Method and equipment for NMP recovery and heat-pump rectification in lithium electric production

Abstract

The invention provides a method and equipment for NMP recovery and heat-pump rectification of in lithium electric production. The method comprises the following steps that NMP waste gas is absorbed byusing water so as to obtain NMP waste liquid; the NMP waste liquid is conveyed to a first dewatering rectifying tower for separation; heavy components extracted from a tower kettle of the first dewatering rectifying tower are conveyed to a second dewatering rectifying tower for separation; and heavy components extracted from a tower kettle of the second dewatering rectifying tower are conveyed toan NMP rectifying tower for separation, overhead light component gas of the first dewatering rectifying tower is further pressurized and heated to be high-pressure saturated steam through a compressor, and the high-pressure saturated steam serves as a heat source of a reboiler of a tower kettle of the NMP rectifying tower. According to the method, the volatile NMP waste gas in lithium battery production can be recovered and purified so as to obtain the electronic-grade NMP solvent, the electronic-grade NMP solvent can be directly used as a solvent for anode and cathode materials in lithium battery production, and the NMP utilization degree is high; and a rectification technology is coupled with a heat pump technology, heat energy of overhead steam of a rectifying device is converted intohigh-grade heat energy from low-grade heat energy, the high-grade heat energy is used as the heat source of the reboiler of the tower kettle, so that the energy of the waste gas in the equipment is fully utilized, and the overall energy consumption of the equipment is reduced.

Description

technical field [0001] The invention belongs to the technical field of lithium battery production, and in particular relates to a method and equipment for NMP recovery heat pump rectification in lithium battery production. Background technique [0002] N-Methylpyrrolidone, the English name N-Methylpyrrolidone, namely NMP, is an important chemical raw material, a polar solvent with strong selectivity and good stability, and a solvent commonly used in the production process of lithium batteries. In the battery production process, NMP is often used as a solvent when making lithium battery positive and negative electrode materials and lithium battery separators. In the production process, with the production of lithium battery positive and negative electrode materials and separators, the NMP solvent used continues to volatilize. Usually in the production process, the volatilized NMP will be sucked away, absorbed and then discharged, which will cause a serious waste of NMP raw ma...

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Problems solved by technology

[0002] N-Methylpyrrolidone, the English name N-Methylpyrrolidone, namely NMP, is an important chemical raw material, a polar solvent with strong selectivity and good stability, and a solvent commonly used in the production process of lithium batteries. In the battery production process, NMP is often used as a solvent when making lithium battery positive and negative electrode materials and lithium battery separators. In the production process, with the production of lithium battery positive and negative electrode materials and separators, the NMP solvent used continues to volatilize. Usually in the production process, the volatilized NMP will be sucked away, absorbed and then discharged, which will cause a serious waste of NMP raw materials and also cause environmental pollution. Therefore, it is necessary to recycle the volatilized NMP gas to improve NMP. However, when preparing electrode materials, a part of heavy impurity compounds, metal ions, free amines, etc. will be taken out with the volatilization of the solvent, and the purity of recovered NMP is very low, and there are absorbents, heavy Impurities such as heterocompounds, metal ions, and free amines make the recovered NMP unable to be directly used as a solvent for reuse, and the separation and purification of the recovered NMP will inevitably result in a large amount of energy consumption. Therefore, how to optimize the production process of lithium batteries Effective recovery and separation of volatile and wasted NMP in the medium to obtain NMP that can be directly used as a solvent for lithium battery production, and reducing the energy consumption required for recovery and separation are currently technical problems that need to be solved

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