No abstract

Biomass is one of the most promising renewable energy sources because it enables energy accumulation and controlled production. With this, however, the demand for biofuels grows and thus there is an effort to expand their portfolio. Nevertheless, to use a broader range of biofuels, it is necessary to know their fuel properties, such as coarse and elemental analysis, or lower heating value. This paper presents the results of testing the fuel properties of several new, potentially usable biofuels, such as quinoa, camelina, crambe, and safflower, which are compared with some traditional biofuels (wood, straw, sorrel, hay). Moreover, the results of the determination of water content, ash, and volatile combustible content of these fuels are included, along with the results of the elemental analysis and the determination of higher and lower heating values. Based on these properties, it is possible to implement designs of combustion plants of different outputs for these fuels.

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 Horní Lánov 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_n³. The results of the measurements conducted in laboratories helped us design a pilot technology for catalytic gas cleaning.

emphasis is given to accurate prediction of their properties, especially strength. There are several options for predicting pin connections, such as analytical calculations, Special-Purpose Programs (SPPs), or Finite Element Analysis (FEA). Nowadays companies do not usually have all these prediction methods available. The main reason is price and the maintenance of the software. In particular, smaller companies are usually equipped with SPPs [

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.

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.

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.

A sprinkled tube bundle is frequently used in technology processes where an increase or decrease of a liquid temperature in a very low-pressure environment is required. Phase transitions of the liquid very often occur at low temperatures at pressures ranging in the thousands of pascals, which enhances the heat transfer. This paper focuses on the issue of a heat-transfer coefficient that is experimentally examined at the surface of a tube bundle. The tube is located in a low-pressure chamber where the vacuum is generated using an exhauster via an ejector. The tube consists of smooth copper tubes of 12 mm diameter placed horizontally one above another. Heating water flows in the bundle from the bottom towards the top at an average input temperature of approximately 40°C and an average flow rate of approximately 7.2 L min -1 . A falling film liquid at an initial temperature of approximately 15°C at an initial tested pressure of approximately 97 kPa (atmospheric pressure) is sprinkled onto the tubes' surface. Afterwards, the pressure in the chamber is gradually decreased. When reaching the minimum pressure of approximately 3 kPa (abs) the water partially evaporates at the lower part of the bundle. Consequently, the influence of the falling film liquid temperature increase is tested. This gradually leads to the boiling of water in a significant part of the bundle and the residual cooling liquid that drops back to the bottom of the vessel is almost not heated anymore. In this paper we present the influences of the size of the heat-transfer surfaces. Keywords: sprinkled tube bundle, water, under pressure, heat transfer Pr{enje po snopu cevi se pogosto uporablja v tehnolo{kih procesih, kjer se zahteva povi{anje ali zmanj{anje temperature teko~ine v okolju z nizkim tlakom. Fazni prehod teko~ine se pogosto pojavi pri nizkih temperaturah in tlakih v obmo~ju nekaj tiso~paskalov, kar vpliva na prenos toplote.^lanek se nana{a na koeficient prenosa toplote, ki je eksperimentalno dolo~en na povr{ini snopa cevi. Cev je name{~ena v nizkotla~ni komori, kjer se vakuum ustvarja s pomo~jo aspiratorja preko ejektorja. Snop cevi sestavljajo gladke bakrene cevi, premera 12 mm, ki so name{~ene horizontalno ena nad drugo. Voda za ogrevanje te~e v snop od spodaj proti vrhu s povpre~no temperaturo okrog 40°C in povpre~no hitrostjo pretoka okrog 7,2 L min -1 . Padajoṽ odni film z za~etno temperaturo okrog 15°C in z za~etnim tlakom okrog 97 kPa (atmosferski tlak) pr{i po povr{ini cevi. Tlak se v komori postopno zni`uje. Ko dose`e minimalni tlak okrog 3 kPa (absolutni tlak) voda delno izhlapi na spodnjem delu snopa. Posledi~no je preizku{en vpliv nara{~anja temperature padajo~e vode. To postopno privede do vrenja vode na ve~jem delu povr{ine snopa in preostala hladilna teko~ina, ki kaplja na dno posode, se skoraj ne segreje ve~.^lanek predstavlja vpliv velikosti povr{ine kjer se prena{a toplota. Klju~ne besede: pr{enje po snopu cevi, podtlak, prenos toplote