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The paper aims to undertake coal–water suspension combustion, in air and in fluidised bed conditions. Fluidised bed conditions are the best to efficiently and ecologically use fuel. Combustion technologies using coal–water fuels create a number of new possibilities for organising combustion processes so that they fulfil contemporary requirements. The aim of the process was to show how the specificity of combustion of coal–water suspensions in the fluidised bed changes the kinetics of the process, compared to combustion in the air stream. Changes of the surface and the centre temperature and mass of the coal suspension during combustion, and evolution of fuels during process are presented in the paper.

Experimental character of the research required the research stand preparation, as well as working out of the measurements methodology (Kijo-Kleczkowska, 2010). The research stand (Figure 1a) was made of ceramic blocks in which the quartz pipes were put. The heating element of the stand comprised three heating coils of 2.0 kW. Each heater was placed in small quartz tubes. These tubes were built into the quartz tube which was thermally insulated by fibre material Al₂O₃ and which was covered with steel sheet. Combustion chamber constituted the quartz pipe, which was additionally insulated thermally, to keep the necessary temperature of the entering gas and to reduce the heat loss. The compressed air was transported to the quartz tube through the electro-valve, the control valve and the rotameter. This study stand allowed for the comparison of the combustion process of coal–water suspensions, in air and in fluidised bed conditions. To study in the fluidised bed, quartz sand was used. Depending on the velocity of air inflowing from the bottom of the bed, different bed characteristics were obtained – from bubble – to circulating-beds. The fumes were removed outside by means of a fan fume cupboard. To regulate the temperature inside the combustion chamber, the Lumel microprocessor thermoregulator was applied. The regulator controlled the work of tri-phase Lumel power controller supplying the main heating elements (gas heater) allowing to measure the actual temperature with accuracy of measurements to 20°C. The temperature measurements in the combustion chamber were carried out by means of the thermocouple NiCr-NiAl. To establish the centre and surface temperature and mass of the fuel, a special instrument stalk was constructed (Figure 1b). It had two thermocouples PtRh10-Pt, placed in two thin quartz tubes connected to the scale. One of the thermocouples was located inside the fuel, while the other served as a basket which was to support the fuel. It also touched the surface of the fuel. The thermocouples were connected to the computer to record the experimental results. The essential stage of the preliminary work was to make out a suspension, which was a mixture of fuel dust (hard coal dust or dried coal-sludge dust) and water. To produce the suspension it was necessary to prepare fuel dust after grinding and sifting it, and then adding water, to obtain a suspension moisture of 20, 35 or 50 per cent. The hard coal was applied in the research. The analysis of fuel dust (in air-dry state) is shown in Table I. The testing of the porosity of fuel was made with mercury porosimetry, carried out in the Pascal 440 apparatus, applying pressure from 0.1 to 200 MPa. This method involves the injection of mercury into the pores of the fuel, using high pressures (Kijo-Kleczkowska, 2010).

1. Under experimental conditions, during combustion in the fluidised bed, intensive heating of the suspension is observed in the initial stage of the process, followed by the removal of heat from the suspension by the contacting quartz material, leading to lowering of the average fuel temperature and extension of the combustion time, compared to the process carried out in air. 2. Measurements using mercury porosimetry enable the identification of the change of suspension porosity. 3. Devolatilisation and combustion of volatiles lead to an increase in the pores’ size in the fuel and their coalescence. 4. Combustion of fuel leads to the development of cracks in the suspension, and its structure changes under the influence of temperature. Cracks are caused by the formation of thermal stresses inside the fuel. 5. Under experimental conditions, suspension combustion in the fluidised bed causes an increase in volume participation of pores, with larger sizes of pores (3,500-5,000 nm), compared to combustion in the air.

The paper undertakes the evolution of suspension fuel, made of a hard coal and a coal-sludge, during combustion in air and in the fluidised bed.

