Electrochemical ammonia-nitrogen recovery device and method for high-salt ammonia-nitrogen waste liquid of thermal power plant

Abstract

The application relates to an electrochemical ammonia nitrogen recovery device and method for high-salt ammonia nitrogen waste liquid of a thermal power plant, which comprises a treatment bin, a cathode part, an anode part, a separation film group and a power supply part; the separation film group comprises a first film part, the first film part is arranged in the treatment bin and separates the treatment bin into a recovery chamber and a waste liquid chamber, the anode part is arranged in the recovery chamber, and the cathode part is arranged in the waste liquid chamber; the power supply part is electrically connected with the cathode part and the anode part; the cathode part is arranged in the waste liquid chamber, the anode part is arranged in the recovery chamber, alkali is generated by electrolysis of the cathode part by the power supply part, and acid is generated by electrolysis of the anode part; then, ammonia nitrogen contained in waste liquid in the waste liquid chamber reacts with the alkali to form free ammonia, enters the recovery chamber through the first film part, is concentrated under the action of the acid in the recovery chamber, ammonia contained in the waste liquid is reduced into ammonia by the alkali, and finally is concentrated by the acid in the recovery chamber; the ammonia nitrogen in the waste liquid is recovered without adding chemical agents, recovery steps are simplified, and cost input is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-salt ammonia-nitrogen waste liquid treatment, in particular to an electrochemical ammonia-nitrogen recovery device and method for high-salt ammonia-nitrogen waste liquid in a thermal power plant. BACKGROUND

[0002] With the increase of condensate polishing facilities in thermal power plants, liquid ammonia as a pH regulator for feed water and condensate water inevitably produces high-ammonia-nitrogen waste liquid. Such waste liquid generally has a very high ammonia-nitrogen concentration and an imbalanced ratio of nutrients, making it difficult to be biologically treated. In addition, it has the characteristics of small water volume, high salinity, and low suspended solids content. If such waste liquid is directly discharged without treatment, it will cause eutrophication, black and odorous water, and other phenomena. The treatment of such high-concentration ammonia-nitrogen waste liquid is the key to the ammonia-nitrogen discharge standard of the power plant.

[0003] In the prior art, the polishing regeneration waste liquid and other high-salt ammonia-nitrogen waste liquid in the power plant are usually collected into the waste liquid treatment system of the power plant and treated together with chemical waste liquid and unit waste liquid. However, the system can only dilute ammonia-nitrogen and cannot effectively treat and recover ammonia-nitrogen. If ammonia-nitrogen treatment and recovery is to be achieved, additional chemical agents are required, and the operation steps are relatively complex and cumbersome. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defect that the ammonia-nitrogen recovery and treatment in the prior art for the thermal power plant can only be combined with chemical agents, thereby providing an electrochemical ammonia-nitrogen recovery device and method for high-salt ammonia-nitrogen waste liquid in a thermal power plant.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] An electrochemical ammonia-nitrogen recovery device for high-salt ammonia-nitrogen waste liquid in a thermal power plant, comprising a treatment bin, a cathode piece, an anode piece, a separation membrane group, and a power supply piece.

[0007] The separation membrane group comprises a first membrane piece, which is arranged in the treatment bin and separates the treatment bin into a recovery chamber and a waste liquid chamber. The waste liquid chamber contains ammonia-nitrogen waste liquid, and the recovery chamber contains an ammonium salt solution.

[0008] The anode piece is arranged in the recovery chamber, the cathode piece is arranged in the waste liquid chamber, and the first membrane piece is used to recover free ammonia generated in the waste liquid chamber.

[0009] The power supply piece is electrically connected to the cathode piece and the anode piece, respectively.

[0010] Preferably, the separation membrane group further comprises a second membrane piece and a third membrane piece.

[0011] The processing bin further comprises a brine chamber, the recovery chamber is separated from the brine chamber by the second membrane element, and the waste liquid chamber is separated from the brine chamber by the third membrane element.

