Waste gas and waste liquid treatment system in waste lithium battery recovery treatment process

Abstract

The utility model discloses a waste gas and waste liquid treatment system in a waste lithium battery recycling process. The system comprises a waste gas introduction and pretreatment unit, an organic waste liquid introduction unit, a direct-fired incineration unit, a flue gas purification and waste heat recovery unit and a washing wastewater treatment and reuse unit. Waste gas from multiple sources is pretreated and then enters a direct combustion furnace together with collected organic waste liquid for collaborative incineration; the incineration flue gas is subjected to temperature reduction, secondary waste heat recovery, acid gas absorption and final purification and then is discharged after reaching the standard; generated washing wastewater is recycled after being treated. The device can efficiently remove VOCs and acid gas, full recovery of waste heat and zero discharge of waste water are achieved, and the device is good in anti-corrosion and anti-blocking performance, safe and economical in operation and low in secondary pollution.

Description

TECHNICAL FIELD

[0001] The utility model relates to waste battery recycling processing technical field especially relates to a waste gas waste liquid treatment system in waste lithium battery recycling processing. BACKGROUND

[0002] In the recycling process of waste lithium batteries, especially in the pyrolysis process, a large amount of organic waste gas and organic waste liquid with complex components and high pollutant concentration are generated. These pollutants mainly include carbonates, ketones, esters, ethers, hydrocarbons, and acidic substances containing fluorine and phosphorus. The existing treatment technology generally faces the following technical problems when dealing with such complex waste gas and waste liquid:

[0003] First, the treatment efficiency and stability are insufficient: Many traditional treatment methods, such as single adsorption, photolysis, or conventional catalytic oxidation, are difficult to achieve sustained and efficient purification for the complex components and high-concentration organic waste gas and corrosive gas (such as HF) generated by waste lithium batteries. The treatment effect fluctuates greatly, and it is difficult to ensure that the final emission meets the increasingly stringent environmental protection standards.

[0004] Second, high energy consumption and high operating cost: Traditional waste gas incineration treatment process often involves high energy consumption, especially in the absence of effective waste heat recovery mechanisms, resulting in high overall operating costs and poor economic efficiency.

[0005] Third, poor control of secondary pollutants: In the waste gas purification process, especially in the wet scrubbing process, a large amount of scrubbing wastewater containing harmful substances (such as fluorides and phosphates) is generated. Without effective treatment and reuse measures, it will cause secondary pollution of water bodies and increase the burden and cost of subsequent wastewater treatment.

[0006] Therefore, it is of great practical significance and application value to develop a comprehensive treatment technology that can efficiently and stably treat complex waste gas and waste liquid generated in the recycling process of waste lithium batteries, while achieving energy recovery and utilization, reducing operating costs, and effectively controlling secondary pollution. INVENTION CONTENTS

[0007] The utility model aims at solving the technical problems of insufficient treatment efficiency and stability, high energy consumption, high operating cost, and poor control of secondary pollutants in the existing technology when treating waste gas and waste liquid generated in the recycling process of waste lithium batteries.

[0008] To solve the above problems, the utility model provides a waste gas and waste liquid treatment system in the recycling process of waste lithium batteries, comprising:

[0009] At least one waste gas introduction and pretreatment unit is used to introduce and pretreat the waste gas containing target pollutants generated from the recycling process of waste lithium batteries;

[0010] an organic waste liquid introduction unit for introducing organic waste liquid generated in the recycling process of the waste lithium battery;

[0011] a direct combustion incineration unit configured with a combustion device capable of receiving and cooperatively incinerating the pretreated waste gas and the organic waste liquid, for oxidizing and decomposing the target pollutants and the organic waste liquid at high temperature;

[0012] a flue gas purification and waste heat recovery unit connected to the flue gas outlet of the direct combustion incineration unit, for cooling, waste heat recovery, acid gas absorption and final purification treatment of the high-temperature flue gas generated by incineration;

[0013] a washing wastewater treatment and recycling unit for treating washing wastewater generated in the flue gas purification process, and recycling the treated water to the flue gas purification and waste heat recovery unit.

[0014] Optionally, the at least one waste gas introduction and pretreatment unit comprises:

[0015] a first waste gas introduction and pretreatment branch for treating normal-temperature, oxygen-containing organic waste gas generated in the battery crushing workshop, the branch comprising a normal-temperature dust removal device and a first waste gas conveying device; and / or

[0016] a second waste gas introduction and pretreatment branch for treating high-temperature, anaerobic organic waste gas generated in the pyrolysis furnace, the branch comprising a high-temperature dust removal device and a second waste gas conveying device, the high-temperature dust removal device and its conveying pipeline being provided with high-temperature heat tracing and insulation measures.

