There are several trends and solutions that are positively impacting the industry and one of the first trends worth exploring is ‘repowering’.
By Michael Fontaine, Vice President of Project Management, Falcon Project Consultants
How Repowering Works
Repowering involves replacing timeworn coal boilers with gas-filled turbines that send heat to a heat-recovery steam generator (HRSG), which feeds a steam turbine. The resulting system can increase electricity production and overall efficiency of the plant by as much as 40%. Plants owners can utilize these enhanced systems to reduce maintenance costs as modern systems tend to be less problematic relative to older ones. Correspondingly, the conversion to natural gas results in other savings because feed stocks are abundant, more affordable, and easier to transport to industrial sites.
As contemporary health and environmental concerns continue to push forward, several plants have already made the switch to natural gas. Internationally, plants in Mexico, China, and India are beginning to standardize natural gas, while domestically several states are beginning the conversion process.
Gas fired power plants utilize lots of water, like all power plants do. The boiler feed-water requires treatment to avoid problems that damage or impede the boiler’s performance such as scale and corrosion. Plant efficiency and by proxy plant profitability requires pure high-quality water. Depending on the feed water quality, varying methodologies of pre-treatment are necessary to eradicate impurities and suspended solids, and to adjust the water’s pH to a neural level.
Reciprocating and rotary gear pumps are commonly used to inject the precise dosage of chemicals needed for these applications.
Solving Contemporary Water Issues
Almost always, businesses in the United States have legal, ethical, or moral requirements to treat the water they use; whether they are CBD extractors, juice producers, product manufacturers, or businesses such as resorts and eateries. While there are several processes that can be used, the exploration of reverse osmosis (RO), pH adjustment, and scale inhibitors is beneficial.
Reverse Osmosis
By employing a semipermeable membrane to remove ions, molecules, and particles from water, the RO treatment process can effectively act as one of the key processes for water treatment solutions. The RO process works by demineralizing the water through the application of pressure that is greater than the naturally occurring osmotic pressure. The water consequently seeps through the membrane while the bulkier molecules or ions remain trapped in the membrane.
The demand for RO applications, and the associated treatment and maintenance applications that come with maintaining RO systems, has increased not only in the United States in places like California and Florida, but also internationally in in places like Saudi Arabia and Israel. Metering pumps are employed to dose chemicals that clean and maintain the RO membranes.
RO membrane fibers degrade in alkaline conditions because they are cellulose based. The degradation of RO membrane fibers leads to a loss of efficiency and long-term alkaline exposure leads to membrane replacement, which significantly increases costs for plants. pH adjustment and administering scale inhibitors extend the life of membrane fibers; both processes employ the precise dosing capabilities of metering pumps.
pH Adjustment
Raw pretreated water is quite typically slightly alkaline. Precise amounts of acids (typically hydrochloric acid) are precisely dosed to protect the membrane by adjusting the pH of alkaline water to neutral.
After the permeated or treated water passes through the membrane, the water may become slightly acidic. The pH is frequently re-adjusted using caustics like sodium bicarbonate to achieve a neutral pH to facilitate delivering the highest quality water possible. Metering pumps are mainly employed to inject the precise amounts of caustics required for the process.
While the requirements of pH balancing are not as rigorous as the requirements typically seen for municipal drinking water requirements, the schedule constraints are rigid because plants operate 24/7 and cannot function without copious amounts of treated water. Due to this reality, the pumps employed must be decidedly reliable and able to run unceasingly.
Following the initial treatment, process water flows to a flocculation basin where chemicals are dosed using metering pumps to aggregate precipitated particles, which allows them to be filtered more easily. During the next step in the process, coagulated particles settle in a basin where they separate from water and are sent to a sludge treatment facility.
Scale Inhibitors
Another water treatment application is administering scale inhibitors for cooling towers. The life-giving properties of water can encourage bacterial growth that can foul system surfaces; nonetheless, water is ideally suited for cooling purposes. Additionally, water dissolves gases (oxygen and carbon dioxide), which can corrode metals. Scale deposits and fouling can reduce heat transfer and diminish the plant’s efficiency and therefore decrease profitability if untreated. Precise doses of sulfuric acid or phosphate are added to the cooling tower water to mitigate scaling and to prevent fouling, thereby protecting plant equipment.
