Process for production of carbon black
Off-gas from a carbon black furnace is employed as a combustion gas feed stream to the burner or combustion zone of the same or a different carbon black furnace in accordance with certain embodiments, suitable conduit and valving is provided to pass off-gas, from which carbon black has been substantially removed, from any and all of multiple different carbon black furnaces to the burner. The off-gas is heated, preferably by plasma heating, and dewatered. Carbon dioxide stripping or rather stripping of gas components from the dewatered heated off-gas is found to be unnecessary to achieve economically favorable use of off-gas recirculation.
1. A furnace carbon black producing process comprising the steps of:
(a) obtaining off-gas from a carbon black furnace,
(b) dewatering and heating the off-gas and substantially removing any existing carbon black therefrom to obtain dewatered and heated off-gas, and then
(c) feeding a combustion gas feed stream comprising the dewatered and heated off-gas and feeding an oxidant gas stream comprising an oxidant gas to a burner portion of a carbon black furnace, wherein the carbon black furnace to which the combustion gas feed stream and oxidant gas feed stream are fed is a different carbon black furnace from the carbon black furnace of step (a), wherein the carbon black furnace to which the combustion gas feed stream and oxidant gas feed stream are fed comprises said burner portion wherein a combustion gas feed stream is combusted in the presence of an oxidant gas feed stream to produce hot combustion gases and a reactor portion downstream of said burner portion wherein the hot combustion gases interact with a hydrocarbon feedstock to produce carbon black,
(d) controlling the combustion gas feed stream and oxidant gas feed stream so that combustion of the combustion gas feed in the burner portion to produce hot combustion gases takes place in a fuel-rich condition so that the combustion gas feed stream does not completely combust in the burner portion, and
(e) producing carbon black in the reactor portion of the carbon black furnace by interaction of the hot combustion gases with a hydrocarbon feedstock under said fuel rich conditions,
wherein in carrying out step (e), a hydrocarbon feedstock is supplied to the reactor portion by feeding the hydrocarbon feedstock to a passage between the burner portion and the reactor portion of the carbon black furnace.
2. The furnace carbon black producing process in accordance with claim 1 , wherein in steps (c)-(e), the heated, dewatered off-gas from step (b) is the only combustible gas supplied to the burner portion and wherein the combustible gas feed stream and oxidant gas feed stream are controlled to provide deep rich fuel conditions in steps (d) and (e).
3. The furnace carbon black producing process in accordance with claim 1 , wherein the heated, dewatered off-gas is dewatered by means of pressure swing absorption.
4. The furnace carbon black producing process in accordance with claim 1 , wherein the off-gas is subjected to plasma heating subsequent to removal of carbon black therefrom and prior to being fed to the burner portion.
5. The furnace carbon black producing process in accordance with claim 1 , wherein the oxidant gas feed stream is subjected to plasma heating prior to being fed to the burner portion.
6. The furnace carbon black producing process of claim 1 , wherein hydrocarbon feedstock is subjected to plasma heating prior to being fed to the carbon black furnace.
7. The furnace carbon black producing process of claim 1 , wherein combustion gases produced in the burner portion by combustion of the heated, dewatered, off-gas with the oxidant gas feed stream are subjected to plasma heating prior to contacting hydrocarbon feedstock in the reactor portion of the carbon black furnace.
8. The furnace carbon black producing process of claim 1 , wherein the oxidant gas feed stream to the burner portion comprises air plus oxygen enhancement, wherein the oxygen enhancement is produced by a pressure swing adsorption process.
9. The process of claim 1 , wherein steps (a) through (e) are repeated and wherein step (e) of producing carbon black provides the off-gas for the succeeding step (a).