BASIC DESIGN OF PYEONGTAEK LNG RECEIVING TERMINAL-II OF KOREA GAS CORPORATION LA CONCEPTION DE BASE DU TERMINAL METHANIER PYEONGTAEK-II Youngsoon Sohn Youngmyung Yang Insoo Yoon Sunghee Choi Gunhyung Choi R&D Division, Korea Gas Corporation 973, Dongchun-Dong, Yeonsoo-Gu Incheon, 406-130, Korea ABSTRACT The existing Pyeongtaek LNG receiving terminal I of Korea Gas Corporation (KOGAS) is the first LNG terminal in Korea which was constructed on a partially reclaimed land and started the commercial operation in 1986. This terminal has a storage capacity of 1,000,000 m 3 in 10x100,000 m 3 membrane containment LNG storage tanks and a gasification capacity of 2,020 ton/hour. KOGAS decided to construct the Pyeongteak LNG terminal II on a new reclaimed area located at the north of the existing LNG terminal I. This terminal will be designed for 10 LNG storage tanks and a vaporization capacity of 720 ton/hour. The first phase construction will be done from 2003 to 2008 for 4 LNG storage tanks of 140,000 m 3 and gasification process of 720 ton/hour. The jetty No.1 constructed in 1986 for the LNG terminal I will be newly assigned to the terminal II for unloading LNG. The send-out process can be extended to a capacity of 1,440 ton/hour. This paper outlines the basic design and features of the Pyeongtaek LNG terminal II conducted by KOGAS. Some important considerations are taken for a smooth linkage with the existing terminal I and efficient dealing with boil-off gas produced in the terminal I and II. RESUME Le terminal méthanier Pyeongtaek-I est le premier terminal en Corée du Sud qui a été construit sur une terre partiellement réclamée et a commencé l'opération commerciale en 1986. Ce terminal a une capacité de stockage de 1,000,000m 3 avec 10 réservoirs à membrane de 100,000m 3 et une capacité de regazéification de 2,020 tonne par heure. Très récement, KOGAS a décidé de construire le deuxième terminal Pyeongteak-II sur un nouveau domaine réclamé localisé au nord du terminal-i existant. Ce terminal-ii sera conçu pour 14 réservoirs de stockage et une capacité de vaporisation de 1440 tonne par heure. La première phase de construction sera faite de 2003 à 2008 pour 4 réservoirs de 140,000m 3 et le procédé de regazéification de 720 tonne par heure. La jetty No.1 PO-07.1
construite en 1986 pour le terminal methanier Pyeongtaek-I serai récemment assigné au terminal-ii pour décharger le GNL. Le procédé d envoie peut être étendu à une capacité de 1440ton/hour. Ce papier esquisse la conception de base et les caractéristiques du terminal methanier Pyeongtaek-II dirigé par KOGAS. Quelques considérations importantes sont prises pour un lien lisse avec le terminal-i et pour le traitement efficace du gaz d évaporation produit dans les terminaux- I et II. INTRODUCTION The existing Pyeongtaek LNG receiving terminal I of Korea Gas Corporation (KOGAS) is the first LNG terminal in Korea which was constructed on a partially reclaimed land and started the commercial operation in 1986. This terminal has a storage capacity of 1,000,000 m 3 in 10x100,000 m 3 membrane containment LNG storage tanks and a gasification capacity of 2,020 ton/h. KOGAS decided to construct the Pyeongteak LNG terminal II on a new reclaimed area located at the north of the existing LNG terminal I. This terminal will be designed for 10 LNG storage tanks and a vaporization capacity of 720 ton/h. This paper describes the basic design and characteristics of the Pyeongtaek LNG terminal II conducted by KOGAS. Some important considerations are taken for a smooth linkage with the existing terminal I and efficient dealing with boil-off gas produced in the terminal I and II. Figure 1. Overview of Pyeongtaek LNG Receiving Terminal I and II PO-07.2
