Method and system for hydrogen production from organic wastewater with co-production of freshwater and complex carbon source

Abstract

The present invention relates to a method and system for hydrogen production from organic wastewater with co-production of freshwater and a complex carbon source. The system of the present invention comprises an organic-wastewater guiding-out unit, an oxidation treatment unit, and a water electrolysis and low-temperature distillation coupled integrated system, wherein the water electrolysis and low-temperature distillation coupled integrated system comprises an alkaline electrolytic cell unit, an oxygen separation and cooling unit, a hydrogen separation and cooling unit, a hydrogen purification and cooling unit, an alkaline-solution filtration and circulation unit and a wastewater-to-freshwater unit; the organic-wastewater guiding-out unit is used for supplying wastewater into the oxidation treatment unit; the oxidation treatment unit treats the wastewater into wastewater containing carboxylic acid or carboxylate, and the oxidation treatment unit is connected to the wastewater-to-freshwater unit; the wastewater-to-freshwater unit is used for producing freshwater and a complex carbon source; and an output end of the wastewater-to-freshwater unit is connected to the alkaline electrolytic cell unit, and freshwater in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of a direct current. The present invention involves a short technological process, occupies a small area and achieves a high product value and resource utilization of wastewater.

Description

Method and system for producing hydrogen from organic wastewater, co-producing fresh water and composite carbon source TECHNICAL FIELD

[0001] The present application relates to the technical field of indirect hydrogen production from wastewater, in particular, and more particularly to a method and system for producing hydrogen from organic wastewater, co-producing fresh water and composite carbon source. BACKGROUND

[0002] The existing treatment technology of chemical industrial wastewater is complex and diversified, and mostly needs to set up processes such as wastewater pretreatment, biochemical treatment, advanced treatment and brine treatment. After the high-salinity wastewater is concentrated and crystallized to recover water, the salt is landfilled as hazardous waste. The chemical industrial wastewater is only treated to meet the provincial or national discharge standards, and the treated wastewater cannot be reused and is discharged into the municipal sewage network or other places. At present, the treatment of industrial wastewater is mainly for discharge after treatment, and there is no much resource utilization of industrial wastewater. The above wastewater treatment process has the disadvantages of high energy consumption, high operation cost and certain negative impact on the environment. In addition, various treatment devices are connected through pipelines, and the overall land occupation is large, which is low in utilization rate of the plant area.

[0003] Hydrogen energy is considered as the most potential clean energy in the 21st century. At present, the proton exchange membrane water electrolysis technology (PEM) needs to use pure water as raw material, and the current single machine output is low and the cost is high; while the alkaline water electrolysis hydrogen production technology only needs to use fresh water as raw material, and is the most mature and most widely industrialized hydrogen production technology, occupying a dominant position. The Global Hydrogen Water Report released by the International Renewable Energy Agency (IRENA) shows that the current mainstream hydrogen production method needs fresh water, mainly concentrated in the processes of hydrogen production and cooling. About 32.2 liters of fresh water are needed to produce 1 kilogram of blue hydrogen. The amount of fresh water consumed by the alkaline water electrolysis hydrogen production process to produce 1 kilogram of green hydrogen is expected to be 22.3 liters. However, the global fresh water resources are extremely limited, which will undoubtedly exacerbate the problem of fresh water shortage.

[0004] The existing production of composite carbon source needs to go through the following steps:

[0005] 1. Raw material preparation: The main raw materials of composite carbon source are chemical products such as coal tar and petroleum tar, which need to be finely processed and selected to ensure that their quality meets the production requirements; 2. Mixing preparation: Mix different proportions of raw materials together and add appropriate amount of catalyst and additive, and fully stir and mix to form a uniform mixture; 3. Pyrolysis reaction: Put the mixture into a high-temperature reaction furnace and carry out pyrolysis reaction at high temperature. In this process, the raw materials decompose and release a large amount of gas to generate composite carbon source. The existing production technology of composite carbon source is also complex, and needs to consume chemical products for implementation. SUMMARY

[0006] According to the technical problems proposed above, a method and system for producing hydrogen, fresh water and composite carbon source from organic wastewater are provided. The present application can realize low-cost organic wastewater treatment, save the land area of wastewater treatment devices, and realize efficient production of hydrogen energy and composite carbon source and other high-value products.

