Full-quantitative treatment system and method for landfill leachate

Abstract

The invention discloses a full-quantitative treatment system and method for landfill leachate. The full-quantitative treatment system comprises a membrane treatment unit, a first-stage decrement unit, a second-stage decrement unit, a stage decrement unit, a back-spraying unit and an organic Rankine cycle unit, the invention discloses a full-quantitative treatment method for landfill leachate. Concentrating the landfill leachate by using a membrane treatment unit to obtain a membrane concentrated solution; the obtained membrane concentrated solution is introduced into a first-stage decrement unit and subjected to low-concentration-ratio treatment, and the treated membrane concentrated solution is sprayed back to a hearth or flows into a second-stage decrement unit through a back-spraying unit; the second-stage decrement unit is used for carrying out medium concentration ratio treatment on the membrane concentrated solution, and the treated membrane concentrated solution is sprayed back to the hearth or flows to the third-stage decrement unit through the back-spraying unit; the third-stage reduction unit is used for carrying out high-concentration-ratio treatment on the membrane concentrated solution, and the treated membrane concentrated solution is sprayed back to the hearth through the back-spraying unit.

Description

Technical Field

[0001] The invention relates to the technical field of landfill leachate treatment, and in particular to a fully quantitative landfill leachate treatment system and method. Background Art

[0002] Landfill leachate membrane concentrate is the residual liquid intercepted by reverse osmosis (RO) membrane or nanofiltration (NF) membrane after biodegradation of landfill leachate. It is a toxic and harmful pollutant with poor biodegradability, bioaccumulation and three-cause effects. It contains a large number of difficult-to-degrade organic substances such as alkanes, benzene series, lipids, carboxylic acids, many of which are artificially synthesized and contain a large number of toxic substances and carcinogens. Heavy metals such as Fe, Zn, and Hg in the membrane concentrate will bioaccumulate after entering the human body, causing damage to the immune system, organs and nervous system, and inducing cell mutation and cancer. Therefore, it is very necessary to fully quantify and harmlessly treat the membrane concentrate.

[0003] Full quantification means that the leachate and membrane concentrate are completely treated without producing concentrate or residue that requires further disposal, thus achieving zero discharge and harmless treatment of leachate and related waste liquids.

[0004] Therefore, the full quantification and harmless treatment of membrane concentrate is the key and difficulty to ensure that the leachate is discharged in the whole process and meets the pollution control standards for sanitary landfill of domestic waste. If the treatment problem of membrane concentrate is not solved, the full quantification and harmless treatment of leachate cannot be achieved. At present, the conventional treatment methods of membrane concentrate of garbage leachate include reinjection method, solidification method, advanced oxidation method, incineration method and evaporation method. Back-spray incineration is to spray the membrane concentrate back into the incinerator and use the high temperature in the furnace to incinerate the organic matter in the membrane concentrate at high temperature. This method has the advantages of good treatment effect, low cost and high degree of harmlessness. During the back-spray incineration process, the membrane concentrate absorbs the combustion heat during the heating and evaporation process, which reduces the heat load of the furnace and alleviates the risk of slagging on the water-cooled wall; the flue gas after incineration and the flue gas in the furnace can share the tail flue gas treatment equipment, which reduces the investment cost.

[0005] However, during the back-spray incineration process, the back-spray volume of the membrane concentrate and the concentration level of the membrane concentrate itself will affect the normal operation of the incinerator, and the back-spray leachate needs to be reduced. However, when the existing back-spray incineration method for membrane concentrate cannot achieve the back-spray leachate reduction treatment, the boiler cannot back-spray or the back-spray volume is limited, the leachate will continue to accumulate and cannot be fully treated.

[0006] Therefore, the current leachate back-spraying treatment process of municipal solid waste incineration plants has the above-mentioned shortcomings, and there is still a need for further optimization in terms of leachate resource utilization, low-carbon greenness and treatment costs. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a fully quantitative treatment system and method for landfill leachate, so as to solve the problem that landfill leachate in existing domestic waste incineration plants cannot be reduced in volume during back-spray incineration.

