ENVIRONMENTALLY FRIENDLY EMISSION SYSTEM FOR A KITCHEN WASTE INCINERATOR

Description

FIELD

The present invention relates to the technical field of kitchen waste incineration technology, and particularly to an environmentally friendly emission system for a kitchen waste incinerator.

BACKGROUND

With the rapid growth of the national economy and the acceleration of urbanization processes, the production volume of municipal solid waste has increased dramatically. According to data from China's National Bureau of Statistics, since 2008, the disposal and transportation volume of municipal domestic waste has increased year by year. By 2018, the total volume of municipal solid waste in China had reached 228 million tons, representing a year-on-year increase of 5.59%. Waste treatment has already become a critical issue for urban development. The composition of municipal solid waste is subject to seasonal and regional influences, exhibiting relatively large fluctuations, but its overall composition is relatively stable, consisting mainly of rubber, paper, plastics, food waste, and biomass waste, among others. Its average water content is low, and its calorific value is high. Therefore, the use of the incineration method to treat municipal solid waste has already gained widespread application.

The production volume of kitchen waste within municipal solid waste is increasing year by year. Because the water content of kitchen waste is far higher than that of ordinary municipal solid waste, it consequently has a low calorific value and is difficult to ignite. Ordinary municipal solid waste incinerators are no longer suitable for it, and there is an urgent need to develop an energy-saving type of kitchen waste incinerator capable of achieving environmentally friendly emissions.

In the prior art, in order to solve the aforementioned technical problem, the Chinese invention patent application with application number 202311575910.8 discloses a waste incinerator energy-saving combustion system, comprising a waste incinerator, a sludge heating device, a waste leachate pool, a water tank, and a heat exchanger, among others. The sludge heating device is connected via a conveyor belt to the feed hopper of the waste incinerator, conveying heated sludge into the waste incinerator for combustion. Tube bundles are installed on the upper side wall of the furnace chamber of the waste incinerator. The tube bundles include a first tube bundle and a second tube bundle. The water tank is connected through a first water pump to the water inlet of the first tube bundle, and the water outlet of the first tube bundle is connected to the water tank, forming a first heated water circulation. The water tank is connected through a second water pump to the water inlet of the second tube bundle, the water outlet of the second tube bundle is connected to the sludge heating device, and the sludge heating device is connected to the water tank, forming a second heated water circulation. Installing the said tube bundles on the inner side wall of the upper part of the furnace chamber is used for absorbing local high temperatures inside the furnace chamber, preventing the phenomenon of furnace chamber inner wall coking caused by local high temperatures, and effectively prolonging the service life of the waste incinerator; simultaneously, the heat absorbed by the tube bundles is utilized for heating the sludge heating device, and so on. Although the aforementioned technical solution has the advantages of effectively reducing the energy consumption for sludge drying, being able to ensure the stable combustion of low calorific value domestic waste, sludge and waste leachate without increasing the use of high calorific value auxiliary fuel, and having an extremely low content of dust and nitrogen oxide in the flue gas generated by combustion which allows for direct emission, showing significant environmental benefits, the nitrogen oxide emission pollution therein is however severe, proving that reducing nitrogen oxide emissions is a technical problem urgently needing resolution, and the prior art temporarily also has no corresponding literature reports.

SUMMARY

The purpose of the present invention is, aiming at the deficiencies existing in the above-mentioned prior art, to provide an environmentally friendly emission system for a kitchen waste incinerator, specially used for kitchen waste treatment, which can save solid waste treatment costs, and reduce nitrogen oxide generation and energy consumption.