[0007] The technical means adopted by the present application are as follows:

[0008] A system for producing hydrogen, fresh water and composite carbon source from organic wastewater comprises an organic wastewater leading-out unit, an oxidation treatment unit and an electrolytic water coupling low-temperature distillation integrated system. The oxidation treatment unit is connected with an oxidant dosage adjusting module for controlling the dosage of oxidant entering the oxidation treatment unit, so that the wastewater entering the electrolytic water coupling low-temperature distillation integrated system contains carboxylic acid or carboxylic acid salt. The electrolytic water coupling low-temperature distillation integrated system comprises an alkaline electrolytic cell unit, an oxygen separation cooling unit, a hydrogen separation cooling unit, a hydrogen purification cooling unit, an alkali solution filtration and circulation unit and a wastewater fresh water production unit. The organic wastewater leading-out unit is used to supply organic wastewater to the oxidation treatment unit. The oxidation treatment unit and the electrolytic water coupling low-temperature distillation integrated system are connected, the wastewater fresh water production unit is used to heat the wastewater, remove impurities by steam and produce fresh water after condensation, and the composite carbon source after the fresh water is removed is collected by a composite carbon source collecting port arranged at the bottom of the wastewater fresh water production unit; the output end of the wastewater fresh water production unit is connected with the alkaline electrolytic cell unit, the fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen enters the hydrogen separation cooling unit and the oxygen enters the oxygen separation cooling unit; the hydrogen purification cooling unit is used to complete the purification of hydrogen, and the alkali solution filtration and circulation unit is used to complete the forced circulation of alkali solution in the alkaline electrolytic cell unit, the hydrogen separation cooling unit and the oxygen separation cooling unit.

[0009] Further, the wastewater containing carboxylic acid or carboxylic acid salt enters the wastewater fresh water production unit or enters the hydrogen separation cooling unit or the oxygen separation cooling unit.

[0010] Further, the oxidation treatment unit is connected with an oxidant adding unit, and the oxidation treatment unit is provided with an oxidant, so that after the oxidant is added to the oxidation treatment unit, part of the organic wastewater output by the oxidation treatment unit is oxidized into CO2, and the other part becomes the wastewater containing carboxylic acid or carboxylic acid salt entering the electrolytic water coupling low-temperature distillation integrated system.

[0011] Further, the hydrogen outlet of the alkaline electrolytic cell unit is connected with the hydrogen separation and cooling unit, the oxygen outlet of the alkaline electrolytic cell unit is connected with the oxygen separation and cooling unit, the alkali inlet of the alkaline electrolytic cell unit is connected with the wastewater into fresh water unit, the oxygen separation and cooling unit separates oxygen and alkali by a gas-liquid separation method, the hydrogen separation and cooling unit separates hydrogen and alkali by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation and cooling unit is connected with the hydrogen purification and cooling unit, the alkali outlet of the oxygen separation and cooling unit and the alkali outlet of the hydrogen separation and cooling unit are connected with the alkali filtration and circulation unit to provide high-temperature alkali to be cooled, and the fresh water outlet of the wastewater into fresh water unit is connected with the hydrogen separation and cooling unit.

[0012] Further, the gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation and cooling unit, the organic wastewater part output by the oxidation treatment unit is oxidized into CO2, and another part becomes the wastewater containing carboxylic acid or carboxylic acid salt entering the electrolytic water coupled low-temperature distillation integrated system.

