Study Of Pyrolysis Characteristics Of Livestock And Poultry Dung

The environment pollute caused by animal manure become increasingly serious as the livestock and poultry industry developing quickly.At present, the efficiency of the processing technology of poultry and animal feces is not high, and is easy to cause secondary pollution.But using the pyrolysis technology to deal with livestock and poultry dung has obvious advantages,it not only can effectively reduce the environmental burden,but also can improve the thermal efficiency. At the same time,products such as Bio-oil,solid carbon and pyrolysis gas which have the higher use value can be got.But the current domestic research on pyrolysis characteristics of livestock and poultry dung is insufficient.In this paper, the pig manure, cow muck and chicken manure were used as research object,their basic features such as industrial composition, element composition and calorific value were systematic measured and analyzed,and their pyrolysis characteristics and pyrolysis kinetics analysis were also carried out.Results are as follows.1) Pig manure, cow muck and chicken manure(dry basis) almost had the same industrial composition, the volatile content were 68.18%, 69.84% and 68.18%respectively, cow dung had the highest volatile, may pyrolyze more fully than pig manure and chicken manure. Content of each element of the three kind poultry and animal feces(dry basis) differed little, all mainly composed of C and O element, content of H, N element were low, S element’s content was the lowest, and their sum of the elements of C and H content were 48.15%, 50.14%, 43.94% respectively, of which cow dung’s was the highest, so the cow dung pyrolysis may produce more gas fuel than pig manure and chicken manure. Calorific value analysis results of the three kinds of poultry and animal feces(dry basis) showed that the calorific value of the pig and the cow dung were similar,their high calorific value were 16.93 KJ/g and 16.86 KJ/g respectively, and low calorific value were 15.35 KJ/g and 15.34 KJ/g respectively, higher than chicken manure’s, it meant that pig and cow dung’s pyrolysis temperature may be lower than chicken manure’s.2) Analysis of pyrolysis TG and DTG curve showed that, of the three kinds of livestock and poultry dung, Pig and cow dung volatile released ease, easily than chicken manure, the maximum pyrolysis rate of cow dung is highest, the final residual solid of cow dungis the least. The generation of pyrolysis products increased as the temperature increasing, and in 200~400℃ the generation rate of pyrolysis products reached the fastest,samples pyrolyzed most acutely. With the increase of heating rate, the initial degradationtemperature, the maximum pyrolysis rate and the corresponding temperature of cow dung all increased, and volatile separated out more easily, but solid residue at the end increased.3) Three methods were used for livestock and poultry dung’s pyrolysis dynamics analysis. Pyrolysis kinetic parameters of the cow dung pyrolysis were obtained through the method of FWO pyrolysis, and it was found that activation energy of pyrolysis of the cow dung reduced along with the increasing of conversion rate, and the activation energy was the lowest when conversion rate was 60%,which was 157.86 KJ/mol, and the average pyrolysis activation energy under different conversion rate was 170.60 KJ/mol. The dynamic model of three kinds of livestock and poultry dung were determine to be D6three-dimensional diffusion model through the Coats-Redfern integral method, its mechanism of function is f(α)=3/2(1-α)4/3[(1-α)-1/3-1]-1, and the calculated results showed that,the activation energy of pig was 87.8 KJ/mol, frequency factor was3.5×106min-1;The activation energy of cow dung in the heating rate of 10℃/min,20℃/min, 30℃/min, were 101.5 KJ/mol, 101.0 KJ/mol, and 102.5 KJ/mol,respectively,corresponding frequency factors were 4.3×107min-1,2.6×107min-1,3.9×107min-1; The activation energy of chicken manure was 68.2 KJ/mol, frequency factor was3.3×104min-1. The pyrolysis activation energy of cow dung got by cow dung was 132.63KJ/mol, frequency factor was 1.58 ×1011min-1. Then the three methods were compared with each other,and showed that the value of the activation energy got by FWO method was the highest, and its experiment error was the least. It concluded that FWO method had the best result on pyrolysis kinetics analysis of livestock and poultry dung.