System and method for multi-stage reboiling and concentration of organic waste liquid

Abstract

The invention discloses a system and method for multi-stage reboiler concentration of organic waste liquid. The system includes a distillation unit, a steam condensate storage unit, a sewage treatment unit and n-stage reboiler units connected in series. The distillation unit is connected to the sewage treatment unit. The distillation unit includes a distillation tower. The distillation tower includes a tower kettle and a tower body. The tower kettle has n-stage mutually isolated liquid storage tanks. The first-stage liquid storage tank is connected to the tower body and the second-stage liquid storage tank to the n-th-stage liquid storage tank are isolated from the tower body. n is a positive integer greater than or equal to 3. Each stage of the reboiler unit is connected to the tower body and the steam condensate storage unit. The first-stage reboiler unit is connected to the first-stage liquid storage tank and the second-stage liquid storage tank. The second-stage reboiler unit is connected to the second-stage liquid storage tank and the third-stage liquid storage tank. The n-th-stage reboiler unit is connected to the n-stage liquid storage tank. The system for multi-stage reboiler concentration of organic waste liquid of the invention can ensure the concentration of concentrated products, reduce the number of equipment, and effectively reduce costs.

Description

Technical Field

[0001] The invention belongs to the technical field of organic waste liquid treatment, and specifically relates to a system for multi-stage reboiling and concentration of organic waste liquid and a method for multi-stage reboiling and concentration of organic waste liquid based on the system. Background Art

[0002] A large amount of low-concentration wastewater solution is generated in the production process of printing and dyeing, leather, membrane, polyurethane (PU slurry), electronics, artificial fiber, pharmaceutical and food additive industries. Since the wastewater concentration is low and contains substances with recycling value, it is difficult and costly to treat it directly as sewage. If substances with recycling value are separated, it can not only help enterprises reduce production costs, but also achieve the goals of environmental protection, reduction and harmlessness. The current separation process mainly relies on distillation equipment, membrane equipment, extractants, etc. In comparison, distillation separation is more widely used.

[0003] At present, the mainstream waste liquid concentration processes in the industry include single-effect concentration, multi-effect concentration, membrane concentration, MVR heat pump concentration, etc. Among them, multi-effect concentration is a series evaporation operation that uses the secondary steam of the previous effect as the heating steam of the next effect; membrane concentration uses the difference in molecular weight between the effective components and the liquid to achieve directional separation and achieve the effect of concentration; MVR heat pump concentration is low-grade steam compressed by a compressor, the temperature and pressure are increased, the thermal enthalpy is increased, and then enters the heat exchanger for condensation to fully utilize the latent heat of steam. Among the above-mentioned concentration processes, the equipment for multi-effect concentration occupies a large area; the membrane concentration process has relatively high requirements on the corrosiveness and impurities of wastewater; the equipment for multi-effect concentration is relatively large and occupies a relatively large area; the investment cost of heat pump concentration is high. Summary of the invention

[0004] In view of this, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a system and method for multi-stage reboiling and concentration of organic waste liquid, which can not only ensure the purity of the concentrated product, but also effectively reduce the number of equipment and the equipment footprint, thereby effectively reducing the investment cost.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a system for multi-stage reboiling and concentrating organic waste liquid, comprising a distillation unit, a steam condensate storage unit, a sewage treatment unit and n-stage reboiler units connected in series, wherein the distillation unit is connected to the sewage treatment unit, the distillation unit comprises a distillation tower, the distillation tower comprises a tower kettle and a tower body, the tower kettle of the distillation tower has n-stage mutually isolated liquid storage tanks, the first-stage liquid storage tank is connected to the tower body and the second-stage liquid storage tank to the n-th-stage liquid storage tank are isolated from the tower body, and n is a positive integer greater than or equal to 3; each stage of the reboiler unit is connected to the tower body and the steam condensate storage unit, the first-stage liquid storage tank is provided with an organic waste liquid inlet pipe, the first-stage reboiler unit is connected to the first-stage liquid storage tank and the second-stage liquid storage tank, the second-stage reboiler unit is connected to the second-stage liquid storage tank and the third-stage liquid storage tank, the n-stage reboiler unit is connected to the n-stage liquid storage tank, and the organic waste liquid is discharged from the bottom of the n-stage liquid storage tank after multi-stage reboiler concentration.

[0007] The present invention forms high-concentration waste liquid by concentrating the organic waste liquid step by step from the first-stage reboiler unit to the n-stage reboiler unit. In the case of only one distillation tower, the investment cost is greatly reduced, too many towers are not required, and the equipment footprint can be effectively reduced.

[0008] According to some preferred implementation aspects of the present invention, the volume of the liquid storage tank gradually decreases from the first stage to the nth stage. The reason for this arrangement is that after the organic waste liquid is concentrated by multi-stage reboiling, the water content in the waste liquid decreases, and the amount that needs to be evaporated becomes less and less, so the volume of the liquid storage tank can be reduced step by step.

[0009] According to some preferred implementation aspects of the present invention, the top surface of each level of the liquid storage tank is located on the same plane, the top surface of the first level liquid storage tank has a through opening, and the top surfaces of the second level liquid storage tank to the nth level liquid storage tank are commonly provided with a cover plate. The cover plate is provided to prevent the upper liquid from entering the second level liquid storage tank to the nth level liquid storage tank, because the organic waste liquid in the second level liquid storage tank to the nth level liquid storage tank has been further reboiled and concentrated, and its concentration has been increased to varying degrees. If the upper liquid flows back to the second level liquid storage tank to the nth level liquid storage tank, the concentration of the organic waste liquid stored therein will be reduced, and the meaning of reboiled and concentrated step by step is lost.

