8. INTERMEDIATE TRAY INSTALLATION SEQUENCE | Tower Internals in Plants & Refinery
a. Prerequisite
✓ Below bed is loaded.
✓ The adequate dump-nozzle is open and air circulation is in service.
✓ Panels of the tray have been prepared at ground as per procedure.
✓ Atmosphere inside the adsorber is breathable (no apparent dust).
✓ Support rings and top faces of beams are clean ( of any sieve particles or any other material).
b. Intermediate tray panels installation
✓ Install the working boards on the beams.
✓ Install the panels following the panels installation procedure using spacers and screw clamps as described for Lower Tray.
✓ During panels installation, avoid any sieve surface disturbance, and ensure there is no foreign material falling into the sieve bed.
✓ Tightness procedure for intermediate tray
• Check the horizontality and the flatness of the tray.
• Check the good contact between panel frame and beams. Use shims of different thickness if required.
• Install alternate rows of glass fiber rope and pack them following AXENS recommendations.
• Proceed to the setting up and the welding of the numerous clips on the panels frames.
✓ Tack weld all potential moving part as: bolts, shims plates …
Figure 32: Intermediate trays panels installation sequence.
✓ On each Intermediate Tray a blanket is installed using a wire rope welded on the center pipe and angle bars welded on the four panels surrounding the center pipe. Refer to Adsorbent Tower data sheet DWG E/13, for further details regarding this item.
✓ Tack weld all potential moving part as: bolts, shims plates …
Figure 33: Center Pipe Tightness Blanket.
It is to be pointed out that some steps of the installation of this item have to be done during tray panels inspection and preparation at ground, in particular angle plate welding.
c. Piping installation
i. Prerequisite
✓ Prepare at ground internal pipes and gaskets.
✓ Check piping portions are properly punch-marked according to punch marking philosophy.
✓ Check visually the welding inside the piping (restrictions, barbs … which to be avoided). Clean or correct if necessary.
✓ All flexible hoses have been inspected (Temporary protection to be removed, then reinstalled until final installation).
✓ The relevant bed walls have been cleaned using vacuum cleaner to remove the sieve dust prior to open the relevant shell nozzles located on the relevant annular chambers.
✓ All piping shall be blown with air on the top platform in order to remove all foreign materials and dust which might be accumulated inside and outside. If any corrosion or rust is detected during piping unpacking, then it shall be completely removed at ground location, prior to temporary store the internal in its relevant containers.
ii. Leak test
In case of elbows visual inspection is not satisfactory, a piping leak test procedure is issued by AXENS.
✓ The leak test of the piping will be done outside the adsorbers,
✓ The leak test duration will be 10 minutes for each piping and no leaks are allowed.
✓ The pressure test will be 0.5 bar g of instrument air, for both injection and withdrawal piping, ✓ AXENS will be mandatorily witnessing the test.
✓ The whole piping including the flexible hoses is completely dried out using IA, prior its final installation after the leak test is completed.
✓ Any damaged flexible hose is rejected and replaced by a brand new one, to be tested as well.
iii. Installation
✓ Remove blinds from the nozzles of the annular collector and plastic plugs on the tray panel.
✓ AXENS advisor check annular chamber and panel flange status.
✓ Connect flange of the piping to the annular chamber. Introduce gasket (in accordance with process specification). and tighten the annular chamber flanges. The other flange of the piping is kept free and is set to the tray’s flange with a protective sheet.
Figure 34: First step for internal piping installation.
• Operation under AXENS supervision: Thank to hose compression device, position of the horizontal flange is adjusted to fit with the corresponding flange on the tray panel.
Figure 35: Second step for internal piping installation.
✓ Check the gaskets (in accordance with process specification).
✓ Install the gasket and bolt the flange to the collector nozzle.
✓ Wait for piping supplier or AXENS inspection, (This could be done quadrant by quadrant to avoid losing time waiting for inspection and the green light to go ahead).
✓ Repeat operation to the next tray panel nozzle.
Attention: Horizontal part of the piping includes flexible hoses which are fragile. They are protected until piping installation by special sheet cover that must be removed at the very last moment. Afterwards special care should be taken to avoid any damaging of these items.
iv. Final bolting
✓ Before final bolting, the annular chamber nozzles and inside of the chambers are once again cleaned using special device and vacuum cleaner. This is done bed by bed.
✓ Special attention to be paid to avoid any gasket damaging during this phase.
v. Final inspection
✓ Final inspection of the piping and stress in flexible hoses is done at the same time as the final inspection of the tray, and just prior to start loading. This final inspection is made by AXENS, whatever inspection the client will want to perform. The go ahead for loading approval is only given by AXENS dedicated representative after the completion of a satisfactory final inspection.
