Apparatuses and methods for fluid catalytic cracking with limited particulate emissions

Abstract

Methods and apparatuses are provided for cracking a hydrocarbon. The method includes contacting a first hydrocarbon stream with a cracking catalyst in a riser. The cracking catalyst is regenerated in a regenerator to produce a flue gas stream having a particulate concentration, where the flue gas stream is vented. A second stream is contacted with the cracking catalyst in the riser while the first hydrocarbon stream is contacted with the catalyst, where the second stream includes a natural oil. The particulate concentration is a second particulate concentration while the second stream contacts the cracking catalyst, and a first particulate concentration prior to the second stream contacting the cracking catalyst. The first particulate concentration is greater than the second particulate concentration.

What is claimed is: 
     
         1 . A method of fluid catalytic cracking, the method comprising the steps of:
 contacting a first hydrocarbon stream with a cracking catalyst in a riser;   regenerating the cracking catalyst in a regenerator to produce a flue gas stream;   venting the flue gas stream, wherein the flue gas stream comprises particulates at a particulate concentration;   contacting a second stream with the cracking catalyst in the riser while contacting the first hydrocarbon stream with the cracking catalyst, wherein the second stream comprises a natural oil, and wherein the particulate concentration is a second particulate concentration while the second stream contacts the cracking catalyst, the particulate concentration is a first particulate concentration prior to the second stream contacting the cracking catalyst, and the second particulate concentration is less than the first particulate concentration.   
     
     
         2 . The method of  claim 1  where contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst wherein the second stream comprises about 50 to about 100 percent natural oil. 
     
     
         3 . The method of  claim 1  wherein contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst wherein the second stream comprises pyrolysis oil. 
     
     
         4 . The method of  claim 3  wherein contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst wherein the second stream comprises the pyrolysis oil without hydrotreating. 
     
     
         5 . The method of  claim 3  wherein contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst wherein the second stream comprises char. 
     
     
         6 . The method of  claim 1  wherein contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst wherein the second particulate concentration is about ninety weight percent or less of the first particulate concentration. 
     
     
         7 . The method of  claim 1  further comprising:
 introducing the first hydrocarbon stream to the riser in a first inlet; 
 introducing the second stream to the riser in a second inlet, wherein the second inlet is about 0.5 to about 12 meters above the first inlet on the riser. 
 
     
     
         8 . The method of  claim 1  further comprising:
 introducing the first hydrocarbon stream to the riser in a first inlet as a feedstock, wherein the first hydrocarbon stream comprises hydrocarbons; 
 introducing the second stream to the riser as the feedstock, wherein the second stream comprises about 0.5 to about 10 weight percent of the feedstock introduced to the riser. 
 
     
     
         9 . The method of  claim 1  further comprising:
 separating a riser effluent from the cracking catalyst in a riser catalyst separator, wherein the cracking catalyst comprises cracking catalyst fines; 
 entraining the cracking catalyst fines in the riser effluent; and 
 introducing the riser effluent to a fractionation zone. 
 
     
     
         10 . The method of  claim 1  further comprising:
 measuring the particulate concentration in the flue gas stream as an opacity; and wherein 
 contacting the second stream with the cracking catalyst comprises contacting the second stream with the cracking catalyst in the riser wherein the opacity of the flue gas decreases by about 50 percent or more when the second stream is contacting the cracking catalyst relative to the opacity prior to the second stream contacting the cracking catalyst. 
 
     
     
         11 . A method of fluid catalytic cracking, the method comprising the steps of:
 contacting a feedstock with a cracking catalyst in a riser to produce a riser effluent in a gaseous state, wherein the cracking catalyst comprises cracking catalyst fines having a diameter of about 0.04 millimeters or less; and   separating the riser effluent from the cracking catalyst in a riser catalyst separator, wherein about 25 weight percent or more of the cracking catalyst fines exit the riser catalyst separator with the riser effluent.   
     
     
         12 . The method of  claim 11  wherein contacting the feedstock with the cracking catalyst comprises contacting the feedstock wherein the feedstock comprises pyrolysis oil. 
     
     
         13 . The method of  claim 11  wherein contacting the feedstock with the cracking catalyst comprises:
 introducing a first hydrocarbon stream to the riser at a first inlet; and 
 introducing a second stream to the riser at a second inlet above the first inlet. 
 
     
     
         14 . The method of  claim 13  wherein introducing the first hydrocarbon stream to the riser comprises introducing the first hydrocarbon stream to the riser wherein the first hydrocarbon stream comprises a petroleum oil; and wherein
 introducing the second stream to the riser comprises introducing the second stream to the riser wherein the second stream comprises a natural oil. 
 
     
     
         15 . The method of  claim 13  wherein introducing the second stream to the riser comprises introducing the second stream to the riser at the second inlet, wherein the second inlet is about 0.5 to about 12 meters above the first inlet. 
     
     
         16 . The method of  claim 11  wherein contacting the feedstock with the cracking catalyst comprises contacting the feedstock with the cracking catalyst wherein the feedstock comprises a natural oil, wherein the natural oil is contacted with the cracking catalyst without any hydrotreating. 
     
     
         17 . The method of  claim 16  wherein contacting the feedstock with the cracking catalyst comprises contacting the feedstock with the cracking catalyst wherein the natural oil comprises about 90 to about 100 weight percent pyrolysis oil. 
     
     
         18 . The method of  claim 16  wherein contacting the feedstock with the cracking catalyst comprises contacting the feedstock with the cracking catalyst wherein the natural oil comprises char. 
     
     
         19 . The method of  claim 11  wherein separating the riser effluent from the cracking catalyst comprises separating the riser effluent from the cracking catalyst wherein about 50 weight percent or more of the cracking catalyst fines exit the riser catalyst separator with the riser effluent. 
     
     
         20 . A fluid catalytic cracking unit comprising:
 a riser;   a regenerator coupled to the riser;   a first inlet coupled to the riser, wherein the first inlet is configured to introduce a first hydrocarbon stream; and   a second inlet coupled to the riser, wherein the second inlet is about 0.5 to about 12 meters above the first inlet, and the second inlet is configured to introduce a second stream comprising a natural oil.