Mohamedia Power Plant Completes Replacement of All Turbine Bypass and Auxiliary Steam Valves

The national Moroccan utility O.N.E. (Office National d’Electricité) has awarded CCI a multi-million-dollar ( U.S. ) order to complete the replacement of all its HP and LP turbine bypass and auxiliary steam valves with multi-stage DRAG® technology control valves. The Mohamedia Power Plant (located approximately 20 kilometers from Casablanca ) is a 4 x 150-MW, coal-fired plant designed and built by ANSALDO in the early 1980s.

This large order for eight replacement turbine bypass valves for two units and two replacement auxiliary steam valves is particularly gratifying for CCI because it is based on the excellent service experienced with two other auxiliary steam valves supplied by CCI some six years ago.

Two additional 4-inch (100-millimeter) multi-stage pressure-reduction auxiliary-steam-control DRAG® valves are replacing original double-stage valves, which failed due to heavy vibration when in operation. The new CCI valves are designed (as were the other two previously supplied) for a flow of 30 metric tons/hour (66,000pounds/hour) at the turbine inlet pressure of 2000 psig (137BARG), a DP of 1675 psi (116 BAR), and 540 C (1000 F).

The eight replacement HP and LP turbine bypass valves incorporate CCI’s new SteamJet™ technology, which combines multi-stage pressure-reduction with integral desuperheater water injection. They replace the original bypass valves that also vibrated badly and leaked to the extent that they produced power reductions of up to 5 MW per unit. The four, 8-inch (200-millimeter) HP valves are designed for a flow of 165 metric tons/hour (365,000 pounds/hour) at the same turbine inlet pressure and temperature with a DP of 1430 psi (98BAR). The four, 14-inch (360-millimeter) LP valves are designed for a flow of 188 metric tons/hour (415,000 pounds/hour) at an inlet pressure of 484 psig (33 BARG) with a DP of 486 psi (32 BAR) and operate with the same temperature as the HP turbine bypass valves. All valves are provided with CCI pneumatic actuators.

Published in SOLUTIONS Fall 2000