System and method for drying household garbage by using flue gas waste heat of coal-fired boiler

Abstract

The invention provides a system and a method for drying household garbage by using flue gas waste heat of a coal-fired boiler, in the system, an inlet of a garbage rotary drying device is connected with a tail flue of an air pre-heater, and an outlet of the garbage rotary drying device is connected with a front flue of an induced draft fan; wet household garbage in the garbage rotary drying device is dried through waste heat of waste smoke led out from the tail of the air pre-heater, and the waste smoke after heat exchange carries garbage water vapor to enter the desulfurization device to be purified under the traction of the induced draft fan. According to the system, the drying process of the household garbage is coupled with the coal-fired boiler, on one hand, recycling of flue gas waste heat of the coal-fired boiler can be improved, and energy waste is reduced; and on the other hand, drying treatment of the household garbage can be achieved, the garbage rotary drying device operates under the negative pressure condition by means of the pressure difference between different devices of the coal-fired boiler, and leakage of peculiar smells of the garbage is avoided. According to the system, by means of a tail gas purification system of the coal-fired boiler, efficient co-treatment of garbage drying tail gas can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy recovery of coal-fired boilers, and in particular relates to a system and method for drying domestic garbage by utilizing waste heat from flue gas of a coal-fired boiler. Background Art

[0002] Compared with landfill, incineration, biological fermentation and other disposal methods, pyrolysis gasification can transform domestic waste, a complex, changeable and unstable solid renewable energy, into high-quality combustible gas, but its high water content restricts the implementation of the gasification process. Under the new power structure of low-carbon power generation and flexible peak-shaving of coal-fired power units, coal-fired boilers urgently need to be blended with renewable energy such as green hydrogen / green ammonia and biomass for deep peak-shaving and carbon reduction. Using domestic waste to prepare green hydrogen and then assist coal-fired boilers in efficient power generation has become a new trend in the industry.

[0003] Coal-fired boilers generate a large amount of flue gas waste heat during operation, which is often not fully utilized, resulting in energy waste.

[0004] To this end, the present invention proposes a system and method for drying domestic garbage using waste heat from flue gas of a coal-fired boiler. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art and provides a system and method for drying domestic waste using waste heat from flue gas of a coal-fired boiler.

[0006] One aspect of the present invention provides a system for drying domestic waste using waste heat from flue gas from a coal-fired boiler, comprising a coal-fired boiler system and a domestic waste drying system;

[0007] The coal-fired boiler system comprises a boiler body, a denitration device, an air preheater, a dust removal device, an induced draft fan and a desulfurization device connected in sequence;

[0008] The domestic waste drying system comprises a waste rotary drying device, the inlet of the waste rotary drying device is connected to the tail flue of the air preheater, and the outlet of the waste rotary drying device is connected to the front flue of the induced draft fan; wherein,

[0009] The waste heat of the flue gas drawn out from the tail flue of the air preheater is used to dry the wet domestic garbage in the garbage rotary drying device. The waste flue gas after heat exchange carries the garbage water vapor and enters the desulfurization device for purification under the traction of the induced draft fan.

[0010] Optionally, the garbage rotary drying device operates under negative pressure conditions to prevent odorous smoke from escaping.

[0011] Optionally, the domestic waste drying system further comprises a dry waste storage, which is connected to the outlet of the waste rotary drying device and is used for storing the dried domestic waste.

[0012] Optionally, the domestic waste drying system further includes a waste lifting device and a wet waste storage;

[0013] The inlet of the waste lifting device is connected to the wet waste storage, and the outlet of the waste lifting device is connected to the inlet of the waste rotary drying device.

[0014] Optionally, the coal-fired boiler system further includes a chimney, and the chimney is connected to the desulfurization device.

[0015] Optionally, the waste rotary drying device includes a segmented variable-diameter drum assembly;

[0016] The segmented variable-diameter drum assembly includes a front cylindrical section and a rear tapered section connected to the front cylindrical section; wherein,

[0017] The inner diameter of the front cylindrical section is 1.2 to 1.5 times the diameter of the inlet end of the rear tapered section.

[0018] Optionally, the waste rotary drying device further includes an anti-corrosion layer, and the anti-corrosion layer is provided on the inner side walls of the front cylindrical section and the rear tapered section.