[0012] Preferably, the waste liquid chamber has a waste liquid inlet and a waste liquid outlet, and the waste liquid inlet is higher than the waste liquid outlet in the vertical direction.

[0013] The waste liquid inlet and the waste liquid outlet are respectively provided with a waste liquid cover, and the waste liquid cover is detachably connected with the waste liquid inlet and the waste liquid outlet.

[0014] Preferably, the recovery chamber has at least two recovery ports for circulating recovered ammonia nitrogen.

[0015] The recovery ports are respectively provided with a recovery cover, and the recovery cover is detachably connected with the recovery port.

[0016] Preferably, the power supply element has a power-on voltage greater than 2.8V.

[0017] Preferably, the anode element and the cathode element both comprise a metal material.

[0018] Preferably, the first membrane element comprises a hydrophobic and air-permeable plastic material.

[0019] Preferably, the pore size of the first membrane element is 0.22-1μm.

[0020] An electrochemical ammonia nitrogen recovery method for high-salt ammonia nitrogen waste liquid in a thermal power plant, which is performed by using the recovery device according to any one of the above, and comprises the following steps:

[0021] An ammonium salt solution is added to the recovery chamber in advance, waste liquid containing ammonia nitrogen is added to the waste liquid chamber, the power supply element is used to supply power to the anode element and the cathode element respectively, the cathode element electrolysis generates alkali, and the anode element electrolysis generates acid; the ammonia nitrogen contained in the waste liquid in the waste liquid chamber is converted into free ammonia when meeting alkali, and the free ammonia enters the recovery chamber through the first membrane element and is absorbed and concentrated by the acid in the recovery chamber.

[0022] The nitrogen contained in the waste liquid is reduced to ammonia when meeting alkali, and is finally absorbed and concentrated by the acid in the recovery chamber.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The technical scheme provided by the above technical scheme is an electrochemical ammonia nitrogen recovery device and method for high-salt ammonia nitrogen waste liquid of a thermal power plant, a cathode part is arranged in a waste liquid chamber with ammonia nitrogen waste liquid, an anode part is arranged in a recovery chamber with an acid or pure ammonium salt solution, a power supply part is used to supply power to the cathode part and the anode part, so that the cathode part electrolyzes to generate alkali and the anode part electrolyzes to generate acid; then, ammonia nitrogen contained in the waste liquid in the waste liquid chamber reacts with the alkali to form free ammonia and enters the recovery chamber through the first membrane part, and the ammonia is concentrated under the action of the acid in the recovery chamber; and nitrogen contained in the waste liquid is reduced to ammonia under the action of the alkali, and is finally absorbed and concentrated by the acid in the recovery chamber; the electrochemical method is used to recover the ammonia nitrogen in the waste liquid without adding any chemical agent, which on the one hand simplifies the recovery steps, saves the cost investment, makes the recovery scheme more economical, and on the other hand realizes resource recycling and reuse, and avoids resource waste; meanwhile, under the action of the first membrane part, the purity and quality of the recovered ammonia nitrogen are ensured, and the acid and alkali generated by electrolysis can react with the ammonia nitrogen and free ammonia in the waste liquid in time, and the ammonia nitrogen recovery efficiency is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme in the specific embodiments or prior art of the present application, the drawings needed to be used in the specific embodiments or prior art description will be briefly introduced as follows. 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.

[0026] Figure 1 The overall structure of the recovery device provided in an embodiment of the present application is shown in the figure.

[0027] Figure 2 For Figure 1 The front view is shown.

[0028] Figure 3 For Figure 1 The top view is shown.

[0029] Figure 4 For Figure 1 The side view is shown.

