Solid pyrolysis

CNTs can also be produced by diffusion flame synthesis, electrolysis, use of solar energy, heat treatment of a polymer, and low temperature solid pyrolysis. In flame synthesis, combustion of a portion of the hydrocarbon gas provides the elevated temperature required, with the remaining fuel conveniently serving as the required hydrocarbon reagent. Hence, the flame constitutes an efficient source of both energy and hydrocarbon raw material. Combustion synthesis has been shown to be scalable for a high volume commercial production. 

The second step is an autothermal gasification of the pyrolysis gas and the solid pyrolysis char at temperatures above 800°C after partial combustion with air or oxygen. The pyrolysis char carries the whole ash and must be separated from the bed material prior to gasification. Straw char is a rather brittle material and is easily crushed to a fine powder, which gasifies faster. After a relatively fast pyrolysis step the pyrolysis gas contains > 50% of the energy. 

After the pre-treatment process the solid pyrolysis residues are separated from the energy-rich pyrolysis gas within a hot gas filtration unit. The gas is then used as rebum fuel. 

Investigations on the behaviour of volatile and ash components have been carried out. The solid pyrolysis residues of several fuels have been analysed for their main ash composition and their devolatilisation. Increasing reaction temperatures result in a higher devolatilisation for all fuels. E g. straw shows a devolatilisation of approx. 80 above 600 °C pyrolysis temperature. But already at low pyrolysis tenqreratures of 400 °C a rather high devolatilisation of about 70 % can be reached. Other biofuel show a similar behaviour on ash and water free basis. Focusing the devolatilisation efficiency high temperatures in the pyrolysis process give best results, but also pyrolysis at low temperatures yields in sufficient devolatilisation rates. 

Steady-State Conditions During Solids Pyrolysis... 

Figure 3 shows the XRD patterns of the solid pyrolysis products of the citric acld/ethylene glycol precursor after extended heating In oxygen at different temperatures from 500 - 960 0. From these results, it Is apparent that a mixture of CuO, 20 and BaCO Is... 

Euxylophoricine D (88) is a white solid. Pyrolysis of the trifluoroacetate of (91) gives (88), identical in all respects with the natural product. 

Composition of Solid Pyrolysis Products of Hf-Containing Polymers... 

Wynne-Jones and Marshfound somewhat similar results with a number of carbons made by pyrolysis of eight organic polymers at a series of temperatures. The isotherms of Nj at 77 K and of COj at 195 K were measured, and the apparent surface area calculated by the usual BET procedure. (Owing to the microporous nature of the solids, these figures for area will be roughly proportional to the uptake at saturation and therefore... 

Table 15. Product Yields from Pyrolysis of Municipal Solid Waste Organics ...

S. B. Alpert and co-workers. Pyrolysis of Solid Wastes A Technical andEconomic Assessment, NTIS PB 218—231, SRI, Menlo Park, Calif., Sept. 1972. 

Fig. 2. Overall schematic of solid fuel combustion (1). Reaction sequence is A, heating and drying B, solid particle pyrolysis C, oxidation and D, post-combustion. In the oxidation sequence, left and center comprise the gas-phase region, tight is the gas—solids region. Noncondensible volatiles include CO, CO2, CH4, NH, H2O condensible volatiles are C-6—C-20 compounds oxidation products are CO2, H2O, O2, N2, NO, gaseous organic compounds are CO, hydrocarbons, and polyaromatic hydrocarbons (PAHs) and particulates are inerts, condensation products, and solid carbon products.

Heat is transferred by direct contact with solids that have been preheated by combustion gases. The process is a cycle of alternate heating and reactingperiods. The Wulf process for acetylene by pyrolysis of natural gas utilizes a heated brick checker work on a 4-min cycle of heating and reacting. The temperature play is 15°C (59°F), peak temperature is 1,200°C (2,192°F), residence time is 0.1 s of wmich 0.03 s is near the peak (Faith, Keyes, and Clark, Industrial Chemicals, vol. 27, Wiley, 1975). 

Combustion is the rapid exothermic oxidation of combustible elements in fuel. Incineration is complete combustion. Classical pyrolysis is the destructive distillation, reduction, or thermal cracking and condensation of organic matter under heat and/or pressure in the absence of oxygen. Partial pyrolysis, or starved-air combustion, is incomplete combustion and occurs when insufficient oxygen is provided to satisfy the combustion requirements. The basic elements of each process are shown on Figure 27. Combustion of wastewater solids, a two-step process, involves drying followed by burning. 

Decaborane is the most studied of all the polyhedral boranes and at one time (mid-1950s) was manufactured on a multitonne scale in the USA as a potential high-energy fuel. It is now obtainable in research quantities by the pyrolysis of B2H9 at 100-200°C in the presence of catalytic amounts of Lewis bases such as Me20. B10H14 is a colourless, volatile, crystalline solid (see Table 6.2, p. 163) which... 

C/o50-carboranes are the most numerous and the most stable of the carboranes. They are colourless volatile liquids or solids (depending on mol wt.) and can be prepared from an alkyne and a borane by pyrolysis, or by reaction in a silent electric discharge. This route, which generally gives mixtures, is particularly useful for small c/o50-carboranes (n = 5-7) and for some intermediate c/ow-carboranes (n = 8-11), e.g. 

In spray pyrolysis, very fine droplets are sprayed onto a heated substrate. The limitations of this process are the same as for spin-on coating. The same is often the case for preparing solid electrolytes by chemical vapor deposition (CVD) processes, which in addition are more expensive, and the precursors are often very toxic. 

D, W. Blair, CombustFlame 20 (1), 105—9 (1973) CA 78, 113515 (1973) A simple heat-transfer model is coupled with an Arrhenius-type pyrolysis law to study the effect of solid-state heat-transfer losses on burning rates of solid rocket-proplnt strands. Such heat-transfer losses materially affect the burning rates and also cause extinction phenomena similar to some that had been observed exptly. Strand diam and compn, adiabatic burning rate, and the heat-transfer film coeff at the strand surface are important variables. Results of theoretical analysis are applied to AP-based composite solid proplnts... 

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