[0010] According to some preferred embodiments of the present invention, each level of the liquid storage tank is provided with a liquid level meter, which is used to display the liquid level height in the corresponding liquid storage tank in real time and is used in conjunction with a liquid level control valve to control the feed of each level of the liquid storage tank according to the liquid level.

[0011] According to some preferred implementation aspects of the present invention, each stage of the reboiler unit includes a reboiler, a discharge pump, a first pipeline, a second pipeline, and a third pipeline, wherein the first pipeline connects the bottom of each stage of the liquid storage tank with the discharge pump, the second pipeline connects the discharge pump with the top of the reboiler, and the third pipeline connects the bottom of the reboiler with the middle of each stage of the liquid storage tank. In some embodiments of the present invention, each reboiler is also connected to a steam supply unit to provide heat for the reboiler.

[0012] According to some preferred embodiments of the present invention, the first-stage reboiler unit to the n-1th stage reboiler unit also include a first branch pipe, one end of which is connected to the second pipeline, and the first branch pipe connects the discharge pump of the n-2th stage reboiler unit and the liquid storage tank of the n-1th stage reboiler unit.

[0013] According to some preferred embodiments of the present invention, a first liquid level control valve is provided on the organic waste liquid inlet pipe, a second liquid level control valve is provided on each of the first branch pipes, the liquid level gauge of the first-stage liquid storage tank is connected to the first liquid level control valve, and the liquid level gauge of the n-1th stage liquid storage tank is connected to the second liquid level control valve in the n-2th stage reboiler unit.

[0014] According to some preferred embodiments of the present invention, when the liquid level height of the liquid level gauge is less than 1m, the first liquid level control valve and / or the second liquid level control valve is opened; when the liquid level height of the liquid level gauge is greater than 1.5m, the first liquid level control valve and / or the second liquid level control valve is closed.

[0015] According to some preferred implementation aspects of the present invention, the tower body includes a cavity section, a packing section and a tower top, the cavity section is located between the tower bottom and the packing section, the cavity section is connected to the first-stage liquid storage tank, and a plurality of packing layers are evenly spaced along the height direction of the packing section, and a liquid distributor is arranged above each of the packing layers. The arrangement of the liquid distributor can ensure that the liquid refluxed from the top of the distillation tower flows down evenly. In addition, the packing layer is provided with at least three layers to ensure sufficient contact between the gas-liquid two phases in the distillation tower.

[0016] According to some preferred embodiments of the present invention, each stage of the reboiler unit further includes a fourth pipe, each side of the reboiler has a gas phase outlet, and the fourth pipe is used to connect the gas phase outlet of the reboiler with the cavity section.

[0017] According to some preferred embodiments of the present invention, the n-stage reboiler unit further includes a second branch pipe, one end of which is connected to the second pipe of the n-stage reboiler unit, and the organic waste liquid is discharged to the outside from the bottom of the n-stage liquid storage tank through the first pipe, the second pipe and the second branch pipe of the n-stage reboiler unit after multi-stage reboiler concentration.

[0018] According to some preferred embodiments of the present invention, each of the second pipelines is provided with a first valve, the second branch pipe is provided with a second valve, the first valves in the first-stage reboiler unit to the n-1-stage reboiler unit are located between the connection between the first branch pipe and the second pipeline and the top of the reboiler, and the first valve in the n-stage reboiler unit is located between the connection between the second branch pipe and the second pipeline and the top of the reboiler.

[0019] According to some preferred embodiments of the present invention, the concentration of the organic waste liquid entering the first-stage liquid storage tank through the organic waste liquid inlet pipe is 10%~25%, and the concentration of the organic waste liquid after reboiled and concentrated by the n-stage reboiler unit is 70%~80%.

[0020] According to some preferred embodiments of the present invention, the distillation unit further includes a condenser, a condensate tank and a first delivery pump. The top of the distillation tower is connected to the condenser, the condensate tank and the first delivery pump in sequence to form a closed loop. The first delivery pump is also connected to the sewage treatment unit.

[0021] According to some preferred embodiments of the present invention, the steam condensate storage unit includes a connected steam condensate tank and a second delivery pump, each of the reboilers is connected to the steam condensate tank, and the steam condensate tank is used to store the steam condensate generated in each of the reboilers.

[0022] The present invention also provides a method for multi-stage reboiling and concentrating organic waste liquid using the above-mentioned system for multi-stage reboiling and concentrating organic waste liquid, comprising the following steps:

[0023] The organic waste liquid is transported to the first-stage liquid storage tank and then sequentially reboiled and concentrated by the first-stage reboiler unit to the n-stage reboiler unit, and the liquid treated by the n-stage reboiler unit is discharged from the n-stage liquid storage tank;

[0024] The gas produced during the treatment process of each reboiler unit enters the distillation tower;

[0025] Part of the gas in the distillation tower is condensed during the rising process in the distillation tower due to gas-liquid exchange, and the liquid generated is returned to the first-stage liquid storage tank;

[0026] The remaining part of the gas in the distillation tower flows out from the top of the tower, and the condensate produced after condensation flows back to the top of the distillation tower and / or enters the sewage treatment unit for treatment. Specifically, the flow rate ratio of the condensate flowing back to the top of the tower and entering the sewage treatment unit is adjusted according to the content of organic solvent in the condensate at the top of the tower. When the content of organic solvent in the condensate at the top of the tower is greater than 1000ppm, the flow rate of the condensate flowing back to the top of the tower is increased; when the content of organic solvent in the condensate at the top of the tower is less than 1000ppm, the flow rate of the condensate flowing back to the top of the tower is reduced. Usually, the ratio of the flow rate of the condensate flowing back to the top of the tower to the flow rate of the condensate entering the sewage treatment unit is 0.6~1:1.