[0013] Further, the wastewater into fresh water unit comprises a device cylinder, a vacuum pumping system, a condenser, a water receiving plate and a wire mesh separator. The device cylinder is provided with a vacuum pumping system connecting port, a wastewater inlet, a composite carbon source collecting port, a fresh water outlet and an alkali circulation pipe. The vacuum pumping system connecting port is connected with the vacuum pumping system, the wastewater inlet is connected with the organic wastewater leading-out unit or the oxidation treatment unit or the oxygen separation and cooling unit / hydrogen separation and cooling unit. The composite carbon source collecting port is used for collecting the composite carbon source. The alkali circulation pipe is used for heat exchange between the high-temperature alkali and the wastewater, so as to reduce the alkali temperature and make the wastewater evaporate into water vapor at the evaporation temperature. The water vapor is condensed by the condenser. The water receiving plate is used for receiving condensed water drops, and the output end thereof is connected with the fresh water outlet. The wire mesh separator is arranged in the device cylinder and is used for separating larger liquid drops and impurities in the water vapor.

[0014] Further, the organic wastewater into fresh water unit is further connected with a fresh water storage unit for storing excess fresh water.

[0015] The application further discloses a method for producing hydrogen, fresh water and composite carbon source from organic wastewater based on the above system, which comprises the following steps:

[0016] S1, based on the basic information of the wastewater to be treated, confirming the oxidation treatment mode of oxygen internal circulation or the oxidation treatment mode of external oxidation agent; controlling the dosage of the oxidation agent into the oxidation treatment unit by the oxidation agent dosage adjusting module, so as to make the wastewater entering the electrolytic water coupled low-temperature distillation integrated system contain carboxylic acid or carboxylic acid salt;

[0017] S2, connecting the electrolytic water coupled low-temperature distillation integrated system with the organic wastewater leading-out unit, and starting the production of hydrogen and fresh water from chemical wastewater, wherein,

[0018] The organic wastewater leading-out unit directly transports the organic wastewater containing carboxylic acid or carboxylic acid salt to the wastewater fresh water production unit for fresh water production, composite carbon source separation, or after the wastewater passes through the oxygen separation cooling unit and the hydrogen separation cooling unit, the wastewater enters the wastewater fresh water production unit, and the wastewater can assist in cooling in the oxygen separation cooling unit and the hydrogen separation cooling unit;

[0019] The fresh water in the alkaline electrolysis cell unit is decomposed into hydrogen and oxygen under the action of direct current;

[0020] The oxygen outlet of the alkaline electrolysis cell unit transports oxygen and alkali liquor to the oxygen separation cooling unit for gas-liquid separation, and when the oxidation treatment mode of oxygen internal circulation is adopted, the oxygen is returned to the oxidation treatment unit to participate in the reaction;

[0021] The hydrogen outlet of the alkaline electrolysis cell unit transports hydrogen and alkali liquor to the hydrogen separation cooling unit for gas-liquid separation, and after preliminary purification, the hydrogen and a small amount of water enter the hydrogen purification cooling unit for further purification to a hydrogen content of 99.999%, and the hydrogen is finally supplied to the user or stored;

[0022] The alkali liquor filtering and circulating unit extracts alkali liquor from the oxygen separation cooling unit and the hydrogen separation cooling unit, cools the alkali liquor through the wastewater fresh water production unit, and finally transports the alkali liquor to the alkaline electrolysis cell unit to complete the cooling and forced circulation of the alkali liquor;

[0023] The heat emitted by the alkali liquor when cooled in the wastewater fresh water production unit is used to heat the wastewater under negative pressure to produce fresh water, and the produced fresh water is transported to the hydrogen separation module to supplement the raw material fresh water for electrolysis, and also assists in realizing hydrogen washing and cooling.