The main purpose of polymeric mixtures manufacturing is wish to eliminate or reduce drawbacks which polymers are characterised by and also to strive for reduction of the price of expensive polymers with particular very precious properties by mixing them with cheaper polymers but without significant deterioration of their properties. In the work some investigation results have been presented for PA6 which is miscible in viscoelastic state with polymer, with ability to create physical bounds with substances of inorganic as well as organic origins. For this purpose, polyvinylpyrrolidone (PVP) has been used with law molecular weight (10 ± 2,5 thousand). The functionalactive material was prepared with sharp tuning sorption ability across physical modification polycapramide mixed from bipolar polyvinylpyrrolidone in batch – free state, which characterises high ability complex. In the paper, some results of chosen properties of PA with the addition of polyvinylpyrrolidone (PVP) have been presented. In chance of mixing PA6 with PVP forms solution PVP in PA6, to which proper are large intermolecular influence, in this case hydrogen bond. It is possible to foresee that under the influences of large tangent stresses and intermolecular interaction colloidal solution PVP in PA forms with sure homogeneity, after cooling of it the inversion of winding phases is not noticeable In the mixtures on the basis of such polymers the intermolecular interactions occur, and they differently influence parameters of the modified materials. Conducted investigations have proved opportunity of physical modification of PA6 during mixing, in viscoelastic state, with polyvinylpyrrolidone. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.

For examinations, the following mixtures were made out: PA 99%/PVP 1%, PA 98%/PVP 2%, PA 90%/PVP 10%. Making mixtures out was begun with weighing elements out on numerical Sortorius AG GO TTINGEN scales and CAS MODEL: SW-1 (PA, PVP). Next elements of mixture were mixed with themselves mechanically. The process of drying was carried out in the ZELMET drier with the thermal kc-100/200 chamber in the temperature 80 °C for 12 h. The process of mixing up was carried out in the arrangement plasticising injections moulding machine of the voluted KRAUSS MAFFEI company KM 65-1600C1 (D screw = 30 mm and the L = 27D, the nozzle about d = 4 mm and the l = 2d) at the following parameters: is the nozzle temperature 230 °C, the speed of turnovers of the screw 210 obr/min. Granulated product of mixtures were get on the rotor grinder. Samples for examinations were made on the computer-operated injection moulding machine of type of KM 65-1600C1 of the KRAUSS MAFFEI company. The conditions which complement the homogeneity of a mixture – these include mixing processes with high shear stresses with the range of temperatures for viscoelastic state for the individual polymers. Such conditions are met by multiple mixing in the injection machine cylinder with extended perpetual screw length (L/D = 25 ÷ 42). Permanent conditions of injecting samples for the research on physical properties were the following: nozzle temperature – 230°C; worm area I temperature – 190°C; worm area II temperature – 210°C; worm area III temperature – 230-245°C, mould temperature 40°C, injection pressure – 60 MPa, clamping time – 5 s, cooling time – 30 s The research on chosen physical properties of getting polymer materials was carried out: hardnesses on hardness testing machine, impact resistance by Charpy’s method, mechanical properties while tension over the endurance machine the INSTON with tension speed of 90 mm/min, softening point by Vicat’s method was determined using testing machine type HAAKE N8, the investigation of DSC method and DMTA method using testing machine type Netzsch, water absorbing power test. The research on the structure was also carried out on the optical microscope type NIKON ECLIPSE E200.

In the paper, for the physical modification of PA 6, the polyvinylpyrrolidone (PVP) – amorphous polymer which is capable of ionisation and creation of complexes with the transition of the charge with many electrophilic compounds and also proton donors have been used. PVP does not change into the viscoelastic state but it is easily soluble in organic and inorganic solvents and the best in water. Its characteristic is high sorption capacity. As a result of ionisation changes PVP preserve the conformation changes. In case of mixing of polar PA6 polymers with PVP, a PVP solution is being created in PA, to whom big intermolecular interactions are proper for, in it hydrogen bonds. Reducing of polarity occurs of both polymers as a result of hydrogen bonds in created macromolecules. Macromolecule so they are interfering easily in fused condition creating the mixture about reliable homogeneity. An effect is applying to mixing with PA6 in case of dissolving PVP in the PA6 stop under the influence of big adjacent tensions in screw extruder what is calling changes of the supermolecular structure and properties of the material after chilling of stop in the form during injecting. The resultant homogeneous mixture is marked by one reflex narrowed in comparison with output PA6 of melting visible on DSC thermogram with moving to the page of higher tmmax temperatures. PA6/PVP mixtures are also providing effects of examinations about the homogeneity with DMTA method which shows results that the mixture is marked by one reflex of mechanical losses on the plot from (T_g) from the maximum at bigger than PA6 T_g (about 10 ÷ 15°C), and it is possible at the same time to reason that the mixture has not very thick frictional network as a result of the exchange of intermolecular bonds what is displayed itself in the increase in T_g intensity. The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power.

