulate (or TPE – thermoplastic elastomer) manufacturer realized when he was working with Siemens to upgrade the level device installed in the most critical part of his process.

Manufacturing of TPE is done in batches in silos. Every three weeks, operators begin a new TPE batch in different colors and with other characteristics or requirements. A side effect of this process is the creation of small amounts of ?ne particles that tend to form a sticky layer inside the silo. In this situation, the sticky layer coated the coned antenna of the level device that monitored the process, which required the silo to be cleaned after each batch production to guarantee a continuous and consistent product quality.

How did they clean the silo with their original level device?

The cleaning process used to be performed manually with a high-pressure cleaner. Manual cleaning enhanced workplace hazards by exposing the workers to chemical fumes and the possibility of falling into the silo or off of the ladder. During the cleaning process, operators had to visually check the cleanliness of the silo walls and the transmitter’s antenna by bending over and sticking their head into the silo. Added to that was the inconvenience of removing the level transmitter each time cleaning was required since operators couldn’t reach the horn.

In order for them to automate their cleaning process, they would need to change their level device since the horn would get damaged in the process. So, when the customer decided to replace the existing level device with a non-contacting SITRANS LR560 radar transmitter without an antenna cone, the situation improved immediately. The operator mounted the transmitter against the top of the silo, so the range no longer protruded into the silo and risked damage from continuous pressure washing. Since unnecessary dirt no longer sticks on the level meter horn or range, operators can now use an automatic spray system, which has several benefits to the customer:

To read more about this application, please click here.

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