coal power plant ash handling

In ash extraction water play an important role, but the management process often presents problems. Power plant operators are always looking for ways to safely repair unpolluted water bodies and reduce risks and costs. The advent of the upcoming generation total suspended Solids (TSS) technologies helps power plant operators reduce the costs and compliance costs associated with managing the ash dump.

In the fly ash control permit, TSS is the main parameter for controlling the quality of waste water. In order to constantly reach the TSS emission limits and avoid potential fines and other debts, a vast field of collection, verification, registration and communication is required.

According to TSS test results, most coal combustion residuals (CCR) operations retain or release factory wastewater. These tests take at least one day to complete, but usually take two to three days. The existing TSS test method for compliance verification is a time-consuming laboratory test that cannot be completed in the field unless it passes a mobile-certified field laboratory. The inherent lag time between sampling and verification brings unknowns to the repair process, often requiring the cost of field sampling and testing (over-compliance) to exceed factory permit requirements. This also increases the possibility of risk bottlenecks throughout the repair process.

As part of the permit specification, most plants have a maximum allowable discharge flow-only a certain number of gallons can be emitted in any 24hour period. The amount of emissions allowed depends primarily on the name of the regulation receiving the stream and the characteristics of the plant’s wastewater. After the plant has reached the allowable emissions for the day, the pump must be shut down until the next day.

The issuing license includes daily and monthly TSS restrictions. In addition, most remedies establish their internal limits, which are the highest value per day, which is set below regulatory limits to prevent violations. Due to the huge delay between field sample collection and final laboratory TSS analysis, many facilities have adopted this expensive and cumbersome irrelevant strategy. Exceeding zero days leads to higher levels of containment, which exacerbates the possibility of serious problems, such as water leaks from ponds during severe weather events. In addition, when the structure must drain but cannot drain, the pond or pond reserve is filled with more water to pump. Due to the maximum daily discharge limit allowed, the plant was unable to compensate for the difference by adding a pumping program on other dates, so zero days were restored. It’s a vicious circle.

Depending on the license, some sites test the TSS level multiple times a day. Other sites test several times a week. In both cases, testing requires manual sampling. Equipment must be tested internally or externally, which requires a certified laboratory. To reduce delays, some facilities will sign mobile-certified laboratories for full-time field testing of wastewater. It’s an expensive and time-consuming process no matter how you conduct your lab tests. To reduce these high costs and compliance risks, some coal-fired power plants have successfully adopted solid-state levitation sensors that use optical backscatter technology to measure TSS in real time to verify that their waste water meets specified requirements.

TSS is a physical measurement in the laboratory; it defines the effective weight of a substance suspended in a given volume of water. The measured value of the optical sensor is not an absolute unit. However, TSS has a linear relationship with diffusion and backscattered light coefficients. Light diffusion technology differentiates samples based on refractive index, size, shape, and composition. Backscatter is a method for measuring the light diffusion associated with TSS. The field probe is calibrated according to the analysis of the instant sample in the laboratory, and the measured value of light is read as the suspended solid value.

The TSS in water can be detected by a variety of optical sensing technologies and it has been known for many years that there is a good correlation between TSS and backscatter coefficient. However, the first instruments that use this method have not worked well in difficult applications such as coal ash repair. Poor performance is due to gaps in electronics, light sources and other building materials and control algorithms. The difficulty of keeping the sensor lens clean during operation in a real environment has also helped identify the limits of the first devices.

Pressures to comply with increasingly stringent new government regulations have led Xylem to focus its research and development efforts on improving and stabilizing the backscatter method for TSS forecasting. Xylem’s technical team has succeeded in eliminating and compensating for the most common sources of instability through the use of light scattering and backscattering techniques, as well as the improvement of LED technology and the development of a complex algorithm for determining the relationship between TSS and predicted TSS. As a result, the Xylem ViSolid Probe for suspended YSI IQ SensorNet solids is now used in hard wastewater streams to consistently and accurately measure TSS in real time with repeatability less than 0.015% or greater than 0.0006% FNU (Formazin Nephelometric Unit). Because the sensor is capable of measuring TSS concentrations in real time with constant accuracy close to laboratory analysis, some operators have modified the processes above.

The ability to monitor the TSS in real time and obtain accurate, reproducible and verifiable results through random laboratory testing, also allows users to automate functions such as pump control for pumping wastewater or sewage. Starting and stopping pumps designed to maintain wastewater within acceptable limits. Preprocessing process guidelines.

The same control system for the TSS probe can measure pH simultaneously (by adding a pH probe). If the pH of the wastewater is too high or too low, the controller can be programmed to turn on a small pump to add acid or alkali to adjust the pH to ensure that the upper and lower pH limits are respected. With online TSS monitoring, power plants no longer need to rely on off-site or mobile labs for TSS analysis. This greatly reduces the need for a large number of people to obtain samples at remote locations and allows operators to connect remotely for monitoring or troubleshooting.

Based on the online accuracy of the optical sensor, the TSS monitoring function can measure the TSS in wastewater in real time and can be used as an operating and management parameter in accordance with regulatory requirements. Continuous TSS measurements also offer facility owners the potential to significantly increase operational efficiency and reduce costs. Save labor and lab costs by eliminating the need to sample and test in the lab beyond the random sample size required to meet licensing requirements Long-term reliability of the measurement can also automate certain functions, such as controlling pumps and discharge valves, as well as starting and stopping pre-treatment processes, further reducing costs and increasing efficiency.

Real-time TSS monitoring also lets you optically reflect the fingers of your current backup files, provides real-time account of wastewater discharges, checks compliance reports and resists potential lawsuits. It can also be used to confirm the sincerity of a plant by exceeding the permit requirements and showing that the plant is a good environmental manager.

Source: VArious

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