The process water must be treated prior to disposal; therefore, most plants have their own waste water treatment facilities, and these units administer an additional round of pH adjustment, in addition to additional treatments required to meet local environmental discharge limits.
Suspended solids, microorganisms, and mineral scales accumulate on membranes as a by-product of the RO process. Scale inhibitors are dosed by metering pumps on the RO membranes to extend the life of the membranes and to increase the efficiency of the treatment process. Furthermore, precise dosing with metering pumps reduces chemical costs and aids in preventing calcium-carbonate scaling. As RO membranes could become saturated with heavy elements that decrease efficiency and clog the process without scale inhibitors, the metering pumps that are used to dose the scale inhibitors perform an essential function in maintaining the plant equipment.
Safeguarding Plant Resources
Several OEMs in the water and wastewater industry have internal maintenance teams. Often times, plant personnel know exactly which spare parts they need to maintain their pumps. In the current environment however more plants are opting to leverage the expertise of external personnel by outsourcing knowledge and time intensive activities such as inspection and maintenance.
Uptime is critical especially in today’s environment; therefore, maintenance teams at power plants and other industrial facilities mandate the availability of critical parts and expert personnel that can be deployed 24/7.
Rotary gear pumps are typically the optimal technology for most treatment applications due to their seal-less design devoid of leak points for harsh chemicals to damage the pump or surrounding equipment.
Many plants are optimizing their finite space by utilizing pumps with smaller footprints because space is extremely valuable. Correspondingly, many plants are opting for vertical configurations because they are less susceptible to flooding, less problematic for maintenance, they do not require staff to crawl on the floor to access them. Moreover, ergonomic front pull out designed pumps can be repaired in place which minimizes downtime by eliminating the need to lock out/tag out the pump and move it to the repair shop-which, must be performed by union personnel in some areas.
“The path forward requires effort from government, businesses, and households to fully comprehend the challenges that are currently at hand as well as effective communication from all parties regarding ever changing variables.”
Safeguarding plant resources can further be streamlined by selecting pumps that require a limited number of parts and pumps that use symmetrical parts that only fit one way. Simplifying part replacement ensure that repair time is minimized.
For greater clarity, companies like Falcon Project Consultants can provide pumps and skidded systems directly to power plants and large OEMs that service industrial plants around the globe. More often than not, these OEMs do not specialize in plant maintenance; therefore, much of the servicing and repair work will be performed by a service company.
A Smarter Path Forward
Bluefield Research (Boston) has identified five key areas most impacted by the upheaval that will reshape the water industry long beyond the current health crisis:
These include digital asset management technology, and changes to water demand due to oil prices and increasing unemployment.
• Capital and Operating Expenditures
• Workforce Management
• Affordability
• Customer Communications
• Resilience Planning
• Capital and Operating Expenditures
• Workforce Management
• Affordability
• Customer Communications
• Resilience Planning
Before the SARS-CoV-2 pandemic, water infrastructure has been chronically under-invested and the pandemic has exacerbated pre-existing problems.
The new problems that have arisen will compel businesses to assess their operational vulnerabilities and to expedite their path to greater digitization for benefits like remote monitoring, remote work capabilities, and improved data collection.
The path forward requires effort from government, businesses, and households to fully comprehend the challenges that are currently at hand as well as effective communication from all parties regarding ever changing variables. Increased investment in field proven solutions will safeguard the nation by improving the sustainability and resiliency of our water resources.
The Bluefield Research (Boston) complete analysis is available at no cost and can provide valuable insight for environmental managers and individuals about strategies and opportunities in a world impacted by SARS-CoV-2.
About the Author:
Michael Fontaine is the VP of Project Management of Falcon Project Consultants. He specializes in finding solutions for the industrial processing industries. Please contact him at mfontaine@falconprojectconsultants.com