A method for drying chicken manure

Abstract

The present application relates to livestock manure resource processing technical field, specifically to a kind of chicken manure drying treatment method, the present application is through the construction "dry chicken manure returns burning self-supply heat-three stage gradient heat exchange-heat cascade reuse", completely get rid of the dependence on external fossil energy, substantially reduce operating energy consumption and operating cost;Through "Venturi condensation washing-three stage physical purification-wet desulphurization-SCR denitration-biological deodorization" multistage cascade purification combined operation, realize tail gas ultra-clean emission;Through ash back mixing significantly improve the total nutrient content of organic fertilizer, and realize full-process closed negative pressure operation, ensure that no organization zero dispersion of foul-smelling gas, the present application effectively solves the comprehensive technical problems of high energy consumption, high pollution, resource waste and uneven drying in chicken manure drying treatment, realizes the high unification of waste reduction, harmlessness and resource, has wide application prospect.

Description

Technical Field

[0001] This invention relates to the technical field of resource utilization treatment of livestock and poultry manure, and in particular to a method for drying chicken manure. Background Technology

[0002] With the rapid development of my country's poultry farming industry towards large-scale and intensive operations, especially the continuous increase in the number of broiler and layer chickens, the annual output of its byproduct—fresh chicken manure—has reached tens of millions of tons. Fresh chicken manure typically has a moisture content as high as 60%-80% and contains a large amount of undigested protein, fat, fiber, and nutrients such as nitrogen and phosphorus. If not properly disposed of, chicken manure will rapidly ferment and rot during the piling process, breeding mosquitoes, flies, and pathogens, and producing large amounts of ammonia, hydrogen sulfide, and other foul-smelling gases, posing a serious threat to the air quality, soil environment, and water safety around the farms. At the same time, as a biomass resource rich in organic matter and nitrogen, phosphorus, and potassium, directly discarding chicken manure also results in a huge waste of resources.

[0003] Therefore, reducing, rendering harmless, and recycling chicken manure is a key issue that urgently needs to be addressed for the green development of the livestock industry.

[0004] Existing technologies for the resource utilization of chicken manure mainly include aerobic composting, anaerobic fermentation to produce biogas, and direct drying for fertilizer production. While aerobic composting and anaerobic fermentation can achieve partial resource conversion, they generally suffer from problems such as long fermentation cycles, large land areas required, significant susceptibility to climate influences, and difficulty in effectively controlling odorous gases, failing to meet the continuous, daily production and disposal needs of large-scale farms. Direct drying for fertilizer production, due to its rapid processing speed and significant volume reduction effect, has become one of the mainstream technologies for large-scale chicken manure treatment.

[0005] However, existing chicken manure drying equipment mostly uses coal, natural gas, or electricity as external heat sources. This heating mode, which relies on external energy, has many drawbacks: First, the operating energy consumption cost is extremely high, resulting in poor economic efficiency, especially when energy prices fluctuate, placing a heavy burden on farm operations; second, the combustion of fossil fuels such as coal produces large amounts of sulfur dioxide, nitrogen oxides, and dust, which can easily cause secondary air pollution if not equipped with expensive desulfurization, denitrification, and dust removal equipment; third, the drying system design is crude, with large fluctuations in drying temperature, which can easily lead to uneven drying of materials and affect the quality stability of the final organic fertilizer product; fourth, the entire process lacks an energy recycling design, and the direct emission of high-temperature exhaust gas not only wastes waste heat resources but also increases environmental thermal pollution.

[0006] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a method for drying chicken manure. Summary of the Invention

[0007] In view of this, the purpose of this invention is to propose a method for drying chicken manure, so as to solve the problems of high energy consumption, high pollution, low resource utilization and uneven drying in the prior art.

[0008] To achieve the above objectives, the present invention provides a method for drying chicken manure.

[0009] A method for drying chicken manure, the specific steps of which are as follows: Step S1: In a sealed state, add fresh chicken manure into the receiving chamber, control the relative pressure of the receiving chamber to -30Pa to -80Pa, place it on a vibrating screen with a screen mesh size of 8-15mm, place it in a mixer and disperser, rotate at 40-80rpm, and stir for 5-15min. After stirring is completed, dispersed chicken manure is obtained. Step S2: Add the dispersed chicken manure into the drying drum. The drum rotates at 3-8 rpm. For the first batch, start the auxiliary heat source and heat the air to 95-105℃. Hold for 25-45 minutes and dry until the output moisture content is ≤15% to obtain dry chicken manure. Step S3: Add the dried chicken manure to the pneumatic three-way distributor, preset the splitting ratio, and transport the first part of the chicken manure, which accounts for 30%-40% of the total mass of dried chicken manure, to the fuel storage bin of the drying drum, and transport the remaining 60%-70% of the second part of the chicken manure to the finished product bin as raw material for organic fertilizer biomass. Step S4: In subsequent batch processing, repeat step S1 and the operation of feeding loose chicken manure into the drying drum, ignite the dried chicken manure in the fuel storage bin, use staged air distribution for combustion, with an excess air coefficient of 1.15-1.30, a combustion temperature of 850-1050℃, and a combustion chamber pressure of -50Pa to -150Pa, to obtain high-temperature flue gas, ash and exhaust gas. Step S5: High-temperature flue gas is introduced into a three-stage gradient heat exchange system, and clean air heat exchange medium is introduced. The flue gas is cooled to 120-150℃, and the clean air is heated to 80-120℃, resulting in low-temperature flue gas and clean hot air. Step S6: The low-temperature flue gas and exhaust gas are passed into the first-stage Venturi, condensed and washed, and cooled to 60-80℃. They are then sequentially processed by a pulse dust collector, chemically removed by a wet scrubbing absorption tower, denitrified by a low-temperature SCR reactor, and biologically deodorized by a bio-trickling filter deodorization tower. After the treatment is completed, clean exhaust gas is obtained. Step S7: Cool the ash to 50-60℃ and send it into the finished product silo in step S3 through a pneumatic conveying device to mix it with the organic fertilizer biomass raw materials to obtain phosphorus and potassium rich organic fertilizer.

