Vacuum Evaporator Reduces Costs & Improves Quality for Butterfly Valve Manufacturer

The KSB factory at La Roche Chalais (24), a subsidiary of Germany”s KSB AG, manufactures AMRI brand butterfly valves

These valves are used in the construction, industrial, water, and electric power generation sectors. The production of these valves generates two main liquid wastes: soluble oils and rinsing water from the pickling and passivation of stainless steel parts.

The oils used to be removed by a waste collector while the passivation waters were treated in situ by a physicochemical station. On several occasions, the station discharge values could not be kept, and KSB was required to remove this wastewater also. To reduce costs and meet customer requirements, KSB decided to equip itself with an H2O vacuum evaporator.

KSB – H2O collaboration project

Current status
After a visit to the H2O stand at the “salon Industrie” trade show, Mr Masante, Maintenance Manager at the La Roche Chalais site, outlined his requirements.

Manufacturing at the KSB site requires a wide range of metal production and processing tools: for machining, degreasing, liquid penetrant testing, pickling, and passivation.

Once parts have been machined, they are degreased in an alkaline bath before surface treatment. Pickling and passivation help to strengthen resistance to corrosion. Active baths are sent to the physicochemical station while the cascade rinses are treated with ion exchange resins. Some of the regeneration eluates are sent to the station, as it cannot process the entire flow. The remainder is removed by a waste collector in the same way as the soluble oils and soil washing water.

For many years, KSB treated its water through a conventional physicochemical station with discharge to an urban wastewater treatment plant. In accordance with the agreement made with the “Communauté de Communes” (French federation of municipalities), discharges were monitored and analysed over time. However, this former station, with its vast footprint and storage volume, required diligent and binding monitoring to ensure compliance; complicated further by the added difficulty of the diversity and variability of effluents.

A ClearCat evaporator at KSB in La Roche Chalais (France) for the treatment of industrial wastewater on site.

Project launch
The search for an alternative solution for the replacement of the aging station brought with it the possibility of several options. Thus, studies and tests on various technologies or combinations of technologies were launched.

It became apparent that the evaporation solution alone simultaneously offered both:

• recycling of distillates,
• complete freedom from all discharge-related control constraints.

The project team at KSB chose this direction with a specification defining the quality required for grade B distillate recycling. Indeed, nuclear applications require very high quality rinse water. Furthermore, easy and automated operation, as well as maintenance which requires few resources, were key criteria in the choice of supplier.

Stages of the study

• Execution of a comprehensive review of the relevant effluent volumes and flows.
• Update of the inventory of products used (degreasers, soil washes, machining emulsions, active baths and pickling/passivation rinses). This part is crucial to the ability to carry out a review and thereby possibly isolate any potentially critical products or flows.
• Execution of laboratory tests at H2O to determine the suitability of the combinations. During this test, it was found that it might be beneficial to treat emulsions (soluble oils, soil detergent, liquid penetrant testing wastewater) separately from surface treatment rinse water.
• On the basis of the tests, hydraulic diagrams were drawn up, with two strictly separate treatment cycles:
• Cycle A: evaporation of rinse water from stainless steel pickling/passivation. The acid waters are neutralised beforehand to avoid any risk of corrosion to materials.
• Cycle B: evaporation of emulsions.
• Definition of upstream and downstream storage capacities for each cycle. The emulsions are stored in one tank and the rinse water in another. The diagram for distillate tanks is the same.
• Definition of required distillate post-treatment to meet quality requirements:
  o    Ion exchange resins for grade B
  o    Activated carbon used in a finishing capacity, to remove the last traces of COD.
• Definition of the average flow of the evaporator on the concentration factor obtained.

A VACUDEST® 250 ClearCat® type evaporator, able to treat up to 5 m³/day with a concentration factor of 60 for rinses and 13 for emulsions, meets the requirement. KSB decided on this vacuum evaporation solution and chose to embark on this path from the perspective of zero liquid discharge and thus distillates recycling. KSB will therefore no longer discharge water to the municipal station and will eventually be free of all discharge control constraints.

Visual comparison of the distillate in a traditional vacuum evaporator with that from a VACUDEST with ClearCat option shows that the advanced condensation stage of the ClearCat is a breakthrough in terms of quality of treated wastewater.

Operation and initial feedback
A year and a half into operations, the evaporator produces a very satisfactory result. In fact, Mr Masante, Maintenance Manager, says:
“The commissioning was very quick and the training comprehensive. We have therefore been able to recycle the distillate because its quality, far superior to that of the water produced by our former physicochemical station, allowed this. Indeed, its conductivity is below 1µS/cm.

The H2O service centre is at the same time competent, attentive and responsive. They call us back within the hour, or at the most, within 24 hours.

The distillate post-treatments have a finishing role only. The ion exchange resins are replaced every 4 months and the activated carbon every year.

In one year, we have produced only 6t of concentrate for a treatment capacity of 1,500 tonnes.
Lastly, the return on investment is less than 1 year.”

Conclusion:
To close, KSB confirms the suitability of the choice of the ClearCat® solution. The H2O service centre now takes responsibility for ensuring the availability of the machine, answering questions, carrying out key maintenance operations, and recommending improvements where necessary.

This facility was funded by the Adour Garonne Water Agency as follows:

• 50% as a grant
• 45% as a zero interest loan over 10 years

Author: Mr Dipl.-Ing. Laurent Dumas
France-West Sales Manager

H2O GmbH
Wiesenstrasse 32, 79585 Steinen, Germany
Phone +49 7627 9239-0 | Fax +49 7627 9239-100
Email info@h2o-de.com | Web www.h2o-de.com