Study Of Pyrolysis Characteristics And Comprehensive Utilization Of Organics-Containing Industrial Mixed-Salts

In this paper,basic properties and pyrolystates of organics-containing industrial mixed-salts were analyzed,including analysis of the physicochemical properties of the mixed-salt solutions,the analysis of mixed-salt organic compounds,pyrolysis gas analysis,and thermogravimetric analysis.The results show that pH value of mixed-salt solution is 6.12,which is acidic.Mixed-salt is dark red,yellowish after dissolving,and the Chroma is 32 times.The conductivity of mixed-salt solution is 9.62mS/cm.Cl^-content is 3299mg/L,accounting for 65.98%,and SO₄^2-content is 175mg/L,accounting for 3.5%,and Ca²⁺content is 72.14mg/L.The content of Mg²⁺is 70.50mg/L,and the content of calcium and magnesium is 2.86%.After mixed salt is dissolved in water,the insoluble content is 0.3%.The organic compounds in water samples mainly contain long chain alkanes,heterocyclic compounds and lipids,accounting for more than 90%,and also contain a small amount of benzene homologues,phenols,ketones and polycyclic aromatic hydrocarbons.The pyrolysis gas mainly consists of CO₂,CO,and C₁-C₃ with a calorific value of 477.37 kJ/mol.The pyrolysis experiment was conducted using fixed bed reactor.The distribution of pyrolystates was investigated at different pyrolysis conditions.Products of solid,liquid and gas were collected.The pyrolystates were analyzed by means of gas chromatography?GC?,infrared spectrum?IR?and gas chromatography-mass spectrometry?GC-MS?.Experimental results show that most of original organic matters have the carbon chains between C₇-C₃₀,while the organic matters in liquid product have the carbon chains between C₇-C₂₀.This is mainly due to thermal cracking reaction occurring during pyrolysis process.Fragmentation of side chains or branches results in the formation of small-molecule organics and conversion of macromolecules to larger molecules.The pyrolystates mainly consisted of alkanes and olefins,with a content of 45.76%.There were also a certain amount of heteroatom compounds.The nitrogen compounds are mainly aniline,pyridine,quinoline and indole and its derivatives with the content of 23.85%.The sulfur compounds are mainly thiophene and its derivatives with is the content of 7.62%.In this paper,the pyrolysis kinetics of the samples was studied using a thermogravimetric analyzer.The heating rates were 10,15,20,and 25°C/min,respectively.The experimental data were treated using F-W-O method and distributed activation energy model?DAEM?.Apparent activation energy and apparent frequency factor were obtained.The results show that linear regression coefficients of FWO and distributed activation energy model?DAEM?are higher.With increasing conversion,the activation energy is gradually increased.Based on basic experimental data,preliminary calculations of material balance and energy balance were performed for the pyrolysis process of samples.The calculated results can provide important information for selection and designing of pyrolysis equipment.The sodium chloride?NaCl?,as a product,was prepared using evaporation crystallography method for the salt solution.The quality of obtained product,as an industrial salt,met the national standard of GB/T5462-2003.