The technical solution adopted by the present invention is: an environmentally friendly emission system for a kitchen waste incinerator, comprising a waste incinerator, a dry desulfurization tower, a dust collector, and a chimney. A flue gas emission pipe of the waste incinerator is connected to the dry desulfurization tower, an outlet of the dry desulfurization tower is connected to an inlet of the dust collector, and an outlet of the dust collector is connected to the chimney; a high-temperature heat exchanger and a low-temperature heat exchanger are sequentially provided on the flue gas pipeline between the waste incinerator and the dry desulfurization tower, a branch recirculation pipeline is provided on the pipeline between the high-temperature heat exchanger and the low-temperature heat exchanger and is connected to an inlet of a recirculation fan, and the outlet of the recirculation fan are respectively connected to each air chamber provided on the waste incinerator through pipeline.

A plurality of air chambers is arranged at the lower part of the furnace chamber of the waste incinerator. Each air chamber is provided with a recirculated flue gas inlet, a primary air inlet, a primary baffle, and a secondary baffle. The primary baffle is provided in the middle of the inner cavity of the air chamber and is located above the recirculated flue gas inlet; the primary air inlet is provided on the bottom wall surface of the air chamber, between the primary baffle and the secondary baffle.

A passage is formed between the primary baffle and the inner side wall of the air chamber.

The edge of the primary baffle is provided with a downwardly bent bending part, which redirects and mixes the head-on injected recirculated flue gas before it overflows from the passage, causing the recirculated flue gas to impact the primary baffle and form turbulent flow; the primary baffle is installed at the 1/2 height of the air chamber, has a width of 1/2 of the air chamber width at the same height, has a downward inclination angle of 30-60 degrees, and is positioned at a height of 1/4 of the total height of the air chamber from the bottom.

The secondary baffle is provided on the side wall of the air chamber above the primary baffle, and a mixed gas passage is formed in the middle of the secondary baffle and is connected to the furnace chamber. The secondary baffle is installed at the 3/4 height of the air chamber and is divided into two pieces: left and right, and the width of each piece is 1/4 of the air chamber width at the same height.

The dry desulfurization tower comprises a tower body and a plurality of tangential nozzles provided on the side of the tower body, the tangential nozzles are connected to an ejector, a high-pressure inlet of the ejector is connected to an outlet of an air compressor, an ejection inlet of the ejector is connected via a pipeline to a powder silo, and the powder silo contains sodium bicarbonate powder; the tangential nozzles are provided at a height of 60-80% of the total height from the bottom of the desulfurization tower; the number of the tangential nozzles is 6-12, and their inclination angle is 30-60 degrees.

Also included is a waste pre-treatment module, which is connected to the waste incinerator via a screw conveyor device; the waste pre-treatment module comprises a waste sorting unit, a drying unit, and an organic substance treatment unit, the waste sorting unit is connected to the drying unit, the waste sorting unit comprises a waste storage bin and a sorting device, and the waste storage bin is connected to the sorting device; the sorting device is connected to the treatment unit; the treatment unit is provided with an oil delivery pipe connected to an external transport module, and the treatment unit is provided with a liquid delivery pipe connected to a sewage treatment tank.

An organic residue outlet of the treatment unit is connected to an organic substance treatment unit via an organic residue conveyor pipe; the organic substance treatment unit includes an anaerobic tank, the organic residue conveyor pipe is connected to the inlet of the anaerobic tank, and a biogas outlet of the anaerobic tank is connected to a combustion mixing device via a conveyor pipe.

The chimney is provided with a branch pipeline that is connected to the air chamber of the drying unit through a second fan; an exhaust port of the drying chamber is connected to the furnace chamber of the waste incinerator through a third fan; the combustion mixing device comprises a combustion mixing chamber and a burner provided on the inner side wall of the combustion mixing chamber, and the biogas outlet of the anaerobic tank is connected to a fuel inlet of the burner through a conveyor pipe.

