Martin Lisý

Energy Recovery from Contaminated Biomass

This study focuses on thermal gasification methods of contaminated biomass in an atmospheric fluidized bed, especially biomass contaminated by undesirable substances in its primary use. For the experiments, chipboard waste was chosen as a representative sample of contaminated biomass. In the experiments, samples of gas and tar were taken for a better description of the process of gasifying chipboard waste. Gas and tar samples also provide information about the properties of the gas that is produced.

Biomass Gasification — Primary Methods for Eliminating Tar

This present paper deals with primary methods for reducing tar in biomass gasification, namely by feeding a natural catalyst into a fluidized bed. This method is verified using an experimental pilot plant.

TECHNICAL AND ECONOMIC OPTIMIZATION OF COGENERATION TECHNOLOGY USING COMBUSTION AND GASIFICATION

This paper presents the technical and economic optimization of new microcogeneration technology with biomass combustion or biomass gasification used for cogeneration of electrical energy and heat for a 200 kW unit. During the development phase, six possible connection solutions were investigated, elaborated and optimized. This paper presents a basic description of the technology, a description of the technological solutions, and especially the results of balance and financial calculations, ending with a comparison and evaluation of the results.

The Effect of Temperature on the Gasification Process

Gasification is a technology that uses fuel to produce power and heat. This technology is also suitable for biomass conversion. Biomass is a renewable energy source that is being developed to diversify the energy mix, so that the Czech Republic can reduce its dependence on fossil fuels and on raw materials for energy imported from abroad. During gasification, biomass is converted into a gas that can then be burned in a gas burner, with all the advantages of gas combustion. Alternatively, it can be used in internal combustion engines. The main task during gasification is to achieve maximum purity and maximum calorific value of the gas. The main factors are the type of gasifier, the gasification medium, biomass quality and, last but not least, the gasification mode itself. This paper describes experiments that investigate the effect of temperature and pressure on gas composition and low calorific value. The experiments were performed in an atmospheric gasifier in the laboratories of the Energy Institute atthe Faculty of Mechanical Engineering, Brno University of Technology.

Optimization of Secondary Air Distribution in Biomass Boiler by CFD Analysis

This paper deals with a use of CFD modelling for optimization of supply of secondary combustion air in the two-chamber biomass boiler combusting very wet biomass (capacity ca. 200 kW). Objective of the analyse is to observe the impact of diameter of a secondary air supply pipe and air flow velocity on mixing of the secondary air with flue gas in the combustion chamber. The numerical model of the experimental boiler was build up for subsequent utilizing of CFD computation based on finite element method. The commercial code STAR-CD was used for carried out parametrical studies. Series of calculations were carried out for four different diameters of air distribution pipes and for 3 different air velocities in distribution orifice. Quality of air dispersion in flue gas flow was assessed in the vertical cross section lead in the end of the combustion chamber. The results of calculation were verified on the experimental installation of the boiler. Influence of secondary air mixing on emission production was measured and analysed. Emissions of pollutants for recommended air distribution comply with emission limits stipulated in the most stringent class 5 according to ČSN-EN 303-5 as well as with emission limits under Regulation No. 405/2012 Sb.

Numerical Study of Air Distribution in Combustion Chamber

The main goal of this article is to analyze the distribution of primary and secondary combustion air in a combustion chamber. The fuel for the combustion chamber is biomass and the main characteristics the combustion chamber must meet is to be simple, reliable, cheap and ecological. A brief summary of the importance of primary and secondary air is made and then it is compared with the results from the numerical model. The numerical model is based upon a simplified chamber geometry and the results are computed for laminar and turbulent flow. From the comparison are determined flaws of the design of the combustion chamber and outlined possible solutions for their removal and further direction of the study.

