33 Breeching and Ducting between convection section and stack Refractory

33 breeching and ducting between convection section

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3.3 Breeching and Ducting (between convection section and stack): Refractory linings must provide thermal resistance, mechanical integrity, and protect against metal shell corrosion. Although the breech and ducting linings are exposed to relatively low temperature during normal operation, they also provide fire protection if a tube ruptures in the radiant or convection section. 3.4 Stacks : Refractory linings in the stack must provide thermal resistance, mechanical integrity, and protect against metal shell corrosion. 3.5 Burner Block : Burner block must insulate the burner housing while not being adversely affected by high temperature or thermal cycling related to startup and shutdown. Block must resist flame impingement and corrosive impurities. 3.6 Gravity Walls : Free standing walls inside fired heaters to provide physical separation of process areas within the furnace, typically between radiant sections operating at different temperatures or between radiant and convection sections. In radiant sections the walls also provide surfaces of radiation to improve heat transfer to the tubes. 4.0 Critical performance factors affecting refractory lining selection: 4.1 Design Temperature is a temperature used to make refractory selections. It is the calculated hot face or interface temperature plus the required design margin of 165°C minimum (300°F). Some minimum refractory design temperatures based on typical hot face temperatures in furnace locations are the following: 4.1.1 Burner area: 1650°C (3000°F) 4.1.2 Target walls with flame impingement on one or both sides: 1540°C (2800°F) 4.1.3 Floor: 1370°C (2500°F) 4.1.4 Radiant and shielded section: 980°C (1800°F) 4.1.5 Convection section: 980°C (1800°F) 4.1.6 Breeching and Ducting: 510°C (950°F) 4.1.7 Air preheating system: 510°C (950°F) 4.1.8 Access doors shall be protected from radiation by a refractory system of at least the same temperature rating and thermal resistance as the adjacent wall lining. 4.2 Maximum Use Temperature : Maximum continuous temperature to which a refractory may be exposed without excessive shrinkage or mechanical breakdown. It is also sometimes referred to as the “recommended use limit.” or continuous use temperature.
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Refractory Lining and Burner Brick Requirements API 560 Revision Date: May 3, 2011 5 4.3 Hot Face Temperature is the flue gas or the heated combustion air temperature at the hot face of the lining. This is the temperature used for thermal calculations for operating cold face temperature and heat loss.. 4.4 Interface Temperature is the calculated temperature at the intersection of each different layer of refractory material if multilayer or multi component refractory construction is used. 4.5 Cold Face Temperature is the temperature at the casing calculated using the thermal resistance of the lining and hot face temperature. The lining is designed to meet specified thermal efficiency of the equipment and/or personnel protection requirements.
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  • Spring '18
  • Furnace, Refractory, Refractory materials, Owner/Fabricator

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