Waste heat potentials in the drying section of the paper machine in Umka Cardboard Mill

This paper deals with methods for calculation of potentials of waste heat generated in paper/board production process. For that purpose, the material and heat balance of the cardboard machine at Umka Cardboard Mill has been determined. Field measurements were conducted in order to define the unknown values of process parameters used for calculation in the balance equations and modelling. The focus was given to the cardboard drying section, which consumes most of the energy supplied to the machine. Additional aim of the work presented in the paper was to evaluate the specific energy consumption and the thermal efficiency of all individual energy units within the machine's drying section. The results indicate two main sources of waste heat: waste heat released to the atmosphere with the discharge air from the present waste heat recovery system (14,380 kW), and waste heat released in the hall from the machine and extracted by the hall ventilation system (4,430 kW). Waste heat from both sources is characterized by fairly low temperatures 58-75°C and fairly high moisture content (30-40 g/kg). The specific heat consumption and specific steam consumption (consumption per tonne of produced cardboard) of the machine was 1,490 kWh/t and 1.4 t/t, respectively. The thermal efficiency of drying section and coating drying section was 55.6% and 33.6%, respectively. All these figures imply necessity for further waste heat utilization with the aim of improving the efficiency of energy use

Investigation of co2 diluted methane and propane swirling premixed flames using ch* chemiluminescence imaging

Utilization of hydrocarbon gaseous fuels, such as biogas, landfill gas and others, is a valuable contribution to sustainable energy production and climate changing control. The presence of CO2 in these gases decreases heat of combustion, flame temperature, flame speed and can induce flame blow-off and combustion instabilities. In order to better understand the problem, flame geometry and location was investigated using chemiluminescence (CH*) imaging technique. Combustion took place in a purposely built, lean, premixed, unconfined swirl burner, fueled by methane and propane diluted with CO2. The fuel type, air-to-fuel equivalence ratio and CO2 content were chosen as the independent variables. The CH* imaging by means of a commercial CCD camera, fitted with an optical filter, was used for flame investigation. The analysis of images showed that the CH* emission intensity, flame geometry and location were remarkably affected by the fuel type and the air-to-fuel equivalence ratio, while the CO2 dilution was of minor importance

Size distribution of agglomerates of milk powder in wet granulation process in a vibro-fluidized bed

Results of experiments on the influence of technological parameters (intensity of vibration, granulation of the liquid feed, temperature of fluidization agent) on the change of size distribution, as well as mass mean diameter of the milk powder particles subjected to the wet granulation process (agglomeration) in a vibro-fluidized bed granulator are shown in this paper. Using water as a granulation liquid and air as a fluidization agent, it was found that mass mean diameter increases with increase of water feed, intensity of vibration, and decrease of air temperature. Increasing the intensity of vibration and decreasing the air temperature, primarily induces the increase of the dimensions of the initial nuclei. This can be explained on the basis of different influences that these changes (velocity of particle motion, intensity of particle collision, drying rate) have on the coalescence of particles with smaller and/or bigger dimensions

Investigation of co2 diluted methane and propane swirling premixed flames using ch* chemiluminescence imaging

Utilization of hydrocarbon gaseous fuels, such as biogas, landfill gas and others, is a valuable contribution to sustainable energy production and climate changing control. The presence of CO2 in these gases decreases heat of combustion, flame temperature, flame speed and can induce flame blow-off and combustion instabilities. In order to better understand the problem, flame geometry and location was investigated using chemiluminescence (CH*) imaging technique. Combustion took place in a purposely built, lean, premixed, unconfined swirl burner, fueled by methane and propane diluted with CO2. The fuel type, air-to-fuel equivalence ratio and CO2 content were chosen as the independent variables. The CH* imaging by means of a commercial CCD camera, fitted with an optical filter, was used for flame investigation. The analysis of images showed that the CH* emission intensity, flame geometry and location were remarkably affected by the fuel type and the air-to-fuel equivalence ratio, while the CO2 dilution was of minor importance

Analysis of the performance of a low-power atmospheric burner for gas appliances for households and their impact on the emission and stability of the burner

