Decant oils

The principal sources of feedstocks in the United States are the decant oils from petroleum refining operations. These are clarified heavy distillates from the catalytic cracking of gas oils. About 95% of U.S. feedstock use is decant oil. Another source of feedstock is ethylene process tars obtained as the heavy byproducts from the production of ethylene by steam cracking of alkanes, naphthas, and gas oils. There is a wide use of these feedstocks in European production. European and Asian operations also use significant quantities of coal tars, creosote oils, and anthracene oils, the distillates from the high temperature coking of coal. European feedstock sources are 50% decant oils and 50% ethylene tars and creosote oils. 

Complex aromatic raw materials such as petroleum resids, decant oils, coal, and coal tars have been employed for many years by the earbon industry and eontinue to be used extensively in the fabneation of eoke, earbon, and artifieial graphite [1], These same feedstoeks also have the potential for use in produeing "advaneed" earbon produets such as carbonaceous mesophase, fibers, and beads 12-4],... 

Unlike coke produced from coal, petroleum cokes are derived from the residua of petroleum refining. Suitable feedstocks for good quality coke are thermal tars, catalytic cracker bottoms, and decant oils [17]. 

The liberated base is decanted, the alkaline aqueous solution is washed twice by 150 ml ether. After distillation of the ether, the previously decanted oil is added to the residue and distillation is effected in vacuo. THus, 135 grams of a colorless viscous oil, becoming carbonated in air, is obtained. BP(4 = 166°C, no = 1.5321, yield = 61%. 

The heaviest bottoms product from the main column is commonly called slurry or decant oil. (In this book, these terms are used interchangeably.) The decant oil is often used as a cutter stock with vacuum bottoms to make No. 6 fuel oil. High-quality decant oil (low sulfur, low metals, low ash) can be used for carbon black feedstocks. 

Products from the reactor are recovered in the main fractionator a J the gas plant. The main fractionator recovers the heaviest produc, such as light cycle and decanted oil, from the gasoline and ligh r products. The gas plant separates the main fractionator overhead vap< s into gasoline, Cj s, C4 s and fuel gas. The products contain sulfur compounds and need to be treated prior to being used. A combination of amine and caustic solutions are employed to sweeten these products... 

Adding residue to the feed increases the sulfur content of coke proportional to the incremental sulfur in the feed (Table 2-6). Thiophenic (ring-type) sulfur compounds crack more slowly, and the uncracked thiophenes end up in gasoline, light cycle oil, and decanted oil. 

Feed - (light cycle oil + heavy cycle oil + decanted oil) Feed... 

A test run is conducted to evaluate the performance of a 50,000 bpd (331 m /hr) FCC unit. The feed to the unit is gas oil from the vacuum unit. No recycle stream is processed however, the off-gas from the delayed coker is sent to the gas recovery section. Products from the unit are fuel gas, LPG, gasoline, LCO, and decanted oil (DO). Tables 5-2 and 5-3 contain stream flow rates, operating data, and laboratory analyses. The meter factors have been adjusted for actual operating conditions. 

Adjustment of the gasoline, LCO, and decanted oil yields to standard cut points. 

Conversion of ASTM Distillation to TBP Distillation for Gasoline, LCD, and Decanted Oil... 

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. 

Any mechanical revamp to improve the unit yields should always begin with installing an efficient feed and catalyst distribution system. This is the single most-important component of the FCC unit. An efficient feed and catalyst injection system maximizes gasoline yield and conversion at the expense of lower gas, coke, and decant oil and allows downstream technology to perform at its full potential. 

For nonhydrotreated feed, the gasoline sulfur level is about 10% of the feed sulfur level. For hydrotreated feed, it is about 5%. For example, if the sulfur content of a nonhydrotreated feed is 1.0 r (10,000 ppm), the sulfur in FCC gasoline will be 1,000 ppm. Assuming 80% desulfurization, feed to the FCC unit will contain 0.2% (2000 ppm) sulfur, resulting in FCC gasoline containing 100 ppm sulfur. Sulfur compounds that survive the hydrotreater are in the heav fraction and tend to end up in the LCO, decanted oil, and coke. 

Feed hydrotreating or hydrocracking reduces SOj, emissions and the sulfur content of FCC products. As discussed earlier in this chapter, many benefits are associated with FCC feed hydrotreating. It is important to note that most of the sulfur in a hydrotreated feed is in heavy organic compounds and will be concentrated in the decanted oil and coke. Consequently, for a given sulfur in the feed, more SO, will be produced with hydrotreated feed. 

Decanted Oil, Slurry, Clarified Oil, or Bottoms is the heaviest and often the lowest priced liquid product from a cat cracker. 

The separate stepwise condensation of the products from Fe-LTFT and Fe-HTFT synthesis produces streams of different carbon number distributions that serve as feeds to the oil refinery (Figure 18.4).30 It is consequently not necessary to employ an atmospheric distillation unit as the first step in the refinery. The stepwise condensation products from Fe-LTFT are reactor wax (liquid at LTFT conditions), hot condensate (>100°C), cold condensate (produced by condensation with the aqueous product and then phase separated), and tail gas (typically C4 and lighter). The stepwise condensation products from Fe-HTFT are decanted oil (liquid at 145°C 1.6 MPa), light oil (produced by condensation with the aqueous product and then phase separated), and tail gas. 

In the HTFT oil refinery the light oil and <345°C fraction of the decanted oil (obtained by passing the decanted oil through a vacuum flash drum) were clay treated. Clay treatment is similar to Bauxite treatment and is used to increase the octane number of the naphtha by acidic isomerization and to reduce the oxygenate content of the oil. Processing the LTFT and HTFT in separate (and different)... 

Oil and water are mixed together and then decanted. Oil flow rate is ratioed to water flow rate Ff. Interface is controlled by oil flow Fj, from the decanter with a proportional level controller. Water flow F ) from the decanter, which is liquid full, is on pressure control (PI). Steadystate flow rates are ... 

Fines removal from the slurry may allow it to be used for anode grade coke rather than fuel grade. Filters have been used successfully in this application and fresh feed or light cycle oil can be used to recycle the fines back to the riser instead of decant oil. 

Add a flash stage for the decant oil product to remove LCO for recovery... 

Add a slurry filter to remove fines and produce a high quality decant oil... 

FCC Residual Heavy Cycle Oil Slurry Oil Decant Oil Clarified Oil - This heavy... 

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