Techs & Specs - National Insulation Association. Leveraging Refractories for Maximum Insulation and Reduced Energy Bills. Manufacturers and operators of industrial heating equipment (furnaces, boilers, and kilns) are continuously examining ways to reduce the large energy losses that occur through the surfaces of their heating equipment. The following items of information are intended to assist the process of BTP evaluation. Handbook of Chemical Engineering Calculations (R).A proven and effective way to combat energy losses and the resultant high energy bills has been to optimize selection of the thermal barriers (i. Some new and emergent thermal barriers in the market now are opening attractive opportunities to leverage refractories for energy savings and improve productivity while protecting the structural integrity and operability of heating units. Heat loss occurs through the walls of process equipment via conduction, convection, and radiation. In the case of industrial metal melting furnaces, these losses account for ten percent to as high as fifty percent of the total energy consumed in the melting process. The U. S. Environmental Protection Agency (EPA) estimates that a properly maintained insulating refractory system can improve the thermal efficiency of the heating process by as much as fifty percent. A U. S. Department of Energy (DOE) study on opportunities to improve industrial energy efficiency estimates that refractory improvements in heating systems could facilitate energy savings from 1. Btu per year in the near term to 8. Btu per year over the long term. These savings translate to a $1. U. S. Refractory materials are employed to protect the internal surfaces and contain the heat within the structure. They are usually nonmetallic ceramic or brick- like blocks. The assembly of refractory systems requires complex masonry- like skills because, in addition to walls, they must protect the many entry and exit ports on a vessel. The physical property demands on refractory materials, in addition to mechanical strength and thermal conductivity, are extensive and include: chemical composition and resistance, density, porosity, permeability, thermal expansion coefficient, spalling resistance, and thermal cycling robustness. Premature corrosion, erosion, and wear of refractories can lead to contamination of products, add to operating costs, and introduce structural integrity concerns to furnaces and boilers. Most refractory materials research and development (R& D) has focused on enhancing their performance as “refractories”—i. These are the properties that control maintenance requirements and downtime. In addition to providing protection to the shell, however, refractory systems can be designed to minimize heat transfer to the exterior, lowering energy losses and enabling more efficient equipment operation. Insulating refractory systems work to enhance energy efficiency in two ways: Reduce energy loss through the structure walls (thermal conductance); and. Minimize heat storage in the walls (thermal capacity), which lowers startup and shutdown losses. Innovative advances in refractory technology offer new energy- saving opportunities in equipment rebuilding and new equipment design by combining a range of refractory materials to achieve thermal insulation along with physical and chemical resilience at high temperatures. When selecting the proper insulation or refractory materials, manufacturers must make a balanced choice, examining the cost of the material versus the dollars saved in energy bills. It is not uncommon to come across configurations in which ten to fifteen different types of insulation and refractory materials are deployed in a single furnace or boiler unit. The impact of better refractories is unlikely to change external insulation requirements. These will remain about the same since the shell wall temperature is one of the key determinates of the structural design and external insulation is significantly less costly than refractory materials. This decision is made based on short- term costs, and it can be very costly in the long term. Piping Books - Download as Text File (.txt), PDF File. Piping Design for Process Plants - by Howard F. Barrow (Auth or) Piping Engineering Leadership for Process Plant Projects - by James Pennock (Aut. CHEMICAL REACTOR DESIGN FOR PROCESS PLANTS. Volume Two: Case Studies and Design Data HOWARD F. Cunningham Professor of Chemical Engineering The University of Texas at Austin Original Illustrations by JAMES R. Faculty Bookshelf - Chemical Engineering. Green engineering: environmentally conscious design of chemical processes. Process dynamics and control. Metal and Glass Manufacturers Reduce Cost by Increasing Energy Efficiency in Process Heat,” Fact Sheet, May 2004. Project Engineering of Process Plants. 