A method and apparatus for treating coking wastewater

Abstract

This invention discloses a method and apparatus for treating coking wastewater, which can comprehensively treat coking wastewater to ultimately obtain industrial raw materials such as hydrogen, ammonia, and sodium sulfate crystals, achieving the goal of resource utilization of coking wastewater. The method includes: feeding coking wastewater into an oil removal device for oil removal treatment; feeding the oil-removed coking wastewater into an equalization tank and mixing it with alkaline solution; feeding the pH-adjusted coking wastewater into an ammonia removal tower for heating and ammonia removal to obtain ammonia vapor and ammonia removal mother liquor; condensing the ammonia vapor into a condenser for ammonia recovery; feeding the ammonia removal mother liquor into a wastewater oxidation treatment and hydrogen production device to obtain slag and hydrogen; feeding the slag into a first solid-liquid separation device to obtain waste residue and a first filtrate; cooling the first filtrate in a cooler and then feeding it into a second solid-liquid separation device to obtain the cooled and precipitated sodium sulfate and a second filtrate; and returning the second filtrate to the wastewater oxidation treatment and hydrogen production device.

Description

Technical Field

[0001] This invention relates to a method for treating coking wastewater and a device for treating coking wastewater. Background Technology

[0002] During the coking process, ammonia-containing wastewater from the condensation of raw coal gas, condensate from the cooling of clean coal gas, crude benzene separation water from the separation of benzene, dust-containing wastewater from the dust removal and washing equipment, wastewater separated from the crude tar oil-water separator, and bottom water discharged from the bottom of the storage tank are produced. These waters mix together to form coking wastewater with complex composition.

[0003] The wastewater has a complex composition and high COD, but most of its organic carbon consists of stable alkanes or saturated aromatic hydrocarbons such as benzene and naphthalene. The COD to BOD ratio is significantly different, making it difficult to completely remove COD through biological treatment. Furthermore, the phenols and methylphenols in the wastewater have a strong inhibitory effect on microorganisms, requiring complex chemical pretreatment when using biological methods. The composition of typical coking wastewater is shown in Table 1.

[0004] Table 1

[0005] Serial Number Components unit content 1 CODcr mg / L 3000-5000 2 BOD5 mg / L 800-2000 3 NH3-N mg / L 150-300 4 SS (suspended solids) mg / L 150-300 5 Hydrocarbons mg / L 400-2000 6 Phenols mg / L 200-500 8 sulfides mg / L 20-50 9 pH 6-8

[0006] On the other hand, known electrochemical reactors for wastewater treatment mainly include electrocatalytic oxidation (ECO) reactors and electrocoagulation (EC) reactors. Their basic structures are similar, both containing an electrolytic cell and a DC power supply, with the anode and cathode of the electrolytic cell connected to the positive and negative terminals of the DC power supply, respectively. Their main differences lie in the electrode materials and their working mechanisms.

[0007] Electrocatalytic oxidation (EO) utilizes the oxidation of the anode (usually a titanium-based metal oxide coated electrode) and / or the generation of free radicals through an electric field to promote the oxidative decomposition of pollutants, thereby achieving wastewater treatment. It can be further divided into direct oxidation and indirect oxidation methods. Direct oxidation directly oxidizes pollutants on the anode surface to remove them. Indirect oxidation uses an electric field to decompose molecules, generating hydroxyl radicals and other oxidants, which then react with pollutants in the wastewater to remove them.

[0008] Electrocoagulation (EC) removes pollutants by dissolving metal ions in the wastewater at the anode (usually an aluminum or iron electrode), which then undergoes a hydrolysis reaction to form metal hydroxides. These metal hydroxides act as flocculants, coagulating suspended solids and colloids in the wastewater. Simultaneously, hydrogen ions at the cathode gain electrons and are reduced to hydrogen gas, which escapes as microbubbles. These microbubbles then float to the surface of the wastewater through flotation.

