Patent Publication Number: US-2018043326-A1

Title: Ultra low pressure continuous catalyst transfer with lock hopper

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of copending International Application No. PCT/US2016/036797 filed Jun. 10, 2016 which application claims benefit of U.S. Provisional Application No. 62/183,922 filed Jun. 24, 2015, now expired, the contents of which cited applications are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to solids transfer equipment. In particular, the invention is directed to the low pressure transfer of catalyst particles between reactors, or a reactor and a regenerator. 
     BACKGROUND 
     Many modern chemical processes utilize catalysts for the conversion of a feedstock to a more valuable product stream. Catalysts have a limited life of operation before a need for the regeneration of the catalyst. In many chemical operations, the process involves passing a catalyst between a reactor to a regenerator and back again to provide for a long continuous operation. 
     However, a continuous catalyst regeneration technology in use today does not provide for a continuous constant rate of catalyst circulation. The process today involves the use of lock hoppers and lift engagers to circulate catalyst in small batches to provide for a semi-continuous process. This batch-wise catalyst transfer process can lead to catalyst bridging and the plugging of catalyst transfer lines. 
     There is a need to improve the process and equipment for the transfer of catalyst in a continuous catalyst regeneration system. 
     SUMMARY 
     The present invention is an improvement for the low pressure transfer of solids in chemical reactor equipment. 
     A first embodiment of the invention is an apparatus for the transfer of catalyst comprising a vessel from a terminal reactor having an inlet and an outlet; a non-mechanical valve having a catalyst inlet in fluid communication with the vessel outlet, at least one lift gas inlet, and an outlet; a transfer line having an inlet in fluid communication with the non-mechanical valve outlet, and an outlet; a first downstream vessel having an inlet in fluid communication with the transfer line, and a gas outlet and a catalyst outlet; a second downstream vessel having an inlet in fluid communication with the first downstream vessel outlet; and an outlet; and a third downstream vessel having an inlet in fluid communication with the second downstream vessel outlet, and an outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising an impactless elbow disposed in the transfer line and at a position in the transfer line at an elevated position relative to the first downstream vessel. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the transfer line further includes a second inlet for admitting a second lift gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the second inlet is in a position in the transfer line disposed below the inlet from the non-mechanical valve outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising; a second non-mechanical valve having an inlet in fluid communication with the third downstream vessel outlet, a lift gas inlet and an outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a second transfer line having an inlet in fluid communication with the second non-mechanical valve outlet, and an outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a second impactless elbow disposed in the second transfer line and at a position in the transfer line at an elevated position relative to a fourth downstream vessel. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the second transfer line further includes a second inlet for admitting a second lift gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the second inlet is in a position in the second transfer line disposed below the inlet from the second non-mechanical valve outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the non-mechanical valve comprises a horizontal length of pipe having a first inlet for admitting catalyst particles, a second inlet for admitting a lift gas, and an outlet. 
     A second embodiment of the invention is an apparatus for the transfer of catalyst from a reactor to a regenerator, comprising a first vessel from a terminal reactor having an inlet and an outlet; a first non-mechanical valve having a catalyst inlet in fluid communication with the first vessel outlet, a lift gas inlet, and an outlet; a first transfer line having an inlet in fluid communication with the first non-mechanical valve outlet, and an outlet; a first downstream vessel having an inlet in fluid communication with the first transfer line, and a gas outlet and a catalyst outlet; a second downstream vessel having an inlet in fluid communication with the first downstream vessel outlet; and an outlet; a third downstream vessel having an inlet in fluid communication with the second downstream vessel outlet, and an outlet; a second non-mechanical valve having an inlet in fluid communication with the third downstream vessel outlet, a lift gas inlet and an outlet; and a second transfer line having an inlet in fluid communication with the second non-mechanical valve outlet and an outlet in fluid communication with a downstream vessel regenerator. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the first transfer line further includes a second inlet for admitting a second lift gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the second inlet is in a position in the first transfer line disposed below the inlet from the first non-mechanical valve outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the non-mechanical valve comprises a horizontal length of pipe having a first inlet for admitting catalyst particles, a second inlet for admitting a lift gas, and an outlet. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the second transfer line further includes a second inlet for admitting a second lift gas. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the second inlet is in a position in the second transfer line disposed below the inlet from the second non-mechanical valve outlet. 