[0008] First, the present invention provides a fully quantitative treatment system for landfill leachate, the fully quantitative treatment system comprising:

[0009] A membrane treatment unit, wherein the membrane treatment unit is used to concentrate the landfill leachate to obtain a membrane concentrate from the landfill leachate;

[0010] A primary reduction unit, the primary reduction unit comprising a preheater and a booster fan connected to the preheater, the booster fan being connected to a flue pipe, and the preheater being connected to the membrane treatment unit;

[0011] A secondary reduction unit, the secondary reduction unit comprising an MVR evaporator and a steam-electric dual-drive compressor connected to the MVR evaporator, the MVR evaporator being connected to the preheater;

[0012] A three-stage reduction unit, the three-stage reduction unit includes a submerged combustion evaporator, the submerged combustion evaporator is connected to the MVR evaporator;

[0013] A back-spray unit, the back-spray unit comprising a booster pump, an induced draft fan and a cooler, the cooler being connected to the induced draft fan, the booster pump being connected to the preheater, the MVR evaporator and the submerged combustion evaporator, and the cooler being connected to the preheater, the MVR evaporator and the submerged combustion evaporator;

[0014] An organic Rankine cycle unit, the organic Rankine cycle unit is connected to the steam-electric dual-drive compressor to provide power to the steam-electric dual-drive compressor;

[0015] The flue pipe is connected to a chimney in a waste incineration plant, the chimney provides flue gas to the preheater through the flue pipe, and the organic Rankine cycle unit obtains heat from the flue pipe.

[0016] Preferably, the membrane treatment unit comprises an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane, the landfill leachate is concentrated through the ultrafiltration membrane, the nanofiltration membrane and the reverse osmosis membrane in sequence, and the nanofiltration membrane and the reverse osmosis membrane are respectively connected to the water system.

[0017] Preferably, the organic Rankine cycle unit includes an evaporator, a condenser, a regenerator, a circulating pump, a turbine and a synchronous motor, the synchronous motor is connected to the turbine, the turbine is connected to the steam-electric dual-drive compressor, the evaporator is connected to the regenerator, the regenerator is connected to the condenser, the condenser and the regenerator are both connected to the circulating pump, the condenser and the regenerator are both connected to the turbine; the evaporator is connected to the flue pipe.

[0018] Preferably, a first valve is connected to the flue pipe.

[0019] Preferably, a first back-spray pipeline is connected between the preheater and the booster pump, and a second valve, a third valve and a fourth valve are connected to the first back-spray pipeline;

[0020] A second back-spray pipeline is connected between the preheater and the MVR evaporator, and a fifth valve is connected to the second back-spray pipeline;

[0021] A third return spray pipeline is connected between the MVR evaporator and the submerged combustion evaporator, and a sixth valve is connected to the third return spray pipeline.

[0022] Preferably, the water inlet of the cooler is connected to the water outlet of the reverse osmosis membrane, the water outlet of the cooler is connected to the preheater, a seventh valve is connected between the water outlet of the cooler and the preheater, and the water outlet of the cooler is also connected to the water inlet of the nanofiltration membrane.

[0023] Preferably, an eighth valve is connected between the MVR evaporator and the cooler; the MVR evaporator is connected to a water outlet pipe, the water outlet pipe is connected to the water inlet end of the nanofiltration membrane, and the water outlet pipe is connected to a ninth valve.

[0024] Preferably, the fully quantitative treatment system further comprises an anaerobic reaction unit, the anaerobic reaction unit is connected to the membrane treatment unit, and the anaerobic reaction unit is connected to the submerged combustion evaporator via a biogas pipe.

[0025] The present invention also provides a fully quantitative treatment method for landfill leachate, the fully quantitative treatment method adopts the fully quantitative treatment system described above, and the fully quantitative treatment method comprises the following steps:

[0026] S1, using a membrane treatment unit to concentrate the landfill leachate to obtain a membrane concentrate;

[0027] S2, passing the obtained membrane concentrate into the primary reduction unit, and the membrane concentrate is treated with a low concentration ratio by the preheater, and the membrane concentrate treated by the preheater is sprayed back to the furnace through the spray back unit or flows to the secondary reduction unit;

[0028] S3, the MVR evaporator in the secondary reduction unit performs medium concentration rate treatment on the membrane concentrate, and the membrane concentrate treated by the MVR evaporator is sprayed back to the furnace through the spray back unit or flows to the tertiary reduction unit;

[0029] S4. The submerged combustion evaporator in the three-stage reduction unit treats the membrane concentrate at a high concentration rate, and the membrane concentrate treated by the submerged combustion evaporator is sprayed back to the furnace through the spray back unit.

[0030] Preferably, the membrane concentrate treated with a low concentration ratio adopts a high back-spraying volume, the membrane concentrate treated with a medium concentration ratio adopts a medium back-spraying volume, and the membrane concentrate treated with a high concentration ratio adopts a low back-spraying volume.

