Jan-2013

Operator training simulator for a multi-product fuels pipeline

An operator training simulator for a fuel products pipeline system was developed and delivered before the pipeline was completed to train personnel in operations

Santosh Alladwar, Cordell Chapman, Billy Mayo, Surajit Dasgupta and Javier Vazquez-Esparragoza, KBR
Keone Jackman, Petroleum Company of Trinidad and Tobago Limited
Daniel Vogt, Krohne Oil and Gas

Article Summary

As part of a larger project to design and build a new multi-product fuels pipeline system for Trinidad and Tobago, an innovative operator training simulator (OTS) was developed that allows highly realistic training of the pipeline operators in all phases of operations prior to actual startup of the pipeline and for continuous training after startup. The pipeline, owned by a consortium of Trinidadian entities, including the Government of Trinidad and Tobago, the National Gas Company of Trinidad and Tobago (NGC), the Trinidad and Tobago National Petroleum Marketing Company (TTNPMC) and Petroleum Company of Trinidad and Tobago (Petrotrin), is designed to deliver up to 36 000 b/d of multiple fuel products (gasoline, diesel and aviation fuels) at peak by a state-of-the-art automated pipeline system roughly 47 km in length from the island’s Petrotrin West refinery to a new distribution terminal in Caroni County in the central part of Trinidad. Also included in the distribution system is a new 11 km pipeline to deliver aviation fuel from the Caroni terminal to Trinidad’s Piarco Airport (see Figure 1).

The pipeline system is being built to ensure secure and on-time delivery of fuel products to key points on the island, which otherwise relies on delivery by trucks. To ensure the quickest delivery times, the pipeline also employs a new “pigless” delivery system that loads one liquid product immediately behind another in a continuous, seamless fashion. The proper operation of the pipeline in this pigless mode is ensured by a leak detection system (LDS) and batch management system (BMS) from Krohne Oil and Gas, a company specialising in metering skid solutions and computational pipeline monitoring (CPM) pipeline leak detection. The LDS and BMS were integrated into the OTS, which would be used in tandem with the pipeline control system (PCS) and the terminal automation system (TAS) to plan, schedule and track product batches, keep track of the feed and product tanks, as well as provide alarms and/or advice to operators on abnormal conditions, and continuously detect for potential pipeline leaks. As some of these systems are new and to some extent custom built for this project, it was agreed and planned in advance to have an OTS to aid in the rapid familiarisation and training of operations personnel.
   
Process overview
The batch of refined products from Petrotrin West Refinery storage tanks consisting of unleaded RON92 gasoline, unleaded RON95 gasoline, diesel and Jet A-1 fuel will be metered and transferred by pipeline pump using individual booster pumps for each product.
The preliminary batch sequence would be as follows:

Jet A-1 → Diesel → RON 92 → RON 95 → RON 92 → Jet A-1

This batch sequence will be transferred to the Caroni facility, the distribution centre, using a pipeline pump via an 8in multi-fuels pipeline. Before transferring to the Caroni facility’s storage tanks, all the fuels will be metered at a metering skid entering the pipeline. The meter will be used to control the mainline pumps, while the tank gauging systems will be used for custody transfer. The general operation is designed to run with no pigs; however, an additional pig launcher was built to launch an intelligent/batch pig in cases when this operation was needed.

As soon as a batch arrives at the Caroni facility, it will be diverted to the appropriate destination tank by the operator based on the interface detection. For batch interface detection, density is the primary parameter used. Two densitometers are used to detect the interface of the multi-fuels. The first interface detector is installed 4.4 km from the Caroni facility to alert the operator about the product coming in the pipeline. The operator may use a second interface detector, located at the Caroni centre, to decide the correct time to switch valves to transfer the product into an appropriate tank.

The liquid fuels interface is one of the most important parameters to measure at the Caroni facility in order to transfer the product into an appropriate tank. When the multi-fuels are transferred using one pipeline, an interface mixture is generated. The interface mixture/off-spec product can be diverted to slop tanks or to the lower-quality product tank. Two slop tanks are provided to accommodate the interface — a high flash slop tank and a low flash slop tank. The interface/off-spec product from the slop tanks is trucked back to the Petrotrin West refinery for reprocessing.

Fuel from the individual storage tanks is transferred to (truck) loading bays using individual transfer pumps for each product.

For the batch control of two grades of gasoline — RON 92 gasoline and RON 95 gasoline — their physical properties would be too close to reliably differentiate the products based on density alone. Optical interface detectors (OIDs) are also installed near to the densitometers. The two gasoline grades are dyed for taxation purposes, resulting in distinct optical signatures (primarily colour), which the OID can distinguish and signal to the operator. Additionally, the flow meter count could be utilised to guide the operator.

An additional dedicated pipeline 8in diameter and 11.2 km length is installed to transfer the Jet A-1 from Caroni to the Piarco facility. There are two isolation valves installed on the pipeline because of a river crossing, one valve at each side of the river. A 600-gallon-per-minute capacity pump can deliver jet fuel from the Caroni distribution centre to Piarco Airport.

Simulator development
The OTS was designed and delivered by KBR’s Advanced Chemical Engineering group with support from the Pipeline and Operations groups. Overall, the OTS consists of four components:
•  A custom dynamic model of the pipeline system (resembling actual pipeline operation) and an “instructor station” to train the operator, with various features such as operating training on field devices. The safety instrumented system (SIS) logic was also implemented in the model. The SIS hardware/software was not replicated because it was possible to model its functionality with the pipeline software. A portion of the pipeline system, the TAS, handling loading on logistics operations, was not included in the OTS system. Only some of the main operations screens were simulated
•  A BMS and LDS identical to the real pipeline’s BMS and LDS systems
•  A dedicated Emerson DeltaV distributed control system (DCS) identical to the real pipeline’s DCS
•  DeltaV Operator consoles identical to the actual pipeline’s consoles.