System and method for treating garbage leachate in garbage dump

Abstract

The invention relates to a garbage landfill leachate treatment system and method, the system comprises a leachate collection assembly and a garbage incinerator, and the leachate treatment system is used for classified storage of garbage leachate according to different time lengths. The interior of a hearth of the garbage incinerator is divided into a combustion area, a penetrating fluid spraying area and a urea spraying area in an echelon mode in the exhaust direction of smoke, the combustion area is provided with a first sensor used for outputting the total amount of nitric oxide, and a second sensor used for outputting the remaining amount of nitric oxide is arranged between the urea spraying area and the penetrating fluid spraying area. The leachate spraying area is provided with a first atomizing nozzle which is respectively connected with the long-term storage tank and the immediate storage tank, and the urea spraying area is provided with a second atomizing nozzle which is respectively connected with the urea storage tank. Based on the system, a garbage leachate treatment method is implemented, namely, the leachate is classified, stored and cultured according to different time lengths, so that the ammonia nitrogen concentration of the leachate is increased; and blending percolate according to the total amount of nitric oxide in the incinerator for denitration.

Description

Technical Field

[0001] This application belongs to the field of landfill leachate treatment technology, and specifically relates to a landfill leachate treatment system and treatment method. Background Technology

[0002] Leachate, also known as landfill leachate, is a high-concentration organic wastewater produced during the accumulation, landfilling, or compression of waste (especially kitchen waste) due to precipitation, fermentation, and its own water decomposition. It contains a large amount of ammonia nitrogen, and direct discharge can easily pollute the environment. Current methods for treating organic waste mainly involve incineration. However, because kitchen waste has a high water content and is difficult to burn, it usually requires dehydration pretreatment before being mixed with other flammable, high-heat waste for incineration. Incineration is costly, and some regions still choose to use landfilling for large quantities of kitchen waste and incineration only a small amount due to cost considerations. This increases the pressure on leachate treatment and poses a significant environmental pollution risk. Current technology involves collecting the leachate and utilizing its high ammonia nitrogen content to react with the toxic nitrogen-oxygen flue gas produced by incineration under high temperature or catalytic conditions. The leachate is then sprayed into the waste incinerator to pretreat the flue gas, reducing the nitrogen monoxide content. However, the current problem with this method is that it does not properly adjust and control the leachate or other flue gas treatment liquids according to the concentration of nitric oxide in the flue gas. This can easily lead to excessive ammonia nitrogen not reacting with nitric oxide in time, resulting in a large amount of ammonia escaping. Excessive unreacted ammonia will react with other gases in the flue gas (such as hydrogen chloride and sulfur dioxide) to form ammonium salts, which can easily cause blockage and corrosion of the exhaust pipes and atomizing devices. Summary of the Invention

[0003] Based on the aforementioned technical needs, this application provides a landfill leachate treatment system and method, which can improve the accuracy of leachate ratio control and reduce the risk of blockage and corrosion of exhaust pipes and atomizing devices caused by large amounts of ammonia escape.

[0004] To achieve the above objectives, the technical solution of this application is as follows:

[0005] A landfill leachate treatment system includes a leachate collection assembly and a landfill incinerator. The leachate collection assembly includes a landfill leachate tank, at least one long-term storage tank, and at least one near-expiration storage tank. The long-term storage tank and the near-expiration storage tank are respectively connected to the landfill leachate tank. The incinerator's furnace is divided into a combustion zone, a leachate spraying zone, and a urea spraying zone in a stepped manner along the flue gas discharge direction. The combustion zone is equipped with a first sensor for outputting the total nitrogen monoxide content. A second sensor is installed between the urea spraying zone and the leachate spraying zone for outputting the residual nitrogen monoxide content. The leachate spraying zone is equipped with a plurality of first atomizing nozzles, each of which is connected to the long-term storage tank and the near-expiration storage tank respectively via a first flow regulating pump. The urea spraying zone is equipped with a plurality of second atomizing nozzles, each of which is connected to the urea storage tank via a second flow regulating pump.

[0006] Preferably, both the long-term storage tank and the near-expiration storage tank are equipped with auxiliary fermentation units.

[0007] Preferably, the leachate collection assembly further includes an ultrafiltration unit and an emergency storage tank. The emergency storage tank is connected to the landfill infiltration tank through the ultrafiltration unit, and the first atomizing nozzles are all connected to the emergency storage tank through the first flow regulating pump.

[0008] Preferably, the combustion zone is connected to an air inlet pipe for ventilation into the combustion zone, and a third atomizing nozzle is installed inside the air inlet pipe. The third atomizing nozzle is connected to at least one of the long-term storage tank, the near-expiration storage tank, or the emergency storage tank via a third flow regulating pump.