[0030] Explanation of reference signs:

[0031] 1, treatment bin; 11, first membrane part; 12, recovery chamber; 121, anode part; 122, second membrane part; 123, recovery port; 13, waste liquid chamber; 131, cathode part; 132, third membrane part; 133, waste liquid inlet; 134, waste liquid outlet; 14, salt water chamber;

[0032] 2, power supply; 21, wire harness. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] This invention provides an electrochemical ammonia nitrogen recovery device for high-salt ammonia nitrogen waste liquid from thermal power plants, such as... Figures 1 to 4 The device shown includes: a processing chamber 1, a cathode 131, an anode 121, a separator membrane assembly, and a power supply unit. The processing chamber 1 comprises a conventional chamber capable of holding a medium. The cathode 131 and anode 121 are reaction components in electrochemistry. The separator membrane assembly includes a first membrane 11, which is a commercially available hydrophobic and breathable membrane that can selectively permeate gas molecules from an aqueous solution and is hydrophobic. The power supply unit is used in conjunction with the cathode 131 and anode 121 to perform electrochemical reactions. The power supply for the reaction is as follows: Specifically, the first membrane element 11 is installed in the processing chamber 1, which is divided into a recovery chamber 12 and a waste liquid chamber 13. The waste liquid chamber 13 contains waste liquid with ammonia nitrogen generated by the thermal power plant, and the recovery chamber 12 contains an ammonium salt solution. The recovery chamber 12 is used to absorb and concentrate the ammonia nitrogen recovered from the waste liquid. Correspondingly, the anode element 121 is installed in the recovery chamber 12, and the cathode element 131 is installed in the waste liquid chamber 13. The power supply is connected to the cathode element 131 and the anode element 121 respectively.

[0037] That is, the ammonium salt solution is added to the recovery chamber 12, and the waste liquid is added to the waste liquid chamber 13; meanwhile, the power supply is used to electrify the anode 121 in the recovery chamber 12 and the cathode 131 in the waste liquid chamber 13, so that the anode 121 generates acid during electrolysis, and the cathode 131 generates alkali during electrolysis; then the waste liquid in the waste liquid chamber 13 converts ammonia nitrogen into free ammonia under the action of alkali, and the converted free ammonia enters the recovery chamber 12 after being purified by the first membrane 11 and is absorbed and concentrated under the action of acid; and the nitrogen in the waste liquid is reduced to ammonia by the alkali, and finally enters the recovery chamber 12 with the free ammonia through the first membrane 11 and is absorbed and concentrated by the acid.

[0038] Preferably, the cathode 131 is an electronic pole that can undergo a reduction reaction in electrochemistry, and the material of the cathode 131 includes stainless steel mesh, foamed nickel, titanium mesh, etc.; the anode 121 is an electronic pole that can make the electrolyte undergo an oxidation reaction in electrochemistry, and the material of the anode 121 includes platinum series metals and their compounds, ruthenium and ruthenium oxide, nickel, cobalt, manganese compounds, etc.; and the cathode 131 and the anode 121 are both columnar electronic poles in this embodiment, but in actual application, the shape and structure of the cathode 131 and the anode 121 are not limited to columnar, and can be determined according to actual needs; and the first membrane 11 includes a hydrophobic and air-permeable membrane with a material of PTFE (polytetrafluoroethylene), PVDF (polyvinylidene fluoride), PP (polypropylene), etc., and the pore size of the first membrane 11 selected according to actual recovery needs is 0.22-1 μm, so as to ensure that the medium in a molecular state, such as free ammonia, can pass normally; wherein the recovery chamber 12 can be acid or pure ammonium salt solution, and the waste liquid in the waste liquid chamber 13 is high ammonia nitrogen waste liquid generated by a thermal power plant.