[0019] Optionally, the anti-corrosion layer is made of an Al2O3-TiO2 composite ceramic layer.

[0020] Optionally, the waste rotary drying device further includes a variable-frequency speed regulation drive structure;

[0021] The variable-frequency speed regulation drive structure is used to dynamically adjust the rotation speed range of the segmented variable-diameter drum assembly to be 0.5 r / min to 2.5 r / min;

[0022] The variable-frequency speed regulation drive structure is also used to control the stepless regulation of the residence time of domestic waste within the range of 30 minutes to 90 minutes.

[0023] On the other hand, the present invention provides a method for drying domestic waste using the waste heat of coal-fired boiler flue gas. Using the system for drying domestic waste using the waste heat of coal-fired boiler flue gas described above, the method includes:

[0024] Using the waste heat of the waste flue gas led out from the tail flue of the air preheater to dry the wet domestic waste in the waste rotary drying device;

[0025] The waste flue gas carrying waste water vapor after heat exchange enters the desulfurization device under the traction of the induced draft fan for purification treatment.

[0026] The present invention provides a system and method for drying domestic garbage using the waste heat of flue gas from a coal-fired boiler. In the system, the inlet of a garbage rotary drying device is connected to the flue at the tail of an air preheater, and the outlet of the garbage rotary drying device is connected to the flue in front of an induced draft fan. The waste heat of the waste flue gas drawn out from the tail of the air preheater is used to dry the wet domestic garbage. The waste flue gas after heat exchange carries the water vapor of the garbage and enters the desulfurization device for purification under the traction of the induced draft fan. The system couples the drying process of domestic garbage with the coal-fired boiler. On the one hand, it can improve the recycling of waste heat from the flue gas of the coal-fired boiler and reduce energy waste; on the other hand, it can realize the drying and disposal of domestic garbage, and utilize the pressure difference between different devices of the coal-fired boiler to make the garbage rotary drying device operate under negative pressure conditions to avoid leakage of garbage odor. With the help of the tail gas purification system of the coal-fired boiler, the system can realize efficient coordinated disposal of the tail gas from garbage drying. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic structural diagram of a system for drying domestic waste using waste heat from flue gas of a coal-fired boiler according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0029] like Figure 1 As shown, one aspect of the present invention provides a system for drying domestic waste using waste heat from flue gas from a coal-fired boiler, comprising a coal-fired boiler system and a domestic waste drying system.

[0030] The coal-fired boiler system comprises a boiler body 1, a denitration device 2, an air preheater 3, a dust removal device 4, an induced draft fan 5, a desulfurization device 6 and a chimney 7 which are connected in sequence.

[0031] The domestic waste drying system includes a waste rotary drying device 8 , the inlet of the waste rotary drying device 8 is connected to the tail flue of the air preheater 3 , and the outlet of the waste rotary drying device 8 is connected to the front flue of the induced draft fan 5 .

[0032] Among them, a stream of waste flue gas is drawn out from the tail flue of the air preheater 3 and enters the garbage rotary drying device 8 to use the residual heat of the waste flue gas to dry the wet domestic garbage in the rotary drying device 8. The waste flue gas after heat exchange carries the garbage water vapor and enters the desulfurization device 6 for purification treatment under the traction of the induced draft fan 5, and is discharged through the chimney 7.

[0033] Specifically, during the normal operation of the coal-fired boiler in the power plant, the hot flue gas at the tail of the boiler body 1 first enters the denitrification device 2 under the traction of the induced draft fan 5, and heat is exchanged at the air preheater 3. At this time, the flue gas temperature drops from about 310°C at the inlet to about 140°C at the outlet. After heat exchange, the flue gas first enters the dust removal device 4 to capture and remove particulate matter, then enters the desulfurization device 6 for spray desulfurization, and finally enters the chimney 7 to be discharged into the atmosphere. The heat source for drying domestic garbage comes from the waste flue gas (about 140°C) at the outlet of the air preheater 3. A bypass flue gas is drawn out from the flue at the tail of the air preheater 3, and it passes through the garbage rotary drying device 8 to achieve the drying treatment of wet domestic garbage. The waste flue gas after heat exchange carries the garbage water vapor and enters the desulfurization device 6 under the traction of the induced draft fan 5 to achieve the purification treatment of the waste flue gas and garbage water vapor, and finally the tail gas is discharged into the chimney 7.

