FIRING TEMPERATURE

Eady pottery is rather simple, having Httie surface decoration. Pyrotechnology was comparatively undeveloped and pottery was fired at relatively low temperatures. As kilns became available and were in turn further perfected, higher firing temperatures became attainable, resulting in harder, stronger wares. 

Continual use of decabromidiphenyl oxide has been placed ia question based on the discovery that under certain laboratory conditions brominated dibenzo- -dioxias are generated (63). The condition most often employed ia such studies is pyrolysis of milligram-scale samples at 600°C. This temperature is higher than polymer processiag conditions and lower than fire temperatures, ie, the conditions are not representative of actual conditions to which flame-retardant polymers are exposed. 

Uses. Lithium fluoride is used primarily in the ceramic industry to reduce firing temperatures and improve resistance to thermal shock, abrasion, and acid attack (see Ceramics). Another use of LiF is in flux compositions with other fluorides, chlorides, and borates for metal joining (17) (see Solders). 

To achieve the maximum coating opacity the opacifter particle size should be between 0.2 and 0.3 ]lni. A good opacifter should not be soluble in the vitreous system, should have a refractive index substantially different from the refractive index of the system, should be inexpensive, easily milled to a submicrometer particle size, and thermally stable at the film s firing temperature. 

Hz unit. To accommodate the higher firing temperatures and mass flows, these units employ advanced alloys, coatings, and modified cooling schemes. Many features of these units were derived from aircraft engine designs. 

Wood in its untreated form has good resistance or endurance to fire penetration when used in thick sections for walls, doors, floors, ceilings, beams, and roofs. This endurance is due to low thermal conductivity, which reduces the rate at which heat is transmitted to the interior. Typically, when the fire temperature at the surface of softwood is 870—980°C, the inner char 2one temperature is - 290° C, and 6 mm further inward, the temperature is 180°C or less. The penetration rate of this char line is mm/min, depending on the species, moisture content, and density (45,46). Owing to this slow... 

The product gas after cleanup consists of primarily CO and H2. Combustion of coal gas in high firing-temperature gas turbines converts virtually all of the CO to CO2, and gas turbine exhaust is expected to contain no more than 10 ppm CO when operating at design conditions. Carbon monoxide emissions from a CGCC plant are thus expected to be around one-tenth those of a modem coal-fired plant equipped with low NO burners. 

The resistance of these materials to firing temperature is definitely limited. They can be fired to about 1000°C. Hence, they are limited to use in porcelain enamels and in low firing artware gla2es. 

Enamel firing temperature is dictated by the coating composition, metal thickness, and the type of metal used. Enamels for aluminum are fired at... 

The typical amounts of sodium and vanadium in the fuel should be less than 1 ppm. Figure 29-42 shows the effect of sodium and vanadium on the life of the blade and on the combustor life. Figure 29-43 shows the reduction in firing temperature required to maintain design life (hrs) of a typical turbine (IN718) blade due to sodium and vanadium in the fuel. 

FIG. 29-43 Firing temperature reduction needed to offset IN 718 corrosion by sodium and vanadium. 

The new marketplace of energy conversion will have many new and novel concepts in combined cycle power plants. Figure 1-1 shows the heat rates of these plants, present and future, and Figure 1-2 shows the efficiencies of the same plants. The plants referenced are the Simple Cycle Gas Turbine (SCGT) with firing temperatures of 2400 °F (1315 °C), Recuperative Gas Turbine (RGT), the Steam Turbine Plant (ST), the Combined Cycle Power Plant (CCPP), and the Advanced Combined Cycle Power Plants (ACCP) such as combined cycle power plants using Advanced Gas Turbine Cycles, and finally the ITybrid Power Plants (HPP). 

Figures 1-3 and 1-4 show the growth of the Pressure Ratio and Firing Temperature. The growth of both the Pressure Ratio and Firing Temperature...

The increase in pressure ratio increases the gas turbine thermal efficiency when accompanied with the increase in turbine firing temperature. Figure 1 -5 shows the effect on the overall cycle efficiency of the increasing pressure ratio and the firing temperature. The increase in the pressure ratio increases the overall efficiency at a given temperature, however increasing the pressure... 

The effeet of firing temperature is very predominant—for every 100 °F (55.5 °C) inerease in temperature, the work output inereases approximately 10% and gives about a 1- % inerease in effieieney. Higher-pressure ratios... 

Reliability of a plant depends on many parameters, sueh as the type of fuel, the preventive maintenanee programs, the operating mode, the eontrol systems, and the firing temperatures. 

The latest frame type units introdueed are 480 MW units using steam eooling in the eombined eyele mode, enabling the firing temperatures to reaeh 2600 °F (1427 °C). This enables effieieney in the eombined eyele mode to reaeh 60% plus. 

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