[0009] Currently, electrocatalytic oxidation and electrocoagulation technologies have relatively limited functions and have not yet achieved the recovery and utilization of hydrogen. Summary of the Invention

[0010] The purpose of this invention is to provide a method and equipment for treating coking wastewater, which can comprehensively treat coking wastewater and ultimately obtain industrial raw materials such as hydrogen, ammonia, and sodium sulfate crystals, thereby achieving the goal of resource utilization of coking wastewater.

[0011] In one aspect, a method for treating coking wastewater is provided, comprising: feeding coking wastewater into an oil removal device to remove oil from the coking wastewater; feeding the oil-removed coking wastewater into an equalization tank and mixing it with an alkaline solution to adjust the pH value of the oil-removed coking wastewater to 11-13; feeding the pH-adjusted coking wastewater into an ammonia removal tower for heating and ammonia removal to obtain ammonia vapor and ammonia removal mother liquor respectively; feeding the ammonia vapor into a condenser to condense it into ammonia water for recovery; feeding the ammonia removal mother liquor into a wastewater oxidation treatment and hydrogen production device to obtain slag liquid and hydrogen gas respectively; and feeding the slag liquid into a first solid waste treatment unit. The solid-liquid separation equipment obtains waste residue and a first filtrate separately; the first filtrate is fed into a cooler for cooling and then fed into a second solid-liquid separation equipment to obtain sodium sulfate precipitated from the cooling and a second filtrate separately; the second filtrate is returned to the wastewater oxidation treatment and hydrogen production equipment; wherein, the wastewater oxidation treatment and hydrogen production equipment includes an electrolytic cell, a DC power supply and a hydrogen storage tank, the anode and cathode of the electrolytic cell are respectively connected to the positive and negative terminals of the DC power supply, the anode oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode precipitates hydrogen through a cathodic electrochemical reaction and recovers it through the hydrogen storage tank.

[0012] According to an embodiment of the present invention, before the coking wastewater with adjusted pH value is fed into the deammoniation tower, the coking wastewater with adjusted pH value is preheated by passing it through a first heat exchange device; before the deammoniation mother liquor is fed into the wastewater oxidation treatment and hydrogen production equipment, the deammoniation mother liquor is cooled by passing it through the first heat exchange device; the first heat exchange device achieves the preheating of the coking wastewater with adjusted pH value and the cooling of the deammoniation mother liquor respectively through heat exchange between the indirect walls of the coking wastewater with adjusted pH value and the deammoniation mother liquor.

[0013] According to an embodiment of the present invention, during the operation of the wastewater oxidation treatment and hydrogen production equipment, a portion of the electrolyte in the electrolytic cell is extracted from the electrolytic cell and input through a pipeline into a second heat exchange device located in the deammoniation heating zone at the bottom of the deammoniation tower. After the second heat exchange device heats the coking wastewater in the deammoniation heating zone at the bottom of the deammoniation tower with the electrolyte, the cooled electrolyte output from the second heat exchange device is returned to the electrolytic cell through a pipeline, thereby forming an electrolyte circulation path.

[0014] According to an embodiment of the present invention, when the heating capacity of the ammonia removal heating zone at the bottom of the ammonia removal tower is insufficient, the auxiliary heating device of the ammonia removal heating zone at the bottom of the ammonia removal tower is turned on; otherwise, the auxiliary heating device is turned off.

[0015] According to an embodiment of the present invention, when the deammoniation tower is running, the temperature of the deammoniation heating zone at the bottom of the deammoniation tower is controlled at 60℃-65℃.

[0016] According to an embodiment of the present invention, the oil removal equipment includes an oil separator and an air flotation tank arranged sequentially. The oil separator has an inlet, a bottom outlet, and a top outlet. The air flotation tank has an overflow outlet, a liquid inlet, a liquid outlet, and an aeration device. The oil separator is connected to the air flotation tank. The top outlet of the oil separator is connected to the overflow outlet of the air flotation tank, and the bottom outlet of the oil separator is connected to the liquid inlet of the air flotation tank. A scraper conveyor is provided above the oil separator and the air flotation tank, spanning across them. When the oil removal equipment is working, the coking wastewater first enters the oil separator. In the oil separator, the upper layer of floating oil is blocked, while the bottom layer of coking wastewater enters the flotation tank through the bottom outlet. In the flotation tank, most of the suspended oil-water inclusions are broken down by dissolved air flotation. The demulsified oil floats to the top of the flotation tank with the air bubbles. Under the action of the scraper conveyor, the foam flows into the oil separator through the overflow outlet and is scraped together with the floating oil in the oil separator to the top outlet at the edge of the oil separator for discharge. The coking wastewater after oil removal flows out from the liquid outlet.