[0017] Optionally, the organic waste liquid introduction unit comprises a liquid collection tank and a waste liquid conveying pump in communication with the conveying pipeline of the second waste gas introduction and pretreatment branch, for collecting and conveying the organic waste liquid condensed in the conveying pipeline to the direct combustion incineration unit.

[0018] Optionally, the combustion device of the direct combustion incineration unit is a mixed fuel low-nitrogen burner, and the hearth lining of the direct combustion incineration unit adopts a corrosion-resistant refractory material.

[0019] Optionally, the corrosion-resistant refractory material is chrome corundum castable.

[0020] Optionally, the flue gas purification and waste heat recovery unit comprises, in sequence:

[0021] a first waste heat recovery device for recovering steam from the heat of the high-temperature flue gas;

[0022] a flue gas quenching device for rapidly cooling the flue gas cooled by the first waste heat recovery device to a predetermined temperature to inhibit the generation of dioxins;

[0023] The acid gas absorption device is used for absorbing acid gas in flue gas, and a second waste heat recovery device is arranged on a circulating scrubbing liquid pipeline of the acid gas absorption device to recover flue gas waste heat to generate hot water.

[0024] The tail gas final purification device is used for adsorbing trace organic pollutants remaining in the flue gas.

[0025] Optionally, the first waste heat recovery device is a steam boiler, the second waste heat recovery device is a hot water heat exchanger, the acid gas absorption device comprises at least one alkali washing tower and a demister, and the tail gas final purification device is an activated carbon adsorption bed.

[0026] Optionally, the scrubbing wastewater treatment and recycling unit adopts a chemical precipitation method to treat the wastewater, so that target ions in the wastewater form precipitates, and the clear liquid after separation of the precipitates is recycled to the flue gas quenching device as a quenching water source.

[0027] According to the technical content disclosed by the utility model, the waste gas introduction and pretreatment unit, the organic waste liquid introduction unit, the direct combustion incineration unit, the flue gas purification and waste heat recovery unit and the scrubbing wastewater treatment and recycling unit are organically combined, and the following remarkable beneficial effects are brought about:

[0028] The pollutant treatment efficiency and stability are improved: the waste gas and the organic waste liquid after pretreatment are subjected to high-temperature synergistic incineration by the direct combustion incineration unit, and in combination with the multi-stage treatment of the subsequent flue gas purification unit, the complex organic pollutants and acidic substances in the waste gas and the waste liquid can be efficiently and completely decomposed, the stability of the treatment effect is ensured, and the compliance of the final emission is ensured, and the problems of insufficient treatment efficiency and poor stability in the prior art are effectively solved.

[0029] The energy consumption and operation cost are reduced: the design of the flue gas purification and waste heat recovery unit enables the heat energy in the high-temperature flue gas generated by direct combustion incineration to be effectively recovered and utilized in stages (for example, to generate steam and hot water), significantly reducing the dependence of the system on external energy, thereby reducing the overall operation cost and improving the economy.

[0030] Secondary pollution is effectively controlled and resource utilization is realized: the scrubbing wastewater treatment and recycling unit can effectively treat the scrubbing wastewater generated in the flue gas purification process, and the treated water is recycled to the flue gas purification and waste heat recovery unit (for example, as a quenching water source), realizing closed-loop circulation and zero emission of the wastewater, minimizing secondary water pollution, and saving water resources.

[0031] Other features and advantages of the utility model will become clear through the following detailed description of exemplary embodiments of the utility model with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0033] Figure 1 It is a process flow diagram of the waste gas and waste liquid treatment system in the waste old lithium battery recycling process of the present application.

[0034] Reference signs: 1, battery crushing waste gas inlet; 2, normal temperature dust remover; 3, normal temperature waste gas fan; 4, battery crushing waste gas pneumatic cut-off valve; 5, pyrolysis furnace waste gas inlet; 6, high temperature dust remover; 7, high temperature waste gas fan; 8, pyrolysis furnace waste gas pneumatic double cut-off valve; 9, emergency emptying valve; 10, natural gas inlet; 11, natural gas combustion-supporting fan; 12, direct-fired furnace; 13, mixed fuel low-nitrogen burner; 14, waste liquid spray gun; 15, high-temperature safety relief valve; 16, steam boiler; 17, steam outlet; 18, hot water outlet; 19, semi-dry quenching tower; 20, first-stage alkali washing tower; 21, hot water heat exchanger; 22, second-stage alkali washing tower; 23, demister; 24, activated carbon adsorption bed; 25, terminal induced draft fan; 26, chimney; 27, liquid collecting tank; 28, waste liquid booster pump; 29, waste liquid conveying pneumatic double cut-off valve; 30, waste water collecting tank; 31, reverse osmosis softener / water supply inlet; 32, mud cake; 33, filter press; 34, fire arrester; 35, manual double cut-off valve. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions, and values set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0036] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the application or its application or uses.