[0009] Preferably, the temperature of the permeate spraying zone is 950℃±50℃.

[0010] Preferably, a plurality of auxiliary burners are provided at one end of the combustion zone adjacent to the permeate spray zone.

[0011] Preferably, the temperature of the urea spraying zone is 900℃±50℃.

[0012] This application also discloses a method for treating landfill leachate, used to treat landfill leachate using the aforementioned landfill leachate treatment system, comprising the following steps: S1. Classifying and storing the collected landfill leachate according to different storage durations, and obtaining the ammonia nitrogen concentration of the landfill leachate at different storage durations. S2. Within the furnace of the waste incinerator, the maximum amount of nitric oxide in the flue gas is obtained along the exhaust direction. and the amount of permeate sprayed in the permeate spraying zone Based on the formula Predict the actual ammonia nitrogen concentration of the required landfill leachate, where, This represents the correction factor for ammonia nitrogen utilization rate. This indicates the ammonia nitrogen concentration of urea. S3. Indicates the maximum spraying rate of urea; and In contrast, leachate of the appropriate type is selected and sprayed into the waste incinerator via atomization to treat the flue gas for denitrification.

[0013] Preferably, the step of classifying and storing the collected landfill leachate according to different storage times includes classifying and storing the landfill leachate separately according to storage time ≥30 days and storage time <30 days.

[0014] Preferably, the method further includes step S4: obtaining the residual amount of nitric oxide in the flue gas between the permeate spraying zone and the urea spraying zone. Based on the formula Estimate the denitrification rate based on the formula Calculate the verification ammonia nitrogen concentration in landfill leachate, based on Adjust the ammonia nitrogen concentration of the leachate injected into the waste incinerator.

[0015] By adopting the above technical solution, compared with the prior art, this application has at least the following beneficial effects:

[0016] By classifying and storing leachate according to storage duration and ammonia nitrogen concentration, the appropriate leachate can be sprayed onto the flue gas generated from waste incineration using atomized spraying based on the nitrogen monoxide content in the flue gas, and then denitrified at high temperature. This application not only rationally stores and consumes leachate, reducing the risk of leachate pollution of the ground and the risk of damage to incineration equipment due to excessive ammonia, but also provides a denitrification method and equipment structure for waste incinerators, which is beneficial to reducing the consumption of urea or other denitrification chemical products during the flue gas denitrification process. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the landfill leachate treatment system in the embodiment.

[0018] In the diagram: leachate collection assembly 10, waste infiltration tank 11, long-term storage tank 12, near-expiration storage tank 13, auxiliary fermentation unit 14, ultrafiltration unit 15, emergency storage tank 16, filter 17, waste incinerator 20, combustion zone 21, first sensor 211, air inlet duct 212, third atomizing nozzle 213, third flow regulating pump 214, auxiliary burner 215, leachate spraying zone 22, first atomizing nozzle 221, first flow regulating pump 222, urea spraying zone 23, second atomizing nozzle 231, second flow regulating pump 232, second sensor 233, urea storage tank 24. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of this application will be further described below with reference to the accompanying drawings of the embodiments, and this application is not limited to the following specific implementation methods.

[0020] It should be understood that the same or similar reference numerals in the accompanying drawings of the embodiments correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "inner," "outer," "left," "right," "front," "rear," "top," and "bottom" indicate directions or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the structure or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms describing positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limitations on this patent. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0021] The following is in conjunction with the appendix Figure 1 Specific embodiments will be described in further detail below.

[0022] This application discloses a landfill leachate treatment system, including a leachate collection component 10 and a waste incinerator 20. The leachate collection component 10 includes a landfill leachate tank 11, at least one long-term storage tank 12, and at least one short-term storage tank 13. The long-term storage tank 12 and the short-term storage tank 13 are respectively connected to the landfill leachate tank 11 through pipelines. The landfill leachate tank 11 is located below the area where waste is collected, compressed, or landfilled, or connected to a waste treatment tank (mainly used to treat domestic waste, such as kitchen waste). During the process of waste compression and landfilling, the leachate generated by the waste is collected and preliminarily filtered to increase the concentration of the leachate and prevent the leachate from flowing into the ground and causing pollution.