[0039] The cathode 131 is arranged in the waste liquid chamber 13 with ammonia nitrogen waste liquid, and the anode 121 is arranged in the recovery chamber 12 with ammonium salt solution; the power supply is used to supply power to the cathode 131 and the anode 121, so that the anode 121 generates alkali during electrolysis, and the anode 121 generates acid during electrolysis; then the ammonia nitrogen contained in the waste liquid in the waste liquid chamber 13 forms free ammonia in the presence of alkali and enters the recovery chamber 12 through the first membrane 11, and is absorbed and concentrated in the recovery chamber 12 under the action of acid; and the nitrogen contained in the waste liquid is reduced to ammonia by the alkali, and is finally absorbed and concentrated by the acid in the recovery chamber; the electrochemical method is used to realize the recovery of ammonia nitrogen in the waste liquid without adding any chemical agent, which on the one hand simplifies the recovery steps, saves the cost investment, makes the recovery scheme more economical, and on the other hand realizes the resource recycling and reuse, and avoids resource waste; meanwhile, under the action of the first membrane 11, the purity and quality of the recovered ammonia nitrogen are ensured, and the acid and alkali generated by electrolysis can react with ammonia nitrogen and free ammonia in the waste liquid, which further improves the recovery efficiency of ammonia nitrogen.

[0040] Specifically, as shown in FIG. 1, the ammonia nitrogen recovery device 1 includes a recovery chamber 12, a waste liquid chamber 13, a first membrane 11, a power supply, a cathode 131 and an anode 121.Figure 1 As shown, the separation membrane group further comprises a second membrane piece 122 and a third membrane piece 132; wherein the second membrane piece 122 is a kind of high polymer polymer membrane containing basic active groups, which has selective permeability to anions, and is also called selective permeability membrane, namely anion exchange membrane; the anode piece 121 comprises the anode piece 121 and the third membrane piece 132, and the third membrane piece 132 is a kind of membrane with selective effect on cations, which repels anions, and is usually sulfonic acid type, with fixed groups and dissociable ions, namely cation exchange membrane.

[0041] Further, in order to ensure that the ammonia nitrogen in the waste liquid is recovered more completely, the treatment bin 1 further comprises a brine chamber 14, which is used for adding electrolyte to ensure the conductivity of the whole device and the purity of the recovered substances, and the electrolyte in the brine chamber 14 is brine; specifically, the recovery chamber 12 is separated from the brine chamber 14 by the second membrane piece 122, the waste liquid chamber 13 is separated from the brine chamber 14 by the third membrane piece 132, the cathode piece 131 is arranged in the waste liquid chamber 13, and the anode piece 121 is arranged in the recovery chamber 12; then the cations in the waste liquid chamber 13 enter the brine chamber 14 through the third membrane piece 132, ensuring the conductivity of the whole device; and the sulfate ions (anions) in the brine chamber 14 can enter the recovery chamber 12 through the second membrane piece 122 and combine with the ammonium ions in the recovery chamber 12 to form ammonium sulfate, while the remaining impurities and cations are blocked by the second membrane piece 122, thereby ensuring the purity of the recovered product in the recovery chamber 12.

[0042] Preferably, the waste liquid chamber 13 is provided with a waste liquid inlet 133 and a waste liquid outlet 134, and the waste liquid inlet 133 is used for waste liquid filling, and the waste liquid outlet 134 is used for waste liquid circulation after treatment; specifically, a waste liquid cover is arranged on the waste liquid inlet 133 and the waste liquid outlet 134, and the waste liquid cover is detachably connected with the waste liquid inlet 133 and the waste liquid outlet 134; through the connection relationship between the waste liquid cover and the waste liquid inlet 133 and the waste liquid outlet 134, the waste liquid generated by the thermal power plant can be treated in a batch mode; that is, a certain amount of waste liquid is added to the waste liquid chamber 13 through the waste liquid inlet 133, and before this, the waste liquid cover has been arranged on the waste liquid outlet 134; after the filling is completed, the waste liquid cover is arranged on the waste liquid inlet 133 for recycling; after the treatment of the certain amount of waste liquid in the waste liquid chamber 13 is completed, the waste liquid cover on the waste liquid outlet 134 is removed, so that the waste liquid in the waste liquid chamber 13 can be discharged; it is worth noting that in order to facilitate the filling and drainage of the waste liquid in the waste liquid chamber 13, the height of the waste liquid inlet 133 in the vertical direction is different from that of the waste liquid outlet 134, and the height of the waste liquid inlet 133 in the vertical direction is higher than that of the waste liquid outlet 134, forming a "high-in and low-out" structure, thereby reducing the resistance of the waste liquid filling and drainage.