[0037] Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, techniques, methods, and devices should be considered as part of the description of the present application.

[0038] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary, and not as a limitation. Thus, other examples of exemplary embodiments can have different values.

[0039] It should be noted that like reference numerals and letters in the various figures indicate similar items, and thus, once any term is defined in one figure, it is not necessary to discuss it further in connection with other figures.

[0040] ReferringFigure 1 The waste gas waste liquid treatment system in the recycling process of the waste lithium battery mainly includes two waste gas feeding paths and one waste liquid feeding path, and finally converges into the core incineration and purification system.

[0041] The first waste gas feeding path processes the waste gas generated from the battery crushing workshop. The waste gas enters the system through the battery crushing waste gas inlet 1, first passes through the normal temperature dust remover 2 (such as a bag type dust remover or a filter cartridge type dust remover) to remove the dust particles entrained therein. The purified normal temperature waste gas is pressurized by the normal temperature waste gas fan 3, and is controlled by the battery crushing waste gas pneumatic cut-off valve 4, as part of the combustion air, and is safely and stably transported into the subsequent direct-fired furnace 12.

[0042] The second waste gas feeding path processes the high-temperature and high-concentration anaerobic organic waste gas generated from the pyrolysis furnace (not shown in the figure, as the main waste gas source). The waste gas enters the system through the pyrolysis furnace waste gas inlet 5, first enters the high-temperature dust remover 6 (such as a high-temperature filter bag dust remover or a ceramic fiber filter pipe), to remove the fine particulate matters such as black powder entrained in the waste gas. In order to prevent the waste gas from condensing to cause the filter material to dew and block during low-temperature start-up or intermittent operation, the high-temperature dust remover 6 can be configured with a nitrogen dehumidification heating device and / or an electromagnetic induction heating device, and nitrogen is preferably used for back-blowing dust removal. The connection pipeline from the pyrolysis furnace waste gas inlet 5 to the high-temperature dust remover 6, and to the subsequent direct-fired furnace 12, and the fire arrestor 34 provided on the pipeline, are all coated with an electric heating tape and wrapped with a thick heat insulation layer, to ensure that the inner wall temperature of the pipeline is maintained at a level not lower than 300 DEG C. This is aimed at effectively preventing the condensation and precipitation of the organic components with a higher boiling point in the waste gas. The purified high-temperature and high-concentration pyrolysis waste gas is drawn by the high-temperature waste gas fan 7 (usually a high-temperature and corrosion-resistant centrifugal fan), and is safely transported into the mixed fuel low-nitrogen burner 13 in the direct-fired furnace 12 after being controlled by the fire arrestor 34 and the pyrolysis furnace waste gas pneumatic double cut-off valve 8. In order to improve the reliability and stability of the system operation, the high-temperature dust remover 6, the fire arrestor 34 and the high-temperature waste gas fan 7 between the pyrolysis furnace waste gas outlet and the direct-fired furnace are preferably designed as one main and one standby, and the inlet and outlet of the standby device and the main device are provided with a manual double cut-off valve 35, to facilitate switching and maintenance. The waste gas pipeline is provided with a nitrogen purging interface, which is used for safe replacement before equipment switching or maintenance, to avoid leakage into oxygen when switching to the standby device. An emergency emptying valve 9 (preferably a pneumatic double cut-off valve) is provided on the main pipeline of the pyrolysis furnace waste gas, which is used to directly and safely discharge the pyrolysis furnace waste gas to a high altitude in abnormal conditions.

[0043] The waste liquid feed path processes a small amount of organic waste liquid that can be condensed in the high-temperature pipeline (especially the pyrolysis furnace waste gas conveying pipeline). These condensed liquids are collected in a collecting tank 27 provided at a lower position along the pipeline, which has a heat tracing and liquid level control function. The waste liquid in the collecting tank 27 is precisely metered by a corrosion-resistant waste liquid booster pump 28 and stably conveyed to a dedicated waste liquid lance 14 in the direct-fired furnace 12 through a waste liquid conveying pneumatic double shut-off valve 29 for atomized incineration treatment. This waste liquid lance is specially designed for processing high-viscosity organic waste liquid, and overcomes its viscous resistance through high pressure to smoothly spray and atomize it, forming a high-speed liquid stream at the nozzle, which produces strong shear with the surrounding air, breaks the waste liquid into fine droplets, realizes full mixing with air, and improves combustion efficiency. The spray angle and range of the waste liquid lance 14 can be adjusted according to the structure and combustion requirements of the direct-fired furnace 12.