[0010] After the high-temperature flue gas generated by combustion in step S4 provides continuous hot air for the drying operation in step S2 through the three-stage gradient heat exchange system in subsequent step S5, the auxiliary heat source is shut off, and the system enters the normal operation stage of self-heating by burning dried chicken manure. Preferably, the preset splitting ratio R, which accounts for 30%-40% of the total mass of dried chicken manure in step S3, has a base setting value R0 of 35%. The preset split ratio is dynamically feedforward corrected according to the initial moisture content ω1 of the fresh chicken manure in step S1, that is, the moisture content of the loose chicken manure before entering the drying drum, according to the following rules: When ω1≥75%, R=37%-40%; When 65%≤ω1<75%, R=33%-37%; When ω1 < 65%, R = 30% - 33%; The specific formula for calculating the value of R is as follows: ω1 is substituted as a percentage value, and the calculation result is limited to a closed interval of 30%-40%.

[0011] The correction coefficient of 0.005 is determined based on the linear regression relationship between the moisture content of chicken manure and the calorific value of dry matter. For every 1 percentage point increase in the moisture content of chicken manure, its calorific value of dry matter decreases by about 0.005 kcal / kg. Accordingly, the proportion of reburned fuel needs to be increased to maintain the thermal balance of the system. This coefficient is obtained by fitting the thermogravimetric analysis experiment of chicken manure fuel with the system thermal balance calculation.

[0012] Preferably, the specific method of staged air distribution combustion in step S4 is: a combined supply of primary air and secondary air; The volume ratio of the primary air to the secondary air is 55-65:45-35; The primary air is introduced from the swirl plate at the bottom of the combustion chamber, carrying chicken manure fuel and rising in a vortex; The secondary air is injected tangentially from the circumferentially distributed air inlets in the center of the combustion chamber.

[0013] Preferably, the specific method of the three-stage gradient heat exchange in step S5 is as follows: the material of the first-stage heat exchanger is heat-resistant stainless steel 310S, which raises the temperature of the primary air to 200-250℃. The secondary heat exchanger is made of heat-resistant stainless steel 304, which raises the temperature of the secondary air to 150-180℃; The three-stage heat exchanger is made of galvanized carbon steel tubes and heats clean air to 80-120℃.

[0014] Preferably, the specific method of condensation washing in step S6 is as follows: low-temperature flue gas and tail gas are introduced into a Venturi condensation washing tower, and spray washing is performed using circulating cooling water at 20-25℃, with a spray liquid-to-gas ratio of 3-8 L / m³.3 The condensate is recovered and used as makeup water for the cooling tower.

[0015] Preferably, the recycling process of the pulse dust removal unit in step S6 specifically involves: passing the low-temperature flue gas and exhaust gas into a pulse dust collector for three-stage physical purification. In the first stage of gravity settling, the apparent flow velocity is 0.3-0.5 m / s, and coarse dust with a particle size > 50 μm settles. The second-stage PTFE membrane filter bag filtration section filters fine dust with a filtration velocity of 0.8-1.2 m / min and a particle size of 0.5-50 μm. The third-stage high-voltage pulsed electric field adsorption section operates at a voltage of 30-50kV, a pulse frequency of 40-80Hz, and an adsorption particle size of ≤0.5μm.

[0016] Preferably, the specific method for chemical deep removal using a wet scrubbing absorption tower, denitrification using a low-temperature SCR reactor, and biological deodorization using a bio-trickling filtration deodorization tower in step S6 is as follows: Low-temperature flue gas and tail gas after pulse dust removal are introduced into a scrubbing absorption tower for limestone-gypsum desulfurization. The gas is placed in a primary steam heat exchanger and heated to 180-220°C. It is then introduced into a low-temperature SCR reactor, where ammonia water (a reducing agent) and a vanadium-based low-temperature denitrification catalyst are added for denitrification. Finally, the gas is introduced into a bio-trickling filtration deodorization tower, which is filled with polyurethane bio-sponge packing material. The packing surface contains malodorous Pseudomonas aeruginosa and nitrifying bacteria, ensuring that the NH3 concentration in the outlet gas is ≤5 mg / m³. 3 H2S concentration ≤ 0.5 mg / m³ 3 .

[0017] Preferably, the receiving chamber in step S1 is a fully enclosed steel structure with a breathing valve and a negative pressure ventilation system at the top, and the extracted ammonia-containing air is introduced into the waste gas treatment system in step S6.

[0018] Preferably, the ash in step S7 contains ≥8% P2O5 and ≥12% K2O. The mass ratio of the ash to the organic fertilizer biomass raw material is 1:12-18.

[0019] Preferably, the fuel storage bin in step S4 is equipped with an insulation jacket and a material level sensor, and a variable frequency screw feeder is installed at the bottom of the bin. Dry hot air at 40-50°C, which has been preheated by a heat exchanger, is introduced into the bin for protection. The drying cylinder is an inclined rotating cylinder with a length-to-diameter ratio of 8-12 and an inclination angle of 3°-6°.

[0020] The beneficial effects of this invention are: This invention constructs an energy self-circulation system of "dried chicken manure reheating for self-heating - three-stage gradient heat exchange - waste heat cascade recovery". Part of the dried chicken manure is returned as fuel. The hot flue gas generated after high-temperature combustion with graded air distribution is converted into clean hot air through multi-stage heat exchange and circulated for material drying. This allows the system to completely get rid of dependence on external fossil energy during normal operation, greatly reducing the energy consumption and operating costs of drying treatment. At the same time, it realizes the on-site energy utilization of livestock waste, which has good economic benefits and resource recycling benefits.

[0021] This invention employs a multi-stage, cascaded purification process—"Venturi condensation washing - gravity settling - PTFE membrane filter bag filtration - high-voltage pulsed electric field adsorption - wet desulfurization and denitrification - bio-trickling filtration deodorization"—to uniformly collect and deeply treat drying exhaust gas and combustion flue gas. This efficiently removes particulate matter, sulfur oxides, nitrogen oxides, and odorous gases such as ammonia and hydrogen sulfide from the exhaust gas, ensuring clean and compliant emissions. Simultaneously, it recovers condensate and dust for resource utilization, balancing environmental and resource recovery benefits.

