Impact of ignition technique on pollutants emission during the combustion of selected solid biofuels

Nowadays, heating using wood, briquettes, or pellets is a curious replacement to fossil fuels such as coal, oil, or gas. Unfortunately, the combustion of biofuels, especially in low-power boilers with unstable operating conditions, releases a lot of gas pollutants (e.g., carbon monoxide (CO), nitric oxide (NO), and various organic compounds) that are usually generated due to the incomplete product combustion. The combustion of biofuel in grate boilers with top-down ignition is a new approach, popular in society (mainly used for coal fuels), which improves the combustion process and reduces the amount of pollutants emitted. This study evaluated the impact of ignition techniques on the emission level of gas pollutants during the combustion of wood logs, briquettes, and pellets of pine in grate-based charging boilers. The combination of top ignition mode with pinewood logs allowed us to achieve a reduction of 6% in CO and sulfur dioxide (SO2) emission into the atmosphere. However, the combination of top-down ignition mode with pellets and briquettes produced, in fully operational conditions, 1- to 18-fold higher levels of CO and SO2 respectively, than bottom-up ignition, after an initial period of low level CO and SO2 emissions. During the tests (mainly with ignition from top), substantial emissions of NO were observed of up to 400 mg m-3 at 10% O2. Therefore, further research is required to decrease emission related to the content of nitrogen in biomass. In this respect, research of impact on the combustion temperature of such emissions is needed

The research techniques for analysis of mechanical and tribological properties of coating-substrate systems

W artykule przedstawiono techniki badawcze pozwalające na analizę właściwości zarówno mechanicznych, jak i tribologicznych cienkich powłok nanoszonych na elementy maszyn pracujących niejednokrotnie w ciężkich warunkach. W Katedrze Konstrukcji i Eksploatacji Maszyn w Akademii Górniczo-Hutniczej w Krakowie studenci studiów magisterskich na kierunku mechanika i budowa maszyn w ramach fakultetu tribologia odbywają laboratoria, podczas których poznają między innymi nowe techniki badań cienkich powłok nanoszonych metodami PVD i CVD. Obejmują one analizę mikro-, nanotwardości oraz modułu Younga przy użyciu techniki instrumentalnej indentacji. Studenci wykonują także testy zarysowania, dzięki którym przeprowadzają pomiar adhezji cienkich powłok i warstw wierzchnich do podłoży. Właściwości tribologiczne układów powłoka-podłoże są badane różnymi technikami, głównie w styku skoncentrowanym kula-tarcza i rolka-klocek oraz środowisku silnie ściernym tarcza-kula.The article presents research techniques for the analysis of both mechanical and tribological properties of thin coatings applied on highly loaded machine elements. In the Institute of Machine Design and Exploitation, AGH University of Science and Technology students of the second level of Mechanical Engineering study tribology attending laboratory class. Students learn on techniques for mechanical and tribological testing of thin, hard coatings deposited by PVD and CVD technologies. The program of laboratories contains micro-, nanohardness and Young's modulus measurements by instrumental indentations and analysys of coating to substrate adhesion by scratch testing. The tribological properties of the coating-substrate systems are studied using various techniques, mainly in point contact load conditions with ball-on-disc and block-on-ring tribomiters as well as using ball cratering method in strongly abrasive suspensions

Impact of persulfate and monopersulfate on physico-chemical properties of the activated sludge

