ATLANTIC BASIN
8.9 UTILITY SYSTEMS Process Heating Medium System
A process Heating Medium System (HM) will be provided to service the process utility heating requirements. The heat transfer fluid will be 30 wt% ethylene glycol aqueous solution used in the closed loop system. Operating conditions for the HM are as follows:
Hot Supply Temperature: 180°F
Hot Supply Pressure: 55 psig The equipment comprising the HM System includes:
1x100% HM Surge Drum (V-5)
2x100% HM Circulation Pumps (P-5A/B)
1x100% HM Storage Tank (TK-2)
1x100% HM Transfer/Unloading Pump (P-6)
2x100% Slip stream HM 5 micron Filters (F-1A/B)
2x100% Direct Fired HM Heaters (HTR-1A/B) Seawater System
A Seawater System will be provided to supply seawater to the LNG Open Rack Vaporizers.
Three 50% Seawater Pumps (P-7A/B/C) will be installed on the jetty platform. These pumps will be a vertical can pump design driven by a top mounted electric motor. Minimum flow control protection will be provided.
Large self-cleaning seawater intake screen will be provided surrounding the pump inlets. The screens will be designed to meet environmental criteria to prevent small sea life and other biological materials from entering the Seawater System. Velocity through the screens will be limited to 0.5 feet/second. A manual filter screen trap will also be installed at the discharge side of each Seawater Pump.
A hypochlorite unit will be provided to chlorinate the seawater which prevents the growth of algae and other biological life forms within the system. Chlorination injection points will be provided at the suction of each Seawater Pump and at the ORVs for “shock chlorination”. Chlorination concentrations will be controlled to comply with the environmental regulations.
Warm seawater is supplied by the pumps at a pressure of 50 psig and flows to the ORV units. Cool seawater exits from the bottom collection basin of the ORV at a temperature of approximately 65oF (18.3oC) and flows by gravity to the seawater outflow discharge back into the sea. The seawater outflow discharge pipe returns will be designed to discharge the cool seawater at a subsea depth of approximately 250m where the ambient seawater temperature is approximately equal to the seawater effluent discharge temperature. Environmental regulation guidelines for thermal discharge require that the temperature at the edge of the thermal mixing zone (defined to be 100m from the point of discharge) be within +/-3oC of the natural ambient temperature. A site specific EIAS will need to be prepared to validate compliance with environmental regulation guidelines.
Pressure Relief and Flare/Vent Systems
Flares/Vents will be sized for the maximum credible relief scenario. The following flare systems are provided:
HP flare/vent designed for dry and cold vapor and blowdown; and
LNG marine/storage flare/vent designed for low pressure boil-off gas from the storage and jetty.
Flare/Vent systems will be designed for long term reliable operation from the minimum to the maximum flaring/venting rate. Flared/Vented gas will be metered to support environmental reporting requirements.
Design of the flare/vent stacks should make allowance for a solar radiation contribution of 0.8 kW/m2. The flare/vent tips will be located such that the radiation limits specified in API RP 520 and API RP 521 are not exceeded. Radiation level from the flares/vents will be limited to the following maximum radiant heat exposure criteria:
The HP flare/vent stack will be an elevated derrick supported structure. All flare/vent stacks will be retractable type that provides flexibility to lower down tips for maintenance. The HP flare/vent system will be designed to accommodate future expansion.
The HP flare/vent system design will also facilitate controlled depressurisation of the sendout pipeline and pig launcher.
A mechanical interlock PSV valve locking system (uniquely keyed) will be installed for pressure relief services equipped with multiple PSVs to ensure clear indication to operating personnel that an adequate number of PSVs are on-line.
Fuel Gas System
The Fuel Gas Supply System will be designed in combination with all consumers to enable all possible fuel gas composition changes due to operational upsets to be effectively managed without resultant loss of consumers. Fuel gas heaters will be provided for both cold start and normal operation.
The Fuel Gas System provides gas for the HM Heaters as well as blanket gas and purge gas for to the flare headers. Where possible, blanketing gas/pad gas uses nitrogen rather than fuel gas. The required minimum fuel gas pressure is 30 psig.
For startup, fuel gas is provided from the BOG system. Since electrical power will be supplied from the Aqualectra power grid, BOG compressors (driven by electric motors) will be operable for cold start.
