Stoving process

Ground coat and cover coal enamel can also be fired together (two-layer-single stoving processes)... 

Bleaching of wool with sulphur dioxide (stoving process)... 

With appropriate optimisation of air flow, heat recovery and oxidation method, it is normally possible to almost eliminate the need for support fuel. In some cases, the use of secondary heat exchange can generate a significant process credit (e.g. in applications where solvent concentrations in the waste gas are high and high temperatures are needed in the paint stoving process). 

Plastisols are used in automotive assembly for lower performance applications, e.g. the bonding of panel reinforcements. An advantage here is that they are capable of bonding oily surfaces some absorb the oil film during cure, reducing the required surface preparation. Also, the adhesive may be formulated such that it cures during the paint-stoving process. 

The ancient process of stoving is stiU occasionally used to bleach wool and silk with sulfur dioxide. In this process, wet fabrics are hung in chambers of burning sulfur or sulfur dioxide gas for at least 8 h. The fabrics are then washed with sodium sulfite to remove excess sulfur dioxide. Fabric so treated may have unpleasant odors, and the original color eventually returns, but the process is simple and inexpensive. 

The carbonization by-products are usually refined, within the coke plant, into commodity chemicals such as elemental sulfur (qv), ammonium sulfate, benzene, toluene, xylene, and naphthalene (qv) (see also Ammonium compounds BTX processing). Subsequent processing of these chemicals produces a host of other chemicals and materials. The COG is a valuable heating fuel used mainly within steel (qv) plants for such purposes as firing blast furnace stoves, soaking furnaces for semifinished steel, annealing furnaces, and lime kilns as well as heating the coke ovens themselves. 

A heat balance for the blast furnace produced by Michard et al. (1967), shows tlrat nearly 80% of the heat generated in tire furnace is used to produce and melt the iron and slag. The gas which emerges from tire first zone is further used to pre-heat the ah injected in the tuyeres in large stoves. The process thus runs at a vety high efficiency, botlr from tire point of view of tire amount of metal and slag produced and from the heat generation and utilization. 

Schwitz-kammer, /. sweating room, sweating stove. -mittel, n. sudorific, diaphoretic, -dl, n. (Petroleum) foots oil, -pulver, n. diaphoretic powder, -roste, /. steam retting, -verfahren, n. sweating process, -wasser, n. condensed moisture, sweat. 

Prior to World War II, only about half of households in the United States had complete indoor plumbing facilities, including hot and cold water. Before indoor plumbing became widespread, water was heated on stoves in pots and pans, a difficult process that meant a lot less hot water was used. 

Non-Metallic Materials Numerous engineering thermoplastics have been commercialised including materials such as polyetherether ketone (PEEK) and polyether sulphate (PES) with much improved thermal/chemical resistance. The usage of FRP equipment has increased, and fluoropolymer lining technology/applications have come of age. Of particular interest is the development of stoved, fluoropolymer coating systems for process industry equipment. 

Paints are specially formulated for one of two processes. In the first, anodic electrodeposition, the article to be painted is made the anode in a d.c. circuit. Cathodic electrodeposition is the reverse operation. The process takes place under carefully controlled conditions in a tank. Current passes through the paint causing it to deposit uniformly over the article in a uniform film whose thickness can be accurately controlled. The paint film is insoluble in water and exhibits remarkable adhesion after stoving. Electrodeposition is widely used to apply primers, e.g. by car manufacturers, and one coat finishes. 

Electrodeposition This method of paint application is basically a dipping process. The paint is water-based and is either an emulsion or a stabilised dispersion. The solids of the paint are usually very low and the viscosity lower than that used in conventional dipping. The workpiece is made one electrode, usually the cathode, in a d.c. circuit and the anode can be either the tank itself or suitably sized electrodes sited to give optimum coating conditions. The current is applied for a few minutes and after withdrawal and draining the article is rinsed with de-ionised water to remove the thin layer of dipped paint. The deposited film is firmly adherent and contains a minimum of water and can be stoved without any flash-off period. This process is used for metal fabrications, notably car bodies. Complete coverage of inaccessible areas can be achieved and the corrosion resistance of the coating is excellent (Fig. 14.1). 

Sanding is carried out at this stage and, after clean-up, the final colour or top-coat is applied. There is some variation in the resin chemistry used. Alkyds crosslinked with melamine-formaldehyde are widely used for non-metallic pigmentation. Metallics are usually based on acrylics for better durability. The acrylic may be thermoset with melamine-formaldehyde or a thermoplastic lacquer (plasticised copolymer of methyl methacrylate). A thickness of about 50ftm is applied and stoved for 20 min at 130°C (lacquers receive a bake-sand-bake process for a smoother appearance). 

Again, we use a condensed form of the seven-step strategy. A temperature change signals a heat flow. In this example, an increase in the temperature of the aluminum pan means that heat flows from the surroundings (including the stove) to the pan, which represents the system. As in Example, a diagram summarizes the process. 

Figure 6-13 shows three different paths for the combustion reaction of methane. One path, indicated with the blue arrow, is the path that might occur when natural gas bums on a stove burner. As CH4 and O2 combine in a flame, all sorts of chemical species can form, including OH, CH3 O, and so on. This is not a convenient path for calculating the energy change for the net reaction, because the process involves many steps and several unstable chemical species. 

In our world, most chemical processes occur in contact with the Earth s atmosphere at a virtually constant pressure. For example, plants convert carbon dioxide and water into complex molecules animals digest food water heaters and stoves bum fiiel and mnning water dissolves minerals from the soil. All these processes involve energy changes at constant pressure. Nearly all aqueous-solution chemistry also occurs at constant pressure. Thus, the heat flow measured using constant-pressure calorimetry, gp, closely approximates heat flows in many real-world processes. As we saw in the previous section, we cannot equate this heat flow to A because work may be involved. We can, however, identify a new thermod mamic function that we can use without having to calculate work. Before doing this, we need to describe one type of work involved in constant-pressure processes. 

C06-0043. In each of the following processes, energy is transformed from one type to another. Identify what type of energy is consumed and what type is produced, (a) Methane bums on the element of a stove, (b) An elevator carries passengers from the ground floor to the fourth floor, (c) A firefly produces light on a summer evening. 

C14-0046. Without doing any calculations, determine the signs of AS for the system, for the surroundings, and for the overall process in each of the following (a) Water boils in a teakettle on a hot stove, (b) Ice in an ice cube tray, left on a counter top, melts, (c) A cup of coffee is reheated in a microwave oven. 

Iron making. Molten iron is produced for steel making in blast furnaces using coke, iron ore, and limestone. Blast furnace operations use water for noncontact cooling of the furnace, stoves, and ancillary facilities and to clean and cool the furnace top gases. Other water, such as floor drains and drip legs, contribute a lesser portion of the process wastewaters. 

---