Method for removing and suppressing coke formation during pyrolysis

A method for injecting a liquid solution into a hot gaseous process stream in a thermal cracking furnace tube, comprising the steps of:

• providing a first tube, a second tube which concentrically surrounds said first tube thereby providing a first insulating annular space between the first and second tubes, and a third tube which concentrically surrounds said second tube thus providing an annular channel, and a centrifugal atomizing nozzle with an inlet and an outlet, a tubular gaseous process stream deflecting, mixing and vaporizing device having an inlet and an outlet at respective axial ends and process gas admitting apertures between the ends;
• wherein the inlet of the deflecting, mixing and vaporizing device is in coaxial registration with the nozzle outlet;
• wherein one end of said first tube is connected to a pressure supply of liquid solution and another end of said first tube is mounted coaxially to the inlet of the nozzle so that the nozzle and deflecting, mixing and vaporizing device are concentrically surrounded by the third tube;
• wherein the outlet end of the deflecting, mixing and vaporizing device extends across substantially an entire diameter of the annular channel, wherein one end of said third tube is connected to a process gas supply means and the other end of said third tube leads to a metal-walled reactor for thermally cracking a hydrocarbon gas;
• passing a pressurized continuous stream of liquid solution through said first tube, and passing a heated hydrocarbon process gas feed stream through said third tube;
• adjusting the flow rates of the streams flowing through the first and the third tubes so that the nozzle atomizes the liquid solution during injection, spraying small drops into the inlet end of the deflecting, mixing and vaporizing device, dispersing the drops within the gaseous process stream passed through the apertures thereby vaporizing the drops entirely within the deflecting, mixing and vaporizing device without the liquid solution contacting the deflecting, mixing and vaporizing device and the third tube.