ASH MELTING TEMPERATURE PREDICTION FROM CHEMICAL COMPOSITION OF BIOMASS ASH

Solid fuels, including biomass, consist of combustible, ash and water. Ash in fuel is result of reaction of minerals presented in the biomass. Minerals and other different substances which form ash got into biomass during growth. Ash is solid residue resulted from the perfect laboratory combustion of fuel. It is composed of minerals that are present in the fuel. Some species of biomass ash have low ash melting temperature and can cause various problems in combustion boilers. Ash slags and sinters can avoid heat transfer in heat exchangers, which can cause corrosion of heat transfer surfaces.Ash melting temperature can be determined on the basis of standard STN ISO 540 in some laboratory. Meltability of ash is characterized by the physical state of the ash, which occurs during the heating process under well-defined conditions in furnace. There exist 4 types of ash melting temperature - Shrinkage temperature (ST), Deformation temperature (DT), Hemisphere temperature (HT) and Flow temperature (FT). Experimental determination of ash melting temperature is quite expensive. In paper is described method of prediction ash melting temperature from known chemical composition of biomass ash. There is proposed mathematic model for determination of all ash melting temperatures. There is need to know the proportion of SiO2, CaO, K2O, MgO and Al2O3 in biomass ash. The mathematical model is relatively accurate with real ash melting temperatures and reaches accuracy about 90 % compared with ash melting temperatures obtained by STN ISO 540 method

Mathematical Model for Prediction of Biomass Ash Melting Temperature using Additives

Some types of biomass ash have low ash melting temperature which can result in various problems in combustion processes. Ash slags and sinters can avoid heat transfer in heat exchangers, which can also cause corrosion of heat transfer surfaces. One of the ways of burning fuels with low ash melting temperature is to use additives. Ash melting temperature can be determined in a laboratory on the basis of standard STN ISO 540. Meltability of ash is characterized by the physical state of ash occurring during the heating process under well-defined conditions in the furnace. Experimental determination of ash melting temperature is quite expensive. In this work a prediction method of ash melting temperature is described. The mathematical model uses multiple linear regression where input parameters are the known chemical composition of fuel ash and used additive converted to an amount of SiO2, CaO, K2O, MgO and Al2O3. The mathematical model is relatively accurate with real ash melting temperatures and reaches accuracy about of 90 % compared with ash melting temperatures obtained by STN ISO 540 method in a laboratory

Numerical Modelling of Emission Formation in Domestic Boiler for Coal

The aim of the work is to develop a method of simple haracterization of solid fuels combustion in fixed bed, which would be useful for CFD modelling. In this work, the measurements were performed in a test rig, where a combustion front propagates against the airflow. Concentrations of flue gas species were registered at the exit of a fixed bed reactor and the temperature of burning coal was measured in selected points of the reactor as functions of time

Simple Model of Pellet Combustion in Retort Burner

Combustion of the solid fuel in the burner is an important issue when discussing the CFD simulation of combustion in automatic boiler. In the present work is employed a simplified method for modeling the fuel bed, which is based on mass and heat balances in order to simplify the simulation of combustion in pellet boiler. The model for solid fuel combustion in a burner is created for the purpose of automatic boiler simulations. Such approach does not require a detailed bed model of fired solid fuel. A simple model of the bed can be very useful for designers and engineers of automatic boilers. The described approach to modeling the combustion process in a burner helps to shorten the calculation time and simplify the model of pellet combustion in various types of automatic boilers for households

Option of Solid Pollutants Abatement in Flue Gas Path

Biomass combustion produces gaseous and solid pollution. Solid pollutants are small particles which are getting into the air with smoke and may be harmful to the environment, the human and animal health. Therefore, it is important to decrease their amount in the ambient atmosphere. Particulate matter sources are not only big combustion devices but also small combustion devices which are quite common and widely used. It is necessary to mention that the small boilers are not as monitored as bigger ones. Therefore, they are potentially a large source of pollution. The main objective of this work is to reduce particulate matter concentration produced by small residential combustion appliances by making a change of the geometric parameters in a flue gas path

Use of Stirling Engine for Waste Heat Recovery

Even though this discovery dates back to 1816, the greatest advancement in technology and understanding of Stirling-cycle devices has occurred in the last 50 years. Although their mass production is currently limited to special-purpose machines, its prospective use is in combination with renewable sources and indicates a potential for commercial purposes. The lack of commercial success, despite obvious advantages, is probably due to a lack of appropriate modeling techniques and theoretical predictions of what these devices can achieve. Nowadays the Stirling engine has found its use mainly in solar power plants, where it represents the only piston engine converting solar energy into mechanical and then electricity with relatively high efficiency. The Stirling engine also appears to be suitable for recovering waste heat, especially in heavy industry. The numerical model was adapted for the existing Cleanergy Stirling engine, to evaluate the possibilities of this one engine for waste heat recovery. This paper also deals with application options and individual parameters that affect the efficiency of this Stirling engine for waste heat recovery. The analysis showed that this kind of engine is capable of recovering and utilizing heat above 300 °C, which determines its possible use with solar energy

Landfill Gas Enrichment Impact at Net Caloric Value

Rising use of renewable energy sources has brought many new challenges and use of many unusual energy resources. These resources are often of lower quality, a by-product or simple waste. Landfill gas is one of resources with lower quality and unwanted elements, as sulphur derivatives. After chemical or another treatment, the gas can be used in any burning facility. This article presents numerical model, which deals with simulation of enrichment process for landfill gas and subsequent use in heat source, with simple gas burner. The final gas is simulated as gas mixture, with different components portions

The Impact of Bark Content of Wood Biomass on Biofuel Properties

Woody biomass is an abundant, renewable energy source. Forest residue is the fraction remaining after harvest and the outtake of wood timber, including tree tops and bark. Compared with the wood portion, bark has a wide variation of ash content. Wood usually has a relatively low ash content, while bark has considerably higher ash content, which may generate clinker in the furnace and thereby tends to create more demand for maintenance. High ash content also generates more particulate emissions. Different types of bark were studied in the present work in terms of their effect on energy content, moisture, and ash content. The ash content of three different samples (Norway spruce, birch, and European beech) were measured at 550 and 815 °C. The results showed the impact of bark content on all parameters, in particular the calorific value and ash content. The ash content increased with increasing bark content. The addition of 1% bark content resulted in increases of ash content in the range 0.033 to 0.044%

Optimization of Construction Parameters of a Floor Convector

The paper deals with optimization of construction parameters of a floor convector with natural convection. Intensification of heat transfer from the floor convector with an objective to achieve the highest possible thermal performance of the floor convector was performed by CFD method and criterion equations at boundary conditions, like ambient temperature 20ºC and the temperature of the heating medium 75/65°C in thermostatic chamber