Is dual-containment pipe leak detection or effluent compliance keeping you awake at night? There are smart, sustainable solutions to save time and money.
Regulators, investors, media, and the general public—as well as the power generation industry itself—are all keenly aware of protecting health and safety in the process of generating power. Coal ash contains toxins, including arsenic, lead, and mercury, and coal ash spills affecting major rivers and communities have made regulation a public policy priority. The U.S. Environmental Protection Agency’s (EPA’s) final rule established national minimum criteria for the disposal of coal combustion residuals (CCR) or “coal ash.” The final rule sets out complex criteria for the management of active coal ash disposal facilities and for closing facilities that cannot comply with the standards, in addition to providing a regulatory exception for recycling and reuse activities that qualify as a beneficial use of CCR.
The power generation sector is working hard to comply with these complex challenges while balancing costs and resources. How can we ensure that the environment and communities are protected while also keeping electricity costs manageable? Smart, sustainable technology provides a solution.
The reliability of pipelines, ensuring that there are no cracks or leaks compromising health, safety, and productivity, is a critical component of any integrity review. A leaking pipeline can cause untold damage to the local environment, not to mention human health—whether that’s employees or people living in the locality. Resulting fines or lawsuits can also impact the profitability of an operation.
The good news is that new robust pipelines and smart technologies are being embraced by the power industry to enhance pipeline safety. This means peace of mind for all concerned while supporting productivity.
High-density polyethelyne (HDPE) pipelines have grown increasingly popular within the power generation industry, and with good reason, as they are less prone to corrosion than traditional metallic lines. However, there is a downside; there are very few means to check their integrity, especially when it comes to leaks. Further compounding this is the growing use of dual-containment HDPE pipelines.
Dual-containment pipelines provide an extra layer of insurance against leakage. However, they are even more difficult to assess. This is especially true when the inner pipe has been compromised. Relieving pressure on the outer pipe will typically indicate when there is a leak somewhere along the pipe section, but operators will be unable to locate the exact point.
Traditional Methods Can Be Problematic
Traditional exterior inspections of pipelines can be costly and very disruptive, requiring large excavations to expose sections of pipe for inspection. Inspecting pipes from the inside is not always possible as some are too small for a person to walk through. If a pipe is large enough, there are many safety and logistical challenges to overcome before allowing someone to perform an internal inspection.
Another challenge is that traditional walk-through inspections require draining a pipe. This can lead to prolonged downtime or, in the case of a water utility, disruptions in water availability for customers, as well as the cost of pumping equipment and manpower associated with dewatering. Another option is a closed-circuit television (CCTV) inspection of underground pipelines. However, it provides very limited data; it cannot measure pipe gradient or provide structural data on the integrity of the pipe wall; and it only provides a view of the pipe surface above the waterline.
Smart, Sustainable Solutions Can Save Time and Money
Xylem’s SmartBall technology was introduced to the municipal water and wastewater industry in 2005, addressing a gap in the market for how leaks were targeted and identified in water pipelines. Over the past 15 years the technology has expanded, and today the innovative PureHM SmartBall solves leak detection challenges in oil and gas pipelines across the world, overcoming the challenges posed by traditional inspection methods.
SmartBall technology offers an innovative and accurate way to locate the point of a leak inside the inner line of a dual-containment HDPE line, providing the outer line can be depressurized. As well as identifying leaks, SmartBall can be used to confirm containment or to map a pipeline.
A significant benefit of SmartBall is that it flows with the product in the pipeline so there is no requirement to dewater the line before an inspection. The onboard magnetometer collects magnetic field data that can identify areas of the pipe wall that are under stress. Its precision is another distinct advantage—SmartBall can detect pinhole size leaks. To date, the technology has inspected more than 45,000 miles while identifying approximately 3,000 active leaks.
Let’s look at how SmartBall successfully identified a jet fuel leak in a 24-inch pipeline at a petroleum depot in Egypt. After a reduction in its jet fuel supply due to a suspected leak, Petroleum Joint Depot performed isolated hydro tests on its 24-inch carbon steel pipeline to narrow down which section had the leak. Only one section failed the hydro test, which prompted the pipeline owner to look for a more precise solution to identify the leak location (Figure 1).
