Method and system for hydrogen production from chemical wastewater with co-production of freshwater

Abstract

The present invention relates to a method and system for hydrogen production from chemical wastewater with co-production of freshwater. The system of the present invention comprises a wastewater guiding-out 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 wastewater guiding-out unit is used for supplying wastewater into the water electrolysis and low-temperature distillation coupled integrated system; the wastewater-to-freshwater unit is used for heating the wastewater into steam, removing purities from the steam and then condensing the steam to produce freshwater; 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 and occupies a small area, the quality of produced freshwater is much better than that of conventional wastewater that meets discharge standards, and the resource utilization of chemical wastewater is achieved.

Description

Method and system for hydrogen production and fresh water co-production from chemical wastewater TECHNICAL FIELD

[0001] The present application relates to the technical field of indirect hydrogen production from wastewater, in particular, and especially relates to a method and system for hydrogen production and fresh water co-production from chemical wastewater. BACKGROUND

[0002] The existing chemical wastewater treatment technology route is complex and diversified, and mostly needs to set up wastewater pretreatment, biochemical treatment, advanced treatment and saltwater treatment processes. After high-salinity wastewater is concentrated and crystallized to recover water, the salt is treated as hazardous waste and landfilled. Chemical wastewater is only treated to meet provincial or national discharge standards, and the treated wastewater cannot be reused and is discharged into the municipal sewage pipe 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. Using green electricity generated by renewable energy such as solar energy and wind energy to drive water electrolysis reaction to produce hydrogen gas is of great significance to solve the energy shortage problem and achieve the "double carbon" goal. In the current water electrolysis hydrogen production technology, alkaline water electrolysis has low cost and relatively mature technology, and is the most widely used hydrogen production technology, occupying a dominant position. The "Global Hydrogen Production Water Report" released by the International Renewable Energy Agency (IRENA) shows that the current mainstream hydrogen production methods all need fresh water, mainly concentrated in the processes of hydrogen production and cooling. Each production of 1 kilogram of blue hydrogen needs to consume about 32.2 liters of fresh water. In green hydrogen production, the fresh water consumption of alkaline water electrolysis hydrogen production process for producing 1 kilogram of hydrogen gas is expected to be 22.3 liters. However, the global fresh water resources are extremely limited, and the large-scale popularization and application of water electrolysis hydrogen production technology will undoubtedly exacerbate the problem of fresh water shortage. SUMMARY

[0004] According to the above technical problems, a method and system for hydrogen production and fresh water co-production from chemical wastewater are provided. The present application can realize low-cost wastewater treatment, save the land occupation of wastewater treatment devices, and realize efficient production of hydrogen energy and other products.

[0005] The technical means adopted by the present application are as follows:

[0006] The system for hydrogen production and fresh water production from chemical wastewater comprises a wastewater leading-out unit and an electrolytic water coupling low-temperature distillation integrated system, 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 filtering and circulating unit and a wastewater fresh water production unit, the wastewater leading-out unit is used for supplying organic wastewater or inorganic wastewater to the electrolytic water coupling low-temperature distillation integrated system, the wastewater fresh water production unit is used for heating the wastewater, removing impurities by steam and producing fresh water after condensation; 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 for completing the purification of hydrogen, and the alkali solution filtering and circulating unit is used for completing the forced circulation of alkali solution in the alkaline electrolytic cell unit, the hydrogen separation cooling unit and the oxygen separation cooling unit.

[0007] Further, when the wastewater leading-out unit supplies inorganic wastewater, the inorganic wastewater directly enters the wastewater fresh water production unit.

[0008] Further, when the wastewater leading-out unit supplies organic wastewater, the organic wastewater enters the wastewater fresh water production unit after passing through the oxidation treatment unit.

[0009] Further, the wastewater enters the wastewater fresh water production unit or enters the hydrogen separation cooling unit and the oxygen separation cooling unit.

[0010] Further, the oxidation treatment unit is connected with an oxidant adding unit, and an oxidant is arranged in the oxidation treatment unit, so that the organic wastewater output from the oxidation treatment unit is completely oxidized after the oxidant is added to the oxidation treatment unit.

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

[0012] Further, the gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation cooling unit, and the organic wastewater output from the oxidation treatment unit is completely oxidized.

