Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 6
items per page: 25 50 75
Sort by:

Abstract

An attempt was made to determine the vertical momentum and heat exchange in the near-ground atmosphere layer in the specific conditions of a sub-Antarctic island. For this purpose, some of the results of the measurements of temperature and wind speed carried out at the levels 10, 2, 0.5 and 0.05 m, during the IVth Antarctic Expedition of the Polish Academy of Sciences in March 1980, were used. The vertical gradients of the two elements and the wind stress and the heat flux in the layers under study, were calculated.
Go to article

Abstract

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.
Go to article

Abstract

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.
Go to article

Abstract

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
Go to article

Abstract

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.
Go to article

Abstract

Cyanobacterial and algal blooms lead to the deterioration of freshwater ecosystems but also generate technical problems in water management in the industry. Power plants often use freshwater lakes and reservoirs as a source of cooling water and in the case of cogeneration stations (combined heat and power) also as a source of agents for heating energy distribution. A preliminary research in one of the heat and power stations in eastern Poland which uses water from suffering with algal blooms reservoir was carried out in April 2011. The study was focused on the changes in the phytoplankton quantitative and qualitative structure as well as in basic physico- -chemical parameters along the water treatment line, which consists of several stages serving as sampling points (from the pump station to the purified water tank). The initial phytoplankton biomass in the reservoir was high (fresh biomass: 65.8 mg dm-3, chlorophyll a: 146.7 μg dm-3) with diatoms prevailing (98% of the total biomass) from which the most numerous were: Cyclotella comta and Aulacoseira granulata. After several stages of the purification process (sedimentation, biocide addition, flocculation, gravel filtering, ion exchange) the water still consisted a considerable amount of algae (fresh biomass: 2.48 mg dm-3, chlorophyll a: 6.0 μg dm-3). However, the final biomass in purified water tank (after reversed osmosis process) was very low (fresh biomass: 0.03 mg dm-3, chlorophyll a: 0.1 μg dm-3). Results had shown that high algal biomass in the water used in power generation plant is difficult to remove and consequently requires considerable technical (thus also economical) efforts to adjust the water for the industrial use.
Go to article

This page uses 'cookies'. Learn more