Process for Cracking of Waste Oil by Microwave

Abstract

A process and apparatus for heating liquid material, which are particularly suitable for refining waste oil, are disclosed. The process comprises the steps of creating a swirling body of liquid material, such as waste oil, within a reaction chamber, and exposing the swirling body of material to microwave radiation.

1 . A process for refining waste oil, the process comprising transferring waste oil from a reservoir tank into a reaction chamber such that a swirling body of waste oil is formed within the reaction chamber, and exposing the swirling body of waste oil to microwave radiation such that cracking reactions occur, wherein waste oil that cools within the reaction chamber before undergoing any cracking is replaced from below by swirling bodies of waste oil at a higher temperature, and the cooler waste oil falls, under the action of gravity, along a circuit conduit into the reservoir tank. 
     
     
         2 . A process as claimed in  claim 1 , wherein waste oil is transferred by one or more injection conduits from a reservoir tank either directly into the reaction chamber, or into the circuit conduit that communicates with the reaction chamber, such that a swirling body of waste oil is formed within the reaction chamber. 
     
     
         3 . A process as claimed in  claim 2 , wherein a swirling body of waste oil is formed within the circuit conduit, which communicates with an opening in a lower part of the reaction chamber, and this swirling body rises by thermal effects into the reaction chamber. 
     
     
         4 . A process as claimed in  claim 3 , wherein the waste oil is guided by the one or more injection conduits into a portion of the circuit conduit that is offset from its central, longitudinal axis, along a direction that is orientated transversely to that axis. 
     
     
         5 . A process as claimed in  claim 1 , wherein as the cracking reactions refine the waste oil and the products are removed, the waste oil is replenished within the reservoir tank so as to maintain the level of waste oil within the reservoir tank substantially constant. 
     
     
         6 . A process as claimed in  claim 1 , wherein the waste oil is heated before being introduced into the reservoir tank, and is heated further within the reservoir tank. 
     
     
         7 . A process as claimed in  claim 1 , wherein a microwave radiation sensitiser is added to the waste oil before it is transferred to the reaction chamber. 
     
     
         8 . A process as claimed in  claim 7 , wherein the sensitiser is added to the waste oil before it is introduced into the reservoir tank. 
     
     
         9 . A process as claimed in  claim 8 , wherein other additives are also added to the waste oil before it is introduced into the reservoir tank. 
     
     
         10 . A process as claimed in  claim 1 , wherein the circuit conduit extends from an opening in the lower part of the reaction chamber to a port in a lower portion of the reservoir tank. 
     
     
         11 . A process as claimed in  claim 1 , wherein solid sediments and other heavy materials build up in a lower portion of the reservoir tank, and this heavy material is intermittently drained through an outlet port in the base of the reservoir tank. 
     
     
         12 . A process as claimed in  claim 1 , wherein a catalytic substrate is situated within the reaction chamber during exposure of the swirling body of material to microwave radiation. 
     
     
         13 . A process as claimed in  claim 1 , wherein the reaction chamber is housed within an electrically-conductive jacket, with an inert gas-filled space separating the reaction chamber from the wall of the jacket, and microwave radiation enters the jacket through a window, before entering the reaction chamber to be absorbed by the swirling body of waste oil. 
     
     
         14 . A process as claimed in  claim 13 , wherein the entire reaction chamber is exposed to microwave radiation. 
     
     
         15 . A process as claimed in  claim 13 , wherein a waveguide transmits the microwave radiation from a source to the window of the jacket. 
     
     
         16 . A process as claimed in  claim 1 , wherein vapour products, and also any entrained liquid droplets and solid particles, escape from the reaction chamber through an upper opening of the reaction chamber. 
     
     
         17 . A process as claimed in  claim 16 , wherein the vapour products, and any entrained liquid droplets and solid particles, passing through the upper opening of the reaction chamber are transferred to an upper portion of the reservoir tank where the entrained liquid droplets and solid particles are returned to the waste oil. 
     
     
         18 . A process as claimed in  claim 17 , wherein the vapour products flow into a product recovery apparatus through an upper outlet port of the reservoir tank. 
     
     
         19 . An apparatus for refining waste oil, the apparatus comprising a reservoir tank, at least one injection conduit configured to transfer the waste oil from the reservoir tank into the reaction chamber such that a swirling body of waste oil is formed within the reaction chamber, in use, and a source of microwave radiation adapted to expose the swirling body of waste oil to microwave radiation such that cracking reactions occur, wherein the apparatus is adapted such that waste oil that cools, in use, within the reaction chamber before undergoing any cracking is replaced from below by swirling bodies of waste oil at a higher temperature and the cooler waste oil falls, under the action of gravity, along a circuit conduit into the reservoir tank. 
     
