Design Of Pyrolysis Reactors Research Articles

Cattle manure pyrolysis process: Kinetic and thermodynamic analysis with isoconversional methods

The kinetic and thermodynamic behaviors of the pyrolysis process of cattle manure are greatly important for the understanding of its prolysis mechanism and the design of pyrolysis reactors. In this research, the thermogravimetric analysis (TGA) experiments of cattle manure were firstly implemented with six different heating rates, e.g. 10, 20, 30, 40, 60 and 80 °C min−1. And then, the activation energies (E) during the pyrolysis process were calculated with four isoconversional methods (e.g., Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink methods); the thermodynamic behavior was addressed by considering the thermodynamic parameters including pre-exponential factor (A), as well as the changes of enthalpy (ΔH), free Gibbs energy (ΔG), and entropy (ΔS). Results demonstrates that the pyrolysis process is constituted by a multi-stage reaction and can be roughly divided into three stages with the increase of conversion degrees (α): Stage I (α = 0.05–0.35) represents the dominating reaction zone of the extractives and hemicellulose component, stage II (α = 0.35–0.55) cellulose and lignin components, and stage III (α = 0.55–0.85) lignin and mineral components. The decomposition processes of each component have no clear boundaries and interact with each other. The complex mechanism of cattle manure pyrolysis is also revealed with the thermodynamic analysis.

Pyrolysis characteristics and kinetics of acid tar waste from crude benzol refining: A thermogravimetry-mass spectrometry analysis.

Pyrolysis is an attractive thermochemical conversion technology that may be utilised as a safe disposal option for acid tar waste. The kinetics of acid tar pyrolysis were investigated using thermogravimetry coupled with mass spectrometry under a nitrogen atmosphere at different heating rates of 10, 15 and 20 K min-1 The thermogravimetric analysis shows three major reaction peaks centred around 178 °C, 258 °C, and 336 °C corresponding to the successive degradation of water soluble lower molecular mass sulphonic acids, sulphonated high molecular mass hydrocarbons, and high molecular mass hydrocarbons. The kinetic parameters were evaluated using the iso-conversional Kissinger-Akahira-Sunose method. A variation in the activation energy with conversion revealed that the pyrolysis of the acid tar waste progresses through complex multi-step kinetics. Mass spectrometry results revealed a predominance of gases such as hydrogen, methane and carbon monoxide, implying that the pyrolysis of acid tar waste is potentially an energy source. Thus the pyrolysis of acid tar waste may present a viable option for its environmental treatment. There are however, some limitations imposed by the co-evolution of corrosive gaseous components for which appropriate considerations must be provided in both pyrolysis reactor design and selection of construction materials.

Kinetic Modeling and Simulation of Pyrolysis of Shrinking BiomassParticle in Fixed Bed Gasifier

A B S T R A C T Pyrolysis plays an integrated role in the biomass conversion processes. The development of good mathematical models which in consequent leads to the design of pyrolysis reactors. The biomass gasifier is paramount in the scientific studies and understanding of the very important process in the thermochemical conversion of the solid fuels. However, due to the complexities of the biomass reaction scheme, the pyrolysis of biomass is generally modeled on the basis of apparent kinetics. Moreover, it is generally accepted that most important parameters affecting the process are temperature, concentration, residence time and heating conditions. This work presents the simulations of the pyrolysis kinetics of shrinking biomass particle under non-isothermal and isothermal heating conditions. The developed models were used to investigate the effects of shrinkage, heating conditions and heating rates on the pyrolysis of wood. There is a good agreement when the results of the developed models were compared to the experimental results. Theresults of this work could be used in estimating the optimum parameters in the pyrolysis of biomass and in the design of some pyrolysis reactors.

Theoretical Investigations of the Effects of Isothermal and Non-isothermal Heating Conditions on the Pyrolysis Kinetics of Biomass Particle

There has been a growing interest in renewable energy sources from various part of the world over the past decades. One of the promising alternatives to fossil fuels is biomass and in all the common technologies of its conversion, pyrolysis is present atleast as a first stage of the conversion process. As part of the scientific studies and understanding of this very important process in the thermochemical conversion of the solid fuel, the development of good mathematical models which in consequent leads to the design of pyrolysis reactors and biomass gasifiers is paramount. However, due to the complexities of the biomass reaction scheme, the pyrolysis of biomass is generally modeled on the basis of apparent kinetics. Moreover, most of the past works were based on the overall pyrolysis kinetics, and studies concerning pyrolysis products are much less common. Therefore, this work presents the analytical solutions of the kinetics of pyrolysis of biomass particle under non-isothermal and isothermal heating conditions. The developed models were used to investigate the effects of heating conditions and heating rates on the pyrolysis of wood products. The comparison of the simulated results with the available results reported in literatures show good agreements were found. This work could be used in predetermining the biomass products concentrations under different heating conditions and the estimating the optimum parameters in the pyrolysis of biomass and in the design of some pyrolysis reactors/units.

