Furnace pyrolysis

The separation train of the plant is designed to recover important constituents present in the furnace effluent. The modem olefin plant must be designed to accommodate various feedstocks, ie, it usually is designed for feedstock flexibiUty in both the pyrolysis furnaces and the separation system (52). For example, a plant may crack feedstocks ranging from ethane to naphtha or naphtha to gas oils. 

Figure 3.24 shows the process flowsheet for an ethylene/ethylbenzene plant, Gas oil is cracked with steam in a pyrolysis furnace to form ethylene, low BTU gases, hexane, heptane, and heavier hydrocarbons. The ethylene is then reacted with benzene to form ethylbenzene (Stanley and El-Halwagi, 1995). Two wastewater streams are formed R ... 

A typical ethane cracker has several identical pyrolysis furnaces in which fresh ethane feed and recycled ethane are cracked with steam as a diluent. Figure 3-12 is a block diagram for ethylene from ethane. The outlet temperature is usually in the 800°C range. The furnace effluent is quenched in a heat exchanger and further cooled by direct contact in a water quench tower where steam is condensed and recycled to the pyrolysis furnace. After the cracked gas is treated to remove acid gases, hydrogen and methane are separated from the pyrolysis products in the demethanizer. The effluent is then treated to remove acetylene, and ethylene is separated from ethane and heavier in the ethylene fractionator. The bottom fraction is separated in the deethanizer into ethane and fraction. Ethane is then recycled to the pyrolysis furnace. 

An olefin plant that uses liquid feeds requires an additional pyrolysis furnace, an effluent quench exchanger, and a primary fractionator for fuel oil separation. 

Ethylene dichloride from this step is comhined with that produced from the chlorination of ethylene and introduced to the pyrolysis furnace. 

Figure 7-5. The European Vinyls Corporation process for producing vinyl chlo-rlde " (1) chlorination section, (2) oxychlorination reactor, (3) steam stripping and caustic treatment of water effluent, (4) EDC distillation, (5) pyrolysis furnace, (6,7,8) VCM and EDC separation, (10) by-product reactor.

GC-TEA Analysis. A Bendix model 2200 GC and Thermo Electron model 502 TEA were used. The GC injector temperature was 210 C. The TEA pyrolysis furnace was operated at 450 C and the cold trap was held at -150 C in isopentane slush. Oxygen flow to the ozonator was 20 cc/min and indicated pressure was 1.5 torr at a helium flow rate of 20 cc/min. TEA output was processed by a digital integrator (Spectra Physics System I). 

In the Antek Fluoride Analyzer, a pyrolysis furnace is combined with an ion-specific electrode cell (ISE). Table 8.9 compares this specific analyser to a conventional combustion bomb. 

The basic construction consists of a rectangular or cylindrical steel chamber, lined with refractory bricks. Tubes are arranged around the wall, in either horizontal or vertical banks. The fluid to be heated flows through the tubes. Typical layouts are shown in Figure 12.69a, b and c. A more detailed diagram of a pyrolysis furnace is given in Figure 12.70. 

Figure 12.70. (Foster Wheeler) Multi-zoned pyrolysis furnace...

Both pipe sizes give reactors that are satisfactory from the standpoint of pressure drop and effluent temperature. Although the 4-in. reactor must be longer to achieve the desired conversion, it requires significantly less volume, and this is an important consideration in the design of a pyrolysis furnace. The 6-in. pipe has... 

The process of dehydrogenation of EB is shown in Figure 8-6. The process is similar to operations in an olefins plant in that dehydrogenation is done by mixing the feed with steam and cracking it in pyrolysis furnaces. However, the cracking products are more limited, primarily because of the use of a catalyst, iron oxide. 

VC is made by cracking EDC in a pyrolysis furnace much like that in an ethylene plant. Thats one of the three reactions, shown in Figure 9—1, involved in the process. The other two have formidable names—chlorination and oxychlorination—but simple enough reactions—the addition of chlorine and the addition of oxygen and chlorine. What is a little complicated is the fact that the hydrogen chloride used to make the EDC in the first reaction comes from cracking EDC in the second. Sounds like a closed circle until you peel it back and examine it. 