[0013] Further, the wastewater-to-freshwater 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 connection port, a wastewater inlet, a concentrated brine outlet, a freshwater outlet, and an alkali circulation pipe. The vacuum extraction system connection port is connected to the vacuum extraction system. The wastewater inlet is connected to the wastewater extraction unit or the oxygen separation cooling unit / hydrogen separation cooling unit. The concentrated brine outlet is used to collect concentrated brine. The alkali circulation pipe is used to exchange heat between high-temperature alkali and wastewater, thereby reducing the temperature of the alkali and allowing the wastewater to evaporate into water vapor at the evaporation temperature. The water vapor is condensed by the condenser, and the water receiving plate is used to receive condensed water droplets. The output end of the water receiving plate is connected to the freshwater outlet. The wire mesh separator is arranged in the device cylinder and is used to separate larger droplets and impurities in the water vapor.

[0014] Further, the wastewater-to-freshwater unit is also connected to a freshwater storage unit, which includes but is not limited to a water storage tank and a water storage tank, for storing excess freshwater.

[0015] A method for producing hydrogen and freshwater from chemical wastewater, comprising the following steps:

[0016] S1, confirming the composition of the wastewater, based on whether the wastewater source is organic wastewater or inorganic wastewater, confirming whether to set up an oxidation treatment unit, if it is organic wastewater, then entering step S2, if it is inorganic wastewater, then entering step S3;

[0017] S2, based on the basic information of the wastewater to be treated, confirming the form of the oxidation treatment unit, i.e., using an oxygen internal circulation oxidation treatment method or an external oxidant oxidation treatment method;

[0018] S3, coupling the electrolytic water and low-temperature distillation integrated system with the wastewater extraction unit or the oxidation treatment unit, and starting the production of hydrogen and freshwater from chemical wastewater, wherein,

[0019] The wastewater extraction unit directly or after oxidation by the oxidation treatment unit, transports the wastewater to the wastewater-to-freshwater unit for freshwater production and concentrated brine separation, or after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit, enters the wastewater-to-freshwater unit. The wastewater can assist in cooling in the oxygen separation cooling unit and the hydrogen separation cooling unit.

[0020] The freshwater in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current.

[0021] The oxygen outlet of the alkaline electrolytic cell unit transports oxygen and alkali to the oxygen separation cooling unit for gas-liquid separation. When using the oxygen internal circulation oxidation treatment method, the oxygen is returned to the oxidation treatment unit for reaction.

[0022] The hydrogen outlet of the alkaline electrolytic cell unit transports hydrogen and alkali liquor into the hydrogen separation cooling unit for gas-liquid separation. The hydrogen after preliminary purification and a small amount of water enter the hydrogen purification cooling unit for further purification, and the hydrogen content is ≥ 99.99%. The hydrogen is finally supplied to the user or stored.

[0023] The alkali liquor filtering circulation unit extracts alkali liquor from the oxygen separation cooling unit and the hydrogen separation cooling unit, and after cooling by the waste water to fresh water unit, the alkali liquor is finally transported to the alkaline electrolytic cell unit, completing the cooling and forced circulation of the alkali liquor.

[0024] The heat emitted by the alkali liquor when cooled in the waste water to fresh water unit is used to heat the waste water under negative pressure to produce fresh water. 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.

[0025] Compared with the prior art, the present application has the following advantages: the traditional waste water treatment process has a large area and a complex process. The present application is based on the direct introduction of inorganic waste water into the electrolytic water coupled low-temperature distillation integrated system or the direct introduction of organic waste water after oxidation treatment into the electrolytic water coupled low-temperature distillation integrated system, and the process flow is short and the area is small. The electrolytic water coupled low-temperature distillation integrated system of the present application uses the alkali liquor to be cooled to heat the waste water 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 generated by the waste water to fresh water unit is supplemented to the alkaline electrolytic cell unit as the electrolytic water raw material, which relieves the dependence on fresh water resources, and makes the chemical waste water finally completely change into high-concentration hydrogen, oxygen, fresh water and high-concentration salt. The generated fresh water is much better than the traditional waste water that meets the discharge standard, and realizes the resource utilization of waste water. In addition, the oxygen generated in the system can also be used as the source of oxidation treatment to complete the internal circulation of the system, and the final product is effectively utilized. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0027] Fig. 1 is a whole flow chart of the chemical waste water hydrogen production and fresh water co-production system of the present application.

[0028] Fig. 2 is a schematic diagram of organic waste water treatment of the present application with the addition of an oxidizing agent.

[0029] Fig. 3 is a schematic diagram of organic waste water treatment of the present application with internal circulation. DETAILED DESCRIPTION

[0030] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0031] In order to make the purposes, 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 drawings of the embodiments of the present application. Obviously, the described embodiments are only part 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 creative labor are within the protection scope of the present application.