[0024] Compared with the prior art, the present application has the following advantages: the traditional wastewater treatment process has a large occupied area and a complex process flow. The present application directly introduces the organic wastewater after oxidation treatment into an electrolysis water coupled low-temperature distillation integrated system, and the process flow is short and the occupied area is small. The electrolysis water coupled low-temperature distillation integrated system of the present application uses the alkali liquor to be cooled to heat the wastewater under negative pressure, the alkali liquor is cooled, and at the same time, the heat emitted by the alkali liquor when cooled is also utilized. The fresh water produced by the wastewater fresh water production unit is supplemented to the alkaline electrolysis cell unit as the electrolysis water raw material, which relieves the dependence on fresh water resources, and the separated composite carbon source is suitable for industrial wastewater and municipal sewage denitrification, which can completely replace traditional carbon sources such as methanol, glucose and sodium acetate, and has high safety. The chemical wastewater is finally completely changed into high-concentration hydrogen, oxygen, fresh water and composite carbon source, and the generated fresh water is much better than the traditional wastewater that meets the discharge standard, and the resource utilization of the wastewater is realized. In addition, the oxygen generated in the system of the present application can also be used as the source of oxidation treatment to complete the internal circulation of the system, and the final products are effectively utilized. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0026] Fig. 1 is a whole flow chart of the system for producing hydrogen, co-producing fresh water and composite carbon source from organic chemical wastewater according to the present application.

[0027] Fig. 2 is a flow chart of scheme 1 in the embodiment of the present application.

[0028] Fig. 3 is a flow chart of scheme 2 in the embodiment of the present application. DETAILED DESCRIPTION

[0029] It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0031] It should be noted that the terms used herein are only for the purpose of describing the specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0032] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all suitable modifications and equivalents can be resorted to falling within the scope of the application. Unless otherwise indicated herein, the contents of all patents, patent applications, publications, and test methods cited herein are hereby incorporated by reference in their entirety for all purposes.

[0033] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "up", "down", "left", "right", "lateral", "vertical", "horizontal", "top", "bottom", and the like are generally based on the orientation or positional relationships shown in the drawings, and are merely intended to facilitate the description and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore cannot be construed as limiting the scope of protection of the present application. The orientation terms "inner", "outer" refer to the inner and outer relative to the contour of the components themselves.

[0034] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper", and the like can be used herein to describe the spatial positional relationship of one device or feature with respect to other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device as described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" the other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0035] In addition, it should be noted that the use of the terms "first", "second", and the like do not have a special meaning, and are merely used to distinguish corresponding parts, and therefore cannot be construed as limiting the scope of protection of the present application.

[0036] As shown in FIG. 1, the present application discloses a system for hydrogen production, fresh water and composite carbon source co-production from organic wastewater, comprising: an organic wastewater leading unit, an oxidation treatment unit and an electrolytic water coupled low-temperature distillation integrated system, wherein the oxidation treatment unit is connected with an oxidant dosage adjusting module for controlling the dosage of oxidant entering the oxidation treatment unit, specifically, as shown in FIG. 2 and FIG. 3, the system can comprise an oxygen amount adjusting module and / or an oxidant dosage adjusting module, so that the wastewater entering the electrolytic water coupled low-temperature distillation integrated system contains carboxylic acid or carboxylic acid salt, and the electrolytic water coupled low-temperature distillation integrated system comprises an alkaline electrolytic cell, an oxygen separation and cooling unit, a hydrogen separation and cooling unit, a hydrogen purification and cooling unit, an alkali solution filtration and circulation unit and a wastewater fresh water production unit. The organic wastewater leading unit is used for supplying organic wastewater to the oxidation treatment unit, and mainly comprises a water pump, a check valve, a flow meter and the like. The oxidation treatment unit and the electrolytic water coupled low-temperature distillation integrated system are connected. The wastewater fresh water production unit is used for heating the wastewater, removing impurities by steam, and producing fresh water after condensation, and the composite carbon source after the fresh water is removed is collected by a composite carbon source collecting port arranged at the bottom of the wastewater fresh water production unit. The output end of the wastewater fresh water production unit is connected with the alkaline electrolytic cell, and the produced fresh water is transported to the alkaline electrolytic cell, and the excess fresh water is discharged and stored. The fresh water in the alkaline electrolytic cell is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen enters the hydrogen separation and cooling unit, and the oxygen enters the oxygen separation and cooling unit. The hydrogen purification and cooling unit is used for completing the purification of hydrogen, and the alkali solution filtration and circulation unit is used for completing the forced circulation of alkali solution in the alkaline electrolytic cell, the hydrogen separation and cooling unit and the oxygen separation and cooling unit. The fresh water co-produced by the wastewater fresh water production unit is output through a fresh water recovery port. The oxygen separation and cooling unit mainly comprises an oxygen gravity type horizontal separator, a scrubber, a condenser and the like. The hydrogen separation and cooling unit mainly comprises a hydrogen gravity type horizontal separator, a scrubber, a condenser and the like. The hydrogen purification and cooling unit mainly comprises a deoxygenation tower, a drying tower, a condenser, a gas-liquid separator and the like. The alkali solution filtration and circulation unit mainly comprises an alkali solution circulating pump, a check valve, a flow meter and the like.

