Abstract:
A reactor and a reactor system for carrying out high temperature and high pressure reactions is disclosed herein. The reactor has an isolatable inner vessel for allowing for heat energy efficient cooling and heating of the reactor. The reactor comprises an outer reactor adapted for withstanding a reaction pressure and a reaction temperature, the outer reactor having a sealable reactor lid; an inner vessel within the outer reactor for containing a reaction solution and at least one reaction vessel, the inner vessel being open to the outer reactor such that the reaction pressure of the inner vessel and the outer reactor are substantially equalized and vapour in the inner vessel passes to the outer vessel, the inner vessel having a splatter shield for substantially preventing spillage of the reaction solution from the inner vessel into the outer reactor; a vapour injector in communication with the inner vessel for injecting vapour into the inner vessel for heating the reaction solution; an outlet in the outer vessel for exhausting vapour from the outer reactor and the inner vessel; and an outer reactor outlet for draining a liquid contained between the outer reactor and the inner vessel.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to reactors and reactor systems for high temperature and high pressure reactions. 
       TECHNICAL BACKGROUND 
       [0002]    High temperature and high pressure reactions require a reactor adapted to handle such conditions. Reactions, such as the devulcanization of rubber or mineral extraction, are examples of high temperature high pressure reactions. Rubber can be devulcanized by heating it to between 250° C. and 350° C. in an aqueous solution for about one hour with pressures up to about 1500 psi as described in Canadian patent application 2,441,713 which is incorporated herein. The rubber pieces are usually relatively large as smaller pieces tend to agglomerate and become sticky when processed. Because of this, a batch type of reactor is required. The reactor required to contain the high temperatures and pressures involved is very heavy and has a very large thermal mass and therefore requires a substantial amount of heat energy to raise the temperature of the reactor up to a reaction temperature. Current reactors and reactor systems require many hours of heating to heat a reactor full of liquid up to temperature and then cool it down and are therefore not very commercially practical. Additionally, reheating of a reactor after cool-down requires a large amount of heat energy as the outer reactor wall of a high pressure reactor has a very large thermal mass. 
         [0003]    Furthermore, heating a large reactor from the outside that is full of liquid and a material to be processed, such as rubber or in a mineral extraction from rocks or the like (that is a poor thermal conductor), also results in large temperature gradients within the reactor. 
         [0004]    Additionally, much of the heat energy required to increase the temperature of the reactor or reactants and/or solvent to a processing temperature is lost when the reaction is complete and the reactor is cooled for removal of the reaction product. 
         [0005]    There is therefore a need for a reactor whereby the reactant can be rapidly and evenly heated to the processing temperature, held there for a desired time period and then rapidly cooled. 
       SUMMARY OF INVENTION 
       [0006]    The present invention relates to a reactor and a reactor system for processing a high temperature, high pressure reaction. Reactors of the present invention have an isolatable inner vessel allowing for efficient heating and cooling of a reaction to be carried out therein. The inner vessel is for containing a reaction solution and a reaction vessel. The inner vessel may be isolated from an outer reactor through which heat may be constantly applied. A separate vapour injector for providing additional heating energy via vapour directly to the inner vessel is used to bring the temperature of the reaction solution up to a reaction temperature. During a cool-down phase of the reaction, any liquid between the inner vessel and the outer reactor is removed thereby isolating the inner vessel from the outer reactor. Vapour inside the reactor is then exhausted. Lowering of the reactor pressure causes the liquid inside the inner reactor to evaporate. The evaporation of the liquid causes cooling and the liquid in the inner vessel is cooled by the process of exhausting the vapour from the reactor. Upon pressure equalization with the outside atmosphere the reactor will be at a suitable temperature and may be opened and the reaction vessels removed. In this way cool-down of the reaction product can be done quickly and re-heating of the reactor does not require substantial re-heating of the outer reactor. In the reaction system, exhausted vapour may be reused to heat a reaction solution of an additional reactor thereby recovering a portion of the heat energy. 