[0023] Specifically, the long-term storage tank 12 and the near-expiration storage tank 13 can be artificially constructed tank structures or manually openable or sealable tanks or other containers, such as anaerobic storage tanks. Filters 17 are installed on the connecting pipelines to the landfill infiltration tank 11 for coarse filtration. Reverse osmosis membranes and other technologies are used to further reduce the moisture content of the leachate and increase the concentration of the leachate in the storage tanks. Each storage tank is equipped with a leachate collection pump to provide a negative pressure environment, improving the collection efficiency of the landfill leachate and preventing pipeline blockage. In some embodiments, the landfill infiltration tank 11 is established based on a landfill recycling station in a certain area (urban area), and there can be more than one, with multiple interconnected areas allowed. The long-term storage tank 12 and the near-expiration storage tank... Multiple leachate pools 13 can be built around the landfill leachate pool 11. Among them, the long-term storage pool 12 can prioritize collecting leachate from landfilled waste that has been stored for a long time (such as waste that has been stored for a long time in some recycling stations due to limited landfill or incineration efficiency). This part of the leachate has a long natural fermentation time and sufficient oxidation, and can continue to be stored for a long time to significantly increase its ammonia nitrogen content. The near-expiration storage pool 13 can prioritize collecting leachate formed in a short time from waste with a short storage time and high water content. Although this part of the leachate has a short natural fermentation time and low ammonia nitrogen content, it is large in quantity and urgently needs to be diverted from the landfill leachate pool 11. However, after collection, anaerobic treatment or fermentation adjustment can also increase its ammonia nitrogen content in a short period of time.

[0024] The furnace of the waste incinerator 20 is divided into a combustion zone 21, a permeate spray zone 22, and a urea spray zone 23 in a stepped manner along the flue gas discharge direction. The combustion zone 21 is connected to the waste inlet of the waste incinerator 20 and is mainly used for igniting and incinerating waste. It is not only the area with the highest temperature in the furnace (the furnace temperature of some power incinerators that can be used for power generation can be raised to over 1000℃, such as mechanical grate furnaces and fluidized bed incinerators), but also the area where nitric oxide is concentrated. The combustion zone 21 is equipped with a first sensor 211, which includes an integrated nitric oxide concentration sensor. After high-temperature protection treatment, it can monitor the concentration of nitric oxide in the flue gas generated in the combustion zone 21 in real time and the flue gas flow rate. The two are automatically multiplied under the corresponding program to obtain the total amount of nitric oxide in real time (per unit time, such as per minute or per hour). The permeate spray zone 22 is equipped with several first atomizing nozzles 221. In some different embodiments, multiple first atomizing nozzles 221 can be evenly distributed around the circumference of the leachate spraying zone 22, or multiple sets can be arranged in a tiered manner along the flue gas discharge direction within the leachate spraying zone 22. The first atomizing nozzles 221 are all connected to the long-term storage tank 12 and the near-term storage tank 13 through the first flow regulating pump 222. By installing a solenoid valve on the connecting pipeline, the connection between the near-term storage tank 13 or the long-term storage tank 12 can be determined based on the total amount of nitrogen monoxide that needs to be denitrified. This allows leachate with different ammonia nitrogen concentrations to be fully atomized by the first atomizing nozzles 221 and sprayed into the flue gas. The high temperature and residual heat of the flue gas cause the ammonia nitrogen to react with the nitrogen monoxide, thus performing preliminary denitrification treatment on the flue gas. At the same time, the leachate is treated, avoiding its waste or pollution of the surface environment. The first flow regulating valve can adjust and set the supply flow rate of the leachate according to the total amount of nitrogen monoxide and the ammonia nitrogen concentration.

[0025] A second sensor 233 is installed between the urea spray zone 23 and the leachate spray zone 22. This second sensor 233 can be configured in the same way as the first sensor 211, and is used to obtain the residual nitrogen monoxide in the flue gas after leachate treatment. To reduce pollution caused by the emission of residual nitrogen monoxide into the atmosphere, several second atomizing nozzles 231 are installed in the urea spray zone 23. In a specific embodiment, the number or structural layout of the second atomizing nozzles 231 can refer to the first atomizing nozzle 221 described above, and will not be repeated here. All second atomizing nozzles 231 are connected to the urea storage tank 24 via a second flow regulating pump 232. The urea storage tank 24 contains sufficient urea. The second flow regulating pump 232 can adjust the urea supply flow rate according to the ammonia nitrogen concentration and residual nitrogen monoxide in the urea, so that the second atomizing nozzles 231 fully atomize the urea and spray it into the flue gas. Combined with the leachate, this continuously denitrifies the flue gas, reducing nitrogen monoxide emissions. In other embodiments, the layout of the above-mentioned permeate spraying zone 22 and urea spraying zone 23 can be changed or adapted according to the structure of the incinerator, the temperature distribution of the furnace or the temperature distribution of the flue gas emission structure, so as to facilitate denitrification treatment.