[0037] In the figure, the baseline is the electrolytic water coupled low-temperature distillation integrated system.

[0038] The hydrogen purification and cooling unit removes trace oxygen and trace water from the entering hydrogen by catalytic reaction, and removes water and other impurities by molecular sieve adsorption principle, and finally purifies the hydrogen to 99.999%.

[0039] In one embodiment, the fresh water in the alkaline electrolytic cell is decomposed into one part of hydrogen and 1 / 2 part of oxygen under the action of direct current, and the direct current can be directly connected or the power supply can be completed by converting alternating current into direct current.

[0040] As an optional embodiment, the oxidation treatment unit of the present application adopts advanced oxidation technology, including Fenton oxidation, photocatalytic oxidation, ozone catalytic oxidation, electrochemical oxidation, ultrasonic oxidation, supercritical water oxidation, etc., to oxidize and decompose organic matter into small molecules, until degradation into carbon dioxide CO2 and wastewater containing inorganic salts.

[0041] Further, the wastewater enters the wastewater fresh water production unit or enters the hydrogen separation cooling unit or the oxygen separation cooling unit.

[0042] Further, the oxidation treatment unit is connected with an oxidant adding unit, mainly including a reagent storage tank, a reagent filling metering pump, a check valve, a flow meter, etc. The oxidant adding unit is provided with an oxidant, so that after the oxidant is added to the oxidation treatment unit, part of the organic wastewater output by the oxidation treatment unit is oxidized into CO2, and the other part becomes wastewater containing carboxylic acid or carboxylic acid salt entering the electrolytic water coupled low-temperature distillation integrated system.

[0043] Further, the hydrogen outlet of the alkaline electrolysis tank unit is connected with the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolysis tank unit is connected with the oxygen separation cooling unit, the alkali inlet of the alkaline electrolysis tank unit is connected with the wastewater fresh water production unit, the oxygen separation cooling unit separates oxygen and alkali by a gas-liquid separation method, the hydrogen separation cooling unit separates hydrogen and alkali by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation cooling unit is connected with the hydrogen purification cooling unit, the alkali outlet of the oxygen separation cooling unit and the alkali outlet of the hydrogen separation cooling unit are connected with the alkali filtration circulation unit to provide high-temperature alkali to be cooled, and the fresh water outlet of the wastewater fresh water production unit is connected with the hydrogen separation cooling unit.

[0044] Further, the gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation cooling unit, part of the organic wastewater output by the oxidation treatment unit is oxidized into CO2, and the other part becomes organic wastewater containing carboxylic acid or carboxylic acid salt entering the electrolytic water coupled low-temperature distillation integrated system.