OUTLINE OF PYEONGTAEK LNG TERMINAL II The Pyeongtaek LNG receiving terminal II is located on a new reclaimed area located at the north of the existing LNG terminal I. This terminal will be designed for 10 LNG storage tanks and a vaporization capacity of 720 ton/hour. The first phase construction will be done from 2003 to 2008 for 4 LNG storage tanks of 140,000 m 3 and gasification process of 720 ton/h. The jetty No.1 constructed in 1986 for the LNG terminal I will be newly assigned to the terminal II for unloading LNG. The send-out process can be extended to a capacity of 1,440 ton/h. The terminal will receive liquefied natural gas (LNG) from several different locations on the Pacific Rim such as Indonesia, Malaysia, Brunei, Australia and Alaska. LNG will be stored and regasified in the terminal and then exported to a gas transmission network. The project will be developed in phases with consideration being given to future expansion. The final terminal configuration is anticipated to be one train of identical storage and sendout capacity. The train will have a peak sendout of 720 ton/h of natural gas and a minimum of 200 ton/h. There are two sets of LNG vaporizers, seawater vaporizers and submerged combustion vaporizers. A metering station is provided on the sendout stream. Table 1. Main Facilities of Pyeongtaek LNG Terminal II Phase I Phase II Unloading Berth Jetty No. 1 (Terminal I) - Unloading rate : 11,000 m 3 /h LNG Storage Aboveground 9% Ni type 140,000 m 3 x 10 Aboveground 9% Ni Type 14 Storage tanks Vaporizer Open-rack type, 180 ton/h x 2 Submerged type, 90 ton/h x 4 Open-rack type, 180 ton/h x 5 Submerged type, 90 ton/h x 6 Sendout Capacity 720 ton/h 1,440 ton/h BASIC ENGINEERING OF PYEONGTAEK LNG TERMINAL II Process Design Ten 140,000 m 3 (working volume) LNG storage tanks are provided. The tanks have a design pressure of 29 kpa and a specified heat leakage rate of 0.075 wt% per day of tank contents based on a full tank of liquid methane inventory. Connections to the tank for filling and emptying are made through the tank roof. Provisions have been made in the design for top as well as bottom unloading into the storage tanks. A number of alarm and shutdown devices are incorporated in the design in order to provide maximum safety for the tanks. During the ship unloading the pressure in the tank will be maintained at maximum pressure of approximately 25 kpa and LNG with a saturation pressure of 17.5 kpa will be unloaded and all vapor generated will be recovered. At the beginning of the unloading operation, LNG from the ship is used to cool down the unloading arms and auxiliary equipment. The design unloading rate is 11,000 m 3 /hr. PO-07.3
Between LNG tanker arrivals, the heat leakage into the unloading system is continuously removed by circulating sendout LNG through the unloading system before it enters the recondenser. Part of the LNG from the discharge of the LP sendout pumps flows first through the sendout headers in the tank area, into one of the unloading lines, all the way to the jetty and back to the storage area via the other unloading line and then to the recondenser. During ship unloading, all the discharge from the storage in-tank pumps pass directly to the recondenser. During ship unloading, the heat input into the system consists of heat of pumping as well as ambient heat leak. Boil-off gas from the storage tanks is routed via the boil-off gas header to the boil-off gas compressors. The boil-off gas header balances the pressures between the ten tanks. For the future expansion of the LNG storage capacity additional compressors will be required. At the beginning of ship unloading the vapour return line may be at ambient temperature. LNG is injected into the ship return vapor at the dock desuperheater to ensure the vapor passing to the ship is below -140 C. A jetty knockout drum is provided to remove any remaining liquid downstream of the desuperheater. A compressor suction knockout drum is provided upstream of the boil-off gas compressor to disentrain any liquid in the boil-off header. A desuperheater upstream of the compressor suction drum is provided to ensure the compressor suction temperature is below -80 C at low boil-off gas flows. LNG sendout liquid from the storage tanks is pumped by LP LNG pumps located in the storage tanks via the sendout headers to the recondenser. In the recondenser, compressed boil-off gas is condensed into the subcooled sendout LNG. The LP LNG Pumps are each capable of pumping 330 m 3 /hr LNG. The boil-off gas and LNG enter the inner cylinder from the top of the recondenser and are contacted in the packing. The bed liquid level will vary with pressure and the vapor/liquid load on the recondenser. Recondenser pressure is maintained by passing a portion of boil-off gas from the compressors around the packed bed section of the recondenser. The recondenser also acts as a liquid buffer volume for the sendout pumps. The