         [0007]    One aspect of the present invention provides for a reactor comprising: 
         [0008]    an outer reactor adapted for withstanding a reaction pressure and a reaction temperature, the outer reactor having a sealable reactor lid; 
         [0009]    an inner vessel within the outer reactor for containing a reaction solution and at least one reaction vessel, the inner vessel being open to the outer reactor such that the reaction pressure of the inner vessel and the outer reactor are substantially equalized and vapour in the inner vessel passes to the outer vessel, the inner vessel having a splatter shield for substantially preventing spillage of the reaction solution from the inner vessel into the outer reactor; 
         [0010]    a vapour injector in communication with the inner vessel for injecting vapour into the inner vessel for heating the reaction solution; 
         [0011]    an outlet in the outer vessel for exhausting vapour from the outer reactor and the inner vessel; and 
         [0012]    a reaction solution outlet for draining the reaction solution from the inner vessel. 
         [0013]    Another aspect of the present invention provides for a reactor system for transferring heat energy from at least a first reactor to a second reactor, the reactor system comprising: 
         [0014]    the first and second reactors comprising: 
         [0015]    an outer reactor adapted for withstanding a reaction pressure and a reaction temperature, the outer reactor having a sealable reactor lid; 
         [0016]    an inner vessel within the outer reactor for containing a reaction solution and at least one reaction vessel, the inner vessel being open to the outer reactor such that the reaction pressure of the inner vessel and the outer reactor are substantially equalized and vapour in the inner vessel passes to the outer vessel, the inner vessel having a splatter shield for substantially preventing spillage of the reaction solution from the inner vessel into the outer reactor; 
         [0017]    a vapour injector in communication with the inner vessel for injecting vapour into the inner vessel for heating the reaction solution; 
         [0018]    a reaction solution outlet for draining the reaction solution from the inner vessel; and 
         [0019]    an outlet in the outer vessel for exhausting vapour from the outer reactor and the inner vessel; 
         [0020]    a manifold in communication with the outlet of each reactor and the vapour injector of each reactor for transferring vapour from the first reactor to the second reactor to heat the reaction solution. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is an illustrative schematic diagram of a batch reactor according to one embodiment of the present invention; 
           [0022]      FIG. 2  is an illustrative schematic diagram of a multiple reactor system according to one embodiment of the present invention having an energy recovery system; and 
           [0023]      FIG. 3  is a flow chart illustrating a method of providing energy recovery in a multiple reactor system according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Reactors of the present invention are known as batch type reactors and are used for processing high temperature and high pressure reactions such as the devulcanization of rubber or mineral separation from rocks or the like. However, reactors of the present invention may also be used for processing lower temperature and/or lower pressure reactions. 
         [0025]    Reactors of the present invention allow for quicker cool-down of reaction product by isolating the reaction product in a reaction vessel held in an inner vessel of the reactor away from the outer reactor wall which in standard commercial use is constantly heated. Heat energy recovery from a reactor of the present invention is also possible in a reactor system comprising reactors as, for example, those outlined below. 
       Reactor 
       [0026]      FIG. 1  is an illustrative schematic diagram showing a reactor  100  according to one embodiment. The reactor  100  has an outer reactor  102  for withstanding a reaction pressure of a reaction to be carried out within the reactor  100 . The outer reactor  102  is also adapted to withstand a reaction temperature of the reaction to be carried out within the reactor  100 . The reaction pressure for a typical devulcanization reaction is about 1500 psi and the reaction temperature for a typical devulcanization reaction can be as high as about 350° C. 
         [0027]    The reactor  100  has a reactor lid  104  sealably connected to the outer reactor  102 . Through the reactor lid  104  the interior of the reactor  100  can be accessed to, for example, retrieve reaction product, perform maintenance, install reaction vessels, input reaction solution, input heat transfer liquid, etc. Any suitable seal may be used which can withstand the temperature and pressure experienced by the outer reactor  102 . 