[0027] Compared with the prior art, the advantages of the present invention are as follows: the system and method for multi-stage reboiler concentration of organic waste liquid of the present invention, by setting n-stage reboiler units and setting n-stage liquid storage tanks in the bottom of a distillation tower, utilize the mutual cooperation between the n-stage liquid storage tanks and the n-stage reboiler units, pass low-concentration organic waste liquid into the first-stage liquid storage tank and be concentrated step by step from the first-stage reboiler unit to the n-stage reboiler unit, and form high-concentration waste liquid to be discharged from the n-stage liquid storage tank. In the case of only one distillation tower, not only the concentration of the concentrated product can be guaranteed, but also the number of equipment can be effectively reduced, the equipment footprint can be reduced, and the investment cost can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a schematic diagram of the structure of the multi-stage reboiling and concentration system for organic waste liquid in Example 1 of the present invention;

[0030] Figure 2 Schematic diagram of the top view of the distillation tower kettle in Example 1 of the present invention;

[0031] In the accompanying drawings, the reference numerals are:

[0032] Distillation tower-1, tower top-1a, packing layer-1b, liquid distributor-1c, cavity section-1d, first-stage liquid storage tank-1e, second-stage liquid storage tank-1f, third-stage liquid storage tank-1g, cover plate-1h, condenser-2, condensate tank-3, sewage tank-4, first-stage reboiler-5, second-stage reboiler-6, third-stage reboiler-7, first-stage discharge pump-8, second-stage discharge pump-9, third-stage discharge pump-10, first-stage liquid level gauge-11, second-stage liquid level gauge-12, third-stage liquid level gauge-13, organic waste liquid inlet pipe-14, first-stage first pipeline-15, first-stage second pipeline-16, first-stage third pipeline-17, first-stage fourth pipeline-18 , second-level first pipeline -19, second-level second pipeline -20, second-level third pipeline -21, second-level fourth pipeline -22, third-level first pipeline -23, third-level second pipeline -24, third-level third pipeline -25, third-level fourth pipeline -26, first-level first branch pipe -27, second-level first branch pipe -28, second branch pipe -29, first liquid level control valve -30, first-level second liquid level control valve -31, second-level second liquid level control valve -32, first-level first valve -33, second-level first valve -34, third-level first valve -35, second valve -36, first delivery pump -37, second delivery pump -38, steam condensate tank -39. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] Example 1 System for multi-stage reboiling and concentration of organic waste liquid

[0035] like Figure 1 and Figure 2 As shown, the multi-stage reboiling and concentration system for organic waste liquid in this embodiment includes a distillation unit, a steam condensate storage unit, a sewage treatment unit, and n-stage reboiler units connected in series, where n is a positive integer greater than or equal to 3; the distillation unit is connected to the sewage treatment unit, and each stage of the reboiler unit is connected to the distillation tower unit and the steam condensate storage unit. Among them, the distillation unit includes a distillation tower 1, and the distillation tower 1 includes a tower kettle and a tower body, and the tower kettle of the distillation tower 1 has n-stage mutually isolated liquid storage tanks. In this embodiment, n is three, that is, a system with three-stage reboiler units and three-stage liquid storage tanks is taken as an example for detailed introduction. Figure 1 The arrows in the diagram represent the direction of the material.

[0036] Specifically, the tower body of the distillation tower 1 includes a cavity section 1d, a packing section and a tower top 1a. The cavity section 1d is located between the tower bottom and the packing section. A plurality of packing layers 1b are evenly spaced along the height direction of the packing section. A liquid distributor 1c is provided above each packing layer 1b to ensure that the liquid refluxed from the tower top 1a of the distillation tower 1 can flow down evenly. The packing layer 1b in this embodiment is provided with three layers to ensure sufficient contact between the gas and liquid phases in the distillation tower 1. The packing layer 1b in this embodiment is a BX500 type wire mesh packing, and the height of each packing layer 1b is 3~4m.

[0037] The top surface of each level of liquid storage tank is located on the same plane. The top surface of the first level liquid storage tank 1e has a through hole to connect the first level liquid storage tank 1e with the cavity section 1d. The top surfaces of the second level liquid storage tank 1f and the third level liquid storage tank 1g are jointly provided with a cover plate 1h to ensure that the tower body of the distillation tower 1 can be connected with the first level liquid storage tank 1e. At the same time, the second level liquid storage tank 1f and the third level liquid storage tank 1g are isolated from the tower body to prevent the liquid above the tower bottom from entering the second level liquid storage tank 1f and the third level liquid storage tank 1g. In addition, the volume of the first level liquid storage tank 1e is greater than the volume of the second level liquid storage tank 1f, and the volume of the second level liquid storage tank 1f is greater than the volume of the third level liquid storage tank 1g. Moreover, the ratio of the volume of the first level liquid storage tank 1e to the second level liquid storage tank 1f and the third level liquid storage tank 1g is 20~30:10~20:5~10, preferably 3:2:1.

