Precision Slag Discharge Filter Renovation Project for Catalytic Cracking Unit in Chinese Mainland

Project Background & Pain Points

Feed oil of a large refining catalytic cracking unit contains fine catalyst powder and colloidal impurities. The original bag filter without automatic slag discharge structure clogs frequently, requiring shutdown for manual bag disassembly and slag removal every 72 hours for 4 hours each time. The unit runs under reduced load with huge annual output losses. Manual bag replacement brings heavy labor intensity; 2 maintenance staff work round-the-clock with annual filter bag procurement cost over 180,000 RMB. Accumulated impurities block heat exchange tubes, lowering heating furnace efficiency and raising fuel consumption by 8%.Without automatic differential pressure early warning, sudden complete blockage easily causes pipeline overpressure and leakage risks. The client requires fully automatic closed slag discharge, online filtration without shutdown, and reduced labor & consumable costs.

Customized LEFILTER Solution

Aiming at high-solid feed oil working condition, 4 sets of LF-PZ precision slag discharge filters are installed in parallel. The whole machine adopts 316L stainless steel pressure-resistant cylinder for high-temperature oil service. Internal three-stage gradient screens: 80-mesh coarse filter intercepts large particles, 200-mesh sintered metal precision layer captures micron catalyst powder, with built-in 360° rotary scraper self-cleaning mechanism.When differential pressure hits 0.13MPa, scrapers automatically remove filter cakes, and the bottom pneumatic closed slag valve opens synchronously to finish slag discharge within 30 seconds without cutting off oil feed to guarantee continuous unit operation. Equipped with explosion-proof electric control cabinet to collect inlet & outlet differential pressure and slag discharge frequency, data uploaded to plant central control for remote adjustment of slag discharge pressure threshold. Modular flanges realize in-situ replacement of old filters without pipeline modification, with full equipment delivered within 9 days.

Differentiated Core Advantages

1. Linked built-in scraper & pneumatic bottom valve for fully closed slag discharge without leakage to avoid oil volatile pollution;

2. Online slag discharge without feed shutdown completely eliminates output loss from load-reduction cleaning;

3. Reusable metal screens remove frequent bag replacement, cutting annual consumable cost by 90%;

4. Differential pressure automatic slag discharge removes manual inspection & cleaning, lowering labor demand by 80%;

5. Pressure & corrosion resistant cylinder adapts to high-temperature refining oil with service life over 10 years.

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Operating Effects & Client Benefits

Stable operation for 13 months with 96% interception rate of solid particles in feed oil. Rear heat exchanger blockage frequency drops by 94%, heating furnace fuel consumption reduces by 7%, saving 720,000 RMB fuel cost per year.Automatic slag discharge cuts maintenance staff from 2 to 1, saving 240,000 RMB labor cost annually; no filter bag replacement saves 160,000 RMB yearly on filter materials. This precision slag discharge filter solves three major pain points: frequent shutdown, high consumable expense and heavy manual workload, acting as a demonstration renovation project for catalytic unit filtration.