Glossary
Solid (carbon) residue
Moisture of solid (carbon) residue. The moisture content is determined by drying a fuel sample at a specific temperature and calculating the moisture content from the mass loss. This indicator is an important quality parameter, since an increased moisture content in the solid residue leads to a decrease in its heat of combustion, a decrease in flowability, freezing of coal in winter, and thereby reduces its cost. Fuel that has entered the combustion chamber is quickly dried, and the moisture contained in it turns into superheated water vapor. Part of the heat is spent on evaporation and overheating of moisture, as a result of which the temperature of the torch in the melting chamber decreases. This decrease in temperature can be very significant, since much more heat is spent on moisture evaporation than on heating, melting and partial ash evaporation.
The ash content of the solid (carbon) residue is determined by burning fuel (ashing) with free access of air and calcining the ash residue to constant weight at a certain temperature. Solid fuels always contain non-combustible mineral impurities, which include calcium, magnesium carbonates, gypsum, pyrite, and rare elements. When fuel is burned, the unburned part of mineral impurities forms ash, which, depending on its composition, can be refractory or low-melting, bulk or fused. Mineral impurities worsen the quality of coal, reduce the heat of combustion, and increase fuel consumption per unit of output.
The volatile component yield is defined as the difference between the weight and moisture loss on heating. Based on the values of the yield of volatile substances and the characteristics of the non-volatile residue, it is possible to roughly estimate the caking capacity of coals, as well as predict the behavior of the fuel in the technological processes of processing and propose rational combustion methods.
Calorific value - heat released after complete combustion of solid fuel in oxygen. The heat of combustion is the most important indicator of the quality of energy fuel and characterizes the heat value of the fuel.
Sulfur in the solid (carbon) residue is determined by X-ray fluorescence analysis. When fuels are burned, it is emitted in the form of SO2, polluting and poisoning the environment and corroding metal surfaces, and reduces the heat of combustion of fuels. The choice of use of fuels often depends on their total sulfur content.
The chemical composition of the solid (carbon) residue is determined by scanning electron microscopy with electron probe chemical analysis.
Pyrolysis gas
Determination of the qualitative (gas components) and quantitative (percentage) composition makes it possible to calculate the calorific value (heat of combustion) of the gas mixture and is carried out by the method of gas-liquid chromatography.
The heat of combustion is the most important characteristic of the energy potential and economic efficiency of the use of gaseous products of pyrolysis waste processing as fuel. The higher the calorific value of the fuel, the lower the fuel consumption.
Selection of a flue gas cleaning and neutralization system
Determination of solid particles
Determination of hydrochloride
Determination of hydrofluoride
Determination of sulfur dioxide
Determination of heavy metals
Determination of mercury
Determination of polycyclic aromatic carbons
Purification and clarification of used oils and substandard fuels
The selection of sorbents and the selection of their granulometric composition is of great importance in the development of methods for cleaning and clarifying waste oils and substandard fuels.
Granulometric composition - the relative content of particles of different sizes in a solid material, characterized by the yield as a percentage of the mass. To determine it, use the sieve method.
Liquid Products
Fractional composition is a defining characteristic when determining the scope of application of a pyrolysis liquid - a multicomponent mixture of hydrocarbons of various compositions.
In laboratory and industrial conditions, distillation is carried out at a constantly increasing boiling point. This allows the separation of liquid components into fractions, which are characterized by a certain temperature range (point of the beginning and end of boiling).
Atmospheric distillation of the pyrolysis liquid makes it possible to isolate the following fractions, which boil away at temperatures up to 350 ° C:
light fractions (petroleum, gasoline) - from the beginning of boiling to 140 ° С;
middle fractions (naphtha, kerosene, diesel) - 140 ° С to 350 ° С;
The study of the fractional composition of the pyrolysis liquid obtained in the process of processing waste (solid waste, plastic, automobile tires, etc.) makes it possible to assess the possibility of obtaining potential marketable products (solvents, motor fuels, similar to diesel and gasoline) and to determine their area of application.
2. Density is a physicochemical property of the fuel, showing the specific gravity, namely the amount of mass per unit volume.
By the density of the fuel, one can roughly judge its hydrocarbon composition, so paraffins have the lowest density, and naphthenic compounds have the highest density. The higher the content of heavy fractions in the fuel, the higher its density, and, accordingly, the more light fractions, the lower the density. In addition, the fuel density is also influenced by the percentage of high-octane components - alcohols and ethers.
3. The mass fraction of water is determined according to the method based on the quantitative distillation of water collected in the receiver-trap from the analyzed product. Water in pyrolysis liquid and fuels can be in free, emulsion and dissolved states (hygroscopic). The presence of water in the fuel is unacceptable, as ice crystals form at low temperatures, which can disrupt the supply of fuel to the engine. In addition, water is one of the causes of corrosion of fuel assemblies.