[0017] According to an embodiment of the present invention, a conical settling chamber is provided at the bottom of the electrolytic cell, and the slag liquid is output through a slag discharge port provided at the bottom of the conical settling chamber.

[0018] According to an embodiment of the present invention, the first solid-liquid separation device is a filter press. According to an embodiment of the present invention, the second solid-liquid separation device is a centrifuge.

[0019] Secondly, a coking wastewater treatment device is provided, comprising: an oil removal device for removing oil from coking wastewater; an equalization tank for mixing the oil-removed coking wastewater with an alkaline solution to adjust the pH value of the oil-removed coking wastewater to 11-13; an ammonia removal tower for heating the pH-adjusted coking wastewater to remove ammonia, thereby obtaining ammonia vapor and ammonia removal mother liquor; a condenser for condensing the ammonia vapor into ammonia water for recovery; and a wastewater oxidation treatment and hydrogen production device for oxidizing the ammonia removal mother liquor to produce hydrogen, thereby obtaining slag liquid and hydrogen gas, wherein the wastewater oxidation treatment and hydrogen production device includes an electrolyzer, a DC power supply, and a hydrogen storage tank. The anode and cathode of the electrolytic cell are connected to the positive and negative terminals of a DC power supply, respectively. The anode oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode generates hydrogen through a cathodic electrochemical reaction, which is then recovered through the hydrogen storage tank. A first solid-liquid separation device is used to separate the solid and liquid components of the slag liquid to obtain waste residue and a first filtrate, respectively. A cooler is used to cool the first filtrate to obtain cooled precipitated sodium sulfate. A second solid-liquid separation device is used to separate the solid and liquid components of the cooled first filtrate to obtain cooled precipitated sodium sulfate and a second filtrate, respectively. A reflux device is used to return the second filtrate to the wastewater oxidation treatment and hydrogen production equipment.

[0020] According to an embodiment of the present invention, the coking wastewater treatment device further includes a first heat exchange device, which is used to preheat the coking wastewater after pH adjustment and cool the deammoniation mother liquor by means of heat exchange between the coking wastewater after pH adjustment and the mother liquor after deammoniation.

[0021] According to an embodiment of the present invention, the coking wastewater treatment device further includes an electrolyte circulation path for extracting a portion of the electrolyte from the electrolytic cell and inputting it through a pipeline into a second heat exchange device disposed in the deammoniation heating zone at the bottom of the deammoniation tower. After the second heat exchange device heats the coking wastewater in the deammoniation heating zone at the bottom of the deammoniation tower with the electrolyte, the cooled electrolyte output by the second heat exchange device is returned to the electrolytic cell through a pipeline.

[0022] According to an embodiment of the present invention, the oil removal equipment includes an oil separator and an air flotation tank arranged sequentially. The oil separator has an inlet, a bottom outlet, and a top outlet. The air flotation tank has an overflow outlet, a liquid inlet, a liquid outlet, and an aeration device. The oil separator is connected to the air flotation tank. The top outlet of the oil separator is connected to the overflow outlet of the air flotation tank. The bottom outlet of the oil separator is connected to the liquid inlet of the air flotation tank. A scraper conveyor spanning the oil separator and the air flotation tank is provided above the oil separator and the air flotation tank.

[0023] According to an embodiment of the present invention, a conical settling chamber is provided at the bottom of the electrolytic cell, and the slag liquid is output through a slag discharge port provided at the bottom of the conical settling chamber.

[0024] According to an embodiment of the present invention, the first solid-liquid separation device is a filter press. According to an embodiment of the present invention, the second solid-liquid separation device is a centrifuge.