[0022] This invention involves cooling the high-temperature ash generated from burning chicken manure and then pneumatically transporting it back into the finished organic fertilizer. By utilizing the abundant phosphorus, potassium, and other plant nutrients in the ash, the organic fertilizer is nutrient-enhanced. This significantly increases the total nutrient content of the finished organic fertilizer without the need for additional chemical phosphorus and potassium fertilizers. At the same time, it supplements trace elements such as silicon, calcium, and magnesium, realizing an internal cycle of mineral elements from "fuel ash production - ash fertilization - fertilizer return to farmland," thereby improving the added value and market competitiveness of the product.

[0023] This invention, through the coordinated operation of a fully enclosed negative pressure system and a unified waste gas collection system, maintains a slight negative pressure state in all odor-generating stages, including the receiving chamber, combustion chamber, and drying cylinder. This ensures that odorous gases such as ammonia and hydrogen sulfide are completely and without any fugitive escape throughout the process, significantly improving the operating environment of farms and workshops. At the same time, the ammonia-containing waste gas is introduced into a subsequent treatment system for centralized purification, eliminating odor pollution at the source. It has good environmental friendliness and social benefits and is suitable for promotion and application in large-scale farms. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a simplified flowchart of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0027] The sources and properties of some of the raw materials used in this invention are as follows: The *Pseudomonas putida* used in this invention is *Pseudomonas putida* LPC24, which is disclosed in the invention patent with publication authorization number "CN101817593B" entitled "Application of an indole and skatole degrading strain LPC24", and accession number CCTCC NO: M209099. The nitrifying bacillus used in this invention is Nitrifying bacillus vesiculosus XY-01, which is disclosed in the invention patent with publication authorization number "CN104560821B" and title "A Nitrifying bacillus vesiculosus XY-01 and its culture method and application", and accession number CGMCC 10171.

[0028] All embodiments are based on Figure 1 ; Example 1: A method for drying chicken manure: S1: In a closed state, add fresh chicken manure into the receiving chamber, control the relative pressure of the receiving chamber to -30Pa, place it on a vibrating screen with a screen mesh size of 15mm, place it in a mixer and disperser, rotate at 40rpm, and stir for 15min. After stirring is completed, dispersed chicken manure is obtained. S2: Add the dispersed chicken manure into the drying drum with a length-to-diameter ratio of 8, an inclination angle of 6°, and a drum rotation speed of 3 rpm. For the first batch, start the auxiliary heat source to heat the air to 105°C, hold for 25 minutes, and dry until the output moisture content is ≤15% to obtain dry chicken manure. S3: Add the dried chicken manure to the pneumatic three-way distributor. In this embodiment, the initial moisture content ω1 of the fresh chicken manure is 80%. The distribution ratio is dynamically corrected according to the preset formula. The first portion of chicken manure, which accounts for 40% of the total mass of dried chicken manure, is transported to the fuel storage silo of the drying drum, while the remaining 60% of the second portion is transported to the finished product silo as raw material for organic fertilizer biomass. S4: In subsequent batch processing, repeat S1 and the operation of feeding loose chicken manure into the drying drum, ignite the dried chicken manure in the fuel storage bin, and adopt a staged air distribution combustion method with a combined supply of primary and secondary air. The primary air accounts for 55% of the total air volume and is fed in from the bottom swirl plate of the combustion chamber, carrying the chicken manure fuel and rising in a vortex. The secondary air accounts for 45% of the total air volume and is injected tangentially from the circumferentially distributed air outlets in the middle of the combustion chamber. The excess air coefficient is 1.15, the combustion temperature is 1050℃, and the combustion chamber pressure is -50Pa, resulting in high-temperature flue gas, ash and exhaust gas. S5: High-temperature flue gas is introduced into a three-stage gradient heat exchange system. The first-stage heat exchanger is made of heat-resistant stainless steel 310S, which raises the temperature of the primary air to 200℃. The second-stage heat exchanger is made of heat-resistant stainless steel 304, which raises the temperature of the secondary air to 180℃. The third-stage heat exchanger is made of carbon steel galvanized pipe, which cools the flue gas to 120℃ and heats the clean air to 80℃, resulting in low-temperature flue gas and clean hot air. S6: Low-temperature flue gas and exhaust gas are introduced into the first-stage venturi scrubber for condensation and washing, using 20°C circulating cooling water for spray washing, with a spray liquid-to-gas ratio of 8L / m³. 3 The temperature is lowered to 60℃, and the gas is then introduced into a pulse dust collector for three-stage physical purification. The first stage is a gravity settling section with an apparent velocity of 0.5 m / s, where coarse dust particles > 50 μm settle. The second stage is a PTFE-coated filter bag filtration section with a filtration velocity of 0.8 m / min, where fine dust particles 0.5-50 μm are filtered. The third stage is a high-voltage pulse electric field adsorption section with an operating voltage of 30 kV and a pulse frequency of 80 Hz, where adsorbed particles ≤ 0.5 μm are filtered. The gas is then introduced into a spray absorption tower for limestone-gypsum desulfurization. It is then placed in a primary steam heat exchanger and heated to 180℃ before being introduced into a low-temperature SCR reactor. Denitrification is achieved under the action of ammonia water as a reducing agent and a vanadium-based low-temperature denitrification catalyst. Finally, the gas is introduced into a biological trickling deodorization tower filled with polyurethane biological sponge packing material. The packing surface contains malodorous Pseudomonas and nitrifying bacteria, ensuring that the NH3 concentration in the outlet gas is ≤ 5 mg / m³. 3 H2S concentration ≤ 0.5 mg / m³ 3 Once the treatment is complete, the exhaust gas is clean. S7: Cool 1000g of ash to 50℃ and send it into the finished product silo in S3 through a pneumatic conveying device. Mix it with 12kg of organic fertilizer biomass raw material to obtain phosphorus- and potassium-rich organic fertilizer.