         [0028]    Within the outer reactor  102  is an inner vessel  106 . The inner vessel  106  is adapted to contain a reaction solution  112 , for example water, which can be heated. The inner vessel  106  is also adapted to contain at least one reaction vessel  110  for containing reactants to be reacted and reaction product which is generated. However, in standard use, a plurality of reaction vessels  110  will be situated in the inner vessel  106  and in the reaction solution  112 . The reaction vessels  110 , depending on their structure may be either fully submerged or partially submerged in the reaction solution  112 . A space between the outer reactor  102  and the inner vessel  106  may be filled with either an inert gas (optionally pressurized), a heat transfer liquid for transmitting heat from the outer reactor  102  to the inner vessel  106  or insulation. Any liquid in the space may be removed via an outer reactor outlet  124  in a cooling phase of the reaction thereby isolating the inner vessel  106  from the outer reactor  102 . This allows for cool-down of the inner vessel  106  without the need for cooling the outer reactor  102 . 
         [0029]    During cool-down of the reactor  100 , high pressure vapour may be exhausted from the outer reactor  102 . When this is done, the pressure in the reactor  100  is reduced and liquid in the inner vessel  106  begins to boil and evaporate. This evaporation causes cooling of the inner vessel  106  and the reaction solution  112  therein as well as the reaction vessels  110  therein. However, evaporation and boiling of the reaction solution  112  can lead to spillage of the reaction solution  112  into the outer reactor  102 . In order to prevent spillage of the reaction solution  112  into the outer reactor  102  a splatter shield  108  is used. The splatter shield  108  and the inner vessel  106  work in combination to contain the reaction solution  112 , however, the combination is not sealed from the outer reactor  102  but is open to the outer reactor  102  and the reaction pressure within the reactor is equalized between the inner vessel  106  and the outer reactor  102 . Additionally, vapour injected into the inner reactor  106  may also pass to the outer reactor  102  between the splatter shield  108  and the inner vessel  106 , as will be discussed in more detailed below. 
         [0030]    In order to allow for quicker cool-down of the reaction vessels  110  in the inner vessel  106  without the need for cooling the outer reactor  102 , which has a large thermal mass and would therefore require a long time to cool down and a large amount of heat energy to re-heat following cool-down, the inner vessel  106  is additionally heated by a second heat source. A vapour injector  114  having a nozzle outlet positioned in the inner vessel  106  provides for heating vapour  116  for heating the reaction solution  112  in the inner vessel  106 . The vapour injector  114  is submerged in the reaction solution  112  and is generally located below the reaction vessels  110 . The vapour injector  114  will inject vapour  116  into the reaction solution  112 . The injection of vapour  116  using the vapour injector  114  provides a convenient method of mixing the solution in the inner vessel  106  and maintaining a substantially uniform temperature throughout the liquid. To optimize the heating and mixing of the solution in the inner vessel  106 , the injector  114  and the nozzle outlet may distribute the injection of the vapour  116  substantially over the entire cross-section of the inner vessel  106  or a majority of the cross-section of the inner vessel  106  to optimize the condensation of the vapour in the liquid. 
         [0031]    The reactor may be pressurized with an inert gas to facilitate the condensation of the vapour  116  in the inner vessel  106 . 
         [0032]    A reaction solution outlet  122  may be used for draining the reaction solution  112  from the inner vessel  106  when the inner vessel  106 . This can be done either following cool-down of the reactor  100  in order to empty the inner vessel  106 . Alternatively, this can be done during cool-down, and the heated reaction solution  112  can be stored and the pre-heated solution can be reused thereby reducing the amount of heat energy required to heat the reused reaction solution to reaction temperatures. When done during cool-down, cooling water must be added to the inner vessel  106  to reduce the temperature of the reaction vessels  110  for their removal from the reactor  100 . Depending on the type of reaction vessel  110  used, the reaction solution  112  may contain reaction product in which case the reaction solution outlet  122  may direct the reaction solution  112  to a collection device for collecting any reaction product in the reaction solution. 