[0025] The aforementioned coking wastewater treatment method and equipment are based on improvements to an electrochemical reactor, resulting in the aforementioned wastewater oxidation treatment and hydrogen production equipment. This equipment includes an electrolyzer, a DC power supply, and a hydrogen storage tank. The anode and cathode of the electrolyzer are connected to the positive and negative terminals of the DC power supply, respectively. The anode oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode generates hydrogen through a cathodic electrochemical reaction, which is then recovered through the hydrogen storage tank. The anode of this wastewater oxidation treatment and hydrogen production equipment can oxidize the wastewater similarly to the anode of an electrocatalytic oxidation reactor, while the cathode can generate hydrogen similarly to the cathode of an electrocoagulation reactor, and the hydrogen is then stored in the hydrogen storage tank. Thus, advanced wastewater oxidation treatment and hydrogen production are simultaneously achieved.

[0026] The above-mentioned coking wastewater treatment method and equipment creatively combine oil removal equipment, equalization tank, deammoniation tower, wastewater oxidation treatment and hydrogen production equipment to comprehensively treat coking wastewater and ultimately obtain industrial raw materials such as hydrogen, ammonia water and sodium sulfate crystals, thereby achieving the goal of resource utilization of coking wastewater.

[0027] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice. Attached Figure Description

[0028] The accompanying drawings, which form part of this specification, are used to aid in understanding the invention. The contents provided in the drawings and their related descriptions in this specification can be used to explain the invention, but do not constitute an undue limitation of the invention.

[0029] Figure 1 This is a schematic diagram of a coking wastewater treatment device according to an embodiment of the present invention. Detailed Implementation

[0030] The present invention will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0031] The technical solutions and features provided in the various sections, including the following description, can be combined with each other without conflict. Furthermore, where possible, these technical solutions, features, and related combinations can be given specific technical subject matter and protected by relevant patents.

[0032] The embodiments of the present invention described below are generally only some embodiments and not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of patent protection.

[0033] Regarding the terminology and units in this specification: The terms "comprising," "including," "having," and any variations thereof in this specification, the corresponding claims, and related sections are intended to cover non-exclusive inclusion. Furthermore, other related terms and units can be reasonably interpreted based on the relevant content provided in this specification.

[0034] Figure 1 This is a schematic diagram of a coking wastewater treatment device according to an embodiment of the present invention. Figure 1 As shown, a coking wastewater treatment device includes: an oil removal device 1 for removing oil from coking wastewater; an equalization tank 2 for mixing the oil-removed coking wastewater with an alkaline solution (the alkaline solution comes from an alkaline solution tank 3) to adjust the pH value of the oil-removed coking wastewater to 11-13; an ammonia removal tower 4 for heating the pH-adjusted coking wastewater to remove ammonia, thereby obtaining ammonia vapor and ammonia removal mother liquor; a condenser 5 for condensing the ammonia vapor into ammonia water for recovery; and a wastewater oxidation treatment and hydrogen production device 6 for oxidizing the ammonia removal mother liquor and producing hydrogen, thereby obtaining slag liquid and hydrogen gas, wherein the wastewater oxidation treatment and hydrogen production device 6 includes an electrolytic cell 61, a DC power supply 62, and a hydrogen storage tank. The anode 611 and cathode 612 of the 61 are connected to the positive and negative terminals of the DC power supply 62, respectively. The anode 611 oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode 612 generates hydrogen through a cathodic electrochemical reaction and recovers it through the hydrogen storage tank. The first solid-liquid separation device 7 is used to separate the solid and liquid of the slag liquid to obtain waste residue and first filtrate, respectively. The cooler 8 is used to cool the first filtrate to obtain sodium sulfate precipitated by cooling. The second solid-liquid separation device 9 is used to separate the solid and liquid of the cooled first filtrate to obtain sodium sulfate precipitated by cooling and second filtrate, respectively. The reflux device 10 is used to return the second filtrate to the wastewater oxidation treatment and hydrogen production equipment 6.

[0035] The anode 611 of the above-mentioned wastewater oxidation treatment and hydrogen production equipment 6 can be the same as or similar to that of the electrocatalytic oxidation reactor (such as a titanium-based metal oxide coated electrode), and the cathode 612 can be the same as or similar to that of the electrocoagulation reactor.

