CO, NO, NO2 and dust concentrations from combustion of deciduous wood (birch, beech, lime-tree) logs and pellets in two heating boilers (15 and 25 KW), situated in a heat station were investigated. Time dependences of pollutant concentrations as well as the impact of temperature in the combustion chamber and oxygen concentration on pollutant concentrations were presented. Pollutant emission indices have been estimated.
Tests for combustion of hay and sunflower husk pellets mixed with wood pellets were performed in a horizontal-feed as well as under-feed (retort) wood pellet furnace installed in boilers with a nominal heat output of 15 and 20 kW, located in a heat station. During the combustion a slagging phenomenon was observed in the furnaces. In order to lower the temperature in the furnace, fuel feeding rate was reduced with unaltered air stream rate. The higher the proportion of wood pellets in the mixture the lower carbon monoxide concentration. The following results of carbon monoxide concentration (in mg/m3 presented for 10% O2 content in flue gas) for different furnaces and fuel mixtures (proportion in wt%) were obtained: horizontal-feed furnace supplied with hay/wood: 0/100 - 326; 30/70 - 157; 50/50 - 301; 100/0 - 3300; horizontal-feed furnace supplied with sunflower husk/wood: 50/50 - 1062; 67/33 - 1721; 100/0 - 3775; under-feed (retort) furnace supplied with hay/wood: 0/100 - 90; 15/85 - 157; 30/70 - 135; 50/50 - 5179; under-feed furnace supplied with sunflower husk/wood: 67/33 - 2498; 100/0 - 3128. Boiler heat output and heat efficiency was low: 7 to 13 kW and about 55%, respectively, for the boiler with horizontal-feed furnace and 9 to 14 kW and 64%, respectively, for the boiler with under-feed furnace.
The impact of the fuel feeding mode (continuous or periodic with different stand-by/operation time ratios) on carbon monoxide (CO) and nitrogen oxides (NO, NOx) concentration values in the flue gas was analysed for coniferous wood pellet firing. Experiments were performed in a 25 kW water boiler equipped with an over-fed wood pellet furnace located in a full scale heat station simulating real-life conditions. Influence of oxygen concentration and temperature in the combustion chamber on carbon monoxide and nitrogen oxide concentrations was presented in diagrams. Dust and hydrocarbon concentrations were also monitored. It was concluded that the commonly used periodic fuel supply does not necessarily cause a significant increase of carbon monoxide concentration, as compared to the continuous fuel feeding mode. Continuous fuel supply can even induce higher carbon monoxide concentrations when fuel mass stream is not chosen properly. Each time new fuel type is used in a specific furnace, one should perform experiments to determine the adequate settings (stand-by/operation time ratio, fuel mass streams, air stream) to obtain the optimal, lowest possible emission for a certain boiler heat output
It can be expected that there is a considerable correlation between combustion air flow rate and the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas. The influence of temperature and oxygen concentration in the combustion zone on the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas, for high and low combustion air flow, was analysed. Oxygen concentration for which the concentration of carbon monoxide is the lowest was determined, as well as the mutual relation between carbon monoxide and nitrogen oxide concentration.
A new method for measurement of local heat flux to water-walls of steam boilers was developed. A flux meter tube was made from an eccentric tube of short length to which two longitudinal fins were attached. These two fins prevent the boiler setting from heating by a thermal radiation from the combustion chamber. The fins are not welded to the adjacent water-wall tubes, so that the temperature distribution in the heat flux meter is not influenced by neighbouring water-wall tubes. The thickness of the heat flux tube wall is larger on the fireside to obtain a greater distance between the thermocouples located inside the wall which increases the accuracy of heat flux determination. Based on the temperature measurements at selected points inside the heat flux meter, the heat flux absorbed by the water-wall, heat transfer coefficient on the inner tube surface and temperature of the water-steam mixture was determined.
The aim of the study was to evaluate the effect of pre-sowing seed stimulation of Thuringian Mallow (Lavatera thuringiaca L.) with He-Ne laser light of different exposure times on the crop yield as well as on energetic parameters such as calorific value and combustion heat. Seeds were subjected to laser light with an exposition time of 0, 1, 5, 10, 15 and 30 minutes. Measurements were carried out independently on mature plants from the first and second vegetation year. The results varied between the samples, which indicated possible impact of laser radiation on the resultant weight and calorific value of various experimental combinations. For plants from the second vegetation year the statistical differences in calorific value, combustion heat and crop mass were found between samples characterized by different exposition times: between sample irradiated for 30 min (L30) and 1 min (L1) as well as between sample L30 and sample irradiated for 5 minutes (L5). For plants after the first vegetation year the statistically significant differences in calorific value and combustion heat were found for sample with exposition time of 15 minutes (L15) and control sample, for sample L15 and sample L5 as well as between samples L15 and L30. For all the samples from the second vegetation year the increase in combustion heat and calorific values were detected as compared to control. Thus, after the application of certain parameters of laser radiation to the processing of seeds, the plant can be more useful for energetic purposes through more efficient crop.
The author has developed and patented several types of gas cupola furnaces, which, due to replacing coke with gas, do not emit carbon monoxide, sulfur dioxide and coke dust. The author has defined the optimal modes of gas-and-air mixture combustion, i.e. the optimal coefficient of air discharge and gas mixture escape speed in melting cast iron. It has been experimentally proved that from the point of view of obtaining the maximum temperature, the optimal was the process with some lack of air, i.e. with α = 0.98. The results of metallurgical studies used in the article allowed to develop an optimal structure of the gas cupola furnace with a heterogeneous refractory filling, and to establish the optimal composition of the filling. For the first time the optimal composition of the filling is given: 40% of chamotte, 30% of high-alumina refractory, 30% of electrode scrap. It has been noted that when gas cupola furnaces were used, the main environmental advantage was the reduction of dust emission into the atmosphere, CO and SO2 content.
Investigations were carried out to evaluate the performance of a low heat rejection (LHR) diesel engine consisting of different versions, such as ceramic coated cylinder head engine-LHR-1-Air gap insulated piston and air gap insulated liner-LHR-2- and Ceramic coated cylinder head, air gap insulated piston and air gap insulated liner -LHR-3 with degrees of insulation with normal temperature condition of linseed oil with varied injection pressure. Performance parameters were determined at various magnitudes of brake mean effective pressure. Pollution levels of smoke and oxides of nitrogen (NOx) were recorded at the peak load operation of the engine. Combustion characteristics of the engine were measured with TDC (top dead centre) encoder, pressure transducer, console and special pressure-crank angle software package. Conventional engine (CE) showed deteriorated performance, while LHR engine showed improved performance at recommended injection timing of 27 degrees bTDC and recommend injection pressure of 190 bar with vegetable oil operation, when compared with CE with pure diesel operation. Peak brake thermal efficiency increased by 14%, smoke levels decreased by 10% and NOx levels increased by 30% with LHR engine at an injection pressure of 270 bar when compared with pure diesel operation on CE at manufacturer's recommended injection timing.