[0044] The direct-fired furnace 12 is the core incineration unit of the system. Its furnace body can be designed as a vertical or horizontal cylindrical structure, and the outer shell is made of carbon steel material. The inner lining of the hearth is designed in a multi-layer composite structure, from inside to outside: the working layer uses special chromium corundum refractory castable with a Cr2O3 content of 12% to 15% (typical thickness of 150mm to 250mm), which can effectively resist chemical corrosion of acidic gases such as HF in the waste gas due to its excellent chemical stability and density; the intermediate layer is a lightweight insulating castable (typical thickness of 100mm to 200mm) for reducing heat loss; the outer layer is a silica alumina refractory fiber blanket or module (typical thickness of 100mm to 150mm) to further improve the insulation effect. This multi-layer structure design not only improves the corrosion resistance of the equipment, but also improves the overall thermal shock stability of the lining through the matching of the thermal expansion coefficients of the materials and the setting of the buffer layer, so that it is not easy to crack, peel off and other damage due to thermal stress under the working conditions of frequent start-stop or temperature fluctuations, ensuring the long-term stable operation of the direct-fired furnace. The design operating temperature range of the direct-fired furnace is usually 850°C to 1100°C, and the residence time of the flue gas in this high temperature range is ensured to be 2 to 3 seconds to achieve complete oxidation and decomposition of organic matter.

[0045] The mixed fuel low-NOx burner 13 is installed at one end of the direct-fired furnace and can support stable, efficient and low-NOx combustion of three fuels, namely natural gas, pyrolysis off-gas and organic waste liquid. Natural gas is introduced from the natural gas inlet 10 (LNG storage tank or other gas source) and supplied to the burner after being assisted by the natural gas combustion air fan 11 (if premix combustion is required). Natural gas is mainly used during the start-up and warming-up phase of the equipment, and the natural gas combustion air fan 11 is used to warm up and preheat the direct-fired furnace; when the flue gas temperature reaches, for example, 900°C or above, the system mainly relies on the combustion of off-gas and waste liquid to provide the necessary oxidation heat, at which time the supply of natural gas can be greatly reduced or even stopped; only when the off-gas or waste liquid heat value fluctuates greatly, causing unstable furnace temperature, will natural gas be combusted at the minimum flow required to maintain stable flame. To ensure that the combustion process proceeds stably, a flame holder (not separately marked) is provided at the outlet of each burner nozzle of the burner. To prevent accidental flameout, a standby flame (not separately marked) can be provided in the backflow area of the burner nozzle expansion, which can also serve as an ignition burner, using fuel gas (such as natural gas or LPG) and an electronic igniter to ignite. To achieve real-time monitoring of the combustion state, an ultraviolet flame detector (not separately marked) is arranged at the head of the burner for remote monitoring of the flame state. At the same time, to facilitate direct observation of the flame combustion by the operator, one or more viewing holes with high-temperature-resistant glass (not separately marked) can be provided on the precombustion chamber or the side wall of the furnace of the direct-fired furnace. The pyrolysis off-gas is introduced through a special passage of the burner (for example, using a cyclone vane structure to adapt to its low pressure and large flow characteristics). The organic waste liquid is sprayed into the burner through the waste liquid lance 14. The mixed fuel low-NOx burner 13 uses low-NOx combustion technology with staged air supply or staged fuel, the first stage is fuel-rich reducing atmosphere combustion, and the subsequent stages are supplemented with air to complete complete combustion. Part of the combustion air comes from the aforementioned treated battery breaking workshop off-gas, and the rest is supplied by a dedicated combustion air fan with fresh air. The direct-fired furnace 12 is provided with a high-temperature safety relief valve 15 at the top for overpressure protection.