[0031] The invention provides a fully quantitative treatment system and method for landfill leachate, which has the following beneficial effects:

[0032] (1) The present invention is provided with a total of three-stage reduction units, and uses a preheater, an MVR evaporation unit and an immersion combustion evaporator to perform graded evaporation treatment on the membrane concentrate. The concentration degree of the membrane concentrate obtained after graded evaporation is different. The back-spraying amount of the membrane concentrate is controlled according to the different concentration degrees, so as to ensure that the membrane concentrate adapts to the combustion conditions of the furnace during back-spraying, achieve the reduction of the membrane concentrate, and achieve controllable adjustment of the back-spraying amount, thereby ensuring that the boiler maintains the best operating state while achieving full quantification and harmless treatment of the landfill leachate.

[0033] (2) The system of the present invention obtains low-temperature waste heat resources from the chimney of the waste incineration plant, and treats waste with waste based on the waste heat and waste gas resources generated by the domestic waste incineration plant, thus having the advantages of low operating cost and low carbon greenness.

[0034] (3) In the system of the present invention, the preheater, MVR evaporation unit, submerged combustion evaporator and organic Rankine cycle are coupled with each other and have a certain degree of freedom, which can maximize the efficient utilization of resources. The steam-electric dual-drive compressor realizes the allocation of the system energy path and expands the system membrane concentrate spraying capacity. The system can fully treat the leachate and generate electricity, thereby improving the system efficiency output. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of the structure of a fully quantitative treatment system for landfill leachate provided by an embodiment of the present invention;

[0036] Main figure markings: 1-preheater; 2-submerged combustion evaporator; 3-MVR evaporator; 4-steam-electric dual-drive compressor; 5-turbine; 6-regenerator; 7-condenser; 8-circulation pump; 9-evaporator; 10-boosting pump; 11-cooler; 12-induced draft fan; 13-synchronous motor; 14-boosting fan; 101-first valve; 102-seventh valve; 103-second valve; 104-tenth valve; 105-third valve; 106-fifth valve; 107-ninth valve; 108-eighth valve; 109-fourth valve; 110-sixth valve. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "top", "bottom", "top surface", "bottom surface", "inside", "outside", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0039] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If the terms "first", "second", "third" are described, they are only used for the purpose of description and distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The following is an explanation of the embodiments of the present invention based on its overall structure.

[0041] See also Figure 1 A fully quantitative treatment system for landfill leachate, the fully quantitative treatment system comprising: a membrane treatment unit, a primary reduction unit, a secondary reduction unit, a tertiary reduction unit, a back-spray unit and an organic Rankine cycle unit.

[0042] See also Figure 1 The membrane treatment unit is used to concentrate the landfill leachate to obtain a membrane concentrate from the landfill leachate. The primary reduction unit includes a preheater 1 and a booster fan 14 connected to the preheater 1, a flue pipe is connected to the booster fan 14, and the preheater 1 is connected to the membrane treatment unit. The secondary reduction unit includes an MVR evaporator 3 and a steam-electric dual-drive compressor 4 connected to the MVR evaporator 3, and the MVR evaporator 3 is connected to the preheater 1. The tertiary reduction unit includes an immersed combustion evaporator 2, and the immersed combustion evaporator 2 is connected to the MVR evaporator 3. The backspray unit includes a booster pump 10, an induced draft fan 12 and a cooler 11, the cooler 11 is connected to the induced draft fan 12, the booster pump 10 is connected to the preheater 1, the MVR evaporator 3 and the immersed combustion evaporator 2, and the cooler 11 is connected to the preheater 1, the MVR evaporator 3 and the immersed combustion evaporator 2. The organic Rankine cycle unit is connected to the steam-electric dual-drive compressor 4 to provide power to the steam-electric dual-drive compressor 4 .

[0043] The flue pipe is connected to a chimney in a waste incineration plant, the chimney provides flue gas to the preheater 1 through the flue pipe, and the organic Rankine cycle unit obtains heat from the flue pipe.

[0044] Specifically, the flue pipe is connected to a first valve 101 , and the first valve 101 is used to open the flue pipe so that the flue gas in the flue pipe can flow into the preheater 1 .

