An Improved Comprehensive Model of Pyrolysis of Large Coal Particles to Predict Temperature Variation and Volatile Component Yields

Wenning Zhou,Xunliang Liu,Hailong Huo,Qinye Li,Ruifeng Dou

doi:10.3390/en12050884

Abstract

In this work, an improved comprehensive model was developed for large coal particles to predict temperature variation and volatile component yields. The kinetics model of volatile component yields, where the volatile matters were assumed to comprise nine species, was combined with heat transfer model. The interaction between volatile yield and heat transfer during pyrolysis of large Maltby coal particles was investigated. An apparent temperature difference has been observed between the surface and core of particles at the initial heating stage. The non-uniform temperature distribution inside coal particles causes non-simultaneous volatile yields release from the surface and core area. The volatile release occurs after the coal temperature rises higher than 350 °C, and its yield steeply increases within the temperature range of 450–520 °C. The peak of volatile release rate corresponds to about 485 °C due to the rapid release of tar and H2O. The tar is almost completely released at around 550 °C. With the increasing particle size, the difference in temperature and volatile yield between the surface and core increases at the end of heating. The results are expected to provide insights into the interaction between heat transfer and volatile yields during pyrolysis of large coal particles.

Highlights

Coal, one of the primary fossil fuel sources, plays an important role in China, owing to the abundant reserves and its competitively low price compared to natural gas and oil [1]
The need for reduced greenhouse gas emissions has spurred the development of clean coal technology, such as chemical looping combustion (CLC) [8], integrated gasification combined cycle (IGCC) [9], multi-stage coal gasification (MSCG) [10], and so on
We have developed a comprehensive model for coal pyrolysis coupled with heat transfer inside the particle, considering the heat effect of pyrolysis reaction and convective heat transfer due to volatile matters release [39,40]

Summary

Introduction

One of the primary fossil fuel sources, plays an important role in China, owing to the abundant reserves and its competitively low price compared to natural gas and oil [1]. The need for reduced greenhouse gas emissions has spurred the development of clean coal technology, such as chemical looping combustion (CLC) [8], integrated gasification combined cycle (IGCC) [9], multi-stage coal gasification (MSCG) [10], and so on. These innovative technologies based on the pyrolysis and gasification of coal have been applied in the manufacturing industry. Pyrolysis, or devolatilization, as the primary process during coal gasification and combustion, plays a key role in determining the gaseous production and carbon structure, which causes an inevitable effect on subsequent processes [11,12]. Li et al [13]

Objectives

Results

Conclusion