It is known that caking coal is difficult to be gasified in fluidized bed (FB) because of coal particle agglomeration in the dense bottom of the bed. Previous literature studies have shown that pre-oxidizing the caking coal can prevent its caking propensity and disperse coal particles. To solve the problem, researchers from Institute of Process Engineering, Chinese Academy of Sciences devised jetting pre-oxidation fluidized bed gasification (JPFBG) technology to gasify caking coal in FB.

In JPFBG technology, O₂-containing gas was used to feed the coal particles. A 150kg/h pilot plant was set and the caking coal was successfully gasified. It is critical to keep an optimal proportion of O₂ during the jet feeding. The results show that jetting can pre-oxidize and disperse the coal to suppress its caking propensity.

Laboratory jetting pre-oxidation test was performed before the pilot plant. Bench-scale experiments were designed to validate the caking destruction via jetting pre-oxidation for caking coals. In the pilot test of JPFBG, 150kg/h pilot-scale system was built.

The tests in the laboratory and pilot JPFBG plant clarified following conclusions. The better caking destruction effect by the jetting pre-oxidation was at the higher O₂ concentration in the jetting gas and the higher pre-oxidation temperature. Under the test of JPFBG pilot plant conditions, no particle caking or agglomeration was observed in the gasifier. It is important to set the O₂ content applied to the jet feeding.

This study provided an effective technology for caking coal gasification in fluidized bed. Researcher say that further studies including coal size, jetting gas velocity and jetting location will be performed.

More details see: http://www.sciencedirect.com/science/article/pii/S030626191300353X