[0045] See also Figure 1Specifically, the organic Rankine cycle unit includes an evaporator 9, a condenser 7, a regenerator 6, a circulating pump 8, a turbine 5 and a synchronous motor 13. The synchronous motor 13 is connected to the turbine 5, the turbine 5 is connected to the steam-electric dual-drive compressor 4, the evaporator 9 is connected to the regenerator 6, the regenerator 6 is connected to the condenser 7, the condenser 7 and the regenerator 6 are both connected to the circulating pump 8, the condenser 7 and the regenerator 6 are both connected to the turbine 5; the evaporator 9 is connected to the flue pipe.

[0046] See also Figure 1 In the fully quantitative treatment system of garbage leachate provided in the above embodiment, a smoke outlet is provided on the chimney of the garbage incineration plant, and the flue pipe is connected to the smoke outlet. The flue gas incinerated in the garbage incineration plant enters the preheater 1 through the booster fan 14. In the preheater 1, the flue gas and the membrane concentrate are directly contacted for heat exchange. The membrane concentrate is heated and evaporated. The evaporated liquid formed by evaporation, that is, the membrane concentrate with a low concentration ratio, is sprayed back into the furnace through the booster pump 10 or enters the MVR evaporator 3. The flue gas after heat exchange in the preheater 1 and the non-condensable gas generated during the evaporation process of the preheater 1 enter the cooler 11, and after being exchanged for water heat, they are sent to the furnace through the induced draft fan 12.

[0047] The evaporated liquid formed by the preheater 1 enters the MVR evaporator 3 after the temperature stabilizes. The MVR evaporator 3 evaporates the evaporated liquid for the second time. The evaporated liquid obtained by the MVR evaporator 3 can be used for crystallization and salt extraction or sprayed back into the furnace through the booster pump 10, or enters the submerged combustion evaporator 2. The water produced by the MVR evaporator 3 can enter the membrane treatment unit for filtration, and the non-condensable gas produced enters the cooler 11. After being exchanged for water heat, it is sent to the furnace through the induced draft fan 12. In the process of evaporating the membrane concentrate in the MVR evaporator 3, the organic medium in the evaporator 9 on the flue absorbs heat and enters the turbine 5 to expand and work, driving the steam-electric dual-drive compressor 4 to rotate at high speed to compress the primary steam, making full use of the latent heat of the primary steam. The organic medium after work enters the condenser 7 after passing through the regenerator 6, and then realizes the work cycle through the circulating pump 8.

[0048] The evaporating liquid after evaporation and concentration in the MVR evaporator 3 enters the submerged combustion evaporator 2. The submerged combustion evaporator 2 uses biogas and air for combustion. The high-temperature flue gas generated by the combustion directly contacts the evaporating liquid for heat exchange. During the evaporation process, the flue gas contains a large amount of non-condensable gas, which leads to a decrease in the partial pressure of water vapor and a decrease in the stable evaporation temperature of the liquid phase, thereby achieving the effect of reduced-pressure evaporation under normal pressure conditions. The flue gas and non-condensable gas generated by the submerged combustion evaporator 2 are heat exchanged in the cooler 11 and then sent to the furnace through the induced draft fan 12. The salt mud generated by evaporation and concentration in the submerged combustion evaporator 2 is sent to the grate for incineration, and the evaporating liquid after evaporation and concentration is sprayed back to the furnace for incineration through the booster pump 10; the condensed water generated by the cooling of the flue gas or non-condensable gas in the cooler 11 enters the membrane treatment unit for filtration.

[0049] The fully quantitative treatment system for landfill leachate provided in the above embodiment utilizes a preheater, an MVR evaporator and an immersion combustion evaporator to realize step-by-step evaporation of membrane concentrate. The concentration ratio of the membrane concentrate after each stage of evaporation increases, and the corresponding back-spray volume also decreases step by step accordingly, thereby achieving a reduction in the amount of landfill leachate and getting rid of the pain point that the back-spray volume cannot be adjusted when the existing membrane concentrate is incinerated by back-spray.

[0050] See also Figure 1 In a preferred embodiment, the membrane treatment unit includes an ultrafiltration membrane (UF), a nanofiltration membrane (NF) and a reverse osmosis membrane, the reverse osmosis membrane is a disc tube reverse osmosis (DTRO), the garbage leachate is sequentially concentrated through the ultrafiltration membrane, the nanofiltration membrane and the reverse osmosis membrane, and the nanofiltration membrane and the reverse osmosis membrane are respectively connected to the water system. The water outlet ends of the nanofiltration membrane and the reverse osmosis membrane are respectively connected to the water system, the membrane concentrate concentrated by the nanofiltration membrane and the reverse osmosis membrane can enter the preheater 1, and the water obtained by the nanofiltration membrane and the reverse osmosis membrane can enter the water system.