Ze względu na wzrastającą ilość osadów ściekowych wymagających zagospodarowania nieustannie poszukuje się nowych metod pozwalających na ich lepsze kondycjonowanie. Do takich metod należy zaliczyć różnego rodzaju sposoby dezintegracji osadów. W podjętych badaniach starano się określić wpływ chemicznej dezintegracji przy pomocy termicznie aktywowanego nadsiarczanu sodu (PDS) i mononadsiarczanu potasu (MPS) na wybrane własności sedymentacyjne i fizykochemiczne osadu ściekowego. W badaniach użyto dawek reagentów PDS i MPS: 0,2; 0,4; 0,6; 0,8 i 1% objętościowych, które aktywowano termicznie w temperaturze 60 i 80ºC przez 30 minut. Wpływ analizowanych substancji na osad czynny starano się wykazać na podstawie zmian wybranych parametrów, takich jak: mętność, uwolniona/rozpuszczona materia organiczna (wyrażone jako rChZT), indeks objętościowy osadu (I.O.O.) i indeks gęstości osadu (I.G.O.). Pod wpływem działania PDS i MPS mętność cieczy nadosadowej zmalała odpowiednio o 90 i 85%. Wraz ze wzrostem dawki reagentów zaobserwowano wzrost wartości rChZT, będącego wskaźnikiem uwolnionej w trakcie dezintegracji materii organicznej. Wartość rChZT w cieczy nadosadowej przy zastosowaniu PDS i MPS wzrosła odpowiednio o 41 i 77%. Zaobserwowano również zmniejszenie indeksu objętościowego osadu (I.O.O.) przy zastosowaniu temperatury aktywowania substancji dezintegrujących równej 80ºC oraz dawce tych substancji równej 1%. W przypadku MPS wartość indeksu objętościowego zmniejszyła się z 37,80 do 16,29 cm3/g po 30 minutach sedymentacji. Natomiast dla PDS nastąpił spadek wartości z 39,49 do 24,66 cm3/g w tym samym czasie.Due to the increasing amount of sewage sludge requiring management new methods which allow improving sludge conditioning are being sought incessantly. Such methods include different types of sludge disintegration processes. In the present study an attempt was made to determine the influence of thermally activated persulfate (PDS) and monopersulfate (MPS) on the sedimentation and physico-chemical properties of the waste activated sludge (WAS). In this study 0.2, 0.4, 0.6, 0.8, 1% doses of PDS and MPS were used, and they were activated at the temperature of 60 and 80ºC for 30 minutes. The impact of the analyzed substances on WAS was investigated on basis of changes of the selected parameters such as: turbidity, soluble chemical oxygen demand (rCOD), sludge volume index (SVI). Addition of PDS and MPS to the WAS caused decrease of turbidity of supernatant by 90 and 85%, respectively. When the doses of the reactants increased there was also an increase in the SCOD value, being an indicator of the organic matter released during the disintegration. The SCOD value in the supernatant increased with using PDS and MPS by 41 and 77%, respectively. There was also observed decrease of sludge volume index (SVI) after addition of temperature activated (80ºC) PDS and MPS. For highest dose of MPS, SVI decrease from 37.80 to 16.29 cm3/g after 30 min sedimentation. In contrast, for the PDS there was a decrease from 39.49 to 24.66 cm3/g at the same time

Correction: Experimental study of disc fertilizer spreader performance (Agriculture 2020, 10, 467)

The authors unintentionally missed the citation of the chapter by Hofstee J. W., Speelman L., Scheufler B. “1.4-Fertilizer Distributors” in the “CIGR Handbook of Agricultural Engineering— Volume III, Plant Production Engineering” edited by “The International Commission of Agricultural Engineering, Stout B.A. Texas A&M University U.S.A., Cheze B. Ministry of Agriculture Fisheries and Food France” and published by “American Society of Agricultural Engineers: St. Joseph MI, U.S.A.” in 1999, and thus they wish to apologize to the authors of the uncited work and to make the following corrections to [1]

Common greenhouse conditioning plants compared with versatile geothermal system in Ames, Iowa

Energy consumption is one of the most important factors related to profitability in greenhouse systems, and it is a factor in both financial considerations and environmental impacts. Competitiveness in the greenhouse industry is highly dependent upon the energy demand of heating systems. This paper focuses on the use of geothermal energy in agricultural sector. A ground source heat pump system was designed for a new greenhouse complex in Ames, Iowa. An accurate study of the external air temperatures, solar radiation, time, wind speed, and boundary conditions was conducted. Electrical and heating energy, and power demands were analysed. For the greenhouse design presented, the greatest power demand was 350 kW for heating and 620 kW for cooling. These values permitted the greenhouse to be maintained at the temperature of 16.7 ºC, when the external temperature ranged from -20 ºC to 30 ºC. An economic analysis was conducted considering only the energy demand cost, and this cost was compared with the equivalent energy cost of fuel oil and natural gas systems for heating and the equivalent energy cost of the fan and pad systems for cooling. For heating purposes, the economic analysis showed that the total energy demand cost over the nine years of using a closed-loop GWHP was around 120,000 USD, whereas the fuel oil system was 364,000 USD, and the natural gas system was 253,000 USD. This yields cost savings of 67 % and 53 %, respectively. For the cooling purposes, the economic analysis is inconsistent, and the fact, the energy cost difference between the closed-loop ground source heat pump cooling system and fad and pad systems is huge, 83,000 USD for closed-loop ground source heat pump cooling and around 5,200 USD for the fan and pad system energy in nine years