[0046] The high-temperature flue gas (temperature about 1100°C) generated by the direct-fired furnace 12 first enters the steam boiler 16. Here, the high-temperature sensible heat of the flue gas is used to heat the feedwater, producing, for example, 1.0 MPaG, 184°C saturated steam, which is delivered to the plant steam pipe network or used for the system itself (such as the aforementioned direct-fired furnace over-temperature cooling). At the same time, a small amount of steam generated can also be used as a cooling medium when the direct-fired furnace is over-temperature, to avoid excessive fresh cold air from being introduced, resulting in increased natural gas consumption or excessive oxygen content fluctuations causing the converted pollutant emission concentration to exceed the standard. Preferably, the steam boiler is not provided with an economizer to maintain a relatively high flue gas outlet temperature, which is beneficial to the stable operation of the subsequent quenching unit. After the flue gas flows through the steam boiler 16, its temperature is significantly reduced to about 500°C.

[0047] The 500°C flue gas leaving the steam boiler 16 is immediately introduced into a semi-dry quench tower 19 (flue gas quenching device). The tower preferably adopts a counterflow semi-dry tower structure, and the inner lining thereof also adopts chromium corundum castable resistant to HF corrosion. The high-temperature flue gas is introduced from the top of the tower and uniformly dispersed in the tower through an internally arranged gas distribution device. At the same time, the treated and reused water from the subsequent wastewater treatment and reuse unit is transported to the several double-fluid atomizers (not separately marked) uniformly installed at the top or side of the tower through the quenching liquid pipeline, a quenching pump (not separately marked) and an electric regulating valve, and is sprayed into the tower in the form of extremely small liquid droplets. The quenching liquid directly contacts the high-temperature flue gas, absorbs a large amount of flue gas sensible heat through rapid evaporation of water, and rapidly reduces the flue gas temperature to below 200°C in 1.0 second, effectively avoiding the recombination temperature window of dioxins (250°C-450°C). The outlet temperature of the quenching tower and the consumption of the quenching liquid are automatically controlled through an automatic control system, the water injection amount is automatically adjusted, the quenching liquid is completely evaporated, the water vapor produced by the flue gas is carried into the next stage of treatment unit, and no liquid is accumulated at the bottom of the tower, and no sewage is produced.

[0048] The flue gas with a temperature reduced to below 200°C is introduced from the semi-dry quench tower 19 into an acid gas washing unit. First, a primary alkali washing tower 20 is provided. An automatic alkali liquid adding system is arranged in the tower, the pH value of the circulating spray liquid is monitored in real time through an online pH meter, and the supplement of alkali liquid (commonly NaOH solution) is automatically controlled to maintain the pH value of the circulating liquid in a preset alkaline range (for example, 8-10) to efficiently absorb the acid gases such as HF, HCI and SO2 in the flue gas. After the circulating spray liquid of the primary alkali washing tower 20 is collected in the tower kettle, part of it is transported back to the top of the tower by a circulating pump to continue spraying, and the other part flows through a hot water heat exchanger 21 arranged on the circulating pipeline thereof. Here, the flue gas residual heat absorbed by the circulating liquid is transferred to the softened water (or tap water after softened treatment) in the passage to heat the softened water to about 60°C-80°C, and the produced hot water is transported through the hot water outlet 18 to be used as preheated feed water of the steam boiler 16 or for other production processes such as heating and living in the factory area, so that the heat absorbed by the primary alkali washing tower is converted into useful heat energy, and further cascade recovery of heat energy is realized. The circulating alkali liquid after being cooled by the hot water heat exchanger 21 returns to the tower kettle.

[0049] After the flue gas leaves the primary alkali washing tower 20, it is immediately introduced into a secondary alkali washing tower 22 for more thorough deep purification of acid gases. The flue gas discharged from the secondary alkali washing tower 22 passes through a high-efficiency demister 23 (usually in the form of a combination of a wire mesh demister and a baffle plate demister) to effectively remove the fine alkali liquid droplets entrained in the flue gas.

[0050] The flue gas after the above multi-stage washing and mist removal treatment enters the deep purification unit of the system, i.e. the activated carbon adsorption bed 24. The adsorption bed adsorbs the possible residual trace VOCs and the possible trace dioxin substances generated or not completely removed in the incineration and quenching process, as the last safeguard measure to ensure that the gas discharged from the final exhaust cylinder completely meets the emission standard. The purified tail gas is drawn by the terminal induced draft fan 25 and discharged through the chimney 26 to meet the standard at high altitude.

[0051] The wastewater treatment and reuse unit is responsible for treating the washing wastewater generated by the entire system. The wastewater generated by the first alkali washing tower 20, the second alkali washing tower 22 and the mist remover 23 is uniformly collected into the wastewater collection tank 30. The pre-prepared lime milk is accurately added to the wastewater collection tank 30 through the calcium hydroxide / quicklime addition port, and is fully stirred and reacted. The Ca 2 ions in the quicklime react with F ions in the wastewater to form CaF2precipitate, and react with PO4 3- ions to form Ca3(PO4)2precipitate. The slurry after the reaction is sent to the filter press 33 for solid-liquid separation. The mud cake 32 generated by the filter press is treated as industrial solid waste, and is entrusted to a professional unit with corresponding qualifications for safe disposal. The clear liquid obtained by the filter press is collected in the clear liquid tank, and is used as a clean supplementary water source. After being pressurized by the reuse water pump, it is delivered to the aforementioned semi-dry quenching tower 19 as the circulating water for the quenching process, so as to realize the closed-loop circulation and zero discharge of the system process wastewater. The system is provided with a reverse osmosis soft water machine / water supplement inlet 31, which is used to supplement fresh water or prepare soft water to the system when necessary.

[0052] The operation of the entire waste gas and waste liquid treatment system is monitored and automatically operated by an automatic control unit (the core is PLC) not shown in detail in the figure, ensuring that the process parameters are stable and controllable, and the system is safe and efficient. The control logic of the key process parameters includes but is not limited to: a pressure transmitter is arranged at the outlet pipe of the pyrolysis furnace, and the signal thereof is connected with the frequency converter of the high-temperature waste gas fan 7 to maintain the outlet of the pyrolysis furnace in a set micro-negative pressure state (for example, -20 to -50 Pa), so as to avoid excessive negative pressure causing excessive loss of materials in the pyrolysis furnace, and at the same time, the dynamic balance between the exhaust capacity of the production line and the exhaust capacity of the high-temperature waste gas is realized by automatically adjusting the frequency of the fan. A pressure transmitter is arranged in the direct combustion furnace 12, and the signal thereof is connected with the frequency converter of the terminal induced fan 25 to maintain the micro-negative pressure (for example, -50 to -100 Pa) in the direct combustion furnace, so as to realize stable negative pressure combustion and realize energy saving and consumption reduction by adjusting the frequency of the fan. A temperature transmitter is arranged in the direct combustion furnace 12, and the signal thereof is connected with the steam supplement control valve, so that when the hearth temperature exceeds the set upper limit, steam is automatically supplemented for cooling. The alkali washing tower is provided with instruments such as a liquid level meter, a pH meter and an electric conductivity meter with remote transmission function, so as to automatically add alkali solution according to the pH meter data, automatically supplement water according to the liquid level meter, and automatically control the waste water discharge pump to discharge waste water according to the electric conductivity. The waste water treatment unit can automatically control the addition amount of quicklime according to the flow meter. The on-line monitoring system (CEMS) of the chimney discharge port can measure the O2 content, which is used to feedback adjust the air distribution of the burner and the amount of cooling steam. The operator only needs to set and monitor through the human-machine interface (HMI), and presses the start key to realize the automatic operation of the system. The design of the whole control system ensures stable and reliable operation, quick response, and strict operation according to the process requirements, so as to maximize the reduction of energy consumption and save production cost while ensuring efficient treatment of waste gas and waste liquid.

[0053] As can be seen from the detailed description of the above specific embodiment, the waste gas and waste liquid treatment system and method provided by the utility model have many advantages compared with the prior art. First, in terms of pollutant treatment efficiency, the process path combining high-temperature incineration of the direct combustion furnace, rapid quenching of the flue gas and subsequent multi-stage wet washing and activated carbon deep adsorption can realize efficient and collaborative removal of VOCs, HF and potential dioxin substances, so as to ensure that the final emission strictly meets the requirements and ensures environmental safety.

[0054] Secondly, in terms of energy utilization and economic benefits, the utility model innovatively uses waste gas and waste liquid as fuel of the direct-fired furnace for resource utilization, which significantly reduces the dependence on external supplementary fuel (such as natural gas). More importantly, through the two-stage waste heat recovery system of the steam boiler and the hot water heat exchanger, the high-temperature flue gas heat energy generated by incineration is utilized in stages and efficiently, and the generated steam and hot water can be directly applied to the production process or living facilities, which greatly reduces the overall energy consumption cost of the enterprise, thereby bringing considerable direct economic benefits and improving the overall energy efficiency of the process.

[0055] Furthermore, in terms of reliability and durability of the equipment operation, the utility model uses special chrome corundum refractory castable for the lining material of key high-temperature equipment (such as direct-fired furnace and semi-dry quenching tower) in view of the strong corrosive components (such as HF) in waste gas, which significantly enhances the corrosion resistance of the equipment. At the same time, through special design of the high-temperature dust collector (such as nitrogen dehumidification and heating) and heat tracing and insulation measures for high-temperature pipelines, condensation and coking of high-boiling-point organic matter in low-temperature areas are effectively prevented, and the problem of equipment blockage caused thereby is avoided. In addition, the one-use-one-backup configuration of key equipment (such as high-temperature fan) and comprehensive safety interlocking design jointly ensure the long-period, safe and stable operation of the entire treatment system.

[0056] In addition, in terms of environmental protection and sustainable development, the double-alkali method for treating and fully recycling the washing wastewater adopted by the utility model successfully achieves the zero-emission goal of process wastewater, not only saving valuable fresh water resources, but also fundamentally eliminating the environmental risks that may be caused by wastewater discharge. Compared with the traditional dry or semi-dry deacidification process, the utility model greatly reduces the amount of solid waste such as lime residue and waste cloth bag, only produces a small amount of inorganic salt cake after pressure filtration dewatering, greatly reduces the disposal pressure and related costs of secondary solid waste, and is more in line with the concept of circular economy and clean production.

[0057] Finally, in terms of safety and intelligent level of system operation, the utility model designs the closed safe transportation of high-temperature and high-concentration anaerobic pyrolysis gas, the low-nitrogen staged combustion of mixed fuel, and the use of battery crushing plant waste gas as part of the combustion-supporting air, and is supplemented by multiple safety protection measures such as flame arrestor, double shut-off valve and emergency emptying, which effectively avoids the safety risks such as flash explosion that may be caused by direct mixing of high-temperature and high-concentration waste gas with a large amount of air. The entire system relies on PLC to realize full automation control and interlocking protection, which not only greatly reduces the labor intensity and potential human error risk of manual operation, saves valuable human resources, but also simplifies the daily operation, maintenance and management work, and improves the overall operation efficiency and intelligent management level of the system.

[0058] In summary, the specific embodiment of the utility model through a series of innovative design and integrated optimization, successfully built a set of efficient, energy saving, environmental protection, safe and economic and feasible waste lithium battery recycling waste gas and waste liquid comprehensive treatment solution.

[0059] Example 1:

[0060] Taking a 2.5t / h capacity of waste lithium battery recycling production line as an example, the waste gas and waste liquid treatment system related parameters in the processing process are calculated.

[0061] The pyrolysis furnace heats the gas generated by the volatilization and cracking of electrolyte, separator and binder (PVDF), and the total amount of the material pyrolyzed into gas is about 15% of the total weight of the battery, and the total amount of the material pyrolyzed is 375kg / h. Among them, the theoretical amount of fluorinated physical is about 8.7kg / h.

[0062] Direct combustion furnace selection parameter example:

[0063] Waste gas and waste liquid organic matter treatment amount: 375kg / h

[0064] Natural gas (long-lasting fire / auxiliary): 5Nm 3 / h (dynamically adjusted according to the actual waste gas heat value)

[0065] Pyrolysis furnace high-temperature high-concentration waste gas design air volume: 500Nm 3 / h (determined according to the actual gas production of pyrolysis process)

[0066] Low-concentration normal-temperature oxygen-containing organic waste gas after battery crushing: 7500Nm 3 / h (as a combustion-supporting air, configured according to the total oxygen demand of the direct combustion furnace)

[0067] Direct combustion furnace flue gas residence time: 2.5s

[0068] Direct combustion furnace lining: refractory fiber cotton + light castable + chrome corundum castable (Cr2O3 content 12% ~ 15%, preferably 13%)

[0069] Direct combustion furnace steel plate thickness: 10mm

[0070] Direct combustion furnace design normal working temperature: ≥850, preferably 950℃

[0071] Direct combustion furnace design maximum working temperature: 1400℃ (allow short-time overtemperature)

[0072] Direct combustion furnace design load regulation range: 30% ~ 150%

[0073] Steam boiler selection parameter example:

[0074] Imported flue gas amount: about 8000Nm 3 / h (pyrolysis off-gas + broken off-gas + natural gas combustion products)

[0075] Inlet flue gas temperature: about 950-1100°C, preferably 1100°C

[0076] Outlet flue gas temperature: 500°C

[0077] Steam pressure (gauge pressure): 1.0 MPaG

[0078] Steam temperature (saturated steam): 184°C

[0079] Feed water temperature: 45°C

[0080] Feed water pressure: 1.5 MPaG

[0081] Nominal evaporation: about 3 t / h (calculated accurately according to flue gas volume and temperature drop)

[0082] Example of high-temperature off-gas fan selection parameters:

[0083] Form: centrifugal fan

[0084] Air volume: 1000 Nm 3 / h (considering a certain margin)

[0085] Operating temperature: 300°C (designed to withstand 450°C)

[0086] Static pressure: 7000 Pa

[0087] Power: 7.5 kW

[0088] Transmission method: coupling

[0089] Material: impeller SUS310S, shell SUS304, outer package insulation shell, nitrogen seal.

[0090] Example of end induced draft fan selection parameters:

[0091] Form: centrifugal fan

[0092] Air volume: 15000 Nm 3 / h (considering the total air volume of the system and a certain margin)

[0093] Operating temperature: 30°C

[0094] Static pressure: 7000 Pa

[0095] Power: 55 kW

[0096] Transmission method: belt

[0097] Material: impeller and flow parts made of glass fiber reinforced plastic or other corrosion-resistant materials.

[0098] Running effect estimation:

[0099] After accounting, the waste gas and waste liquid coupling steam boiler and the waste heat utilization process of the hot water heat exchanger in the direct combustion furnace incineration waste lithium battery recycling process can produce 3t steam per hour, can create economic benefits 475 million yuan per year, the one-time investment cost of the equipment is about 400 million yuan, the investment recovery period is less than 1 year, and it has good economic benefits.

[0100] The above examples are only preferred examples of the technical scheme of the utility model, and are not a limitation on the protection scope of the utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

[0101] Although some specific embodiments of the utility model have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, and are not intended to limit the scope of the utility model. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the utility model. The scope of the utility model is defined by the appended claims.

Claims

1. A waste gas and liquid treatment system in a waste lithium battery recycling process, characterized in that, The application relates to a lithium battery recycling system. The system comprises: at least one waste gas introduction and pretreatment unit for introducing and pretreating waste gas containing target pollutants generated in a lithium battery recycling process; an organic waste liquid introduction unit for introducing organic waste liquid generated in the lithium battery recycling process; a direct combustion incineration unit provided with a combustion device capable of receiving and incinerating the pretreated waste gas and the organic waste liquid, for oxidizing and decomposing the target pollutants and the organic waste liquid at high temperature; a flue gas purification and waste heat recovery unit connected to a flue gas outlet of the direct combustion incineration unit, for cooling, waste heat recovery, acid gas absorption and final purification of high-temperature flue gas generated in the incineration; 2. The system of claim 1, wherein, a washing wastewater treatment and recycling unit for treating washing wastewater generated in the flue gas purification process, and recycling the treated water to the flue gas purification and waste heat recovery unit. The at least one waste gas introduction and pretreatment unit comprises: a first waste gas introduction and pretreatment branch for treating normal-temperature oxygen-containing organic waste gas generated in a battery crushing workshop, which comprises a normal-temperature dust removal device and a first waste gas conveying device; and / or 3. The system of claim 2, wherein, a second waste gas introduction and pretreatment branch for treating high-temperature anaerobic organic waste gas generated in a pyrolysis furnace, which comprises a high-temperature dust removal device and a second waste gas conveying device, and the high-temperature dust removal device and its conveying pipeline are provided with high-temperature heat tracing and heat preservation measures.

4. The system of claim 1, wherein, The organic waste liquid introduction unit comprises a liquid collecting tank and a waste liquid conveying pump in communication with a conveying pipeline of the second waste gas introduction and pretreatment branch, for collecting and conveying organic waste liquid condensed in the conveying pipeline to the direct combustion incineration unit.

5. The system of claim 4, wherein, The combustion device of the direct combustion incineration unit is a mixed fuel low-nitrogen burner, and the hearth lining of the direct combustion incineration unit is made of corrosion-resistant refractory material.

6. The system of claim 1, wherein, The corrosion-resistant refractory material is chrome corundum castable. The flue gas purification and waste heat recovery unit comprises, in sequence: a first waste heat recovery device for recovering steam generated by high-temperature flue gas heat; a flue gas quenching device for rapidly cooling flue gas cooled by the first waste heat recovery device to a predetermined temperature to inhibit the generation of dioxins; an acid gas absorption device for absorbing acid gas in the flue gas, which is provided with a second waste heat recovery device on a circulating washing liquid pipeline for recovering flue gas waste heat to generate hot water; 7. The system of claim 6, wherein, a tail gas final purification device for adsorbing trace amounts of organic pollutants remaining in the flue gas. The first waste heat recovery device is a steam boiler, the second waste heat recovery device is a hot water heat exchanger, the acid gas absorption device comprises at least one alkali washing tower and a demister, and the tail gas final purification device is an activated carbon adsorption bed.

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