Also included is a hot air generation device, the hot air generation device comprises a solar thermal energy storage circulation device and a ceramic electric radiation heat accumulator, the solar thermal energy storage circulation device comprises a solar photovoltaic power generation module and a heat storage circulation module, the heat storage circulation module comprises an electric heater, a high-temperature molten salt tank, a heat exchanger, and a low-temperature molten salt tank, the electric heater is connected to the high-temperature molten salt tank, the high-temperature molten salt tank is connected to the heat exchanger through a first molten salt pump, the heat exchanger is connected to the low-temperature molten salt tank, and the low-temperature molten salt tank is connected to the electric heater through a second molten salt pump, forming a heat storage circulation loop; the solar photovoltaic power generation module is connected to the electric heater; the ceramic electric radiation heat accumulator is connected to a power grid; an air intake pipe is connected to the heat exchanger through a fourth fan, a hot air outlet of the heat exchanger is connected to an air inlet of the ceramic electric radiation heat accumulator, an outlet of the ceramic electric radiation heat accumulator is connected to a mixer, the mixer is connected to the air chambers, and the mixer is connected to a first fan.

The ceramic electric radiation heat accumulator comprises a tank body, ceramic heat storage bodies, and an electric heater, a plurality of the ceramic heat storage bodies are installed inside the tank body, gaps are reserved between adjacent ceramic heat storage bodies to form air heating channels, and the electric heater is installed inside the ceramic heat storage bodies, storing the heat released by the electric heater in the ceramic heat storage bodies. Preferably, two separator plates are provided inside the tank body, and the ceramic heat storage bodies are fixed between the two separator plates; an air inlet chamber and an air outlet chamber are respectively formed between the two separator plates and the upper and lower walls of the tank body, an air inlet port is provided on the air inlet chamber, an air outlet port is provided on the air outlet chamber, and air through holes are provided between the air inlet chamber and the air outlet chamber and the air heating channels.

Overall, compared with the prior art, the beneficial effects possessed by the present invention are as follows: high-temperature flue gas accounting for 10% of the total amount is extracted in the flue duct and mixed with primary air in the air chambers, featuring high temperature, low oxygen content, intense combustion, and low nitrogen oxide generation; the high-temperature flue gas can increase the primary air temperature, reduce the consumption of steam for primary air heating, and lower energy consumption; the air chamber is equipped with a primary baffle and a secondary baffle, and the recirculated flue gas impacts the primary baffle to form turbulent flow which uniformly mixes with the primary air in the space between the primary and secondary baffles to form a high-temperature, low-oxygen gas; a sodium bicarbonate dry desulfurization tower is installed in the tail flue, and the flue gas after desulfurization has low fly ash content, saving the treatment cost of hazardous waste (fly ash generated by the waste incinerator); in addition, the use of solar photovoltaic power generation and the utilization technology of extremely cheap off-peak electricity at night to generate high-temperature primary air can further reduce the consumption of steam for primary air heating and reduce energy consumption.

BRIEF DESCRIPTION OF DRAWINGS

For a clearer illustration of the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below pertain to some embodiments of the present invention. For those of ordinary skill in the art, other drawings may also be obtained based on these drawings without exerting creative effort.

FIG. 1 is a flow diagram 1 of the environmentally friendly emission system for a waste incinerator according to the present invention;

FIG. 2 is a cross-sectional view taken along section A-A;

FIG. 3 is a flow diagram 2 of the environmentally friendly emission system for a waste incinerator according to the present invention;

FIG. 4 is a flow diagram 3 of the environmentally friendly emission system for a waste incinerator according to the present invention;

FIG. 5 is a cross-sectional structural diagram of the ceramic electric radiation heat accumulator.

DETAILED DESCRIPTION

The technical solutions of the present invention will be described clearly and completely in combination with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention. In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and other indications of orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limitations to the present invention.

Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined by "first" or "second" may explicitly or implicitly include one or more of said features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly and specifically defined otherwise. In addition, the terms "install", "connect", and "link" should be interpreted broadly; for example, they may be a fixed connection, or may be a detachable connection, or an integral connection; they may be a mechanical connection, or may be an electrical connection; they may be a direct connection, or may be an indirect connection through an intermediate medium; they may be an internal connection between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention based on the specific circumstances.

