Boiling bed residue hydrogenation technology under refining integration and refining structure transformation and upgrading

There are two main technical routes of heavy oil processing: decarbonization and hydrogenation. Decarbonization technology is represented by delayed coking and solvent deasphalting. Solvent deasphalting is difficult to be applied in large scale in existing oil refineries because of its high energy consumption and other shortcomings. Therefore, the primary choice of oil refinery is clean and environmental protection hydrogenation technology.

At present, the relatively mature residual oil hydrogenation technologies are mainly fixed bed, boiling bed and slurry bed hydrogenation processes. Compared with fixed-bed hydrogenation, the boiling bed process has significant advantages in the light residue. The catalyst can be replaced online, the utilization rate is high, the operation cycle of the device is long, and the operation is flexible. It can meet the requirements of the large size of the device and the long cycle operation, and it plays a pivotal role in the existing refining and chemical transformation process.

 

 

In the field of boiling bed hydrogenation technology, there are mainly H-Oil process and T-Star process of Axens Company in France, LC-Fining process of CLG Company in the United States and STRONG process with full independent property rights of Sinopec. 

Compared with foreign boiling bed hydrogenation technology, STRONG boiling bed has many characteristics and advantages. In terms of reactor, it creatively proposed gas-liquid-solid self-separation three-phase separator to replace high temperature and high pressure boiling pump, which greatly reduces the investment of the device and the safety of operation.  The microspherical catalyst has good fluidization effect and high impurity removal rate. 

 

At present, a lot of research work has been carried out in foreign countries on H-Oil and LC-Fining boiling bed hydrogenation technologies, mainly focusing on impurities removal rule under high residue conversion rate, long cycle operation of boiling bed device, etc., but few studies on the effective coupling of boiling bed hydrogenation technology and other technologies for different application scenarios. 

 

01. Technical Advantage

 

● Self-sustaining fluidized reactor

 

The internal flow of the STRONG fluidized bed reactor is enhanced by the internal components, so that the solid phase catalyst particles can directly reach the fluidization state under the action of the feedstock gas and liquid, so there is no need to use the harsh working conditions of the boiling pump.

STRONG reactor is mainly divided into reaction section and three-phase separation section.  The reaction section is a straight cylinder, and the three-phase separation section separates the gas phase and the solid phase through the action of the three-phase separator. The gas phase is discharged from the top gas phase outlet, and the solid flow flows back to the reaction section for circulation, while the liquid phase flows out from the side outlet.

 

Compared with the fluidized bed reactor promoted by boiling pump, the in situ self-supporting circulating fluidized bed reactor has a gas-liquid interface and a gas phase space at the top, but the catalyst is in a complete fluidized state, so there are catalysts in all the liquid phase reaction space, so the reactor is in a full catalytic hydrogenation reaction state, so the reaction efficiency and hydrogenation reaction product properties are better. 

 

● Function zone spherical catalyst

 

In foreign countries, strip catalyst (diameter 1.0 cm) is commonly used in boiling bed, while STRONG boiling bed hydrogenation catalyst is microspherical, particle diameter is 0.4~0.5mm.

Fine spherical particles are conducive to fluidization and high utilization rate.  The fine particles can also reduce the diffusion distance and improve the apparent activity of catalyst. In addition, the wear resistance of the spherical catalyst is obviously better than that of the strip catalyst, and the particle size distribution of the catalyst changes little during the operation cycle of the device. 

 

 

02. Application Scenario of Boiling Bed Hydrogenation Technology

 

● Produce clean oil products

 

Compared with the existing fixed bed hydrogenation and catalytic cracking combined process to produce clean oil, the boiling bed hydrogenation and catalytic cracking combined technology has significant advantages. Especially in terms of crude oil adaptability, it can process inferior raw materials (carbon residue is higher than 15%, metal mass fraction is higher than 120 μg/g) that are difficult to be treated by fixed bed residue hydrogenation.

After the residue passes through the boiling bed hydrogenation unit, the hydrogenated heavy oil is used as the feed of catalytic cracking to produce liquefied gas, gasoline, diesel oil and heavy oil. The heavy oil and oil slurry can be mixed with the residue into the boiling bed hydrogenation unit. 

 

● Production of chemical raw materials

 

Compared with other residuum processing methods, boiling bed hydrogenation has a higher residuum conversion rate, which can convert more heavy distillate into light paraffin oil, diesel oil and naphtha distillate. Then, flexible hydrocracking process is configured to further convert light distillate of wax oil and diesel oil into naphtha distillate suitable for generating olefin and other chemical raw materials, so as to realize efficient conversion of residue to chemical raw materials. 

 

● Production of low sulfur petroleum coke

 

At present, the outlet problem of high sulfur petroleum coke is a big problem faced by enterprises with delayed coking units. Improving the properties of coking raw materials is the key to remove high sulfur coke and produce high value low sulfur petroleum coke.

For the processing of high sulfur residue, boiling bed hydrogenation has a significant advantage. Through the high efficiency desulfurization of catalyst, the sulfur content in the unconverted oil of boiling bed is greatly reduced.  Unconverted oil is a high quality raw material for producing low sulfur petroleum coke. It can produce high value-added low sulfur petroleum coke with sulfur content less than 3.0%. 

 

● Production of low sulfur Marine fuel oil

 

Compared with the existing low sulfur Marine fuel oil using high cost low sulfur residue and other secondary processing distillate blending technology, and compared with the fixed bed residue hydrogenation to produce low sulfur Marine fuel oil, the boiling bed hydrogenation technology has significant advantages in the production of low sulfur Marine fuel oil.

Boiling bed hydrogenation technology can greatly reduce the production cost of Marine fuel oil by processing inferior raw materials.  In addition, the catalyst of boiling bed hydrogenation can be added online, and the operation cycle of the device can be greatly improved. 

 

● Processing unconventional oil products

 

Boiling bed hydrogenation also has a good application prospect in the processing of unconventional oil products such as coal tar, catalytic cracking diesel and gutter oil.

Coal tar and other high aromatics systems contain relatively high content of impurities and polycyclic aromatic hydrocarbons, and the heat release in the hydrogenation process is great. The conventional fixed bed reaction system is easy to produce hot spot and flying temperature problems, which affect the long cycle operation of the device.  Based on its full backmixing system, the fluidized bed has better mass and heat transfer effect, which can realize the stable operation of the device.