From Oil to Gold: Shinkai Unlocks Hidden Value in "Liquid Gold"

“Slurry Oil Withdrawal”- Metal Membrane Filtration System

Introduction

In the core process of oil refining, namely fluid catalytic cracking (FCC), heavy oil is cracked into high-value products such as gasoline and diesel under high temperature and with the aid of catalysts. However, this process generates some by-products. The heavy aromatics present in the slurry oil readily adsorb onto the catalyst surface and forms coke under condensation reactions. Such coke deposition deactivate the catalyst, which in turn impacts the conversion efficiency of fresh feedstock and the selectivity of the reactions.

The common way to maintain catalyst activity and ensure stable operation of the unit is to employ an operational strategy known as “slurry oil withdrawal.” This involves the controlled removal of a portion of the slurry oil, which is rich in polycyclic aromatic hydrocarbons (PAHs) and coke precursors, from the system to prevent its continued circulation and re-cracking. The withdrawn slurry oil is not a waste product but rather a potential high-value resource. Its primary components are unconverted hydrocarbons with boiling points above 350°C, which makes it an excellent raw material for producing high-value products such as carbon fiber, carbon black, and rubber softening agents. It is worthy of the name “liquid gold”.

The critical bottleneck in making full use of polycyclic aromatic hydrocarbons lies in removing the micron-sized catalyst powder mixed within them. Downstream high-value product applications have strict limits on impurity content in the feedstock. Therefore, implementing an efficient, economical, safe, reliable, and long-term operational filtration process for slurry oil withdrawal (separation of the solid catalyst particles from the heavy oil) is not only a prerequisite for developing high-added-value chemical and refining products but also a necessary step for enabling catalyst recycling, solving secondary pollution issues, and preventing coke formation within the units.

Challenges in Filtering Withdrawn Slurry Oil — A Multidimensional Technical Battle

Filtering withdrawn slurry oil is full of compounded and systematic challenges.

High Temperature and Pressure

The slurry oil discharged from the FCC unit typically reaches temperatures of 180–220°C or higher, accompanied by a certain pressure. Conventional filter materials would easily degrade or deform under such harsh conditions.

High Viscosity

The slurry oil’s high viscosity creates substantial fluid resistance. Driving this thick fluid through fine filter pores demands immense pressure and consumes excessive energy.

Prone to Clogging

The slurry oil contains high concentrations of catalyst powder (up to several grams per liter), with fine particles (typically 1–20μm) quickly forming a dense “filter cake” on the filter surface. This rapidly blocks the filtration channels.

Tendency for Coking

Large molecular aromatics, resins, and asphaltenes in the slurry oil readily undergo condensation reactions at high temperatures. This forms a stubborn, coke-like layer on the membrane surface and inner pore walls, which is extremely difficult to remove.

Traditional methods, such as sedimentation, centrifugation, or simple mesh filtration, struggle to address these issues due to their low separation accuracy, inability to operate continuously, and high energy demands, rendering them inadequate for modern industrial requirements.

Shinkai’s Filtration Solutions for Slurry Oil

We customize strategies for enterprises based on their specific needs to design specialized, efficient, and reliable filtration systems.

Key Technology No.1: Cross-Flow Filtration

The traditional method is dead-end filtration, where the fluid flows vertically to the filter screen, causing impurities to block the pathways.
Cross-flow filtration works in a different way. It allows the slurry oil to flow parallel at high speed across the membrane surface, thus generating a powerful tangential shear force. This force acts like an invisible brush and sweeps away catalyst particles attempting to deposit, while allowing only the clean oil molecules to permeate through the membrane.

Core Advantages: It significantly delays membrane fouling, thus enabling long-term, high-flux stable operation and creating possibilities for continuous filtration.

Key Technology No. 2: Metal Membrane

The metal membrane, usually made from stainless steel or alloy, works well with our advanced cross-flow filtration method with its superior performance.

Outstanding Separation Performance: Absolute interception and controllable accuracy.

The accuracy ranges from 0.1 to 10 μm, which ensures 100% interception and zero leakage.

Superior Physical and Chemical Resistance: No Worries About Extreme Working Conditions

It resists high temperature up to 900 ℃. With high strength-cartridge, it withstands pressure up to 50 bar, coupled with high resistance to erosion, solvent, acid and alkali.

Super long service life and Economical Efficiency

Thanks to the outstanding blowback performance, the service life of cartridges is extended to 10 years without frequent changes.

Prominent Safety and Environmental Benefits: Safe Materials and Green Production

It ensures 100% intention of solid particles with zero leakage and low safety and environmental risks.