[0032] It should be noted that the terms used herein are only for describing 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 it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or their combinations.

[0033] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the embodiments are not meant to limit the scope of the present application. It should be apparent that the size of the various parts shown in the drawings is not to scale, and that the drawings are not to be construed as defining limits to the scope of the application. Techniques, methods, and devices known in the art can not be discussed in detail in that they can be fully described in the literature to be readily available to those skilled in the art. In all examples shown and discussed herein, any specific value should be interpreted as merely an example, and not as a limitation. Thus, other examples of the exemplary embodiments can have different values. It should be noted that similar reference numerals and letters in the following drawings represent similar items, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0034] In the description of the application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship is generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, without making the opposite statement, these orientation words do not indicate and imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the application: the orientation words "inner, outer" refer to the inner and outer relative to the contour of each component.

[0035] 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 position relationship of one device or feature with 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 described in the drawings. For example, if the device in the drawing 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.

[0036] In addition, it should be noted that the use of "first", "second" and the like to define parts has only the purpose of facilitating the distinction of the corresponding parts, and the above words have no special meaning unless otherwise stated, therefore, it cannot be understood as a limitation on the scope of protection of the application.

[0037] As shown in Figure 1, the embodiment of the present application discloses a system for hydrogen production and fresh water co-production from chemical wastewater, comprising: a wastewater leading-out unit and an electrolytic water coupled low-temperature distillation integrated system, wherein 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 liquor filtration and circulation unit, and a wastewater fresh water production unit. The wastewater leading-out unit is used to supply organic wastewater or inorganic wastewater to the electrolytic water coupled low-temperature distillation integrated system, mainly comprising a water pump, a check valve, a flow meter and the like (not shown in the figure). The wastewater fresh water production unit is used to heat the wastewater, remove impurities by steam, and produce fresh water after condensation; the output end of the wastewater fresh water production unit is connected with the alkaline electrolytic cell unit, and 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 liquor enter the hydrogen separation and cooling unit, and the oxygen and the alkali liquor enter the oxygen separation and cooling unit; the hydrogen purification and cooling unit is used to complete the purification of hydrogen; and the alkali liquor filtration and circulation unit is used to complete the forced circulation of the alkali liquor in the alkaline electrolytic cell unit, the hydrogen separation and cooling unit, and the oxygen separation and cooling unit. 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 liquor filtration and circulation unit mainly comprises an alkali liquor circulating pump, a check valve, a flow meter and the like.

[0038] In the figure, the baseline is the electrolytic water coupled low-temperature distillation integrated system.

[0039] The hydrogen purification and cooling unit therein carries out deoxygenation on the entering hydrogen, trace oxygen and trace water through a catalytic reaction, removes water and other impurities by using the molecular sieve adsorption principle, and finally purifies the hydrogen to ≥99.99%.

[0040] In the 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; the direct current can be directly connected externally, or the power supply can be completed by converting alternating current into direct current.

[0041] Further, when the wastewater leading-out unit supplies inorganic wastewater, the inorganic wastewater directly enters the wastewater fresh water production unit.

[0042] Further, when the wastewater leading-out unit supplies organic wastewater, the organic wastewater enters the wastewater fresh water production unit after passing through an oxidation treatment unit.

[0043] As an optional embodiment, the oxidation treatment unit adopted by the present application includes advanced oxidation technology, i.e. Fenton oxidation, photocatalytic oxidation, ozone catalytic oxidation, electrochemical oxidation, ultrasonic oxidation, supercritical water oxidation, etc., to oxidize and decompose organic matters into small molecules, until degradation into carbon dioxide CO2 and wastewater containing inorganic salts. In some chemical wastewater, N2 and the like may also be generated, and the CO2 and N2 are exhausted in the present application.

[0044] Further, the wastewater enters the wastewater fresh water production unit or enters the hydrogen separation cooling unit or the oxygen separation cooling unit.

[0045] Further, as shown in FIG. 2, 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 and the like.

[0046] The oxidation treatment unit is provided with an oxidant, so that the organic wastewater output by the oxidation treatment unit is completely oxidized after the oxidant is added to the oxidation treatment unit.

[0047] Further, the hydrogen outlet of the alkaline electrolytic cell unit is connected with the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolytic cell unit is connected with the oxygen separation cooling unit, the alkali inlet of the alkaline electrolytic cell 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 both 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.