[0026] Using the above processing system has at least the following beneficial effects:

[0027] By classifying and storing leachate according to storage duration and ammonia nitrogen concentration, the appropriate leachate can be sprayed onto the flue gas generated from waste incineration using atomized spraying based on the nitrogen monoxide content in the flue gas, and then denitrified at high temperature. This application not only rationally stores and consumes leachate, reducing the risk of leachate pollution of the ground and the risk of damage to incineration equipment due to excessive ammonia, but also provides a denitrification method and equipment structure for waste incinerators, which is beneficial to reducing the consumption of urea or other denitrification chemical products during the flue gas denitrification process.

[0028] Based on the above embodiments, this application also provides some specific implementation methods to improve the above solutions.

[0029] To accelerate the decomposition of organic nitrogen in landfill leachate and increase ammonia nitrogen concentration, both the long-term storage tank 12 and the near-expiration storage tank 13 are equipped with auxiliary fermentation units 14. Specifically, in addition to removing impurities from the landfill leachate, different auxiliary fermentation units 14 can independently or comprehensively provide a fermentation environment to increase the ammonia nitrogen generation rate. These auxiliary fermentation units 14 include, but are not limited to, one or more combinations of equipment such as anaerobic bacterial agent quantitative dosing devices, leachate stirring reactors, and storage container temperature regulating reactors to conduct auxiliary fermentation of the landfill leachate in the tanks to different degrees. Based on ammonia nitrogen concentration requirements and cost requirements, the ammonia nitrogen concentration of the landfill leachate in different storage tanks is increased to different levels. Furthermore, to prevent large amounts of hazardous gases such as methane and hydrogen sulfide generated in the fermentation environment from entering the high-temperature environment of the furnace, gas collection and treatment devices are also required in the gas accumulation areas of the long-term storage tank 12, the near-expiration storage tank 13, and the landfill leachate tank 11. This prevents the leakage of flammable and explosive gases and reduces the gas pressure in the storage tanks, facilitating the pumping out of the landfill leachate.

[0030] In one embodiment, the leachate collection assembly 10 further includes an ultrafiltration unit 15 and an emergency storage tank 16. The specific structure of the emergency storage tank 16 can be referenced from the long-term storage tank 12 and the near-expiration storage tank 13. The emergency storage tank 16 is connected to the landfill infiltration tank 11 through the ultrafiltration unit 15. The ultrafiltration unit 15 further reduces the water content in the leachate through pressure difference, assisting the leachate entering the emergency storage tank 16 to rapidly increase the ammonia nitrogen concentration, so as to be used when the leachate in the long-term storage tank 12 is insufficient. In some embodiments, multiple emergency storage tanks 16 can also be set around the landfill infiltration tank 11 to provide emergency treatment of landfill leachate when the landfill infiltration tank 11, the long-term storage tank 12, and the near-expiration storage tank 13 are all overfilled. Due to the high maintenance cost of the ultrafiltration unit 15, the emergency storage tank 16 is only activated as a backup solution for the above reasons. The water filtered by the ultrafiltration unit 15 has a low content of impurities and pollutants and can be directly used in irrigation, greening maintenance, etc., or returned to the urban water supply network after treatment to achieve the effect of energy conservation and emission reduction.

[0031] Furthermore, to enhance the limiting effect of combustion zone 21 on the nitrogen monoxide content in the generated flue gas, combustion zone 21 is connected to air inlet pipe 212. Air inlet pipe 212 is a ventilation pipe of the air intake system of waste incinerator 20. One end of it is connected to a fan to ventilate and supply oxygen to the incinerator so that the waste can be fully combusted. A third atomizing nozzle 213 is installed in air inlet pipe 212. The third atomizing nozzle 213 is connected to at least one of long-term storage tank 12, near-expiration storage tank 13 or emergency storage tank 16 through a third flow regulating pump 214. When using this system, during the process of supplying air to the furnace through the air inlet pipe 212 to ignite the waste or increase the combustion temperature, any valve between the third atomizing nozzle 213 and each storage tank and the third flow regulating pump 214 are opened to atomize the leachate through the nozzles and allow it to enter the combustion zone 21 with the ventilation airflow at a set flow rate. The leachate is fully dispersed in the large space of the combustion zone 21 with the airflow and releases ammonia nitrogen, thus pre-denitrifying the flue gas generated in the combustion zone 21 before the first and second atomizing nozzles 231. In one embodiment, the waste incinerator 20 is preferably a mechanical grate furnace. In this mechanical grate furnace, a rotatable grate is distributed along the combustion zone 21 in the furnace. The gaps between the grates form air inlets. The grates rotate so that the waste is burned and discharged from the furnace during the transfer process. Each air inlet forms multiple ventilation spaces below the grate, which are connected to multiple air inlet pipes 212. Each air inlet pipe 212 can be equipped with a third atomizing nozzle 213. When in use, the leachate can be introduced into the combustion zone 21 through the air inlet pipe 212 to pre-denitrify the flue gas. When the aerosol formed by the leachate passes through the grate gap, its water content can be used to cool the grate through evaporation, which can extend the life of the metal grate in a high-temperature oxidizing environment, reduce maintenance costs, and improve the efficiency of waste incineration.

