MEMORY RESISTORS EMISSIONS MONITORING FEBRUARY / MARCH 2009 $9.50 (incl GST) NANOTUBE BUILDING BLOCKS THE FUTURE OF CONSTRUCTION
This article was supplied by Mustang Engineering. Brian Funke and Allen Ware are from BP Products North America, Texas City, Texas, US, and Jane Buchanan and Paul Glaves are from Mustang Engineering, Houston, Texas, US. For more information go to www. mustangeng.com. This article was supplied by Mustang Engineering. For more information go to www.mustangeng.com. Brian Funke and Allen Ware are employees of BP Products North America, Texas City, Texas, US, and Jane Buchanan and Paul Glaves are employees of Mustang Engineering, Houston, Texas, US. 32 ENGINEERING WORLD, FEBRUARY / MARCH 2009
Chemical engineering The BP Texas City site (refi nery and chemicals plant) has invested in a real-time air emissions monitoring system with the goal of improving compliance, assisting in mitigating emissions exceedance events and reducing manpower to generate reports. By Brian Funke, Allen Ware, Jane Buchanan and Paul Glaves Due to increasingly rigorous requirements for regulatory and permit compliance, organisations are seeking more from all compliance support systems. The ability to expand systems to encompass new, or migrate existing, regulatory calculations used to monitor environmental performance is vital. Planning strategically for a scalable and sustainable system has been shown to reduce overall compliance costs. Currently, much spending goes to implementation of short-term tactical solutions which are generally customised in existing software tools such as Microsoft Excel or Access. These solutions do not easily support changes to compliance monitoring and increasing demands for more emissions data at more frequent intervals or requirements from emerging emissions trading markets. In 2003, the BP Texas City site began the search for a strategic solution to meet its air emissions calculations and monitoring needs. The Texas City Refinery is BP s largest refinery worldwide and the third largest refinery in the US, with an estimated crude capacity of about 460,000 barrels per day. The adjacent BP Chemicals Facility manufactures a variety of key chemicals which are used as building blocks by other sites within BP s chemicals stream. Rather than deploy several costly tactical solutions for multiple new incoming air emissions regulations, BP Texas City decided to invest the time and resources up front to use Mustang/Ellipsys E!CEMS suite of software. The key elements of E!CEMS which made it the preferred solution included the ability to take raw process data and perform air emissions calculations in near real-time per applicable regulatory guidelines, the functionality to provide subsequent event detection and notifications based on the calculation results, and finally the ad hoc and automated reporting capabilities. To utilise the key functions of E!CEMS, users access and configure the system via web pages. Using individual network login IDs, all staff members have access to configured reports. For example, users may log-in and see warning events that indicate they are approaching permit limits and should take action. After the study on which software package to use, the first project implementation included a detailed design phase to develop the configuration that included design features to allow as much automation of calculations and data substitutions as possible. One longterm goal was to automate the emission calculations to reduce the effort required to generate reports. The trade-off is periodic review of the emission data to address process data issues that are inherent in any operating facility. Consistent and automated application of the rules and policies for data issues that commonly occur in the course of plant operation are now possible. As a result of the selection of a scalable system and a detailed work flow and configuration design, the site now has a system which automates air emission calculations, monitoring and reporting for the three separate projects. These individual projects have served to ensure compliance with various air emissions regulations from the Texas Commission on Environmental Quality (TCEQ). The TCEQ is the state-level agency responsible for implementation and enforcement of the federal and state air quality laws and regulations (eg US federal and state Clean Air Act). ENGINEERING WORLD, FEBRUARY / MARCH 2009 33
Batch Data Collection from Historian, Typically Hourly Averages Calculations Copied from previous applications or recreated Includes Aggregation as needed Batch basis Infrequent Human error Not easily reused No automated audit trail Manual Review of Data for Validation and Manual Data Correction without Automated Audit Trail A typical tactical solution was drawn up for the process of monitoring and reporting emissions at the plant. In 2002, TCEQ issued regulations on Highly Reactive Volatile Organic Compounds (HRVOC) and nitrogen oxides (NO x ) emissions for the Houston/Galveston area. These regulations include monitoring, testing, record keeping and reporting requirements and emissions site caps for atmospheric process vents, cooling water exchange systems and flares as well as a regional NO x cap with a requirement to calculate NO x emissions within 5% accuracy. HRVOCs are defined by TCEQ as ethylene and propylene for the seven counties making up the Houston/Galveston area. These counties were exempt from the emissions cap requirement but still required to monitor and calculate HRVOC emissions as part of the overall strategy to reduce ozone concentrations within A screenshot of a E!CEMS warning events screen with simulated data. the