Gerry Kaelin, FilterSense, USA, describes the ways in which optimising toward compliance with environmental regulations can reduce baghouse

Transcription

1 Gerry Kaelin, FilterSense, USA, describes the ways in which optimising toward compliance with environmental regulations can reduce baghouse maintenance and operational expenses. Making Sense Introduction Business owners, environmental managers, plant managers and engineering managers face continuing pressures to comply with environmental regulations, and the global trend is in the direction of even more stringent requirements. Facility managers recognise the costs they will incur to ensure compliance with government air pollution control standards. What they may not realise, though, is this same pollution control instrumentation and software will significantly reduce baghouse operating and maintenance expenses. This article reviews these often overlooked areas of cost containment. A clear return on investment results while achieving environmental compliance is assured. FilterSense has inspected over 1000 baghouses over the years and has seen first-hand the challenges that companies face to ensure the regulatory compliance of outdated equipment and instrumentation. These older systems are often a liability. The challenging economy, stagnant growth and limited budgets conspire to compound the problem. Quality compliance instrumentation and software puts a dent in decreasing budgets. Converting these perceived costs into a longterm investment to reduce plant-wide expenses can be a rewarding and money saving project. Reprint

2 State-of-the-art baghouse compliance instrumentation and software will: l Lower labour requirements. l Minimise downtime. l Maximise production. l Reduce energy consumption. l Minimise compressed air capacity requirements. l Lead to potential energy rebates. l Extend filter life. l Eliminate excessive cleanup costs. l Minimise product losses. l Provide a clean, healthy and safe work environment. l Avoid regulatory fines and associated plant shutdowns. l Maintain proper airflow. In addition to these benefits and meeting regulatory requirements, particulate emissions are minimised, making it a worthwhile investment. Maintenance benefits Integrated baghouse control and monitoring systems, as shown in Figure 1, allow for real-time continuous analysis of critical baghouse parameters and components to ensure proper operation and maximised filtration efficiencies. These advanced systems can instantly locate specific component problems within the baghouse. Without these diagnostic tools, plants typically spend hours (if not days) trying to locate these same problems within these often massive structures. By integrating particulate sensors, pressure sensors, temperature sensors, air flow sensors and Figure 1. B-PAC integrated baghouse control, sensing and diagnostic system. other process signals into the baghouse control system, problems are immediately identified. A specific row of leaking filters, a failed solenoid or a problematic or leaking diaphragm valve can be quickly detected and repaired. This minimises costly labour requirements. The energy losses that result from a single undetected leaking diaphragm valve can be astronomical over time. A failed solenoid will prevent a whole row of filters from pulsing, lowering filtration efficiencies and damaging filters. Minimise downtime and maximise production Many baghouses require round-the-clock continuous operation. When problems occur, manually locating the source of the problem is highly time-consuming and when production is halted, there are costly ramifications. For this reason, timely, quick and accurate diagnostics are essential. Integrated baghouse control systems offer instant, automatic identification of problems. Downtime is kept to a minimum as pinpointed component problems are quickly repaired. Production capacity is maximised while losses are minimised. On the other hand, an unplanned baghouse shutdown can be catastrophic for profits. Energy savings Pulse-jet baghouses consume large amounts of energy and compressed air. Reducing these energy costs should be a priority. Compressed air is used to pulse or clean rows of filters, removing excess dust buildup or filter cake. It is critical to ensure a balance: a certain amount of filter cake is essential to maximise filtration efficiencies. Small dust particles are embedded in the filter fabric and help to remove additional particulates. Alternatively, excess filter cake creates blockage and increases differential pressure, reducing air flow and preventing proper filtration. Other mechanical problems can result. A very common problem with pulse-jet baghouses is that they are over-cleaned, or in other words, pulsed too frequently on a continuous basis, often pulsing every 10 seconds. This is an enormous waste of energy. Increasing differential pressure is an indication of increasing dust buildup. However, there is no need to keep pulsing once the particulate is removed to a sufficient level. More advanced baghouse controllers such as FilterSense s B-PAC system with IntelliPULSE cleaning technology are well worth the investment. They provide optimal intelligent cleaning to fine tune the cleaning cycles

