An employee of a starch product factory reported that a release of starch had occurred at the site at 7:20 a.m. The release came from the filtration cyclone of a production dryer. The installation was shut down at 7:30 a.m. The discharge lasted about 20 minutes, and the Inspection authorities for classified facilities were informed. The starch fallout had reached several nearby streets.

The release was due to an accumulation of starch in the filter, the non-detection of the starch level and the automatic shutdown of the installation after low pressure had been detected in the circuit.

The accumulation of starch was due to the formation of moisture resulting from a succession of shutdowns and restarts of the installation as well as the clogging of the inlet at the lock of the dryer’s transport section. The high level of starch was not detected due to the formation of an arch of product at the probe, which had been in perfect operating order. The control by low-pressure detection on the transport system did not allow the installation to be shut down, the shutdown condition being a pressure of less than 0.35 bar for 15 min., although this time had not been reached.

The operator modified the monitoring of the transport pressure (transfer of alarms to the supervision display and implementation of a mandatory on-site check in the event of an alarm), optimised the monitoring of blockages (installation of a new type of more efficient probe and addition of a level probe in each cyclone) and plans to carry out a study on the causes of repeated shutdowns causing humidity points in the product.