Houston/Galveston area. The first two BP Texas City E!CEMS projects were based on the aforementioned HRVOC rule and NO x Mass Emissions Cap and Trade Program. The third project was based on BP Texas City s Refinery-wide Flexible Air Permit. In Texas, a flexible air permit allows an operator more flexibility in managing operations by structuring the permit to best suit the facility s specific needs. A site s Flexible Air Permit may contain an overall emission cap for all sources per pollutant, a combination of multiple emission caps that cover groups of units, and/or individual emission limitations for individual pieces of equipment. During each of these projects, applicable federal regulations regarding performance standards and monitoring for stationary sources were also implemented. For example, federal regulations outline standards for the quality and frequency of incoming data measurements from Continuous Emission Monitoring Systems (CEMS) and how the data must be validated and averaged. Currently, the total number of hourly emissions calculated in the system by species is over 1250 for these projects. The emissions sources include CEMS and non-cems emissions points such as heaters, flares, cooling towers, two fluid catalytic crackers (FCC), atmospheric relief valves, tanks, two selective catalytic reduction units (SCR), the sulfur recovery unit (SRU) incinerator, and thermal oxidisers as well as controlled and uncontrolled product loading racks and docks. There are plans to expand this system even further to encompass automatic maintenance, startup and shutdown (MSS) and flare upset (malfunction) emission calculations. During each project s design phase, a standard architecture for the air emissions monitoring was used. The key elements of the 34 ENGINEERING WORLD, FEBRUARY / MARCH 2009
Chemical engineering Currently, over 1250 hourly emissions are calculated in the system at points such as heaters, flares, cooling towers and incinerators. PHOTO: BP ENGINEERING WORLD, FEBRUARY / MARCH 2009 35
Real-time Manual Data Substitution Automated Audit Trail Automatic Events and Notifications The E!CEMS configuration is designed to automatically collect, validate and aggregate data per regulatory guidelines. design ensure that the calculations are automated to the maximum extent possible. These included real-time data acquisition and automatic data recovery; automated monitoring and validation of data; CEMS and analyser downtime detection; integration of process and CEMS data to automatically calculate air emission performance values; automated data correction propagation; ability to correct data manually with all dependent value recalculated; and self documenting configuration. Particular focus was placed on data flow and automation to ensure that the configuration supported a proactive approach to compliance. The system configuration and work flow were automated as much as reasonable to ensure emissions related calculations were accurate and timely notifications of exceeding emissions targets were in place to support mitigation of emission events. The implementations at BP Texas City considered many additional factors in the design of the system configuration and work processes. The work processes and tools not only consider the data collection, calculation and aggregation which are typically implemented as an industry standard, but also include automated data validation and substitution. The goal was to automate these additional steps where feasible, per regulatory guidelines, and include automatic notifications as well as the ability to manually correct the data while automatically maintaining an audit trail. As no project implementation is without challenges, during the implementations the project team encountered issues from which they learned and to which they adapted. One of the most obvious challenges in projects of this scale is the consolidation into one common system of the massive amounts of data required to support air emissions calculations and mitigate air emission events. The Air Emissions Tool design and implementation required interfacing and buy-in from numerous groups within the plant, on both the refining and chemicals sides. Once the system was online, it was very important that stakeholders could easily have access to their data. Ensuring the configuration and calculation results were accessible to all of the plant staff in an easy to understand format has also been a significant investment. BP Texas City s up front investment into the Air Emissions Tool (E!CEMS) and the supporting projects has provided a platform to work towards a step change in air emissions compliance. The Flexible Air Permit E!CEMS project is ongoing. To date, the site has leveraged the system configuration in the areas of their work processes, including heater/flares/cooling tower/fccu/sru emissions calculations; downtime detection and tracking for CEMS HRVOC analysers; automatic data substitution for NO x rules which require the use of 24 hour or 720 hour maximum historical values as data substitution parameters; annual mass emissions Cap and Trade reporting and decision making both year to date and end of year totals; detection of unit downtime to zero emissions and to prevent erroneous downtime; detection of downtime, permit limit exceedance and operational data limit events; and calculation, event detection and notification of excess SO 2 emissions above regulatory limits from SRU incinerator upsets. The automation with respect to data validation and report generation allows site personnel to focus on other tasks, rather than processing the mass amounts of data manually. 36 ENGINEERING WORLD, FEBRUARY / MARCH 2009