ISSUED FOR INFORMATION
0 ISSUED FOR INFORMATION JQR JLM DBA May 8, 2019
BPP18-0009: EPC of New LPG and Propylene Spheres Piping, Electrical & Instrumentation
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond
0
C-LPGP-PP-001
BRXX-X-XX01 Sheet No. 1 of 8
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.2 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
TABLE OF CONTENTS
Executive Summary ........................................................................................................................3
1. Introduction ................................................................................................................................4
2. Objective ......................................................................................................................................4
3. Scope ............................................................................................................................................4
4. Acronym ......................................................................................................................................4
5. System Description .....................................................................................................................4
6. Remote Retention Pond Sizing Guidelines ................................................................................5
7. Remote Retention Pond Size Evaluation ...................................................................................5
8. Conclusion and Recommendations............................................................................................7
9. References ...................................................................................................................................7
10. Attachment ................................................................................................................................8
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.3 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
Executive Summary
The New LPG Sphere, S-1129, and New Propylene Sphere, S-1135, will provide PBR with the
necessary product storage for LPG and Propylene that will be produced from RMP-2 units.
Commissioning of S-1129 will allow LPG blending within the south spheres area without the need
to transfer to north LPG spheres, thus enabling the refinery to simultaneously load to LPG vessels.
After implementation of the project, the increase in storage capacity will provide the refinery
enough buffers to handle the increase in LPG and Propylene production in case of product lifting
delays thus avoiding unnecessary flaring of products. This project will also provide spare storage to
receive high pressure LPG and Propylene in case of PRU-2 shutdown.
As part of the project, contractor is tasked to prepare detailed engineering and construction of a
remote retention basin for all the south spheres to provide adequate drainage in an event of PSV
relief during a pool fire scenario.
Proper design of drainage and spill containment system is important in LPG storage facilities as
these handle large quantities of highly flammable liquids. When these products are accidentally
released and ignited, pool fires can be formed which can result in overpressure due to vapor
generation caused by the rapid boiling of liquid contents.
Generally, the size of a remote retention facility is determined based on the largest volume
calculated from the following scenarios below as cited in Section 5.2 of GP 09-01-01 (Spacing and
Dikes for Storage Vessels and Tanks):
The liquid volume remaining after initial vaporization from vessel spill or from the spillage
of the vessel assuming that the vessel is full, and its contents are at a temperature equal to
the lowest 24 hour mean temperature.
Fifty percent (50%) of the volume of the vessel for vessels storing liquids with RVP of 100
psia (690 kPa) or less.
Twenty five percent (25 %) of the volume of the vessel for vessels storing liquids with RVP
greater than 100 psia (690 kPa).
From the criteria above, it has been identified that the size controlling scenario for the remote
retention basin is from an LPG leak with estimated RVP of 623 kPaa. With the 5962 m3 being the
largest LPG sphere capacity, the remote retention basin working capacity is estimated at 2980 m3
(50% x 5962).
Nonetheless, simulation results indicate that at ambient conditions, the likelihood of a propylene or
LPG pool fire forming below the sphere is unlikely and that the leaking sphere contents will
immediately vaporize. Thus, there is no expected accumulation of liquid in the event of propylene
or LPG sphere leak.
In consideration with the determined retention pond size, a holdup capacity of 1.9 hours is
provided for accommodating firefighting wastewater in the remote retention basin. This
information should be considered by the Owner when preparing operating and emergency
firefighting response procedures.
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.4 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
1. Introduction
The New LPG Sphere, S-1129, and New Propylene Sphere, S-1135, will provide PBR with the
necessary product storage for LPG and Propylene that will be produced from RMP-2 units.
Commissioning of S-1129 will allow LPG blending within the south spheres area without the need
to transfer to north LPG spheres, thus enabling the refinery to simultaneously load to LPG vessels.
After implementation of the project, the increase in storage capacity will provide the refinery
enough buffers to handle the increase in LPG and Propylene production in case of product lifting
delays thus avoiding unnecessary flaring of products. This project will also provide spare storage to
receive high pressure LPG and Propylene in case of PRU-2 shutdown.
As part of the project, EPC contractor is also tasked to prepare detailed engineering and
construction of a remote retention basin for all the south spheres to provide adequate drainage in
an event of PSV relief during a pool fire scenario.
2. Objective
This document intends to provide details on the sizing basis for the remote retention pond as part
of the project scope.
