By Adeoluwa Olotu
Water is an essential compound that supports life on earth. From drinking to cooking, bathing, cleaning, the list of how water is used is extensive. Similarly, in the manufacturing industry, water is critical to business operation. It is highly sought after due to its unique properties:
- High specific heat – gives water ability to transfer large amounts of heat
- Easy transport – Water viscosity makes it easy to handle and pump
- Does not decompose
- “Plentiful, readily available and inexpensive” – Three fourths of the earth’s surface is covered by water
Figure 1: Specific heat of various materials (Source: Kaiser Science)
Over the last decade, as the world population and complexity has grown, the narrative of water being plentiful and inexhaustible has proven false. From the 1930s to today, the average daily consumption of water per person in rural America has increased nearly a 100-fold. Furthermore, with COVID-19, the heightened awareness and need for good hygiene has increased water demand and water consumption behavior. This broad shift is great for human health but not so much for water supply.
Likewise, in the energy and manufacturing industries, as the global need and demand for manufactured products increases, so does the need for more water at manufacturing plants to support increased production. While increased production is often welcomed and good for companies, the impact of higher water demand is becoming more challenging. The Global Water Institute projects that global demand for water by 2030 will surpass supply by 40%. If nothing is done to improve managing this problem. Consequently, this will increase the amount of water-stressed regions and affect 52% of the world’s population by 2050.
As mentioned earlier, water is essential to production processes, but in of itself does not make manufacturing companies any revenue. Therefore, water-related issues are often treated as the red
headed stepchild, and only get attention when they affect equipment reliability and/or cause production downtime. Additionally, although water demand has increased tremendously over the years, it is still largely viewed as a commodity and relatively cheap. In the U.S. the average cost for 1,000 gallons of water is only $6.00, making it very difficult to justify any water savings project. Even when a return on investment exists, water projects seldom stand a chance to compete for CAPEX against much higher yielding process projects. Besides water not generating revenue and is low cost, when it is recycled in manufacturing plants, the concentration of contaminants present in the water tend to increase with each cycle. The increased level of contaminants can impact equipment integrity in many ways and in some cases affect finished product quality, both of which can lead to huge maintenance costs and lost profits. It is easy to see how a combination of the above factors present very low incentive for water usage optimization in a profit driven industry.
Start with Changing the Mindset
A possible solution to this problem is having a mind shift from viewing water as cost of operation to a scare resource essential to both life and production. For a typical manufacturing facility, water accounts for less than 1% of the total cost of operation, but if a facility runs out of water, is the true cost of water less than 1% of total cost?
Doing More with Technology and Smart Data
After decades of raw data collection, we can now leverage technology to create smart data, allowing for actionable insights from real time data in the field. One area of application is with open recirculation cooling towers. These units reduce cooling water temperature by evaporation over a fill media. One challenge with these units is as heat is rejected in form of water vapor, water left behind becomes more concentrated in dissolved solids. The concentration of the dissolved solids in the cooling water poses reliability risks (scale and corrosion) to equipment especially heat exchangers, and therefore must be adequately managed. The risks are often managed by maintaining water conductivity below certain thresholds.
Reducing the water conductivity is accomplished by using a manual process called blowdown, which is essentially bleeding off concentrated water and making up with clarified river water. As heat rejection varies so does the rate of evaporation and concentration of water in the system. Other factors like seasonal changes impact water quality, which also affect the rate of concentration. Therefore, the manual process of blowdown is very inefficient with managing water utilization as the concentration ratio varies. By installing a conductivity monitor and automated blowdown valve, water will only be bled off when concentration ratio exceeds a setpoint. This real time corrective action, utilizing data and technology, can save millions of gallons annually.
In exploring the validity of this concept, I implemented automated blowdown on a small open recirculating cooling tower at a petrochemical plant along the Gulf of Mexico. The automated valve was installed on the return water header to the cooling tower and received relay signals based on online conductivity readings. Following implementation, cooling water blowdown was only limited to when conductivity exceeded 1800mmhos, thus increasing efficiency of water utilization without compromising equipment reliability.
Figure 2: Conductivity Improvement After Automated Blowdown Install
Operational Improvements Save Millions of Gallons of Water
This simple operational improvement translated into a 16.4 million gallons-per-year savings in fresh water. To put this in perspective, in a water-stressed region like Africa where the average daily household consumption is 5 gallons, the water savings from this small cooling tower could help meet the water demand of 9,000 households every year! Nine thousand! This is the narrative and mind shift needed in the industry to drive the completion of similar water savings projects. From a cost savings standpoint, a 16.4 million water savings only translates to less than $50,000 in cost reduction, barely moving the needle for big manufacturing facilities. The cost savings from these water projects should be viewed as the icing on the cake and not the determinant for whether similar project initiatives get funded.
In conclusion, it is no longer a secret that the world is facing a water scarcity problem. Therefore, energy and manufacturing industries need to change the old ideology of water being plentiful and “inexpensive”. Furthermore, the approach to water savings should now be viewed from the lenses of sustainability rather than cost reduction. This is especially important as the world population grows, and energy consumption and manufactured products continue to increase.
Adeoluwa Olotu has over 5 years of experience working in the petrochemical industry with a career spanning three countries including Nigeria, Cameroon, and the United States. He manages the industrial water treatment as well as chemical treatment for ethylene production at one of the largest refineries in North America. As a technical consultant, he specializes in troubleshooting both utilities and process problems, monitoring treatment programs, and implementing innovative chemical solutions that maximize safety and production. Olotu is also a member of the American Institute of Chemical Engineers (AIChE).