Patent ID: 6941879
Filing Date: 2005-09-13
Classification: C10B,C10J,C10K,F02C,Y02E,Y02T

Abstract:
1. A process for the generation of a fuel gas by dry distillation of carbonaceous solids in a dry distillation zone into which the carbonaceous solids are fed via a solids supply and in which the solids are heated, where applicable dried and are dry-distilled with the liberation of dry distillation volatiles and, by further conversion of those volatiles in a gasification zone in the presence of carbonaceous solids passing through the gasification zone at least in part under gravity in the form of a bed of particulate solids, to which gasification media are fed in substoichiometric quantities, the dry distillation volatiles withdrawn from the dry distillation zone entering the gasification zone and flowing through the bed of particulate solids being there maintained in co-current with the direction of travel of the latter, an embers bed being formed by the bed of particulate solids in the terminal portion of the gasification zone in the region of a fire grate element acting further as a solids discharge element for the residual solids after completion of the gasification, through which embers bed the gas formed in the bed of particulate solids passes, whereby condensable volatiles components contained in the gas are cracked, and wherein the fuel gas so generated is withdrawn from the lower region of the bed of particulate solids of the gasification zone, wherein gas containing oxygen is introduced into the dry distillation zone in substoichiometric amount for generating heat by partial combustion of the solids to be dry-distilled passing through the dry distillation zone in the form of a bed of particulate solids under the action of gravity before the generated fuel gas product is separated from ashes and any cinders and is withdrawn and forwarded for further use, said process further comprising additional measures for further decreasing the content of condensable dry distillation volatiles in the fuel gas product by increasing the intimate contact of the gases and vapours with the solids beds through which they pass, selected from either or both of the following: A) that the embers bed of the gasification zone is conducted from the higher lying regions of said zone under gravity towards and through a constricted lower peripheral passage region of the gasification zone defined between the outer periphery of the fire grate element and the inner periphery of exterior walls of a reactor in which the process is performed, and in co-current therewith the dry distillation volatiles and gasification gases and any gaseous cracking products are passed in intimate contact with and through the embers bed and from there travels down a funnel-shaped inwardly sloping constricting pathway below the fire grate element leading into and ending with the ash withdrawal region, where the separation occurs between the ashes and any cinders and the generated fuel gas product; B) that in at least one dry distillation zone in the form of a bed of particulate solids under the action of gravity the gas present in that zone passes through the solids in counter-current to the direction of travel of the solids to be dry distilled, the solids thereby being dry distilled and the dry distillation volatiles thereby formed in the dry distillation zone being withdrawn from the dry distillation zone near the solids supply region and that at least part of the dry distillation volatiles formed in the dry distillation zone withdrawn from near the solids supply region feeding the dry distillation zone with carbonaceous solids are from there forwarded into the gasification zone, where they, together with gasification gases and any gaseous cracking products, pass in co-current with and in intimate contact with and through the embers bed of the gasification zone and are subjected to cracking of condensable volatiles, before being separated from ashes and any cinders and being withdrawn as a fuel gas product, subject further to the condition that, at least when feature A) is absent and where the at least one dry distillation zone, wherein the bed of particulate solids and the gas present therein pass in counter-current to one another, is maintained in a first vessel, distinct and separate from a second vessel, wherein the bed of carbonaceous solids and the gases and vapours pass in co-current with one another,