3. Scope
Any information provided in the succeeding sections of this calculation is intended for use in this
project only. Results of this calculation is not final and is based on available data at hand. When
referring to this document, any new data unaccounted in the calculation should be evaluated and
the calculation revisited for impact on the presented results.
4. Acronym
API American Petroleum Institute
DCS Distributed Control System
EPC Engineering, Procurement and Construction
GP Global Practice (Exxon Mobil)
LPG Liquefied Petroleum Gas
PBR Petron Bataan Refinery
PRU Propylene Recovery Unit
PRV Pressure Relief Valve
PSV Pressure Safety Valve
RVP Reid Vapor Pressure
5. System Description
Proper design of drainage and spill containment system is important in LPG storage facilities as
these handle large quantities of highly flammable liquids. When these products are accidentally
released and ignited, pool fires can be formed which can result in overpressure due to vapor
generation caused by the rapid boiling of liquid contents. A PRV is normally provided to ensure this
excess pressure on the sphere is relieved and prevent unnecessary release of vessel contents after
normal conditions have been restored.
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.5 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
6. Remote Retention Pond Sizing Guidelines
In reference to Section 5.2 of GP-09-01-01, the remote retention pond size is governed by the
largest volume requirement on the following scenarios below:
6.1 The expected liquid volume remaining after initial vaporization, without taking any credit
for aerosol formation, from the spillage of the vessel assuming that the vessel is full and its
contents are at a temperature equal to the lowest 24 hour mean temperature which is at
14°C as per D.S. No. 18-0009-01.
6.2 Fifty percent (50%) of the volume of the vessel for vessels storing liquids with RVP of 100
psia (690 kPa) or less.
6.3 Twenty five percent (25 %) of the volume of the vessel for vessels storing liquids with RVP
greater than 100 psia (690 kPa).
7. Remote Retention Pond Size Evaluation
7.1 Remaining liquid volume after initial vaporization at 14°C (Minimum Ambient
Temperature)
A process simulation using Aspen Hysys was made to determine the physical properties of
the sphere contents at various conditions using the composition below:
Propylene Product – 100%Vol Propylene
LPG Product – 58% Vol Propane / 40% Vol Butane / 2%Vol Pentane
The following were observed:
Table 7.1-1: LPG and Propylene Condition Simulation Results
Sphere Content LPG Propylene
Storage Pressure, kPag 913 1460
Storage Temperature Ambient Min @ 14°C Ambient Min @ 14°C
Calculated RVP, kPaa 623 1573
Boiling Point (@ 0 kPag), °C -15 -47
Liquid fraction @ Ambient Min 0% 0%
*The determined conditions were taken from assumed LPG and Propylene composition. This table should
be updated when plant data becomes available.
Simulation results indicate that at ambient conditions, the likelihood of a propylene or LPG
pool fire forming below the sphere is unlikely and that the leaking sphere contents will
immediately vaporize. Thus, there is no expected accumulation of liquid in the event of
propylene or LPG sphere leak.
Further details in the simulation are provided in Attachment 1.
7.2 Remote retention pond capacity as function of sphere capacity
The table below provides the summarized geometric capacity of southern spheres:
Table 7.2-1: Southern sphere geometric capacities
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.6 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
Sphere Service Geometric Capacities, m3
S-1113 LPG 5535
S-1127 LPG 5962
S-1129 (New) LPG 5962
S-1117 Propylene 3591
S-1119 Propylene 3591
S-1121 Propylene 3591
S-1123 Propylene 3591
S-1131 Propylene 4445
S-1133 Propylene 4445
S-1135 (New) Propylene 4445
Using the criteria specified in item 6.2 and 6.3 above, the size controlling scenario for the
remote retention basin is from an LPG leak which is estimated to have an RVP of 623 kPaa.
With LPG RVP below 690 kPaa, the remote retention basin working capacity is estimated at
2980 m3 or fifty percent (50%) of the largest LPG sphere which is at 5962 m3.
7.3 Additional remote retention basin considerations
7.3.1 Firefighting wastewater loads
Although there is little to no likelihood of liquid hydrocarbon that can accumulate in the
remote retention basin, hydraulic load from firefighting wastewater should be considered.
An analysis of firewater demand on the new and existing sphere was conducted. In the
evaluation, firewater requirement is based on Section 10.3.1.3 and 10.3.3.3 of API 2510
recommended application rate of 0.10 gpm/sq. ft (0.24 m3/hr /m2) plus the amount
required for cooling of any adjacent sphere and a reserve capacity of 3 x 250 gpm (3 x 57
m3/hr) additional cooling stream.