[0036] In an optional embodiment, the above-mentioned coking wastewater treatment device may further include a first heat exchange device 10, used to preheat the pH-adjusted coking wastewater and cool the deammoniation mother liquor through heat exchange between the pH-adjusted coking wastewater and the deammoniation mother liquor. Thus, before the pH-adjusted coking wastewater is fed into the deammoniation tower 4, it is preheated by the first heat exchange device 10; simultaneously, before the deammoniation mother liquor is fed into the wastewater oxidation treatment and hydrogen production equipment 6, it is cooled by the first heat exchange device 10. This achieves the purpose of using the deammoniation mother liquor to heat and preheat the pH-adjusted coking wastewater, reducing the energy consumption of the deammoniation tower 4.

[0037] In an optional embodiment, the coking wastewater treatment device may further include an electrolyte circulation path 11, used to extract a portion of the electrolyte from the electrolytic cell 61 and input it through a pipeline into a second heat exchange device 41 located in the ammonia removal heating zone at the bottom of the ammonia removal tower 4. After the second heat exchange device 41 heats the coking wastewater in the ammonia removal heating zone at the bottom of the ammonia removal tower 4 with the electrolyte, the cooled electrolyte output by the second heat exchange device 41 is returned to the electrolytic cell 61 through a pipeline.

[0038] The electrolyte circulation path 11 includes the necessary pipelines and pumps. Since the electrolytic cell 61 converts some electrical energy into heat energy in the electrolyte during operation, raising the electrolyte temperature, the electrolyte circulation path 11 provides this heat to the deammoniation tower 4. The deammoniation tower 4 uses this heat to heat and deammonize the pH-adjusted coking wastewater. This saves on other energy consumption in the deammoniation tower 4 and also allows for temperature control of the electrolytic cell 61.

[0039] In one optional embodiment, the bottom of the ammonia removal tower 4 is provided with an ammonia removal heating zone (the bottom of the ammonia removal tower 4 is equivalent to a heating vessel). In addition to the second heat exchange device 41 mentioned above, an auxiliary heating device 42 (which can be steam heating) can also be provided. When the heating capacity of the ammonia removal heating zone at the bottom of the ammonia removal tower 4 is detected to be insufficient, the auxiliary heating device 42 of the ammonia removal heating zone at the bottom of the ammonia removal tower is turned on; otherwise, the auxiliary heating device 42 is turned off.

[0040] In one optional embodiment, the oil removal equipment 1 includes an oil separator 11 and an air flotation tank 12 arranged sequentially. The oil separator 11 has an inlet, a bottom outlet, and a top outlet. The air flotation tank has an overflow outlet, a liquid inlet, a liquid outlet, and an aeration device. The oil separator 11 is connected to the air flotation tank 12. The top outlet of the oil separator 11 is connected to the overflow outlet of the air flotation tank 12. The bottom outlet of the oil separator 11 is connected to the liquid inlet of the air flotation tank 12. A scraper conveyor 13 is provided above the oil separator 11 and the air flotation tank 12, spanning the oil separator and the air flotation tank.

[0041] When the oil removal equipment is working, the coking wastewater first enters the oil separator 11. In the oil separator 11, the upper layer of floating oil is blocked, while the bottom layer of coking wastewater enters the flotation tank 12 through the bottom outlet. In the flotation tank 12, most of the suspended oil-water inclusions are broken down by dissolved air flotation. The demulsified oil floats to the top of the flotation tank 12 with the air bubbles. Under the action of the scraper conveyor 13, the foam flows into the oil separator 11 through the overflow outlet and is scraped together with the floating oil in the oil separator 11 to the top outlet at the edge of the oil separator for discharge (discharge of crude coal tar). The coking wastewater after oil removal treatment flows out from the liquid outlet.

[0042] In one optional embodiment, the bottom of the electrolytic cell 61 is further provided with a conical settling chamber 63, and the slag liquid is discharged through a slag discharge port located at the bottom of the conical settling chamber 63. The conical settling chamber 63 facilitates the settling of solid slag in the electrolytic cell 61.

