Pyrolysis temperature optimum

A report on the continuous flash pyrolysis of biomass at atmospheric pressure to produce Hquids iadicates that pyrolysis temperatures must be optimized to maximize Hquid yields (36). It has been found that a sharp maximum ia the Hquid yields vs temperature curves exist and that the yields drop off sharply on both sides of this maximum. Pure ceUulose has been found to have an optimum temperature for Hquids at 500°C, while the wheat straw and wood species tested have optimum temperatures at 600°C and 500°C, respectively. Organic Hquid yields were of the order of 65 wt % of the dry biomass fed, but contained relatively large quantities of organic acids. 

The optimum pyrolysis temperature is 395°C to give a recovery ratio of 0.97 (i.e. 1000 kg polystyrene will yield 970 L liquid monomer) and 5 to 10% char residue. Fuel made from polystyrene feedstock will be high in aromatic character and have an energy content of 50 MJ/kg and a pour point of —67°C. However the flash point is only 26°C and the cetane rating only 12.6. The fuel needs to be blended with polyolefin-derived diesel or regular diesel in order to upgrade the flash point and cetane rating to within specification. 

Pyrolysis temperature has the greatest influence on the quality and quantity of pyrolysis liquids. Earlier studies indicate the optimum temperature for a high oil yield between 475 and 500 °C [6] [15], Table I shows the experimental conditions for three different feedstock investigated by lab, scale pyrolysis (glass-pyrolysis-reactor). The experimental conditions for the different feedstock pyrolysed with the PDU-scale equipment are presented in Table 2. 

The purpose of this study is to maximize the fraction of arsenic in wood charcoal while minimizing mass reduction of the bio-oil. Lab-scale pyrolysis was conducted in order to determine mass balances of yield and percentage of arsenic over the total system The experimental set-up was built to examine the influence of process parameters such as pyrolysis temperature and total pyrolysis time. The optimum combination of temperature and total pyrolysis time, at which the amount of arsenic retained in the wood charcoal is maximized and that in oil is minimized, was tried to be found. 

In the present work no attempt was made to optimise the magnetic separation conditions rather the emphasis was on sulphur rejection as a function of pyrolysis temperature, to give information on the optimum pyrolysis temperature for separation. 

In order to determine Bi by GF AAS under stabilized temperature platform furnace (STPF) conditions using the Pd-Mg modifier, a pyrolysis temperature of 1200 °C must be applied (Hiltenkamp and Werth 1988). The optimum atomization temperature under these conditions is 1900 °C the characteristic mass with Zeeman effect background correction (BC) is 28 pg, while in a non-Zeeman instrument it is about 20 pg. 

Pyrolysis and atomization curves of manganese are shown in Fig. 2. The pyrolysis curve was obtained using 2300°C as the atomization temperature. The selected pyrolysis temperature for Mn in THFA is about 1600°C. Using this pyrolysis temperature, the optimum atomization temperature corresponds to 2100°C. These pyrolysis and atomization temperatures do not correspond to the THGA suggested temperatures [21], as the furnace design is different and the rate of the vaporization process is also different. Some loss on manganese is observed above 2100 C, due to the volatility of the atomic species at hi temperature. 

FIG. 5. Pyrolysis-atomization curves for electrothermal A AS. A = integrated absorbance signal plotted against applied pyrolysis temperature (pyrolysis curve) B = integrated absorbance signal plotted against atomization temperature (atomization curve). 1 = maximum pyrolysis temperature 2 = lowest temperature of complete volatilization 3 = appearance temperature 4 — optimum atomization temperature. (From Ref. 23 by permission.)... 

Initially, non-polar stationary phases only (of the methyl silicone type) were used in high-temperature GC, and cross-linking and chemical-bonding improved the properties of the columns appreciably. More polar bonded phases, consisting of phenylmethyl silicones, later came into use and are available commercially. At present, these have a temperature limit of about 360 C, and while this will no doubt be improved, the ultimate limit may depend on the pyrolysis temperature of triacylglycerols. The optimum thickness of the liquid film for high-temperature GC is about 0.1 to 0.12 o.m. 

Figure 8.13 Typical pyrolysis curve for GF AAS the integrated absorbance obtained at the optimum atomization temperature is plotted against the pyrolysis temperature...

Optimum pyrolysis temperature to measure its pyrogram. Furthermore, by use of the average mass spectrum data search mentioned above, you could often make rapid identification of the polymeric materials. 

In developing a systematic scheme of polymer identification, pyrolysis conditions must be such that all polymers degrade rapidly. However, at temperatures above 1000 °C the pyrograms will also be less suitable for identification, since secondary reactions become predominant, leading to increasing amounts of simple molecules such as carbon dioxide, acetylene, ethylene or benzene which gives less characteristic patterns than those observed for monomers or primary degradation products. Pyrolysis temperatures between 500 and 800 C (optimum 610 °C) for 10 seconds are recommended. 

The results of research into the fluidised bed pyrolysis of plastic wastes are reported, with reference to determining the optimum process conditions for the process with respect to the reactor behaviour. The study investigates the effects of process variables such as bed temperature, polymer feed rate, bed hold-up, fluidising velocity, and size of inert material. Findings illustrate the importance of the knowledge of the hydrodynamics of the fluidised bed and of the interactions between bed and polymer particles in the design and operation of the reactor. 15 refs. 

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