2016 National Insulation Association. Variable Frequency Drives for Centrifugal Pumps. H., Project Engineering of Process Plants, John Wiley & Sons. Project engineering of process plants by Howard F. Rase, 1957,Wiley edition, in English. Gasification Project Final Report, published in. The Coal Preparation Block is composed of three plants from the Houston report. Emerging Insulating Refractory Technologies. The following emerging refractory technologies have been shown to improve the thermal efficiencies of various high- temperature industrial heating equipment. Micro- Porous Silica. A commercially available micro- porous silica- based material can be installed between the refractory lining and the metal shell of an industrial process heating unit. The material reduces convection, conduction, and radiation losses, which are causes of major energy loss in industrial process heating equipment. This material reduces convection losses because the microscopic voids or gaps between the ceramic particles and fibers are so small that the air carrying heat cannot travel through them. Although these particles are close together to form voids or gaps that minimize air convection, they are designed to be far enough away from one another to minimize the conduction of heat through the solid material. Finally, radiation losses are minimized because the material consists of specially selected particles called “opacifiers” that are designed to reflect, refract, and re- radiate energy and prevent it from passing through the microporous material. Since this material has very low thermal conductivity of 0. W/m. K at 1,4. 72. These liners have been shown to reduce the internal refractory/insulation thickness by as much as fifty percent and reduce startup and shutdown heating requirements due to the reduction in refractory mass. These liners are designed to withstand continuous operating high temperatures of up to 1,8. This monolithic refractory material offers greater dimensional stability, increased wear resistance, and improved thermal shock properties when compared to conventional materials. G- 5 has one- third the thermal conductivity of conventional refractory material, thus reducing heat loss from the walls of the heating unit and lowering the energy consumption. Instead of conventional refractory brick, G- 5 refractory material is applied to the heating unit by spraying the material on the interior of the structure, which reduces the downtime for refractory replacement when compared to typical brick refractory materials. As is true with any thermal barrier improvement in refractory, G- 5 improves the product to fuel use ratio. The material can be used in a variety of process heating applications including rotary kilns employed in the cement industry, boilers in the forest products industry, and furnaces employed in the metals and glass industries. This material was proven to sustain temperatures in excess of 2,0. The result is the development of a low- cost nanoporous ceramic based on alumina, chromia, and silica. The material is an aerogel- based ceramic. This material can be synthesized using inexpensive chemicals as opposed to using the traditional expensive solgel alkoxide precursors, reducing the cost of the raw materials by two orders of magnitude. In testing this material, it demonstrated approximately half the thermal conductivity as compared to the lowest density firebrick, thus providing far better insulation and reduced energy loss from the walls of the heating unit. The material also demonstrated only three percent shrinkage over nearly 2,0. Shrinkage is important to monitor because it can create cracks and gaps in the refractory and exposes the shell of the heating system to high temperatures and corrosive materials. Swelling causes additional stress on the refractory bricks, which in turn can put more stress on the shell and lead to spalling of refractory. These nanoporous composites can be applied in a variety of industries that involve processing large quantities of materials at high temperatures, such as in the metals, chemicals, refining, forest products and cement industries. More information is available on the DOE’s Industrial Materials of the Future website at www. New Refractory Materials for Black Liquor and Biomass Gasification. One barrier to using gasification for black liquor is the need for refractory materials that can withstand the extremely harsh operating conditions of high alkali concentrations, elevated temperature of 1,7. This corrosive environment results in significant losses of refractory materials and metallic components, causing structural and safety issues, thermal efficiency losses, and unacceptable maintenance costs and downtime. The current short refractory lifetime in black liquor gasification makes maintenance costly and does not fit the scheduled mill maintenance, which typically runs on an annual basis. Researchers from Oak Ridge National Laboratory, in partnership with DOE, developed improved corrosion- resistant refractories for gasifiers. The materials were developed by gaining a better understanding of the failure mechanisms of existing materials and using modeling to understand the fluid flow inside the gasifier. In 2. 00. 4, new corrosion- resistant spinel refractory materials developed as a result of this research were installed in an operating black liquor gasifier unit. When the unit was shut down after one year for inspection and maintenance, it was found that the new refractory material did not require replacement. Although initially this material cost more than the traditional gasifier material, it proved to have a longer service life. This material also has been shown to be able to operate at higher temperatures than tradition refractory materials, leading to an effective overall increase in energy efficiency. More information about this material and project is available at DOE’s Industrial Materials of the Future website, www. Conclusion. The choice of refractory materials is dictated by the cost of installation and performance. In the past, it was good business sense to use low- cost, less energy- efficient refractory materials. However, with escalating energy prices, new refractory and insulation materials that were once considered expensive are now turning out to be good investments, promising significant reduction in energy bills.
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