[0043] In one alternative embodiment, the first solid-liquid separation device is a filter press. The second solid-liquid separation device 9 is a centrifuge. The reflux device includes a reflux pipeline and the required pump.

[0044] The above-mentioned coking wastewater treatment device can implement the following coking wastewater treatment method, including: inputting coking wastewater into oil removal equipment 1 to remove oil from the coking wastewater; inputting the oil-removed coking wastewater into equalization tank 2 and mixing it with alkaline solution to adjust the pH value of the oil-removed coking wastewater to 11-13; inputting the pH-adjusted coking wastewater into deammoniation tower 4 for heating and deammoniation to obtain ammonia vapor and deammoniation mother liquor (the temperature of the deammoniation heating zone at the bottom of the deammoniation tower 4 can be controlled at 60℃-65℃); inputting the ammonia vapor into condenser 5 to condense it into ammonia water for recovery; inputting the deammoniation mother liquor into wastewater oxidation treatment and hydrogen production equipment 6 to obtain slag liquid and hydrogen gas respectively; inputting the slag liquid into first solid-liquid separation equipment 7 to obtain waste residue and first filtrate respectively; inputting the first filtrate into cooler 8 for cooling and then into second solid-liquid separation equipment 9 to obtain cooled and precipitated sodium sulfate and second filtrate respectively; returning the second filtrate to the wastewater oxidation treatment and hydrogen production equipment 6.

[0045] The purpose of introducing the de-oiled coking wastewater into the equalization tank 2 and mixing it with alkaline solution to adjust the pH value of the de-oiled coking wastewater to 11-13 is to cause the dissolved phenols in the wastewater to undergo acidic ionization into anions, thereby reducing their volatility, and at the same time converting the ammonium ions in the water into ammonia monohydrate.

[0046] In the aforementioned coking wastewater treatment method, in the wastewater oxidation treatment and hydrogen production equipment 6, hydrogen is generated at the cathode. When a diaphragm is installed in the wastewater oxidation treatment and hydrogen production equipment 6, hydrogen cannot enter the wastewater under the action of the diaphragm, while water and various ions in the wastewater can pass through the diaphragm and enter the cathode to maintain electrical and osmotic balance. At the anode, the wastewater is in direct contact with the anode. Sulfide ions, sulfite ions, acid-ionized phenols, anilines, organic acid radicals, and other anions in the wastewater migrate to the anode and undergo electrochemical reactions. Sulfide ions and sulfite ions are oxidized to sulfate ions at the anode. During electrolysis, the voltage at the anode is controlled to operate under a higher overvoltage to generate a certain amount of strong oxidants such as persulfate ions, atomic oxygen, and hydroxyl radicals. These oxidants undergo advanced oxidation reactions with the negatively charged organic groups enriched at the anode, ultimately oxidizing them into water and carbon dioxide.

[0047] Part of the electrolyte in electrolytic cell 61 flows out from the outlet, is pumped to the deammoniation tower by the electrolytic cell circulation pump to recover heat, and then returns to electrolytic cell 61 for circulation. As the electrolysis process proceeds, water is decomposed into hydrogen and oxygen, while sulfate ions and excess alkali added in the equalization tank accumulate in the water, maintaining a high conductivity of the liquid in the electrolytic cell to improve electrolysis efficiency. When sodium sulfate is close to saturation, part of the solution is discharged from the bottom slag outlet, and this solution is used to carry away impurities that have been mineralized and precipitated during the electrolysis process to form slag liquid.

[0048] After the sludge is filtered to remove the precipitate by a filter press, a relatively clear mixed solution of sodium sulfate and sodium hydroxide is obtained. This solution is cooled by cooler 8. Since the solution concentration of sodium sulfate changes significantly with temperature, while that of sodium hydroxide changes less, some sodium sulfate crystallizes out after cooling, while sodium hydroxide does not. The precipitated sodium sulfate crystals are separated by a centrifuge, dried, and recycled as industrial sodium sulfate. The mother liquor from the centrifuge is pumped back to the electrolytic cell 61. Since some sodium sulfate has precipitated in the mother liquor, its return to the electrolytic cell and its dissolution and mixing in the cell can reduce the sodium sulfate content in the solution, thereby offsetting the increase in sodium sulfate concentration caused by the electrolysis process, thus maintaining the sodium sulfate at a high but unsaturated concentration.