[0038] The first-stage liquid storage tank 1e is provided with a first-stage liquid level meter 11, the second-stage liquid storage tank 1f is provided with a second-stage liquid level meter 12, and the third-stage liquid storage tank 1g is provided with a third-stage liquid level meter 13, so as to respectively display the liquid level heights in the liquid storage tanks of each stage in real time; the first-stage liquid storage tank 1e is also connected to the organic waste liquid inlet pipe 14 to introduce organic waste liquid with a concentration of 10% to 25% into the first-stage liquid storage tank 1e, and a first liquid level control valve 30 is provided on the organic waste liquid inlet pipe 14, and The first-stage liquid level meter 11 is connected to the first liquid level control valve 30 to control the feed of the first-stage liquid storage tank 1e according to the liquid level in the first-stage liquid storage tank 1e. When the liquid level height of the first-stage liquid level meter 11 is less than 1m, the first liquid level control valve 30 opens to feed the first-stage liquid storage tank 1e through the organic waste liquid inlet pipe 14; when the liquid level height of the first-stage liquid level meter 11 is greater than 1.5m, the first liquid level control valve 30 closes to stop feeding into the first-stage liquid storage tank 1e.

[0039] In this embodiment, the first-stage reboiler unit includes a first-stage reboiler 5, a first-stage discharge pump 8, a first-stage first pipeline 15, a first-stage second pipeline 16, a first-stage third pipeline 17, a first-stage fourth pipeline 18 and a first-stage first branch pipe 27, and the side of the first-stage reboiler 5 has a gas phase outlet. Among them, the first-stage first pipeline 15 connects the bottom of the first-stage liquid storage tank 1e with the first-stage discharge pump 8, the first-stage second pipeline 16 connects the first-stage discharge pump 8 with the top of the first-stage reboiler 5, the first-stage third pipeline 17 connects the bottom of the first-stage reboiler 5 with the middle of the first-stage liquid storage tank 1e, and the first-stage fourth pipeline 18 connects the gas phase outlet of the first-stage reboiler 5 with the cavity section 1d. One end of the first-stage first branch pipe 27 is connected to the first-stage second pipeline 16, and the first-stage first branch pipe 27 connects the first-stage discharge pump 8 with the second-stage liquid storage tank 1f. The first-stage first branch pipe 27 is provided with a first-stage second liquid level control valve 31, and the second-stage liquid level gauge 12 is connected to the first-stage second liquid level control valve 31. When the liquid level height of the second-stage liquid level gauge 12 is less than 1m, the first-stage second liquid level control valve 31 is opened to feed the organic waste liquid (with a concentration of 30% to 40%) concentrated by the first-stage reboiler unit into the second-stage liquid storage tank 1f through the bottom of the first-stage liquid storage tank 1e, the first-stage first pipeline 15, the first-stage discharge pump 8, the first-stage second pipeline 16 and the first-stage first branch pipe 27; when the liquid level height of the second-stage liquid level gauge 12 is greater than 1.5m, the first-stage second liquid level control valve 31 is closed to stop feeding into the second-stage liquid storage tank 1f. The first-stage second pipeline 16 is provided with a first-stage first valve 33, and the first-stage first valve 33 is located between the connection between the first-stage first branch pipe 27 and the first-stage second pipeline 16 and the top of the first-stage reboiler 5.

[0040] The second-stage reboiler unit includes a second-stage reboiler 6, a second-stage discharge pump 9, a second-stage first pipeline 19, a second-stage second pipeline 20, a second-stage third pipeline 21, a second-stage fourth pipeline 22 and a second-stage first branch pipe 28. The side of the second-stage reboiler 6 also has a gas phase outlet. Among them, the second-stage first pipeline 19 connects the bottom of the second-stage liquid storage tank 1f with the second-stage discharge pump 9, the second-stage second pipeline 20 connects the second-stage discharge pump 9 with the top of the second-stage reboiler 6, the second-stage third pipeline 21 connects the bottom of the second-stage reboiler 6 with the middle of the second-stage liquid storage tank 1f, and the second-stage fourth pipeline 22 connects the gas phase outlet of the second-stage reboiler 6 with the cavity section 1d; one end of the second-stage first branch pipe 28 is connected to the second-stage second pipeline 20, and the second-stage first branch pipe 28 connects the second-stage discharge pump 9 with the third-stage liquid storage tank 1g. The second-stage first branch pipe 28 is provided with a second-stage second liquid level control valve 32, and the third-stage liquid level gauge 13 is connected to the second-stage second liquid level control valve 32. When the liquid level of the third-stage liquid level gauge 13 is less than 1m, the second-stage second liquid level control valve 32 is opened to feed the organic waste liquid (with a concentration of 45% to 50%) concentrated by the second-stage reboiler unit into the third-stage liquid storage tank 1g through the bottom of the second-stage liquid storage tank 1f, the second-stage first pipeline 19, the second-stage discharge pump 9, the second-stage second pipeline 20 and the second-stage first branch pipe 28; when the liquid level of the third-stage liquid level gauge 13 is greater than 1.5m, the second-stage second liquid level control valve 32 is closed to stop feeding into the third-stage liquid storage tank 1g. The second-stage second pipeline 20 is provided with a second-stage first valve 34, and the second-stage first valve 34 is located between the connection between the second-stage first branch pipe 28 and the second-stage second pipeline 20 and the top of the second-stage reboiler 6.