[0048] Further, as shown in FIG. 3, the gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation cooling unit, and the oxygen separated by the oxygen separation cooling unit is transported to the oxidation treatment unit, so that the organic wastewater output by the oxidation treatment unit is completely oxidized.

[0049] Further, the wastewater-to-freshwater 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 connection port, a wastewater inlet, a concentrated brine outlet, a freshwater outlet, and an alkali circulation pipe. The vacuum system connection port is connected to the vacuum system. The wastewater inlet is connected to the wastewater leading-out unit, the oxidation treatment unit, the oxygen separation cooling unit, or the hydrogen separation cooling unit. The concentrated brine outlet is used to collect concentrated brine. The alkali circulation pipe is used to exchange heat between high-temperature alkali and wastewater, thereby reducing the temperature of the alkali and allowing the wastewater to evaporate into water vapor at the evaporation temperature. The water vapor is condensed by the condenser. The water receiving plate is used to receive condensed water droplets. The output end of the water receiving plate is connected to the freshwater outlet. The wire mesh separator is arranged in the device cylinder and is used to separate large droplets and impurities in the water vapor.

[0050] Further, the wastewater-to-freshwater unit is further connected to a freshwater storage unit for storing excess freshwater.

[0051] A method for producing hydrogen and freshwater from chemical wastewater, comprising the following steps:

[0052] S1, confirming the composition of the wastewater, based on whether the wastewater source is organic wastewater or inorganic wastewater, confirming whether to set up an oxidation treatment unit, if it is organic wastewater, then entering step S2, if it is inorganic wastewater, then entering step S3;

[0053] S2, based on the basic information of the wastewater to be treated, confirming the form of the oxidation treatment unit, i.e., adopting an oxidation treatment mode of internal oxygen circulation or an oxidation treatment mode of external oxidizing agent;

[0054] S3, coupling an electrolytic water and low-temperature distillation integrated system to the wastewater leading-out unit or the oxidation treatment unit, and starting the production of hydrogen and freshwater from chemical wastewater, wherein,

[0055] The wastewater leading-out unit directly or after oxidation of the wastewater by the oxidation treatment unit, transports the wastewater to the wastewater-to-freshwater unit for the production of freshwater and the separation of concentrated brine, or the wastewater after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit enters the wastewater-to-freshwater unit. The wastewater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit.

[0056] The freshwater in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current.

[0057] The oxygen outlet of the alkaline electrolytic cell unit transports oxygen and alkali 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.

[0058] The hydrogen outlet of the alkaline electrolytic cell unit transports hydrogen and alkali liquor into the hydrogen separation cooling unit for gas-liquid separation, and the hydrogen after preliminary purification and a small amount of water enter the hydrogen purification cooling unit for further purification to a hydrogen content of ≥ 99.99%, and the hydrogen is finally supplied to the user or stored;

[0059] The alkali liquor filtration circulation unit extracts alkali liquor from the oxygen separation cooling unit and the hydrogen separation cooling unit, and after cooling by the waste water to fresh water unit, the alkali liquor is finally transported to the alkaline electrolytic cell unit to complete the cooling and forced circulation of the alkali liquor.

[0060] The heat emitted by the alkali liquor when cooled in the waste water to fresh water unit is used to heat the waste water 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 washing and cooling.

[0061] Embodiment 1

[0062] As shown in FIG. 2, the embodiment of the present application discloses a system for hydrogen co-production of fresh water from completely oxidized organic waste water, which comprises an organic waste water leading-out unit, an oxidation treatment unit, an oxidant adding unit, and an electrolytic water coupled low-temperature distillation integrated system, wherein the electrolytic water coupled low-temperature distillation integrated system comprises an alkaline electrolytic cell, an oxygen separation cooling unit, a hydrogen separation cooling unit, a hydrogen purification cooling unit, an alkali liquor filtration circulation unit, and a waste water to fresh water unit, the oxidation treatment unit is connected with the oxidant adding unit, the organic waste water led out by the organic waste water leading-out unit is treated by the oxidation treatment unit to completely oxidize the organic matter into CO2 and N2, the oxidation treatment unit is connected with the electrolytic water coupled low-temperature distillation integrated system, the waste water to fresh water unit is used to heat the treated waste water, remove impurities by steam, and produce fresh water after condensation; the output end of the waste water to fresh water unit is connected with the alkaline electrolytic cell, 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 and alkali liquor enter the hydrogen separation cooling unit, and the oxygen and alkali liquor enter the oxygen separation cooling unit; the hydrogen purification cooling unit is used to complete the purification of hydrogen, and the alkali liquor filtration circulation unit is used to complete the forced circulation of alkali liquor in the alkaline electrolytic cell, the hydrogen separation cooling unit, and the oxygen separation cooling unit. The additional fresh water co-produced by the waste water to fresh water unit is output through a fresh water recovery port.