Steam Biomass Gasification - Effect of Temperature

Gasification is one of the technologies for utilization of biomass. Gasification is a transformation process that converts solid fuels into gaseous fuels. The gaseous fuel may be subsequently applied in other technologies with all the benefits that gaseous fuels provide. The principle of biomass gasification is a common knowledge. It is thermochemical decomposition oof the fuel in presence of gasification agent. Heat from the endothermic reaction is obtained by a partial combustion of the fuel (autothermal gasification) or the heat is supplied into a gasifier from the outside (allothermal gasification). Oxygen for the partial combustion is supplied in the gasification medium. Quality, composition and amount of the producer gas depend on many factors which include type of the gasifier, operating temperature and pressure, fuel properties (moisture content) and type and amount of gasification medium. Commonly, air, steam and oxygen and their combinations are used as a gasification medium. Every kind of gasification agents has its significant advantages and disadvantages.Research and analysis of the gasification process must pay special attention to all operating parameters which affect quality and amount of the producer gas that is the efficiency of the conversion itself. Composition of the producer gas, calorific value, and content and composition of impurities are especially observed as these are the basic characteristics directly affecting subsequent application of the gas. Steam addition has a significant impact on gas composition. Steam decomposition into hydrogen and oxygen, and their subsequent reactions increases amount of combustibles, hydrogen, methane and other hydrocarbons. Steam addition in the gasification also affects amount and composition of tar and has a negative impact on heat balance.Energy Institute at the Brno University of Technology has a long tradition in research of biomass gasification in atmospheric fluidized bed reactors. Air was used as a gasification medium. This paper describes our experience with gasification using a mixture of air and steam. We analysed the whole process and in this paper we wish to describe the impact of temperature on outputs of the process, especially temperature of leaving steam and temperature of gasification reactions.

Effect of size sprinkled heat exchange surface on developing boiling

This article presents research of sprinkled heat exchangers. This type of research has become rather topical in relation to sea water desalination. This process uses sprinkling of exchangers which rapidly separates vapour phase from a liquid phase. Applications help better utilize low-potential heat which is commonly wasted in utility systems. Low-potential heat may increase utilization of primary materials. Our ambition is to analyse and describe the whole sprinkled exchanger. Two heat exchangers were tested with a similar tube pitch: heat exchanger no. 1 had a four-tube bundle and heat exchanger no. 2 had eight-tube bundle. Efforts were made to maintain similar physical characteristics. They were tested at two flow rates (ca 0.07 and 0.11 kg s−1 m−1) and progress of boiling on the bundle was observed. Initial pressure was ca 10 kPa (abs) at which no liquid was boiling at any part of the exchanger; the pressure was then lowered. Other input parameters were roughly similar for both flow rates. Temperature of heating water was ca 50°C at a constant flow rate of ca 7.2 L min−1. Results of our experiments provide optimum parameters for the given conditions for both tube bundles.

OPTIMALIZATION OF AFTERBURNER CHANNEL IN BIOMASS BOILER USING CFD ANALYSIS

This contribution presents the results of parametrical studies focused on the mixing process in a small rectangular duct within a biomass boiler. The first study investigates the influence of a local narrowing located in the central part of the duct. This narrowing works as an orifice with very simple rectangular geometry. Four different free cross sections of the orifice were considered in the center of the duct, namely 100%, 70%, 50%, 30% of free cross section area in the duct. The second study is focused on the investigation of the influence of secondary air distribution pipe diameter on the mixing process in a flue gas duct without a narrowing.

OPERATING SPECIFICATIONS OF CATALYTIC CLEANING OF GAS FROM BIOMASS GASIFICATION

The paper focuses on the theoretical description of the cleaning of syngas from biomass and waste gasification using catalytic methods, and on the verification of the theory through experiments. The main obstruction to using syngas from fluid gasification of organic matter is the presence of various high-boiling point hydrocarbons (i.e., tar) in the gas. The elimination of tar from the gas is a key factor in subsequent use of the gas in other technologies for cogeneration of electrical energy and heat. The application of a natural or artificial catalyst for catalytic destruction of tar is one of the methods of secondary elimination of tar from syngas. In our experiments, we used a natural catalyst (dolomite or calcium magnesium carbonate) from Horni Lanov with great mechanical and catalytic properties, suitable for our purposes. The advantages of natural catalysts in contrast to artificial catalysts include their availability, low purchase prices and higher resilience to the so-called catalyst poison. Natural calcium catalysts may also capture undesired compounds of sulphure and chlorine. Our paper presents a theoretical description and analysis of catalytic destruction of tar into combustible gas components, and of the impact of dolomite calcination on its efficiency. The efficiency of the technology is verified in laboratories. The facility used for verification was a 150 kW pilot gasification unit with a laboratory catalytic filter. The efficiency of tar elimination reached 99.5%, the tar concentration complied with limits for use of the gas in combustion engines, and the tar content reached approximately 35 mg/m n 3 . The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.