Fcc process for maximizing diesel

Abstract

A process is described for maximizing the FCC middle distillates comprising the use of two different converters, operating in a coordinated manner that seeks to maximize the production of LCO for diesel, generating a specified gasoline and reducing fuel oil production. Converter “A” operates with a low contact time in the riser, of 0.2 to 1.5 sec. (preferably from 0.5 to 1.0 sec.) making a higher reaction temperature possible even at low severity, from 510° C. to 560° C. (preferably from 530° C. to 550° C.) and with a catalyst suitable to the maximization of LCO. Converter “B” possesses a high activity catalytic system, suited to cracking naphtha and DO generated in the first converter. Preferably, converter “B” has two separate risers, allowing the reaction temperatures of each to be adjusted independently according to the range most recommended for maximizing the cracking of each of the streams: 530° C. to 560° C. for the DO riser and 540° C. to 600° C. for the naphtha riser. The high-quality LCO stream generated by cracking at low severity in converter “A” is not contaminated by the poorer quality LCO generated by re-cracking the DO in converter “B,” since each converter has its own fractionating tower. The use of low contact time as a route for reducing severity in converter “A” geared towards the production of better quality LCO allows it to operate with a higher reaction temperature for the same LCO conversion and quality level, entailing greater operating reliability for the unit, and providing benefits for the heat balance of the converter. In existing units, the improvement in the heat balance provides leeway to the air blower via increased batch temperature, and makes room for processing more residual batches.

1 . FCC PROCESS FOR MAXIMIZING DIESEL, comprising a converter “A” ( 1 ) operating at low severity, aiming the production of best quality LCO to be incorporated into the refinery diesel pool, and converter “B” ( 20 ) operating at high severity, wherein converters “A” ( 1 ) and “B” ( 20 ) operate in a coordinated manner with the converter “B” ( 20 ) receiving non-specified naphtha (NNE) ( 55 ) and decanted oil (DO) ( 58 ) generated in converter “A” ( 1 ), for the purpose of adjusting the production and quality profile of the other products of the process, achieving in converter “B” ( 20 ) a reduction of the fuel oil production, gasoline specification and recovery of LPG from the production. 
     
     
         2 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the feedstock ( 50   a ) for converter “A” ( 1 ) comprises heavy gas oil from distillation, heavy gas oil from coke, or atmospheric residue or a mix of these streams. 
     
     
         3 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the feedstock ( 50   b ) for the second converter comprises heavy gas oil from distillation, heavy gas oil from coke, or atmospheric residue or a mix of these streams. 
     
     
         4 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the converter “A” ( 1 ) comprises a riser “I” ( 2 ), a separator vessel ( 3 ), a rectifier ( 4 ) and a regenerator ( 6 ), with the catalyst flowing through standpipe ( 5 ) of rectifier ( 4 ) to regenerator ( 6 ) and through standpipe ( 7 ) of regenerator ( 6 ) to riser “I” ( 2 ). 
     
     
         5 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the low severity in converter “A” ( 1 ) entails the use of a contact time between batch and catalyst in riser “I” ( 2 ) in a range between 0.2 and 1.5 sec., preferably between 0.5 and 1.0 sec. 
     
     
         6 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the converter “B” ( 20 ) comprises a riser “II” ( 21 ), a riser “III” ( 28 ), a separator vessel ( 22 ), a rectifier ( 23 ), and a regenerator ( 25 ), with the catalyst flowing through standpipe ( 24 ) of rectifier ( 23 ) to regenerator ( 25 ) and through standpipe ( 26 ) of regenerator ( 25 ) to riser “II” ( 21 ) and through standpipe ( 27 ) of regenerator ( 25 ) to riser “III” ( 28 ), this being the preferred embodiment for converter “B” ( 20 ). 
     
     
         7 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the feedstock ( 50   c ) to be injected into riser “II” ( 21 ) converter “B” ( 20 ), comprises heavy gas oil from distillation, heavy gas oil from coke, or atmospheric residue or a mix of these streams. 
     
     
         8 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the converter “B” ( 40 ), alternatively, comprises a single riser ( 41 ), a separator vessel ( 42 ), a rectifier ( 43 ), and a regenerator ( 45 ), with the catalyst flowing through standpipe ( 44 ) of separator vessel ( 42 ) to regenerator ( 45 ) and through standpipe ( 46 ) of regenerator ( 45 ) to riser ( 41 ). 
     
