Antecedentes del problema

15.1.1 Design operating conditions

15.1.2 Guidelines for operation of the reactor section 15.1.3 Feed quality and poison

15.1.4 Cause and effect table 15.1.5 Troubleshooting 15.2 DEBUTANIZER SECTION

15.3 OFF-SPEC IFICATION PRODUCTS HANDLING 15.3.1 LPG

15.3.2 Platformate

15.3.3 Off-specification handling table

15.4 TYPICAL EXAMPLE FOR COLLECTING DATA & QUALITY CONTROL

1. SUMMARY OF START-UP

On the following pages, a logic diagram is presented to summarize the different steps of an initial start-up of the Platforming Unit, as well as a table showing the expected start-up schedule.

Purge the NHDT Stripper (T-1201) and the Platforming Debutanizer (T-1301)

Establish Naphtha Circulation Between NHDT and Platforming Start Stripper T-1201 and Debutanizer T-1301

Purge the Reaction and the RECOVERY PLUS system

Hydrogen Pressure the Reactor and the RECOVERY PLUS system

Start Chloride Adjustment Program

Feed Introduction to the Reactors and then to the Debutanizer

Establish Normal Operating Conditions Hydrogen Circulation and Reactor Warmup

2. PRESTART UP PRECAUTIONS

This section describes the startup of the Platforming unit on a fresh load of catalyst. As a CCR unit is attached, refer to it's manual for precommissioning and startup details.

However, in this situation the only section of the CCR that must be functional during the Platforming Unit startup is the Lock Hopper No. 2 system. It is needed to reinventory the reduction zone above reactor No. 1. During startup thermal and mechanical effects in the stacked reactors will result in a loss of catalyst from the reduction zone and possibly reactor No. 1. If it is not replaced via Lock Hopper No. 2 the catalyst seal in reactor No. 1 could be lost. Variations in the startup procedure described are possible on subsequent startups, depending upon how complete a shutdown has previously been made.

NOTE: During the start-up of the unit, particular care should be taken not to exceed equipment limitations.

Prior to startup, the Platforming reactor section should be dry to minimize leeching of chlorides from the catalyst during the startup sequence. Any water which has collected in the system during the shutdown should be drained. The wet areas of the unit should be blown dry if possible. For the initial unit startup the unit should have been dried out before the catalyst is loaded for those cases where the unit has been shutdown for catalyst change-out and equipment has been filled with water for testing, circulation of hot gas through the reactor section prior to catalyst loading is also advisable. A dryout procedure will ensure a dry plant for catalyst loading.

Oil or flammable gas should never be charged into process lines or vessels indiscriminately. If the lines or vessels have contained air, suitable purging should be done.

Similarly, air should not be allowed to enter lines or vessels which have contained hydrocarbon until proper safety precautions have been taken. At no time should wet air (ambient or plant air) or refinery fuel gas be purged through the catalyst bed. The moisture in the air and fuel gas will leech the chloride off the catalyst as was mentioned earlier.

Also, the fuel gas could contain other catalyst poisons such as sulfur. The following procedure for purging and preparing the unit for startup should be closely followed. If varying the purge procedure appears necessary, the unit supervisor’s approval should always be obtained.

Hydrotreated naphtha should be available for the unit startup. Hydrogen available in the naphtha hydrotreater unit can be placed on-line before the Platforming Unit. Otherwise, previously treated naphtha taken from storage can be used. Typically, such feed will have the following contaminant levels:

Boiling Range As per design Total Sulfur 0.5 wt-ppm Total Nitrogen 0.5 wt-ppm

Chlorides *(0.5 wt-ppm)

Lead *(20 wt-ppb)

Arsenic *(1 wt-ppb)

Water + Dissolved Oxygen + Combined Oxygen = Low enough to produce less than 5 mole ppm water in the recycle gas with no water injection.

* as low as the analytical method used for analysis is capable of detecting; parenthetical values are current UOP laboratory method limits.

For the first start-up of the CCR Unit, when hydrotreated feed is not available, startup may be done on non-hydrotreated straight run naphtha providing it meets the following limitations:

Total Sulfur 100 wt. ppm maximum Total Nitrogen 1 wt. ppm maximum.

