Second stage gasifier in staged gasification and integrated process

摘要

A second stage gasification unit in a staged gasification integrated process flow scheme and operating methods are disclosed to gasify a wide range of low reactivity fuels. The inclusion of second stage gasification unit operating at high temperatures closer to ash fusion temperatures in the bed provides sufficient flexibility in unit configurations, operating conditions and methods to achieve an overall carbon conversion of over 95% for low reactivity materials such as bituminous and anthracite coals, petroleum residues and coke. The second stage gasification unit includes a stationary fluidized bed gasifier operating with a sufficiently turbulent bed of predefined inert bed material with lean char carbon content. The second stage gasifier fluidized bed is operated at relatively high temperatures up to 1400° C. Steam and oxidant mixture can be injected to further increase the freeboard region operating temperature in the range of approximately from 50 to 100° C. above the bed temperature.

主权项

1. A process of conditioning a first stage syngas stream containing unwanted species in a first stage concentration formed by a first stage gasification unit of an integrated gasification process for low reactivity fuels, the process comprising:
converting the first stage syngas stream containing the unwanted species in the first stage concentration into a second stage syngas stream containing the unwanted species in a second stage concentration in a high temperature second stage turbulent fluidized bed gasifier having operating characteristics, wherein a first operating characteristic of the second stage gasifier is operating the second stage turbulent fluidized bed gasifier in the range of approximately 1100 to 1400° C., the second stage turbulent fluidized bed gasifier including bed material in a bed material region, a freeboard region above the bed material region, and an outlet for the second stage syngas stream containing the unwanted species in the second stage concentration, the second stage concentration of the unwanted species lower than the first stage concentration of the unwanted species; tempering the second stage syngas stream temperature containing the unwanted species in the second stage concentration in a syngas temperament device (STD); and returning at least a portion of bed material from the second stage turbulent fluidized bed gasifier flowing through the STD to the second stage turbulent fluidized bed gasifier; wherein the process achieves over approximately 95% carbon conversion into syngas gasifying low reactivity fuels comprising carbonaceous materials with ash content up to approximately 45 wt %.