[0063] In the figure, the inner baseline is the electrolytic water coupled low-temperature distillation integrated system.

[0064] The hydrogen purification module therein deoxidizes the entered hydrogen, trace oxygen, and trace water through catalytic reaction, removes water and other impurities by using the molecular sieve adsorption principle, and finally purifies the hydrogen to ≥ 99.99%.

[0065] In this embodiment, fresh water in the alkaline electrolytic cell is decomposed into hydrogen and 1 / 2 oxygen under the action of direct current. The direct current can be directly connected or supplied by converting alternating current into direct current.

[0066] As an optional embodiment, the oxidation treatment unit of the present application includes advanced oxidation technology, i.e. Fenton oxidation, photocatalytic oxidation, ozone catalytic oxidation, electrochemical oxidation, ultrasonic oxidation, supercritical water oxidation, etc. to oxidize and decompose organic matters into small molecules, until degradation into carbon dioxide CO2 and wastewater containing inorganic salts. In some organic wastewater, N2 may also be generated. In the present application, CO2 and N2 are exhausted.

[0067] Further, the treated wastewater enters the wastewater-to-fresh water unit. Alternatively, the wastewater enters the wastewater-to-fresh water unit or enters the hydrogen separation cooling unit or the oxygen separation cooling unit. This arrangement can also recover the heat of the hydrogen separation cooling unit and the oxygen separation cooling unit using the treated wastewater, thereby improving the energy utilization rate.

[0068] Further, the hydrogen outlet of the alkaline electrolytic cell is connected to the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolytic cell is connected to the oxygen separation cooling unit, the alkali inlet of the alkaline electrolytic cell is connected to the wastewater-to-fresh water 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 to 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 both connected to the alkali filtration and circulation unit to provide high-temperature alkali to be cooled, and the fresh water outlet of the wastewater-to-fresh water unit is connected to the hydrogen separation cooling unit.

[0069] Further, the wastewater-to-fresh water unit includes 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 connection port, a wastewater inlet, a concentrated brine outlet, a fresh water outlet, and an alkali circulation pipe. The vacuum pumping system connection port is connected to the vacuum pumping system, and the wastewater inlet is connected to the wastewater leading-out unit or the oxygen separation cooling unit / hydrogen separation cooling unit. The concentrated brine outlet is used to collect concentrated brine, and the alkali circulation pipe is used to exchange heat between high-temperature alkali and wastewater, thereby reducing the temperature of the alkali and allowing the wastewater to evaporate into water vapor at the evaporation temperature. The water vapor is condensed by the condenser, and the water receiving plate is used to receive condensed water droplets. The output end of the water receiving plate is connected to the fresh water outlet. The wire mesh separator is arranged in the device cylinder and is used to separate larger droplets and impurities in the water vapor.

[0070] In this embodiment, the oxidizing agent stored in the oxidizing agent adding unit includes chlorine and oxygen, the chlorine includes gaseous chlorine, liquid chlorine, sodium hypochlorite, calcium hypochlorite and chlorine dioxide, and the oxygen includes oxygen in air, ozone, hydrogen peroxide and potassium permanganate. According to the actual application scene, the gaseous, solid and liquid raw materials are added into the oxidation treatment unit by direct adding or dissolving the gaseous and solid raw materials into solution and then pumping into the oxidation treatment unit. In some other advanced oxidation treatment processes, the corresponding equipment is used to add the oxidizing agent.

[0071] Further, the wastewater to fresh water unit is also connected with a fresh water storage unit, such as a water storage tank, for storing excess fresh water.

[0072] A method for completely oxidizing organic wastewater to produce hydrogen and co-produce fresh water, comprising the following steps:

[0073] The oxidizing agent adding unit is set based on the preset oxidizing agent;

[0074] The wastewater leading-out unit, the oxidation treatment unit and the electrolytic water coupled low-temperature distillation integrated system are connected, and the oxidizing agent adding unit and the oxidation treatment unit are connected,

[0075] The organic wastewater leading-out unit transports the organic wastewater to the oxidation treatment unit, and the organic matter in the organic wastewater is completely oxidized into CO2 and N2 in the oxidation treatment unit, and the CO2 and N2 are exhausted through the exhaust pipe;