[0029] Example 2: A method for drying chicken manure: S1: In a closed state, add fresh chicken manure into the receiving chamber, control the relative pressure of the receiving chamber to -55Pa, place it on a vibrating screen with a screen mesh size of 12mm, place it in a mixer and disperser, rotate at 60rpm, and stir for 10min. After stirring is completed, dispersed chicken manure is obtained. S2: Add the dispersed chicken manure into the drying drum with a length-to-diameter ratio of 10, an inclination angle of 5°, and a drum rotation speed of 5 rpm. For the first batch, start the auxiliary heat source to heat the air to 100°C, hold for 35 minutes, and dry until the output moisture content is ≤15% to obtain dry chicken manure. S3: Add the dried chicken manure to the pneumatic three-way distributor. In this embodiment, the initial moisture content ω1 of the fresh chicken manure is 70%. The distribution ratio is dynamically corrected according to the preset formula. The first portion of chicken manure, which accounts for 35% of the total mass of dried chicken manure, is transported to the fuel storage bin of the drying drum, while the remaining 65% of the second portion is transported to the finished product bin as raw material for organic fertilizer biomass. S4: In subsequent batch processing, repeat S1 and the operation of feeding loose chicken manure into the drying drum, ignite the dried chicken manure in the fuel storage bin, and adopt a staged air distribution combustion method with a combined supply of primary and secondary air. The primary air accounts for 60% of the total air volume and is fed in from the bottom swirl plate of the combustion chamber, carrying the chicken manure fuel and rising in a vortex. The secondary air accounts for 40% of the total air volume and is injected tangentially from the circumferentially distributed air outlets in the middle of the combustion chamber. The excess air coefficient is 1.25, the combustion temperature is 950℃, and the combustion chamber pressure is -100Pa, resulting in high-temperature flue gas, ash and exhaust gas. S5: High-temperature flue gas is introduced into a three-stage gradient heat exchange system. The first-stage heat exchanger is made of heat-resistant stainless steel 310S, which raises the temperature of the primary air to 230℃. The second-stage heat exchanger is made of heat-resistant stainless steel 304, which raises the temperature of the secondary air to 165℃. The third-stage heat exchanger is made of carbon steel galvanized pipe, which cools the flue gas to 135℃ and heats the clean air to 100℃, resulting in low-temperature flue gas and clean hot air. S6: Low-temperature flue gas and exhaust gas are introduced into the first-stage venturi system for condensation and scrubbing, using 23°C circulating cooling water for spray scrubbing, with a spray liquid-to-gas ratio of 5L / m³. 3 The temperature is lowered to 70℃, and the gas is then introduced into a pulse dust collector for three-stage physical purification. The first stage is a gravity settling section with an apparent velocity of 0.4 m / s, where coarse dust particles > 50 μm settle. The second stage is a PTFE-coated filter bag filtration section with a filtration velocity of 1.0 m / min, where fine dust particles 0.5-50 μm are filtered. The third stage is a high-voltage pulse electric field adsorption section with an operating voltage of 40 kV and a pulse frequency of 60 Hz, adsorbing particles ≤ 0.5 μm. The gas is then introduced into a spray absorption tower for limestone-gypsum desulfurization. It is then placed in a primary steam heat exchanger and heated to 200℃ before being introduced into a low-temperature SCR reactor. Denitrification is achieved under the action of ammonia water as a reducing agent and a vanadium-based low-temperature denitrification catalyst. Finally, the gas is introduced into a biological trickling deodorization tower filled with polyurethane biological sponge packing material. The surface of the packing material contains malodorous Pseudomonas and nitrifying bacteria, ensuring that the NH3 concentration in the outlet gas is ≤ 5 mg / m³. 3 H2S concentration ≤ 0.5 mg / m³ 3 Once the treatment is complete, the exhaust gas is clean. S7: Cool 1000g of ash to 55℃ and send it into the finished product silo in S3 through a pneumatic conveying device. Mix it with 15kg of organic fertilizer biomass raw materials to obtain phosphorus- and potassium-rich organic fertilizer.