     
         9 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the converters “A” ( 1 ) and “B” ( 20 ) generate reaction products that continue to the different fractionating towers, to fractionating towers “A” ( 11 ) and “B” ( 31 ) respectively. 
     
     
         10 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the converters “A” ( 1 ) and “B” ( 40 ) generate reaction products that continue to fractionating towers “A” ( 11 ) and “B” ( 33 ) respectively. 
     
     
         11 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein in converter “A” ( 1 ), a feedstock ( 50   a ) is injected into disperser ( 8 ) in a position higher than low severity riser “I” ( 2 ) (in maximum LCO operation) and, optionally, is injected into a disperser ( 9 ) at the base of riser “I”, providing flexibility to the refiner to change to the maximum gasoline mode. 
     
     
         12 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the cracking reactions in riser “I” ( 2 ) take place at a temperature between 510° C. and 560° C., preferably between 530° C. and 550° C., using a low activity catalyst suitable for maximizing the LCO. 
     
     
         13 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the reaction products ( 52 ) of converter “A” ( 1 ) are lighter hydrocarbons than the feedstock ( 50   a ), such as gasoline, LPG, fuel gas (FG) and LCO, plus the decanted oil (DO), and these are sent to a fractionating tower “A” ( 11 ), from which LCO stream ( 57 ) with suitable quality is removed for incorporation into the diesel pool. 
     
     
         14 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein at the top of fractionating tower “A” ( 11 ), a wet gas stream ( 54 ) and a non-specified naphtha (NNE) ( 55 ) stream is generated, that is separated into a top vessel ( 12 ). 
     
     
         15 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the NNE fraction ( 55 ) is sent to the base of a, high severity, riser “II” ( 21 ), constituting part of second converter “B” ( 20 ); and alternatively an NNE fraction ( 56 ) is sent to the “lift” section of riser “I” ( 2 ), constituting part of first converter “A” ( 1 ). 
     
     
         16 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the NNE fraction ( 55 ) is sent to the base (area of high severity) of a riser ( 41 ), constituting part of second converter “B” ( 40 ); and alternatively an NNE fraction ( 56 ) is sent to the “lift” section of riser “I” ( 2 ), constituting part of first converter “A” ( 1 ). 
     
     
         17 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the DO stream ( 58 ) exits the bottom of a fractionating tower “A” ( 11 ) a DO stream ( 58 ) exits and is sent to the base of a riser “III” ( 28 ) of converter “B” ( 20 ). 
     
     
         18 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein a DO current ( 58 ) exits the bottom of a fractionating tower “A” ( 11 ), and is sent to a disperser ( 48 ) located above a disperser ( 47 ) for injecting NNE ( 55 ), into riser ( 41 ) of converter “B” ( 40 ). 
     
     
         19 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the reaction products ( 61 ) of converter “B” ( 20 ) are sent to a fractionating tower “B” ( 31 ) from which an LCO stream ( 65 ) for fuel oil diluent exits. 
     
     
         20 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the reaction products ( 68 ) of converter “B” ( 40 ) are sent to a fractionating tower “B” ( 33 ) from which an LCO stream ( 72 ) for fuel oil diluent exits. 
     
     
         21 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein a wet gas stream ( 63 ) and an non-stabilized naphtha stream with quality for gasoline ( 64 ) are generated at the top of fractionating tower “B” ( 31 ), and are separated in a top vessel ( 32 ). 
     
     
         22 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1  wherein a wet gas stream ( 70 ) and an non-stabilized naphtha stream with quality for gasoline ( 71 ) are generated at the top of fractionating tower “B” ( 33 ), and are separated in a top vessel ( 34 ). 
     
     
         23 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein DO ( 66 ) with specification for aromatic residue (DO for RARO) is generated at the top of fractionating tower “B” ( 31 ). 
     
     
         24 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein DO ( 73 ) with specification for aromatic residue (DO for RARO) is generated at the bottom of fractionating tower “B” ( 33 ). 
     
     
         25 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the fraction of wet gases ( 63 ) exiting from the top ( 32 ) joins a wet gas stream ( 54 ) from converter “A” ( 1 ) and continues to a common gas recovery area, or alternatively to two different gas recovery areas, if there are such. 
     
     
         26 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the fraction of wet gases ( 70 ) exiting from the top ( 34 ) joins a wet gas stream ( 54 ) from converter “A” ( 1 ) and continues to a common gas recovery area, or alternatively to two different gas recovery areas, if there are such. 
     
