Thermal liner materials

Thermal oxidizers must be built to provide the residence time and temperatures to achieve the desired destruction efficiency (DE). As such, thermal oxidizers are comparatively larger than catalytic oxidizers since their residence time is two to four times greater. Historical designs of thermal oxidizers were comprised of carbon steel for the outer shell and castable refractory or brick as the thermal liner (a refractory is like a cement, which is put on the inside of the rector shell to act as a thermal insulation barrier). Modern units are designed and built using ceramic fiber insulation on the inside, which is a lightweight material, and has a relatively long life. Old refractory would tend to fail over a period of years by attrition of expansion and contraction. 

The body of the injector is heated to ensure the sample is volatilized and inside is an inert glass liner. This glass liner helps minimize any sample decomposition that might occur when thermally labile materials come in contact with hot-metal surfaces. The carrier gas enters behind the glass liner and is thus preheated. The sample is injected into the stream of carrier gas that passes down the center of the tube, a portion passes down the capillary column. 

The use of CMCs as liner material for gas turbines is a key concept to increase efficiency and reduce emissions. Replacement of metallic components by thermally stable ceramics allows reducing the amount of cooling air significantly. This will not only increase overall efficiency but allows lean combustion concepts. Moreover, ceramic components are required for future turbine technologies based on hydrogen combustion. 

Table 10.4 shows the effect of two heat sources on various types of fabric. Woven and nonwoven fabrics of different area densities made from aramid and FBI fibre have been compared in terms of their respective thermal protective performance (TPP) indices and the results are shown in Table 10.5. TPP values are the times for a temperature gradient of 25 °C to be generated across the fabric thickness when exposed to a heat source as defined in ASTM D4108. The higher the TPP value, the better the thermal protective property. The original fabric constructional data were published in imperial units and they have been converted to SI units for consistency. Woven fabrics were designed as the outer shell material in firefighters turnout coats, and the needlefelt, nonwoven fabrics could be considered for use as a backing or thermal liner in thermally protective apparel. This work shows that nonwoven fabrics provide...

The material for the thermal liner as well as the liner-to-nozzle weld is Inconel 600, for which the modulus of elasticity, E, and the yield strength, Sy, are 207 GPa and 240 MPa, respectively. The design stress intensity Sm for the material is 2/3 Sy or 160 MPa. The design fatigue curve for the material is obtained from Reference 2 and is shown in Figure 12.5. This figure is based on an elastic modulus of 180 GPa. The alternating stresses... 

Barker, R.L., Heniford, R.C., 2011. Factors affecting the thermal insulation and abrasion resistance of heat resistant hydro-entangled nonwoven batting materials for use in firefighter turnout suit thermal liner systems. J. Eng. Eibers Fabr. 6(1), 1-10. 

Thermal Insulation. Foamed plastics (qv) are used as thermal insulation for aU types of constmction because of their low heat- and moisture-transmission values. Polystyrene is used either as foamed board or expandable beads. The foam may be faced with a stmctural surfacing material, eg, a kraft liner-board, to form a panel for insulating mobile homes. These foams can dupHcate the appearance of wood and be used as trim. Foams can also be used as backing, for example, on aluminum siding, to provide heat and sound insulation. Foamed beads can be incorporated in concrete to reduce its density and provide some thermal insulation. 

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