An environmentally friendly emission system for a kitchen waste incinerator, as shown in FIG. 1, comprises a waste incinerator 1, a high-temperature heat exchanger 2, a low-temperature heat exchanger 3, a dry desulfurization tower 4, a dust collector 9, a chimney 8, among others. A flue gas emission pipe of the waste incinerator 1 is connected to the dry desulfurization tower 4; an outlet of the dry desulfurization tower 4 is connected to an inlet of the dust collector 9; an outlet of the dust collector 9 is connected to the chimney 8, discharging the purified waste gas. The high-temperature heat exchanger 2 and the low-temperature heat exchanger 3 are sequentially provided on the flue gas pipeline between the waste incinerator 1 and the dry desulfurization tower 4. A branch recirculation pipeline is provided on the pipeline between the high-temperature heat exchanger 2 and the low-temperature heat exchanger 3 and is connected to an inlet of a recirculation fan 10; the outlet of the recirculation fan 10 are respectively connected to each air chamber 12 provided on the waste incinerator 1 through pipeline, introducing the high-temperature flue gas accounting for 10% of the total amount in the flue duct to mix with primary air in the air chambers 12 before entering the furnace chamber to support combustion, causing high temperature, low oxygen content, intense combustion, and low nitrogen oxide generation inside the furnace chamber. Cold water passes sequentially through the low-temperature heat exchanger 3 and the high-temperature heat exchanger 2 via pipelines, and the cold water is gradually heated to produce steam for other purposes.

A plurality of air chambers 12 are arranged at the lower part of the furnace chamber of the waste incinerator 1, the air chambers 12 are provided with a recirculated flue gas inlet and a primary air inlet, and the high-temperature flue gas accounting for 10% of the total amount are mixed with the primary air inside the air chambers and are then fed into the furnace chamber to support combustion. A primary baffle 15 and a secondary baffle 13 are installed inside the air chamber 12, and the primary baffle 15 is installed in the middle of the inner cavity of the air chamber 12 and is located above the recirculated flue gas inlet. A passage 14 is formed between the primary baffle 15 and the inner side wall of the air chamber 12. Preferably, the edge of the primary baffle 15 is provided with a downwardly bent bending part, which redirects and mixes the head-on injected recirculated flue gas before it overflows from the passage 14, causing the recirculated flue gas to impact the primary baffle 15 and form turbulent flow, thereby promoting more uniform mixing of the combustion-supporting mixed gas. The secondary baffle 13 is provided on the side wall of the air chamber 12 above the primary baffle 15, and a mixed gas passage is formed in the middle of the secondary baffle 13 and is connected to the furnace chamber. The primary air inlet is provided on the bottom wall surface of the air chamber, between the primary baffle 15 and the secondary baffle 13. The primary baffle 15 and the secondary baffle 13 installed in the air chamber 12 cause the recirculated flue gas to impact the primary baffle 15 and then uniformly mix with the primary air in the space between the primary baffle 15 and the secondary baffle 13 to form a high-temperature, low-oxygen gas. The primary baffle 15 is installed at the 1/2 height of the air chamber 12, has a width of 1/2 of the air chamber width at the same height, has a downward inclination angle of 30-60 degrees, and is positioned at a height of 1/4 of the total height of the air chamber from the bottom. The secondary baffle 13 is installed at the 3/4 height of the air chamber 12 and is divided into two pieces: left and right, and the width of each piece is 1/4 of the air chamber width at the same height.

