Caspian crude oil line gets power systems

June 18, 2001
Installation of 113 grid-connected power systems along the 1,500-km (932-mile) Caspian Pipeline is in the final stages, according to supplier Northern Power Systems, Waitsfield, Vt., which is under contract to the Caspian Pipeline Consortium (CPC).
This power system supplies a block valve along the right of way of the Caspian Pipeline in Kazakhstan. Photograph from Northern Power Systems, Waitsfield, Vt.
Click here to enlarge image

Installation of 113 grid-connected power systems along the 1,500-km (932-mile) Caspian Pipeline is in the final stages, according to supplier Northern Power Systems, Waitsfield, Vt., which is under contract to the Caspian Pipeline Consortium (CPC).

CPC consists of 11 owners, the largest of which is Chevron Corp. and including the governments of Russia, Kazakhstan, and Oman. Fluor Daniel Eurasia, CPC's engineering and project manager, provided Northern's principal technical and logistics interface.

Installation of the systems began in November 2000 and will be completed this summer.

Functions; backup

Referred to as GridTie systems, they provide power along the pipeline. Northern's contract calls for delivery of 113 fully integrated and tested systems, delivered to the Black Sea port near Novorossiysk.

Click here to enlarge image

The systems were designed in Vermont but manufactured and tested at CellXion-Lightweight Division, Wagoner, Okla., which provided the shelter buildings (Fig. 1).

The systems were designed for unmanned operation and are connected to a 10-kv transmission line that runs parallel to the pipeline. Depending on their function, says Northern, they supply conditioned power for cathodic protection, telecommunications, supervisory control and data acquisition (SCADA), security, and valve actuation.

These systems provide all of the electrical hardware that connects monitoring and control devices to the pipeline computer network, thereby allowing a remote operator continuously to monitor and control all critical system performance parameters, says Northern Power.

Such parameters include valve function; cathodic protection; environmental data; battery temperature and voltage; heating, ventilation, and air conditioning; power flows; and internal subsystems.

In a loss of power from the commercial grid, the pipeline's operation control center receives automatic notification. Simultaneously, the power system loads are seamlessly switched over to back-up battery banks.

The system has two separate battery banks. The first is a 48-v (DC) bank that supports the SCADA and telecommunication loads for up to 48 hr after grid failure. A completely separate battery bank configured at 360 v (DC) is specifically to ensure 100% power availability in the event that main line block valve actuation is required.

The system's programmable logic controller will automatically shed all non-critical loads, thereby ensuring the batteries can support the critical loads for as long as possible, the company says.

Configurations

The 113 different power systems are grouped into five different configurations to meet the pipeline's operational requirements, says Northern Power. Most of the systems are part of the main line block valve system.

This system provides power, control, and SCADA interface for each main line block valve. It also includes a cathodic-protection unit to help prevent corrosion along with providing rectified and conditioned DC power for CPC-supplied telecommunications and security equipment.

The primary power supply is a 10-kv (AC) grid interface. From a customer-supplied voltage transformer, Northern takes 380 v (AC), three-phase, 50-hz power. Noncritical AC loads are run directly off this incoming power.

For all critical SCADA, cathodic protection, security, and telecommunications loads, Northern rectifies this incoming AC into 48-v (DC) power.

A valve-regulated lead-acid battery bank, referred to as the "Telecom battery bank," stores up to 48 hr of back-up energy in the event of grid failure; 24 v (DC) power is also available through a DC voltage converter.

Main line block valve actuation requires 380 v (AC), three-phase, 50-hz power. Under normal conditions, says Northern, if actuation is required, this power will come directly off the incoming grid power. The system is equipped with a separate UPS back-up system specifically designed for main line block valve actuation in the loss of grid power.

It consists of a rectifier that takes the incoming AC and maintains a 360 v (DC) battery bank in a topped off condition at all times. In the event of MLBV actuation, the SCADA system sends the signal and energy is immediately taken from the battery bank and changed back to 380 v (AC) through an inverter to provide instantaneous power for actuation.

Northern says the system is designed so that dual-cycle actuations can take place before the battery is fully discharged. Once grid power is restored, the battery will automatically be brought back up to a topped off condition.

Four variations of the main line block valve system configuration were for the following applications:

  • Double main line block valve stations (four systems).
  • Future pump stations (eight systems).
  • Launcher and receiver stations for pipeline scraper applications (six systems).
  • Radio and telecommunications stations (19 systems).

Statoil tankers to receive VOC-reduction system

Two shuttle tankers moving crude oil for Statoil from Norwegian fields will be equipped with systems that reduce emissions of volatile organic compounds (VOCs), the company announced last month.

"This marks the first investment in such recovery technology on vessels in ordinary operation as part of efforts to reduce the negative impact of these emissions on the climate," said Statoil.

Ugland Nordic Shipping ASA's Juanita and Navion Shipping AS's Knock An transport crude from Statfjord and Gullfaks fields in the North Sea.

Statoil has been working since the early 1990s to find solutions for reducing the amount of VOCs vaporizing from offshore cargoes, said the company.

Together with a number of other companies, it has already invested in pilot projects on Knutsen OAS Shipping's Anna Knutsen and Navion's Navion Viking.

Statoil project manager Jan Terje Mathisen said the company is adopting the best available technology for such VOC recovery installations. It signed a letter of intent with Kværner ASA on delivery of nonmethane VOC plants.

These make possible the recovery of light hydrocarbons, such as ethane, propane, and butane, which vaporize from crude oil during offshore loading, and return them to the cargo.

Statoil is considering similar measures for other fields it operates and looking at other ways of reducing VOC emissions.