         [0033]    Additionally, the reaction solution outlet  122  may not be a separate element of the reactor  100  but may be incorporated into the vapour injector  114 . 
         [0034]    A typical reaction cycle using a reactor  100 , such as that described above, involves the constant heating of the outer reactor  102 . As outlined above, the outer reactor  102  is a large thermal mass and therefore it is advantageous to maintain the outer reactor  102  at a substantially high temperature and near the reaction temperature. Heat applied to the outer reactor  102  is radiated to the inner vessel  106  usually using a heat transfer liquid. Reaction solution  112  is pumped into the inner vessel after placement of the reaction vessels  110 . The reaction solution  112  is heated via the outer reactor  102 . Additional heat is provided in the form of vapour  116  through the vapour injector  114  to heat the reaction solution  112  to the reaction temperature. Upon completion of the reaction the reaction may be cooled so that the reactor lid  104  may be opened and the reaction product can be retrieved. Cool-down of the reaction is carried out first by draining any liquid in the outer reactor  102 . The high pressure vapour is then exhausted from the reactor  100  via outlet  118  thereby causing evaporation and cooling of the reaction solution  112  in the inner vessel  106 . By doing so, the inner vessel  106  and the reaction vessels  110  are isolated from the outer reactor  102  and thus the heat which is constantly applied to the outer reaction  102  thereby allowing for a quicker cool-down of the reaction product. Once the pressure in the reactor  100  has substantially equalized with the outside atmospheric pressure, the temperature of the interior of the reactor is usually suitable for opening of the reactor lid  104  and retrieval of the reaction vessels  110 . Exhausted vapour may be reused as discussed below with reference to  FIG. 2 . 
         [0035]    The reaction vessels  110  generally have an open structure such as a wire basket, perforated metal or the like. The reaction vessels  110  may be sealed from the reaction solution  112  and may simply be heated by the reaction solution  112 . Additionally, the reaction vessels  110  may contain the reactants and reaction products in the reaction vessel  110  itself, separate from the liquid in the inner reactor (i.e. the reaction vessel  110  is completely sealed or vented through a hole at the top versus a wire cage). This keeps almost all the contamination inside the reaction vessel  110  and corrosion resistant materials become more of an issue for the reaction vessels  110  than the inner reactor  106 . It also becomes easier to add various chemicals to facilitate the reaction without affecting the reactor, valves, etc. When using a reaction vessel  110  having a hole at the top, the reaction vessel  110  is only partially submerged in the reaction solution  112  so that heat is radiated into the reaction vessel  110  and most of the contaminates in the reaction vessel  110  do not leak out and contaminate the reaction solution  112  and the inner vessel  106 . It will be apparent to one skilled in the art that the invention is not limited to the number of reaction vessels  110  that are located within the inner vessel  106 . 
         [0036]    The inner vessel  106  may be made out of a number materials to prevent corrosion based on the type of reaction to be carried out therein as well as the reaction temperatures. For example, the inner vessel  106  may be made from Inconel® Ni—Cr, Ni—Cr—Fe, and Ni—Cr—Mo alloys or Monel® Ni—Cu alloys. These are only two out of a range of materials that offer some corrosion resistance for the inner vessel if it is required. At lower reaction temperatures, the inner vessel  106  may be made from plastic, while at higher temperatures stainless steel may be used. If corrosion is not a big concern, carbon steel may be used. One of skill in the art will understand that many types of material and thicknesses of material may be used for withstanding temperature, pressure and corrosion based on the reactions to be carried out in the reactor  100 , the life expectancy of the reactor and the budget for the reactor  100 . 
         [0037]    Additionally, the reaction vessels  110  may be made of the corrosion and pressure resistant materials outlined above. 
