Studies in a moving bed pressure gasifier: prediction of reaction zones and temperature profile

Sequential layer samples were collected from a moving bed pressure gasification pilot plant operating at 2.0 MPa after it was quenched by cutting off the supply of oxygen and steam, and the samples were then analyzed. The studies were made with two low-rank coals. Based on the proximate and ultimate analyses and Gray-King assay, three zones - fast devolatilization, slow devolatilization with gasification, and gasification - could be indicated in the gasifier. From a correlation obtained earlier between volatile matter content in the char and the temperature of low-temperature carbonization in a Lurgi Spuelgas type of reactor, the temperature profile in the gasifier was predicted using the volatile matter content in the sequential layer samples. About two-thirds of the total fuel bed height of 3500 mm was for fast and slow devolatilizations and the rest for gasification.