Study On Pyrolysis Technology Of Deinking Sludge

In this paper, the factors of deinking sludge pyrolysis were investigated. Scanning Electron Microscope was used to observe the appearance of the deinking sludge, Fourier Transform Infrared Spectrometer was used to analyze the molecular structure of deinking sludge, and the metal elements were detected by Inductively Coupled Plasma Atomic Emission Spectrometry. Then the primary property of the deinking sludge was got. The pyrolysis characteristics of deinking sludge was researched by thermo-gravimetric analysis, and the curves of TG and DTG were simulated to establish the dynamical model. TG-FTIR analysis was introduced to study the pyrolysis characteristics of un-catalyzed and catalyzed deinking sludge. The pyrolysis of deinking sludge was conducted in the tubular furnace to research pyrolysis products distribution of deinking sludge by using Gas Chromatography, Elemental Analyzer, Mass Select-detector (GC-MS) and FTIR.The experimental results of the research of primary property of deinking sludge showed that, there were large amounts of organics which were mainly fiber fines and ink, and lots of inorganic substances which mainly contained large portion of calcium carbonate and kaolin in deinking sludge. In the deinking sludge, content of Ca element was the maximum, followed by Al element, but the contents of heavy metal elements were the minimum. The contents of most metal elements of deinking sludge during incineration were decreased while the temperature increased.The pyrolysis characteristics and kinetic of deinking sludge were got by means of TGA. TGA studies showed that the pyrolysis reaction of deinking sludge consist of three stages, water lose stage, the main pyrolysis stage and decomposition of residual carbon and inorganic filler stage. The dynamical model of deinking sludge pyrolysis process could be expressed by three first-order parallel reaction. TG and DTG curves of deinking sludge pyrolysis showed that TG and DTG curve have the same diversification at different heating rates. With the increase of heating rate, these curves moved to higher temperature, and the residual solid yield increased. Besides in the low temperature region and high temperature region of the pyrolysis, the activation energy and pre-exponential factor increased with the increase of heating rate.In the catalytic pyrolysis process of deinking sludge, catalysts (MgCl2、NaCl、 and CaCl2) reduced the initial temperature and the temperature of maximum mass loss rate. In addition, in main reaction zone the activation energy of the reaction became smaller than that of un-catalyzed deinking sludge. TG-FTIR analysis was used to examine the products from the pyrolysis of un-catalyzed and catalyzed deinking sludge. The experimental results of catalytic pyrolysis showed that the pyrolysis temperature of deinking sludge was lower because of MgCl2, in addition, CO, CO2 and saturated C-H substances were found in lower pyrolysis temperature. However, the addition of NaCl had little effects on products which were got in the deinking sludge pyrolysis.The pyrolysis of deinking sludge was conducted in the tubular furnace at 500-800℃ to research pyrolysis products distribution. The results showed that the solid yield was the highest in the three phase products, but the gas yield was the lowest. With pyrolysis temperature increasing, solid production rate decreased but the gas yield increased while liquid yield changed hardly. The gas products included CO2, CO, CH4, H2, C2H4, etc. The liquid products were mainly consisted of benzene derivatives, PAHs, indene, naphthalene derivatives, a little alkenes and alkanes. The content of Styrene was the highest in the liquid products. The solid products mainly composed of calcium carbonate, kaolin, metakaolin and calcium oxide.