When determining whether cooling water is needed for an adjacent vessel, the decision
should be based on (a) the amount of radiant heat it will receive from an adjacent fire and
(b) the maximum temperature that the unwetted shell section will reach when not cooled.
Fig. 1 of API RP 2510A 2nd Edition provides a conservative estimate of the minimum safe
distance between the center pool fire and adjacent vessel at which the maximum heat flux is
at 7000 BTU/hr-sq. ft.
A summary of the analysis made on the firewater requirement is shown on Table 7.3-1:
Table 7.3-1: Southern sphere Firewater Requirements
Adjacent
Sphere Sphere Sphere Total Firewater
Sphere
Sphere Service Diameter, Surface Cooling*,
Cooling,
Requirement,
m Area, m2 m3/hr m3/hr
m3/hr
S-1113 LPG 22.5 1590 559 555 1114
S-1127 LPG 22.5 1590 559 1028 1587
S-1129 (New) LPG 22.5 1590 559 709 1268
S-1117 Propylene 19.0 1134 448 666 1114
S-1119 Propylene 19.0 1134 448 943 1391
S-1121 Propylene 19.0 1134 448 597 1045
S-1123 Propylene 19.0 1134 448 0 448
S-1131 Propylene 20.4 1307 490 1028 1518
S-1133 Propylene 20.4 1307 490 986 1476
S-1135 (New) Propylene 20.4 1307 490 709 1198
*Includes reserve firewater cooling capacity for 3 x 250 gpm (3 x 57 m3/hr).
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.7 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
As observed in Table 6.3-1, there is additional requirement for adjacent sphere cooling as
there is not enough distance between the pool fire center and the nearest vessel. See
Attachment 2 and 3 for further details.
With the maximum firewater demand for the southern spheres estimated at 1587 m3/hr,
the retention pond as sized in item 7.2 provide a hold-up duration of 1.9 hours only. Owner
is advised to consider this limitation when preparing operating and emergency firefighting
response procedures. Also, existing oily and stormwater handling facilities should also be
assessed when the remote retention basin is to be connected to these systems.
8. Conclusion and Recommendations
8.1 There is little to no likelihood of liquid accumulation from leaks occurring from LPG and
propylene spheres. Based on various considerations applied, it can be concluded that the
minimum recommended remote retention pond working capacity is 2980 m3.
8.2 Available holdup of 1.9 hours for accommodating firefighting wastewater in the remote
retention basin should be considered by the owner when preparing operating and
emergency firefighting response procedures. In order to help increase holdup duration,
requirement for adjacent tank cooling should be carefully assessed during actual fire
emergency. The following methods can be applied to determine if cooling is needed:
Check for any abnormal pressure and temperature reading if available thru field
instruments or via DCS.
Apply a firehose stream to the suspected vessel and then remove it, if the shell stays
wet a few seconds or longer; further cooling at that time is not needed.
If water boils when it is applied to the shell surface, cooling should proceed until the
metal temperature is below the boiling point of water.
8.3 Existing oily and stormwater handling facilities should also be assessed when the remote
retention basin is to be connected to these systems in the future.
8.4 Although the determination on what constitute “adequate drainage” is generally subjective
as described in Section 4.4.13.2.4.2 of API 521. The following items promote a condition of
adequate drainage as outlined in Section 5.2 of API 2510:
The ground under and surrounding the sphere shall be graded to drain any liquid
spills to a safe area away from the vessel and piping. The grading shall be at a slope
of at least 1%.
The drainage system shall be designed to prevent liquid spilled from one sphere
from flowing under any other vessel and shall minimize the risk to piping from
spilled sphere contents.
The spill drainage area shall not contain equipment except as permitted by API
2510.
9. References
1. GP 09-01-01 V.2.0.0: Spacing and Dikes for Storage Vessels and Tanks
2. API Std 2510 8th Edition: Design and Construction of LPG Installations
New LPG and Propylene Spheres Piping, Electrical & Instrument Sheet No.8 of 8
Sizing Basis for LPG and Propylene Sphere Remote Retention Pond Doc. No. BRXX-X-XX01 Rev. 0
3. API Publication 2510A 2nd Edition: Fire Protection Considerations for the Design and
Operation of Liquefied Petroleum Gas (LPG) Storage Facilities
4. API Std 521 6th Edition: Pressure Relieving and Depressuring Systems
10. Attachment
1. LPG and Propylene Simulation Results
2. Firewater Demand Calculations
3. LPG Fire Adjacent Sphere Cooling Identification