CFD Modeling of Algae Flash Pyrolysis in the Batch Fluidized Bed Reactor Including Heat Carrier Particles

Abstract The algae biomass is one of the potential biomass resources for extracting lipid to produce fuel. The off grade or residuals of dehydrated algae particles can be used in pyrolysis reactions to produce fuel or useful chemicals. Due to higher ash contents of algae biomass, pyrolysis process needs an appropriate design of pyrolysis reactor. The heating rate of algae biomass is a key factor for increasing of bio-oil production rate. Instead of heat transfer from reactor walls to the biomass, heated inert particles are added to the conventional fluidized bed reactor to increase heat transfer rate and yield of the bio-oil as called flash pyrolysis. The introduced pyrolysis reaction in the novel heating method of fluidized bed reactor studied numerically. For this purpose, an Eulerian-Eulerian CFD model utilized for modeling of the dehydrated algae pyrolysis in the fluidized bed reactor. The appropriate reaction rate of the algae pyrolysis is based on the heating rate, temperature sensitive activation energy and the reaction selectivity utilized to the algae pyrolysis. In addition, the segregation and density change of the biomass particles investigated in the CFD modeling to analysis mixing of the particles and corresponding heat transfer between the mixed particles. The validation of the CFD model investigated using results of prepared experimental setup.

An overview of distributed activation energy model and its application in the pyrolysis of lignocellulosic biomass

Research interest in the conversion of lignocellulosic biomass into energy and fuels through the pyrolysis process has increased significantly in the last decade as the necessity for a renewable source of carbon has become more evident. For optimal design of pyrolysis reactors, an understanding of the pyrolysis kinetics of lignocellulosic biomass is of fundamental importance. The distributed activation energy model (DAEM) has been usually used to describe the pyrolysis kinetics of lignocellulosic biomass. In this review, we start with the derivation of the DAEM. After an overview of the activation energy distribution and frequency factor in the DAEM, we focus on the numerical calculation and parameter estimation methods of the DAEM. Finally, this review summarizes recent results published in the literature for the application of the DAEM to the pyrolysis kinetics of lignocellulosic biomass.

Analytical Investigations of Kinetic and Heat Transfer in Slow Pyrolysis of a Biomass Particle

The utilization of biomass for heat and power generation has aroused the interest of most researchers especially those of energy .In converting solid fuel to a usable form of energy, pyrolysis plays an integral role. Understanding this very important phenomenon in the thermochemical conversion processes and representing it with appropriate mathematical models is vital in the design of pyrolysis reactors and biomass gasifiers. Therefore, this study presents analytical solutions to the kinetic and the heat transfer equations that describe the slow pyrolysis of a biomass particle. The effects of Biot number, temperature and residence time on biomass particle decomposition were studied. The results from the proposed analytical models are in good agreement with the reported experimental results. The developed analytical solutions to the heat transfer equations which have been stated to be “analytically involved” showed average percentage error and standard deviations 0.439 and 0.103 from the experimental results respectively as compared with previous model in literature which gives average percentage error and standard deviations 0.75 and 0.106 from the experimental results respectively. This work is of great importance in the design of some pyrolysis reactors/units and in the optimal design of the biomass gasifiers.

Biofuels Production through Biomass Pyrolysis —A Technological Review

There has been an enormous amount of research in recent years in the area of thermo-chemical conversion of biomass into bio-fuels (bio-oil, bio-char and bio-gas) through pyrolysis technology due to its several socio-economic advantages as well as the fact it is an efficient conversion method compared to other thermo-chemical conversion technologies. However, this technology is not yet fully developed with respect to its commercial applications. In this study, more than two hundred publications are reviewed, discussed and summarized, with the emphasis being placed on the current status of pyrolysis technology and its potential for commercial applications for bio-fuel production. Aspects of pyrolysis technology such as pyrolysis principles, biomass sources and characteristics, types of pyrolysis, pyrolysis reactor design, pyrolysis products and their characteristics and economics of bio-fuel production are presented. It is found from this study that conversion of biomass to bio-fuel has to overcome challenges such as understanding the trade-off between the size of the pyrolysis plant and feedstock, improvement of the reliability of pyrolysis reactors and processes to become viable for commercial applications. Further study is required to achieve a better understanding of the economics of biomass pyrolysis for bio-fuel production, as well as resolving issues related to the capabilities of this technology in practical application.

