High-temperature short-time fluidized

These principles formed the basis for producing high quality carrots and potatoes by a process of biopolymer infusion followed by high temperature short time fluidized bed dehydration. Infused biopolymers was shown to penetrate intracellular spaces and cell walls and may contribute to reduced cell collapse in the dehydration process. Deposition of infused biopolymer within the cells was elucidated using a convalently bound complex of biopolymer and colored dye which was visible upon histochemical examinations under a microscope. The dehydration process was optimized with response surface methodology. The resulting products have excellent quality, high rehydration ratio and a puffed structure. 

Recycling to monomers, fuel oils or other valuable chemicals from the waste polymers has been attractive and sometimes the system has been commercially operated [1-4]. It has been understood that, in the thermal decomposition of polymers, the residence time distribution (RTD) of the vapor phase in the reactor has been one of the major factors in determining the products distribution and yield, since the products are usually generated as a vapor phase at a high temperature. The RTD of the vapor phase becomes more important in fluidized bed reactors where the residence time of the vapor phase is usually very short. The residence time of the vapor or gas phase has been controlled by generating a swirling flow motion in the reactor [5-8]. 

The high selectivity to styrene during PS pyrolysis does not appear to depend on the type of reactor used. Thus, Sinn et a/.33 reported styrene yields of 79.8 and 71.6% when the pyrolysis was carried out in a sand fluidized bed reactor at 640 and 740 °C, respectively. Styrene yields of up to 92% have recently been reported by Lovett et al.30 during PS pyrolysis in a microreactor at high temperature (965 °C) and very short residence times (500 ms). 

Methods for the conversion of biomass into a slate of product, also comprising chemicals like p-xylene, are those promoted by US-based companies Anellotech and Virent. In Anellotech s Biomass to Aromatics process, biomass such as corn, sugar beet and so on is dried and milled, and then injected into a fluidized bed in the presence of a cheap zeolite, based on ZSM-5. The process takes place at high temperatures (600 °C) at a short period of time. Coking initially was considered as a drawback in this process. Annellotech claims to be able to produce 190 L product out of 1 ton biomass (www.anellotech.com, accessed 22 June 2013). So far the process has been performed on a small scale only and scale-up needs to be realized. 

This makes the residence time at reaction temperature uncertain. A continuous operation avoids this problem, but the backmixing in a fluidized bed leads to short-circuiting of some untreated coal. For this program, a continuous unit capable of fairly high throughput was designed and built. 

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