20. Sep 2019

Metal mesh: Custom weaves for horizontal pressure leaf filters at ESIM Chemicals in fumaric acid production

Lower maintenance costs and greater process stability were the objectives of ESIM Chemicals with the comprehensive optimization of a horizontal pressure leaf filter used in large-scale fumaric acid production. Beside altered process settings, the complete redesign of the filter plate covering by GKD – GEBR. KUFFERATH AG is what delivered the desired success.

ESIM Chemicals produces chemicals for the agricultural sector, as well as intermediates with two business divisions at the Linz Chemical Park, Austria. The so-called basic intermediates also include products produced from Maleic Anhydride (MA). Production of fumaric acid, which is used as an intermediate for paints and varnishes yet also as an acidifying agent in the food industry and a raw material for feed formulations, is an integral part of MA production. Reliable filtration performance is critical for the entire process in maleic and fumaric acid production. At ESIM, a filter package comprising 28 filter discs performs a central task in the FUNDA filter used. Each of these discs measures one meter in diameter. However, urgent optimizations were required as a result of increasingly unsatisfactory process stability and high maintenance costs, as well as ever greater utilization of fumaric acid production. Although the filter reliably delivered a service life of three to four months for years, this was starting to get shorter and shorter until hitting a new low of just three weeks use. Beside numerous changes to the processing settings, the engineers responsible therefore decided to go with a filter package that had been redesigned by GKD. The aggressive mechanical, chemical, and physical framework conditions – with throughput of 6,000 liters, pH value of 3, long dwell times, and high temperatures – were placing great stress on the twilled dutch weave made of standard stainless steel that had been used for the filter plates until that time and thereby causing the frequent breakages of the stainless steel mesh. As such, GKD recommended switching over to a reversed dutch twilled weave (RDTW) mesh with a geometric pore size of 60 µm, produced from a custom material with altered weave type and assembly. The responsible foreman at ESIM Chemicals learned all about the technology of cold covering the filter plates with round mesh discs featuring a bent outer edge at the mesh manufacturer’s main facility in Düren. In future, ESIM Chemicals will therefore be able to place the fully flanged RDTW Microdur round mesh screens on the filter plate themselves and clamp them around the outer edge. All 28 filter plates and the supporting mesh were switched over to the redesign by GKD. The filter package produced from the higher grade stainless steel has been in use since this time. Its constantly stable filtration performance, efficient cleaning process, and record-breaking service life impress in the challenging continuous operations.