Kamil Kwiatkowski

From feathers to syngas - technologies and devices.

The poultry waste produced by industrial slaughterhouses typically contains not only feathers, but also a mixture of animal entrails, nails, blood, beaks and whole carcasses. Economical utilisation of this mixture, varying strongly in composition and moisture content, is, in general, difficult. We demonstrate that this awkward material can be successfully used for gasification in a simple, fixed-bed gasifier. The method of gasification, which we developed, enables control of the gasification process and ensures its stability in the operational regime of a working poultry processing plant. The installation, which has been working in Poland for 2 years, utilises 2 tons of feathers per hour and produces syngas of stable composition and fairly high quality. The syngas is burnt in the combustion chamber adjacent to the gasifier. Heat is recuperated in a boiler producing 3.5 tons per hour of technological steam continuously used for the operation of the slaughterhouse. The whole process complies with the stringent emission standards. In the paper we present the end-use device for feather utilisation and describe the underlying gasification and syngas combustion processes. Key elements of the whole installation are briefly discussed. The environmental impacts of the installation are summarized.

Numerical Modeling of Biomass Pyrolysis—Heat and Mass Transport Models

We consider the pyrolysis of robinia pseudoacacia, which is a common material for biomass gasifiers. We formulate three models of the process, with increasingly detailed physics, best suited for different spatial scales from large to small. For each model, we perform numerical simulations of adaptable complexity and compare the results with the thermogravimetric analysis (TGA) experiments.

Numerical simulations of industrial-scale combustion chamber - LES versus RANS

In this work we focus on the simulation of the process of biomass syngas combustion in the industrial combustion chamber directly linked with gasification chamber, where this gas is continuously producing from the biomass. Conflicting demands from the engineers to have rapid results and hints how to ensure the best conditions for combustion of this particular fuel and to lower the emission of pollutants, with simultaneously deep view inside the process and its stability motivates us to use both the RANS and LES techniques of turbulence modelling, compare it and take their advantages. We designed and performed series of 3D numerical simulations of both cold flow and combustion in complex geometry of industrial burner. It seems to us that the proper approach for modelling of biomass syngas combustion is steady flamelets model. Simulations performed with RANS closure are used as the initialisation of LES models, but their main goal is to predict the long-time oscillation of pressure and temperature observed in the working combustion chamber. On the other hand the main goal of the simulations with LES closure is to predict the proper level of short-time behaviour of the flame and local phenomena.

Pyrolysis and gasification of single biomass particle – new openFoam solver

We present a new solver biomassGasificationFoam that extended the functionalities of the well-supported open-source CFD code OpenFOAM. The main goal of this development is to provide a comprehensive computational environment for a wide range of applications involving reacting gases and solids. The biomassGasificationFoam is an integrated solver capable of modelling thermal conversion, including evaporation, pyrolysis, gasification, and combustion, of various solid materials. In the paper we show that the gas is hotter than the solid except at the centre of the sample, where the temperature of the solid is higher. This effect is expected because the thermal conductivity of the porous matrix of the solid phase is higher than the thermal conductivity of the gases. This effect, which cannot be considered if thermal equilibrium between the gas and solid is assumed, leads to precise description of heat transfer into wood particles.

Effect of mobility ratio on interaction between the fingers in unstable growth processes

We investigate interactions between thin fingers formed as a result of an instability of an advancing front in growth processes. We show that the fingers can both attract and repel each other, depending on their lengths and the mobility ratio between the invading and displaced phase. To understand the origin of these interactions we introduce a simple resistor model of the fingers. The predictions of the model are then compared to the numerical simulations of two unstable growth processes: dissolution of partially cemented rock fracture and viscous fingering in a regular network of channels.

Analysis and modelling of the effective reaction rate in a developing mixing layer

Simulations of the chemically reacting mixing layer were performed. Especially the early stage of the flow transition, when the coherent Kelvin-Helmholtz vortices can be recognized, was studied. This is a physical problem of great importance in many industrial and environmental systems. Simple passive reaction of the second order is considered. Its effective rate is analysed for different values of the Damkohler number. The results are compared to the case of the steady, laminar shear flow. It is found that slow and fast reactions respond in different ways to the fluctuations of the reactant concentration. Faster reactions appeared to be much more sensitive to the character of mixing. Moreover a buffer layer of product of fast reactions forms in the system and separates the substrates what influence the effective reaction rate.

Turbulence Behind 3D Multi-Scale Sparse Grids

A fundamentally new idea in grid generated turbulence is the 3D Sparse Grid (3DS) concept [N. A. Malik. Sparse 3D Multi-Scale Grid Turbulence Generator. US Patent No. US 9,599,269 B2 (2017)] which reduces the effective blockage ratio compared to the 2D flat fractal grids, s 3DS Lt s 2DF , and possess a much greater parameter space which could allow further optimization of the turbulence as compared to the 2D fractal (2DF) grids. Here, we report on some theoretical results regarding blockage ratio reduction in a 3-frame 3DS system, and some results from Direct Numerical Simulations comparing the turbulence characteristics generated by 3DS with Regular (RG) and 2DF grids cases.

Percolation thresholds for discrete-continuous models with nonuniform probabilities of bond formation.

We introduce a class of discrete-continuous percolation models and an efficient Monte Carlo algorithm for computing their properties. The class is general enough to include well-known discrete and continuous models as special cases. We focus on a particular example of such a model, a nanotube model of disintegration of activated carbon. We calculate its exact critical threshold in two dimensions and obtain a Monte Carlo estimate in three dimensions. Furthermore, we use this example to analyze and characterize the efficiency of our algorithm, by computing critical exponents and properties, finding that it compares favorably to well-known algorithms for simpler systems.