[0030] Example 3: A method for drying chicken manure: S1: In a closed state, add fresh chicken manure into the receiving chamber, control the relative pressure of the receiving chamber to -80Pa, place it on a vibrating screen with a screen mesh size of 8mm, place it in a mixer and disperser, rotate at 80rpm, mix for 5min, and after mixing is completed, dispersed chicken manure is obtained. S2: Add the dispersed chicken manure into the drying drum with a length-to-diameter ratio of 12, an inclination angle of 3°, and a drum rotation speed of 8 rpm. For the first batch, start the auxiliary heat source to heat the air to 95°C, hold for 45 minutes, and dry until the output moisture content is ≤15% to obtain dry chicken manure. S3: Add the dried chicken manure to the pneumatic three-way distributor. In this embodiment, the initial moisture content ω1 of the fresh chicken manure is 60%. The distribution ratio is dynamically corrected according to the preset formula. The first portion of chicken manure, which accounts for 30% of the total mass of dried chicken manure, is transported to the fuel storage silo of the drying drum, while the remaining 70% of the second portion is transported to the finished product silo as a biomass raw material for organic fertilizer. S4: In subsequent batch processing, repeat S1 and the operation of feeding loose chicken manure into the drying drum, ignite the dried chicken manure in the fuel storage bin, and adopt a staged air distribution combustion method with a combined supply of primary and secondary air. The primary air accounts for 65% of the total air volume and is fed in from the swirl plate at the bottom of the combustion chamber, carrying the chicken manure fuel and rising in a vortex. The secondary air accounts for 35% of the total air volume and is injected tangentially from the circumferentially distributed air outlets in the middle of the combustion chamber. The excess air coefficient is 1.30, the combustion temperature is 850℃, and the combustion chamber pressure is -150Pa, resulting in high-temperature flue gas, ash and exhaust gas. S5: High-temperature flue gas is introduced into a three-stage gradient heat exchange system. The first-stage heat exchanger is made of heat-resistant stainless steel 310S, which raises the temperature of the primary air to 250°C. The second-stage heat exchanger is made of heat-resistant stainless steel 304, which raises the temperature of the secondary air to 150°C. The third-stage heat exchanger is made of carbon steel galvanized pipe, which cools the flue gas to 150°C and heats the clean air to 120°C, resulting in low-temperature flue gas and clean hot air. S6: Low-temperature flue gas and exhaust gas are introduced into the first-stage venturi system for condensation and scrubbing, using 25°C circulating cooling water for spray scrubbing, with a spray liquid-to-gas ratio of 3L / m³. 3The temperature is lowered to 80℃, and the gas is then introduced into a pulse dust collector for three-stage physical purification. The first stage is a gravity settling section with an apparent flow velocity of 0.3 m / s, where coarse dust particles with a diameter > 50 μm settle. The second stage is a PTFE membrane filter bag filtration section with a filtration velocity of 1.2 m / min, where fine dust particles with a diameter of 0.5-50 μm are filtered. The third stage is a high-voltage pulse electric field adsorption section with an operating voltage of 30 kV and a pulse frequency of 80 Hz, where adsorbed particles with a diameter ≤ 0.5 μm are filtered. The gas is then introduced into a spray absorption tower for limestone-gypsum desulfurization. After being placed in a primary steam heat exchanger and heated to 220℃, the gas is introduced into a low-temperature SCR reactor, where denitrification is carried out under the action of a reducing agent (ammonia water) and a vanadium-based low-temperature denitrification catalyst. Finally, the gas is introduced into a biological trickling filter deodorization tower, which is filled with polyurethane biological sponge packing material to ensure that the NH3 concentration in the effluent is ≤ 5 mg / m³. 3 H2S concentration ≤ 0.5 mg / m³ 3 Once the treatment is complete, the exhaust gas is clean. S7: Cool 1000g of ash to 60℃ and send it into the finished product silo in S3 through a pneumatic conveying device. Mix it with 18kg of organic fertilizer biomass raw material to obtain phosphorus- and potassium-rich organic fertilizer.

[0031] Comparative Example 1: The difference between this comparative example and Example 1 is that a fixed split ratio is used in step S3, and dynamic feedforward correction is not performed based on the initial moisture content ω1 of the fresh chicken manure. That is, regardless of the value of ω1, the first part of the chicken manure, which accounts for 35% of the total mass of the dried chicken manure, is always transported to the fuel storage bin, and the remaining 65% of the second part of the chicken manure is transported to the finished product bin. The other steps and parameters are the same, and will not be repeated in this comparative example. Finally, phosphorus- and potassium-rich organic fertilizer and clean exhaust gas are obtained.

[0032] Comparative Example 2: The difference between this comparative example and Example 1 is that the three-stage gradient heat exchange system is omitted in step S5. Instead, a single-stage heat exchanger is used to directly exchange heat with clean air once to cool the high-temperature flue gas. That is, the high-temperature flue gas is cooled to 120°C after single-stage heat exchange, and the clean air is heated to 80°C. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, phosphorus- and potassium-rich organic fertilizer and clean exhaust gas are obtained.

[0033] Comparative Example 3: Compared with Example 1, the difference in this comparative example is that the third-stage high-voltage pulse electric field adsorption section of the pulse dust removal unit is omitted in step S6. That is, after the low-temperature flue gas and tail gas undergo two stages of physical purification through the gravity settling section and the PTFE membrane filter bag filtration section, they directly enter the spray absorption tower for subsequent treatment. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, phosphorus- and potassium-rich organic fertilizer and clean tail gas are obtained.

[0034] Comparative Example 4: The difference between this comparative example and Example 1 is that in step S7, the ash is not sent into the finished product silo through a pneumatic conveying device to be mixed with the organic fertilizer biomass raw materials. Instead, the ash is directly discharged as solid waste. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, organic fertilizer and clean exhaust gas are obtained.

[0035] Comparative Example 5: Compared with Example 1, the difference in this comparative example is that the low-temperature SCR reactor denitrification step is omitted in step S6. That is, the low-temperature flue gas and tail gas after pulse dust removal are directly fed into the biological trickling deodorization tower for biological deodorization after desulfurization by the spray absorption tower, without denitrification treatment. The remaining steps and parameters are the same, and will not be repeated in this comparative example. Finally, phosphorus- and potassium-rich organic fertilizer and clean tail gas are obtained.

[0036] Performance testing: System energy consumption test A Fluke 435-II three-phase power quality analyzer was used. A three-phase power quality analyzer was installed at the incoming line of the main distribution cabinet, and the total power consumption (kW·h) of Examples 1-3 and Comparative Examples 1-5 was recorded for 24 consecutive hours during the stable operation phase. A platinum resistance temperature sensor is installed at the straight section of the hot air inlet duct of the drying drum. The temperature sampling frequency is set to 10s / time, and the average temperature value is recorded every 10 minutes. Formulas for calculating the average temperature and its standard deviation:

[0037]

[0038] Where n=144, and Ti is the average temperature (°C) within the i-th 10-minute period. s is the total average temperature over 24 hours (°C), and s is the standard deviation (°C). Calculate the unit processing power consumption (e, kW·h / t):

[0039] Where E is the cumulative energy consumption in 24 hours, kW·h, and M is the total mass of fresh chicken manure processed, t; Table 1. System energy consumption test results of the examples and comparative examples

[0040] Exhaust emission testing: The Testo 350 portable flue gas analyzer was used in accordance with the HJ / T 397-2007 testing standard. Examples 1-3 and Comparative Examples 1-5 were run continuously for 72 hours. Data was collected at 24 hours after the start of the first test, at 48 hours after the start of the second test, and at 72 hours after the start of the third test. The effective sample collection method for each group was as follows: four instantaneous samples were collected every 15 minutes within one hour, and the arithmetic mean of the samples was taken as the effective concentration value of the group. Portable flue gas analyzer was used for online detection of particulate matter, SO2, and NO. X The emission concentration was determined by Nessler's reagent spectrophotometry; the H2S concentration was determined by methylene blue spectrophotometry.

