Towards the improvement of steam-water cycles

The Steam and Condensate Quality Water Process Technology project focuses on obtaining better insights into the distribution and behaviour of conditioning chemicals that are used in steam-water cycles and condensate polishing.

In July 2022, PhD-Candidate Irina Valentinova Veleva graduated on the topic ‘Treatment of heavily polluted petrochemical condensate streams in view of reuse’. We talked to Irina on her research, the project results and the effects of her research on the process industry. 

Improving steam-water cycles 

Irina Valentinova Veleva is 35 years old and graduated in 2012 from her Masters program in Water Technology at Wetsus Academy in Leeuwarden in Collaboration with University of Twente. Shortly after, she started as a Researcher in Water Technology at HZ University in Vlissingen. In 2017, she started the PhD track at Ghent University where she studied the treatment of heavily polluted petrochemical condensate streams in view of reuse, also known as Steam and Condensate Quality Water Process Technology. Recently, Irina graduated bringing the project to an end.  

Irina: “The main aim of the project was to achieve a better insight in the distribution and the behavior of corrosion inhibiting chemicals or conditioning chemicals in the steam water cycle. We for example focuses on how to improve the treatment of off-spec heavily polluted condensates and to find alternative technologies to the conventional treatment method or the currently applied treatment at the Wastewater Treatment Plant (WWTP). This is necessary in order to achieve a better steam/condensate return ratio and to lower the water footprint and dependencies of petrochemical companies on fresh water sources.” 

Energy efficiency  

Another goal of the project was to look into ways that could not only increase the water circularity of the companies but to also achieve higher energy efficiency by reusing the available waste/process heat in the stream(s) coming from the production plant. “The goal of my PhD research was to treat one of the biggest off-spec heavily polluted condensate streams on the site of Dow, Terneuzen to the highest possible quality for reuse of boiler feed water and thus to increase the steam/condensate recycling ratio. In the scope of the project, we tested technologies such as membrane distillation (MD) with hydrophobic and oleophobic membranes and MD was also explored as a method for heat recovery from the stream. 

Also, membrane aerated biofilm reactor (MABR) which is an innovative biological treatment method based on bubbles aeration was studied. Additionally, after the MABR polishing technologies such as Reverse Osmosis (RO), Nanofiltration (NF), MD, and Granular Activated Carbon (GAC) were explored. The main goal was to bypass the WWTP, to release some treatment capacity, and to lower the load of toxic pollutants at the entrance of the WWTP. Currently, after the WWTP the condensate is reused as cooling tower supply water.” 

Finding a solution for water shortage  

What motivated Irina, was the fact that she was looking for and working towards finding a solution to an actual problem/challenge, by looking into ways for the petrochemical industry to increase their water circularity. The effects of such process improvement could significantly lower the consumption of fresh water and therefore increase the sustainability of petrochemical plants. This way, the petrochemical industry can also respond accordingly to one of the most pressing issues that society faces which is the shortage and constant need for high quality water. Irina: “It was also very interesting to look into the aspect of energy recovery and how this could make the production process more sustainable and efficient.”  

“ISPT had a very crucial and focal role in the project as it brought together research institutions such as Ghent University and KWR with industrial partners and companies as Dow Terneuzen, Evides Industriewater, Sitech, and Kurita. This created the opportunity to exchange knowledge and knowhow and to look together for solutions of the problems that the petrochemical industry experiences. Such cluster of varying partners with different expertise and experiences increased the chance of finding the most viable and suitable solutions of emerging and already existing problems of the petrochemical industry. It was my pleasure to be part of such motivating and inspiring project team and to learn from the best experts in the field and also to grow alongside them as the project progressed.”  

A step forward 

The project results are a step forward in steam-water-circularity. “We found that to have a successful treatment via membrane distillation of the tested highly-contaminated condensate there should be no chemicals with wetting the membrane properties and also no volatiles. It also became evident that the oleophobic membrane demonstrated better performance than the hydrophobic. But also interactions between the oleophobic membrane and the present chemicals were suspected. In terms of heat recovery, a conclusion was drawn that maybe there are more suitable ways than MD to recover and reuse the available heat from the condensate. For example, via heat exchangers. Also, in terms of effluent/distillate quality for reuse after the MD treatment was noted that there was no improvement in the quality of the obtained stream and that it is comparable to the quality of cooling tower supply.” 

This research gives a useful base for future examinations of these and other treatment technologies for reuse and recovery of heavily contaminated condensates. It reveals the advantages and disadvantages of the tested methods and gives a solid starting point for further examinations of these treatment possibilities and points towards the need for other options for recovery of heat than the tested membrane distillation. 

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