The dry desulfurization tower 4, as shown in FIG. 2, comprises a tower body and a plurality of tangential nozzles 41 provided on the side of the tower body, the tangential nozzles are connected to an ejector 5, a high-pressure inlet of the ejector 5 is connected to an outlet of an air compressor 7, an ejection inlet of the ejector 5 is connected via a pipeline to a powder silo 6, and the powder silo 6 contains sodium bicarbonate powder. Preferably, the number of the tangential nozzles 41 is 10, their inclination angle is 45 degrees, and they are provided at a height of 70% of the total height of the desulfurization tower from the bottom. High-pressure air aspirates the sodium bicarbonate powder through the ejector 5 and enters the desulfurization tower 4 through the nozzles 41. In the desulfurization tower 4, the powdered sodium bicarbonate reacts with sulfides in the flue gas to carry out the desulfurization reaction. By installing the sodium bicarbonate dry desulfurization tower 4 in the tail flue, the flue gas after desulfurization has low fly ash content, saving the treatment cost of hazardous waste (fly ash generated by the waste incinerator).

As shown in FIG. 3, the present invention also includes a waste pre-treatment module. The waste pre-treatment module is connected to the waste incinerator 1 via a screw conveyor device 33, conveying the sorted and dried waste into the waste incinerator 1 for combustion. The waste pre-treatment module comprises a waste sorting unit, a drying unit, and an organic substance treatment unit. The waste sorting unit is used for sorting the kitchen waste into large pieces of wet waste and small fine waste such as leachate. The waste sorting unit is connected to the drying unit, conveying the large pieces of wet waste into the drying chamber 27 of the drying device 30 of the drying unit for drying treatment, and then feeding them into the waste incinerator 1 for combustion. The waste sorting unit comprises a waste storage bin 26 and a sorting device 25, and the waste storage bin 26 is connected to the sorting device 25, conveying the collected waste into the sorting device 25 for sorting. The sorting device 25 can be a centrifugal sorter. The sorting device 25 is connected to the treatment unit 20, conveying the sorted small fine materials such as leachate into the treatment unit 20 for oil-water separation treatment. The treatment unit 20 is an oil-water separator, provided with an oil delivery pipe 23 connected to an external transport module 24, and the external transport module can be an oil storage tank. The treatment unit 20 is provided with a liquid delivery pipe 21 connected to a sewage treatment tank 22, conveying the separated sewage into the sewage treatment tank 22 for storage and pending treatment.

An organic residue outlet of the treatment unit 20 is connected to the organic substance treatment unit via an organic residue conveyor pipe 19, conveying the organic residue into the organic substance treatment unit for treatment. The organic substance treatment unit comprises an anaerobic tank 18, the organic residue conveyor pipe 19 is connected to the inlet of the anaerobic tank 18, and a biogas outlet of the anaerobic tank 18 is connected to a combustion mixing device via a conveyor pipe for burning the generated biogas to heat air.

Herein, the drying unit 30 comprises a drying chamber 27 and an air chamber 29 provided below the drying chamber 27, and the air chamber 29 is provided with through holes connected to the drying chamber 27, conveying the hot air inside the air chamber 29 into the drying chamber 27 to dry the waste. Preferably, air caps 28 are provided on the through holes to prevent clogging of the through holes and to achieve better drying effect.

Preferably, the chimney 8 is provided with a branch pipeline that is connected to the air chamber 29 of the drying unit 30 through a second fan 34 for introducing part of the flue gas with a temperature as high as 150°C to dry the material in the drying chamber 27. An exhaust port of the drying chamber 27 is connected to the furnace chamber of the waste incinerator 1 through a third fan 31, directly feeding the hot exhaust gas from the drying chamber 27 into the waste incinerator 1 for combustion, heat release, and purification, which can effectively reduce the generation of NOX; since the amount of the exhaust gas is very small, this part of humid hot exhaust gas does not affect the temperature inside the furnace chamber. Preferably, the combustion mixing device comprises a combustion mixing chamber 16 and a burner 17 provided on the inner side wall of the combustion mixing chamber 16, and the biogas outlet of the anaerobic tank 18 is connected to a fuel inlet of the burner 17 via a conveyor pipe. The biogas generated by the anaerobic tank 18 is burned by the burner 17, and within the combustion mixing chamber 16, the incoming 150°C flue gas is heated to 300°C, and then introduced into the drying unit 30 to dry the material to be dried.

