With the domestic unit parameters and capacity, the thermal power unit is continuously improved and the scale is expanded. Chemical water treatment in power plants has also caused great difficulties.
The chemical water treatment plant has a corresponding plan in terms of technical methods, equipment layout, process control monitoring, operation and maintenance, and production management.
1. Boiler feed water treatment
Conventional boiler feed water pretreatment is usually a coagulation filtration process. Large thermal power plants clarify processing equipment, mainly mechanical acceleration clarifier mixing. The advantages are a fast response, easy operation control, and large output.
In recent years, frequency conversion technology has been continuously applied to the solidification process to further improve the pretreatment of water quality and reduce manual operations. During the development of the filter, the granular media filtration technology material has undergone a development stage from a slow filter to fast filtration speed and multi-media filter. This has played a role in improving water quality pretreatment.
However, due to the limitation of particulate materials, water filtration equipment, interception capability and filtration speed are greatly limited.
Boiler feed water desalination pretreatment technology, reverse osmosis technology (RO) has become a bright spot. The biggest feature of reverse osmosis is that it is not affected by changes in the quality of raw water.
Reverse osmosis has the ability to remove organic matter and remove silicon. Meet the stringent requirements of large equipment for the content of silicone in water.
Because reverse osmosis removes most of the ionic water (typically about 90%) to reduce the burden on the next step in a desalting ion exchange system. It thus reduces acid and alkali waste emissions. Reducing the salt content of wastewater discharges increases the benefits of economic and environmental plants.
In the demineralization of boiler feed water, mixed bed still plays an irreplaceable role. The development of the mixed bed itself is mainly reflected in two aspects: environmental protection and energy saving.
2. Boiler water treatment
The phosphating furnace technology has been in existence for more than 70 years and now has 70% of the world’s use of furnace drum phosphate boiler water treatment.
Due to the low boiler parameters in the past, boiler water often has a large amount of calcium and magnesium ions. In order to prevent boiler fouling, a large amount of phosphate is added to the boiler water.
Therefore, the pH value of the water furnace is very high, and the problem of alkaline corrosion is particularly prominent.
In this case, coordinated phosphating treatment came into being and achieved a certain anti-corrosion effect. However, with the boiler parameters continue to increase, the phenomenon of “hidden” phosphonates is becoming more and more serious, leading to more and more acid corrosion.
On the other hand, the high parameters of the boiler feedwater system have been used in desalination and condensation polishing systems. Therefore, there is no hardness component of the basic boiler water and the phosphonate treatment. In addition to the main role of preservatives from hardness to pH adjustment.
3. Condensate treatment
At present, most units of 300 MW and above are equipped with high-parameter condensate polishing equipment. However, there are not many real long-running operations for ammonia processing of fine processing equipment.
From an environmental point of view and an economic point of view, to achieve ammoniation operation will be the development direction of future precision processing systems.
In addition, investments in equipment, equipment layout, and process optimization should be considered as far as possible using existing power plant utility systems. Such as reducing the resin regeneration fan and the recirculation pump mixed bed.
As a program-controlled device system, it is installed in the boiler water supply side regeneration device to facilitate centralized management.
4. Circulating water treatment
In thermal power plants with closed circulation cooling, the recycling of cooling water and the stability of water quality are the focus of water treatment. In order to avoid the secondary pollution of the phosphorus-based water treatment agent to the environmental water body, the high-efficiency scale inhibitor dispersant and the multi-copolymer water treatment agent of the low phosphorus and non-phosphorus formula are gradually applied.
Thermal power plants that use open-cycle cooling, especially coastal power plants that use seawater as cooling water, are typically treated with chlorination. However, some power plants use electrolyzed seawater to produce sodium hypochlorite as a fungicide.
5. Sewage treatment
At present, large industrial sewage treatment plants adopt the basic mode of centralized sewage collection and treatment steps. In recent years, two-phase flow of solid-liquid separation technology has been gradually applied.
The technology employs a process of coagulation, flocculation, sedimentation, clarification, scraping, scumming, and sludge concentration. So the sediment, suspended matter, algae, solid suspended matter and oil in the water in the same facility are separated.
This treatment technology improves the quality of water, reduces processing costs, and expands the scope of recycling.