[0041] The third-stage reboiler unit includes a third-stage reboiler 7, a third-stage discharge pump 10, a third-stage first pipeline 23, a third-stage second pipeline 24, a third-stage third pipeline 25, a third-stage fourth pipeline 26 and a second branch pipe 29, a second valve 36 is provided on the second branch pipe 29, and the side of the third-stage reboiler 7 also has a gas phase outlet. Among them, the third-stage first pipeline 23 connects the bottom of the third-stage liquid storage tank 1g with the third-stage discharge pump 10, the third-stage second pipeline 24 connects the third-stage discharge pump 10 with the top of the third-stage reboiler 7, the third-stage third pipeline 25 connects the bottom of the third-stage reboiler 7 with the middle of the third-stage liquid storage tank 1g, and the third-stage fourth pipeline 26 connects the gas phase outlet of the third-stage reboiler 7 with the cavity section 1d; one end of the second branch pipe 29 is connected to the third-stage second pipeline 24, and the concentration of the organic waste liquid obtained after reboiler concentration in the third-stage reboiler unit is 70% to 80%. The organic waste liquid of this concentration is discharged from the bottom of the third-stage liquid storage tank 1g through the third-stage first pipeline 23, the third-stage second pipeline 24 and the second branch pipe 29. The third-stage first valve 35 is arranged on the third-stage second pipeline 24, and the third-stage first valve 35 is located between the connection between the second branch pipe 29 and the third-stage second pipeline 24 and the top of the third-stage reboiler 7.

[0042] The first-stage reboiler 5, the second-stage reboiler 6 and the third-stage reboiler 7 are all connected to the steam supply unit so as to respectively introduce steam into the reboilers of each stage, thereby providing heat for the reboilers of each stage.

[0043] The distillation unit also includes a condenser 2, a condensate tank 3 and a first delivery pump 37, and the sewage treatment unit includes a sewage tank 4. The top 1a of the distillation tower 1 is connected to the condenser 2, the condensate tank 3 and the first delivery pump 37 in sequence to form a closed loop, and the first delivery pump 37 is also connected to the sewage tank 4.

[0044] The steam condensate storage unit includes a steam condensate tank 39 and a second delivery pump 38, and the steam condensate tank 39 is connected to the second delivery pump 38. In addition, the first-stage reboiler 5, the second-stage reboiler 6 and the third-stage reboiler 7 are all connected to the steam condensate tank 39. The steam condensate tank 39 is used to store the steam condensate generated in each stage of the reboiler.

[0045] The following briefly describes the working process of the system for multi-stage reboiling and concentration of organic waste liquid in this embodiment:

[0046] The first liquid level control valve 30 is started, and the organic waste liquid with a concentration of 10% to 25% enters the first-stage liquid storage tank 1e through the organic waste liquid inlet pipe 14. The first-stage first valve 33 is opened, so that the organic waste liquid enters the top of the first-stage reboiler 5 from the bottom of the first-stage liquid storage tank 1e through the first-stage first pipeline 15, the first-stage discharge pump 8 and the first-stage second pipeline 16. The gas generated by heating in the first-stage reboiler 5 enters the distillation tank from the gas phase outlet on the side of the first-stage reboiler 5 through the first-stage fourth pipeline 18. In tower 1, the waste liquid concentrated by the first-stage reboiler 5 (the first-stage reboiler 5 can evaporate the low-boiling-point water therein, thereby increasing the concentration of the waste liquid entering the first-stage liquid storage tank 1e) enters the first-stage liquid storage tank 1e from the bottom of the first-stage reboiler 5 (and will be mixed with the organic waste liquid with a concentration of 10% to 25% introduced from the organic waste liquid inlet pipe 14), and the concentration of the organic waste liquid in the first-stage liquid storage tank 1e after concentration (the concentration after mixing) is increased to 30% to 40%.

[0047] Start the first-stage second liquid level control valve 31, open the second-stage first valve 34, and the organic waste liquid with a concentration of 30% to 40% in the first-stage liquid storage tank 1e flows from the bottom of the first-stage liquid storage tank 1e through the first-stage first pipeline 15, the first-stage discharge pump 8, the first-stage second pipeline 16 and the first-stage first branch pipe 27 to the second-stage liquid storage tank 1f, and then from the bottom of the second-stage liquid storage tank 1f through the second-stage first pipeline 19, the second-stage discharge pump 9 and the second-stage second pipeline 20 into the top of the second-stage reboiler 6. The gas generated by heating in the second-stage reboiler 6 is discharged from the second-stage reboiler 6 by the second-stage reboiler 6. The gas phase outlet on the side of 6 enters the distillation tower 1 through the second-stage fourth pipeline 22, and the waste liquid after being concentrated by the second-stage reboiler 6 (the second-stage reboiler 6 can evaporate the low-boiling point water therein, thereby increasing the concentration of the waste liquid entering the second-stage liquid storage tank 1f again) enters the second-stage liquid storage tank 1f from the bottom of the second-stage reboiler 6 (and will be mixed with the organic waste liquid with a concentration of 30%~40% directly introduced from the first-stage liquid storage tank 1e), and the concentration of the organic waste liquid in the second-stage liquid storage tank 1f after concentration (the concentration after mixing) is increased to 45%~50%.