Tribology of carbon coatings at elevated temperature

W pracy przedstawiono wyniki badań mechanicznych i tribologicznych powłok węglowych a-C, a-C:H i a-C:N. Właściwości tribologiczne takich powłok wciąż nie są dostatecznie rozpoznane, zwłaszcza w przypadku analiz prowadzonych w podwyższonych temperaturach. W ramach pracy analizowano właściwości mechaniczne – twardość i moduł sprężystości oraz właściwości tribologiczne – wskaźnik zużycia i współczynnik tarcia w temperaturze 20ºC i 300ºC. Najtwardszą z powłok okazała się powłoka a-C – 17 GPa, a najmiększą a-C:H – 7GPa. Testy tribologiczne w temperaturze pokojowej wykazały, że współczynnik tarcia jest najmniejszy dla powłoki a-C, a najwyższy dla a-C:N – odpowiednio m = 0,05 i 0,24. Najniższe wartość wskaźnika zużycia zmierzono także dla powłoki a-C. Natomiast w temperaturze 300ºC najlepszą okazała się powłoka uwodorniona a-C:H, dla której zużycie było tylko nieznacznie wyższe niż w temperaturze pokojowej, a współczynnik tarcia wynosił 0,04. Zużycie powłoki a-C:N jest 20-krotnie większe niż powłoki a-C:H, chociaż współczynnik tarcia w całym zakresie 20 000 cykli testu tribologicznego wynosił tylko 0,05. Natomiast powłoka a-C w warunkach przeprowadzanego testu została całkowicie zniszczona już po 7000 cykli.The paper presents the results of the mechanical and tribological coatings of carbon a-C, a-C:H and a-C:N coatings. The hardest coatings H = 17 GPa is a non-hydrogenated a-C coating, while the softest one is a-C:H - 7 GPa. Tribological tests performed at 20°C exhibited the lowest coefficient of friction 0.05 for the a-C coating. In a case of this coating, the lowest value of wear index was also measured. The hydrogenated and nitrogenated coatings have higher friction m = 0.14 and 0.24 respectively. However, the wear of these coatings was higher than for a-C, but it was still at low level comparing to typical ceramic coatings. In contrast, the hydrogenated a-C:H coating exhibited the best wear resistance at 300°C. The wear index was only 50% higher than at room temperature and the friction coefficient varied within the range of 0.03-0.05. The nitrogenated coating a-C:N has 20 times higher wear than the a-C:H coating, although the friction coefficient was only 0.05 over the whole test duration – 20000 cycles. The best coating (a-C) at in room temperature was the worst at elevated temperatures. This coating was completely destroyed after 7000 cycles

The influence of digestate on the static strength of spring rapeseeds (Brassica napus var. arvensis)

Biogas production occurs during methane fermentation from organic substrates and the mass remaining after fermentation, containing organic matter and valuable minerals having regard to plant nutrition, forms the digestate, which could be useful for fertilizing purposes and very beneficial in the case of the fertilization of rapeseeds. This paper focuses on the use of two forms of fertilization of rapeseeds-digestate and mineral fertilizers-in order to reduce the compressive strength of rapeseeds. The object presents results of compressive strength tests of three rape varieties (Bios, Feliks, Markus). The uniaxial compression tests between two parallel planes were made using a Zwick/Roell Z005 testing machine. Comparative analyses for the analyzed variables were carried out applying parametric and non-parametric statistical tests. On the basis of the conducted research, it was found that the distribution of the increase in the force crushing Bios and Feliks rapeseed varieties in both forms of cultivation was proportional to the increase in their mass. However, with a relatively comparable mass of Bios cv. seeds, in the case of the digestate use, a stronger correlation was found between the seed pressing force and its mass than for the multi-component fertilizer, understanding the need to apply more force to crush the seeds for this form of cultivation. In the conducted tests, the average size of rapeseed diameters of all varieties and forms of cultivation ranged from 1.81-1.95 mm, which indicates their good suitability for industrial purposes