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180 Sector EE measure Challenges
processes used in the chemical industries; consequently, they have high economic importance. Adjustments to process control are dictated by order of economic importance with the product quality first, followed by process throughput and finally utility reductions.
C&P Inter-plant process integration
This requires facilities to be adjacent, and have synergies (such as utilities) which are in close enough proximity to be shared. As such, this is more of an opportunity for new plant construction. In addition to technical and infrastructure requirements, there is a need for the establishment of frameworks that will facilitate the engagement of facilities from different companies, and overcome some key hurdles to utilities sharing, such as how facilities manage the dependency on a separate company with which they are integrated (i.e., what happens if the company supplying their steam requirements shuts down), how credit for the savings (cost savings) is split between facilities, and how opportunities between facilities are identified.
I&S; C&P;
NFM
High Efficiency Burner (Furnace)
High202 efficiency, regenerative burners can achieve fuel savings in excess of 50%, when compared with cold air burners. Potential high NOx-emissions may however limit preheat temperatures and hence energy savings. Also, the full benefit of the burners depends on the integration in the furnace. For low to medium-temperature applications, burner designs that achieve low-NOx (<20 ppm) usually allow for energy efficiency improvements. For high-temperature applications, NOx-emission reductions are limited by the necessary high flame temperatures needed. Modern burners that are well-designed to mix combustion air and fuel, however, reduce NOx emissions.
I&S; NFM Flue gas monitoring (Furnace)
Flue203 gases and combustion air take turns flowing through each regenerator, alternately heating the storage medium and then withdrawing heat from it. For uninterrupted operation, at least two regenerators and their associated burners are required: one
regenerator is needed to fire the furnace while the other is recharging.
Additional flue gas challenges include, mixed composition gases; wet and/or dirty gas; large and difficult to access pipes; wide flow range and distorted, swirling flow profiles, high humidity, temperature and pressure changes, corrosive and acidic gases, and cross-sensitivity from emissions gases. Inappropriate flow meters and sensors can cause field failures, compromise sensor integrity and create considerable servicing needs.
M; C&P;
P&P;
NFM;
FBT;
NMM; I&S
Sub-Metering and Interval Metering
Determining204 the locations, type and exact model of equipment requires an inspection of sensitive areas such as switch gear and motor control centres. This may require scheduling a shutdown unless weekend or planned shutdown time is available. The actual installation may require another shutdown. For electrical sub-metering, a plant may also have problems getting its local utility to schedule a time to temporarily shut off power. Gas utilities may be sensitive to the addition of metering equipment near their own meters. Once facilities address these equipment installation issues, they may still need to install the appropriate cabling and means of communications established.
202 Martin, N., Worrell, E., Ruth, M., Price, L., Elliott, R.N., Shipley, A.M., Thorne, J. 2000. Emerging Energy- Efficient Technology (Report No. LBNL 46990). Ernest Orlando Lawrence Berkeley National Laboratory
203 US Department of Energy, 2004. Improving Process Heating System Performance: A Sourcebook for Industry
204 Tutterow V., Schultz S., Yigdall J. 2011. Making the Case for Energy Metering and Monitoring at Industrial Facilities. https://www.aceee.org/files/proceedings/2011/data/papers/0085-000064.pdf
181 Sector EE measure Challenges
I&S; M;
C&P;
NFM
Exhaust Gas Heat Recovery (Furnace)
One205 of the key barriers is the inability to economically
capture/recover low-temperature heat with existing heat exchanger or heat-storage technology. Similar to dryers, technical constraints include, the potential precipitation and accumulation of deposits on the surfaces of a heat exchanger (i.e., fouling) which increases the overall resistance to heat flow; corrosion risk, due to the moisture content of exhaust gas; excessive power requirements for effective heat recovery; inefficient heat transportation network, which is dependent on a wide variety of factors, including the length of piping, the thermal connectivity of insulation, the pipe diameter, etc. Heat206 losses must be minimized before waste heat recovery is investigated. As with other measures, the heat recovery technology must be unobtrusive in relation to normal plant operations. The availability of space and the need to shut down and restart operations presents significant complications. Similarly it is important that whatever mechanism recovers gas heat demonstrates “maintainability,” whereby individual components within the system can be replaced without necessitating a process wide shut down. If using regenerators, at least two
regenerators and their associated burners are required for an uninterrupted process: one provides energy to the combustion air while the other recharges. Other207 technical barriers to heat waste recovery include limited space, since many facilities have limited physical space in which to access waste heat streams (i.e., limited floor or overhead space), and inaccessibility, where it is difficult to access and recover heat from unconventional sources such as hot solid product streams (e.g., ingots) and hot equipment surfaces (e.g., sidewalls of primary aluminium cells). Safety and operational demands that require egress/access around/above most melting furnaces, boilers, heaters, and other high temperature equipment.
NFM; R Advanced Heating and Process Control (Furnace)
Controls208 for thermal processing require reliable and affordable sensors and control systems that can withstand harsh environments without recalibration for a certain minimum time (on the order of one year). Better, low-cost sensors are needed to monitor important process parameters such as material property uniformity, temperature, heat flux, air/fuel ratio, process atmospheres (oxidizing and reducing), emissions, and shop-floor infiltration, as well as to control burning and detect flames and flame stability. Key barriers include: few direct process measurement sensors; few low-cost sensors that are rugged, accurate, non-intrusive, and easy-to-use and maintain; excessive failures and inaccuracies of thermocouples and other sensors; inability to reliably monitor and control critical product parameters
(temperature, chemistry, pressure); inability to reliably control processes; lack of smart controls; lack of cost-effective flow control devices (e.g., air/fuel ratio control).
205 US Department of Energy, 2001. Roadmap for Process Heating Technology: Priority Research & Development Goals and Near-Term Non-Research Goals to Improve Industrial Process Heating.
http://www1.eere.energy.gov/manufacturing/tech_assistance/pdfs/process_heating_0401.pdf
206 US Department of Energy, 2007. Improving Process Heating System Performance: A Sourcebook for Industry.
http://www1.eere.energy.gov/manufacturing/tech_assistance/pdfs/process_heating_sourcebook2.pdf
207 US Department of Energy, 2008. Waste Heat Recovery: Technology and Opportunities in U.S. Industry.
http://www1.eere.energy.gov/manufacturing/intensiveprocesses/pdfs/waste_heat_recovery.pdf
208 US Department of Energy, 2001. Roadmap for Process Heating Technology: Priority Research & Development Goals and Near-Term Non-Research Goals to Improve Industrial Process Heating.
http://www1.eere.energy.gov/manufacturing/tech_assistance/pdfs/process_heating_0401.pdf
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