Methods and processes for moving towards optimizing one or more parameters in a parallel train comprising two hydrocarbon cracking facilities where the two facilities either have non-identical process unit configurations or are operating under non-identical process conditions are disclosed. These methods and processes use models to simulate the impact of interconnecting the facilities by partially withdrawing an intermediate stream from within one cracking facility and adding the partially withdrawn stream to the second cracking facility in order to better optimize the overall operation of the parallel train.

The invention concerns a process and a facility for reducing the concentration of heavy polycyclic aromatic compounds (HPNA) in the recycle loop of hydrocracking units, which comprises a fractionation column. In accordance with this process, a portion of the stream present at the level of at least one plate located between the plate for supplying hydrocracked effluent and the plate for withdrawing the distillate fraction which is the heaviest is withdrawn from the fractionation column and at least a portion of said withdrawn stream is recycled to the column directly or after optional liquid separation, and optionally a portion of said withdrawn stream is recycled to the hydrocracking step directly or after optional gas separation.

The invention concerns a process and a facility for reducing the concentration of heavy polycyclic aromatic compounds (HPNA) in the recycle loop of hydrocracking units, which comprises a fractionation column. In accordance with this process, a portion of the stream present at the level of at least one plate located between the plate for supplying hydrocracked effluent and the plate for withdrawing the distillate fraction which is the heaviest is withdrawn from the fractionation column and at least a portion of said withdrawn stream is recycled to the column directly or after optional liquid separation, and optionally a portion of said withdrawn stream is recycled to the hydrocracking step directly or after optional gas separation.

Process and apparatus for producing a naphtha stream is provided. The process comprises providing a kerosene stream to a hydrocracking reactor. The kerosene stream is hydrocracked in the presence of a hydrogen stream and a hydrocracking catalyst in the hydrocracking reactor at hydrocracking conditions comprising a hydrocracking pressure, a hydrocracking temperature, and a liquid hourly space velocity at a net conversion of at least about 90%, to provide a hydrocracked effluent stream comprising liquefied petroleum gas, heavy naphtha fraction and light naphtha fraction. One or more of the hydrocracking conditions are adjusted to maintain a ratio of the light naphtha fraction to the heavy naphtha fraction of at least about 2 by weight, suitably at least about 2.2 and preferably at least about 2.5 in the hydrocracked effluent stream while maintaining the net conversion of at least about 90%.

Systems and methods are provided for detecting abnormal temperature conditions within a fixed bed reactor. In a fixed bed reactor, a hydrocarbon (or hydrocarbon-like) feedstock can be exposed to one or more types of catalyst particles at elevated temperatures and/or pressures. In addition to the one or more types of catalyst particles, a plurality of temperature-sensor structures can be included in a catalyst bed and/or a coating including one or more temperature-sensor structures can be provided on an interior wall or other interior surface in the reactor. The temperature-sensor structures can have a threshold temperature at which the temperature-sensor structure changes to allow introduction and/or release of a detectable substance.

Systems and methods are provided for detecting abnormal temperature conditions within a fixed bed reactor. In a fixed bed reactor, a hydrocarbon (or hydrocarbon-like) feedstock can be exposed to one or more types of catalyst particles at elevated temperatures and/or pressures. In addition to the one or more types of catalyst particles, a plurality of temperature-sensor structures can be included in a catalyst bed and/or a coating including one or more temperature-sensor structures can be provided on an interior wall or other interior surface in the reactor. The temperature-sensor structures can have a threshold temperature at which the temperature-sensor structure changes to allow introduction and/or release of a detectable substance.

A process id disclosed for upgrading tars, typically those resulting from hydrocarbon refining processes, to products suitable for other uses, such as blending with other hydrocarbons to provide low-sulfur fuel oils or Emission Control Area-acceptable fuels. A low-sulfur hydrocarbon product obtained from the process is also disclosed.

The invention relates to a method for optimizing layered catalytic processes. This is accomplished by testing various catalysts with a compound found in a feedstock to be tested, to determine the facility of the catalyst in hydrogenating, hydrosulfurizing, or hydrodenitrogenating the molecule, and hence the feedstock. In a preferred embodiment, the Double Bond Equivalence of the feedstock and molecule are determined, and catalysts are pre-selected based upon their known ability to work with materials of this DBE value. In preferred embodiments, the layered catalysts include a demetallization catalyst, used before hydrocracking. In additional preferred embodiments, the test feedstock contains 500 ppmw or less asphaltenes, preferably C.sub.5-asphaltenes.

The invention relates to a method for optimizing layered catalytic processes. This is accomplished by testing various catalysts with a compound found in a feedstock to be tested, to determine the facility of the catalyst in hydrogenating, hydrosulfurizing, or hydrodenitrogenating the molecule, and hence the feedstock. In a preferred embodiment, the Double Bond Equivalence of the feedstock and molecule are determined, and catalysts are pre-selected based upon their known ability to work with materials of this DBE value. In preferred embodiments, the layered catalysts include a demetallization catalyst, used before hydrocracking. In additional preferred embodiments, the test feedstock contains 500 ppmw or less asphaltenes, preferably C.sub.5-asphaltenes.

A process is disclosed for shifting the product of a hydrocracker in a hydrocarbon refinery back and forth from a more naphtha focused product slate to a more diesel focused product slate to take advantage of price and demand shifts between gasoline and diesel by using a naphtha selective catalyst and temporarily passivating the catalyst with a basic material such as ammonia in the hydrocracker. The ammonia passivates the acid catalyst sites on the catalyst and produces more total liquids and more diesel with attractive cold flow and pour point properties for a temporary period. When implemented in a temporary manner and the flow of ammonia is suspended the hydrocracker product slate returns to a more gasoline focused slate.