[0034] The system of the present invention utilizes the waste heat of flue gas from a coal-fired boiler to dry domestic waste. The system couples the drying process of domestic waste with the coal-fired boiler. On the one hand, it can improve the recycling of waste heat from flue gas from the coal-fired boiler and reduce energy waste. On the other hand, it can realize the drying and disposal of domestic waste. The pressure difference between different devices of the coal-fired boiler is utilized to make the waste rotary drying device operate under negative pressure conditions to avoid leakage of garbage odor. With the help of the tail gas purification system of the coal-fired boiler, the system can realize the efficient coordinated disposal of the tail gas from garbage drying.

[0035] Exemplarily, the garbage rotary drying device 8 operates under negative pressure conditions to prevent odorous smoke from escaping.

[0036] Specifically, the negative pressure at the outlet of the air preheater 3 is about -2000Pa~-3000Pa, and the negative pressure at the inlet of the induced draft fan 5 is about -2500Pa~-3500Pa. There is a pressure difference of about 500Pa~1000Pa between the two, which enables the garbage rotary drying device 8 to operate under negative pressure conditions without emitting odorous smoke.

[0037] In this embodiment, the pressure difference between the air preheater of the coal-fired boiler and the induced draft fan is utilized to make the garbage rotary drying device operate under negative pressure conditions to avoid leakage of garbage odor.

[0038] For example, Figure 1 As shown, the domestic waste drying system further includes a dry waste storage 9, which is connected to the outlet of the waste rotary drying device 8 and is used for storing the dried domestic waste.

[0039] For example, Figure 1 As shown, the domestic waste drying system further comprises a waste lifting and transporting device 10 and a wet waste storage 11. The inlet of the waste lifting and transporting device 10 is connected to the wet waste storage 11, and the outlet of the waste lifting and transporting device 10 is connected to the inlet of the waste rotary drying device 8.

[0040] Specifically, domestic waste is first collected and transported to a waste recycling station. After preliminary sorting, compression, dehydration, and shaping at the waste recycling station, it is finally transported to a coal-fired power plant. The domestic waste transported to the power plant is first stored in the wet waste storage bin 11, and then enters the waste rotary drying device 8 through the transportation and waste lifting device 10 for drying operation. At this time, the moisture content of the waste can finally be reduced to about 10%. The dried domestic waste is transported to the dry waste storage bin 9 for storage and standby.

[0041] Exemplarily, the waste rotary drying device 8 includes a segmented variable-diameter drum assembly; the segmented variable-diameter drum assembly includes a front cylindrical section and a rear tapered cone section connected to the front cylindrical section; wherein, the inner diameter of the front cylindrical section is 1.2 to 1.5 times the diameter of the inlet end of the rear tapered cone section.

[0042] Exemplarily, the waste rotary drying device 8 further includes an anti-corrosion layer, and the anti-corrosion layer is provided on the inner side walls of the front cylindrical section and the rear tapered cone section. The anti-corrosion layer can prevent the corrosion of the inner wall of the segmented variable-diameter drum assembly by the leachate of the waste.

[0043] Preferably, in this embodiment, the anti-corrosion layer adopts an Al2O3-TiO2 composite ceramic layer. The Al2O3-TiO2 composite ceramic layer can withstand Cl - and SO4 2- corrosion.

[0044] Exemplarily, the waste rotary drying device further includes a variable-frequency speed-regulating drive structure;

[0045] The variable-frequency speed-regulating drive structure is used to dynamically adjust the rotation speed of the segmented variable-diameter drum assembly in the range of 0.5 r / min to 2.5 r / min according to the initial moisture content of the waste (20%-50%). The variable-frequency speed-regulating drive structure is also used to control the residence time of the domestic waste in a stepless regulation range of 30 minutes to 90 minutes.

[0046] The waste rotary drying device further includes a spiral deflector arranged along the axial direction of the drum, which pushes the waste towards the outlet and forms an axial eddy current to extend the residence time of the hot flue gas.

[0047] Another aspect of the present invention provides a method S100 for drying domestic waste by using the waste heat of the flue gas of a coal-fired boiler. The system for drying domestic waste by using the waste heat of the flue gas of a coal-fired boiler described above is adopted. The structural features of the system for drying domestic waste by using the waste heat of the flue gas of a coal-fired boiler have been described in detail above and will not be repeated here.