     
         20 . An apparatus as claimed in  claim 19 , wherein the swirling body of waste oil is created within the reaction chamber by the one or more injection conduits that transfer waste oil from a reservoir tank either directly into the reaction chamber, or into the circuit conduit that communicates with the reaction chamber, such that a swirling body of waste oil is formed within the reaction chamber. 
     
     
         21 . An apparatus as claimed in  claim 20 , wherein the one or more injection conduits are adapted to guide the waste oil into a portion of the circuit conduit that is offset from its central, longitudinal axis, along a direction that is orientated transversely to that axis. 
     
     
         22 . An apparatus as claimed in  claim 20 , wherein the reaction chamber is cylindrical, with open upper and lower ends, and is orientated generally vertically. 
     
     
         23 . An apparatus as claimed in  claim 22 , wherein the portion of the circuit conduit that is immediately below the reaction chamber is orientated vertically, and the injection conduits are adapted to feed the waste oil into the circuit conduit in a generally horizontal direction. 
     
     
         24 . An apparatus as claimed in  claim 23 , wherein the open lower end of the reaction chamber is in sealed communication with the circuit conduit, and has an internal diameter that matches the internal diameter of the circuit conduit. 
     
     
         25 . An apparatus as claimed in  claim 19 , wherein the entire wall of the reaction chamber is formed from a heat-resistant glass. 
     
     
         26 . An apparatus as claimed in  claim 19 , wherein the circuit conduit extends from an opening in the lower part of the reaction chamber to a port in a lower portion of a reservoir tank. 
     
     
         27 . An apparatus as claimed in  claim 19 , wherein a catalytic substrate is situated within the reaction chamber. 
     
     
         28 . An apparatus as claimed in  claim 27 , wherein the catalytic substrate comprises carbon as a catalyst. 
     
     
         29 . An apparatus as claimed in  claim 28 , wherein the catalytic substrate has the form of a rod that extends along a central axis of the reaction chamber. 
     
     
         30 . An apparatus as claimed in  claim 27 , wherein the catalytic substrate is mounted at its ends, with the mountings being situated within inlet and outlet ports for the reaction chamber. 
     
     
         31 . An apparatus as claimed in  claim 30 , wherein each of the mountings comprises a central hub for receiving an end portion of the catalytic substrate, and a plurality of radial support struts. 
     
     
         32 . An apparatus as claimed in  claim 31 , wherein the radial support struts in the inlet port have the form of deflector blades, the deflector blades being adapted to deflect waste oil flowing into the reaction chamber transversely relative to the longitudinal axis of the reaction chamber so as to facilitate formation of a swirling body of waste oil. 
     
     
         33 . An apparatus as claimed in  claim 19 , wherein a microwave barrier is disposed within an outlet port for the reaction chamber, and the microwave barrier comprises one or more electrically conductive members configured to prevent escape of microwave radiation from the reaction chamber through the outlet port. 
     
     
         34 . An apparatus as claimed in  claim 33 , wherein the microwave barrier has the form of a turbine rotor that is adapted to be rotated by material exiting the reaction chamber through the outlet port. 
     
     
         35 . An apparatus as claimed in  claim 34 , wherein the apparatus includes means for monitoring the rotation of the turbine rotor, and means for calculating therefrom the rate of flow through the outlet port. 
     
     
         36 . An apparatus as claimed in  claim 19 , wherein the reaction chamber is housed within an electrically-conductive jacket. 
     
     
         37 . An apparatus as claimed in  claim 36 , wherein the reaction chamber is mounted co-axially within a cylindrical jacket, with an inert gas-filled space separating the reaction chamber from the wall of the jacket. 
     
     
         38 . An apparatus as claimed in  claim 37 , wherein the jacket includes a window through which microwave radiation is able to enter the jacket, before entering the reaction chamber to be absorbed by the swirling body of waste oil. 
     
     
         39 . An apparatus as claimed in  claim 38 , wherein the window is dimensioned and configured such that the entire reaction chamber is exposed to microwave radiation. 
     
     
         40 . An apparatus as claimed in  claim 38 , wherein the apparatus includes a waveguide that transmits the microwave radiation from a source to the window of the jacket. 
     
     
         41 . An apparatus as claimed in  claim 19 , wherein the apparatus includes means for separating the products of the cracking reactions. 
     
     
         42 . An apparatus as claimed in  claim 41 , wherein the reaction chamber has an upper opening through which vapour products, and also any entrained liquid droplets and solid particles, are able to escape from the reaction chamber. 
     
     
         43 . An apparatus as claimed in  claim 42 , wherein the apparatus is adapted such that the vapour products, and any entrained liquid droplets and solid particles, passing through the upper opening of the reaction chamber are transferred to an upper portion of the reservoir tank where the entrained liquid droplets and solid particles are returned to the waste oil. 
     
     
         44 . An apparatus as claimed in  claim 43 , wherein the reservoir tank includes an upper outlet port through which the vapour products are able to flow into a product recovery apparatus.