[0049] The present invention has been described above. Those skilled in the art will be able to implement the present invention based on these descriptions. All other embodiments obtained by those skilled in the art based on the foregoing content of this specification without inventive effort should fall within the scope of patent protection.

Claims

1. A method for treating coking wastewater, characterized in that: include: The coking wastewater is fed into an oil removal device to remove oil from the coking wastewater; The de-oiled coking wastewater is fed into an equalization tank and mixed with alkaline solution to adjust its pH to 11-13. The pH-adjusted coking wastewater is then fed into a deammoniation tower for heating and deammoniation, yielding ammonia vapor and deammoniation mother liquor. The ammonia vapor is condensed into ammonia water for recovery. The deammoniation mother liquor is fed into a wastewater oxidation treatment and hydrogen production unit to obtain slag and hydrogen. The slag is fed into a first solid-liquid separation unit to obtain waste residue and a first filtrate. The first filtrate is cooled in a cooler and then fed into a second solid-liquid separation unit to obtain precipitated sodium sulfate and a second filtrate. The second filtrate is returned to the wastewater oxidation treatment and hydrogen production unit. The hydrogen production equipment includes an electrolyzer, a DC power supply, and a hydrogen storage tank. The anode and cathode of the electrolyzer are connected to the positive and negative terminals of the DC power supply, respectively. The anode oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode generates hydrogen through a cathodic electrochemical reaction, which is then recovered through the hydrogen storage tank. During the wastewater oxidation treatment and operation of the hydrogen production equipment, a portion of the electrolyte in the electrolyzer is extracted and piped into a second heat exchanger located in the deammoniation heating zone at the bottom of the deammoniation tower. After the second heat exchanger heats the coking wastewater in the deammoniation heating zone at the bottom of the deammoniation tower with the electrolyte, the cooled electrolyte output from the second heat exchanger is returned to the electrolyzer through a pipeline, thus forming an electrolyte circulation path.

2. The coking wastewater treatment method as described in claim 1, characterized in that: Before the pH-adjusted coking wastewater is fed into the deammoniation tower, it is preheated by passing it through a first heat exchanger. Before the deammoniation mother liquor is fed into the wastewater oxidation treatment and hydrogen production equipment, it is cooled by passing it through the first heat exchanger. The first heat exchanger achieves preheating of the pH-adjusted coking wastewater and cooling of the deammoniation mother liquor by exchanging heat between the pH-adjusted coking wastewater and the deammoniation mother liquor through the indirect heat exchange between them.

3. The coking wastewater treatment method as described in claim 1, characterized in that: When the heating capacity of the ammonia removal heating zone at the bottom of the ammonia removal tower is insufficient, the auxiliary heating device of the ammonia removal heating zone at the bottom of the ammonia removal tower shall be turned on; otherwise, the auxiliary heating device shall be turned off.

4. The coking wastewater treatment method as described in claim 1, characterized in that: The temperature of the ammonia removal heating zone at the bottom of the ammonia removal tower is controlled at 60℃-65℃.

5. The coking wastewater treatment method as described in claim 1, characterized in that: The oil removal equipment includes an oil separator and a flotation tank arranged sequentially. The oil separator has an inlet, a bottom outlet, and a top outlet. The flotation tank has an overflow outlet, a liquid inlet, a liquid outlet, and an aeration device. The oil separator and the flotation tank are connected. The top outlet of the oil separator is connected to the overflow outlet of the flotation tank, and the bottom outlet of the oil separator is connected to the liquid inlet of the flotation tank. A scraper conveyor spanning the oil separator and the flotation tank is installed above them. The oil removal equipment is designed to... During operation, coking wastewater first enters the oil separator. In the oil separator, the upper layer of floating oil is blocked, while the bottom layer of coking wastewater enters the flotation tank through the bottom outlet. In the flotation tank, most of the suspended oil-water inclusions are broken down by dissolved air flotation. The demulsified oil floats to the top of the flotation tank with the air bubbles. Under the action of the scraper conveyor, the foam flows into the oil separator through the overflow outlet and is scraped together with the floating oil in the oil separator to the top outlet at the edge of the oil separator for discharge. The coking wastewater after oil removal treatment flows out from the liquid outlet.