[0041] Table 2. Exhaust emission test results of the examples and comparative examples

[0042] Organic fertilizer quality testing: Refer to the NY / T 525-2021 testing standard; Organic fertilizers from Examples 1-3 and Comparative Examples 1-5 were collected. 500g of each fertilizer was taken from the discharge port of the S7 finished product silo every 30 minutes. This was repeated 8 times to obtain 4kg of original sample. The sample was then reduced to 1kg using the quartering method, and 500g of the original sample was taken for testing. Determination of total nutrient mass fraction: Total nitrogen content determination: Take 0.5g of sample and place it in a digestion tube. Add concentrated sulfuric acid and a mixed catalyst, which is copper sulfate and potassium sulfate in a mass ratio of 1:10. Heat to 420℃. The solution is transparent blue-green. Cool and dilute to 100mL. Take 10mL of the diluted solution and distill it using an automated Kjeldahl nitrogen analyzer. Calculate the total nitrogen content (%) based on the amount of hydrochloric acid standard solution consumed. Total phosphorus content determination: Take 0.5g of sample, prepare the test solution using sulfuric acid-hydrogen peroxide digestion method, and make up to 100mL. Take 5.00mL of the test solution and add it to a 50mL volumetric flask. Add the colorimetric reagent vanadium molybdic acid, make up to the mark, mix well, and let stand for 15min. Measure the absorbance using a spectrophotometer at a wavelength of 440nm. Total potassium content test: Take the test solution for total phosphorus content test, measure it with a flame photometer, and record the emission intensity value; Total nutrient calculation formula:

[0043] Table 3. Results of total nutrient mass fraction determination for the examples and comparative examples.

[0044] Determination of organic matter content: Take 0.2g of sample and add it to a test tube. Add 10mL of 0.4mol / L potassium dichromate-sulfuric acid solution, heat to 180℃, boil for 5min, cool to room temperature, add o-phenanthroline indicator, and titrate with ferrous sulfate standard solution until the solution changes from orange-red to blue-green to brick-red as the endpoint. At the same time, perform a blank test and calculate the organic matter content (%) based on the amount of ferrous sulfate consumed. Moisture content determination: Take 5.0g of sample and place it in an aluminum box. Place the box in a constant temperature drying oven, heat it to 105℃±2℃, and dry it for 6 hours. After drying, remove the box and place it in a desiccator to cool to room temperature. Record the mass. The formula for calculating the moisture content is: pH test: Take 10.0g of sample and add it to a 100mL beaker. Add 50mL of deionized water, stir for 5min, let stand for 30min, and use a pH meter to test the pH value of the supernatant. Table 4. Measurement results of the examples and comparative examples

[0045] Determination of heavy metal content: Inductively coupled plasma mass spectrometry was used. Take 0.5g of sample, add 8mL of concentrated nitric acid and 2mL of hydrogen peroxide, let stand overnight for digestion, put it into a microwave digester, heat to 120℃, hold for 5min, heat to 160℃, hold for 5min, heat to 190℃, hold for 20min, digestion is complete, cool to room temperature, put into a 50mL volumetric flask, add deionized water to make up to the mark, mix well and perform inductively coupled plasma mass spectrometry detection; Table 5. Measurement results of the examples and comparative examples

[0046] Fecal coliform assay: Take 10.0g of sample, place it in a sterile mortar, add sterile water and grind evenly. After grinding, add sterile water to make up to 100mL. Take 10g of the sample. -1 10 mL of diluent was injected into 5 test tubes containing 10 mL of double-strength lactose bile salts. Then, 10 mL of the solution was added. -1 1 mL of diluent was injected into 5 test tubes containing 10 mL of double-strength lactose bile salts. 10 test tubes were prepared using the same method. -2 Diluent, 5 test tubes in total, 15 test tubes were placed in a water bath and heated to 44.5±0.5℃ for 24 hours. The fecal coliform count (CFU / g) was then calculated. Ascaris egg mortality rate determination: Take 10g of sample, add 50mL of deionized water, stir to make a suspension, pass through 40-mesh and 100-mesh sieves successively, collect the sieve residue, place it on a glass slide, observe it under a microscope, count the number of live and dead Ascaris eggs, count 200g of Ascaris eggs, and calculate the mortality rate of Ascaris eggs using the following formula: Table 6. Measurement results of the examples and comparative examples

[0047] Dust emission concentration test: Refer to the HJ / T 397-2007 testing standard; The initial dust concentration C0 entering the dust removal unit was measured on the straight section of the main air inlet pipe of the pulse dust removal unit in Examples 1-3 and Comparative Examples 1-5, respectively. The residual dust concentration C1 after gravity settling was measured on the straight section of the connecting pipe between the outlet of the first-stage gravity settling section and the inlet of the second-stage filter bag filtration section. The residual dust concentration C2 after filter bag filtration was measured on the straight section of the connecting pipe between the outlet of the second-stage polytetrafluoroethylene membrane filter bag filtration section and the inlet of the third-stage high-voltage pulse electric field adsorption section. The final emission dust concentration C3 was measured on the straight section of the outlet pipe of the third-stage high-voltage pulse electric field adsorption section. Three groups of valid samples were collected within a 72-hour period. Each group was sampled every 15 minutes for 1 hour, for a total of 4 times, with each sampling time being 10 minutes. Formulas for calculating concentration at various points:

[0048] Where: C is the dust concentration, mg / m³ 3 V nd The standard dry flue gas sampling volume is in L; Efficiency calculation formula: First-order settlement efficiency: Secondary settlement efficiency: Third-level settlement efficiency: Overall dust removal efficiency: Ash resource utilization rate test: Weigh the percentage (%) of the ash mass actually recycled into the finished organic fertilizer in step S7 of Examples 1-3 and Comparative Examples 1-5, and weigh and record the ash discharged from the combustion chamber that was not recycled. Table 7. Measurement results of the examples and comparative examples