[0051] See also Figure 1 As a preferred embodiment, the water inlet of the cooler 11 is connected to the water outlet of the reverse osmosis membrane, the water outlet of the cooler 11 is connected to the preheater 1, a seventh valve 102 is connected between the water outlet of the cooler 11 and the preheater 1, and the water outlet of the cooler 11 is also connected to the water inlet of the nanofiltration membrane.

[0052] The membrane concentrate obtained through the reverse osmosis membrane can enter the cooler 11 through the water inlet of the cooler 11, and the flue gas and non-condensable gas flowing out of the preheater 1 can exchange heat with the membrane concentrate in the cooler 11. At the same time, the membrane concentrate after heat exchange enters the preheater 1 through the seventh valve 102 to evaporate, so as to achieve the purpose of efficient use of system heat. The water produced by the cooler 11 can enter the membrane treatment unit, and then be discharged into the water system after being treated by the nanofiltration membrane.

[0053] See also Figure 1 As a preferred embodiment, an eighth valve 108 is connected between the MVR evaporator 3 and the cooler 11; an outlet pipe is connected to the MVR evaporator 3, the outlet pipe is connected to the water inlet end of the nanofiltration membrane, and a ninth valve 107 is connected to the outlet pipe.

[0054] The non-condensable gas generated by the MVR evaporator 3 enters the cooler 11, and the non-condensable gas generated by the MVR evaporator 3 can enter the cooler 11 through the eighth valve 108. The water generated by the MVR evaporator 3 can enter the membrane treatment unit through the ninth valve 107, and then be discharged into the water system after being treated by the nanofiltration membrane.

[0055] See also Figure 1 In a preferred embodiment, a first back-spray pipe is connected between the preheater 1 and the booster pump 10, and a second valve 103, a third valve 105 and a fourth valve 109 are connected to the first back-spray pipe; a second back-spray pipe is connected between the preheater 1 and the MVR evaporator 3, and a fifth valve 106 is connected to the second back-spray pipe; a third back-spray pipe is connected between the MVR evaporator 3 and the submerged combustion evaporator 2, and a sixth valve 110 is connected to the three back-spray pipes.

[0056] Specifically, in order to make the entire system more convenient to operate with higher freedom and save costs, the circulation pipes and valves of the evaporating liquid between the preheater 1, the MVR evaporator 3 and the submerged combustion evaporator 2 can be designed more specifically according to the flow direction of the evaporating liquid between the three.

[0057] See also Figure 1 For example, in the present invention, the second valve 103 and the fifth valve 106 are used for the circulation of evaporative liquid between the preheater 1 and the MVR evaporator 3; the second valve 103, the third valve 105, and the fourth valve 109 are used for the evaporative liquid in the preheater 1 to flow directly to the furnace; the sixth valve 110 is used for the circulation of evaporative liquid between the MVR evaporator 3 and the submerged combustion evaporator 2; the fourth valve 109 is used for the evaporative liquid in the MVR evaporator 3 to flow directly to the furnace; the seventh valve 102 is used for the membrane concentrate in the cooler 11 to flow to the preheater 1, and the tenth valve 104 is used as a bypass valve for the membrane concentrate to flow out of the cooler 11; the eighth valve 108 is used for the non-condensable gas in the MVR evaporator 3 to flow to the cooler 11; and the ninth valve 107 is used for the water generated in the MVR evaporator 3 to flow to the membrane treatment unit.

[0058] See also Figure 1In a preferred embodiment, the fully quantitative treatment system further comprises an anaerobic reaction unit, the anaerobic reaction unit is connected to the membrane treatment unit, and the anaerobic reaction unit is connected to the submerged combustion evaporator 2 through a biogas pipe.

[0059] Among them, when the landfill leachate is treated by anaerobic nitrification reaction, it has the advantages of energy recovery, reduction of organic matter load and reduction of sludge production. The anaerobic nitrification reaction of the landfill leachate will produce biogas, and the submerged combustion evaporator 2 directly uses the biogas produced by the anaerobic nitrification reaction of the landfill leachate as fuel.