     
         27 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the non-specified naphtha (NNE) ( 55 ) and the decanted oil (DO) ( 58 ), both removed from fractionating tower “A” ( 11 ), will be sent for re-cracking in converter “B” ( 20 ), which has two independent risers, riser “II” ( 21 ) and riser “III” ( 28 ), the first being for cracking NNE ( 55 ) and the second for cracking DO ( 58 ). 
     
     
         28 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the non-specified naphtha (NNE) ( 55 ) and the decanted oil (DO) ( 58 ), both removed from fractionating tower “A” ( 11 ), will be sent for re-cracking in converter “B” ( 40 ), which has a single riser ( 41 ), in which NNE ( 55 ) is cracked in its “lift” section and DO ( 58 ) is cracked in the upper section. 
     
     
         29 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein converter “B” ( 20 ) has an alternative to processing fresh feedstock ( 50   b ) in the same disperser ( 30 ) used for DO ( 58 ), or in another disperser level in riser “III” ( 28 ). 
     
     
         30 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein converter “B” ( 40 ) has an alternative to processing fresh feedstock ( 50   b ) in the same disperser ( 48 ) used for DO ( 58 ), or in another disperser level in riser ( 41 ). 
     
     
         31 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein converter “B” ( 20 ) has an alternative to processing fresh feedstock ( 50   c ) in the same disperser ( 35 ) of riser “II” ( 21 ), if the operating mode of converter “A” ( 1 ) is changed to maximization of Gasoline. 
     
     
         32 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein converter “B” ( 20 ) has high activity catalytic system, suitable to cracking NNE ( 55 ) and DO ( 58 ) and different from the low activity catalytic system used in converter “A” ( 1 ) for cracking a feedstock ( 50   a ). 
     
     
         33 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein converter “B” ( 40 ) has high activity catalytic system, suitable to cracking NNE ( 55 ) and DO ( 58 ) and different from the low activity catalytic system used in converter “A” ( 1 ) for cracking the feedstock ( 50   a ). 
     
     
         34 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , comprising two independent risers in converter “B” ( 20 ), which allows the reaction temperatures of each to be adjusted according to the most recommended range to maximize the cracking of the NNE ( 55 ) and DO ( 58 ) streams in each one of them, this being the preferred embodiment for cracking these streams. 
     
     
         35 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein riser “II” ( 21 ) operates with a reaction temperature between 540° C. and 600° C. 
     
     
         36 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein riser “III” ( 28 ) operates with a reaction temperature between 530° C. and 560° C. 
     
     
         37 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , comprising it has a single riser ( 41 ) in converter “B” ( 40 ) that operates at a reaction temperature between 530° C. and 570° C., with the cracking of NNE ( 55 ) being done in the “lift” section at the base of riser ( 41 ) and the cracking of DO ( 58 ) being done at a higher point. 
     
     
         38 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein riser “III” ( 28 ) for re-cracking DO ( 58 ) operates with a high reaction temperature and contact time, meeting the objective of reducing DO production, but generating some amount of poorer quality LCO ( 65 ). 
     
     
         39 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein riser ( 41 ) for re-cracking NNE ( 55 ) and DO ( 58 ) operates with high reaction temperature and contact time, meeting the objective of reducing DO production, but generating some amount of poorer quality LCO ( 72 ). 
     
     
         40 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the poorer quality LCO ( 65 ) generated by re-cracking DO ( 58 ) in converter “B” ( 20 ) is isolated from the high quality LCO ( 57 ) produced in the cracking of the feedstock ( 50   a ) at low severity in converter “A” ( 1 ). 
     
     
         41 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein poorer quality LCO ( 72 ) generated by re-cracking DO ( 58 ) together with NNE ( 55 ) in riser ( 41 ) of converter “B” ( 40 ) is isolated from the high quality LCO ( 57 ) produced in the cracking of the feedstock ( 50   a ) at low severity in converter “A” ( 1 ). 
     
     
         42 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , comprising a gas recovery area ( 36 ) where fractions of fuel gas, ( 74 ), LPG ( 75 ) e Gasoline ( 76 ) are produced. 
     
     
         43 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , wherein the flow of the reactive catalyst/oil mixture in any of the converters is downwards. 
     
     
         44 . FCC PROCESS FOR MAXIMIZING DIESEL, according to  claim 1 , which can be applied to an existing FCC unit.