[0032] It should be noted that, due to the high temperature in the combustion zone 21, in order to avoid excessive ammonia nitrogen being oxidized into nitrous oxide at high temperatures and exacerbating the greenhouse effect, the spraying of leachate in the air inlet duct 212 should be carried out intermittently, and the flow rate and frequency should be strictly limited.

[0033] Furthermore, in order to ensure that the leachate sprayed in the leachate spraying zone 22 can release ammonia and react fully with nitric oxide under high temperature conditions, thereby avoiding or reducing the cost of using catalysts, the temperature of the leachate spraying zone 22 should be within the range of 950℃±50℃.

[0034] To enable the permeate to efficiently form ammonia and react with nitric oxide and oxygen to produce nitrogen and water under catalyst-free conditions, this application simulated high-temperature reaction conditions and obtained the denitrification efficiency results corresponding to the effective temperature range as shown in the table below:

[0035] Temperature range Reaction characteristics Denitrification efficiency main byproducts 850℃~900℃ The permeate has a low efficiency in decomposing ammonia gas and a low reaction rate. 10%～15% small amount 900℃~950℃ The efficiency of ammonia decomposition by the permeate was significantly improved, and the reaction rate gradually increased with increasing temperature. 15%～30% none 950℃~1000℃ The efficiency of the permeate in decomposing ammonia gradually reaches its peak, and the rate of increase in reaction rate gradually decreases with temperature. 30%～40% small amount (follow) (Excessive amounts show an increasing trend) >1000℃ Rapid pyrolysis of the filtrate leads to incomplete reaction and unstable reaction rate. 10%~20% , (High temperature caused) The reverse reaction should be oxidized to )

[0036] As shown in the table above, the efficiency of ammonia generation from permeate pyrolysis and the denitrification efficiency are expected to reach their optimal levels under catalytic-free conditions within a temperature range of 950℃±50℃. To avoid generating byproducts that reduce the denitrification effect, the permeate atomization flow rate should be strictly controlled to prevent excessively high ammonia nitrogen concentrations and excessively rapid pyrolysis due to high temperatures, which could lead to delayed reactions between ammonia and nitric oxide. For a conservative approach, the first flow regulating pump 222 should be started to spray the permeate when the temperature in the permeate spraying zone 22 reaches 950℃.

[0037] Furthermore, to ensure that the flue gas temperature in the permeate spray zone 22 can quickly reach 950℃ and to avoid rapid temperature loss during flue gas flow, several auxiliary burners 215 are installed at one end of the combustion zone 21 adjacent to the permeate spray zone 22. The auxiliary burners 215 include a pressurized gas supply system and an ignition system, which can increase the oxygen content in the flue gas and compensate for the temperature loss. Specifically, the auxiliary burners 215 can be evenly distributed around the top of the combustion zone 21 to increase the ignition area, or they can be distributed in a stepped manner along the flue gas discharge direction, referencing the distribution of each group of atomizing nozzles, to achieve continuous heating and prevent the flue gas from overheating, ensuring a suitable temperature for the denitrification reaction.

[0038] Finally, the temperature of the urea spray zone 23 is controlled within the range of 900℃±50℃. The reason is as follows: In the embodiment where the urea spray zone 23 is located above the leachate spray zone 22, referring to the temperature control range of the leachate spray zone 22 mentioned above, since urea has a lower water content and a higher ammonia nitrogen concentration (purer) than leachate, under the premise of fewer impurities, urea of ​​the same concentration is more likely to thermally decompose and release ammonia gas than leachate. Moreover, the temperature of the flue gas is slightly reduced (relatively reduced by 5% to 10%) when passing through the urea spray zone 23 compared to the leachate spray zone 22, resulting in a relatively lower flue gas flow rate, which makes it easier for ammonia gas to react with nitric oxide and achieve a higher reaction efficiency. Based on this, with reference to the optimal temperature of the permeate spray zone 22, the temperature of the urea spray zone 23 can be controlled to reach 900℃±50℃. Experiments show that when the ammonia nitrogen concentration is adjusted to the optimal parameters, the denitrification efficiency achieved by the rapid decomposition of urea into ammonia gas within this temperature range is up to 70%. Based on the denitrification effect already achieved by the permeate, further denitrification treatment of the flue gas using urea can make the overall denitrification efficiency no less than 90%.