[0076] The treated wastewater is directly transported to the wastewater to fresh water unit for fresh water production and concentrated brine separation, or is transported to the wastewater to fresh water unit after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit, and the treated wastewater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit;

[0077] The fresh water in the alkaline electrolytic cell is decomposed into hydrogen and oxygen under the action of direct current;

[0078] The oxygen outlet of the alkaline electrolytic cell transports oxygen and alkali liquor to the oxygen separation cooling unit for gas-liquid separation;

[0079] The hydrogen outlet of the alkaline electrolytic cell transports hydrogen and alkali liquor to the hydrogen separation cooling unit for gas-liquid separation, the hydrogen and a small amount of water after preliminary purification are further purified in the hydrogen purification cooling unit to a hydrogen content of ≥99.99%, and the hydrogen is finally supplied to the user or stored;

[0080] The alkali liquor filtering and circulating unit extracts the alkali liquor in the oxygen separation cooling unit and the hydrogen separation cooling unit, and after cooling by the wastewater to fresh water unit, the alkali liquor is finally transported to the alkaline electrolytic cell to complete the cooling and forced circulation of the alkali liquor;

[0081] The heat emitted by the lye when cooling the wastewater-to-freshwater unit is used to heat the wastewater under negative pressure to produce fresh water, which is transported to the hydrogen separation module to supplement the raw fresh water used for electrolysis and also to assist in hydrogen washing and cooling.

[0082] Embodiment 2

[0083] As shown in FIG. 3, the embodiment of the present application discloses a self-oxygen-supplying organic wastewater-to-hydrogen cogeneration fresh water system, which comprises an organic wastewater leading-out unit, an oxidation treatment unit, and an electrolytic water coupled low-temperature distillation integrated system. The electrolytic water coupled low-temperature distillation integrated system comprises an alkaline electrolytic cell, an oxygen separation cooling unit, a hydrogen separation cooling unit, a hydrogen purification cooling unit, a lye filtration and circulation unit, and a wastewater-to-freshwater unit. The organic wastewater led out by the organic wastewater leading-out unit is treated by the oxidation treatment unit to completely oxidize the organic matter into CO2 and N2. The oxidation treatment unit is connected to the electrolytic water coupled low-temperature distillation integrated system. The wastewater-to-freshwater unit is used to heat the treated wastewater, remove impurities by steam, and produce fresh water after condensation. The output end of the wastewater-to-freshwater unit is connected to 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 cooling unit, and the oxygen and the lye enter the oxygen separation cooling unit. The hydrogen purification cooling unit is used to complete the purification of hydrogen. The lye filtration and circulation unit is used to complete the forced circulation of the lye in the alkaline electrolytic cell and the hydrogen separation cooling unit and the oxygen separation cooling unit. The output end of the oxygen separation cooling unit is connected to the oxidation treatment unit through a pipeline. The additional fresh water cogenerated by the wastewater-to-freshwater unit is output through a fresh water recovery port.

[0084] In the figure, the baseline is the electrolytic water coupled low-temperature distillation integrated system.

[0085] The hydrogen purification module therein deoxidizes the entering hydrogen, trace oxygen, and trace water through catalytic reaction, removes water and other impurities by using the molecular sieve adsorption principle, and finally purifies the hydrogen to ≥99.99%.

[0086] In this 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. The direct current can be directly connected externally, or the power supply can be completed by converting alternating current into direct current.

[0087] As an optional implementation, the oxidation treatment unit used in the present application comprises advanced oxidation technologies, i.e., Fenton oxidation, photocatalytic oxidation, ozone catalytic oxidation, electrochemical oxidation, ultrasonic oxidation, supercritical water oxidation, etc., to oxidize and decompose the organic matter into small molecules, until degradation into carbon dioxide CO2 and wastewater containing inorganic salts. In some organic wastewater, N2 and the like may also be generated, and the CO2 and N2 in the present application are exhausted.

[0088] Further, the treated organic wastewater is introduced into the wastewater desalination unit, or into the hydrogen separation cooling unit or the oxygen separation cooling unit as cooling water. This arrangement can also recover the heat of the hydrogen separation cooling unit and the oxygen separation cooling unit using the treated wastewater, thereby improving the energy utilization rate.

[0089] Further, the hydrogen outlet of the alkaline electrolyzer is connected to the hydrogen separation cooling unit, the oxygen outlet of the alkaline electrolyzer is connected to the oxygen separation cooling unit, the alkali inlet of the alkaline electrolyzer is connected to the wastewater desalination 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 to 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 to the alkali filtration and circulation unit to provide high-temperature alkali to be cooled, and the fresh water outlet of the wastewater desalination unit is connected to the hydrogen separation cooling unit.

