ALTERNATIVES OPERATIONS

2.3.1. Steam stripped kerosene operation

Normally the Kerosene stripper, T-1102, is operated with the reboiler E-1110. However, it may be necessary to take E-1110 out of service while the unit is on stream. Low pressure steam is provided as an alternative stripping medium to permit continued operation of the stripper with E-1110 out of service. Under these conditions the kerosene product will be routed to crude recirculation header.

To take E-1110 out or service, please refer to section 7.6 2.3.2. One Desalter operation

Normal operation is to process the crude oil feed through both desalters in series to minimise the amount of salt carried forward to the hot downstream heat exchangers, furnace and the downstream equipment, and to meet the sodium specification in the RFCC feed. Wash water normally flows counter current to the oil through both desalters in series, before being routed to the refinery Effluent Treatment Plant.

The desalters are designed for on-line desludging. However, it may become necessary for operational and / or maintenance reasons to shutdown one or other of the desalters. Both the oil and the wash water pipework are configured so that either desalter may be operated on its own while the other can be drained, valve isolated and blinded.

Refer to Normal Shutdown section 7.7 for desalter isolation procedure.

2.3.3. LGO dryer bypass

It could be necessary to isolate the LGO drier for maintenance or other causes. The actions needed to isolate this item are the following:

• Turn to minimum LGO flexibility case

• Ensure line LGO-110227 is empty by opening the drain of this line.

• Close the drain and change the spectacle blind position in line LGO-110227.

• Close the locked open valve on line LGO-110224 in order to stop the vacuum on the drier.

• Open drier bypass line (110227) by opening first the valve close to the line LGO-110216 and next, the valve close to the line LGO-110218.

• Switch the 011-UX-012 initiator from 011-LXA-020 to 011-LXA-080, in order to ensure the pump stops with a low low level trip in T-1103.

• Set the LIC-019 controller to manual and output zero.

• Close the T-1105 outlet by closing the valve on line LGO-110218.

• Sent LGO product to storage tank TK-5115. This tank has a capacity of 4 days of production without sending to the blending. Wet diesel is not really a problem because free water will be decanted in the storage plants of blended products.

• Drain the remaining hydrocarbon in the column by line CD-118548.

• Blind the drier from all process lines.

• Ensure vent is open, and steam out routing oily condensate to the closed drain.

• Continue steaming, checking drier atmosphere regularly for hydrocarbons.

• When checks are satisfactory, stop steaming, open manways, allow vessel to cool, recheck atmosphere for oxygen and hydrocarbon and hand over to maintenance.

2.3.4. HGO dryer bypass

The procedure is similar to the described in 2.3.3:

• Turn to maximum LGO flexibility case.

• Ensure line HGO-110191 is empty by opening the drain of this line.

• Close the drain and change the spectacle blind position in line HGO-110191.

• Close the locked open valve on line HGO-110195 in order to stop the vacuum on the drier.

• Open drier bypass line (HGO-110191) by opening first the gate valve close to the line HGO-110182 and next, the valve close to the line HGO-110186.

• Switch the 011-UX-010 initiator from 011-LXA-023 to 011-LXA-081, in order to ensure the pump stops with a low low level trip in T-1104.

• Set the LIC-022 controller to manual and output zero.

• Close the T-1106 outlet by closing the valve on line HGO-110186.

• Sent HGO product to storage tank TK-5109. This tank has a capacity of 4 days of production without sending to the blending. Wet diesel is not really a problem because free water will be decanted in the storage plants of blended products.

• Drain the remaining hydrocarbon in the column by line CD-118543.

• Blind the drier from all process lines.

• Ensure vent is open, and steam out routing oily condensate to the closed drain.

• Continue steaming, checking drier atmosphere regularly for hydrocarbons.

• When checks are satisfactory, stop steaming, open manways, allow vessel to cool, recheck atmosphere for oxygen and hydrocarbon and hand over to maintenance.

2.3.5. E-1102 and E-1104 isolation.

It could be necessary to clean E-1102 and E-1104 while unit remains online. The actions required to be done are as follows:

• Put the unit at turndown (50% of normal flow rate).

• Stop Pumparound pump P-1102 A/B. Top pumparound duty is capable of handle the excess of duty due to the fact that unit is at turndown.

• Isolate E-1102 by gate valve placed at lines K-110257 and K-110258.

• Open E-1104 HGO bypass line (HGO-110185).

• Close HGO circulation through E-1104 by gate valves placed on lines HGO-110181 and HGO-110198.

• Reduce then crude circulation to both heat exchangers by closing control valve 011-TV-007B.

• Isolate crude charge of both heat exchangers.

• Drain both sides of the Heat Exchangers and to Close Drain.

• Blind the heat exchangers.

• Ensure vent is open, and steam out routing oily condensate to the closed drain.

• Continue steaming, checking drier atmosphere regularly for hydrocarbons.

• When checks are satisfactory, stop steaming, allow heat exchanger to cool, recheck atmosphere for oxygen and hydrocarbon and hand over to maintenance.