[0039] Based on the above system, if applied properly, the following effects can be achieved: When the total amount of nitrogen monoxide in the flue gas produced by incinerating waste at different stages or from incinerating different types of waste changes, different types of leachate (with different storage periods) can be selected to perform preliminary denitrification of the flue gas. While treating a portion of the leachate, the ammonia content in the denitrification reaction can be controlled relatively precisely, avoiding excessive ammonia or the generation of large amounts of byproducts that would worsen the pollution of the flue gas. Furthermore, excessive leachate can be avoided from causing corrosion and blockage of the furnace body, nozzles, and other equipment due to excessive crystalline salts generated after evaporation. The system also utilizes urea for efficient denitrification of the remaining flue gas, consuming a large amount of nitrogen monoxide. This application aims to reduce the cost of urea use and the pollution risk of byproducts, and to maximize the utilization rate of leachate, truly aligning with the environmental protection concepts of energy conservation, emission reduction, and waste utilization.

[0040] In addition to the above, this application also discloses a method for treating landfill leachate, which can be applied to the above-mentioned treatment system to properly treat landfill leachate.

[0041] The specific implementation steps of this method are as follows:

[0042] 1. Collected landfill leachate was classified and stored according to different storage durations, and the ammonia nitrogen concentration of the leachate was obtained for each storage duration. .

[0043] The specific steps for implementing this procedure are as follows:

[0044] The total amount and rate of leachate formation vary depending on the processing capacity of the waste treatment plant, the proportion of kitchen waste in the waste to be treated (which determines key factors such as ammonia nitrogen content, moisture content, and self-fermentation speed), and the waste treatment method (compression, stockpiling, anaerobic landfill, etc.). For example, in a certain area, there is a large amount of domestic waste, but the scale of the waste treatment plant is small, resulting in a slow processing speed. The waste cannot be incinerated in time and can only be stockpiled for a longer period of time. As the stockpiling volume and stockpiling time increase, the production of leachate increases and it is necessary to divert and store it. However, this part of the leachate may not have enough fermentation time due to the low content of kitchen waste and the fact that it has not been treated by compression and anaerobic landfill (usually the ammonia nitrogen concentration of this part of the leachate is far below 50 mg / L). For this portion of leachate, it can be coarsely filtered and temporarily stored. Multiple storage spaces can be set up around the relevant recycling station, such as anaerobic digesters and near-expiration storage tanks, for timely storage. Simultaneously, to facilitate retrieval, this portion of leachate should be stored for a short period and subjected to low-cost inputs such as temperature regulation and the addition of fermentation aids to quickly raise the ammonia nitrogen concentration to a usable range, allowing for rapid use and emptying some space to continuously accommodate the continuously generated leachate. For leachate intended for long-term anaerobic landfill treatment or that contains a large proportion of kitchen waste and has a relatively long production period, it possesses a higher baseline ammonia nitrogen concentration and a higher degree of decomposition (typically...). (Some permeate has an ammonia nitrogen concentration higher than 100 mg / L. Due to the high impurity content, significant hazard, and slow formation of this permeate, a relatively long-term storage treatment can be implemented to address flue gas with low total nitrogen monoxide content. This treatment process requires higher input costs compared to short-term storage of permeate. For example, a collection tank equipped with methane collection and reaction treatment equipment can be used to improve the safety level. By storing this permeate for a longer period, it can undergo deeper fermentation to achieve a higher ammonia nitrogen concentration. After long-term storage, it can be applied to flue gas with low total nitrogen monoxide content to achieve better denitrification effects compared to short-term permeate.)

[0045] The ammonia nitrogen concentration of the permeate stored for different durations was monitored in real time. After sampling, the pH of the samples was adjusted to alkaline, the ammonia was distilled off, absorbed with boric acid, and titrated with hydrochloric acid. The ammonia nitrogen concentration was calculated by recording the titration loss (the detection method is existing technology and will not be described in detail in this application).

