Cut Cost with Vacuum Distillation Systems!


Don’t Waste Money by Focusing on Investment Cost Only


Dipl.-Ing. Jochen Freund, Product & Business Development, Phone +49 7627 9239-310 Fax +49 7627 9239-103 H2O GmbH process water engineering, Wiesenstrasse 32, 79585 Steinen/ Germany


Which method is the best for the treatment of industrial waste water occurring in my production? Very often it is easy to answer this question: Vacuum distillation.


Vacuum distillation is established on the market as most feasible and reliable method for the processing of industrial waste water. But which evaporator is the best one for my application? How can I compare the different vacuum distillation systems on the market?


Lifecycle cost analysis (LCC) has proven to be an excellent instrument to prepare investment


decisions. To show the procedure the following example has been chosen: A metal processing company has to dispose of 2,500 m³ spent cooling lubricant emulsions per year. Currently they have disposal cost of € 80.00 per m³, amounting to € 200.000,00 per year.


If processed in a vacuum distillation system savings of € 1.2 to 1.3 million can be achieved during the ten year lifecycle of the machine. The company inquired with different suppliers of vacuum distillations systems and found out that comparison of quotations is not easy. Information regarding capacity and electricity consumption are not standardised. In addition this information is insufficient to determine feasibility of a vacuum distillation system.


Other important factors are disposal cost for evaporation residue and required man hours for operation and maintenance.


To get a better picture it was decided to prepare a simple LCC including the following costs: •Depreciation •Operation and maintenance efforts •Electricity consumption •Disposal cost for evaporation residue •Spare parts, consumables


Operation and Maintenance Efforts – Maintenance Friendliness and Quick


Service Pays for Itself. Modern vacuum distillation systems should run fully automatic. A reasonable, self explaining visualisation on the control system makes operation easier. On screen operation and maintenance descriptions support operators in doing their job efficiently. Only half an hour work load increase related to the operation of the vacuum distillation equipment increases total operation cost by more than 5%. This is a bigger impact than a price reduction of 10%.


Quick and reliable service provided by the systems supplier should be possible through remote


control. This makes the one or the other on site service unnecessary. In this context maintenance friendliness and reliability should be evaluated. Downtime is expensive. How quickly does the systems supplier react? How far away is the next service base and last but not least how quickly works spare parts supply?


Energy Consumption and Evaporation Residue Disposal – Evaporation Rate and Electricity Consumption


Influence Each Other It is common to state electricity consumption of vacuum distillation systems in Wh/l waste water treated. Certainly power consumption is important; however it is not the only important factor to judge feasibility of the vacuum distillation system. The power consumption of the evaporator at the end of a cycle directly depends on the evaporation rate reached.


Thus evaporation rate and power consumption are interdependent and have to be analysed


together. It might make sense to increase power consumption a little bit to increase evaporation rate, thus destruction cost are reduced. Costs for electricity do not fluctuate in the same range as the destruction cost. Reduction of amount of evaporation residue by 10% can reduce total operation cost of the vacuum distillation system by more than 4%. As information of different suppliers regarding evaporation rate vary it makes sense to put focus on this topic.


Finally, in the day to day business the right settings of the vacuum distillation system have to be found to minimize energy and destruction cost. To allow that all relevant data should be logged for respective analysis.


Pre and Post-Treatment –


The Total System has to be Looked at Not only the vacuum distillation system itself is of importance. Peripheral equipment can have big impact on the LCC. Not every process water can be distilled right away. Which pre-treatments are necessary to ensure proper and reliable functioning of the system?


Depreciation – Investment has Little Influence on


Total Operation Cost Depreciation of the system over the expected 10 years lifecycle amounts to about one third of the operation cost of the vacuum distillation system. On closer inspection one finds out that investment cost reduction of 10% reduces total operation cost only by 3.5%. Other factors have much bigger influence. Price is an important factor, but it should not be the main factor driving the decision in favour of a supplier.


Have floating oils or solids to be removed? Does the process water need neutralisation in continuous feed neutralisation equipment or can this be done space saving without costly equipment inside the vacuum distillation system? What happens to the distillate?


In the ideal case it will be recycled to enable zero liquid discharge. In addition valuable fresh


water resources are preserved, and depending on requirements, fresh water treatment cost are saved. Does the distillate quality meet the requirements of the production process or is a post- treatment prior to recycling necessary?


Even if process water quality is similar, distillate qualities of different suppliers of vacuum distillation systems vary. Thus it is useful to include post treatment cost, if any, into the LCC.


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www.pollutionsolutions-online.com • Annual Buyers’ Guide 2011


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