Summary

Dr. W Kolb bv, based in Moerdijk in the Netherlands, produces paper-manufacturing chemicals and non-ionic surfactants. These are chemical products used for such purposes as keeping solids in suspension or improving viscosity. Non-ionic surfactants are used in - amongst other things - detergents and personal care products. The total throughput at the Moerdijk plant is approximately 60,000 tonnes a year of various products.
The chemical batch process for making paper-production chemicals and non-ionic surfactants requires a reaction of acids and alcohols and ethylene or propylene oxides. A catalyst with a solvent is added and thoroughly mixed with the components in order to obtain a proper, complete ethoxylation reaction of all ingredients. The mixture temperature is raised after mixing and the solvent is removed by distillation. This process takes time and requires further ingredients, since part of the low boiling fatty acids and alcohol is extracted during the distillation process. The remaining distillate is treated as chemical waste after the solvent has been recovered.
The total process time is reduced and no further solvent is required, thus avoiding a distillation step in the process and a waste of ingredients. A part of the ingredients is added to a small mixing vessel, heated and thoroughly mixed with a catalyst in the meantime. The remaining part of the ingredients is heated and mixed in the main reactor vessel at the same time. When sufficiently mixed and heated, the smaller vessel is emptied and its contents are mixed with those of the main vessel. Under this arrangement no further solvent is required and so-called "hot spots" - for example, the build-up of lumps of catalyst on the wall of the main reaction vessel - are avoided.
The total project cost is NLG 570,000, comprising the auxiliary vessel, pipework, valves and controls. The energy saved amounts to 67,000 kWh for pumping and mixing energy and 160 tonnes of heavy crude oil to fuel the boiler, totalling approximately NLG 177,000 per year. The total payback period is therefore approximately 4 years. Application possibilities for projects of this kind exist mainly in the chemical industry.