The American Electric Power (AEP) Clinch River power plant is located near Cleveland, VA which is approximately 500 km west of Richmond, VA. It generates electricity with three 237 MW coal-fired units. Owned and operated by AEP’s Appalachian Power Company subsidiary, the plant started operating in 1958.

Since 2004, AEP has invested more than $5 billion to retrofit the environmental controls at a number of its coal-fired power plants. Of this sum, about $2 billion has been allocated to this and other plants run by the Appalachian Power Company. This aims to reduce the emission of nitrogen oxide (NOx) and sulfur dioxide (SO2) from the burning of coal to generate electricity.

The Clinch River power plant is equipped with selective non-catalyst reduction (SNCR) systems. SNCRs are a refitted post-combustion technology that reduces the amount of NOx released into the atmosphere by injecting an ammonia (NH3) reagent into the flue gas. This induces a chemical reaction that breaks the NOx down into harmless nitrogen and water vapor.

Ammonia is a toxic gas and its emission contributes to ozone depletion. Ammonia slip, or the emission of ammonia gas into  the atmosphere, can occur due to incomplete mixing of the ammonia reagent with the NOx or the injection of excessive amounts of ammonia.  To avoid fines and shutdowns, it is desirable to keep fugitive ammonia emissions at or below the minimum levels mandated by the U.S. Environmental Protection Agency (EPA) and other regulatory bodies.

Downstream from the SNCR systems, it is also essential to hold the NH3 below 5 ppm and preferably to 2–3 ppm as this minimizes the formation of ammonium sulfate [(NH4)2SO] and bisulfate (NH4HSO4) on the preheater surfaces. Such deposits are hard to remove with sootblowers. A fouled preheater operates less efficiently and corrodes at a higher rate, leading to higher plant operating costs. In the worst case, the deposits can trap fly ash and cause a pressure drop in the preheater that can lead to a plant shutdown.

Additionally, while Clinch River does not sell their fly ash (for drywall, gypsum board, cement, etc.), some generating plants do, and the ammonia slip can contaminate the fly ash, giving it a strong odor and making it unfit for commercial sales. Excess NH3 can also increase exhaust opacity beyond regulatory limits, resulting in complaints and fines.

In 2006, the Clinch River power plant installed nine tunable diode laser (TDL) analyzers to measure ammonia slip from the SNCRs. However, these analyzers, which came from another vendor, did not provide sufficient availability to ensure that the compliance monitoring requirements could always be met. High maintenance costs and the accuracy of their readings were also operational concerns.

After conducting a months-long evaluation of several vendors’ TDL analyzers mounted on-site, AEP and Clinch River decided to install nine Yokogawa TDLS200 TruePeak analyzers to improve its monitoring of ammonia slip.

Study in Detail

US-based Rand-Whitney Containerboard had two goals when it decided to replace the distributed control system at its Connecticut mill - system reliability and a good relationship with the new vendor. But ABB and System 800xA have delivered a lot more.

Rand-Whitney Containerboard produces 250,000 tons a year of containerboard at its mill in Montville, Connecticut in the United States. When the mill’s distributed control system (DCS) became obsolete and system support grew increasingly difficult to obtain, Rand-Whitney knew it would have to replace the outdated system. The company formed a team to compare control systems from different suppliers and assess how those systems would work in the mill environment.

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Case Study by Yokogawa:  Total S. A. (Total) is a major oil and gas company with operations in more than 130 countries that span all aspects of the industry, including both upstream (exploration, development. and production) and downstream (refining, marketing, and the trading and shipping of petroleum products) operations. Total has been operating in Nigeria for 50 years and its deep-offshore oil & gas field development projects have been one of the main growth drivers in Africa. In Nigeria, the company operates through Total E&P Nigeria Limited (TEPNG) which carries out all upstream activities, including deep-offshore operations.

The Usan field is situated offshore Nigeria within oil mining lease (OML) 138, some 100 km south of Bonny Island, at a water depth of 750 m. Construction of the Usan FPSO by Hyundai Heavy Industries commenced in 2008 and was overseen by TEPNG. The vessel was launched in April 2011 and arrived at the field in July 2011. The Usan field came onstream in February 2012 and is able to yield 180,000 barrels of oil per day.

Usan FPSO specifications:

• Hull dimensions: 320 m long x 61 m wide x 32 m high

• Oil storage: 2 million barrels

• Oil processing: 180,000 barrels/day

• Oil-water separation: wash-tank inside the hull

• Seawater injection: 190,000 barrels/day

• Produced water treatment: 100,000 barrels/day

• Gas compression: 5.2 million standard cubic meters/day

• Topside dry gross weight: 25,000 tons

• Hull dry gross weight: 87,000 tons

• Living quarters: 130 people during normal operations (180 max.)

As the supplier of the integrated control and safety system (ICSS) for the Usan FPSO, Yokogawa Korea was involved from the early stages of this project. The delivered solutions include the CENTUM CS 3000 process control system (PCS) for the hull / topside control, the subsea control with the interface solution and overall control of wells and risers (OCWR), and the Plant Resource Manager (PRM) package for instrument management. These are integrated with third-party systems and software such as a process safety system, emergency shutdown system, fire and gas system, machine monitoring system, process data server, and operator training and maintenance system. Yokogawa’s vortex flowmeters were also installed in the field. From the very start of operations at this field, the entire facility has run safely and smoothly.

Read in detail Case Study by Yokogawa

Invensys, a leading supplier of state-of-the-art industrial software, systems and control equipment to the world’s major industries, has signed a multi-year, multi-million dollar contract with KBR, Inc. to supply its SimSci™ PRO/II® simulation software.

Under the terms of a corporate licensing agreement, Invensys will provide PRO/II steady-state simulation software to help KBR accurately model its process technology, used in both the designs KBR provides to its customers and the technology it licenses to the hydrocarbon processing industry. In addition, Invensys will provide on-site guidance to assist KBR during transition from the previous model.

“Before agreeing to standardize on PRO/II software, KBR needed new functionality to support them while they transitioned from a previous simulation tool,” said Tobias Scheele, Ph.D., vice president, design, simulation and optimization for Invensys. “Our Invensys developers worked hand-in-hand with the KBR team so that they can more accurately model and quickly deliver their processing technology to the market. We are pleased to provide these new features to KBR, as well as to deliver hands-on guidance and on-site engineering services to help them make the transition. We look forward to a long, mutually rewarding partnership.”

One of the refining industry’s leading simulation solutions, PRO/II software is a comprehensive simulation solution for process design, revamp and operational analysis. It is backed by more than 45 years of research and development and includes proprietary correlations to model heavy oils.

“We recognize Invensys’ strong commitment to the refining and petrochemical industries,” said John Derbyshire, president, KBR Technology. “This mutually collaborative relationship and the valuable assistance they have provided during the transition will help us continue to safely deliver key projects for the benefit of our global customers and other stakeholders.”