6. The coking wastewater treatment method as described in claim 1, characterized in that: The bottom of the electrolytic cell is provided with a conical settling chamber, and the slag liquid is output through the slag discharge port located at the bottom of the conical settling chamber.

7. The coking wastewater treatment method as described in claim 1, characterized in that: The first solid-liquid separation device is a filter press, and the second solid-liquid separation device is a centrifugal separator.

8. A coking wastewater treatment device, characterized in that: include: Oil removal equipment is used to remove oil from coking wastewater; The system includes: an equalization tank for mixing de-oiled coking wastewater with alkaline solution to adjust the pH value of the wastewater to 11-13; a deammoniation tower for heating the pH-adjusted coking wastewater to remove ammonia, thereby obtaining ammonia vapor and deammoniation mother liquor; a condenser for condensing the ammonia vapor into ammonia water for recovery; a wastewater oxidation treatment and hydrogen production device for oxidizing the deammoniation mother liquor and producing hydrogen, thereby obtaining slag liquid and hydrogen gas, wherein the wastewater oxidation treatment and hydrogen production device includes an electrolytic cell, a DC power supply, and a hydrogen storage tank, wherein the anode and cathode of the electrolytic cell are connected to the positive and negative terminals of the DC power supply, respectively, the anode oxidizes the deammoniation mother liquor through an anodic electrochemical reaction, and the cathode generates hydrogen through a cathodic electrochemical reaction and recovers it through the hydrogen storage tank; a first solid-liquid separation device for separating the slag liquid to obtain waste residue and a first filtrate; and a cooler for cooling the first filtrate to obtain cooled and precipitated sodium sulfate. The second solid-liquid separation device is used to separate the solid and liquid components of the cooled first filtrate to obtain the cooled precipitated sodium sulfate and the second filtrate, respectively. The system also includes a reflux device for returning the second filtrate to the wastewater oxidation treatment and hydrogen production equipment; and an electrolyte circulation path for extracting a portion of the electrolyte from the electrolytic cell and inputting it through a pipeline into a second heat exchange device located in the deammoniation heating zone at the bottom of the deammoniation tower. After the second heat exchange device heats the coking wastewater in the deammoniation heating zone at the bottom of the deammoniation tower with the electrolyte, it returns the cooled electrolyte output from the second heat exchange device to the electrolytic cell through a pipeline.

9. The coking wastewater treatment device as described in claim 8, characterized in that: Also includes: The first heat exchange device is used to preheat the coking wastewater after pH adjustment and cool the deammoniation mother liquor by means of heat exchange between the indirect heat exchange between the coking wastewater after pH adjustment and the mother liquor.

10. The coking wastewater treatment device as described in claim 8, characterized in that: The oil removal equipment includes an oil separator and an air flotation tank arranged sequentially. The oil separator has an inlet, a bottom outlet, and a top outlet. The air flotation tank has an overflow outlet, a liquid inlet, a liquid outlet, and an aeration device. The oil separator is connected to the air flotation tank. The top outlet of the oil separator is connected to the overflow outlet of the air flotation tank. The bottom outlet of the oil separator is connected to the liquid inlet of the air flotation tank. A scraper conveyor spanning the oil separator and the air flotation tank is provided above them.

11. The coking wastewater treatment device as described in claim 8, characterized in that: The bottom of the electrolytic cell is provided with a conical settling chamber, and the slag liquid is output through the slag discharge port located at the bottom of the conical settling chamber.

12. The coking wastewater treatment device as described in claim 8, characterized in that: The first solid-liquid separation device is a filter press, and the second solid-liquid separation device is a centrifugal separator.

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