[0048] Start the second-stage second liquid level control valve 32, open the third-stage first valve 35, and the organic waste liquid with a concentration of 45% to 50% in the second-stage liquid storage tank 1f flows from the bottom of the second-stage liquid storage tank 1f through the second-stage first pipeline 19, the second-stage discharge pump 9, the second-stage second pipeline 20 and the second-stage first branch pipe 28 to the third-stage liquid storage tank 1g, and then enters the top of the third-stage reboiler 7 from the bottom of the third-stage liquid storage tank 1g through the third-stage first pipeline 23, the third-stage discharge pump 10 and the third-stage second pipeline 24. The gas generated by heating in the third-stage reboiler 7 enters the distillation tower 1 through the gas phase outlet on the side of the third-stage reboiler 7 through the third-stage fourth pipeline 26, and is concentrated by the third-stage reboiler 7 (the third-stage reboiler 7 can evaporate the low-boiling-point water therein, thereby allowing the gas entering the third The waste liquid after the concentration is increased again in the third-stage liquid storage tank 1g enters the third-stage liquid storage tank 1g from the bottom of the third-stage reboiler 7 (it will be mixed with the organic waste liquid with a concentration of 45%~50% directly introduced from the second-stage liquid storage tank 1f), and the concentration of the organic waste liquid in the third-stage liquid storage tank 1g after concentration (the concentration after mixing) is increased to 70%~80%. At this time, the second valve 36 is opened, and the organic waste liquid with a concentration of 70%~80% in the third-stage liquid storage tank 1g is discharged from the bottom of the third-stage liquid storage tank 1g through the third-stage first pipeline 23, the third-stage discharge pump 10, the third-stage second pipeline 24 and the second branch pipe 29 (it can flow to the next distillation equipment to reprocess the high-concentration organic waste liquid treated by the organic waste liquid multi-stage reboiling and concentration system of the present invention). The low-boiling-point water in the waste liquid is evaporated step by step through the first-stage reboiler 5, the second-stage reboiler 6 and the third-stage reboiler, so that the concentration of the waste liquid entering the liquid storage tanks at each stage in sequence gradually increases.

[0049] The gas entering the distillation tower 1 from the gas phase outlets on the sides of the first-stage reboiler 5, the second-stage reboiler 6 and the third-stage reboiler 7 gradually rises from the bottom of the tower body. The liquid produced by the gas-liquid exchange condensation during the rising process will flow back to the first-stage liquid storage tank 1e, and the remaining gas will directly run out from the top 1a of the distillation tower 1, and after being cooled by the condenser 2, enter the condensate tank 3 for storage. A part of the condensate in the condensate tank 3 flows back to the top 1a of the distillation tower 1 through the first delivery pump 37; the excess condensate in the condensate tank 3 flows to the sewage pool 4 through the first delivery pump 37, so as to be biochemically treated in the sewage pool 4. When the content of organic solvent in the condensate at the top 1a of the tower is greater than 1000ppm, the flow rate of the condensate flowing back to the top 1a of the tower is increased; when the content of organic solvent in the condensate at the top 1a of the tower is less than 1000ppm, the flow rate of the condensate flowing back to the top 1a of the tower is reduced.

[0050] The steam condensate in the first-stage reboiler 5 , the second-stage reboiler 6 and the third-stage reboiler 7 directly enters the steam condensate tank 39 for storage and is then discharged through the second delivery pump 38 .

[0051] The system for multi-stage reboiling and concentrating organic waste liquid of the present invention can concentrate the waste liquid concentration to 30%-40% through the first stage of reboiling and concentration when the concentration of the organic waste liquid is 10%-25%, can concentrate the waste liquid concentration to 45%-50% through the second stage of reboiling and concentration, and can concentrate the waste liquid concentration to 70%-80% through the third stage of reboiling and concentration. In the case of only one distillation tower 1, the number of equipment can be effectively reduced, the equipment footprint can be reduced, and the investment cost of the enterprise can be greatly reduced.

[0052] Example 2 Method for multi-stage reboiling and concentration of organic waste liquid

[0053] Based on the system for multi-stage reboiling and concentrating organic waste liquid in Example 1, this embodiment provides a method for multi-stage reboiling and concentrating organic waste liquid, comprising the following steps:

[0054] The organic waste liquid is transported to the first-stage liquid storage tank and then sequentially reboiled and concentrated by the first-stage reboiler unit to the n-stage reboiler unit, and the liquid treated by the n-stage reboiler unit is discharged from the n-stage liquid storage tank;

[0055] The gas produced during the treatment process of each reboiler unit enters the distillation tower;

[0056] Part of the gas in the distillation tower is condensed during the rising process in the distillation tower due to gas-liquid exchange, and the liquid generated is returned to the first-stage liquid storage tank;

[0057] The remaining part of the gas in the distillation tower flows out from the top of the tower, and the condensate produced after condensation flows back to the top of the distillation tower and / or enters the sewage treatment unit for treatment.

[0058] In this embodiment, n is three, and a method for multi-stage reboiling and concentrating organic waste liquid is introduced in detail, including the following steps:

[0059] Step 1: First stage reboiling and concentration

[0060] The organic waste liquid with a concentration of 10% to 25% enters the first-stage liquid storage tank 1e from the organic waste liquid inlet pipe 14, and enters the top of the first-stage reboiler 5 from the bottom of the first-stage liquid storage tank 1e through the first-stage first pipeline 15, the first-stage discharge pump 8 and the first-stage second pipeline 16. The waste liquid concentrated by the first-stage reboiler 5 enters the first-stage liquid storage tank 1e from the bottom of the first-stage reboiler 5. The concentration of the organic waste liquid in the first-stage liquid storage tank 1e after concentration is increased to 30% to 40%. The waste liquid with this concentration flows from the bottom of the first-stage liquid storage tank 1e through the first-stage first pipeline 15, the first-stage discharge pump 8, the first-stage second pipeline 16 and the first-stage first branch pipe 27 to the second-stage liquid storage tank 1f.

