Defining Thermal Manufacturing Thermal manufacturing relies on heat-driven processes like drying, smelting, heat treating, and curing to produce materials such as metals, glass, and ceramics, as well as downstream products such as electronics, vehicles, and machinery. As a result of its far reach, thermal manufacturing is estimated to directly and indirectly impact the employment of an estimated 5.4 million people in the United States at more than 101,000 establishments (U.S. Census Bureau 2009, 2012). These companies 97% of which are small and medium enterprises annually produce $2.9 trillion in total value of shipments (U.S. Census Bureau 2009, 2012). Figure 1 provides an overview of thermal manufacturing and the industries it impacts. Figure 1: U.S. Thermal Manufacturing Overview Thermal Manufacturing Equipment The type of equipment used for thermal manufacturing ultimately depends on the material undergoing thermal treatment and the desired properties of the final product. These factors determine the required thermal manufacturing process and the associated process atmosphere and temperature. Different 1
types of equipment can best achieve the desired properties of the final product based on varying atmospheres and temperature ranges, modes of operation (batch vs continuous), heat-producing energy sources, and heating methods (direct-fired vs indirect-fired). While some equipment is best suited for a single process, multiple thermal manufacturing processes can be conducted in some equipment designs. The following sections, organized by thermal manufacturing process, indicate the processes that are conducted in each thermal manufacturing equipment type. The following types of equipment are used in thermal manufacturing: Arc furnace Fluid heaters/boilers Fluidized bed reactor Thermal Manufacturing Process Atmospheres and Temperatures Manufacturers must ensure that their thermal manufacturing processes adhere to specific atmospheric conditions, including air composition and pressure, that directly impact the quality and properties of a product. They must also determine and maintain the optimal thermal processing temperatures, which range from room temperature to over 4,000 F depending on the material and process, and the processing duration, which can also affect temperature. These processing conditions are chosen after a manufacturer determines the type of material undergoing treatment and the thermal process needed to achieve the desired properties of the product. Using this criteria, a manufacturer or process implementer can make an informed decision about the required or preferred types of process heating equipment. Thermal manufacturing processes are conducted in the following types of atmospheres: Air/ambient Oxygen Ammonia Particle-Free Carbon-based Pressurized Dry steam/air Reducing Inert gas Salt Bath Helium Sulfur-based Hydrogen Vacuum Hydrocarbon The following sections include figures that outline the process atmospheres and temperatures based on thermal manufacturing subprocesses. Industry Input Encouraged As we do not have access to all process information, we welcome industry input to ensure the completeness and accuracy of these figures. 2
Curing & Forming Curing is the crosslinking of polymer chains in polymer-based materials. Crosslinking causes an exothermic reaction (generation of heat) that is further accelerated with the application of thermal energy. Curing is commonly applied in the fabrication of composites and ceramic coatings. Forming is a process that shapes plastic resin, polymers, glass, or rubber into a variety of configurations (e.g., rolls, containers, automotive parts). In thermoforming, a thermoplastic is heated and forced against a mold until cooled. Curing & forming processes Figure 2: Autoclave include Curing/Postcuring, Glass forming, and Thermoforming. The equipment and conditions for each of these processes is outlined in the following figures. Table 1: Curing & Forming Equipment Fluidized bed reactor Curing/ Postcuring Glass Forming Thermoforming Table 2: Curing & Forming Process Atmospheres Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Curing/Postcuring Glass Forming Thermoforming Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum 3
