I. Preface
1. N-methyl pyrrolidone is an important chemical raw material, which is widely used in petroleum processing, fine chemical industry, pharmaceuticals, pesticides, electronic products and other fields. It plays an important role in the chemical industry and is one of the indispensable raw materials for lithium battery manufacturing. The Pearl River Delta region is the production of lithium batteries in China and even in the world. The base needs to consume a large amount of N-methyl pyrrolidone, and the used N-methyl pyrrolidone will be discharged into the atmosphere in the form of organic waste gas, which not only causes great pollution to the local environment, but also causes huge economic losses and energy waste. Therefore, according to the national energy, environmental protection and other development strategies, our company has organized the research and development of the "lithium battery factory organic waste gas recovery technology" and its set of equipment, which has solved this difficult problem for lithium battery factory. At present, our N-methyl pyrrolidone solvent recovery equipment has been industrialized. Advanced technology and excellent after-sales service have enabled our company to have a large number of customers in the domestic market.
2. N-methyl pyrrolidone is a wide range of highly efficient polar solvents. It can dissolve with water at room temperature and boil at 202 under atmospheric pressure. According to the unique physical characteristics of nmp, our company uses low-energy refrigeration and condensation methods, through special process design, to produce a complete set of equipment for efficient recovery of organic waste gas NMP. This complete set of equipment is widely used in NMP recovery of the exhaust gas from coating machine in lithium battery factory. It can not only reduce the discharge of organic matter, but also obtain considerable economic benefits.
2. Process characteristics of recovery unit
1. Relatively independent one-to-one recovery device ensures the recovery efficiency of NMP and smooth operation of coating machine. According to our successful experience, each coating machine is equipped with an independent NMP recovery device, which has the simplest operation and management, the highest recovery efficiency and the best energy saving effect.
2. Improve the stability and safety of the recovery device and refrigeration system.
3. High degree of automation: automatic control system and interlocking system are designed for each recovery device, which can ensure the safe production and smooth operation of coating machine and recovery device.
4. Unique equipment selection, equipment manufacturing, equipment installation methods and optimized process flow have eliminated the common phenomena of running, falling, dripping and leaking in general NMP recovery devices.
5. Emission standard can be less than 300 ppm.
6. The recovery rate of the device is more than 90% when the length of the pipeline is less than 15 meters and the concentration of the recovery solution is more than 80%
7. The power of each unit is about 3-5 kw.
3. Main technological parameters
Waste gas treatment capacity
Waste solvent recovery
Minimum solvent recovery
VOC concentration of exhaust gas < br /> WF5000 Series
5000Nm3/h < br />. 15kg/h
90% or more < br />. Less than 300 ppm < br /> Name
Specification of recovery unit
Induced Draft Fan
Cooling Tower
Circulating water pump < br /> Cold water pump
Waste liquid storage system
Synthetic filtration system
Total power consumption
WF5000
2000X900X1000
30t < br /> 1.5Kw
1.5 kW < br /> 2m < br /> About 3Kw < br />. Description: The data listed in the table are for reference only, and the specific data are based on the final manufacturing results.
4. Composition of main body components of recovery unit and related instructions
Serial number < br /> Name
Precooler < br /> Front cooler
Rear cooler < br /> Type 1 < br /> Shell and tube heat exchanger < br /> Finned tube heat exchanger
Finned tube heat exchanger
2. Material of recycling box < br />. 304 Material
Aluminum
Aluminum
3. Heat transfer area < br />. About 14 M2 < br /> 7m2 < br /> 7m2 < br /> 4 pipeline medium < br /> Hot exhaust gas < br /> Circulating water
Circulating water
5 shell-side medium < br /> Cold exhaust < br /> Hot exhaust gas < br /> Hot exhaust gas < br /> 6 Working Principle
After passing through the rear cooler, the temperature drops to about 20 C, so it can be used to pre-cool the hot exhaust gas from the coating machine into the recovery device, so that the second cooling of the hot exhaust gas can be achieved, and the last recovery of NMP can be realized in the shell side.
Using circulating water to reduce the temperature of heat waste gas, the third stage cooling of heat waste gas is realized and part of NMP is recovered.
The circulating water flow rate is about 8 tons/hour, the inlet temperature of the circulating water is 30 C, and the outlet temperature is not higher than 40 C. If the recovery unit uses air-cooled refrigeration units (without cooling towers), the circulating water in this temperature range needs to be allocated with the return water of the ground temperature water and the rear cooler.
By using the low temperature water of about 10 C made by the recovery device, the fourth stage cooling of the hot exhaust gas can be realized and most of the NMP can be recovered.
The low-temperature water circulation is about 8 tons/hour. The temperature is set by the outlet temperature of the induced draft fan. Generally, the setting value is between 20 and 30 degrees C, depending on the recovery effect.
5. Process flow chart of recovery unit
Process description:
1. The heat exhaust gas in the coating machine is fully exchanged through the heat exchanger, and the fresh air temperature is raised by 30-50 degrees (depending on the coating machine) and then sent back to the coating machine, which saves a lot of energy consumption.
2. After heat exchange, the exhaust gas is cooled in the first stage and sent to the first cooler for condensation and recovery, and then to the second condenser for recovery.
3. After the second recovery, the exhaust gas is filtered through the purifier to realize the third recovery, which is discharged outdoors through the fan.
4. The internal structure of the recycling system adopts new materials and new technology, which greatly improves the recovery rate, service life and reliability of the equipment. The air duct of the equipment is connected by 304 stainless steel flanges to eliminate drip leakage.
Through the above process, the recovery system