Electric power has always been the main clean energy source for economic construction and urban development, and it has attracted much attention. At present, electric power is mostly generated by the combustion of fossil fuels except for a small number of other new energy sources. Therefore, the stable operation of large generator sets and related equipment has become a guarantee for the normal operation of electric power production.
With the increase in the production efficiency and other functions of such large generator sets and corresponding equipment, the standards for the water quality used are becoming more stringent.
1. The Characteristics & Situation of Chemical Water Treatment in Power Plants
1.1 Equipment Layout Shifts from Decentralization to Centralization
The layout of equipment in traditional power plants is mainly in a unitized and decentralized state according to its use. This arrangement lacks the effective and reasonable use of space and wastes resources too much. Moreover, the long pipeline line causes excessive energy consumption during the transportation process. These are not conducive to actual production and management needs. Nowadays, all kinds of factory layouts are gradually developing in three dimensions. Equipment is centrally arranged. This not only saves space but also increases the utilization of the equipment.
1.2 Production Monitoring Gradually Develops Towards Centralization, Automation & Intelligence
Traditional chemical water treatment systems usually use human-based on-site monitoring to achieve day-to-day management of the production site. Unnecessary accidents caused by human operation delays. With the development of remote control, automation and computer technology, programmable logic controllers (PLCs) are widely used. Using PLC to realize data acquisition and control of each device.
The chemical water treatment system enables centralized monitoring, operation, and control. The emergency response of the emergency situation is realized through the chain control.
1.3 Water Resources Basically Achieve Zero-emission Comprehensive Utilization
Power plant water consumption is severe in actual production. In order to respond to environmental requirements, water resources must be used effectively. At present, some power plants with a higher degree of automation have basically achieved zero discharge of wastewater. This not only achieves the purpose of saving water but also avoids environmental pollution.
1.4 Power Plant Chemical Water Treatment New Technology Is Continuously Used
Common processes for chemical water treatment in traditional power plants include filtration and sedimentation, dosing and concentration, etc. These water treatment methods are relatively backward. As technology advances, some new water treatment technologies are applied to power plants. Such as ion membrane, ultrafiltration, reverse osmosis, and other technologies. These new technologies provide effective technical support for chemical water treatment in power plants.
1.5 Process Detection Control Is Gradually Improved & The Test Results Are More Accurate
With the advancement of technology, various online detection technologies and detection accuracy have been developed and improved. This guarantees the online monitoring of the chemical water treatment system of the power plant. This is conducive to the prevention of water quality beforehand. It effectively ensures the long-term normal operation of the equipment.
2. Application & Development of New Chemical Water Treatment Technology in Power Plants
2.1 Traditional Chemical Water Treatment Technology of Power Plants
The purpose of chemical water treatment in power plants is to prevent equipment fouling and corrosion. At present, the commonly used chemical water treatment methods mainly include an ion resin exchange method. Therefore, there are more ionic resin exchange tanks in the chemical water treatment plant of the power plant. And by continuously switching, the ionic resin is continuously regenerated.
Common chemical water treatment methods are as follows. The tap water is boosted by a booster pump and enters the filter to filter out large particles of impurities. After passing through the ion resin exchanger, it enters the desalinated water tank, and the power plant boiler and equipment are used.
2.2 Application and Development Prospects of Membrane Separation Technology in Power Plants
With the development of technology, membrane separation technology has been widely used in power plant chemical water treatment systems. Membrane separation technology mainly relies on some high-performance polymer microporous materials to achieve filtration and purification of tiny impurities in water. So far, membrane separation technology mainly includes microfiltration, ultrafiltration and reverse osmosis. It has achieved significant results in chemical water treatment in power plants.
Both microfiltration and ultrafiltration techniques selectively separate materials through the microporous structure on the surface of the membrane. While the reverse osmosis technology mainly uses the pressure difference on both sides of the membrane as a driving force to separate the solvent from the solution. At present, reverse osmosis technology is the most widely used and environmentally friendly technology in membrane separation technology. Reverse osmosis technology mainly isolates impurities and other substances through a semi-permeable membrane, and its main components are membrane modules.
Pressurized water is pressed from one end of the membrane module during operation. The chemical substance in the water enters the diversion layer through the semi-permeable membrane and is discharged along the channel through the central hole of the membrane module. The water quality treated by this method is good. It is highly concerned by the power plant.
2.3 Power Plant Equipment Supply Water Method Anti-corrosion Treatment Application and Development
The problem of boiler corrosion protection has always been a key issue in power plant production. In the process of water replenishment of boilers, equipment corrosion is often caused by unqualified water, which affects the normal use of equipment. In serious cases, production accidents such as explosions may occur. At present, the methods of deoxidizing and preserving water mainly include physical methods and chemical methods.
Using physical thermal deaeration technology to reduce the oxygen content in water by heating the boiler feed water to boiling point. This method is relatively simple to operate but has shortcomings such as easy vaporization and high energy consumption. The vacuum deaeration technology is used for boilers with poor thermal deoxidation effect, and a satisfactory oxygen removal effect can be obtained.
Commonly used chemical deoxidation and anti-corrosion technologies mainly include sodium sulfite deoxidation, resin deoxidation, etc. They all achieve better oxygen-scavenging effects. The main principle of using sodium sulfite to remove oxygen is as follows:
2NaSo3 + O2 → 2Na2So4
At the same time, the oxygenation in the boiler feedwater can be effectively increased by electrochemical means. This promotes the passivation of the boiler metal surface and forms an oxide film on the surface. Thereby playing the purpose of anti-corrosion.
At present, the main wastewater of the power plant is basically discharged by pretreatment after chemical treatment. This is easy to cause local water and soil pollution. Moreover, the phosphate used in the chemical treatment causes eutrophication of the water body. This seriously jeopardizes the local aquatic environment. With the increasing emphasis on environmental issues, power plants should take certain measures to achieve zero or green emissions of wastewater.
First, the power plant should analyze the properties of the substances added in the chemical water treatment according to the actual situation. The power plant adopts an appropriate method to neutralize and achieve zero pollution discharge.
Second, power plants should use advanced technology to change boiler water and water treatment methods.
Solve the problem of water pollution from the source.