Figure 3: Curing & Forming Process Temperatures Curing/Postcuring Ceramic coatings: 266 F Polymers: 70 F 780 F Glass Forming Glass: 900 F 3,180 F Thermoforming Polymers: 260 F 720 F Drying Drying is the removal of water that is not chemically bound to a material. It is most commonly used to reduce the moisture content of raw sand materials like clay, stone, and glass. Examples of drying include the use of direct-fired heaters to dry pulp at paper mills and the use of conveyer-type dryers to remove water from powder compounds in chemical and pharmaceutical manufacturing. Drying is also used during petroleum refining, textile manufacturing, and food production. The equipment and conditions for drying are outlined in the following tables. Table 3: Drying Equipment Figure 4: Conveyor dryer Fluidized bed Drying 4
Table 4: Drying Process Atmospheres Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum Drying Figure 5: Drying Process Temperatures Drying Brick: 100 F 400 F Clay: 210 F 1,650 F Pulp: 100 F 180 F Silica: 392 F Extractive Processing Extractive processing involves the conversion of mineral ores or inorganic materials to metals or other intermediate products. Three key extractive processes include calcining, smelting, and agglomeration. Agglomeration, also called sintering, is the grouping of smaller particles into a large cluster by applying pressure or heat below the melting temperature. Calcination is a thermal treatment performed in the presence of air or oxygen to remove chemicallybound water from a material (as opposed to free water removal, which is known as drying); this process is commonly used in the production of petroleum coke, lime, cement, wallboard, and pulp and paper. Smelting is a thermal or chemical treatment used to extract metal from ore; common smelting processes include steel, aluminum, and magnesium smelting. The equipment and conditions for Extractive Metallurgy are outlined in the following tables. Figure 6: Electric 5
Table 5: Extractive Processing Equipment Fluidized bed reactor Calcining Smelting Agglomeration Table 6: Extractive Processing Atmospheres Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum Agglomeration Calcining Smelting Figure 7: Extractive Processing Temperatures Iron: 2,282 F 2,462 F Agglomeration Smelting Aluminum: 1,724 F 1,832 F Copper: 2,100 F 2,600 F Lead: 1,650 F 2,200 F Magnesium: 2,732 F Steel/Iron: 3,000 F Green coke: 2,192 F 2,462 F Gypsum: 250 F 300 F Limestone: 1,436 F 2,444 F Calcining 6
Fluid Heating Fluid heating is the application of heat to a gas or liquid (i.e., thermal fluid) within a closed-loop system. These systems often rely on a series of heat exchangers, blowers, and pumps to apply thermal processing heat to a variety of products and materials. Examples of fluid heating include distillation of crude oil into separate components and heating of fluids in chemical manufacturing to achieve ideal processing conditions. Fluid heating processes include Air Heating, Catalytic/Thermal Cracking, Distillation, Hydrotreating, Liquid Heating, Quenching, and Steam/Catalytic Reforming. The equipment and conditions for each of these processes is outlined in the following tables. Figure 8: Fluid heating columns at petrochemical plant Table 7: Fluid Heating Equipment Fluidized bed reactor Air Heating Catalytic/Thermal Cracking Distillation Hydrotreating Liquid Heating Quenching Steam/Catalytic Reforming 7
Table 8: Fluid Heating Process Atmospheres Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Air Heating Distillation Quenching Catalytic/Thermal Cracking Hydrotreating Liquid Heating Steam/Catalytic Reforming Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum Figure 9: Fluid Heating Process Temperatures Air Heating 70 F 1,200 F 968 F 1,382 F Catalytic/Thermal Cracking 1,112 F Distillation Hydrotreating 662 F 1,022 F Liquid Heating 200 F 750 F 8