Arsenic 5 wt. ppb maximum

Lead 25 wt. ppb maximum

Halides 1 wt. ppm maximum

End Point 204°C maximum

Bromine N° 1 maximum

The startup operating period on this feedstock must be limited to a maximum of twelve hours and all reactor inlet temperatures must be maintained below 482°C during this period.

NOTE: Regardless of whether previously hydrotreated or untreated straight run naphtha is used for the Platforming unit startup, the feed must be routed through a stripping column for adequate stripping and drying prior to being charged to the Platforming unit.

3. PREPARE UNIT FOR CHARGING

a. Check that all blinds have been removed and that all safety valves are installed.

b. Check that all utilities are available where required.

c. All instruments should be ready for service.

d. Leak check all sections of the unit including Lock Hopper No. 2 system. Slowly pressure to 7 barg with either nitrogen or air (instrument air in the reactor section).

Check for leaks at all flanges, valves and fittings as required. Also monitor the individual section pressures. If no leaks are found and system pressure holds for one hour with no more than 0.15 bar loss, then the leak test has been successful. The pumps and compressors should be isolated from the rest of the unit during the leak test. They can be leak checked separately.

4. PURGE AND START THE NHT STRIPPER (T-1201), SPLITTER (T-1202), AND PLATFORMING FRACTIONATION SECTION

a. Purge the towers (NHT Stripper T-1201, Splitter T-1202, and Platforming Debutanizer T-1301) with nitrogen until oxygen-free (less than 0.3% oxygen)

Introduce the nitrogen at low points. The towers should be purged from connections at the base and vented at the highest point. All reflux and charge lines should also be purged as well by using connections on the reflux and charge pump piping for introduction of the gas. Continue purging until the vent gases escaping through the vents on top of the tower and on the overhead receiver are oxygen free. Also be sure all dead legs have been properly purged.

b. Prior to fractionation section startup, establish column pressures at design operating pressure. or maximum sweet fuel gas header pressure (3.3 barg), whichever is less.

c. Line up startup naphtha to the NHT stripper tower 1201 and then to the Splitter T-1202.

d. Bypass the Platforming reactor section by closing the block valves on the charge line from the stripper bottoms product line to the Platforming combined feed exchanger E-1301 (the startup by pass line tie-in is located between the flow control valve 013-FV-003 and the Combined Feed Exchanger Filters ). Do not flush hydrocarbons into the Platforming reactor section

The startup naphtha is now lined up to the NHT stripper T-1201 and then onto the Platforming Unit Debutanizer Feed-Bottoms Exchanger E-1306, bypassing the NHT and Platforming reactor sections.

e. Start a flow of startup naphtha to the fractionation section of the NHT through the normal charge lines using the reactor section bypass lines. Start a flow of startup naphtha to the platformer Debutanizer (T-1301) through the Platforming reactor section bypass line (taken downstream valve 013-FV-003).

f. When a good working level has been established in the Stripper T-1201 bottoms (012-LIC-020), start heatup of that column (using reboiler H-1202). Continue in similar fashion on other columns in the fractionation section.

NOTE: If there is any chance that water is in the towers, heatup very slowly. If water vaporizes too quickly the pressure surge could damage the trays

g. Continue the startup naphtha flow until an adequate inventory has been established in all towers T-1201, T-1202, T-1301 then discontinue flow.

h. Establish reflux on each column when adequate overhead receiver (respectively V-D-1209, D-1210, D-1303) levels appear. Raise or lower column heat inputs, as necessary, to maintain reasonable reflux to feed ratios. It might be necessary to operate the towers at less than design pressure in order to establish reflux.

i. Establish circulation between columns of the NHDT Unit and the Platforming Debutanizer and establish such circulation at approximately 50% of normal rate. In this case, the reaction sections of the two units are bypassed and the Debutanizer bottoms material is returned to the Feed Surge Drum D-1201 of the NHDT Unit, using the startup by pass line located downstream of exchanger E-1305 A/B.

The startup loop is as follows :

D-1201 T-1201 T-1202 T1301

NHT Feed Surge Drum Stripper Naphtha Splitter Debutanizer

j. Drain water from overhead receivers and system low points, as necessary.

k. Rotate pumps and commission instruments to test as much equipment as possible before cutting charge into the Platforming reactors.