[0090] Further, the wastewater desalination unit comprises a device cylinder, a vacuum system, a condenser, a water receiving plate, and a wire mesh separator. The device cylinder is provided with a vacuum system connection port, a wastewater inlet, a concentrated brine outlet, a fresh water outlet, and an alkali circulation pipe. The vacuum system connection port is connected to the vacuum system, and the wastewater inlet is connected to the wastewater leading-out unit or the oxygen separation cooling unit / hydrogen separation cooling unit. The concentrated brine outlet is used to collect concentrated brine, and the alkali circulation pipe is used to exchange heat between high-temperature alkali and wastewater, thereby reducing the temperature of the alkali and allowing the wastewater to evaporate into water vapor at the evaporation temperature. The water vapor is condensed by the condenser, and the water receiving plate is used to receive condensed water droplets. The output end of the water receiving plate is connected to the fresh water outlet, and the wire mesh separator is arranged in the device cylinder to separate larger droplets and impurities in the water vapor.

[0091] Further, the wastewater desalination unit is also connected to a fresh water storage unit, such as a water tank, for storing excess fresh water.

[0092] A method for producing hydrogen and fresh water from organic wastewater with self-supplied oxygen, comprising the following steps:

[0093] The wastewater leading-out unit, the oxidation treatment unit, and the electrolytic water coupled low-temperature distillation integrated system are connected, wherein the oxygen separation cooling unit of the electrolytic water coupled low-temperature distillation integrated system is connected to the oxidation treatment unit,

[0094] The organic wastewater leading-out unit delivers organic wastewater to the oxidation treatment unit, and the organic matter in the organic wastewater is completely oxidized into CO2 and N2 in the oxidation treatment unit. The CO2 and N2 are discharged through a discharge pipe.

[0095] The wastewater after the oxidation treatment is directly delivered to the wastewater fresh water production unit to produce fresh water and separate concentrated brine, or is delivered to the wastewater fresh water production unit after passing through the oxygen separation cooling unit and the hydrogen separation cooling unit, and the wastewater can play an auxiliary cooling role in the oxygen separation cooling unit and the hydrogen separation cooling unit;

[0096] The fresh water in the alkaline electrolytic cell is decomposed into hydrogen and oxygen under the action of direct current;

[0097] The oxygen outlet of the alkaline electrolytic cell delivers oxygen and alkali liquor to the oxygen separation cooling unit to perform 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;

[0098] The hydrogen outlet of the alkaline electrolytic cell delivers hydrogen and alkali liquor to the hydrogen separation cooling unit to perform gas-liquid separation, and the hydrogen after preliminary purification and a small amount of water enter the hydrogen purification cooling unit to be further purified to a hydrogen content of ≥99.99%, and the hydrogen is finally supplied to a user or stored;

[0099] The alkali liquor filtration circulation unit extracts alkali liquor from the oxygen separation cooling unit and the hydrogen separation cooling unit, and after cooling by the wastewater fresh water production unit, the alkali liquor is finally delivered to the alkaline electrolytic cell to complete the cooling and forced circulation of the alkali liquor;

[0100] 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 delivered 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.

[0101] 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 for 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 and fresh water co-production from chemical wastewater, characterized in that, The application relates to a wastewater leading-out unit and an electrolytic water coupled low-temperature distillation integrated system, wherein the electrolytic water coupled 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 liquor filtering circulation unit and a wastewater fresh water production unit; the wastewater leading-out unit is used for supplying organic wastewater or inorganic wastewater to the electrolytic water coupled low-temperature distillation integrated system. The wastewater fresh water production unit is used for heating wastewater, removing impurities through steam and producing fresh water after condensation; the output end of the wastewater fresh water production unit is connected with the alkaline electrolytic cell unit; fresh water in the alkaline electrolytic cell unit is decomposed into hydrogen and oxygen under the action of direct current; hydrogen and alkali liquor enter the hydrogen separation cooling unit; oxygen and alkali liquor enter the oxygen separation cooling unit; the hydrogen purification cooling unit is used for completing hydrogen purification; the alkali liquor filtering circulation unit is used for completing forced circulation of alkali liquor in the alkaline electrolytic cell unit and the hydrogen separation cooling unit and the oxygen separation cooling unit. When the wastewater leading-out unit supplies inorganic wastewater, the inorganic wastewater directly enters the wastewater fresh water production unit.