[0043] In some cases, the device is also equipped with a pump body; specifically, the pump body is connected between the waste liquid chamber 13 and the waste liquid source of the thermal power plant, and the waste liquid is transported to the waste liquid chamber 13 through the pump body, so as to realize continuous treatment of the waste liquid; that is, the pump body is started, and the waste liquid generated by the thermal power plant continuously enters the waste liquid chamber 13 for treatment under the action of the pump body through the waste liquid inlet 133, and the treated waste liquid is continuously discharged from the waste liquid outlet 134; further improve the efficiency of waste liquid treatment.

[0044] Specifically, at least two recovery ports 123 are provided on the recovery chamber 12, and the two recovery ports 123 are used for circulating the recovered ammonia nitrogen; and in order to facilitate absorption and concentration, the recovery chamber 12 further comprises a recovery cover, and the recovery cover is provided in one-to-one correspondence with the number of recovery ports 123, and the recovery cover and the recovery port 123 are detachably connected; that is, when the recovery chamber 12 recovers ammonia nitrogen, the recovery cover is sealed on the recovery port 123 to continuously concentrate the recovered ammonia nitrogen. Based on the fact that the recovered ammonia nitrogen is in a gaseous state, a sealing ring is usually provided on the recovery cover to improve the sealing performance of the connection and to prevent the recovered ammonia nitrogen in the recovery chamber 12 from leaking; and when the capacity of the recovery chamber 12 is insufficient or the ammonia nitrogen in the recovery chamber 12 needs to be transferred, other storage cavities can be connected to the recovery port 123.

[0045] As shown in Figure 1 The power supply includes a power supply 2 and a plurality of wire harnesses 21, and the power supply 2 is connected to the cathode member 131 and the anode member 121 through the wire harnesses 21; and in order to ensure the electrolysis effect, the voltage of the power supply 2 needs to be greater than 2.8V; in addition, when the voltage of the power supply 2 does not meet the electrolysis requirement, a voltage transformation device is additionally provided in the connection circuit; the specific arrangement is determined according to actual needs.

[0046] An electrochemical ammonia nitrogen recovery method for high-salt ammonia nitrogen waste liquid of a thermal power plant is performed by using the above-mentioned recovery device, mainly including the following steps: adding acid or pure ammonium salt solution into the recovery chamber 12 in advance, adding waste liquid into the waste liquid chamber 13, that is, the waste liquid is the waste liquid with ammonia nitrogen generated by the thermal power plant; connecting the power supply 2 to the cathode member 131 and the anode member 121 through the wire harnesses 21, and supplying power to the cathode member 131 and the anode member 121 by using the power supply 2 to perform electrolysis; then in the waste liquid chamber 13, the cathode member 131 generates alkali during electrolysis, so that the waste liquid containing ammonia nitrogen in the waste liquid chamber 13 is converted into free ammonia by the alkali; in the recovery chamber 12, the anode member 121 generates acid during electrolysis, further, the free ammonia in the waste liquid chamber 13 is filtered and purified by the first membrane member 11 and then enters the recovery chamber 12, and the free ammonia entering the recovery chamber 12 is absorbed and concentrated by the acid; still further, the nitrogen in the waste liquid chamber 13 is reduced to ammonia by the alkali, and finally the ammonia and the free ammonia pass through the first membrane member 11 and enter the recovery chamber 12 to be absorbed and concentrated.