4. The content of mechanical impurities is to determine the mass of mechanical impurities retained by the filters when the test product is passed through them.
The presence of precision parts in the fuel equipment makes increased demands on the purity of fuels - they should not contain mechanical impurities, which are of greater hardness and cause increased wear of engine parts. Particularly harmful are impurities for high-pressure fuel pumps, pump-injectors, injectors.
5. The content of water-soluble acids and alkalis characterizes the corrosiveness of the fuel and is determined by extracting acids and alkalis from oil products with water or an aqueous solution of alcohol and determining the pH value of the aqueous extract with a pH meter.
The presence of water-soluble acids and alkalis is checked for their complete absence, since they are electrolytes and cause chemical corrosion. Corrosion products pass into fuel and clog filters and other fuel equipment.
6. Mass fraction of aromatic hydrocarbons is determined by treating the test product with sulfuric acid, which reacts with unsaturated and aromatic hydrocarbons.
This indicator allows you to control the content of aromatic hydrocarbons in the fuel, the chemical composition of which determines its main technological and environmental properties. The presence of aromatic hydrocarbons in gasoline fractions can increase the octane number and contribute to a more complete and uniform combustion of the air-fuel mixture. However, with their increased content in both gasoline and diesel fractions under the influence of high temperatures, aromatic hydrocarbons undergo oxidative transformations and are the main source of carbon deposits, also with an increased content of "aromatics", the yield of toxic products in exhaust gases increases, the emission of harmful nitrogen oxides also depends from the volume of aromatic hydrocarbons.
7. Test on a copper plate - an indicator that determines the corrosiveness of the fuel, depending on the total content of active sulfur compounds (mercaptans, hydrogen sulfide, free sulfur ) at elevated temperatures . The essence of the test is the effect of fuel on a clean polished copper plate for a given time and temperature.
The appearance on the plate of films or deposits of black, gray or dark brown color, or black dots, is a sign of the presence of free sulfur or active sulfur compounds in the fuel.
8. Determination of sulfur content is carried out by infrared spectroscopy. The presence of sulfur compounds in the fuel increases the toxicity of exhaust gases, both by increasing the concentration of sulfur oxides and particulate matter in them, and indirectly, by reducing the efficiency and reliability of modern exhaust gas composition control systems.
9. Flash point in a closed crucible is the lowest temperature of a volatile condensed substance at which vapors above the surface of the substance can flash in the air under the influence of an ignition source, however, stable combustion does not occur after removing the ignition source. Flash - rapid combustion of a mixture of vapor of a volatile substance with air, accompanied by a short-term visible glow.
Flash point should be distinguished both from the ignition temperature, at which the combustible substance is able to burn independently after the ignition source has stopped acting, and from the auto-ignition temperature, at which an external ignition source is not required to initiate a combustion or explosion.
10. The octane number is used as a rating scale for gasoline. This indicator characterizes the knock resistance of the fuel, i.e. the ability of the fuel to resist spontaneous combustion during compression. High octane values of gasoline indicate the absence or minimal presence of the possibility of detonation, as well as the fact that with a high compression ratio, the engine is able to develop more torque with the same amount of fuel consumed.
To determine the octane number, methods of indirect assessment of detonation resistance are used by physicochemical indicators and characteristics of a low-temperature reaction of gas-phase oxidation, simulating pre-flame processes. The octane number is determined by two methods - research and motor. The research method makes it possible to investigate the detonation resistance of the fuel in relation to the reference, the motor method determines the resistance of gasoline to detonation at maximum engine power in the mode of increased temperature.
11. The cetane index serves as a means of assessing the cetane number of diesel fuel (characteristic of the flammability of diesel fuel, which determines the delay period of the combustion of the working mixture (the time interval from fuel injection into the cylinder to the beginning of its combustion)). The higher the cetane number, the less the delay and the more calmly and smoothly the fuel mixture burns. The cetane index is determined by calculation. The essence of this method is to determine, according to standardized methods, the fuel density at a temperature of 15 ºС and temperatures at which 10 vol. %, 50 vol. % and 90 vol.% of the sample and the calculation of the cetane index from these data.
12. The qualitative and quantitative composition of the pyrolysis liquid is carried out by gas-liquid chromatography.
13. Determination of the resistance of rubbers to the action of a pyrolysis liquid is based on an assessment of the properties (weight, dimensions) before and after immersion in a test liquid at a given temperature and time and allows one to obtain information on the behavior of rubber products during operation in contact with a pyrolysis liquid.