[0049] Data Analysis: As can be seen from Tables 1-7, the chicken manure drying method of the present invention performs excellently in terms of system energy consumption, drying temperature stability, exhaust gas purification efficiency, total nutrient content of organic fertilizer and ash resource utilization rate. In contrast, Comparative Example 1, which did not dynamically feedforward adjust the split ratio based on the initial moisture content of fresh chicken manure but instead used a fixed split ratio, resulted in poor system thermal balance adaptability, frequent start-stop of auxiliary electric heating, large fluctuations in heating temperature, and increased energy consumption. This is because the fixed split ratio cannot synchronously adjust the amount of reburning fuel supply according to fluctuations in the moisture content of the raw materials: when the moisture content is too high, there is insufficient reburning fuel, requiring additional power consumption to compensate for the heat gap; when the moisture content is too low, excessive fuel causes excess heat energy waste. At the same time, large fluctuations in hot air temperature directly cause uneven drying of materials, affecting the batch consistency of finished product quality. In addition, the system has poor resistance to changes in the moisture content of raw materials and cannot adapt to the actual production conditions of large-scale farms where the moisture content of chicken manure fluctuates with the seasons and feeding processes, resulting in insufficient operational stability. Comparative Example 2, by omitting the three-stage gradient heat exchange system and using only a single-stage heat exchange to cool the high-temperature flue gas once, resulted in the combustion air distribution not being preheated to their respective suitable temperature ranges, low system heat recovery efficiency, and a significant increase in auxiliary electric heating compensation. This is because the single-stage heat exchange cannot achieve the graded extraction and matching utilization of the sensible heat of the high-temperature flue gas: the primary and secondary air were not preheated to the optimal air distribution temperature, and the ignition conditions and combustion efficiency of the combustion chamber both decreased; at the same time, a large amount of waste heat from the high-temperature flue gas was directly emitted, resulting in serious waste of waste heat resources, and the temperature of the clean hot air after the single-stage heat exchange was low and fluctuated drastically, which could not meet the drying drum's demand for a stable hot air supply. In addition, the system's dependence on external electric heating increased significantly, resulting in poor operating economy and violating the original design intention of the present invention for energy self-circulation. Comparative Example 3, by omitting the third-stage high-voltage pulse electric field adsorption section of the pulse dust removal unit and retaining only the two-stage physical purification of gravity settling and filter bag filtration, resulted in the penetration and emission of submicron dust, a significant increase in particulate matter emission concentration, and a decrease in overall dust removal efficiency. This is because the gravity settling stage is only effective for coarse particles with a diameter >50μm. While PTFE-coated filter bags have good filtration effects for fine particles of 0.5-50μm, their capture efficiency for submicron dust with a diameter ≤0.5μm is limited. Without the high-voltage pulse electric field adsorption section, ultrafine dust in this particle size range cannot be effectively removed. At the same time, the load on the two-stage physical purification increases, and the service life of the filter bags may be shortened due to accelerated dust penetration. In addition, the ultrafine dust remaining in the exhaust gas will adhere to the catalyst surface of the subsequent wet desulfurization and SCR reactor, affecting the desulfurization efficiency and denitrification catalyst activity, causing a cascading negative impact on downstream purification equipment.

[0050] Comparative Example 4, by failing to recycle the combustion ash into the finished organic fertilizer and instead disposing of it directly as solid waste, resulted in a significant reduction in the total nutrients and phosphorus and potassium content of the finished organic fertilizer, a weakened pH buffering capacity, and a waste of mineral resources. This is because ash is rich in plant nutrients such as P2O5 and K2O, and its weak alkalinity provides pH regulation; without recycling, these nutrients and beneficial components are completely lost, rendering the finished fertilizer ineffective in enhancing nutrients and improving quality. Furthermore, ash discharge not only wastes resources but also increases solid waste disposal costs and environmental burden. In addition, trace elements such as silicon, calcium, and magnesium are also lost in the ash, weakening the comprehensive improvement effect of organic fertilizer on soil physicochemical properties and reducing the product's market competitiveness and added value. Comparative Example 5, due to the omission of the low-temperature SCR reactor denitrification step, resulted in the direct emission of nitrogen oxides and NO in the exhaust gas without reduction treatment. x The emission concentration was much higher than in the various embodiments because neither the wet scrubbing desulfurization nor the bio-trickling filtration deodorization process produces NO. x Removal capacity: After omitting the SCR reactor, the NO generated during the combustion of chicken manure fuel is reduced. x It cannot be selectively catalytically reduced to N2 and H2O and is directly discharged into the atmosphere. While the pre-processing pulse dust collector and wet desulfurization can remove particulate matter and SO2, they are ineffective against NO. x It has no removal effect whatsoever; the post-filter biological deodorization tower only targets malodorous gases and is equally ineffective against NO. x Ineffective; the absence of a low-temperature SCR reactor creates a gap in the entire purification chain at the nitrogen oxide control stage. Furthermore, NO... x Exceeding emission concentration limits will prevent the entire exhaust gas treatment system from meeting increasingly stringent air pollutant emission standards, resulting in a significant defect in the environmental compliance of this invention and affecting the legal implementation and promotion of the technology.