As shown in FIG. 4, the present invention also includes a hot air generation device, the hot air generation device comprises a solar thermal energy storage circulation device and a ceramic electric radiation heat accumulator 43 that uses cheap off-peak electricity for heat storage, the solar thermal energy storage circulation device comprises a solar photovoltaic power generation module 44 and a heat storage circulation module, the heat storage circulation module comprises an electric heater 40, a high-temperature molten salt tank 41, a heat exchanger 36, and a low-temperature molten salt tank 38, the electric heater 40 is connected to the high-temperature molten salt tank 41, the high-temperature molten salt tank 41 is connected to the heat exchanger 36 through a first molten salt pump 42, the heat exchanger 36 is connected to the low-temperature molten salt tank 38, and the low-temperature molten salt tank 38 is connected to the electric heater 40 through a second molten salt pump 39, forming a heat storage circulation loop. Herein, the medium in the heat storage circulation pipeline is a KNO₃+NaNO₃ with temperature at 350°C-600°C. The solar photovoltaic power generation module 44 is connected to the electric heater 40, providing power for the electric heater 40.

The ceramic electric radiation heat accumulator 43 is connected to a power grid 45. The heat generated by electric heating is used to heat the ceramic heat storage bodies in the ceramic electric radiation heat accumulator 43 to above 1000°C. An air intake pipe is connected to the heat exchanger 36 through a fourth fan 37, using the heat of the high-temperature molten salt to heat the 20°C cold air to 500°C hot air, and a hot air outlet of the heat exchanger 36 is connected to an air inlet of the ceramic electric radiation heat accumulator 43, using the heat release from the ceramic heat storage bodies to heat the 500°C hot air to 900°C. An outlet of the ceramic electric radiation heat accumulator 43 is connected to a mixer 35, and the mixer 35 is connected to the air chambers 12. The mixer 35 is connected to a first fan 11 for introducing 20°C cold air to mix in the mixer 35 to produce 200°C hot air. Based on the above structure, the system operation of the present invention is as follows: When there is sunlight during the daytime, the solar photovoltaic power generation module operates to generate electricity while simultaneously heating the molten salt via the heat storage circulation module for heat storage and also heating the air; from 24:00 at night to 8:00 in the morning, which is the off-peak electricity period, power is supplied from the grid to the ceramic electric radiation heat accumulator 43 to heat the air and simultaneously heat the ceramic heat storage bodies for heat storage; between sunset and 24:00 at night, heating is provided by the heat stored in the ceramic heat storage bodies in the ceramic electric radiation heat accumulator 43 and the liquid molten salt in the high-temperature molten salt tank simultaneously. This fully utilizes the cheap energy of solar power and off-peak electricity, reducing emissions while saving energy.

As shown in FIG. 5, the ceramic electric radiation heat accumulator 43 comprises a tank body 438, ceramic heat storage bodies 433, and an electric heater 435, a plurality of the ceramic heat storage bodies 433 are installed inside the tank body 438, and air heating channels 434 are formed between adjacent ceramic heat storage bodies 433, transferring the heat stored in the ceramic heat storage bodies 433 to the air through the air heating channels 434; the electric heater 435 is installed inside the ceramic heat storage bodies 433, storing the heat released by the electric heater in the ceramic heat storage bodies 433. Preferably, two separator plates are provided inside the tank body 438, the ceramic heat storage bodies 433 are fixed between the two separator plates, an air inlet chamber 432 and an air outlet chamber 436 are respectively formed between the two separator plates and the upper and lower walls of the tank body 438, an air inlet port 431 is provided on the air inlet chamber 432, an air outlet port 437 is provided on the air outlet chamber 436, and air through holes 437 are provided between the air inlet chamber 432 and the air outlet chamber 436 and the air heating channels 434.

The above embodiments are merely used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: They can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some or all of the technical features therein; such modifications or replacements do not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention.