Dehydration, rectification and incineration coupled energy-saving treatment process for waste organic solution

Abstract

The invention belongs to the technical field of energy conservation and environmental protection, and particularly relates to a waste organic solution dehydration, rectification and incineration coupling energy-saving treatment process which comprises the steps that a waste organic solution is pretreated, and impurities are removed; rectifying and purifying the pretreated waste organic solvent, and separating the organic solvent from residual materials; the impurities and / or the residual materials are fed into an incineration device to be incinerated, and at least part of heat needed by rectification and purification is provided by incineration. According to the invention, two separate treatment processes of traditional resource recycling and incineration are fused into one set of process, so that thermal coupling of rectification and incineration is realized, more energy is saved, recycling of waste organic solvents can be realized, other impurities, residues and the like can be incinerated relatively thoroughly, and environmental pollution is reduced. Impurities, residues and the like do not need to be transferred and transported, so that the safety and environmental risks are reduced. The incinerated high-temperature tail gas does work, so that the cost of a high-cost compressor, a high-cost reboiler and the like is saved, and the cost is further reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of energy conservation and environmental protection, and specifically relates to a waste organic solution dehydration rectification incineration coupling energy-saving treatment process. Background Art

[0002] As hazardous wastes generated by the pharmaceutical, chemical, leather and other manufacturing industries, waste solvents contain a certain amount of impurities - water. At present, there are two ways to dispose of hazardous wastes: one is resource utilization, that is, the valuable components in the waste are extracted through a variety of separation technologies and then recycled as products; the other is incineration, in the presence of sufficient oxygen, to fully burn, completely oxidize and completely destroy the hazardous wastes.

[0003] If only resource utilization is adopted, the disposal of hazardous waste will not be thorough, and a certain amount of secondary hazardous waste will be generated. This waste needs to be further disposed of, which increases the disposal cost. In addition, there are still certain safety and environmental risks during the transfer process. If only incineration is used to dispose of waste liquid, it will lead to the waste of useful resources in the waste liquid. At the same time, large-scale incineration increases the processing burden of incineration equipment, and a large amount of carbon dioxide will be produced after incineration, which is not in line with the current dual-carbon policy. In addition, the water in the waste solvent has no calorific value, and a large amount of energy is consumed during incineration, which makes the process complicated and increases the operating cost.

[0004] like Figure 1 As shown in the figure, the use of ordinary distillation dehydration has the disadvantage of huge energy consumption. First, the condensation latent heat of the tower top steam is often directly discharged into the environment without being effectively recovered and utilized, resulting in low thermal energy utilization. Secondly, the manufacture and installation of the distillation system requires a large number of other equipment, such as pumps, storage tanks, condensers and reboilers, etc., and the equipment cost is relatively high.

[0005] like Figure 2 As shown in the figure, if only the heat pump distillation process is used, the residue treatment is not thorough and heat energy is wasted. Furthermore, the core equipment of the general heat pump distillation is the compressor, which has a high purchase price. In addition, in order to maintain normal operation, the compressor needs to use a large amount of electricity, and the operating cost is high. Summary of the invention

[0006] In order to solve the defects of the prior art, such as high equipment cost and incomplete waste treatment, the present invention provides a waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process.

[0007] The technical solution adopted by the present invention is as follows: a waste organic solution dehydration distillation incineration coupled energy-saving treatment process, including pretreatment of the waste organic solution to remove impurities; distillation and purification of the pretreated waste organic solvent to separate the organic solvent and residual materials; impurities and / or residual materials are sent to an incineration device for incineration, and the heat required for the distillation and purification is at least partially provided by the incineration.

[0008] Furthermore, the non-target organic solvent produced by distillation is sent to the incineration device for incineration.

[0009] Specifically, the residual material includes residual liquid and / or residue remaining after distillation.

[0010] Furthermore, part of the target organic solvent produced by distillation is sent to the incineration device for incineration.

[0011] Furthermore, other organic waste liquids are added to the incineration device for combustion.

[0012] Preferably, it also includes a heat exchanger for further heating the distillation product and a condenser for condensing the distillation product after heat exchange in the heat exchanger. The heat generated by the incineration device is at least partially passed into the heat exchanger, and the heat after heat exchange between the condenser and the distillation product is supplied to the distillation purification process.

[0013] Beneficial effects:

[0014] The present invention integrates the two traditional separate disposal processes of resource recycling and incineration into one set of processes, realizes thermal coupling of distillation and incineration, is more energy-efficient, and can not only realize the recycling of waste organic solvents, but also can incinerate other impurities, residues, etc. to treat them relatively thoroughly, without the need to transfer and transport impurities, residues, etc., thereby reducing safety and environmental risks.

[0015] The present invention uses the incinerated high-temperature tail gas to do work, thereby saving the cost of high-cost compressors, reboilers, etc., and further reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram of the traditional distillation process;

[0017] Figure 2 This is a common heat pump distillation process diagram;

[0018] Figure 3 This is a distillation process diagram of the present invention.

[0019] Among them: 1. distillation tower, 2. condenser, 3. compressor, 4. heat exchanger. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific implementation methods. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative changes belong to the protection scope of the present invention.