The paper presents results of theoretical numerical research dealing with CO and NOx emission performed in the process of optimization of the performance of low-power atmospheric burners. The theoretical part of this paper, whose main goals were better understanding of the complex issues of methodology and establishment of performance prediction and optimization of low-power atmospheric gas burner included numerical variation of independent parameters, such as burner geometry, the coefficients of primary and secondary air and different gaseous fuels including biogas. The findings of theoretically obtained performance prediction and optimization of atmospheric burners were experimentally investigated in purpose built test rigs for a number of variable parameters. The obtained results fully justified the proposed models of performance prediction and burner optimization

Analysis of the performance of a low-power atmospheric burner for gas appliances for households and their impact on the emission and stability of the burner

The paper presents results of theoretical numerical research dealing with CO and NOx emission performed in the process of optimization of the performance of low-power atmospheric burners. The theoretical part of this paper, whose main goals were better understanding of the complex issues of methodology and establishment of performance prediction and optimization of low-power atmospheric gas burner included numerical variation of independent parameters, such as burner geometry, the coefficients of primary and secondary air and different gaseous fuels including biogas. The findings of theoretically obtained performance prediction and optimization of atmospheric burners were experimentally investigated in purpose built test rigs for a number of variable parameters. The obtained results fully justified the proposed models of performance prediction and burner optimization

Biomass gasification with chp production a review of the state-of-the-art technology and near future perspectives

This paper is a review of the state-of-the-art of biomass gasification and the future of using biomass in Serbia and it presents researches within the project "The Development of a CHP Plant with Biomass Gasification". The concept of downdrafi demonstration unit coupled with gas engine is adopted. Downdrafi fixed-bed gasification is generally favored for CHP, owing to the simple and reliable gasifiers and low content of tar and dust in produced gas. The composition and quantity of gas and the amount of air are defined by modeling biomass residues gasification process. The gas (290-400 m(3)/h for 0.5-0.7 MW biomass input) obtained by gasification at 800 degrees C with air at atmospheric pressure contains 14% H-2, 27% CO, 9% CO2, 2% CH4, and 48% N-2, and its net heating value is 4.8-6 MJ/Nm(3). The expected gasifier efficiency is up to 80%. The review of the work on biomass gasification has shown that the development of technology has reached the mature stage. There are CHP plants with biomass gasification operating as demonstration plants and several gasification demonstration units are successfully oriented to biofuel production. No attempt has been made here to address the economic feasibility of the system. Economics will be the part of a later work as firmer data are acquired

Proračun posuda sa vazduhom za zaštitu cevovoda od hidrauličnog udara

Posude sa komprimovanim vazduhom mogu na efektivan način da umanje pojavu prekomernog povišenja i smanjenja pritiska usled hidrauličnog udara u industrijskim cevovodima. U radu je prikazana pojednostavljena procedura za proračun zapremine posude koju zauzima vazduh i ukupne zapremine posude. U radu su date preporuke za pravilan izbor dimenzija ulaznog i izlaznog cevnog priključka na posudi čime se može minimizirati njena zapremina

Negative modulation of alpha(5) GABA(A) receptors in rats may partially prevent memory impairment induced by MK-801, but not amphetamine- or MK-801-elicited hyperlocomotion

Reportedly, negative modulation of alpha(5) GABA(A) receptors may improve cognition in normal and pharmacologically-impaired animals, and such modulation has been proposed as an avenue for treatment of cognitive symptoms in schizophrenia. This study assessed the actions of PWZ-029, administered at doses (2, 5, and 10 mg/kg) at which it reached micromolar concentrations in brain tissue with estimated free concentrations adequate for selective modulation of alpha(5) GABA(A) receptors, in three cognitive tasks in male Wistar rats acutely treated with the noncompetitive N-methyl-D-aspartate receptor antagonist, MK-801 (0.1 mg/kg), as well in tests of locomotor activity potentiated by MK-801 (0.2 mg/kg) or amphetamine (0.5 mg/kg). In a hormetic-like manner, only 5 mg/kg PWZ-029 reversed MK-801-induced deficits in novel object recognition test (visual recognition memory), whereas in the Morris water maze, the 2 mg/kg dose of PWZ-029 exerted partial beneficial effects on spatial learning impairment. PWZ-029 did not affect recognition memory deficits in social novelty discrimination procedure. Motor hyperactivity induced with MK-801 or amphetamine was not preventable by PWZ-029. Our results show that certain MK-801-induced memory deficits can be ameliorated by negative modulation of alpha(5) GABA(A) receptors, and point to the need for further elucidation of their translational relevance to cognitive deterioration in schizophrenia