       Reactor System 
       [0038]      FIG. 2  is an illustrative schematic diagram of one embodiment of a reactor system  200  according to one aspect of the present invention. The reactor system  200  comprises a plurality of reactors  202 ,  204 ,  206 ,  208  and  210  such as that outlined above with reference to  FIG. 1 . Additionally, the reactor system  200  may comprise a reaction solution reservoir  212  for containing reaction solution to be used in the reactors of the reactor system  200 . The reaction solution may be, for example, water or another suitable solution. High pressure vapour from each of the reactors  202 ,  204 ,  206 ,  208  and  210  may be transferred between the reactors and the reservoir  212  through the outlet  118  in the reactors via a manifold  214  which distributes the vapour to the desired reactor for injection via the vapour injector for reuse in heating reaction solution. 
         [0039]    When used in a reactor system  200  comprising the plurality of reactors  202 ,  204 ,  206 ,  208  and  210 , such as reactor  100  described above, the exhausted vapour may be distributed via a manifold  214  to either another of the plurality of reactors and reused to heat the reaction solution of the that reactor and/or can be used to heat a reservoir  214  containing reaction solution to be used in a reaction. 
         [0040]    In the reactor system  200 , once a reaction is complete and a cool-down phase is desired, any liquid in the outer reactor  102  is removed using, for example, an outer reactor outlet  124 . The high pressure vapour is then exhausted out of the first reactor through the outlet  118  and through the manifold  214  to another of the reactors until the pressure between the reactors is equalized. As outlined above, this process causes evaporation and cooling in the first reactor. The reactor pressure in the first reactor will still be above atmospheric pressure and therefore remaining high pressure vapour from the first reactor, in which the cool-down phase is in effect, may be applied to the reaction solution reservoir thus relieving the remaining pressure in the first reactor until the pressure is reduced to substantially atmospheric pressure and the temperature of at least the inner reactor  106  is below about 100° C. and the reactor lid  104  may be opened. 
         [0041]    In this manner, heat energy is preserved as the vapour is reused to heat both the reaction solution of another reactor as well as reaction solution in the reservoir  212 . Less heat energy is required to be transmitted through the outer reactor  102  to heat the inner vessel  106  of the reactor  100 . The reaction solution  112  is thereby heated more quickly and more efficiently using such a reactor system. Additionally, because the inner vessel  106  and the reaction vessels  110  therein are isolated from the outer reactor  102  and the heat transmitted therethrough, they may be cooled down more quickly and effectively during the cool-down phase. 
         [0042]      FIG. 3  is an illustrative flowchart of a reaction process according to one embodiment of the invention using a multiple reactor system of high temperature high pressure reactors such as that described with reference to  FIG. 2 . An example of the reaction process will be described with regard to the flowchart of  FIG. 3 . 
         [0043]    In this example the reaction liquid is water, and reactor  1  is at 300° C. At step  300  it is determined whether the reaction is complete and reactor  1  is ready to proceed to the cooling phase. If the reaction is not complete the reaction is continued at step  302  until it is determined that the reaction should proceed to the cool-down phase. If the reactor is ready to be cooled it is determined if reactor  2  is ready to be heated at step  304 . For reactor  2  to be ready for heating it should have the reaction vessels in place and already be pre-heated to a temperature of approximately 150° C. using heating through the outer reactor  102 . If the reactor is not ready to be heated, the reactor is preheated at step  312 . When reactor  2  is ready for heating, high pressure vapour is vented from reactor  1  at step  306  and is provided to reactor  2  at step  308 . This can be done by exhausting vapour out of the reactor outlet  118  and directing the vapour to reactor  2  via the manifold  214 . By providing vapour from reactor  1  to reactor  2  the temperature of the inner vessel of reactor  2  can be increased from the pre-heating temperature of approximately 150° C. to approximately 225° C. as the steam condenses in the liquid in the inner vessel of reactor  2 . At the same time the venting of vapour causes liquid in the inner vessel of reactor  1  to evaporate thereby cooling the vessel from the reaction temperature of, for example, about 300° C. to about 225° C. 