[0046] Specifically, permeate formed under the above-mentioned different conditions is divided into two categories for storage: permeate requiring near-term storage is stored for <30 days; permeate requiring long-term storage is stored for ≥30 days. This classification method is derived from the following experimental results:

[0047] Let A be the long-term osmotic solution and B be the near-term osmotic solution. Both were stored for 90 days, and the ammonia nitrogen concentration and pH value were recorded at different stages. The results are shown in the table below: (Note: Table 1 shows the culture results of osmotic solution A, and Table 2 shows the culture results of osmotic solution B)

[0048] Time range (days) Ammonia nitrogen concentration (mg / L) pH 0~30 100~200 6~7 30~60 200~600 5~6 60~90 600~2000+ 4~6

[0049] surface

[0050] Time range (days) Ammonia nitrogen concentration (mg / L) pH 0~30 20~60 5~6 30~60 60~150 6~7 60~90 150~500 7~8

[0051] surface

[0052] As shown in the table above, under the same anaerobic culture environment and culture time, the ammonia nitrogen concentration of type B permeate is lower than that of type A permeate due to its formation factors, and the efficiency of ammonia nitrogen generation is slower. Furthermore, its fermentation cost gradually increases over time. Due to limitations in storage costs and the yield of type B permeate, it is difficult to store it for a long period at a low cost. Therefore, type B permeate is stored near its expiration date for less than 30 days to facilitate timely processing. For type A permeate, the ammonia nitrogen concentration increases significantly with storage time and fermentation costs (after fermentation time exceeds 30 days). Since type A permeate has a longer collection time, it can be used in conjunction with type B permeate for flue gas denitrification. Therefore, to obtain permeate with different ammonia nitrogen concentrations, it is stored for a long period of no less than 30 days.

[0053] 2. Detect the maximum amount of nitrogen monoxide in the furnace of waste incinerator 20 along the flue gas discharge direction. (This value represents the total nitric oxide content) and the amount of permeate sprayed within the permeate spraying zone 22. (This is usually determined by the flow rate of the first flow regulating pump 222 in the above system under normal operating conditions), through the formula. Predict the actual ammonia nitrogen concentration of the required landfill leachate ,in, This represents the correction factor for ammonia nitrogen utilization rate. This indicates the ammonia nitrogen concentration of urea. This indicates the maximum spraying volume of urea (determined by the flow rate of the second flow regulating pump 232 in the above system under normal operating conditions).

[0054] Specifically, in the above steps The first sensor 211 of the aforementioned system can obtain the maximum concentration of nitric oxide in the flue gas from the combustion zone 21 to the permeate spray zone 22. (Unit: mg / ) and flue gas flow rate (unit: ), based on formula calculate ; The value is then obtained through the formula calculate, The experimental method for the value example is roughly as follows: following the process of preparing the experimental furnace to simulate the incineration experiment as described above, standard oxygen is introduced into the experimental furnace. Gas (300mg / ), control the temperature at 950℃, and maintain a constant flow rate (e.g., 10). Atomized particle size 50 Injection pressure 1 Spraying permeate into the furnace and measuring the outlet Concentration changes, assuming the amount of ammonia nitrogen and the consumption of nitric oxide are... (This ratio is used as an example only in this application and does not represent an empirical value from actual experiments), and The experimental data examples are as follows:

[0055] Ammonia nitrogen concentration in the osmotic fluid (mg / L) Nitric oxide removal (mg / ) ) value 1000 50 0.4 2000 120 0.7 3000 175 0.65

[0056] The calibration result is The value range is 0.6 to 0.7 (high ammonia nitrogen permeate has a higher utilization rate).

[0057] 3. Based on step 2 above, obtain the actual ammonia nitrogen concentration required for denitrification. Ammonia nitrogen concentration in different types of permeate Comparison: Select ammonia nitrogen concentration that is closer to or greater than [the specified concentration]. The permeate from the storage tank is sprayed into the permeate spraying zone 22 to treat the flue gas for denitrification.

[0058] Specifically, the above steps are simulated experimentally.

[0059] Experiment Example 1: Leachate was collected and classified. The ammonia nitrogen concentration in Class A leachate was found to be 2200 mg / L, and in Class B leachate it was 50 mg / L. Nitric oxide at a concentration of 200 mg / L was introduced into the experimental furnace. The nitric oxide flow rate is 1000 , The value is set to 0.7, the concentration of ammonia nitrogen in the urea used is 10000 mg / L, and the urea spray volume is 5. The permeate spray volume is 100 Calculated using the formula in step one =2357mg / L. Given that the concentration of Class A permeate is 2200mg / L, based on the predicted actual ammonia nitrogen concentration, Class A permeate should be preferred for denitrification pretreatment of nitric oxide in order to maximize the beneficial effects of the above system.

[0060] In addition to the steps described above, the method also includes step 4, obtaining the residual amount of nitric oxide in the flue gas between the permeate spray zone 22 and the urea spray zone 23. Based on the formula Estimate the denitrification capacity of landfill leachate, and then based on the formula. Calculate the verification ammonia nitrogen concentration in landfill leachate, based on Adjust the ammonia nitrogen concentration of the leachate injected into the waste incinerator 20.