[0047] Further, the electrolyte is added in the salt water chamber 14, and the electrolyte in the salt water chamber 14 is salt water; the remaining cations in the waste liquid chamber 13 can enter the salt water chamber 14 through the third membrane 132, thereby ensuring the overall electrical conductivity of the device; and the remaining impurities and anions in the waste liquid chamber 13 are blocked by the third membrane 132, thereby ensuring the purity of the ammonia nitrogen recovered in the recovery chamber 12; further, the sulfate ions (anions) in the salt water chamber 14 can enter the recovery chamber 12 through the second membrane 122 and combine with the ammonium ions in the recovery chamber 12 to form ammonium sulfate, and the remaining impurities and cations are blocked by the second membrane 122, thereby ensuring the purity of the ammonia nitrogen recovered in the recovery chamber 12.

[0048] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application, and any non-essential changes and substitutions made by those skilled in the art on the basis of the present application shall fall within the scope of protection of the present application.

Claims

1. An electrochemical ammonia nitrogen recovery device for high-salinity ammonia nitrogen waste liquid in a thermal power plant, characterized in that, The processing chamber, the cathode part, the anode part, the separation membrane group and the power supply part are included. The separation membrane group includes a first membrane part made of hydrophobic and air-permeable plastic material, which is arranged in the processing chamber and separates the processing chamber into a recovery chamber and a waste liquid chamber, and the waste liquid chamber stores ammonia-nitrogen waste liquid and the recovery chamber stores ammonium salt solution. The anode part is arranged in the recovery chamber, the cathode part is arranged in the waste liquid chamber, and the first membrane part is used to recover free ammonia generated in the waste liquid chamber. The power supply part is electrically connected with the cathode part and the anode part respectively. The separation membrane group further includes a second membrane part and a third membrane part. The processing chamber further includes a salt water chamber, the recovery chamber is separated from the salt water chamber by the second membrane part, and the waste liquid chamber is separated from the salt water chamber by the third membrane part. The second membrane part is used to allow anions in the salt water chamber to enter the recovery chamber and block the passage of cations. The third membrane part is used to allow cations in the waste liquid chamber to enter the salt water chamber and block the passage of anions.

2. The recycling apparatus of claim 1, wherein The waste liquid chamber has a waste liquid inlet and a waste liquid outlet, and the waste liquid inlet is higher than the waste liquid outlet in the vertical direction. The waste liquid inlet and the waste liquid outlet are provided with waste liquid covers, and the waste liquid covers are detachably connected with the waste liquid inlet and the waste liquid outlet.

3. The recycling apparatus of claim 1, wherein The recovery chamber has at least two recovery ports for circulating recovered ammonia-nitrogen. The recovery ports are provided with recovery covers, and the recovery covers are arranged one-to-one corresponding to the recovery ports and are detachably connected with the recovery ports.

4. The recycling apparatus of claim 1, wherein The power supply part has a power-on voltage greater than 2.8V.

5. The recycling apparatus of claim 1, wherein The anode part and the cathode part are both made of metal material.

6. The recycling apparatus of claim 1, wherein The pore size of the first membrane part is 0.22-1μm.

7. An electrochemical ammonia nitrogen recovery method for high-salinity ammonia nitrogen waste liquid of a thermal power plant, which is executed by using the recovery device according to any one of claims 1-6, characterized in that, The following steps are included: The ammonium salt solution is added to the recovery chamber in advance, the waste liquid containing ammonia-nitrogen is added to the waste liquid chamber, the power supply part is used to supply power to the anode part and the cathode part respectively, the cathode part electrolysis generates alkali, and the anode part electrolysis generates acid; the ammonia-nitrogen contained in the waste liquid in the waste liquid chamber is converted into free ammonia when meeting alkali, and the free ammonia enters the recovery chamber through the first membrane part and is absorbed and concentrated by the acid in the recovery chamber; The nitrogen contained in the waste liquid is reduced to ammonia when meeting alkali, and is finally absorbed and concentrated by the acid in the recovery chamber.

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