2. The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, When the wastewater leading-out unit supplies organic wastewater, the organic wastewater enters the wastewater fresh water production unit after passing through an oxidation treatment unit. 3.The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, Wastewater enters the wastewater fresh water production unit or enters the hydrogen separation cooling unit and the oxygen separation cooling unit.

4. The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, The oxidation treatment unit is connected with an oxidant adding unit, and an oxidant is arranged in the oxidation treatment unit, so that the organic wastewater output from the oxidation treatment unit is completely oxidized after the oxidant is added into the oxidation treatment unit.

5. The system for hydrogen co-production with fresh water from chemical wastewater according to claim 3, characterized in that, The hydrogen outlet of the alkaline electrolytic cell unit is connected with the hydrogen separation cooling unit; the oxygen outlet of the alkaline electrolytic cell unit is connected with the oxygen separation cooling unit; the alkali liquor inlet of the alkaline electrolytic cell unit is connected with the wastewater fresh water production unit; the oxygen separation cooling unit separates oxygen and alkali liquor through a gas-liquid separation method; the hydrogen separation cooling unit separates hydrogen and alkali liquor through a gas-liquid separation method; the hydrogen outlet of the hydrogen separation cooling unit is connected with the hydrogen purification cooling unit; the alkali liquor outlet of the oxygen separation cooling unit and the alkali liquor outlet of the hydrogen separation cooling unit are connected with the alkali liquor filtering circulation unit, so as to provide high-temperature alkali liquor to be cooled; and the fresh water outlet of the wastewater fresh water production unit is connected with the hydrogen separation cooling unit. 6.The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, The gas inlet end of the oxidation treatment unit is connected with the output end of the oxygen separation cooling unit, and the organic wastewater output from the oxidation treatment unit is completely oxidized.

7. The system for hydrogen co-production with fresh water from chemical wastewater according to claim 3, characterized in that, ​ 8.The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, 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 concentrated brine outlet, a fresh water outlet and an alkali liquid circulation pipe. The vacuum extraction system connecting port is connected with the vacuum extraction system. The wastewater inlet is connected with a wastewater extraction unit or an oxygen separation cooling unit / hydrogen separation cooling unit. The concentrated brine outlet is used for collecting concentrated brine. The alkali liquid circulation pipe is used for heat exchange between high-temperature alkali liquid and wastewater, so as to reduce the temperature of the alkali liquid 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 droplets and impurities in the water vapor. 9.The system for hydrogen co-production with fresh water from chemical wastewater according to claim 1, characterized in that, The wastewater fresh water production unit is further connected with a fresh water storage unit for storing excess fresh water.

10. The method for co-producing hydrogen and fresh water from chemical wastewater according to any one of claims 1 to 9, characterized in that, The method comprises the following steps: S1, confirming the composition of the 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; 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 addition of an oxidant; S3, connecting the electrolytic water coupling low-temperature distillation integrated system with the wastewater extraction unit or the oxidation treatment unit, and starting the production of hydrogen and fresh water from chemical wastewater, wherein, The wastewater extraction unit directly or after oxidation of the wastewater extraction unit, transports the wastewater to the wastewater fresh water production unit for the production of fresh water and the separation of concentrated brine, or after the oxygen separation cooling unit and the hydrogen separation cooling unit, enters the wastewater fresh water production unit. The wastewater can assist in cooling in the oxygen separation cooling unit and the hydrogen separation cooling unit; The fresh water in the alkali electrolytic tank unit is decomposed into hydrogen and oxygen under the action of direct current; The oxygen outlet of the alkali electrolytic tank unit transports oxygen and alkali liquid to the oxygen separation cooling unit for gas-liquid separation. When the oxidation treatment mode of oxygen internal circulation is adopted, the oxygen is returned to the oxidation treatment unit for reaction. The hydrogen outlet of the alkali electrolytic tank unit transports hydrogen and alkali liquid 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 ≥99.99%. The hydrogen is finally supplied to the user or stored. The alkali liquid filtration circulation unit extracts the alkali liquid in the oxygen separation cooling unit and the hydrogen separation cooling unit, and after cooling by the wastewater fresh water production unit, finally transports the alkali liquid to the alkali electrolytic tank unit, so as to complete the cooling and forced circulation of the alkali liquid. The heat emitted by the alkali liquid during cooling in 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 transported to the hydrogen separation module and is used to supplement the raw material fresh water for electrolysis, and also assists in realizing hydrogen washing and cooling.

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