Reactor design, pyrolysis

Heterogeneous kinetics of straw pyrolysis and straw gasification are essentia data for reactor design. Pyrolysis is a relatively fast process. In view of the poor heat conduction of straw and straw char, the pyrolysis time is the time which is required to heat the center of the particle to the decomposition temperature. This is a rather simplified model, but allows a reasonable time estimate in view of the order of magnitude. 

In this pyrolysis, sub atmospheric partial pressures are achieved by employing a diluent such as steam. Because of the corrosive nature of the acids (HE and HCl) formed, the reactor design should include a platinum-lined tubular reactor made of nickel to allow atmospheric pressure reactions to be mn in the presence of a diluent. Because the pyrolysate contains numerous by-products that adversely affect polymerization, the TFE must be purified. Refinement of TFE is an extremely complex process, which contributes to the high cost of the monomer. Inhibitors are added to the purified monomer to avoid polymerization during storage terpenes such as t7-limonene and terpene B are effective (10). 

Nearly all of the processes used for tire pyrolysis have the same basic unit operation, with variations in the reactor design. First, this chapter describes the basic process... 

As mentioned earlier, a number of different types of reactors have been tried in tire pyrolysis. Almost any vessel that can be sealed can be used as a pyrolysis reactor. Reactor design has a significant effect on the quality of char produced, due to a uniform temperature gradient, and the abrasion of the particles with one another. Some of the reactor types that have been used are ... 

A Systems Approach to Optimum Pyrolysis Reactor Design... 

Figure 1 shows a computational framework, representing many years of Braun s research and development efforts in pyrolysis technology. Input to the system is a data base including pilot, commercial and literature sources. The data form the basis of a pyrolysis reactor model consistent with both theoretical and practical considerations. Modern computational techniques are used in the identification of model parameters. The model is then incorporated into a computer system capable of handling a wide range of industrial problems. Some of the applications are reactor design, economic and flexibility studies and process optimization and control. 

Design of Pyrolysis Reactors. A pyrolysis reactor is to be designed for a fixed feed rate and composition such that the outlet conditions must meet the specifications,... 

The considerations and the experimental evidence just described suggest that the reactor design as well as the definition of process conditions need a tool, able to provide reliable predictions for the on-set of fluidization worsening and bed defluidization. Mastellone and Arena [37] proposed a predictive defluidization model valid for low-temperature pyrolysis... 

Figure 19.5 Reactor design of Conrad pyrolysis plant [10]. (Reproduced by permission of the US Copyright Office)...

The pyrolysis experiments were conducted in an electrically heated, once-through tubular flow reactor, designed to simulate the time-temperature history experienced in commercial steam-cracking operations. Reactor effluent compositions were ascertained by gas chromatograph and mass spectrometer analyses. Material and hydrogen balances could always be effected, with typical closures of 98 2 wt %. 

A laboratory reactor system was constructed for the investigation of tar conversion under real fixed-bed conditions. The basic idea behind the reactor design was the spatial separation of primary pyrolysis and secondary tar reactions. A scheme of the system is shown in fig, 2. After the primary pyrolysis stage, the tar containing pyrolysis gas is swept to the conversion reactors where homogeneous and/or heterogeneous tar reactions can be investigated. 

Pyrolysis oil yield and composition are functions of reactor design and operating conditions, especially temperature, and the raw pyrolysis oil composition can be modified to improve yield and selectivity for higher value chemical products in order to produce a better return than from fuel use alone. 

This paper uses pyrolysis products from an air-blown, fluidized-bed reactor designed to produce liquids for use in adhesives as an illustration of what might be produced, separated and sold commercially for higher value. Guidelines for chemicals production and product recovery are suggested for pyrolysis processes in general. Recommended research and development topics to aid commercialization and increase chemical product recovery and project cash flow are presented. 

Figure 2 Chemical and Transport Phenomena Occurring in a Vacuum Pyrolysis Reactor and Their Role in Reactor Design.

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