Vacuum Paddle Fast Pyrolysis Reactor Design and Internal Heat Transfer Investigation

Fast pyrolysis is cracking process in which macromolecule of biomass is broken into small molecular under moderate temperature and at high heating speed. Bio-oil produced by the process can be used as potential alternatives of diesel oil and other chemicals. By investigate different kinds of reactor, a new type reactor called vacuum paddle fast pryoysis reactor is developed with low manufacture cost and operating fee and more stable performance. Two stage condensing system composed of 1st quench stage and 2nd cooling heat exchanger is designed, which is proven effective in avoiding secondary cracking of biomass oil and eliminating block of equipment by tar. At same time, a model describing heat transfer in new reactor is established and solved by unsteady heat conduction equation, which give conclusion on minimum agitating speed and therefore, provide basic theoretical foundation. Keywords: fast pyrolysis, vacuum paddle reactor, condenser, heat transfer

Production of Energy and Activated Carbon from Agri-Residue: Sunflower Seed Example

In this work, a biomass processing facility is designed and simulated for the annual conversion of 77 ktons of sunflower residue into electricity and activated carbon. The residue is initially pyrolized to produce low hydrocarbon gases (35 wt%), bio-oils (30 wt%), and char (35 wt%). The gases and bio-oils are separated and combusted to generate high pressure steam, electricity, and steam for conversion of char into activated carbon. Assuming 35% of the char's mass is lost during activation, the proposed process produces 15.6 ktons activated carbon and 5.5 ktons ash annually, while generating 10.2 MW of electricity. Economic analysis of the proposed facility yielded capital costs of $31.64 million, annual operating costs of $31.58 million, and a yearly gross revenue of $38.9 million. A discounted payback period of 6.1 years was determined for the current design, extending to 10 years if the facility were operated at 75% capacity. While the proposed process appears to be economically viable, profitability is highly sensitive to the selling price of electricity and activated carbon, highlighting the need for additional research into the pyrolysis reactor design, char/ash separation techniques, and the quality of activated carbon obtained using char from sunflower residue pyrolysis.

Differential Evolution Approach for Obtaining Kinetic Parameters in Nonisothermal Pyrolysis of Biomass

Pyrolysis, a first step in the biomass gasification, is the thermal decomposition of organic matter under inert atmospheric conditions, leading to the release of volatiles and formation of char. As pyrolysis is a kinetically controlled reaction, kinetic parameter estimation is very important in the design of pyrolysis reactors. In the proposed kinetic model of this study, the kinetic scheme of biomass decomposition by two competing reactions giving gaseous volatiles and solid charcoal is used. Four different models are proposed based on different possible relation of activity of biomass with normalized conversion. The corresponding kinetic parameters of the above models are estimated by minimizing the square of the error between the reported nonisothermal experimental data of thermogravimetry of hazelnut shell and simulated model predicted values of residual weight fraction using differential evolution (DE), a population-based search algorithm. Among the four different models proposed in this study, the model in which rate of change of activity of biomass with normalized conversion proposed as a function of activity itself gave the best agreement with the experimental data.

Pyrolysis of biomass: improved models for simultaneous kinetics and transport of heat, mass and momentum

Understanding the physical phenomena of pyrolysis and representing them with an appropriate mathematical model is essential in the design of pyrolysis reactors and biomass gasifiers. Description of the chemical processes of pyrolysis is coupled to an unsteady state, one dimensional, variable property model of transport phenomena, including heat convection, conduction and radiation, volatiles and gas transport by diffusion and convection and momentum transfer. In this study, a generalized reference model (Model I) incorporating all the above effects is proposed. This is further improved by proposing two simplified models (Models II and III) incorporating additional assumptions. A finite difference pure implicit scheme utilizing a Tri-Diagonal Matrix Algorithm (TDMA) is employed for solving the heat transfer and mass transfer model equations. A Runge–Kutta fourth order method is used for the chemical kinetics model equations. Simulations are performed considering different geometries of equivalent radius ranging from 0.0001 to 0.017 m and temperatures ranging from 303 to 2800 K. The results obtained using these improved models are in excellent agreement with the experimental data, much better than the agreement with earlier models reported in the literature. The improved validated model, which is best suited for wide ranges of operating conditions, is utilized to investigate the influence of particle size, particle shape, product distribution, conversion time and heat of reaction.

Cracking severity index in pyrolysis of petroleum fractions

The central problem in developing a sound pyrolysis model for petroleum fractions such as naphthas and gas oils is that of characterizing feed conversion, or cracking severity. Direct measurements of feed conversion are precluded by the large number of feed components and the difficulty of quantitatively analyzing them in reactor effluents. In this work a cracking severity model is presented wherein feed conversion is expressed in terms of readily accessible parameters, the C/sub 3/ and lighter yield and the hydrogen content of the C/sub 5/+ product. Theoretical development of the model is followed by the validation against both in-house pilot and literature data. The severity parameter is seen to provide a more realistic interpretation of yield structure, and by introduction of suitable feed characterization parameters can be applied as a general pyrolysis reactor design tool. This work is of interest in the design of a pyrolysis reactor. 37 refs.