[0060] Combine the following Figure 1 How the system provided by the present invention performs the reduced-volume spraying of the membrane concentrate is described, and the specific description is as follows:

[0061] The leachate is first processed through UF, NF and DTRO in the membrane treatment units in sequence to obtain membrane concentrate, which then enters the cooler 11. At the same time, when the system is running, the first valve 101 is opened, the booster fan 14 is started, the flue gas in the flue is sent into the preheater 1 through the smoke outlet, the seventh valve 102 is opened, and the membrane concentrate in the cooler 11 enters the preheater 1.

[0062] In the preheater 1, the flue gas and the membrane concentrate are in direct contact for heat exchange, the membrane concentrate is heated and partially evaporated, and after the temperature of the evaporated liquid is stabilized, the second valve 103 and the fifth valve 106 are opened, and the evaporated liquid enters the MVR evaporator 3 from the preheater 1. The flue gas after heat exchange in the preheater 1 and the non-condensable gas generated during the evaporation process enter the cooler 11, and after exchanging water heat with the membrane concentrate, they are sent to the furnace through the induced draft fan 12. The preheated evaporated liquid enters the MVR evaporator 3 for low-rate concentration (concentration rate n<10), at which time the organic medium in the main flue evaporator 9 absorbs heat and enters the turbine 5 to expand and work, driving the steam-electric dual-drive compressor 4 to rotate at high speed to compress the primary steam, making full use of the latent heat of the primary steam, and the organic medium after work enters the condenser 7 after passing through the regenerator 6, and then realizes the work cycle through the circulating pump 8.

[0063] On the MVR evaporator 3, the ninth valve 107 is opened, and the evaporated water in the MVR evaporator 3 enters the NF water inlet, while the non-condensable gas enters the cooler 11 through the eighth valve 108 to exchange heat with the membrane concentrate and is then sent to the furnace through the induced draft fan 12. The evaporated liquid concentrated by the MVR evaporator 3 can be used for crystallization and salt extraction or enter the submerged combustion evaporator 2 through the sixth valve 110 for high-ratio (concentration ratio n≥10) concentration.

[0064] The biogas produced by the anaerobic nitrification reaction of the leachate is mixed with air and enters the submerged combustion evaporator 2. The high-temperature flue gas produced by the combustion directly contacts the evaporating liquid for heat exchange. During the evaporation process, the flue gas contains a large amount of non-condensable gas, which leads to a decrease in the partial pressure of water vapor and a decrease in the stable evaporation temperature of the liquid phase, thereby achieving the effect of reduced-pressure evaporation under normal pressure conditions. The flue gas and non-condensable gas are heat-exchanged with the membrane concentrated liquid through the cooler 11 and then sent to the furnace through the induced draft fan 12. The salt mud produced by evaporation and concentration is sent to the grate for incineration, and the evaporating liquid after evaporation and concentration is sprayed back to the furnace for incineration through the booster pump 10; the condensed water produced by the cooling of the flue gas or non-condensable gas in the cooler 11 enters the water inlet end of the NF.

[0065] The embodiment of the present invention further provides a fully quantitative treatment method for landfill leachate, the fully quantitative treatment method adopts the fully quantitative treatment system described above, and the treatment method comprises the following steps:

[0066] S1. Using a membrane treatment unit to concentrate the landfill leachate to obtain a membrane concentrate.

[0067] S2. The obtained membrane concentrate is introduced into the primary reduction unit, and the membrane concentrate is treated with a low concentration ratio by the preheater. The membrane concentrate treated by the preheater is sprayed back into the furnace through the spray back unit or flows into the secondary reduction unit.

[0068] S3. The MVR evaporator in the secondary reduction unit performs medium concentration ratio treatment on the membrane concentrate. The membrane concentrate treated by the MVR evaporator is sprayed back to the furnace through the spray back unit or flows to the tertiary reduction unit.

[0069] S4. The submerged combustion evaporator in the three-stage reduction unit treats the membrane concentrate at a high concentration rate, and the membrane concentrate treated by the submerged combustion evaporator is sprayed back to the furnace through the spray back unit.

[0070] In a preferred embodiment, the membrane concentrate treated with a low concentration ratio adopts a high back-spraying amount, the membrane concentrate treated with a medium concentration ratio adopts a medium back-spraying amount, and the membrane concentrate treated with a high concentration ratio adopts a low back-spraying amount.