The results of investigations show that PA with PVP additions create more stable material with visible homogeneity (due to strong intermolecular interactions) which is characterised by satisfactory mechanical properties which insignificantly differ from PA6 properties, but which shows higher deformability and sorptive power. The modified polymer has dielectric properties and a reduced susceptibility to water absorption. It can be used as an insulation material, in all industrial sectors, including the energy sector.

The issues concerning the prediction of changes in properties of polymer materials as a result of adding reinforcing fibers are currently widely discussed in the field of polymer material processing. This paper aims to present strengths and weaknesses of composites based on polymer materials strengthened with fibers. It touches upon composite cracking at the junction of a matrix and its reinforcement. It also discusses the analysis of changes in properties of chosen materials as a result of adding reinforcing fibers. The paper shows improvement in the strength of polymer materials with fiber addition, which is extremely important, because these types of composites are used in the aerospace, automotive and electrical engineering industries.

Comparing the properties of matrix strength with fiber properties is practically impossible. Thus, fiber tensile strength and composite tensile strength shall be compared (González et al., 2011): tensile (glass fiber GF) = 900 [MPa], elongation ΔL≈ 0; yield point (polyamide 66) = 70−90 [MPa], elongation Δ[%] = 3,5-18; tensile (polyamide 66 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 66 + 30% GF) = 190 [MPa], elongation Δ[%] ≈ 0; yield point (polyamide 6) = 45-85 [MPa], elongation Δ[%] = 4-15; tensile (polyamide 6 + 15% GF) = 80-125 [MPa], elongation Δ[%] ≈ 0; tensile (polyamide 6 + 30% GF) = 95-130 [MPa] elongation Δ[%] ≈ 0. Comparison of properties of selected polymers and composites is presented in Tables 1−10 and Figures 1 and 2. The measurement methodology is presented in detail in the paper Kula et al. (2018). The increase in fiber content (to the extent discussed) leads to the increase in yield strength stresses and hardness. The value of yield strength for polyamide with the addition of fiberglass grows gradually with the increase in fiber content. The hardness of the composite of polyamide with glass balls increases together with the increase in reinforcement content. The changes of these values do not occur linearly. The increase in fiber content has a slight impact on density change (the increase of about 1 g/mm³ per 10 per cent).

The use of polymers as a matrix allows to give composites features such as: lightness, corrosion resistance, damping ability, good electrical insulation and thermal and easy shaping. Polymers used as a matrix perform the following functions in composites: give the desired shape to the products, allow transferring loads to fibers, shape thermal, chemical and flammable properties of composites and increase the possibilities of making composites. Fiber-reinforced polymer composites are the effect of searching for new construction materials. Glass fibers show tensile strength, stiffness and brittleness, while the polymer matrix has viscoelastic properties. Glass fibers have a uniform shape and dimensions. Fiber-reinforced composites are therefore used to increase strength and stiffness of materials. Polymers have low tensile strength, exhibit high deformability. Polymers reinforced by glass fiber have a high modulus of elasticity and therefore provide better the mechanical properties of the material. Composites with glass fibers do not exhibit deformations in front of cracking. An increase in the content of glass fiber in composites increases the tensile strength of the material. Polymers reinforced by glass fiber are currently one of the most important construction materials and are widely used in the aerospace, automotive and electro-technical industries.

The paper presents the test results for polyethylene composites with 25 per cent and 50 per cent filler coming from recycled car carpets of various car makes. The tests included using differential scanning calorimetry, testing material hardness, material tensile strength and their dynamic mechanical properties.