[0061] Specifically, step 4 is simulated based on the above experimental example.

[0062] Experiment Example 2: Detecting the residual amount of nitric oxide in flue gas based on the second sensor 233 in the experimental system. The remaining concentration of nitric oxide =160mg / Nitric oxide residual flow rate =300 Calculated =152000 mg / h, =2171 mg / L, from which the reconfirmed ammonia nitrogen concentration can be determined. <Actual ammonia nitrogen concentration (Predicted value in step 2) If the leachate from step 2 is used to pre-denitrify the flue gas, the expected denitrification effect can be achieved.

[0063] The above experiments at least verify that if this method is applied to the above system, it can replace urea with leachate to achieve a better denitrification effect on flue gas from waste incineration, provided that the leachate is properly stored, thereby reducing the cost of flue gas denitrification.

[0064] Obviously, the above embodiments of this application are merely examples for clearly illustrating this application, and are not intended to limit the implementation of this application. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A landfill leachate treatment system, characterized in that, The system includes a leachate collection assembly and a waste incinerator. The leachate collection assembly includes a waste infiltration tank, at least one long-term storage tank, and at least one near-expiration storage tank. The long-term storage tank and the near-expiration storage tank are respectively connected to the waste infiltration tank. The furnace of the waste incinerator is divided into a combustion zone, a leachate spraying zone, and a urea spraying zone in a stepped manner along the flue gas discharge direction. The combustion zone is equipped with a first sensor for outputting the total amount of nitrogen monoxide. A second sensor is installed between the urea spraying zone and the leachate spraying zone for outputting the residual amount of nitrogen monoxide. The leachate spraying zone is equipped with a plurality of first atomizing nozzles, each of which is connected to the long-term storage tank and the near-expiration storage tank respectively through a first flow regulating pump. The urea spraying zone is equipped with a plurality of second atomizing nozzles, each of which is connected to the urea storage tank through a second flow regulating pump.

2. The landfill leachate treatment system as described in claim 1, characterized in that, Both the long-term storage tank and the near-expiration storage tank are equipped with auxiliary fermentation units.

3. The landfill leachate treatment system as described in claim 1, characterized in that, The leachate collection assembly also includes an ultrafiltration unit and an emergency storage tank. The emergency storage tank is connected to the landfill infiltration tank through the ultrafiltration unit, and the first atomizing nozzles are all connected to the emergency storage tank through the first flow regulating pump.

4. The landfill leachate treatment system as described in claim 3, characterized in that, The combustion zone is connected to an air inlet pipe, which is used to ventilate the combustion zone. A third atomizing nozzle is installed inside the air inlet pipe, and the third atomizing nozzle is connected to at least one of the long-term storage tank, the near-expiration storage tank, or the emergency storage tank through a third flow regulating pump.

5. The landfill leachate treatment system as described in claim 1, characterized in that, The temperature of the permeate spraying zone is 950℃±50℃.

6. The landfill leachate treatment system as described in claim 5, characterized in that, Several auxiliary burners are provided at one end of the combustion zone adjacent to the permeate spray zone.

7. The landfill leachate treatment system as described in claim 1, characterized in that, The temperature of the urea spraying zone is 900℃±50℃.

8. A method for treating leachate from a landfill, characterized in that, The system applied to the landfill leachate treatment system as described in any one of claims 1 to 7 includes the following steps: S1. The collected leachate is classified and stored according to different storage durations, and the ammonia nitrogen concentration of the leachate is obtained for each storage duration. ; S2. Within the furnace of the waste incinerator, the maximum amount of nitrogen monoxide in the flue gas is obtained along the exhaust direction. and the amount of permeate sprayed in the permeate spraying zone Based on the formula Predict the actual ammonia nitrogen concentration of the required landfill leachate, where, This represents the correction factor for ammonia nitrogen utilization rate. This indicates the ammonia nitrogen concentration of urea. This indicates the maximum spraying volume of urea; S3. Based on and In contrast, leachate of the appropriate type is selected and sprayed into the waste incinerator via atomization to treat the flue gas for denitrification.

9. The landfill leachate treatment method as described in claim 8, characterized in that, The method of classifying and storing the collected landfill leachate according to different storage durations includes classifying and storing the landfill leachate separately according to storage time ≥30 days and storage time <30 days.

10. The landfill leachate treatment method as described in claim 8, characterized in that, It also includes step S4. Obtaining the residual amount of nitric oxide in the flue gas between the permeate spray zone and the urea spray zone. Based on the formula Estimate the denitrification rate based on the formula Calculate the verification ammonia nitrogen concentration in landfill leachate, based on Adjust the ammonia nitrogen concentration of the leachate injected into the waste incinerator.

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