Process Technologies

Prime-D™ with cracking

While having to handle heavier diesel cuts, the refiner has to address the demand for more gasoline for the fuel market or for petrochemicals production downstream.

Consequently, the middle distillates hydrotreatment target is evolving to bring sufficient flexibility to the products properties as well as yields adjustment. To this end, deep optimization of cracking and hydrotreatment catalyst systems are required.

Prime-D™ with cracking is the optimal solution when deep hydrogenation is not enough to reach stringent specifications on density and/or cetane for refractory feedstocks, or when additional gasoline production is desired.

Prime-D™ with dewaxing

In addition to reaching ultra-low sulfur content, cold flow properties and specifications of the diesel product may have to be improved due to local climatic constraints.

Prime-D™ with dewaxing is a competitive alternative for cold flow properties improvement as compared to more costly options such as feed undercutting, kerosene blending, or chemical additive addition, leading to high operating costs and loss in diesel yield.

Conventional Prime-D™

Conventional Prime-D™ ensures achievement of ultra-low sulfur diesel (ULSD) specification, density and cetane improvement over a large range of diesels cuts: from straight run to large cracked feedstocks.

Prime-K™

In case sulfur content of kerosene feed is above 0.3%wt, and/or smoke point and/or freezing point of kerosene has to be improved to meet jet A1 specification, or even if flexibility is envisioned to send kerosene to diesel pool at 10ppm of sulfur content, Sweetening process is no more the solution, but Prime-K™ is.

The objective of the Prime-K™ process is mainly to reduce the total sulfur content of the kerosene cut and, if necessary, the aromatics content in order to improve the product smoke point, to produce jet fuels.

Sweetn’K™

Sweetn'K™ converts Mercaptans directly to RSSR and is used to treat Kerosene through a catalyst fixed bed of SCPS-ready allowing to comply with JET-A1 specification. The unit is made of 3 sections:

• A front prewash section, which neutralizes aliphatic acids.
• The reaction section where an oxidation reaction converts mercaptans into disulfides. The reaction between mercaptans and air occurs in an alkaline environment in contact with Axens Solutions catalyst “SCPS Ready”.
• In the finishing section, the kerosene is dried by a water removal mass and finally upgraded on a clay bed to improve product color.

This process features mild operating conditions:

• Low pressure
• Ambient temperature

Hexorb™

Ultimately, to go beyond the 90 RON threshold, substantial conversion of the methyl pentanes is required. This can be achieved with full conversion of normal paraffins by integrating the Hexorb™ separation process with the reaction section. This process combines a cyclic molecular sieve adsorption system with a downstream de-isohexanizer that splits raw isomerate from the molecular sieve section into an isomerate overhead stream rich in isopentane and dimethylbutanes and poor in the lower octane methylpentanes (MPs) from two streams containing heavier components.

Ipsorb™

The Ipsorb™ scheme is shown to recycle the normal paraffins for their complete conversion.

This process uses a deisopentanizer (DIP) to separate the isopentane from the reactor feed. A small amount of hydrogen (H2) is also added to the reactor feed. The isomerization reaction proceeds at moderate temperature, producing an equilibrium mixture of normal isoparaffins. The catalyst has a long service life. The reactor products are separated into isomerate product and normal paraffins in the Ipsorb™ molecular sieve separaction section, which features a novel vapor phase PSA technique. This enables the product to consist entirely of branched isomers.

De-pentanizer (DP)

To reach a higher RON, a Depentanizer can be implemented between the Stabilizer and the DIH, allowing to recycle the unconverted nC₅ back to the DIP. This overall improvement of the C₅ conversion leads to an increase of the isomerate RON.

Isomerization with De-isohexanizer (DIH)

For still higher RON isomerate, a deisohexanizer can be added downstream from the reaction section. The higher octane and more volatile iso-hexanes (dimethylbutanes) are removed by distillation together with the C₅’s. The distillate is combined with the de-isohexanizer bottom to become the final isomerate product. A side-stream from the bottom half of the column, concentrated in lower octane species such as methylpentanes (MPs) and the unconverted n-hexane, is recycled to the reactor.

De-isopentanizer (DIP)

To improve the octane boosting effect of the isomerization process, a deisopentanizer column can be integrated upstream of the isomerization unit. The advantages of this scheme are the following:

• having a new separate base with a high MON to be blended into the gasoline pool: isopentane
• sending a low isopentane-containing feed to the isomerization unit, so that the net isopentane production is larger

A further step to increase the octane pool is to split the reformate into two cuts. A light reformate is thus obtained including C₅ and C₆ components. This cut can be isomerized after separating the isopentane. This can be achieved by blending the light reformate with the straight run light naphtha and processing them simultaneously.