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Petronor - Bilbao, Spain. 1997 FCC Turnaround

PhotoReport
The old disc [view a full-size image] 62Kb Jpg file
T-head disc slot welded plate [view a full-size image] 36Kb Jpg file
Old wear plate eroded and deflected [view a full-size image] 60Kb Jpg file
FEM analysis of the new internals [view a full-size image] 44Kb Jpg file
Old cone water cutting [view a full-size image] 58Kb Jpg file
Machining tool stand setting [view a full-size image] 73Kb Jpg file
New internals [view a full-size image] 55Kb Jpg file
New internals [view a full-size image] 50Kb Jpg file

PROBLEM: Modify, repair and retrofit a Ø103" flue gas double disc slide valve, cold wall design, manufactured by a Remosa competitor and in operation since 1983 at the Somorrostro refinery. This is a by-pass valve which is closed when the expander is in operation. In the event of an expander shut down, the valve is opened and gas is sent directly to the orifice chamber.

Old internal cone and wear plate after removal.

When the customer asked for Remosa intervention the valve was affected by excessive gas leakage in the fully closed position.

TECHNICAL DATA:

• body: SA 516 Gr 70
• discs: SA 240 Tp 304H
• guides: SA 240 Tp 304H
• stems: SA 182 F 304H
• cone: SA 240 Tp 304H
• refractory materials: RESCO RS 17 EC, RESCO RS 7, RESCO RS 3
• abrasion resistant material: RESCO AA 22
• process: Kellogg
• specification: Foster Wheeler Iberia.

  Design conditions:

  • pressure: 4.9 kg/cm²
  • temperature: 730 ^oC
  • flow rate: 250,000 kg/h

  Operating conditions:

  • pressure: 2.4 kg/cm²
  • temperature: 704 ^oC
  • flow rate: 230,000 kg/h

Leakage was estimated at 10 to 15% of the total flow loss of energy in the expander unit. The preliminary assessment, based on the analysis of the drawings was as follows:

• incorrect cone to internal parts joining
• lack of orifice plate support over the entire length of the guides
• disc thickness not sufficient to ensure 0.13 mm maximum deflection at mid span
• internal trim likely to deform
• excessive vertical clearances.

New wear plate machining.

SOLUTION: Remosa's proposal, based on the client's request for a gas leakage not exceeding 2%, was as follows:

1. cone modification
2. replacement of lower trim supporting part
3. construction of a new orifice plate capable of supporting the trim
4. change in internal arrangement to allow placing of a new orifice plate
5. construction of a thicker disc to keep deflection smaller than 0.13 mm
6. construction of new guides
7. reduction of vertical clearances through a fine machining of disc surfaces lined with Resco AA 22.

The work carried out in-house before the turnaround consisted of:

• design of the new internal parts at design temperature and pressure
• finite element analysis of internal parts
• construction of a new cone section
• design of a specific machine to allow planning and drilling inside the valve.

Immediately after the shut down, the following operations were carried out on site:

• cone cutting with a high pressure water cutter
• welding of a new cone section
• NDT
• installation of a specifically designed machine inside the valve body
• machining
• sand-blasting
• welding of anchors for abrasion resistant and refractory lining
• refractory application under Causeway supervision
• stuffing box and flange cover installation
• start-up.

The valve modification was completed in 18 days, working on two shifts of 10 hours each.

WHAT THE CUSTOMER HAD TO SAY. " ... [Remosa's] work left a strong impression of quality, later confirmed when measuring the final clearances at room temperature. All tasks were carried out meeting time schedules in a safe manner, complying with the quality standards set by Petronor and to full satisfaction of Petronor's personnel involved with this project. During the start up, the valve showed to work efficiently at operating temperature, fully meeting the gas leakage target set by Remosa. We certify the good work performed by Remosa and the excellent coopeation of their technicians who are held in high respect by Petronor."

Tests carried out by Petronor proved gas leakage to be less than 1%, far better than the original request.

Copyright © REMOSA spa 1998-2001 Last updated on April 27, 1999