3 for maximised filtration efficiencies while minimising compressed air use and energy expenditures. Additionally, emissions are minimised with more efficient baghouse control. Every pulse creates a particulate emissions spike. The B-PAC advanced baghouse control system will automatically reduce particulate emissions as the pulse-rate is minimised with intelligent cleaning controls. Remove compressors from service Many plants lack sufficient compressed air supply, requiring a major capital investment in expensive new Figure 2. DP 20T non-clogging differential pressure transmitter. Figure 3. FilterSense induction sensing technology. air compressors. Another common problem is that of compressed air leaks throughout the system, either through cracked pipes or leaking baghouse diaphragm valves. Maintaining proper compressed air supply is critical for effective baghouse filtration. Quickly locating and repairing these leaks reduces overall compressed air requirements, potentially allowing a plant to put out-of-date compressors out of service. By considering new integrated baghouse control and diagnostic systems, plants may eliminate the need to purchase more costly air compressors. Energy rebates Based on the data obtained from engineering field studies, intelligent baghouse control and diagnostic systems such as the B-PAC system minimise energy consumption. The amount conserved varies significantly from one plant to another and even from one baghouse to the next. In many cases, these energy savings can be documented and presented by corporations to their local power companies to obtain energy rebates. In fact 45% energy rebate programmes are not uncommon and certainly help to justify new baghouse control investments. Reliable pressure sensors The reason many baghouses are pulsed continuously is due to problems inherent in low cost, low quality pressure sensors that routinely fail or clog. Without reliable and accurate differential pressure readings, efficient cleaning is not possible. As a result, maintenance personnel set baghouse controls to continuous cleaning as they cannot depend on these low-end pressure sensors to control the cleaning cycles. A quick, cost effective solution to this problem can be found with a reliable, non-clogging differential pressure transmitter. The FilterSense model # DP 20T shown in Figure 2 assures reliable non-clogging differential pressure measurement and regulates the cleaning cycles accordingly. The appropriate filter cake is maintained, resulting in a more constant air flow and differential pressure across the filter media. Extend filter life It is important to maximise filter life with efficient baghouse controls and monitoring. Baghouses contain hundreds or even thousands of filters. Replacement of these bags is a major consumable expense. Bag change-outs are labour-intensive and time consuming. When baghouses are continuously over-cleaned, the filter material is worn down needlessly, thus shortening the filter life and increasing the need for more frequent bag change-outs. Efficient baghouse cleaning is essential to maximise the life of these expensive filters. Other baghouse components are often

4 unnecessarily overused as well, such as diaphragm valves and solenoids. Efficient controls will extend the life expectancy of these parts. Reliable particulate monitoring Continuous, reliable particulate monitoring is a regulatory requirement for many baghouses. It is also an effective money saving preventative maintenance tool to detect the early onset of filter leaks and eliminate major particulate emissions catastrophes. Although the primary purpose is often for environmental compliance, the cost-cutting maintenance benefits are significant. Early detection of pre-visible small particulate leaks expedites filter replacement, preventing major particulate emissions. As a result, emissions and clean-up costs are minimised. Traditional optical particulate monitoring systems and Triboelectric broken bag detectors were plagued with a reputation for high maintenance and false alarms. These systems were unreliable, costly and labour intensive. Still, today, optical systems require periodic lens cleaning and realignment, while Triboelectric broken bag detectors require routine cleaning to remove the dust buildup and moisture from the probe. Otherwise, false alarms would result. A costly continuous stream of compressed air was recommended to keep the sensors clean and dry. In the 1990s, induction sensing particulate monitoring technologies were developed by FilterSense. These instruments are specifically designed for reliable environmental compliance and to eliminate the unreliability problems and false alarms of the high maintenance alternatives. The FilterSense EM Series and PM 100 particulate monitoring systems dramatically changed the industry (Figures 3 and 4). Principle of operation As particulate flows by the probe, a minute current is induced into the sensor. The signal is processed into an absolute output, which is relative to particulate levels. The specialised probe works in combination with the induction-sensing technology to ensure reliable operation. Conductive particulate, moist powders, corrosive gases and particulate buildup do not cause false alarms. Maintenance is minimal and an air purge is not required. The robust sensors are passive and free of electronics for durability. The control unit and electronics are remote for safe and easy accessibility and facilitate alarm setup and observation of the particulate status from the display. This technology reliably detects sub-micron size particulates below 0.1 mg/m 3. Automatic self-checks are designed to ensure that the particulate monitors perform accurately, reliably and continuously to meet environmental regulations. Independent gravimetric correlations (stack tests) confirm the linear relationship between the FilterSense particulate monitoring output and the actual mass concentration. Particulate monitors are also utilised for product recovery applications. Expensive and potentially hazardous product losses are kept to a minimum. These monitors can also be installed to protect expensive Figure 4. Probe-based particulate monitoring. Figure 5. FilterWare environmental compliance software; remote monitoring and reporting screen.

5 downstream equipment such as vacuum pumps, blowers and HEPA filters. A safe and healthy working environment The same systems that provide regulatory compliance also provide a healthier, cleaner and safer work environment. Specific problems are quickly diagnosed and located from a remote office setting and can then be quickly repaired. Troubleshooting time in the field is minimised, whether outside climbing ice-covered ladders and roofs, or inside a baghouse with high levels of micron-sized particulates. Timesaving Regulatory software for data logging, record keeping and reporting is primarily utilised by companies as required by environmental pollution control regulations. A secondary, less emphasised benefit is the significant time savings these systems offer from a maintenance management perspective. Compliance software, such as FilterSense s FilterWare System (Figure 5) centralises thousands of bits of information to one location within seconds. Any approved employee within an organisation can view specific baghouse and particulate emissions information across the globe with a simple login. An environmental manager at a corporation in Europe can quickly assess hundreds of baghouses at several plants throughout South America down to a single row. A specific failed solenoid, problematic diaphragm valve or a specific row of leaking filters can be isolated immediately. These systems put a microscope up to every baghouse to prioritise, ensure environmental compliance and reduce maintenance headaches. Smart alarms can be instantly ed, texted or phoned to local plant personnel to expedite repair. Many plants are still using manual record keeping methods for environmental compliance. This is highly time consuming and prone to errors. Automation software assures compliance and saves time and money. Conclusion A long-term perspective on environmental compliance reveals that investments in new regulatory-driven instrumentation, integrated baghouse control and diagnostic systems, particulate monitors, non-clogging pressure sensors and data-logging, record keeping and reporting software systems provide a clear return-oninvestment, significantly reducing baghouse operating and maintenance expense.