Experimental study of laser pyrolysis of coal and residual oil

•Established a lab-scale laser pyrolysis system for pyrolysis study at ultra-high temperature and fast heating rate.•Measured ultra-high temperature in milliseconds through a two-color infrared thermometer.•Revealed the laser pyrolysis performance of coal and oil residues at various conditions.•Discussed correlations and differences between laser and plasma pyrolysis processes. A lab-scale laser pyrolysis platform was set up to study the pyrolysis of coal and residual oil to light gases combining high accuracy, good repeatability and ultra-high temperature, fast heating rate. With a high-power CW CO2 laser used as heat source, the laser pyrolysis took place as a procedure-controlled reaction process connected with a specially designed GC to analyze the gas products on line. The temperature of samples was measured by a two-color infrared pyrometer in milliseconds time-step, and the measured ultimate temperature and heating rate exceeded 2900 K and 3 × 104 K/s respectively. Through a series of experiments, the accuracy and reliability of the laser pyrolysis platform are verified and the effects of sample weight, environmental atmosphere, laser irradiation time and power, hydrogen content in atmosphere on the yields of gas products were investigated. The appropriate operating conditions are: the weight of residual oil less than 1.0 mg, the laser irradiation time longer than 3.0 s, laser irradiation power stronger than 90 W. The relationship between laser pyrolysis and plasma pyrolysis processes has also been discussed in this work. This work established an efficient, easy-to-use method for the preliminary feedstock selection of plasma pyrolysis process because C1 + C2 yield from laser pyrolysis could be used as a criterion for plasma pyrolysis.