[0045] Further, the wastewater into fresh water unit comprises a device cylinder, a vacuum system (including but not limited to a vacuum pump), a condenser, a water receiving plate, and a wire mesh separator, the device cylinder is provided with a vacuum system connecting port, a wastewater inlet, a composite carbon source collecting port, a fresh water outlet, and an alkali liquor circulating pipe, the vacuum system connecting port is connected with the vacuum system, the wastewater inlet is connected with the organic wastewater leading-out unit or the oxidation treatment unit or the oxygen separation cooling unit / hydrogen separation cooling unit, the composite carbon source collecting port is used for collecting the composite carbon source, and the alkali liquor circulating pipe is used for heat exchange between high-temperature alkali liquor and wastewater, so as to reduce the alkali liquor temperature and make the wastewater evaporate into water vapor at evaporation temperature, the water vapor is condensed by the condenser, the water receiving plate is used for receiving condensed water drops, and the output end of the water receiving plate is connected with the fresh water outlet, and the wire mesh separator is arranged in the device cylinder and used for separating large droplets and impurities in the water vapor.

[0046] Further, the organic wastewater into fresh water unit is further connected with a fresh water storage unit, including but not limited to a water storage pool and a water storage tank, and is used for storing excess fresh water.

[0047] The application further discloses a method for producing hydrogen and fresh water and composite carbon source from organic wastewater based on the system, and the method comprises the following steps.

[0048] S1, confirming the composition of wastewater, based on whether the wastewater source is organic wastewater or inorganic wastewater, confirming whether the oxidation treatment unit is arranged or not, if the wastewater is organic wastewater, entering step S2, if the wastewater is inorganic wastewater, entering step S3;

[0049] S2, based on the basic information of the wastewater to be treated, confirming the form of the oxidation treatment unit, that is, adopting an oxidation treatment mode of oxygen internal circulation or an oxidation treatment mode of external oxidant.

[0050] In the oxidation treatment unit, organic acid and carboxylic acid are obtained through hydrolysis and acidification reaction, and then the substances are further hydrolyzed to form small molecular compounds such as monosaccharide, disaccharide and polysaccharide, and then the composite carbon source for subsequent separation is formed.

[0051] S3, connecting the electrolytic water coupling low-temperature distillation integrated system with the wastewater leading-out unit or the oxidation treatment unit, and starting the production of hydrogen and fresh water from chemical wastewater.

[0052] The wastewater leading-out unit directly or after oxidation of the wastewater leading-out unit, transports the wastewater to the wastewater into fresh water unit to produce fresh water and separate concentrated brine, or the wastewater after the wastewater leading-out unit enters the wastewater into fresh water unit, and the wastewater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit.

[0053] The fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current.

[0054] The oxygen outlet of the alkaline electrolyzer unit transports oxygen and alkali liquor into the oxygen separation and cooling unit for gas-liquid separation, and when the oxidation treatment mode of oxygen internal circulation is adopted, the oxygen is returned to the oxidation treatment unit to participate in the reaction; the excess oxygen is exhausted;

[0055] The hydrogen outlet of the alkaline electrolyzer unit transports hydrogen and alkali liquor into the hydrogen separation and cooling unit for gas-liquid separation, and the hydrogen and a small amount of water after preliminary purification enter the hydrogen purification and cooling unit for further purification to a hydrogen content of ≥99.99%, and the hydrogen is finally supplied to the user or stored;

[0056] The alkali liquor filtration and circulation unit extracts alkali liquor from the oxygen separation and cooling unit and the hydrogen separation and cooling unit, and after cooling by the wastewater to fresh water unit, the alkali liquor is finally transported to the alkaline electrolyzer unit to complete the cooling and forced circulation of the alkali liquor;

[0057] The heat emitted by the alkali liquor when cooled in the wastewater to fresh water unit is used to heat the wastewater under negative pressure to produce fresh water, and the produced fresh water is transported to the hydrogen separation module to supplement the raw material fresh water for electrolysis, and also to assist in realizing hydrogen gas washing and cooling.