LNG from the recondenser is directed to the sendout pumps which discharge the LNG at approximately 7.9 MPa via the sendout headers to the vaporizers. LNG is gasified in the vaporizers which operate at approximately 7.7 MPa. The vapor from these units will be at approximately 0 C. There are two sets of LNG vaporizers, seawater vaporizers and submerged combustion vaporizers. The two seawater vaporizers use seawater to provide a duty equivalent to a sendout of 180 t/hr of gas each. Four submerged combustion vaporizers are provided each capable of sendout of 90 t/hr of gas. Vaporized natural gas is exported via a dedicated pipeline to the gas network. A metering station is provided on the sendout stream. PO-07.4
Figure 2. Process Flow Diagram for Pyeongtaek Terminal II Plot Plan This layout envisions installation of up to 14 storage tanks and 11 vaporizers. The distance between LNG storage tanks and property limits is determined in accordance with the requirement of NFPA 59A and the domestic regulation. Further considerations with respect to location of storage tanks are; economy of piping from jetty, piperack access, pipe expansion and displacement, sequence and method of tank construction. Spacing for HP sendout pumps, vaporizers, BOG compressors is in accordance with NFPA 59A and is sited to ensure that incident heat fluxes from tank do not exceed 8 kw/m 2, unless some form of fire protection is provided. The location of the metering station ensures an economical route for the export line. Convenient access to metering station is provided from plant road. And also sendout header tie-ins for the terminal I and II ensures an economical route for each process lines. The flare stack provided for the terminal II is designed to cover the relief loads for the terminal II. The flare stack is to be located on a jetty such that the sterile zone will be over water. The utility area encompasses the control room, electrical sub-station and all non hydrocarbon equipment. The items such as the electrical sub-station and nitrogen and instrument air packages are located to best suit the location of process equipment they serve. Additionally they are located in a safe area not requiring explosion proof electrical equipment. PO-07.5
Process Tie-ins for Terminal I and II Figure 3. Plot Plan for Pyeongtaek Terminal II The jetty 1 for the LNG terminal I will be assigned to the terminal II for unloading LNG. The jetty 1 will normally unload ships into tanks in the terminal I. Crossconnections with the existing unloading headers allow unloading from jetty 1 into any tanks of the terminal II. Temporary piping connections are to be provided from the existing LP sendout header of the terminal I to the suction of the new HP LNG sendout pumps of the terminal II. This will allow LNG from the terminal I to be routed to the HP pumps and vaporizers in the terminal II before the storage tanks of the terminal II are installed. During normal operation the boil-off gas which is generated in the tanks can be condensed in the recondensers for each process lines of the terminal I and II. For efficient dealing with boil-off gas produced in the terminal I and II cross-connections with the BOG suction of the recondensers are to be provided. In emergency operating mode recondensers either process trains of the terminal I and II can handle the boil-off gas from all the tanks of the Pyeongtaek LNG receiving terminal. PO-07.6
Figure 4. Sendout System Tie-ins for Terminal I and II CONCLUSIONS This Basic Engineering contains the compilation of the design data required for the detailed work of the Pyeongtaek LNG receiving terminal II. The process system has been designed sendout rate of 720 ton/h of revaporized natural gas and the plot space has been allocated for 14 storage tanks. The basic engineering of Pyeongtaek LNG receiving terminal II is not only a technically complex operation demanding smooth process linkage to the terminal I, but is also a installation and operation on the phases in advance of new tankage installation in the terminal II. The detailed engineering data and vendor data associated with the equipment eventually selected will complement the basic design package and the contents of the package will be kept under continuous review and modified as detailed engineering and procurement progress. PO-07.7