     A third embodiment of the invention is a process for transferring catalyst from a reactor to another reactor, comprising passing catalyst from a first vessel to a non-mechanical valve; passing a lift gas to the non-mechanical valve to carry the catalyst to a transfer line; passing a lift gas to the transfer line to lift the catalyst up the transfer line; and passing the lifted catalyst to a first downstream vessel; wherein the pressure at the inlet to the non-mechanical valve is at least 10 kPa (gauge). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the pressure at the inlet to the non-mechanical valve is at least 7 kPa (gauge). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the pressure at the inlet to the non-mechanical valve is at least 4 kPa (gauge). An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the lift gas comprises hydrogen 
     Other objects, advantages and applications of the present invention will become apparent to those skilled in the art from the following detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is the apparatus for transferring catalyst from a terminal reactor to a catalyst regenerator; and 
         FIG. 2  is the apparatus for transferring catalyst between an upstream reactor and a downstream reactor. 
     
    
    
     DETAILED DESCRIPTION 
     In a current olefin conversion process, a continuous catalyst regeneration (CCR) technology is used the utilizes a batch-wise transfer system, wherein small amounts of catalyst are collected and then transferred. This utilizes equipment, such as lock hoppers and lift engagers and complex valving for the transfer of catalyst from a reactor to a regenerator. The transfer of catalyst through this equipment is subject to catalyst plugging of transfer lines and valves, and the attrition of the catalyst as the catalyst is eroded in the transfer process. 
     The present invention allows for a reduced catalyst plugging and reduced catalyst attrition. The apparatus also provides for a continuous flow to a catalyst regenerator for a more consistent operation of the regenerator. In particular, in the current Oleflex™ technology, catalyst flows from the annular space between the Oleflex reactor screens through a series of catalyst transfer pipes into an external catalyst collector. From the catalyst collector, the catalyst then flows into a lift engager, where the catalyst batch is lifted into the top of the next reactor. In the final Oleflex reactor, a lock hopper is located between the catalyst collector and a lift engager; the lock hopper is used to change catalyst atmospheres from hydrogen/hydrocarbon environment to a nitrogen environment so that the catalyst can be safely regenerated. Similarly, in the catalyst lift from the CCR regenerator to the first Oleflex reactor, a lock hopper is used upstream of the lift engager to change from a nitrogen atmosphere to a hydrogen atmosphere before the catalyst enters the first reactor. 
     The batch lifting of catalyst through the system necessitates the use of higher catalyst velocities that would be required for constant-rate catalyst circulation. In addition, the complex valving required for the lock hoppers and lift engagers coupled with the higher catalyst velocity result in increased catalyst attrition rates. 
     The present invention is an apparatus for the transfer of catalyst. The transfer is from a reactor to a regenerator. As shown in  FIG. 1 , the apparatus includes a vessel  10  from a terminal reactor, wherein the vessel  10  has a catalyst inlet  12  and a catalyst outlet  14 . The vessel  10  can also be a part of the terminal reactor where catalyst is collected as it leaves the reactor catalyst bed. This would be typically from a moving bed reactor wherein the catalyst flows down an annular reactor bed. The apparatus further includes a non-mechanical valve  20  having a catalyst inlet  22  in fluid communication with the catalyst outlet  14  from the vessel  10 , and a catalyst outlet  24 . A transfer line  30  has an inlet  32  that connects to the non-mechanical valve catalyst outlet  24 , and a transfer line outlet  34 . The apparatus further includes a first downstream vessel  40  having an inlet  42  in fluid communication with the transfer line outlet  34 , and the first downstream vessel  40  has a gas outlet  44  and a catalyst outlet  46 . The apparatus further includes a second downstream vessel  50  having an inlet  52  in fluid communication with the first downstream vessel outlet  46 , and an outlet  54 , and a third downstream vessel  60  having an inlet in fluid communication with the second downstream vessel outlet  54  and an outlet  64 . 
     In order to minimize catalyst erosion, or attrition, the apparatus can include an impactless elbow  38  attached to the transfer line outlet  34 . The transfer line  30  is oriented to elevate catalyst from the non-mechanical valve  20  to the first downstream vessel  40 , and is oriented such that the outlet  34  has an elevation greater than the inlet  32 . Typically, the transfer line will have a vertical orientation. The transfer line  30  can further include a second inlet  36  for admitting a second lift gas stream. The position of the second inlet  36  in the transfer line  30  is below the inlet  32  from the non-mechanical valve outlet  24  for providing additional lifting gas to carry the catalyst particles to the outlet  34  of the transfer line  30 . 
     The apparatus can further include a second part for a further transfer of catalyst to the regenerator  100 . The second part includes a second non-mechanical valve  70  having an inlet  72  in fluid communication with the third downstream vessel outlet  64 , a lift gas inlet  74  to the valve and an outlet  76 . The second part further includes a second transfer line  80  having an inlet  82  in fluid communication with the second valve outlet  76 , and a second transfer line outlet  84 . The second transfer line  80  can further include a second inlet  86  for admitting a second lift gas stream. 
