Process furnace coil

Process Furnace Coil Overpressure - The coil of any furnace where the process flow can be stopped by inadvertent closure of a valve in the furnace... 

The second conversion of GS to (GSi)r will be Case 4 of Table 5-10, the two-surface-zone enclosure with computation simphfied by assuming that the direct-view fac tor from any spot to a surface equals the fraction of the whole enclosure that the surface occupies (the speckled-furnace model). This case can be considered an ideahzation of many processing furnaces such as distilling and cracking coil furnaces, with parts of the enclosure tube-covered and part left refrac-toiy. (But the refractory under the tubes is not to be classified as part of the refractory zone.) Again, one starts with substitution into Eq. (5-173) of the terms GSi, GS, and S Si from Table 5-10, Case 4, with all terms first converted to their gray-phis-clear form. To indicate the procedure, one of the components, S Si, wil be formulated. 

A Oil processing furnaces radiant section of oil tube stills and cracking coils it 0.1 < Deff < 1.0... 

The process specifications on raw material speed through furnaces coils imposed the use of two or four parallel passes, e.g. the fumaees from the atmospherie distillation unit, vacuum distillation unit, catalytic reforming unit, coker unit, catalytic cracking unit. The conventional control structure of radiant section for a typical tubular furnace from the atmospheric distillation unit (output capacity 3.5 Mt/year) is presented in figure 1 [1]. Because the conventional temperature control system only controls one outlet temperature or in the best case the temperature of the mixing point, in current operations there are several situations [1, 2, 3] ... 

SCC and environmental embrittlement are the most insidious forms of failure that can be experienced by process equipment, because they tend to strike without warning. There is no noticeable yielding or bulging of the component, there is no measurable metal loss, and through-thickness cracks can form in as little as 1 to 2 h after initial exposure to a crack-inducing environment. For example, cracking throughout an entire furnace coil occurred within 1 h after exposure to air and the resultant formation of polythionic acids. 

High process temperatures generally not achievable by other means are possible when induction heating of a graphite susceptor is combined with the use of low conductivity high temperature insulation such as flake carbon interposed between the coil and the susceptor. Temperatures of 3000°C are routine for both batch or continuous production. Processes include purification, graphitization, chemical vapor deposition, or carbon vapor deposition to produce components for the aircraft and defense industry. Figure 7 illustrates a furnace suitable for the production of aerospace brake components in a batch operation. 

The materials of constmction of the radiant coil are highly heat-resistant steel alloys, such as Sicromal containing 25% Cr, 20% Ni, and 2% Si. Triethyi phosphate [78-40-0] catalyst is injected into the acetic acid vapor. Ammonia [7664-41-7] is added to the gas mixture leaving the furnace to neutralize the catalyst and thus prevent ketene and water from recombining. The cmde ketene obtained from this process contains water, acetic acid, acetic anhydride, and 7 vol % other gases (mainly carbon monoxide [630-08-0][124-38-9] ethylene /74-< 3 -/7, and methane /74-< 2-<7/). The gas mixture is chilled to less than 100°C to remove water, unconverted acetic acid, and the acetic anhydride formed as a Hquid phase (52,53). 

Fired heaters differ from other indirect-fired processing equipment in that the process stream is heated by passage through a coil or tubebank enclosed in a furnace. Fired heaters are classified by function and by coil design. 

PYROCAT A steam cracking process for converting petroleum into light olefins in which a catalyst is deposited on the walls of the heat-exchanger coils in the cracking furnace. The... 

The term channel induction furnace is applied to those in which the energy for the process is produced in a channel of molten metal that forms the secondary circuit of an iron core transformer. The primary circuit consists of a copper coil which also encircles the core. This arrangement is quite similar to that used in a utility transformer. Metal is heated within the loop by the passage of electric current and circulates to the hearth above to overcome the thermal losses of the furnace and provide power to melt additional metal as it is added. Figure 9 illustrates the simplest configuration of a single-channel induction melting furnace. Multiple inductors are also used for applications where additional power is required or increased reliability is necessary for continuous operation (11). 

Furnace Simulation. The purpose of this example is to demonstrate the capability of the PF60 system to predict yield structure and the tubeskin temperature in commercial operating furnaces. Table II summarizes the data from a commercial reactor processing primarily propane as feedstock. At the time the data were taken, the furnace had been on stream less than four days and hence an unfouled radiant coil condition could be assumed. The yields were recorded by on-line chromatographs. The tubeskin temperatures were measured in 15 locations by calibrated infrared pyrometers. 

---