[0061] The gas generated by heating in the first-stage reboiler 5 enters the distillation tower 1 through the gas phase outlet on the side of the first-stage reboiler 5 through the first-stage fourth pipeline 18. The gas in the distillation tower 1 gradually rises from the bottom of the tower body. The liquid generated by the gas-liquid exchange condensation during the rising process will flow back to the first-stage liquid storage tank 1e. The remaining gas will directly run out from the top 1a of the distillation tower 1, and after being cooled by the condenser 2, it will enter the condensate tank 3 for storage. A part of the condensate in the condensate tank 3 will flow back to the top 1a of the distillation tower 1 through the first delivery pump 37; the excess condensate in the condensate tank 3 will flow to the sewage pool 4 through the first delivery pump 37 to be biochemically treated in the sewage pool 4. The steam condensate in the first-stage reboiler 5 will directly enter the steam condensate tank 39 for storage, and then be discharged through the second delivery pump 38.

[0062] Step 2: Second stage reboiling and concentration

[0063] The waste liquid with a concentration of 30% to 40% enters the top of the second-stage reboiler 6 from the bottom of the second-stage liquid storage tank 1f through the second-stage first pipeline 19, the second-stage discharge pump 9 and the second-stage second pipeline 20. The waste liquid concentrated by the second-stage reboiler 6 enters the second-stage liquid storage tank 1f from the bottom of the second-stage reboiler 6. The concentration of the organic waste liquid in the second-stage liquid storage tank 1f after concentration is increased to 45% to 50%. The waste liquid with this concentration flows from the bottom of the second-stage liquid storage tank 1f through the second-stage first pipeline 19, the second-stage discharge pump 9, the second-stage second pipeline 20 and the second-stage first branch pipe 28 to the third-stage liquid storage tank 1g.

[0064] The gas generated by heating in the second-stage reboiler 6 enters the distillation tower 1 through the gas phase outlet on the side of the second-stage reboiler 6 via the second-stage fourth pipeline 22, and is combined with the gas entering the distillation tower 1 through the first-stage fourth pipeline 18 from the gas phase outlet on the side of the first-stage reboiler 5. The processing process is the same as step one and will not be repeated here.

[0065] The steam condensate in the second-stage reboiler 6 directly enters the steam condensate tank 39 for storage, and is then discharged through the second delivery pump 38 .

[0066] Step 3: Third-stage reboiling and concentration

[0067] The waste liquid with a concentration of 45% to 50% enters the top of the third-stage reboiler 7 from the bottom of the third-stage liquid storage tank 1g through the third-stage first pipeline 23, the third-stage discharge pump 10 and the third-stage second pipeline 24. The waste liquid concentrated by the third-stage reboiler 7 enters the third-stage liquid storage tank 1g from the bottom of the third-stage reboiler 7. The concentration of the organic waste liquid in the third-stage liquid storage tank 1g after concentration is increased to 70% to 80%.

[0068] The gas generated by heating in the third-stage reboiler 7 enters the distillation tower 1 through the gas phase outlet on the side of the third-stage reboiler 7 via the third-stage fourth pipeline 26, and is combined with the gas entering the distillation tower 1 through the gas phase outlet on the side of the first-stage reboiler 5 via the first-stage fourth pipeline 18 and the gas entering the distillation tower 1 through the gas phase outlet on the side of the second-stage reboiler 6 via the second-stage fourth pipeline 22. The processing process is the same as step one and will not be repeated here.

[0069] The steam condensate in the third-stage reboiler 7 directly enters the steam condensate tank 39 for storage, and then is discharged through the second delivery pump 38 .

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for multi-stage reboiling and concentration of organic waste liquid, characterized in that: The invention comprises a distillation unit, a steam condensate storage unit, a sewage treatment unit and n-stage reboiler units connected in series, wherein the distillation unit is connected to the sewage treatment unit, the distillation unit comprises a distillation tower, the distillation tower comprises a tower kettle and a tower body, the tower kettle of the distillation tower has n-stage mutually isolated liquid storage tanks, the first-stage liquid storage tank is connected to the tower body and the second-stage liquid storage tank to the n-th-stage liquid storage tank are isolated from the tower body, wherein n is a positive integer greater than or equal to 3; each stage of the reboiler unit is connected to the tower body and the steam condensate storage unit, the first-stage liquid storage tank is connected to the tower body and the steam condensate storage unit, the first-stage liquid storage tank is connected to the tower body and the steam condensate storage unit, the first-stage liquid storage tank is connected to the tower body and the steam condensate storage unit, the first-stage liquid storage tank is connected to the tower body and the steam condensate storage unit, the steam condensate storage tank is connected to the tower body and the sewage treatment unit, the sewage treatment unit comprises a distillation tower, the distillation tower comprises a tower kettle and a tower body, the tower kettle of the distillation tower has n-stage mutually isolated liquid storage tanks, the first-stage liquid storage tank is connected to the tower body and the steam condensate storage unit, the sewage treatment unit is connected to ... is connected to the sewage treatment unit, the sewage treatment unit is connected to the sewage treatment unit, the sewage treatment unit is connected to the sewage treatment unit, the sewage treatment unit is connected to the sewage treatment unit, the sewage treatment unit is connected to the sewage treatment unit, the sewage treatment unit is connected to the sewage treatment unit, the sewage treatment unit The tank is provided with an organic waste liquid inlet pipe, the first-stage reboiler unit is connected to the first-stage liquid storage tank and the second-stage liquid storage tank, the second-stage reboiler unit is connected to the second-stage liquid storage tank and the third-stage liquid storage tank, and the n-stage reboiler unit is connected to the n-stage liquid storage tank. The organic waste liquid is discharged from the bottom of the n-stage liquid storage tank after multi-stage reboiler concentration; the volume of the liquid storage tank gradually decreases from the first stage to the n-stage, and the top surface of each stage of the liquid storage tank is located on the same plane, the top surface of the first-stage liquid storage tank has a through opening, and the top surfaces of the second-stage liquid storage tank to the n-stage liquid storage tank are commonly provided with a cover plate.

2. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 1, characterized in that: A liquid level meter is provided in each level of the liquid storage tank.

3. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 2, characterized in that: Each stage of the reboiler unit includes a reboiler, a discharge pump, a first pipeline, a second pipeline, and a third pipeline. The first pipeline connects the bottom of each stage of the liquid storage tank with the discharge pump, the second pipeline connects the discharge pump with the top of the reboiler, and the third pipeline connects the bottom of the reboiler with the middle of each stage of the liquid storage tank.

4. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 3, characterized in that: The first to n-1th reboiler units also include a first branch pipe, one end of which is connected to the second pipeline, and the first branch pipe connects the discharge pump of the n-2th reboiler unit and the liquid storage tank of the n-1th reboiler unit.

5. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 4, characterized in that: A first liquid level control valve is arranged on the organic waste liquid inlet pipe, a second liquid level control valve is arranged on each of the first branch pipes, the liquid level gauge of the first-stage liquid storage tank is connected to the first liquid level control valve, and the liquid level gauge of the n-1th stage liquid storage tank is connected to the second liquid level control valve in the n-2th stage reboiler unit.

6. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 5, characterized in that: When the liquid level height of the liquid level gauge is less than 1m, the first liquid level control valve and / or the second liquid level control valve is opened; when the liquid level height of the liquid level gauge is greater than 1.5m, the first liquid level control valve and / or the second liquid level control valve is closed.

7. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 6, characterized in that: The tower body includes a cavity section, a packing section and a tower top. The cavity section is located between the tower bottom and the packing section. The cavity section is connected to the first-stage liquid storage tank. A plurality of packing layers are evenly spaced in the packing section along its height direction, and a liquid distributor is provided above each packing layer.

8. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 7, characterized in that: Each stage of the reboiler unit further includes a fourth pipe, and each side of the reboiler has a gas phase outlet, and the fourth pipe is used to connect the gas phase outlet of the reboiler with the cavity section.

9. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 4, characterized in that: The n-stage reboiler unit also includes a second branch pipe, one end of which is connected to the second pipe of the n-stage reboiler unit. After being concentrated through multi-stage reboiler, the organic waste liquid is discharged from the bottom of the n-stage liquid storage tank through the first pipe, the second pipe and the second branch pipe of the n-stage reboiler unit.

10. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 9, characterized in that: A first valve is provided on each of the second pipelines, a second valve is provided on the second branch pipe, the first valves in the first-stage reboiler unit to the n-1th-stage reboiler unit are located between the connection between the first branch pipe and the second pipeline and the top of the reboiler, and the first valve in the nth-stage reboiler unit is located between the connection between the second branch pipe and the second pipeline and the top of the reboiler.

11. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 9, characterized in that: The concentration of the organic waste liquid entering the first-stage liquid storage tank through the organic waste liquid inlet pipe is 10%-25%, and the concentration of the organic waste liquid after reboiled and concentrated by the n-stage reboiler unit is 70%-80%.

12. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 7, characterized in that: The distillation unit also includes a condenser, a condensate tank and a first delivery pump. The top of the distillation tower is connected to the condenser, the condensate tank and the first delivery pump in sequence to form a closed loop. The first delivery pump is also connected to the sewage treatment unit.

13. The system for multi-stage reboiling and concentration of organic waste liquid according to claim 9, characterized in that: The steam condensate storage unit includes a steam condensate tank and a second delivery pump that are connected to each other. Each of the reboilers is connected to the steam condensate tank. The steam condensate tank is used to store the steam condensate generated in each of the reboilers.

14. A method for multi-stage reboiling and concentration of organic waste liquid according to the system for multi-stage reboiling and concentration of organic waste liquid according to any one of claims 1 to 13, characterized in that: The steps include: The organic waste liquid is transported to the first-stage liquid storage tank and then sequentially reboiled and concentrated by the first-stage reboiler unit to the n-stage reboiler unit, and the liquid treated by the n-stage reboiler unit is discharged from the n-stage liquid storage tank; The gas produced during the treatment process of each reboiler unit enters the distillation tower; Part of the gas in the distillation tower is condensed during the rising process in the distillation tower due to gas-liquid exchange, and the liquid generated is returned to the first-stage liquid storage tank; The remaining part of the gas in the distillation tower flows out from the top of the tower, and the condensate produced after condensation flows back to the top of the distillation tower and / or enters the sewage treatment unit for treatment.

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