     A second impactless elbow  90  has an inlet in fluid communication with the second transfer line outlet  84  and the second transfer line  80  is oriented with a vertical orientation where the outlet  84  is elevated above the inlet  82 . The second impactless elbow  90  has an outlet  92  and is disposed in a position elevated above a fourth downstream vessel  100 . In this particular embodiment, the fourth downstream vessel is the regenerator. 
     An impactless elbow is a device for receiving a flowing fluid carrying solid particles, and has an expanded diameter to allow the fluid to slow and have the particles slow down or even settle out without having to impact the walls of the device. An impactless elbow can be a pipe with an enlarged diameter and curved to redirect the flow without having the catalyst particles impinging on the walls of the elbow. This reduces attrition of the catalyst. 
     The non-mechanical valve  20 ,  70  is a system for transferring a flowing solid with a fluid. The valve comprises a horizontal length of conduit, or piping, having an inlet for the solid particles to be carried in, and a second inlet for a fluid to carry the particles. The fluid can be a lifting gas. The conduit includes an outlet for the flowing fluid with the particles. The outlet to the non-mechanical valve carries the flowing fluid with the particles to a transfer line  30 ,  80 , wherein the particles are transferred to an elevated position and allowed to flow by gravity to a receiving vessel. 
     The particles are allowed to flow in a continuous manner to with a continuous flowing lift gas to provide a smoother, more consistent and continuous transfer of particles between vessels without moving parts. 
     In one embodiment, the first downstream vessel  40  comprises a disengaging drum where the lift gas and catalyst particles are separated. The disengaging drum allows the particles to settle out from the lift gas by slowing the flow sufficiently that the particles are no longer able to be carried by the lift gas. The disengaging drum has an outlet for the gas without the particles and a second outlet for the particles. In this embodiment, the second downstream vessel  50  is a lock-hopper for transferring the particles through a gravity driven mode to a higher pressure. A lock-hopper is a vessel with an entrance valve to form a pressure tight seal and an exit valve to form a pressure type seal. The entrance valve and exit valve are open and closed alternately such that both are not in an “open” state at the same time. This allows the transfer from one vessel above the lock-hopper to another vessel below the lock-hopper. The lock-hopper can include the ability to pressurize the lock-hopper to allow for transfer from a lower pressure vessel to a higher pressure vessel. In this embodiment, the third downstream vessel is a surge drum to allow collection of batches of catalyst and provide for a continuous flow of catalyst to the second non-mechanical valve. 
     In another embodiment as shown in  FIG. 2 , the apparatus can be a catalyst transfer system for transferring catalyst between reactors in series. The apparatus for transfer of catalyst comprises a first catalyst feeder conduit  110  having an inlet  112  for receiving catalyst from an upstream reactor, and an outlet  114 . The apparatus further includes a non-mechanical valve  120  having an inlet  122  in fluid communication with the first catalysts feeder conduit outlet  114 , a lift gas inlet  124 , and an outlet  126 . The apparatus further includes a transfer line  130  having an inlet  132  that is in fluid communication with the non-mechanical valve outlet  126  and a transfer line outlet  134 . The transfer line  130  can further include a second lift gas inlet  136  disposed below the inlet  132  in fluid communication with the non-mechanical valve outlet. The transfer line has a substantially vertical orientation with the transfer line outlet  134  at a higher elevation than the transfer line inlet  132 . The apparatus can include an impactless elbow  140  in fluid communication with the transfer line outlet  134 . The lift gas in a hydrocarbon processing unit can be hydrogen. 
     The apparatus can include a vessel for receiving catalyst from the upstream reactor, or the catalyst can collect in the bottom of the upstream reactor to be transferred by gravity to the first transfer conduit. 
     The non-mechanical valve and transfer line allow consistent and continuous transfer of catalyst from an upstream reactor to a downstream reactor, and for a lower pressure drop during the transfer. This provides one with the capability to transfer catalyst in a low pressure system without having to add a compressed gas for transferring the catalyst. The apparatus allows for transferring catalyst with as low as a 3.5 kPa-gauge pressure drop. 
     Another embodiment of the present invention is a process for transferring catalyst from an upstream reactor to a downstream reactor. The process includes passing catalyst from the upstream reactor to a non-mechanical valve, and passing a lift gas to the non-mechanical valve to generate a flow stream comprising the lift gas and catalyst. The flow stream is passed to a transfer line to lift the catalyst up the transfer line to generate a lifted catalyst. The lifted catalyst is passed to the downstream reactor, or vessel, wherein the pressure used to transfer the catalyst is less than 10 kPa (gauge). The pressure drop for passing the catalyst can be as low as 7 kPa, and as low as 4 kPa. 
     While the invention has been described with what are presently considered the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.