1. Policy tightening, new coal chemical projects need to achieve zero discharge
Coal chemical industry is using coal as raw material, through chemical processing to make coal into gas, liquid, solid fuel and chemical process. Coal chemical industry classification of traditional coal chemical industry and new coal chemical industry. Traditional coal chemical industry is divided into synthetic ammonia, urea, methanol, methanol, acetic acid, calcium carbide, acetylene derivatives, etc.; new coal chemical industry includes coal to oil, coal to natural gas, coal to olefin, coal to dimethyl ether, etc. New coal chemical project production and construction of ecological environment and energy coordinated development as the main melody, but the new coal chemical industry is high water consumption, water consumption and wastewater emissions is relatively high, the current China coal chemical project produce about 117 million tons of wastewater every year, coal oil, coal to olefin and coal gas unit product average water consumption of 10,27,6 t respectively, so the project is usually distributed in rich coal resources and water resources. Therefore, the overuse and destruction of water resources is considered to be the most serious environmental problem faced by the coal chemical industry.
The state has also further tightened the wastewater discharge policy for new coal chemical projects, requiring the wastewater reuse rate to be above 95% and finally meet the "zero discharge" standard.
The treatment process of the end of coal chemical wastewater mainly includes the following steps: the high mixed salt liquor is discharged from the front evaporation crystallization system to the storage tank to a drying equipment through the pump; the mixed salt liquor is continuously heated by the heating medium (water steam or hot air), the moisture in the inorganic salt and other impurities; the secondary steam emitted by the flash is absorbed through the exhaust gas absorption device, and the exhaust gas is qualified. At present, the common traditional drying equipment on the market are drum scraper dryer, rake dryer, single steam kettle, spray tower dryer and scraper film evaporator.
2. Introduction to common traditional waste water drying equipment
2.1 Drum scraper dryer
The drum scraper dryer is a drying equipment attached to the rotary cylinder in the form of heat conduction. The material liquid and the cloth device form the material film on the outer wall of the drum rotating at a certain rotation speed, which is heated by the hot drum wall of the heating medium (water steam or thermal oil), and the material film is dried and scraped down by the scraper.
2.2 Rake-type dryer
Vacuum rake dryer is a novel horizontal intermittent vacuum drying equipment, wet material through conduction evaporation, with the scraper mixer constantly remove the material on the hot surface, and form a circulating flow in the container, the water evaporation by the vacuum pump. Vacuum rake dryer is used more in the organic semi-finished products and fuel drying operation in the chemical industry.
2.3 Single steamer
When the solution evaporates in the evaporator, the secondary steam produced by it is no longer used, and the solution is no longer concentrated into the second evaporator, that is, only one evaporator is used to complete the evaporation operation, which is called single-effect evaporation. The evaporation equipment using a single evaporation kettle is a single steam kettle.
2.4 Spray Dryer
Spray dryer is a method of systematic technology applied to material drying. After the atomization in the drying room, in contact with the hot air, the water quickly vaporizes, that is, the dry product. This method can directly make the solution, emulsion dry into powder or granular products, can save evaporation, crushing and other processes.
2.5 Scraper thin film evaporator
The scraper film evaporator is a heated steam jacket outside the shell, which is equipped with a rotating scraper inside, which is driven by the rotating shaft in the center of the cylinder. After the raw material liquid is added tangentially from the upper part of the evaporator, under the drive of gravity and rotating scraper, a thin film is formed along the inner wall of the shell. The finished liquid is discharged from the bottom, and the secondary steam is discharged from the upper part after the foam remover.
At present, these traditional drying equipment is not well applied in the industry, which cannot solve the demand pain point of mixed salt mother liquor drying, and brings new operation problems to operating customers, such as: unable to dry; high equipment failure rate, easy to paralysis; frequent cleaning, poor on-site sanitary environment; and the overall disposal efficiency is low. Related market research results show that the operation volume of equipment is only less than 30% of the design volume. Has brought great trouble to the customers. Energy consumption is generally high, the degree of automation is not high, and the human intervention is more. This is for the current comprehensive realization of "intelligent operation" and "intelligent factory" coal chemical industry, is undoubtedly unmatched.
Therefore, it is the expectation of all the zero discharge system of coal chemical wastewater to seek a solution of "high efficiency, intelligent" and thoroughly dry " of coal chemical wastewater.
3. WSD environmental protection skid-mounted mother liquid drying device
In order to solve the problem of zero discharge of mixed salt wastewater in coal chemical industry, WSD Environmental Protection has devoted itself to many years of research and innovation, and developed an efficient and stable skid-mounted low temperature steam crystallization device. Taking the daily treatment of 5000L high concentrated mixed salt mother liquid as an example, the following is the comparison between the traditional drying equipment and the new low temperature steam crystallization:
Characteristics of the mother liquid drying device
The device is skid-mounted and modular design, which can realize the drying of miscellaneous salt mother liquor to the greatest extent, and the effluent effect is good, no waste gas pollution, thermal pollution and other phenomena. At the same time, the system is automatic control, with the characteristics of automatic discharge, automatic cleaning, equipment cloud platform management and so on.
Before purification
Operating conditions of the unit: The temperature of the bearing bushes fluctuates, and the fluctuations intensify after filling about 300 liters of a foreign brand of dissolved oil. After each peak, the temperature drops, and then rises alternately, repeatedly tripping, causing the unit to fail to operate normally.
Flow chart of WSD mother liquor drying process
▲ engineering flow sheet
WSD environmental protection coal chemical wastewater "zero discharge" solution flow chart
In mid-December 2018, our company's varnish removal unit was selected. The equipment was put into use for less than 24 hours, and the phenomenon of temperature fluctuations was alleviated. The temperature dropped to about 85°C in less than a month, and the temperature of the equipment has been stable so far. The operation has been kept at around 80°C, which has solved the major problems of customers. In August 2019, the customer put into use our two sets varnish removal unit again on the other two main units.
typical case
The customer is the national energy and chemical industry base key scale enterprises. The MVR equipment of the original design evaporation crystallization device has no spare system, and the mother liquid drying process is not designed, which leads to the continuous circulation of mother liquid in the mother liquid in the system, resulting in the enrichment of pollutants and the mother liquid cannot be effectively treated. Customer new skid-mounted parent liquor drying device (processing capacity of 70 tons / day), the low temperature steam crystallization process, used to process coal chemical industry MVR evaporation crystallization system of foreign salt parent liquor, not only effectively solve the customer zero emission process terminal technology bottleneck problem, also for the local environmental protection, water saving and sustainable development is of great significance. WSD environmental protection helps customers to solve the problem of terminal treatment of high salt wastewater, get solid crystalline salt, and realize the real terminal zero discharge of high salt wastewater in coal chemical industry.
Kunshan WSD Environmental Protection Equipment Co., Ltd. was established in 2009, is a high-tech enterprise in Jiangsu Province, wastewater evaporator engineering technology research center, helping enterprises to open the "last kilometer" of zero wastewater discharge.
With years of research and development and innovation, it has more than 150 authorized patents, specializing in the treatment of coal chemical industry, fine chemical industry, fine chemical industry and hazardous waste, 600 + national classic cases, a cumulative equipment operation capacity of 961,884 tons / year, and a managed disposal and operation capacity of 100,000 tons / year.
Closely around customer needs, WSD can provide customers with customized wastewater treatment services, including working condition investigation, media analysis, pre-sales technical support, research and development, manufacturing, installation, commissioning, delivery, after-sales support to continuous tracking of the whole chain comprehensive service system.
Post time: Sep-27-2023