(114d) Economical Desulfurization of Petroleum Coke

CO Generator and Process for Desulfurizing Solid Carbon-based Fuels; Author and owner of the Patent is Louis Herrington, Owner of LEHCO, a Chemical Engineering Consultancy.

ABSTRACT

A process is presented whereby hot Carbon Monoxide (CO) gas is generated under pressure in an external Combustor by the partial oxidation of a carbon-based solid fuel. This pressurized, hot CO gas or CO gas mixture is then transferred to a desulfurizing vessel containing a second carbon-based solid fuel. The hot CO laden gas and solid material contact in a counter-flow arrangement where the CO reacts with and removes sulfur impurities from the second carbon fuel. The temperature of the pressurized CO laden gas from the Combustor is controlled by varying the oxidizer feed gas composition. The Combustor also contains a means for desulfurizing its feed fuel by flowing a portion of the hot CO gas generated up through the inlet solid fuel feed line. The desulfurizer vessel is comprised of three stages, a preheat stage, a desulfurizing stage, and a cooling stage. Hot CO gas from the Combustor enters the desulfurizer section where it mixes with a recycle gas stream coming up from the cooling stage below. The gas exiting the desulfurizer section is split into an exhaust stream and a recycle stream. The recycle stream travels up through the preheat section and heats the incoming material being treated. The cooled recycle gas exits the top of the system and flows to a recycle blower. The recycle gas is scrubbed of impurities by activated carbon prior to being re-injected into the bottom of the cooling section. The hot exhaust stream from the desulfurizer section is first quenched by mixing with a small water spray and a second exhaust gas recycle stream. The cooled exhaust gases are passed over a catalyst that converts carbonyl sulfide (COS) and carbon disulfide (CS2) gases to hydrogen sulfide (H2S) that is removed from the system by conventional processes. The Combustor/Desulfurizer process is useful for producing high-value low-sulfur petroleum coke by generating the required heat from a low-value coke, such as shot coke. In an alternate embodiment, the combustor is used to calcine and desulfurize coal or other solid carbon fuel in a batch process. The Combustor can also be used independently to supply hot reducing gas for any application.