Figure 9—2 shows the plant with its three reactors. The pyrolysis furnace is in the middle. At the top of the figure, the basic feeds, to the plant are shown—ethylene, chlorine, and oxygen. Ethylene and chlorine alone are sufficient to make EDC via the route on the left. The operation, call it Reaction One like Figure 9-1 does, takes place in the vapor phase in a reactor with a fixed catalyst bed of ferric (iron) chloride at only 100—125°F. A cleanup column fractionates out the small amount of by-products that get formed, leaving an EDC stream of 96—98% purity. 

For Reaction Two, the purified EDC is passed through a dryer to remove water, then fed to a pyrolysis unit. The difference between EDC pyrolysis furnaces and those used for ethylene is the use of a catalyst. 

The study of retained NMP in the films was conducted using a Du Pont DP-102 Mass Spectrometer. These films were heated in a tube-type pyrolysis furnace and the amount of NMP given off detected and quantitized against a calibration curve. Pyrolysis conditions were 750°Cx2 seconds with quantitation done on mass 99 molecular ion. A CDS-190 Pyroprobe was used for the pyrolysis study. 

Dolan and Hall [148] have described a Coulson electrolytic conductivity detector of enhanced sensitivity for the gas chromatographic determination of chlorinated insecticides in the presence of PCBs. The detector was modified by the replacement of the silicone-rubber septum and stainless steel fitting at the exit of the pyrolysis furnace with PTFE fitting, by the reduction in diameter of the PTFE transfer tube, and by the... 

Transfer-line exchanger (TLX or TLE) Primary heat exchanger adjacent to the pyrolysis furnace. 

Multiple pyrolysis furnaces are employed in an industrial pyrolysis plant in order to maintain reasonably constant production levels, even when one furnace is shut down for decoking or maintenance repairs. The coils or tubes in a furnace or the transfer-line exchanger must... 

In the analysis of nitroaromatic explosives, TEA is similar to the systems used for nitrosamines except for the fact that temperatures must be higher. Several papers have reported that the temperature of the TEA pyrolysis furnace can affect the selectivity of the detector. A study carried out by Douse [34] to detect traces of several explosives at the low nanogram level revealed that the chromatograms obtained by GC-TEA for both pure compounds and spiked handswabs clearly showed the superior selectivity of TEA in reducing the temperature from 800 to 700°C. Reduction from 700 to 550°C further... 

Traditionally, olefins in the United States have been produced from light hydrocarbon pyrolysis. Earlier publications on computer simulation and control of pyrolysis reactors were addressed primarily to pyrolysis furnaces using ethane, propane and butane as feedstocks (1,2,3). 

Figure 2. Schematic diagram of a typical pyrolysis furnace...

Apparatus Use the Dohrmann Microcoulometric Titrating System (MCTS-30), or equivalent (shown in Fig. 30), unless otherwise specified in an individual monograph. It consists of a constant rate injector, A, a pyrolysis furnace, B, a quartz pyrolysis tube, C, a granular-tin scrubber, D, a titration cell, E, and a microcoulometer with a digital readout, F. 

Pyrolysis Furnace The sample should be pyrolyzed in an electric furnace having at least two separate and independently controlled temperature zones, the first being an inlet section that can maintain a temperature sufficient to volatilize all the organic sample. The second zone is a pyrolysis section that can maintain a temperature sufficient to pyrolyze the organic matrix and oxidize all the organically bound sulfur. A third outlet temperature zone is optional. 

Feedstocks For either gaseous (ethane/propane) or liquid (C4/naphtha/ gasoil) feeds, this technology is based on Technip s proprietary Pyrolysis Furnaces and progressive separation. This method allows producing olefins at low energy consumption with particularly low environmental impact. 

The SCORE pyrolysis furnace portfolio includes a range of designs to satisfy any operating company requirements in terms of feedstock... 

The pyrolysis furnace effluent is processed for heat and product recovery in an efficient, low-cost recovery section. The recovery section design can be optimized for specific applications and/or selected based on operating company preferences. Flow schemes based on demethanizer first, deethanizer first and depropanizer first configurations are available for particular applications. Shown above is the depropanizer first scheme, which is primarily applicable to liquid crackers. 

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