[0021] like Figure 1 In the conventional distillation process in the prior art, the latent heat of condensation of the steam at the top of the tower is often directly discharged into the environment without being effectively recovered and utilized, resulting in a low thermal energy utilization rate.

[0022] like Figure 2 As shown, it is a common heat pump distillation process flow, which utilizes the heat pump principle to absorb and utilize the heat in the environment, but does not process the distillation residue, etc. In addition, the process requires the use of an expensive compressor 3, and a large amount of electricity is required to supply the heat pump compressor 3 system, resulting in a high operating cost.

[0023] In order to solve the above technical problems, the present invention provides a waste organic solution dehydration distillation incineration coupled energy-saving treatment process, including pre-treating the waste organic solution to remove impurities; distilling and purifying the pretreated waste organic solvent to separate the organic solvent and residual materials; sending the impurities and / or residual materials into an incineration device for incineration, and the heat required for the distillation and purification is at least partially provided by the incineration.

[0024] The present invention pre-treats the waste organic solution, removes impurities such as residues and heavy components, and incinerates the impurities. The heat generated after incineration is used as a heat source for distillation and purification of the waste organic solvent. Not only can the target organic matter and organic solvent be distilled and recovered, but also the impurities such as residues and residual materials of the distillation are incinerated. The heat generated is supplied to the distillation process, thereby realizing the coupling of distillation and incineration, the process is more energy-saving, and the waste treatment is more thorough.

[0025] In some embodiments, the non-target organic solvent produced by distillation is sent to the incineration device for incineration. Some non-solid impurities are difficult to remove through the pretreatment process and can only be removed during the distillation process, but the non-target organic products can still be incinerated to provide distillation heat.

[0026] Specifically, the residual material includes residual liquid and / or residue remaining after distillation.

[0027] In some embodiments, part of the target organic solvent produced by distillation is sent to the incineration device for incineration. When the incineration device needs to provide a large amount of fuel, the output of the target organic matter can be reduced, and part of the target organic matter organic solvent is also sent to the incineration device for incineration to provide heat.

[0028] In some embodiments, other organic waste liquids are added to the incineration device for combustion. When the incineration device needs to provide a large amount of fuel, but impurities, residual liquids, residues, non-target products, etc. are insufficient to supply, and the target product has a large market sales volume, other organic waste liquids can be added as supplementary fuel to improve process flexibility and controllability.

[0029] In some embodiments, it also includes a heat exchanger 4 for further heating the distillation product, and a condenser 2 for condensing the distillation product after heat exchange in the heat exchanger 4. The heat generated by the incineration device is at least partially passed into the heat exchanger 4, and the heat after the condenser 2 and the distillation product exchange heat is supplied to the distillation purification process. The heat generated by the incineration device can further increase the temperature and pressure of the distillation product through the heat exchanger 4 to increase its thermal enthalpy. After the distillation product is condensed into a liquid phase in the condenser 2, it will release heat. The heat transfer medium in the condenser 2 absorbs the heat and returns to the distillation tower 1. The present invention replaces the compressor 3, the core equipment of ordinary heat pump distillation, with a heat exchanger 4, which can further reduce equipment costs.

[0030] The process of the present invention is further described below in combination with practical applications.

[0031] Example 1

[0032] Ethanol waste liquid from pharmaceutical industry

[0033] The waste liquid comes from the pharmaceutical industry. Ethanol is a commonly used organic cleaning agent for cleaning various devices. According to business analysis, the ethanol waste liquid of a pharmaceutical factory in Suzhou has the following components: 3% water, 10% methanol, 75% ethanol, and 12% other heavy component impurities such as propanol, ethylene glycol, and butanol.

[0034] In this process, dichloromethane is added as an azeotropic agent in the first step, and forms an azeotropic mixture with the water in the waste liquid during distillation to take away the water, and the temperature is 38-39°C. The azeotropic mixture after condensation will form layers, and the upper organic phase is dichloromethane, which can be recycled, and the lower water is treated at the sewage station.

[0035] In the second step, the dehydrated ethanol solvent is sent to the intermittent distillation tower 1 to recover useful components. The temperature at the top of the tower is first controlled at about 65°C to produce the product methanol. Then the top temperature rises to about 78°C to produce the product ethanol. During the distillation process, the top temperature of the tower continues to rise, and the interval from 66°C to 77°C is the transition component, which is produced and sent to the incinerator as incineration fuel.

[0036] In the third step, when the top temperature of the distillation tower 1 exceeds 79°C, the distillation is terminated and all the residual materials are sent to the incinerator as fuel.

[0037] In this process, the distillation rate can be adjusted according to the fuel demand of the incinerator, that is, the amount of excessive components and residual materials can be controlled by operating the reflux ratio. When a large amount of fuel is needed, the output of ethanol and methanol products can be reduced, and more waste liquids such as excessive components and residual materials enter the incinerator as a heat source of the distillation tower 1 as fuel. As needed, part of the ethanol and methanol distilled can also be directly sent to the incinerator. When the market sales of ethanol and methanol products are large, other organic waste liquids can be burned as supplementary fuel to generate heat for distillation. Of course, additional heat is required when the equipment is started. Therefore, this process has good controllability.

