PTQ Q2 2023 Issue

Vacuum distillation

Hydrotreating unit

Hydrocracking unit

Hydroisomerisation (HIDW)

Hydronishing

Lube oil +waxes

Dewaxed oil

Atmospheric residue

Vacuum distillates

Base lubricant

Vacuum residue

Deasphalted oil

Propane deasphalting

Light/middle distillates

Asphalt

Figure 4 Processing scheme for base lubricating oil production through the hydrorefining route

refinery competitiveness relying exclusively on the solvent route is that the Group I and II lubricants have lost market share over the past years. This is mainly related to the tech - nology requirements of the newest automotive engines. Figure 3 forecasts the evolution of market share for the dif - ferent base oils. According to the data from Figure 3 , a significant reduc - tion in the demand for Group I base oils is projected, leading to a significant competitive loss for refiners relying on base oil production exclusively through solvent routes. Hydrorefining route In lubricating oil production by hydrorefining, physical pro - cesses are substituted by catalytic processes, basically hydroprocessing processes. Figure 4 shows a block dia - gram of the processing sequence to produce base lube oils through the hydrorefining route. In this case, fractionation in the vacuum distillation step has more flexibility than in the solvent route. Once the streams are cracked in the hydrocracking unit, another dis - tillation step is necessary. After the vacuum distillation and propane deasphalting steps, the process streams are sent to a hydrotreating unit. This step seeks to saturate polyaromatic compounds and remove contaminants, including sulphur and mainly nitro - gen, which is a strong deactivation agent for the hydro - cracking catalyst. In the hydrocracking step, the feed stream is cracked under controlled conditions, and chemical reactions like dehydro - cyclisation and aromatics saturation occur, which gives the process stream adequate lubricants characteristics. The following hydroisomerisation step seeks to promote the isomerisation of linear paraffins, which can reduce the viscosity index, producing branched paraffins. After hydroi - somerisation, the process stream is pumped to hydrofinish - ing units to saturate the remaining polyaromatic compounds and remove heteroatoms. In the hydrofinishing step, the water content in the lube oil is controlled to avoid turbidity in the final product. In comparing the lubricant production routes, it can be observed that the hydrorefining route gives more flexibility in relation to the petroleum to be processed. As mentioned earlier, as the solvent route basically applies to physical processes, it is necessary to select crude oils with higher paraffin content and low contaminants (mainly nitrogen) for processing. Another solvent route disadvantage is that the applied solvents can cause environmental damage and need special security requirements during processing.

Production of low-value-added streams like aromatic extraction is another disadvantage. It should be noted that an advantage of the solvent route over the hydrorefining route is that it can lower capital investment while producing paraffins that can be directed to the consumer market. Brazilian lubricating market The Brazilian domestic market of paraffinic oils is supplied by refineries that apply the solvent route with a hydrofinishing step to produce lubricating oils and waxes for a variety of consumers like food and cosmetic industries, among others. The national lubricating production in 2019 was 3.5 million barrels. Additionally, the internal market is supplied by some importers; according to Brazilian Petroleum Agency (ANP) data, the internal consumption of lubricating reached 7.7 million barrels in 2019. In the Brazilian case, a significant part of the market is sup - plied to recycled lubricating oil. The recycling or re-refining of used lubricating oil fulfils a double role: it eliminates a hazardous residue, and it reduces the need to extract higher quantities of petroleum to produce base lubricating oils. The first industrial process developed to recover the used lubricating oil is called the acid-clay process, or Meiken pro - cess. A basic process flow diagram for the Meiken process is shown in Figure 5 . Due to this simplicity, the acid-clay process needs relatively low capital investment. However, due to the high quantities

Water

Used lubricating oil

Thermal treatment

Grating

Decanter

Dehydration

Sulphuric acid

Activated clay

Decanter

Clarication

Acid sludge

Sulphonation reactor

Diesel oil

Distillation

Used for clay recovery

Distillation

Spindle oil

Base oil

Filtration

Figure 5 Basic process flow diagram for acid-clay process

PTQ Q2 2023