1. Introduction
Guodian Ningxia Shizuishan Electric Power Company is a 2000 megawatt (MW) coal-fired power plant in Ningxia Hui Autonomous Region, China. The six power generation units and their water treatment systems were brought online between 2002 and 2006.
Reverse osmosis systems had been installed in order to produce high quality boiler feed water for the power generation while utilizing different feed water sources including recycling of waste water and RO concentrate.
The RO systems are operated on different feed water sources:
- blend of river water and ground water : 2 x 60 m3/hr permeate
- ground water: 3 x 70 m3/hr permeate
- process water: 4 x 90 m3/hr permeate
- blend of processs water (incl. boiler/cooling tower blowdown), RO concentrate and waste water: 6 x 147 m3/hr permeate.
2. Challenge
Since start-up Ochemate has been providing the water treatment chemicals and service support for the water treatment systems since the start-up of the system.
The raw feed water quality of the waste/process water is a challenge for the water treatment systems as it has a high organic fouling, a high biofouling and a high scaling potential in addition to composition changes/fluctuations.
The other water treatment systems have less fouling challenges.
In 2016, the client implemented changes in the operation of the power plant which resulted in a process water composition change: the calcium concentration increased 985 mg/l and the sulphate concentration increased 5900 mg/l.
3. Solution
Ochemate analyzed different process water samples and carried out scaling projections and scaling tests in order to determine whether the current antiscalant CPE6000 would be still effective for the systems operating on process water or process water blends.
4. Conclusions
The antiscalant CPE6000 is effective in preventing calcium sulphate scaling in the RO systems operating on process water or process water blends.
The water treatment chemicals and the services provided by Ochemate allow the client to minimize the operating expenses of the water treatment systems.
The cleaning frequency of the RO systems is every 12 to 18 months.
The membrane life is 9 years which is extremely high as the typical membrane life is between 3 and 5 years.
