October 2009
Less waste and better working conditions at Chemtura
Process optimization with Pulse Discharge Candle Filters
Chemtura Netherlands B.V. is a producer of Crop Protection chemicals such as pesticides and herbicides. When they were investigating a plant optimization in which filtration played a role they contacted Twin Process Filtration for a solution.
The solution was the installation of two Pulse Discharge Candle Filters, resulting in reduction of waste and improvement of working conditions for operators. Furthermore, the filters give a significant product recovery by reusing process liquid. Based on the great advantages for the environment and human working conditions the FARBO has decided to subsidize the optimization project.
Production of Dichlobenil
Since the early nineties Chemtura Netherlands B.V. has been producing dichlobenil - a base chemical for several pesticides and herbicides - through a renewed environmental friendly process. By means of a catalytic gas-phase ammoxidation reaction base chemicals form dichlobenil. The product is formed into crystals by a sublimation process. Crystals grow to a certain size to be captured with a band filter that captures particles down to 20 microns . However, when process conditions are not optimal also smaller particles are being formed. This leads to product loss and to heavy fouling of heat exchangers and pumps. To avoid fouling process operators are constantly busy to keep the process operational and bag filters are frequently backwashed and interchanged. To avoid product contact a solution had to be found.
Pulse Discharge Candle Filters
In the liquid stream after the band filter two fully automatic Pulse Discharge Candle Filters were installed. Particles that are too small for the band filter are recovered by the Pulse Discharge Candle Filters. After automatic cake discharge the recovered particles are recycled into the stream towards the bandfilter again. Because of the prolonged residence in the system, the particles have grown further and are now captured by the band filter.
The Pulse Discharge Candle Filter (PDCF) is a proven polishing filter in which a wide variety of filter materials can be applied. Therefore it is a vey flexible filtration method, which can be used for many other products as well. The filtration method is based on a vertically positioned filter element with a filter cloth attached around it. Unfiltered fluid flows from the outside to the inside and flows into the rising tube in the center of the candle. Cleaning of the cloth takes place by an air pulse or a fluid pulse form the filtrate side. While one of the units is being cleaned, the second one is in operation and thus continuous operation is achieved.
Process Control
A big advantage of the Pulse Discharge Candle Filters is that they can be fully automated. For Chemtura the two filters were completely integrated in their control system, so the operators could check the functioning from the control room.
Twin Process Filtration
P.O. Box 6042
4000 HA Tiel
The Netherlands
Phone: +31 344 630603
Fax: +31 344 630530