The innovative tool works by being placed inside a pipeline and uses an acoustic sensor to distinguish the unique sound of product leaving the pipeline. This makes the tool significantly more sensitive than conventional computational pipeline monitoring (CPM) leak detection systems because the acoustic sensor directly passes the source of the leak. The lowest documented leak located with SmartBall technology is 0.03 gallons per minute (gpm) with a pressure of 90 psi.
Leak Detection within 5 Feet of Location
SmartBall was inserted into the pipeline using a 14-inch tee spool for the 0.8-mile inspection. The entire inspection was completed in less than an hour with the pipeline operating with a flow of roughly 1.6 feet per second at 190 psi.
SmartBall successfully pinpointed the leak within five feet of its location in the pipeline enabling the operator to excavate, verify, and repair the leak. By quickly identifying where the leak was within the pipeline, Petroleum Joint Depot could return the pipeline to regular operation without a lengthy shutdown.
In a similar situation in India, SmartBall was used by the Indian Oil Corp. (IOCL) to identify leaks also within five feet of the leak location. The IOCL operates a 12-inch steel pipeline that transports lube oil from Chennai Port Trust to Tondiarpet Lube Blending Plant. After observing a pressure drop and a discrepancy between volumes pumped and received during mass balance, IOCL suspected that the critical pipeline might have a leak.
SmartBall was run through the 5.2 miles of pipeline twice to ensure a high level of certainty. The first survey identified two acoustic anomalies in between the third and fourth tracking sensors. The second survey added an additional tracking point between sensors three and four to improve the location accuracy. SmartBall had correctly identified two leaks on the lube oil pipeline enabling IOCL to repair the critical pipeline.
More recently, SmartBall has been embraced by the power generation sector. Currently the technology is being used in the U.S. Midwest to check pipeline integrity during a planned outage at a nuclear station. The pre-stressed concrete pipelines will be checked again during the next planned outage.
Another important component of system integrity is effluent remediation. As regulatory requirements in this area become more stringent, the critical final testing phase that determines if a plant’s effluent complies with current requirements can be challenging and costly.
Testing often requires extensive manpower—sourcing samples in remote locations, sometimes multiple times a day. Discharge permits typically contain both a daily limit and a monthly limit for total suspended solids (TSS), and most remediation operations have established their own internal limit, or “daily high,” that is set far enough below the regulatory permit limit to provide a margin of protection against violations. Other facilities have set up their systems to simply provide a wireless alert in the event of an excursion. Reducing the cost and compliance burden associated with meeting final remediation effluent requirements is another key driver of technical innovation.
Online TSS monitoring with a sensor such as Xylem’s YSI IQ SensorNet ViSolid Suspended Solids Probe significantly reduces costs and resources necessary for compliance. The sensor’s two measurement methods provide TSS readings that are accurate at extremely low concentrations (0.1 milligrams/liter), with repeatability of <0.015% or >0.0006 Formazin Nephelometric Unit (FNU). Having the ability to monitor TSS in real time and obtain accurate results that are repeatable and verifiable with random lab tests, allows users to automate functions such as controlling pumps transporting effluent, or start and stop pretreatment processes designed to keep effluent within permit guidelines.
Because the sensor measures TSS concentrations in real time with consistent accuracy close to that of laboratory analysis, some operators have modified upstream processes, such as flocculent dosing, for higher treatment and remediation efficiencies. The long-term reliability of the measurement is also important for automation.
A New Horizon for Coal Ash
Positive developments in the recycling and use of coal combustion by-products are also good news. In 2017, 64% of the by-products generated by coal combustion for electricity in the U.S. were recycled and used beneficially. As research of new uses (including the extraction of rare earth elements from coal ash) leads to commercial deployment, future demand will surely increase. Smart technologies are revealing new horizons for this decades-old industry.
—Jessy Parmar is a Business Development Manager for the Industrial Marketing team at Xylem, a leading global water technology company unified in a common purpose to create advanced technology solutions to the world’s water challenges. Parmar helps customers develop an overall fluid management approach centered on digital solutions aimed at solving efficiency, infrastructure reliability, health and safety, and environmental sustainability challenges.