80 F 300 F Quenching Steam/Catalytic Reforming 900 F 1,830 F Heat Treating Heat treating is the application of thermal energy to change the microstructure of a material. This alteration then changes the material s mechanical properties strength, ductility, hardness, toughness, and elasticity. Heat treating processes include Aluminizing (Hot Dipping), Annealing, Bluing, Carburizing, Decarburizing, Homogenization, Nitriding, Precipitation Hardening, Solution Heat Treating, and Tempering. The equipment and conditions for each of these processes is outlined in the following tables. Figure 10: Computerized heat treating furnace Table 9: Heat Treating Equipment Fluidized bed reactor Aluminizing Annealing Bluing Carburizing/ Recarburizing Decarburizing Homogenization 9
Fluidized bed reactor Nitriding Precipitation Hardening Solution Heat Treating Tempering Table 10: Heat Treating Process Atmospheres Aluminum Copper Glass Magnesium Nickel Steel Titanium Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum Aluminizing Annealing Bluing Carburizing/ Recarburizing Decarburizing Homogenization Nitriding Precipitation Hardening Solution Heat Treating Tempering 10
Figure 11: Heat Treating Process Temperatures Steel: 1,110 F 1,300 F Aluminum: 570 F 770 F Copper: 500 F 1,700 F Glass: 742 F 1,020 F Magnesium: 550 F 850 F Nickel: 1,300 F 2,200 F Steel: 1,350 F 1,650 F Titanium: 1,200 F 1,650 F Steel: 644 F 1,000 F Titanium: 1,920 F Steel: 1,510 F 1,740 F Steel: 1,300 F Copper: 1,425 F 1,950 F Metals: 932 F 950 F Aluminum: 250 F 400 F Copper: 660 F 1,000 F Magnesium: 265 F 480 F Nickel: 800 F 1,600 F Steel: 900 F 1,100 F Titanium: 735 F 1,400 F Aluminizing Annealing Bluing Carburizing Decarburizing Homogenization Nitriding Precipitation Hardening 11
Aluminum: 920 F 1,000 F Copper: 1,400 F 1,830 F Magnesium: 725 F 1,050 F Nickel: 1,800 F 2,150 F Steel: 1,500 F 1,600 F Titanium: 1,400 F 1,940 F Steel: 350 F 1,300 F Solution Heat Treating Tempering Metal Heating In contrast to heat treating, metal heating primarily refers to the heating of metals to establish ideal fabrication conditions in shaping processes. This application of heat increases the malleability of metals to prevent them from fracturing during coldand hot-working processes such as forging, extraction, and rolling. In addition to shaping metals, metal heating is required in coating processes such as galvanization and chemical vapor deposition (CVD). The equipment and conditions for each of these processes is outlined in the following tables. Table 11: Metal Heating Equipment Figure 12: Sheet of metal being heated prior to shaping Fluidized bed reactor CVD Coating Cold- Working Galvanizing Hot-Working 12
Table 12: Metal Heating Process Atmospheres Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Hydrocarbon Oxygen Particle-Free Pressurized Reducing Salt Bath Sulfur-based Vacuum CVD Coating Cold-Working Galvanizing Hot-Working Figure 13: Metal Heating Process Temperatures Metals: 1,470 F 2,010 F Chemical Vapor Deposition Coating Metals: 70 F 450 F Cold-Working Metals: 850 F 1,436 F Aluminum: 500 F 950 F Copper: 1,300 F 1,740 F Steel: 1,300 F 2,250 F Titanium: 1,600 F 1,800 F Galvanizing Hot-Working 13
Metal & Non-Metal Melting Melting is a standard procedure used to convert a material from a solid to a liquid by applying heat (also known as molten ). It is commonly used in the metals industry to convert bulk ingots to finished or semifinished castings. Non-metal melting is also used in the production of glass. Metal and Non-Metal Melting processes include Casting, Enameling, Glass Production, Joining, and Sintering (Powder Metallurgy). The equipment and conditions for each of these processes is outlined in the following tables. Figure 14: Molten metal being poured into mold Table 13: Metal & Non-Metal Melting Equipment Fluidized bed reactor Casting Enameling Glass Production Joining Sintering (Powder Metallurgy) 14
Table 14: Metal & Non-Metal Melting Process Atmospheres Casting Enameling Glass Production Air/Ambient Ammonia Carbon-based Dry steam/air Inert gas Helium Hydrogen Hydrocarbon Oxygen Particle-Free Pressurized Joining Sintering (Powder Metallurgy) Reducing Salt Bath Sulfur-based Vacuum Figure 15: Metal & Non-Metal Melting Process Temperatures Aluminum: 865 F 1,240 F Magnesium: 660 F 1,220 F Steel: 2,600 F 2,800 F Titanium: 3,020 F 3,034 F Casting Aluminum: 1,000 F 1,020 F Steel: 1,450 F 1,550 F Enameling Glass: 2,912 F 4,532 F Glass Production Filler Metals: 361 F 2,260 F Joining Ceramic: 2,000 F 2,700 F Steel: 1,472 F 2,192 F Sintering (Powder Metallurgy) 15