[0071] In summary, based on the system provided by the present invention and the proposed method for full-scale treatment, the treatment of the membrane concentrate of the landfill leachate in the present invention has the following modes:

[0072] The first type: low concentration ratio + high back spray volume

[0073] At this time, after the membrane concentrate produced by the membrane treatment unit is heated by the preheater 1, the second valve 103, the third valve 105 and the fourth valve 109 are opened, and the preheated concentrate is directly sprayed back to the furnace, and the flue gas and non-condensable gas produced during the evaporation process enter the cooler 11, and after heat exchange with the membrane concentrate water, it is sent to the furnace through the induced draft fan 12; the organic Rankine cycle device can be shut down, or operate normally and drive the synchronous motor 13 to generate electricity through the turbine 5, and the generated electricity can be used for the power consumption of the municipal solid waste incineration plant.

[0074] The second type: medium concentration ratio + medium back spray volume

[0075] At this time, after the membrane concentrate produced by the membrane treatment unit is heated by the preheater 1, the second valve 103 and the fifth valve 106 are opened, and the evaporated liquid enters the MVR evaporator 3 for low-rate evaporation and concentration. After that, the fourth valve 109 is opened to spray the evaporated concentrate back to the furnace, and the flue gas in the preheater 1 and the MVR evaporator 3 and the non-condensable gas produced during the evaporation process enter the cooler 11, and after heat exchange with the membrane concentrate, they are sent into the furnace through the induced draft fan 12; the organic Rankine cycle provides power for the compressor, and when the output power of the turbine 5 is greater than the power of the steam-electric dual-drive compressor 4, the synchronous motor 13 is coupled to participate in power generation; when the output power of the turbine 5 is less than the steam-electric dual-drive compressor 4, the synchronous motor 13 and the turbine 5 jointly drive the steam-electric dual-drive compressor 4 to maintain the evaporation processing capacity.

[0076] The third type: high concentration ratio + low back spray volume

[0077] At this time, the membrane concentrate produced by the membrane treatment unit is heated by the preheater 1 and enters the MVR evaporator 3 and the submerged combustion evaporator 2 in sequence, and then sprayed back to the furnace. The flue gas in the preheater 1, the submerged combustion evaporator 2 and the MVR evaporator 3 and the non-condensable gas produced during the evaporation process enter the cooler 11, and after heat exchange with the membrane concentrate, it is sent into the furnace through the induced draft fan 12; the organic Rankine cycle provides power for the steam-electric dual-drive compressor 4 in the MVR evaporation system. When the output power of the turbine 5 is greater than that of the steam-electric dual-drive compressor 4, the synchronous motor 13 is coupled to participate in power generation; anaerobic biogas is used as fuel for the submerged combustion evaporator to provide energy for high-rate concentration.

[0078] The fourth type: power generation mode

[0079] At this time, the preheater 1, the MVR evaporator 3 and the submerged combustion evaporator 2 are not working, and the organic Rankine cycle drives the synchronous motor 13 through the turbine 5 to enter a pure power generation mode.

[0080] In summary, the present invention provides a fully quantitative treatment system and method for landfill leachate, which utilizes the flue gas from the tail flue of the domestic waste incineration plant to exchange heat with the preheater and evaporator, realizes low-rate concentration of the concentrated liquid through the MVR evaporator, and then uses anaerobic biogas as fuel to realize high-rate concentration of the concentrated liquid through the submerged combustion evaporator, and the evaporated liquid and non-condensable gas after evaporation and concentration are sprayed back to the furnace. The system is based on the waste heat and waste gas resources of the domestic waste incineration plant, and "treating waste with waste" has a lower operating cost. Through the step-by-step reduction treatment of the membrane concentrated liquid, it not only realizes the controllable adjustment of the spray back volume to ensure the optimal operation state of the boiler, but also provides conditions for the full quantification and resource utilization of the membrane concentrated liquid.

[0081] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A fully quantitative treatment system for landfill leachate, characterized in that: The full quantization processing system comprises: A membrane treatment unit, wherein the membrane treatment unit is used to concentrate the landfill leachate to obtain a membrane concentrate from the landfill leachate; A primary reduction unit, the primary reduction unit comprising a preheater and a booster fan connected to the preheater, the booster fan being connected to a flue pipe, and the preheater being connected to the membrane treatment unit; A secondary reduction unit, the secondary reduction unit comprising an MVR evaporator and a steam-electric dual-drive compressor connected to the MVR evaporator, the MVR evaporator being connected to the preheater; A three-stage reduction unit, the three-stage reduction unit includes a submerged combustion evaporator, the submerged combustion evaporator is connected to the MVR evaporator; A back-spray unit, the back-spray unit comprising a booster pump, an induced draft fan and a cooler, the cooler being connected to the induced draft fan, the booster pump being connected to the preheater, the MVR evaporator and the submerged combustion evaporator, and the cooler being connected to the preheater, the MVR evaporator and the submerged combustion evaporator; An organic Rankine cycle unit, the organic Rankine cycle unit is connected to the steam-electric dual-drive compressor to provide power to the steam-electric dual-drive compressor; The flue pipe is connected to a chimney in a waste incineration plant, the chimney provides flue gas to the preheater through the flue pipe, and the organic Rankine cycle unit obtains heat from the flue pipe.