[0048] The method S100 includes:

[0049] S110, utilizing the waste heat of the waste flue gas drawn out from the tail flue of the air preheater 3 to dry the wet domestic garbage in the garbage rotary drying device 8.

[0050] S120, the waste flue gas after heat exchange, carrying garbage water vapor, enters the desulfurization device 6 under the traction of the induced draft fan 5 for purification, and is finally discharged through the chimney 7.

[0051] The present invention provides a method for drying domestic waste by utilizing the waste heat of flue gas from a coal-fired boiler. The method couples the drying process of domestic waste with the coal-fired boiler. On the one hand, it can improve the recycling of waste heat from flue gas from the coal-fired boiler and reduce energy waste. On the other hand, it can achieve the drying and disposal of domestic waste. The pressure difference between different devices of the coal-fired boiler is utilized to enable the garbage rotary drying device to operate under negative pressure conditions to avoid leakage of garbage odor. The method can achieve efficient coordinated disposal of waste drying tail gas by using the tail gas purification system of the coal-fired boiler.

[0052] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A system for drying domestic waste by using the waste heat of the flue gas of a coal-fired boiler, characterized in that, Including coal-fired boiler system and domestic waste drying system; The coal-fired boiler system comprises a boiler body, a denitration device, an air preheater, a dust removal device, an induced draft fan and a desulfurization device connected in sequence; The domestic waste drying system comprises a waste rotary drying device, the inlet of the waste rotary drying device is connected to the tail flue of the air preheater, and the outlet of the waste rotary drying device is connected to the front flue of the induced draft fan; wherein, The waste heat of the flue gas drawn out from the tail flue of the air preheater is used to dry the wet domestic garbage in the garbage rotary drying device. The waste flue gas after heat exchange carries the garbage water vapor and enters the desulfurization device for purification under the traction of the induced draft fan.

2. The system according to claim 1, wherein The garbage rotary drying device operates under negative pressure conditions to prevent odorous smoke from escaping.

3. The system according to claim 1, wherein The domestic waste drying system further comprises a dry waste storehouse, which is connected to the outlet of the waste rotary drying device and is used for storing the dried domestic waste.

4. The system according to any one of claims 1 to 3, characterized in that The domestic waste drying system also includes a waste lifting and transporting device and a wet waste storage; The inlet of the garbage lifting and transporting device is connected to the wet garbage storehouse, and the outlet of the garbage lifting and transporting device is connected to the inlet of the garbage rotary drying device.

5. The system according to any one of claims 1 to 3, characterized in that, The coal-fired boiler system further comprises a chimney, and the chimney is connected to the desulfurization device.

6. The system according to any one of claims 1 to 3, characterized in that, The garbage rotary drying device comprises a segmented variable diameter roller assembly; The segmented variable diameter roller assembly comprises a front cylindrical section and a rear tapered conical section connected to the front cylindrical section; wherein, The inner diameter of the front cylindrical section is 1.2 to 1.5 times the diameter of the inlet end of the rear tapered conical section.

7. The system according to claim 6, characterized in that, The garbage rotary drying device also includes an anti-corrosion layer, which is arranged on the inner side walls of the front cylindrical section and the rear tapered conical section.

8. The system according to claim 7, wherein The anti-corrosion layer is an Al2O3-TiO2 composite ceramic layer.

9. The system according to claim 6, wherein The garbage rotary drying device also includes a variable frequency speed regulation drive structure; The variable frequency speed regulation drive structure is used to dynamically adjust the speed range of the segmented variable diameter roller assembly to 0.5r / min to 2.5r / min; The variable frequency speed regulation drive structure is also used to control the residence time of domestic waste to be steplessly regulated within a range of 30 minutes to 90 minutes.

10. A method for drying domestic waste by using the waste heat of the flue gas of a coal-fired boiler, characterized in that, The system for drying domestic waste using waste heat from flue gas of a coal-fired boiler as claimed in any one of claims 1 to 9 comprises: The wet domestic garbage in the garbage rotary drying device is dried by utilizing the waste heat of the waste flue gas drawn out from the tail flue of the air preheater; The waste flue gas after heat exchange carries garbage water vapor and enters the desulfurization device for purification under the traction of the induced draft fan.

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