         [0044]    At step  310  it is determined if the pressure in reactor  2  has been equalized with that in reactor  1 . If it has not been equalized the supply of vapour to reactor  2  is continued. Once the pressure in the two reactors has been equalized, remaining high pressure vapour in reactor  1  is exhausted and can be used to pre-heat another reactor from about 100° C. to about 150° C. or additionally or alternatively, any remaining vapour may be used to heat reaction solution in a reservoir for use in other reactors in step  314 . Venting the remaining high pressure vapour from reactor  1  reduces the pressure in reactor  1  to about atmospheric pressure and reduces the temperature of the reactor to below about 100° C. The reactor lid of reactor  1  may then be opened and the reaction product may be removed. 
         [0045]    In this way a considerable amount of heat energy is recovered. Heat energy is only then required to heat the inner vessel of reactor  2  from, for example about 225° C. to a reaction temperature of, for example, 300° C., and not the entire reactor from about 25° C. to about 300° C. Once the process of recovering energy has been completed (e.g. the inner vessel of reactor  2  is at about 225° C.) additional heat can be added by various means including injecting additional vapour into reactor  2  until it is at its operating temperature. An advantage of adding vapour is that the injection causes turbulence in the liquid, facilitates mixing, and produces a much more even temperature. 
         [0046]    In accordance with one embodiment of the invention, an example of an overall reaction process for one method of the devulcanization of rubber may comprise the following steps: 
         [0047]    1. Chop or grind tires or materials to be processed into pieces. 
         [0048]    2. Load into reaction vessels. 
         [0049]    3. Pre-heat processing/bulk liquid (e.g. up to 100° C.) with vapour as per step  314 . 
         [0050]    4. If using closed reaction vessels, add processing liquid (which can be different to the liquid in the inner vessel (e.g. liquid plus additives)) to the sample container. 
         [0051]    5. Load sample containers into inner vessel. 
         [0052]    6. With either open or closed sample containers add pre-heated reaction solution to the inner vessel. 
         [0053]    7. Close reactor lid. 
         [0054]    8. Pre-heat reaction solution with radiant heat via the outer reactor and/or recycled vapour from another reactor to preheat temperature (e.g. 100-150° C.). 
         [0055]    9. If required fill space between inner and outer vessel with liquid or heat transfer fluid. 
         [0056]    10. Add heating vapour (from separate source) to bring inner vessel to reaction temperature. 
         [0057]    11. Maintain temperature for required period. 
         [0058]    12. Exhaust vapour from the reactor via the outlet to reduce reactor temperature and pressure and provide reusable vapour to another reactor via the manifold. 
         [0059]    13. Once pressure of the reactors have equalized, relieve remaining pressure by using vapour from the reactor to preheat reaction solution reservoir. 
         [0060]    14. Remove the sample containers from the outer reactor. 
         [0061]    In an alternative embodiment the reaction solution may be an aqueous solution comprising a solute and a solvent, an organic liquid or a combination thereof. 
         [0062]    The samples could be vulcanized rubber or other material requiring high temperature and pressure processes. 
         [0063]    In a further alternative embodiment the rubber or other materials to be processed are in a sealed container, or vented container with the vented container having a certain size hole in it to equalize the pressure and control evaporation of the liquid in the container at the end of the cycle. This type of container can contain the reactants from the liquid in the inner vessel. In this embodiment additives may be used in the reaction solution that are contained within the sample containers themselves and kept away from the bulk liquid in the inner vessel. For example, additives to facilitate the devulcanization process and allow it to occur at lower temperatures or ensure reaction by-products are contained may be added to the sample containers. 
         [0064]    The present invention has been described with regard to a plurality of illustrative embodiments. However, it will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.