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Combustion Characteristics Of Residues In Larix Gmelinii Plantation Slash

Posted on:2017-05-10Degree:MasterType:Thesis
Country:ChinaCandidate:H Y ZhaoFull Text:PDF
GTID:2283330491952052Subject:Forest Engineering
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Combustion is a complex proccesses of physical and chemical, its occurrence and development is random and not controllable. Larix gmelinii plantation slash is the main forest type of Daxinganling and Xiaoxinganling, it is different from other species due to its branches and stumps have lots of grease, after harvesting operations, illumination environment condition and ventilation are greatly improved, with the higher grease content factor the slash translate into inflammable very quickly, especially, the slash is highly vulnerable to forest fires during periods of windy dry seasons which leading to serious economic losses, accordingly, it is necessary to research slash combustion characteristic.This article introduces the basic theory of slash burning, which including combustion conditions, combustion process, the reach of combustion characteristics, and numerical calculation, etc. Arrangement combustion bed after the field researching, with wind speed, surface fuel moisture, temperature, slope as factors, design L9 (34). The experimental results show that the wind speed has a significant effect on the rate of fire spread and fire intensity, the two indicators will increase significantly with the increase of wind speed; The surface moisture content has obvious effects on the highest temperature, the rate of fire spread and fire intensity, which will decrease with the increase of surface moisture content; The field temperature has a significant effect on the maximum temperature, and the maximum temperature increases with the increase of the field temperature; Along with the increase of slope, the maximum temperature, fire spread speed and fire intensity strengthened; The highest temperature in the combustion process is about 498℃, the maximum average fire spread is 2.64×10-2m/s, the minimum is 1.64×10-2m/s, fire intensity up to 2857.98kW/m. By the comprehensive analysis of the results:the wind speed and surface fuel moisture are the main factors that affecting slash combustion, weight value is the biggest when the wind speed is 5m/s, surface fuel moisture is 10%.The lowest rating of fire when slash all out and fuel moisture content is less than 10%,.Combustion has a great influence on soil structure, soil fertility and organic matter content, after slash firing the surface soil bulk density is lower than the deep soil bulk density, soil pH value increased, the soil organic material content become lower, N content decreased, the N content of 0-5cm soil layer decreased maximum is 73.2%, the contents of available P in soil layers are increased in different degrees, the increase of available P in 0-5cm soil layer is 20.5%, the increase of 5-10cm is 30.8%, the increase of 10-15cm is 21.4%. The greater the density and moisture content of the slash, the more difficult to be ignited and sustained, the specific surface area is more easy to be ignited and the combustion speed is fast, The calorific value of the combustion decreased with the increase of the content of the ash content, and increased with the increase of the content of the extract. The environmental factors, such as oxygen concentration, ambient temperature, wind, humidity and so on, are interrelated and mutually influenced, the greater oxygen concentration, environmental humidity, wind speed, environmental pressure, the smaller air humidity, the more helpful to the combustion.
Keywords/Search Tags:Larix gmelinii, Plantation, Slash, Combustion characteristic, Influence factor
PDF Full Text Request
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