Energy recovery by fast pyrolysis of pre-treated trommel fines derived from a UK-based MSW material recycling facility

In this experimental study, a physically pre-treated trommel fines feedstock, containing 44 wt% non-volatiles (ash and fixed carbon) and 56 wt% volatile matter (dry basis), was subjected to fast pyrolysis to recover energy from its organic load, using a 300 g h−1 bubbling fluidized bed (BFB) fast pyrolysis rig. A physical pre-treatment method (including crushing, grinding and sieving) was used to prepare a 0.5–2 mm sized trommel fines feedstock to make it suitable for fast pyrolysis in the BFB reactor. Experimental results from the fast pyrolysis process showed that the highest yield of organic liquid was obtained at around a temperature of 500 °C. However, both char and gas yields increased dramatically at temperatures above 500 °C, as a result of enhanced cracking of organic vapours, which reduced the yield of liquid products. Overall, energy recovery from the pyrolysis products (liquid and gas products as well as char pot residues) ranged from 63 to 70%, generally increasing with temperature. A large proportion of the high ash content (36 wt%) of the feedstock was found in the char pot (>62%), while smaller proportions were found in the reactor bed and some liquid products. The char pot ash residues composed mostly of non-hazardous earth materials and may be applied in bulk construction materials e.g. cement manufacture. Although, there was no problem with the pyrolysis rig during 1 h of operation, longer periods of operation would require periodic removal of accumulated solid residues and/or char pot modification to ensure continuous rig operation and process safety

Design and construction of an oven for drying palm bunch using glycerine as fuel together with using closed-loop oscillating heat-pipe with check valves (CLOHP/CV) heat exchanger for waste heat recovery

138-143This research addresses design and construction of an oven (2 m x 3 m x 2 m) for effectively drying palm bunch using glycerin as a fuel and a closed-loop oscillating heat-pipe with check valves (CLOHP/CV) as a heat exchanger for waste heat recovery. In each experiment, palm bunches (500 kg) were baked in oven with and without CLOHP/CV heat exchanger. CLOHP/CV (0.2 m x 0.8 m x 0.5 m) is made of copper tubes (inner diam, 2.03 mm). Working fluids were distilled water, ethanol and R134a. Waste heat from oven was recovered by heat exchanger and was beneficial for pre-heating the air in combustion process. Pre-heating was useful in burning glycerine, and distribution of heat inside oven with CLOHP/CV was better than without CLOHP/CV. Consequently, palm bunches received uniform heat that restrained enzyme thus slowing dissolution reactions that would otherwise produce free fatty acids and cause loss of palm oil. Use of a CLOHP/CV also reduced moisture content of palm bunches to 1.2 wt% on dry basis. When using oven with CLOHP/CV as a heat exchanger with R134a as working fluid, the highest thermal efficiency of drying palm bunch was 42.4%, highest effectiveness of CLOHP/CV was 43.0% and highest efficiency of glycerin stove was 45.0%

Catalytic fast pyrolysis of pine wood: Effect of successive catalyst regeneration

The main product of biomass fast pyrolysis is a liquid mixture of numerous organic molecules with water that is usually called pyrolysis oil or bio-oil. The research discussed in this paper was meant (1) to validate a new, semicontinuously operated pyrolysis setup and (2) to investigate the effect of a repeatedly regenerated ZSM-5-based catalyst (eight reaction/regeneration cycles in total) on the yields and compositions of the pyrolysis products in relation to the applied process conditions and on the catalyst itself. The reliability of the setup has been proven by multiple repetition of noncatalytic and catalytic (in situ) pyrolysis experiments for pine wood at 500 °C under identical conditions. As a result, the mass balance closures for all experiments varied from 92 to 99 wt %, while the scatter in measured data was always less than 5%. Changes in the performance of the repeatedly regenerated catalyst have been observed via detailed analysis of the bio-oil (GC × GC-FID and GC × GC-TOF-MS, Karl Fischer), the noncondensable gases (micro-GC), and the carbonaceous solids (elemental analyzer, BET surface area). Along the reaction/regeneration sequence, the yield of organics increased, while water, carbonaceous solids, and noncondensable gases decreased. Trends in pyrolysis product yields converging to that of noncatalytic levels were observed, which revealed that the influence of the catalyst slowly declined. The main observation was that the catalyst partially loses its activity in terms of the product distribution along the reaction/regeneration sequence, while retaining sufficient activity in producing the target chemical compounds