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Kaeng Khoi 2 Power Plant Water and Wastewater treatment system

A complete water treatment system for one of Thailand’s most advanced power plants

Client
Alstom
Contract Value
SGD$11M
Project Duration
2005
Estimated Completion
2007
Location
Saraburi, Thailand
Project Overview

Situated in the Saraburi province north of Bangkok, Kaeng Khoi 2 is a gas-fired thermal power plant with a generating capacity of 1468 Mega Watts, 7.5% of Thailand’s total power consumption. This gas fired, combined cycle type plant uses 2 x 734 Mega Watt trains of combined cycle gas turbines and two heat recovery and steam generation systems, feeding one common steam turbine. The facility which includes a leading water treatment system was designed to meet Thai and World Bank environmental regulations.

UGL was contracted by Alstom to build a world class water treatment system for the Kaeng Khoi 2 Power Plant which included facilities for pre-treatment, demineralisation, and wastewater processing.

The Challenge

The challenge for Alstom was to secure a consistent, reliable source of water for cooling tower make up that was also cost effective and sustainable. A water treatment solution, a critical element in refining raw cooling water, was also required to soften or remove solids, and in this case deal with organics.

With properly treated water, the potential for scaling in power plant cooling towers is significantly reduced. This decreases cooling circuit cleaning requirements, extends the life of the cooling equipment and reduces the cooling tower blowdown flow to the environment.

Alstom also needed to find a solution for treating effluent-steam generated from the purge of flue-gas desulfurization (FGD) scrubbers to reduce environmental impact. This wastewater can be challenging to process as it contains heavy metals, suspended solids, and salts such as calcium, magnesium, and sodium chloride.

The Solution

UGL’s extensive expertise in delivering complete water and wastewater solutions for the power generation industry was utilized for this project. The solution consisted of 3 key elements which included a pre-treatment plant, a demineralization plant and a wastewater plant.

The pre-treatment plant was constructed to produce softened clarified water for the cooling tower water make up system critical for the plants operation. Two 27 metre diameter lime softening re-activators, each capable of producing 1250 cubic metres per hour of treated water were utilised with associated chemical dosing systems. This included calcium hydroxide for softening, sodium hypo-chlorite for disinfection and oxidizing, polymer for flocculation, and sulphuric acid for the final pH correction. The sludge from the plant is then further treated by a thickener and dewatered through belt presses.

The demineralization plant then further treats water for the boiler make up water system. Clarified water from the pre-treatment plant is treated with sand filters to remove fine particulates, follow by reverse osmosis for Total Dissolved Solids (TDS) removal.

An ultra violet reactor is the employed to break the Total Organic Carbon (TOC) before final polishing is performed in a mixed bed (to the required specification of water quality of less than 0.1 µ S/cm, Total Organic Carbon < 0.3 parts per million and Silica < 0.01 parts per million).

For the final stage of water treatment, UGL delivered a wastewater plant consisting of two units of Dissolved Air Flotation (DAF) each capable of treating 315 cubic metres an hour of highly refined wastewater (maximum of 150 parts per million of suspended solid in the effluent). The wastewater is then coagulated with a coagulant in two stage flocculators and followed by dissolved air flotation with final pH correction and chlorination before discharging. Sludge is then pumped back into the dewatering system.

UGL’s scope of work in delivering this solution included project management, overall plant and process design, equipment installation, guarantees, instrumentation and SCADA integration, testing and commissioning (except for the civil construction).

Key Outcomes and Benefits

From systems that treat cooling tower make up and boiler feed to wastewater treatment systems that minimize discharge to the environment, UGL delivered a comprehensive and cost effective solution to service Alstom’s power generators that ensures a consistent and reliable supply of quality water.

Focusing on system performance, compliance with process and environmental requirements as well as long-term cost-effectiveness, UGL was able to meet the most demanding standards of reliability, safety and quality when delivering this water treatment solution.

Key successes included:

  • Overall power plant system reliability through establishing a pre-treatment water plant that would produce high quality cooling water which avoided costly downtime through proven technologies and robust engineering systems.
  • Efficiency by developing solutions that help the client generate the maximum amount of electricity using the minimum amount of resources.
  • Delivering engineering systems that ensure compliance with environmental legislation while reducing the plant’s water footprint.
  • A dependable partner that delivered the project on time avoiding additional costs.
  • A water treatment system solution that fueled operational flexibility through evaporative cooling on the gas turbines and additional duct firing on the heat recovery steam generators that also contributed to higher flexibility.
  • Delivering a water treatment plant that minimizes environmental impact by recycling & treating cooling water which ensures low water consumption and that no contaminants reach local waterways after use.
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