[0038] Example 2

[0039] N-methylpyrrolidone waste liquid in lithium battery industry

[0040] The waste liquid comes from the new energy industry. According to business analysis, the components of N-methylpyrrolidone waste liquid from a lithium battery factory in Changzhou are as follows: 1% water, 92% N-methylpyrrolidone, 3% solid powder, and 4% other heavy component impurities.

[0041] In this process, the waste liquid is first pretreated by simple distillation in the first distillation tower 1. The top temperature of the first distillation tower 1 is controlled at about 110°C to obtain a crude N-methylpyrrolidone product containing about 10% water. The removed heavy component impurities and solid powder are sent to the incinerator as residue for incineration.

[0042] The crude N-methylpyrrolidone from the first distillation tower 1 is sent to the second distillation tower 1 for further refinement, and a continuous distillation production method is adopted. The bottom temperature of the second distillation tower 1 is controlled at 203°C to obtain an N-methylpyrrolidone product with a water content of less than 500 PPM.

[0043] The top product of the second distillation tower 1 enters the heat exchanger 4 to be heated and pressurized by the heat generated by incineration, and the temperature rises to 220°C, and then enters the condenser 2 to release heat. The top product after heat release can be sent to the incineration tower for incineration to release heat.

[0044] In this process, since the recovery rate of N-methylpyrrolidone is ≥80%, there are fewer waste liquid components that can be used as fuel. According to actual needs, other waste liquids can be incinerated as fuel as a source of distillation steam. Since N-methylpyrrolidone has a wide range of uses, a high price, and a high processing added value, its recovery rate is strictly controlled, and the process of using other waste liquids as fuel still has high economic benefits.

[0045] Example 3

[0046] Ethylbenzene and xylene solutions in the chemical industry

[0047] The waste liquid comes from the traditional chemical industry, and the waste liquid components are as follows: 5% water, 45% ethylbenzene, 48% p-xylene, and 2% other impurities (mass fraction). The separation of ethylbenzene and xylene waste liquid is a common problem in the chemical industry. Due to the close boiling points, a large number of theoretical plates are required, and the energy consumption is huge. The advantages of using this process are obvious.

[0048] In this process, the waste liquid is directly sent to the distillation tower 1 for distillation after filtering and pretreatment, and the pretreated impurities are sent to the incineration device for incineration. The tower top temperature is controlled at 98°C, and water and ethylbenzene vapor are produced. Figure 3 , the water and ethylbenzene vapor produced from the top of the tower enter the heat exchanger 4. The heat source of the heat exchanger 4 is the high-temperature tail gas after incineration, and the temperature is about 220°C. The water and ethylbenzene vapor are heated in the heat exchanger 4, and the heating pressure in the heat exchanger 4 is controlled to be 0.35-0.4MPa. The temperature of the heated water and ethylbenzene vapor can reach 145°C, and enter the condenser 2 to release its heat (the heat returns to the distillation tower 1). After the temperature is lowered, the water and ethylbenzene are condensed into a liquid phase. After condensation, the layers will be separated, and the water phase will be obtained in the lower layer, which will be disposed of in the sewage station. The upper layer is the organic phase, which is ethylbenzene, and can be reused in the chemical plant. The recovery rate of ethylbenzene after resource utilization can reach more than 95%, and the concentration is 98%.

[0049] The bottom product is paraxylene, and other impurities are incinerated. Since paraxylene has a wide range of uses, the higher the concentration, the higher the added value. When treating the waste liquid, this process selects a higher concentration of xylene and a lower recovery rate. On the one hand, the recovery rate is to meet the requirements of high purity of the product and reduce the output; on the other hand, the yield is reduced, and more paraxylene is incinerated as fuel to generate heat, which meets the thermal coupling of heat. Under this condition, the recovery rate of paraxylene is 45% and the concentration is 99.5%.

Claims

1. A waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process, characterized in that: The method comprises pre-treating the waste organic solution to remove impurities; distilling and purifying the pre-treated waste organic solvent to separate the organic solvent and residual materials; sending the impurities and / or residual materials into an incineration device for incineration, wherein the heat required for the distillation and purification is at least partially provided by the incineration.

2. The waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process according to claim 1 is characterized in that: The non-target organic solvent produced by distillation is sent to the incineration device for incineration.

3. The waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process according to claim 1 or 2, characterized in that: The residual material includes residual liquid and / or residue remaining after distillation.

4. The waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process according to claim 1 is characterized in that: Part of the target organic solvent produced by distillation is sent to the incineration device for incineration.

5. The waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process according to claim 1 is characterized in that: Other organic waste liquids are added to the incineration device for combustion.

6. The waste organic solution dehydration, distillation and incineration coupled energy-saving treatment process according to claim 1 is characterized in that: It also includes a heat exchanger for further heating the distillation product and a condenser for condensing the distillation product after heat exchange in the heat exchanger. The heat generated by the incineration device is at least partially passed into the heat exchanger, and the heat after heat exchange between the condenser and the distillation product is supplied to the distillation purification process.

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