[0058] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A system for hydrogen production, fresh water production and composite carbon source production from organic wastewater, characterized in that, The system comprises an organic wastewater leading-out unit, an oxidation treatment unit and an electrolytic water coupled low-temperature distillation integrated system, The oxidation treatment unit is connected with an oxidant dosage adjusting module for controlling the dosage of oxidant into the oxidation treatment unit, so that the wastewater into the electrolytic water coupled low-temperature distillation integrated system contains carboxylic acid or carboxylic acid salt. The electrolytic water coupled low-temperature distillation integrated system comprises an alkaline electrolytic cell unit, an oxygen separation and cooling unit, a hydrogen separation and cooling unit, a hydrogen purification and cooling unit, an alkali solution filtering and circulating unit and a wastewater fresh water making unit. The organic wastewater leading-out unit is used for supplying organic wastewater to the oxidation treatment unit. The oxidation treatment unit and the electrolytic water coupled low-temperature distillation integrated system are connected, the wastewater fresh water making unit is used for heating the wastewater, removing impurities by steam, and condensing to produce fresh water and obtain a composite carbon source after the fresh water is removed, the composite carbon source is collected by a composite carbon source collecting port arranged at the bottom of the wastewater fresh water making unit. The output end of the wastewater fresh water making unit is connected with the alkaline electrolytic cell unit, the fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current, the hydrogen and the alkali solution enter the hydrogen separation and cooling unit, the oxygen and the alkali solution enter the oxygen separation and cooling unit, the hydrogen purification and cooling unit is used for completing the purification of hydrogen, and the alkali solution filtering and circulating unit is used for completing the forced circulation of the alkali solution in the alkaline electrolytic cell unit, the hydrogen separation and cooling unit and the oxygen separation and cooling unit.

2. The system for hydrogen production coupled with fresh water and composite carbon source production from organic wastewater according to claim 1, characterized in that, The organic wastewater containing carboxylic acid or carboxylic acid salt enters the wastewater fresh water making unit or enters the hydrogen separation and cooling unit and the oxygen separation and cooling unit. 3.The system for hydrogen production coupled with fresh water and composite carbon source production from organic wastewater according to claim 1, wherein, The oxidation treatment unit is also connected with an oxidant adding unit, the oxidant adding unit is provided with an oxidant, so that the organic wastewater output from the oxidation treatment unit is partly oxidized into CO2 and the other part becomes the wastewater containing carboxylic acid or carboxylic acid salt into the electrolytic water coupled low-temperature distillation integrated system.

4. The system for hydrogen production coupled with fresh water and composite carbon source production from organic wastewater according to claim 1, characterized in that, The hydrogen outlet of the alkaline electrolytic cell unit is connected with the hydrogen separation and cooling unit, the oxygen outlet of the alkaline electrolytic cell unit is connected with the oxygen separation and cooling unit, the alkali solution inlet of the alkaline electrolytic cell unit is connected with the wastewater fresh water making unit, the oxygen separation and cooling unit separates oxygen and alkali solution by a gas-liquid separation method, the hydrogen separation and cooling unit separates hydrogen and alkali solution by a gas-liquid separation method, the hydrogen outlet of the hydrogen separation and cooling unit is connected with the hydrogen purification and cooling unit, the alkali solution outlet of the oxygen separation and cooling unit and the alkali solution outlet of the hydrogen separation and cooling unit are connected with the alkali solution filtering and circulating unit to provide high-temperature alkali solution to be cooled, and the fresh water outlet of the wastewater fresh water making unit is connected with the hydrogen separation and cooling unit.

