PROJECT PROFILE: MT PIPER POWER STATION - NSW AUSTRALIA

Overview

Mt. Piper Power Station is owned and operated by Delta Electricity, a state owned corporation of the New South Wales Government. Located 125 km west of Sydney, the 1400 NW station comprises two coal-fired turbo-generators. Cooling water for two, natural draught hyperbolic cooling towers is pumped from the Lyell Dam and Thomsons Creek Dam on the Coxs River, 20km from the power station.

A 4,800 m³/d OSMOFLO dual membrane treatment plant built in 2007 and expanded in 2009 removes particulate matter and dissolved solids from the cooling water circuit and eliminates the need to discharge cooling tower blowdown water to the environment.

Process Description

The water from the cooling tower forebay contains a total suspended solids (TSS) concentration of up to 100 mg/L and total dissolved solids (TDS) concentration of up to 3,600 mg/L. Feedwater is pumped through a 200 micron strainer which removes larger particles and fibrous matter to protect the MF system. The feedwater may be dosed with acid if required to ensure that it is non-scaling prior to being fed to the MF module.

Suspended solids are then removed by a five-train, skid-mounted Siemens Memcor MF system. Filtrate from the MF units is fed to a filtrate tank, which provides a buffer between the RO and MF systems, allowing sufficient volume for the RO to run while one MF unit is backwashing.

RO feedwater is dosed with antiscalant and sodium metabisulphite to remove any residual chlorine before it is introduced to the five-train, single-pass RO system that operates at a 75 percent recovery.

Permeate is returned to the cooling water circuit, and MF backwash water, RO concentrate and chemical cleaning wastewater are discharged to the brine ponds. The salt is ultimately removed by the power station’s brine crystallizers and transported offsite for disposal.

The system is equipped with clean-in-place facilities for periodic acid and alkaline RO membrane cleaning.

Plant Operation

The desalination plant is designed for fully automatic, unattended operation and is remotely monitored by a proprietary OSMOFLO control system. Off-site management of operations is conducted via a telephone line connection with all data and alarms logged and fed into a data management system. When a critical fault occurs, a service number is automatically dialed, triggering Technical Support to dial in, diagnose the fault and reset the plant.