Columns hydrocracking

HCO is the sidecut stream from the main column that boils between LCO and decanted oil (DO). HCO is often used as a pumparound stream to transfer heat to the fresh feed and/or to the debutanizer reboiier. HCO is recycled to extinction, withdrawn as a product and processed in a hydrocracker, or blended with the decant oil. 

AGC-21 A process for converting natural gas to liquid fuels in three stages generation of syngas in a fluidized bed, Fischer-Tropsch synthesis in a slurry bubble column reactor, and hydrocracking. Piloted in 1997 and proposed for installation in Qatar. 

As a means of preparing high percentages of diesel fuels with good quality from the hydrocracked oil, a batch distillation of the oil was made in a packed laboratory distillation column in which a first fraction was removed at a corrected column head... 

Several of the commercial simulation programs offer preconfigured complex column rigorous models for petroleum fractionation. These models include charge heaters, several side strippers, and one or two pump-around loops. These fractionation column models can be used to model refinery distillation operations such as crude oil distillation, vacuum distillation of atmospheric residue oil, fluidized catalytic cracking (FCC) process main columns, and hydrocracker or coker main columns. Aspen Plus also has a shortcut fractionation model, SCFrac, which can be used to configure fractionation columns in the same way that shortcut distillation models are used to initialize multicomponent rigorous distillation models. 

The feedstocks (straight-mn naphtha (SRN) and a blend of SRN and hydrocracked naphtha) and hydrotreated products were analysed by ASTM methods for density, carbon, hydrogen, hydrocarbon and boiling point distribution. Total sulfur was determined by ASTM D-4045 method, mercaptan sulfur by the potentiometric method (ASTM D-3227 and UOP-212), disulfides by the UOP-202 method, polysulfides by polarography [1], and elemental sulfur by the UOP-286 method. The Perkin-Elmer gas chromatograph (Model 8700), equipped with a flame photometric detector (GC/FPD) and a DB-1 fused silica capillary column (30 m x 0.53 mm), was used for identification of individual sulfur compounds [2-6]. The sensitivity of the GC/FPD technique was maximized by optimizing the gas flow rates and temperature programming as presented elsewhere [1]. 

A stripped RD column could be applied in the hydrocracking and hydrotreating of petroleum to avoid excessive hydrocracking or hydrotreating of lighter products. " If the desired products are of higher molecular weight, a rectified RD column can be used. 

One example of a single variable control strategy is applied to a stripper in a hydrocracking unit. The main purpose of the stripper is to remove H2S and noncondensable components from the bottom product. One of the key indicators identified is the water dew point at the top of the stripper column. As a matter of fact, the dew point is a function of column overhead vapor composition and the amount of water. There was no monitoring capability available for the dew point temperature. If the column top temperature is lower than the dew point, the hydrogen sulfide will dissolve in the condensed water and cause corrosion to the column overhead system. 

A yield improvement option was identified from the hydrocracking unit (HCU) as a part of the energy optimization project. It was found that a large amount of diesel was lost into the unconverted oil due to poor fractionation efficiency in the main fractionators. To recover this lost diesel with an estimated value of 12 MM/year, a new stripper column will be installed. The stripper column will require stripping LP steam of 150t/day costing 1.0 MM per year. The cost for related piping would be estimated as part of HCU revamp project... 

The assessment first looked into the opportunities associated with design margin. By optimizing process conditions and pushing the equipment to the absolute limits, the plant could make majority of the spare capacity and push plant capacity by 10% with some minor modifications. However, beyond a 10% expansion, several major limitations were identified from detailed simulations, which included the feed heater flux limit before the main fractionator column, jet flooding limit in the main fractionation column, and reactor space velocity limit in the hydrocracking unit. 

In terms of throughput, the biggest unit in most plants is the crude distillation unit Figure 9). Many downstream conversion units also use distillation for production separation. For example, in a coker, hydrocracker, or FCC unit, an atmospheric tower, a vacuiun tower, and a multi-column gas plant may be required. 

The relative gain array for a refinery distillation column associated with a hydrocracker discussed by Nisenfeld and Schultz (1971) is given by... 

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