5. The system for hydrogen production coupled with fresh water and composite carbon source production from organic wastewater according to claim 1, wherein, The gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation and cooling unit, the organic wastewater output from the oxidation treatment unit is partly oxidized into CO2 and the other part becomes the organic wastewater containing carboxylic acid or carboxylic acid salt into the electrolytic water coupled low-temperature distillation integrated system. 6.The system for co-producing hydrogen, fresh water and composite carbon source from organic wastewater according to claim 1, wherein, The wastewater fresh water production unit comprises a device cylinder, a vacuum extraction system, a condenser, a water receiving plate and a wire mesh separator. The device cylinder is provided with a vacuum extraction system connecting port, a wastewater inlet, a composite carbon source collecting port, a fresh water outlet and an alkali solution circulation pipe. The vacuum extraction system connecting port is connected with the vacuum extraction system. The wastewater inlet is connected with an organic wastewater leading-out unit, an oxidation treatment unit or an oxygen separation cooling unit / hydrogen separation cooling unit. The composite carbon source collecting port is used for collecting a composite carbon source. The alkali solution circulation pipe is used for heat exchange between high-temperature alkali solution and wastewater, so as to reduce the temperature of the alkali solution and make the wastewater evaporate into water vapor at evaporation temperature. The water vapor is condensed by the condenser. The water receiving plate is used for receiving condensed water drops. The output end of the water receiving plate is connected with the fresh water outlet. The wire mesh separator is arranged in the device cylinder and is used for separating large liquid drops and impurities in the water vapor. 7.The system for co-producing hydrogen, fresh water and composite carbon source from organic wastewater according to claim 1, wherein, The organic wastewater fresh water production unit is further connected with a fresh water storage unit, which is used for storing excess fresh water.

8. The method of hydrogen production coupled with fresh water and composite carbon source production from organic wastewater according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: S1. Based on the basic information of the wastewater to be treated, the form of the oxidation treatment unit is determined, that is, an oxidation treatment mode of internal oxygen circulation or an oxidation treatment mode of external oxidant is adopted. The dosage of the oxidant entering the oxidation treatment unit is controlled by the oxidant dosage adjusting module, so that the wastewater entering the electrolytic water coupled low-temperature distillation integrated system contains carboxylic acid or carboxylic acid salt. S2. The electrolytic water coupled low-temperature distillation integrated system is connected with the wastewater leading-out unit or the oxidation treatment unit. The chemical wastewater hydrogen co-production fresh water production is started. In the method, The organic wastewater containing carboxylic acid or carboxylic acid salt is directly delivered to the wastewater fresh water production unit for fresh water production and composite carbon source separation, or the wastewater after the oxygen separation cooling unit and the hydrogen separation cooling unit enters the wastewater fresh water production unit. The wastewater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit. The fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current. The oxygen outlet of the alkaline electrolytic cell unit delivers oxygen and alkali solution to the oxygen separation cooling unit for gas-liquid separation. When the oxidation treatment mode of internal oxygen circulation is adopted, the oxygen is returned to the oxidation treatment unit for reaction. The hydrogen outlet of the alkaline electrolytic cell unit delivers hydrogen and alkali solution to the hydrogen separation cooling unit for gas-liquid separation. The hydrogen and a small amount of water after preliminary purification enter the hydrogen purification cooling unit for further purification, so that the hydrogen content is 99.999%. The hydrogen is finally supplied to the user or stored. The alkali solution filtering and circulating unit extracts the alkali solution in the oxygen separation cooling unit and the hydrogen separation cooling unit. After being cooled by the wastewater fresh water production unit, the alkali solution is finally delivered to the alkaline electrolytic cell unit, so that the cooling and forced circulation of the alkali solution are completed. The heat emitted by the alkali solution when being cooled by the wastewater fresh water production unit is used to heat the wastewater under negative pressure, so as to produce fresh water. The produced fresh water is delivered to the hydrogen separation module and is used to supplement the raw material fresh water for electrolysis and also to assist in realizing hydrogen washing and cooling.

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