Discuss the significance of zero-discharge treatment process for desulfurization wastewater from coal-fired power plants
In my country, power generation still mainly relies on thermal power generation, which is also one of the important guarantees for my country’s economic development.
In addition, although coal-based thermal power plants provide stable power resources for our country, various pollutants, mainly sulfur dioxide, produced in the process of power generation also bring a serious burden to the environment.
The purpose of discussing the zero-discharge treatment process of desulfurization wastewater from coal-fired power plants is to fundamentally solve the problem of pollutant discharge in thermal power plants. The development of this work has far-reaching significance for the healthy development of the power industry.
Overview of desulfurization wastewater from coal-fired power plants
2.1 The production route of desulfurization wastewater
Judging from the status quo of power plants in recent years, major coal-fired power plants are sparing no effort in technological exploration.
However, no effective solution has been found, and the traditional process is still the limestone-gypsum wet method.
This desulfurization method is very simple. It mainly treats the sulfur dioxide in the flue gas in the coal combustion furnace. Compared with other processes, this process has a good effect.
However, the disadvantage is that a large amount of waste water will be produced in the treatment process, and it has a variety of heavy metals, so it will also produce secondary pollution, which is the source of desulfurization waste water.
2.2 Characteristics of desulfurization wastewater
First, desulfurization wastewater is very corrosive.
In general, this kind of wastewater contains a large amount of strong acid and weak alkali salts and industrial waste acid, although the concentration is not very large, but this makes it highly corrosive.
These acidic substances will not only have a serious impact on the environment, but also cause serious damage to the mechanical equipment of the power plant; secondly, the desulfurization wastewater has a relatively high salt content, which is affected by the chemicals in the waste liquid, especially in the waste liquid. The presence of a large number of strong acid and weak base salts has a greater impact on the process.
According to the statistics of the power plant, the salt content in the waste water of the power plant is 30,000 mg per liter, which is a very considerable value compared with other waste water; finally, the hardness of the desulfurization waste water is relatively high, and it is very easy to scale.
Industrial desulfurization wastewater contains a large amount of calcium ions and magnesium ions in free state, which are very unstable, especially sensitive to temperature. When the temperature rises, these calcium and magnesium ions will crystallize, that is, scaling.
At the same time, these high content of calcium and magnesium ions make the desulfurization wastewater have strong hardness, which will cause serious damage to power plant equipment and desulfurization equipment.
Discussion on zero discharge treatment process of desulfurization wastewater from coal-fired power plants
3.1 High-efficiency reverse osmosis technology
The so-called high-efficiency reverse osmosis technology is a technology for treating wastewater with the help of some special reverse osmosis brine, which is mainly improved on the traditional technology.
Taking advantage of the principle of ion exchange in chemical reactions, silicon ions will not be reacted by reverse osmosis mode, and organic matter will undergo saponification reaction at higher pH, the upgraded high-efficiency reverse osmosis technology can efficiently remove various kinds of desulfurization wastewater. Organic pollutants, salt chemicals, and various scaling substances.
However, this technology usually requires some special reverse osmosis brine, and the intermediate process is complicated, so the practicability of the process needs to be improved.
At present, the most commonly used treatment method in the industry is that pretreatment and membrane concentration are integrated together. The actual operation process is to use a variety of economical methods to further concentrate the concentrated brine until the TDS mass concentration of the wastewater reaches the range of 50,000 to 80,000 mg/L. within.
Through this method, the scale of the subsequent evaporator is minimized, so as to reduce the initial capital investment, and effectively improve the economy and economy of the process.
3.2 Advanced Oxidation Technology
With the continuous improvement of the complexity of power plant wastewater, especially the increasing complexity of organic matter, coupled with the continuous improvement of environmental protection requirements, in this situation, advanced oxidation technology has been effectively developed.
Since then, many new oxidation technologies have been continuously applied in advanced oxidation technology, making oxidation technology more ideal.
Among the latest oxidation technologies are:
Photochemical oxidation, ozone oxidation, catalytic humidification oxidation, Fenton method, etc. This advanced oxidation technology uses special oxidants to prepare hydroxyl radicals with advanced flower-growing properties. degradation, so as to achieve the purpose of purifying water.
3.3 Multi-effect crystallization evaporation
This kind of treatment process is similar to the first two, and both require a certain pretreatment of wastewater in the early stage, and then carry out comprehensive treatment.
The multi-effect evaporation process is mainly divided into four major sections, the specific details are as follows:
The pretreated wastewater is still in a high temperature state, at this time it can be directly sent to the multi-effect evaporation system; after the gradual heating is completed, it can be added to the magma bucket;
After that, the wastewater will be sent to a salt cyclone for crystallization, and the crystals precipitated in the wastewater will be separated by a centrifuge; finally, it will be transferred to a drying bed for drying, so that the salt and other substances in the wastewater are separated.
To sum up, although my country’s power industry has achieved rapid development in recent years, various new forms of power generation are constantly being applied.
However, from the perspective of the layout of the entire power industry, coal-based thermal power plants are still the main form of power generation in my country, and in this process, some pollution is inevitably generated.
The discussion on the zero-discharge treatment process of desulfurization wastewater from coal-fired power plants is to solve the pollution problems generated in the above process. I hope this paper can provide some help for researchers in related fields.