Utility and Instrument Air System
Compressed air will be provided to supply utility air and to feed the instrument air-dryer package for the production of instrument air and nitrogen for the Terminal. Compressed air will be supplied from two electric motor driven air compressor packages, each of which is capable of supplying 100% of the total air required for the Terminal. All compressors will supply oil-free air.
Utility Air will meet the following specifications:
Pressure 140 psig
Maximum Temperature 130°F
Instrument quality air will be produced by an instrument air-dryer package (2 x 100% packages).
Instrument Air will meet the following specifications:
Normal Pressure 125 psig
Minimum Pressure 85 psig
Maximum Temperature 130°F
Maximum Dew point -40°F
The Instrument Air Receiver and Plant Air Receiver will be sized to provide a minimum of 15 minutes of surge capacity between the normal and minimum operating pressures based on the design air flow rates including design margin. Compressed air prioritization and secured instrument air supplies shall be implemented to maximize instrument air availability.
Nitrogen System
A nitrogen generating system will be furnished to supply the nitrogen requirement for the equipment purging, pad gas, compressor gas seal, blanketing, inerting and additional requirements during shutdown and turnarounds.
The primary system (a membrane-type, or equal) will use instrument air for nitrogen generation, and shall contain multiple membrane units such that one individual membrane unit can be removed from service while the balance of the membranes continue to supply nitrogen at the full design rate. Nitrogen produced will meet the following specifications:
Supply pressure 110 psig
Maximum Oxygen Content 1.5% - 4%
Minimum Nitrogen Content 96% - 98.5%
Oil & Hydrocarbon Content None
Maximum Water Content 30 ppmv
The nitrogen generating system uses dehydrated instrument air as feed gas. The instrument air is from an instrument air-dryer package that continuously delivers -40ºF dew point air at normal operating pressure.
Using the dried instrument air as the feed to the nitrogen generator ensures that the nitrogen produced is sufficiently dry for the various applications and operations within the LNG Plant.
A secondary (back-up) liquid nitrogen system may be provided, designed to furnish the nitrogen requirements for startup purging.
Wastewater Treatment
Wastewater generated from the operation of the Terminal will include sanitary sewage, oily storm water, process oily water and clean storm water runoff. The collection, treatment, reuse and/or discharge of the wastewater shall be designed to meet the effluent discharge limits established by the regulatory authority.
Bulk Storage
HM storage (ethylene glycol/water solution) will be sized based on 6 months of average HM losses, considering that the volume of the standard delivery container is 20 m3.
Diesel fuel will be stored on site for supply to diesel engine driven equipment including the firewater pumps and the emergency generator. Storage volume shall be sized to hold the volume from one large road tankers (34 m3 capacity).
Storage for other miscellaneous bulk chemicals required in operating the facility such as lube oil will be provided.
Electric Power Supply and Distribution
Primary electric power required during the construction and operational phases of the project will be supplied from Aqualectra’s power grid. The maximum peak power demand for the Terminal will be approximately 5,250kW when a ship is unloading. During normal operations, power demand will be approximately 1,800kW. The electrical power distribution will be supplied at the voltages and frequency listed in Table 8.9-2.
Table 8.9-2 Electrical Power Distribution
Service Voltage Phase Frequency
(Hz)
Medium Voltage Power 6.6 kV 11 kV
Emergency power will be supplied from a diesel driven Emergency Generator to be installed at the Terminal. The calculated emergency power load is approximately 625kW. The critical services that are included in the emergency power load are shown in Table 8.9-3.
An uninterruptible power supply (“UPS”) will be installed to provide a reliable source of power for:
Critical instrumentation and control;
Security;
The telecommunication systems;
Fire and gas detection;
ESD systems; and
Emergency lighting.
The batteries for all of the UPS systems will be sized based on supplying the rated load of the UPS for a minimum of 30 minutes.
Workshop/Warehouse/Lab 220V/110V 1 50 96
Terminal & Jetty Lighting 220V 1 50 200
MCC Building 220V/110V 1 50 36
Guard House 220V/110V 1 50 9
Total Emergency Load 625
Lightning protection and transient over-voltage will be provided in accordance with applicable codes and standards.
Water Supply Systems
There is no identified source of ground or well water available at the Terminal site. Water supply to the Terminal will be required for wash water, potable water and sanitary use. Additional information must be gathered to determine the best method for supplying water to the Terminal. Aqualectra may currently have water supply sources currently available at the existing Bullen Bay Oil Terminal Facility which can be tapped into for use at the LNG Terminal.
8.10 SAFETY SYSTEMS