Environmentally Friendly Cleaning Of Pipe Systems During Product Change

A major cost factor in industrial plants with frequent product changes is the complete cleaning of pipes and piping systems. Everything must be clean before the new product can flow through the transport systems. Apart from the fact that short interruptions are preferable in order to minimise production downtime, environmentally-friendly solutions are also increasingly in demand today.

In the case of water-based products, such as aqueous solutions, emulsions or dispersions, a water flush is often used to remove any remaining residues of the previously conveyed product. Depending on the purity requirements, more or less large quantities of wastewater are produced, which must then be disposed of. The costs for this often make up a large part of the operating expenses. In addition, industrial plants often contain critical substances that have to be collected separately and disposed of at great expense. Therefore, it is obvious to design the rinsing, the cleaning highly effective in order to produce as little wastewater as possible.

Often a pig is used, a cleaning or inspection device that fills the pipe cross-section and either simply travels through the pipe with the product flow (usually with oil) or has to be pressed through the pipe by extra pressure (water or compressed air). Problems with this method are geometric changes in the pipeline, fittings with tight radii or pumps, butterfly valves and backflow preventers. Such systems cannot be cleaned at all and may even have to be removed. In addition, more or less thick product films can remain on the inner surfaces of the pipeline, especially in product lines for dispersions or viscous solutions.

New Flexible Cleaning Method Works Efficiently And Sustainably

Established processes require a high degree of integration effort or generate large amounts of wastewater and thus disposal costs. A new system developed by ‘Hammann Engineering’ works efficiently and thoroughly with little water, produces little waste water and is easy to integrate into existing piping systems. The so-called Comprex process quickly pays for itself through saved disposal costs.

The cleaning method is based on the controlled, impulse-like addition of compressed air into a pipeline partially filled with water. This accelerates water blocks in the pipeline to high speeds of up to 20 m/s. This mobilises and discharges impurities, deposits or, in the case of product pipes, also residues of the transported product. In contrast to conventional water flushing, however, Comprex cleaning produces up to ten times less wastewater, according to the developer.

In initial tests under real conditions at BASF, it was shown that the amount of product-polluted wastewater produced can be reduced by an average of 70%. Last but not least, the operator saves considerable disposal costs every year and reduces the C02 emissions for incinerating the wastewater. This represents an important contribution towards sustainability.

 Source: Dr Till Schmidberger, Process Manager, BASF; Hans-Gerd Hammann, Managing Director, Hammann Engineering (in ‘Chemie Technik’, July 2019)

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