For planning of a production plant handling more than 50 chemical products, a comparison was made, taking into account economic and sustainable aspects .
A conventional system with four pipelines and a pigging system with one pipeline as shown in the diagram were used for this comparison. A comparison between the investment costs and the annual operating costs showed that the pigging system is clearly more advantageous than a conventional system design.
The pipeline was made of stainless steel with a nominal diameter of DN 50; a price of € 3 / litre was used as basis for the products. The product loss in the conventional system was calculated with 50% of the pipe contents.
Rinsing water, wastewater costs and energy costs were calculated at € 14 / m³. Product is changed four times a day, each time using 4 m³ of hot water.
The investment costs for the pigging system are based on higher pipe quality, pipe bends and pigging stations regarding surface quality and tighter tolerances, which all together leads to a very good pigging result in the emptying process.
Another big advantage of the pigging system is the reduction in process times.
A conventional emptying process does not only include high disposal costs and product losses, but also leads to an ineffective process time. One pigging sequence only takes minutes and immediately leads to a system which is ready for the next use.