✓ All necessary measurements are taken by AXENS during this final inspection.
d. Beams installation (All levels except beams of upper tray)
The following guidelines are available for all levels except for beams corresponding to Upper tray.
For Upper tray beams installation, refer to next paragraph
✓ Install the beams as per beams installation procedure.
✓ Punch mark each beam once the complete set is installed.
Figure 34: Intermediate trays beams installation sequence.
Attention: Be careful not to damage the internal piping especially the flexible hoses, during beams handling and installation.
e. Upper tray beams installation
✓ Prepare at ground the beams of the tray.
✓ Install the beams beginning by the 4 beams located on the diameter.
✓ Check for the relative elevation between beams and annular ring and use shim plates if necessary to achieve satisfactory levelling.
✓ Check for the perpendicularity of these 4 beams two by two by measuring the hypotenuse of two virtual triangular shapes in the adsorber for each pair of beams.
Figure 35: Checking of perpendicularity between beams.
✓ For each set of 2 perpendicular beams, check for the relative position of the tap holes on each beam in order to make sure the notches on panel located close to the center pipe will allow bolting.
Figure 36: Cehcking of relative location of threaded holes.
✓ Once the perpendicularity of the 4 beams located on the diameter and adequate relative position of tap holes is achieved, lock the beams in position with shim plates between the beam and the beam support and install bolts.
✓ Check once again the perpendicularity of the 4 main beams and tack weld shim plates and nuts.
✓ Then continue installation as per the following beams installation sequence.
Figure 3 7: Upper tray beams installation sequence.
✓ For each beam :
(1) Adjust the levelling of the beams usmg the various thickness shims.
(2) Adjust the relative position between beams :
• check for the perpendicularity with the main beam
• Adjust the relative position of tap holes with the gap between main beam
• and the parallelism with the secondary beam which is set on the diameter
✓ Bolt the beams to the different supports.
✓ Check the fastening, the horizontality, the relative position (perpendicularity and parallelism) and the flatness of the beams.
✓ Tack weld all potential moving parts: bolts, shim plates …
✓ Punch mark the beams once the complete set is in position.
Remark : Upper trays panels will be fastened to the beams.
✓ The positioning of beams should be done perfectly in order to avoid unloading the top bed if panels bolting notches do not match with beams tap holes.
f. Thermocouples installation
- Flexible thermocouples will be installed prior to loading of the relevant bed (for beds 11, 6 and 1 only of each adsorbent tower). This operation is done in accordance with thermocouples manufacturer recommendations. Typical steps for thermocouples installation.
- Tack weld the support clips on the beams.
- Introduce the set of thermocouples through the thermowell and tight the flange. (check the gasket before installation)
- Unwrap the set of thermocouples and develop them along the beams.
Remarks: Flexible thermocouples have different length depending on the position of the measurement points. - Be sure that the right thermocouples are on the right position before fixing. Fasten the flexible thermocouple with the support clips.
- Bend the thermocouple at its end, in accordance with the right position described in the PROCESS DA TA BOOK. Minimum bending radius of thermocouples: 100 mm.
- Pack glass fiber rope inside the nozzle and around the thermocouples to avoid dead volume, as necessary.
Figure 38: Thermocouples nozzles packing.
(AXENS to supply in due time detailed procedure for flexible thermocouples installation)
g. Sample point connexions
Sample points to be installed prior to loading the relevant bed (for beds 1 of each adsorber).
Installation requires fiber rope to be packed inside the nozzle and around the sample devices to avoid dead volume, if necessary.
Figure 39: Sample points nozzles packing.
h. Tray inspection
✓ Clear out the tray.
✓ Check thermocouples are in place.
✓ Check all gaskets are in place and check the good tightening of flanges.
✓ Check the integrity of the flexible hoses for which protective shell had been removed for installation.
✓ Dismount the bottom part of the center pipe ladder.
✓ Remove neoprene sheets from the panels.
Clean perfectly the panel screen with vacuum cleaner.
✓ Inspect carefully the screen. Use feeler gauges when visual inspection is questionable.
Refer to appendix B for main AXENS inspection check points regarding lower tray. Final inspection will be performed as per AXENS check-list (issued by AXENS Start Up manager).
i. Sieve loading
i. Next intermediate trays
✓ Repeat operations described in previous chapter.
✓ Continue sieve loading of bed I until the sieve reaches the top level of next tray beams.
Regarding beams and panels arrangement, trays are alternatively odd and even from the bottom to the top intermediate trays.
✓ Following the progress of the loading, fresh air intakes are to move up.
Remark: Upper tray beam arrangement and installation sequence is the same as for bottom tray. Refer to the relevant section of these recommendations for further details.