Pyrolysis equipment

The purpose of the study was to determine the optimum conditions of operation of pyrolysis equipment by the combined solution of equations relating to the technological and economic analysis of the process. The material considered was poly(methyl methacrylate) one of the most popular types of plastic waste. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. 

The most common type of commercial pyrolysis equipment is the direct fired tubular heater in which the reacting material flows through several tubes connected in series. The tubes receive thermal energy by being immersed in an oil or gas furnace. The pyrolysis products are cooled rapidly after leaving the furnace and enter the separation train. Constraints on materials of construction limit the maximum temperature of the tubes to 1500 °F. Thus the effluent from the tubes should be restricted to temperatures of 1475 °F or less. You may presume that all reactor tubes and return bends are exposed to a thermal flux of 10,000 BTU/... 

One of the most common causes of non-reproducible results is contamination of sample or pyrolysis equipment with unidentified foreign material such as plasticizers contained in solvents used for MWL preparation and from plastic bottles used to store samples. 

The literature review of microwave-assisted or induced pyrolysis of plastics follows. In this section special attention is paid to the reactor configurations used, comparing them with the configurations found on more conventional pyrolysis equipment. The most important findings produced from this research are presented, including product yield, characteristics and composition. An analysis is presented to assess whether in any example there is evidence for nonthermal microwave effects promoting the pyrolytic reactions. 

As mentioned above, the main difference between microwave and conventional pyrolysis is the initial sonrce of thermal energy and the way this is transferred to the plastic. Nonetheless, there are other differences, particularly when microwave pyrolysis is compared with flnidized-bed pyrolysis equipment in the latter, the primary reaction prodncts are carried ont of the reactor by a hot gas stream which enables these products to take part in secondary and tertiary reactions. On the other hand, in microwave pyrolysis, once the pyrolytic prodncts leave the carbon bed, they stop receiving heat by conduction from the hot carbon and come in contact with a relatively cold carrier gas. This has an important effect in the nnmber of consecntive reactions occnrring and therefore, on the natnre of the prodncts, as is shown in Section 3.2.2. 

Table 21.2 shows various results for product (phases) yields for the degradation of PE at 500 and 600°C along with the results obtained using microwave pyrolysis. As can be seen in the table, in the latter case the increase in temperature caused little difference in the yields of the products. These results, which seem to contradict most previous findings, may be explained by the configuration of the microwave pyrolysis equipment. 

A lthough coke formation is always of importance during pyrolysis processes that are used for production of ethylene and other valuable olefins, diolefins, aromatics, etc., relatively little is known about the factors affecting such coke formation. It has been found that operating conditions, feedstock, pyrolysis equipment, and materials of construction and pretreatments of the inner walls of the pyrolysis tubes all affect the production of coke. General rules that have been devised empirically at one plant for minimizing coke formation are sometimes different than those for another plant. It can be concluded that there is relatively little understanding of, or at least little application of, fundamentals to commercial units. 

Pyrolysis Equipment and Procedure. The decant oil samples were pyrolyzed using a horizontal tube furnace equipped with an electronic temperature controller. The samples (1-2 g) were weighed into stainless steel tubes (6 mm o.d., 200 mm long), which were then flushed with nitrogen and sealed with Swagelok end caps. It was important that the sample holder be capable of complete disassembly to facilitate the recovery of the products of pyrolysis, which were largely viscous tars and coke. It had been found previously with a more elaborate flowthrough reactor system, that not all the carbonaceous reaction products could be recovered readily. 

Pyrolysis-direct chemical ionization mass spectrometry ( r-DCI-MS) was recently introduced as a pyrolysis technique for the characterization of complex macromolecular samples and for the analysis of biopolymers. This technique does not require special pyrolysis equipment and can be performed with an instrument which is equipped with a chemical ionization source and a standard DCI probe, which consists of an extended wire used to introduce the sample material directly into the chemical ionization plasma. An important characteristic of this technique is the pyrolysis... 

B) Pyrolysis Equipment. The pyrolysis process is also relevent. In that case, the operation aims at utilizing waste by producing a residual char. A specific combustible is obtained (active char or charcoal, refractory ashes...) at the rate of approximately 25 % of the initial weight. 

Figure 5.12 Schematic diagram of spray pyrolysis equipment [103].

In the interest of efficiency, autosamplers have become increasingly important in analytical laboratories. Autosampling systems are now available for all three types of pyrolysis equipment furnaces. Curie point, and resistively heated filament... 

Since this chapter was first published 10 years ago, a very noticeable tendency in pyrolysis research can be observed fewer investigators are using Py-GC/FID as a hngerprinting technique, and more and more use Py-GC/MS as a method of choice for both hngerprinting and decoding the structure of aualyzed compounds. This tendency could be explained by substantial improvements in MS detectors, enrichment of available MS libraries of compounds, and appearance of reasonably priced GC/MS instrumentation. To be fair, it should be mentioned that the price range of pyrolysis equipment for the last 10 years has risen quite substantially, in line with quality and sophisticahon. 

In addition to the difficulties arising from the samples of art and archaeological materials, there are those posed by pyrolysis equipment. 

Voorhees et al. described an environmental application that is not a pyrolysis application per se, but rather an environmental application of pyrolysis equipment that seemed too clever not to mention here. 

Earlier pyrolysis equipment tended to be somewhat complex in design and operation. Thus, Cox and Ellis Mescribed a micro-reactor pyrolyser which they applied to large numbers of polymers. Temperatures increases of 700 - 1000°C were used in order to completely pyrolyse O.lg samples of the polymers. The pyrolysis products were collected for 15 min then swept onto a gas chromatographic column equipped with a flame ionization detector. This type of equipment has now been displaced by the more recently described equipment as discussed later. 

The gas product from pyrolysis is typically composed of a mixture of CO2 (9-55 vol. %), CO (16-51 vol. %), H2 (2-43 vol. %), CH (4-11 vol. %) and small amounts of higher hydrocarbons. The gases are usually present with N2 introduced to the reactor for creating an inert atmosphere during the pyrolysis equipment. The CO2 and N2 provide no energy value to the gas product in combustion, although the other gases are flammable and provide... 

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