[0051] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0052] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for drying chicken manure, characterized in that, The specific steps of the processing method are as follows: Step S1: In a sealed state, add fresh chicken manure into the receiving chamber, control the relative pressure of the receiving chamber to -30Pa to -80Pa, place it on a vibrating screen with a screen mesh size of 8-15mm, place it in a mixer and disperser, rotate at 40-80rpm, and stir for 5-15min. After stirring is completed, dispersed chicken manure is obtained. Step S2: Add the dispersed chicken manure into the drying drum. The drum rotates at 3-8 rpm. For the first batch, start the auxiliary heat source and heat the air to 95-105℃. Hold for 25-45 minutes and dry until the output moisture content is ≤15% to obtain dry chicken manure. Step S3: Add the dried chicken manure to the pneumatic three-way distributor, preset the splitting ratio, and transport the first part of the chicken manure, which accounts for 30%-40% of the total mass of dried chicken manure, to the fuel storage bin of the drying drum, and transport the remaining 60%-70% of the second part of the chicken manure to the finished product bin as raw material for organic fertilizer biomass. Step S4: In subsequent batch processing, repeat step S1 and the operation of feeding loose chicken manure into the drying drum, ignite the dried chicken manure in the fuel storage bin, use staged air distribution for combustion, with an excess air coefficient of 1.15-1.30, a combustion temperature of 850-1050℃, and a combustion chamber pressure of -50Pa to -150Pa, to obtain high-temperature flue gas, ash and exhaust gas. Step S5: High-temperature flue gas is introduced into a three-stage gradient heat exchange system, and clean air heat exchange medium is introduced. The flue gas is cooled to 120-150℃, and the clean air is heated to 80-120℃, resulting in low-temperature flue gas and clean hot air. Step S6: The low-temperature flue gas and exhaust gas are passed into the first-stage Venturi, condensed and washed, and cooled to 60-80℃. They are then sequentially processed by a pulse dust collector, chemically removed by a wet scrubbing absorption tower, denitrified by a low-temperature SCR reactor, and biologically deodorized by a bio-trickling filter deodorization tower. After the treatment is completed, clean exhaust gas is obtained. Step S7: Cool the ash to 50-60℃ and send it into the finished product silo in step S3 through a pneumatic conveying device to mix it with the organic fertilizer biomass raw materials to obtain phosphorus and potassium rich organic fertilizer.

2. The method for drying chicken manure according to claim 1, characterized in that, The preset splitting ratio R, which accounts for 30%-40% of the total mass of dried chicken manure in step S3, has a base setting value R0 of 35%. The preset split ratio is dynamically feedforward corrected according to the initial moisture content ω1 of the fresh chicken manure in step S1, that is, the moisture content of the loose chicken manure before entering the drying drum, according to the following rules: When ω1≥75%, R=37%-40%; When 65%≤ω1<75%, R=33%-37%; When ω1 < 65%, R = 30% - 33%; The specific formula for calculating the value of R is as follows: ω1 is substituted as a percentage value, and the calculation result is limited to a closed interval of 30%-40%.

3. The method for drying chicken manure according to claim 1, characterized in that, The specific method of staged air distribution combustion described in step S4 is: a combined supply of primary and secondary air; The volume ratio of the primary air to the secondary air is 55-65:45-35; The primary air is introduced from the swirl plate at the bottom of the combustion chamber, carrying chicken manure fuel and rising in a vortex; The secondary air is injected tangentially from the circumferentially distributed air inlets in the center of the combustion chamber.

4. The method for drying chicken manure according to claim 1, characterized in that, The specific method of the three-stage gradient heat exchange in step S5 is as follows: the first-stage heat exchanger is made of heat-resistant stainless steel 310S, which raises the temperature of the primary air to 200-250℃. The secondary heat exchanger is made of heat-resistant stainless steel 304, which raises the temperature of the secondary air to 150-180℃; The three-stage heat exchanger is made of galvanized carbon steel tubes and heats clean air to 80-120℃.

5. The method for drying chicken manure according to claim 1, characterized in that, The specific method of condensation washing described in step S6 is as follows: low-temperature flue gas and tail gas are introduced into a Venturi condensation washing tower, and spray washing is performed using circulating cooling water at 20-25℃, with a spray liquid-to-gas ratio of 3-8 L / m³. 3 The condensate is recovered and used as makeup water for the cooling tower.

6. The method for drying chicken manure according to claim 1, characterized in that, The recycling process of the pulse dust removal unit in step S6 is specifically as follows: the low-temperature flue gas and exhaust gas are introduced into the pulse dust collector for three-stage physical purification. In the first stage of gravity settling, the apparent flow velocity is 0.3-0.5 m / s, and coarse dust with a particle size > 50 μm settles. The second-stage PTFE membrane filter bag filtration section filters fine dust with a filtration velocity of 0.8-1.2 m / min and a particle size of 0.5-50 μm. The third-stage high-voltage pulsed electric field adsorption section operates at a voltage of 30-50kV, a pulse frequency of 40-80Hz, and an adsorption particle size of ≤0.5μm.

7. The method for drying chicken manure according to claim 1, characterized in that, The specific methods for chemical deep removal using a wet scrubbing absorption tower, denitrification using a low-temperature SCR reactor, and biological deodorization using a bio-trickling filtration deodorization tower described in step S6 are as follows: Low-temperature flue gas and tail gas after pulse dust removal are introduced into a scrubbing absorption tower for limestone-gypsum desulfurization. The gas is then placed in a primary steam heat exchanger and heated to 180-220℃. It is then introduced into a low-temperature SCR reactor, where ammonia water (a reducing agent) and a vanadium-based low-temperature denitrification catalyst are added for denitrification. Finally, the gas is introduced into a bio-trickling filtration deodorization tower filled with polyurethane biological sponge packing. The packing surface contains malodorous Pseudomonas aeruginosa and nitrifying bacteria, ensuring that the NH3 concentration in the outlet gas is ≤5 mg / m³. 3 H2S concentration ≤ 0.5 mg / m³ 3 .

8. The method for drying chicken manure according to claim 1, characterized in that, The receiving chamber mentioned in step S1 is a fully enclosed steel structure with a breathing valve and a negative pressure ventilation system at the top. The ammonia-containing air extracted is introduced into the waste gas treatment system in step S6.

9. A method for drying chicken manure according to claim 1, characterized in that, In step S7, the ash contains ≥8% P2O5 and ≥12% K2O. The mass ratio of the ash to the organic fertilizer biomass raw material is 1:12-18.

10. A method for drying chicken manure according to claim 1, characterized in that, The fuel storage bin described in step S4 is equipped with an insulation jacket and a material level sensor. A variable frequency screw feeder is installed at the bottom of the bin. Dry hot air at 40-50℃, which has been preheated by a heat exchanger, is introduced into the bin for protection. The drying cylinder is an inclined rotating cylinder with a length-to-diameter ratio of 8-12 and an inclination angle of 3°-6°.

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