2. A fully quantitative treatment system for landfill leachate according to claim 1, characterized in that: The membrane treatment unit comprises an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane. The garbage leachate is concentrated by passing through the ultrafiltration membrane, the nanofiltration membrane and the reverse osmosis membrane in sequence. The nanofiltration membrane and the reverse osmosis membrane are respectively connected to a water system.

3. A fully quantitative treatment system for landfill leachate according to claim 1, characterized in that: The organic Rankine cycle unit includes an evaporator, a condenser, a regenerator, a circulation pump, a turbine and a synchronous motor. The synchronous motor is connected to the turbine, the turbine is connected to the steam-electric dual-drive compressor, the evaporator is connected to the regenerator, the regenerator is connected to the condenser, the condenser and the regenerator are both connected to the circulation pump, the condenser and the regenerator are both connected to the turbine; the evaporator is connected to the flue pipe.

4. The fully quantitative treatment system for landfill leachate according to claim 1 is characterized in that: The flue pipe is connected with a first valve.

5. The fully quantitative treatment system for landfill leachate according to claim 1 is characterized in that: A first back-spray pipeline is connected between the preheater and the booster pump, and a second valve, a third valve and a fourth valve are connected to the first back-spray pipeline; A second back-spray pipeline is connected between the preheater and the MVR evaporator, and a fifth valve is connected to the second back-spray pipeline; A third return spray pipeline is connected between the MVR evaporator and the submerged combustion evaporator, and a sixth valve is connected to the third return spray pipeline.

6. The fully quantitative treatment system for landfill leachate according to claim 2 is characterized in that: The water inlet of the cooler is connected to the water outlet of the reverse osmosis membrane, the water outlet of the cooler is connected to the preheater, a seventh valve is connected between the water outlet of the cooler and the preheater, and the water outlet of the cooler is also connected to the water inlet of the nanofiltration membrane.

7. The fully quantitative treatment system for landfill leachate according to claim 2 is characterized in that: An eighth valve is connected between the MVR evaporator and the cooler; a water outlet pipe is connected to the MVR evaporator, the water outlet pipe is connected to the water inlet end of the nanofiltration membrane, and a ninth valve is connected to the water outlet pipe.

8. The fully quantitative treatment system for landfill leachate according to claim 1 is characterized in that: The fully quantitative treatment system further comprises an anaerobic reaction unit, the anaerobic reaction unit is connected to the membrane treatment unit, and the anaerobic reaction unit is connected to the submerged combustion evaporator through a biogas pipe.

9. A fully quantitative treatment method for landfill leachate, characterized in that: The full quantization processing method adopts the full quantization processing system according to any one of claims 1 to 8 above, and the full quantization processing method comprises the following steps: S1, using a membrane treatment unit to concentrate the landfill leachate to obtain a membrane concentrate; S2, passing the obtained membrane concentrate into the primary reduction unit, and the membrane concentrate is treated with a low concentration ratio by the preheater, and the membrane concentrate treated by the preheater is sprayed back to the furnace through the spray back unit or flows to the secondary reduction unit; S3, the MVR evaporator in the secondary reduction unit performs medium concentration treatment on the membrane concentrate, and the membrane concentrate treated by the MVR evaporator is sprayed back to the furnace through the spray back unit or flows to the tertiary reduction unit; S4. The submerged combustion evaporator in the three-stage reduction unit treats the membrane concentrate at a high concentration rate, and the membrane concentrate treated by the submerged combustion evaporator is sprayed back to the furnace through the spray back unit.

10. A fully quantitative treatment method for landfill leachate according to claim 9, characterized in that: The membrane concentrate treated with the low concentration ratio adopts a high back-spraying amount, the membrane concentrate treated with the medium concentration ratio adopts a medium back-spraying amount, and the membrane concentrate treated with the high concentration ratio adopts a low back-spraying amount.

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