A chemical reactor including reformer tubes for reforming a first feed stream including a hydrocarbon gas and steam. The chemical reactor includes one or more reformer tubes arranged to being heated by an electrically driven heat source. The reformer tube includes a first inlet for feeding said first feed stream into a first reforming reaction zone of the reformer tube, and a feed conduit arranged to allow a second feed stream into a second reforming reaction zone of the reformer tube. The second reforming reaction zone is positioned downstream of the first reforming reaction zone. The feed conduit is configured so that the second feed stream is only in contact with catalyst material in the second reforming reaction zone. A process of producing CO rich synthesis gas at low S/C conditions.