A system and method for co-processing organic waste in cement kilns

Abstract

The present invention discloses a system and treatment method for the coordinated disposal of organic waste in a cement kiln. The treatment system includes a multiphase precombustion furnace and a material distribution device connected to the slag outlet of the multiphase precombustion furnace; the outlet of the material distribution device is respectively connected to a decomposition furnace and an ash cooling system; the ash cooling system includes a roller crusher, an ash grate cooler arranged at the outlet of the roller crusher, a tail roller crusher arranged at the outlet of the ash grate cooler, a blower for providing cooling air to the ash grate cooler, and an induced draft fan connected to the gas outlet of the ash grate cooler; the air inlet of the multiphase precombustion furnace is respectively connected to a tertiary air branch pipe and an induced draft fan. The present invention is adaptable to various real-life situations such as a wide variety of organic wastes, complex sources, large fluctuations in composition, and large differences in physical and chemical composition, and does not affect the stable operation of the cement clinker burning system.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste disposal, and in particular relates to a system and a method for co-disposing of organic waste in a cement kiln. Background Art

[0002] Chinese patent application CN102607044A discloses an incineration method for disposing of multi-variety, multi-phase wastes, belonging to the field of waste treatment methods, including passing the waste to be incinerated from top to bottom through the incineration device in an incineration device, and at the same time igniting and burning the waste to be incinerated by high-temperature wind passing through the incineration device from top to bottom, and carrying the incineration products out of the incineration device; the waste entering the incineration device is stopped at different height positions of the incineration device for incineration, and is controllably incinerated at each height position for a specified time before exiting the incineration device. This invention is an incineration method that can simultaneously dispose of three or more types of multi-variety, multi-phase wastes (industrial waste residue, waste liquid, municipal solid waste, sewage sludge) and can complete integrated disposal.

[0003] The combustion air of the pre-treatment equipment of this type of technology is generally provided by tertiary air. However, the temperature of tertiary air is relatively high. When the amount and calorific value of the organic waste being treated changes, the temperature of the pre-treatment equipment will also fluctuate, and the temperature of the flue gas entering the decomposition furnace will also fluctuate, affecting the stable operation of the cement kiln clinker burning system. In order to control the temperature, the method of adding combustibles (such as coal powder) and non-combustibles (such as raw materials) is generally adopted. This method has the problems of slow adjustment speed response, low control accuracy, and occupies the volume of the pre-treatment equipment. In addition, when the ash content of the organic waste is high and the elements that affect the quality of the clinker (such as P, Cl, heavy metal elements, etc.) are high, the traditional high-temperature pre-treatment equipment will directly send the ash into the decomposition furnace, which will affect the quality of the clinker, and then there will be a problem of insufficient disposal of organic waste. Summary of the Invention

[0004] Purpose of the Invention: To address the problems of the prior art, the present invention provides a system and method for the co-disposal of organic waste in a cement kiln. The system of the present invention addresses the issue of the stable operation of the cement firing system and the quality of the clinker affected by the co-disposal of large amounts of organic waste in a cement kiln. By providing a multi-phase pre-combustion furnace, the residence time of the waste and the temperature of the material entering the decomposition furnace can be controlled. Furthermore, by improving the ash cooling system and introducing cooling air from the cooling system into the pre-combustion furnace, supplemented by a burner, the combustion temperature within the multi-phase pre-combustion furnace can be controlled.

[0005] Technical solution: The system for co-disposal of organic waste in a cement kiln described in the present invention includes a multi-phase precombustion furnace and a material distribution device connected to the slag outlet of the multi-phase precombustion furnace; the outlet of the material distribution device is respectively connected to the decomposition furnace and the ash cooling system; the ash cooling system includes a roller crusher, an ash grate cooler arranged at the outlet of the roller crusher, a tail roller crusher arranged at the outlet of the ash grate cooler, a blower for providing cooling air to the ash grate cooler, and an induced draft fan connected to the gas outlet of the ash grate cooler; the air inlet of the multi-phase precombustion furnace is respectively connected to the tertiary air branch pipe and the induced draft fan.

[0006] As a preferred embodiment of the present invention, the gas outlet of the induced draft fan is respectively provided with a first residual air branch pipe and a second residual air branch pipe; the gas outlet of the first residual air branch pipe is connected to the air inlet of the multi-phase pre-combustion furnace.

[0007] As a preferred embodiment of the present invention, a first air volume regulating valve is provided on the first residual air branch pipe.

[0008] As a preferred embodiment of the present invention, a second air volume regulating valve is provided on the second residual air branch pipe.

[0009] As a preferred embodiment of the present invention, the second waste air branch pipe is connected to the waste heat power generation system.

[0010] As a preferred embodiment of the present invention, a third air volume regulating valve is provided on the tertiary air branch pipe.

[0011] As a preferred embodiment of the present invention, a first valve is provided between the material distribution device and the ash cooling system.

[0012] As a preferred embodiment of the present invention, a second valve is provided between the material distribution device and the decomposition furnace.

[0013] As a preferred embodiment of the present invention, the tertiary air branch pipe is connected to the tertiary air duct of the decomposition furnace.

[0014] The method for waste treatment using the above-mentioned cement kiln co-processing system for organic waste comprises the following steps:

[0015] (S1) waste is fed into a multiphase precombustion furnace, and the amount of air fed into the multiphase precombustion furnace is adjusted by air volume control valves of the tertiary air branch pipe and the first residual air branch pipe. At the same time, the operating temperature of the multiphase waste precombustion furnace is controlled according to the air volume ratio of the tertiary air branch pipe and the first residual air branch pipe and the injection amount of the auxiliary fuel;

[0016] (S2) the ash after being processed in the multi-phase pre-combustion furnace is sent to the decomposition furnace for processing or to the ash cooling system through the material separation device;

[0017] (S3) The ash fed into the ash cooling system is first crushed by a roller crusher and then enters an ash grate cooler, where it is cooled by cooling air sent by a blower. The cooled ash is crushed to a particle size of 20-30 mm by a tail roller crusher before being discharged. The residual air generated by the ash grate cooler is extracted by an induced draft fan.

[0018] (S4) The outlet of the induced draft fan is divided into two routes, one of which is connected to the combustion air inlet of the multi-phase pre-combustion furnace through the first residual air branch pipe, and the other is connected to the waste heat power generation system. The air volume fed into the multi-phase pre-combustion furnace and the waste heat power generation system is regulated by adjusting the air volume ratio of the first air volume regulating valve provided on the first residual air branch pipe and the second air volume regulating valve provided between the induced draft fan and the waste heat power generation system.

[0019] Beneficial effects: (1) The present invention adopts a multi-phase waste pre-combustion furnace to pre-treat organic waste, which is suitable for a variety of real situations such as a wide variety of organic wastes, complex sources, large fluctuations in composition, and large differences in physical and chemical composition, and does not affect the stable operation of the cement clinker burning system; (2) The present invention utilizes tertiary air and residual air of the ash cooling system as combustion air, which can not only reduce the auxiliary fuel consumption of the multi-phase waste pre-combustion furnace, but also control the amount and temperature of the combustion air entering the high-temperature pre-treatment system by adjusting the air volume and ratio of the tertiary air and the residual air, and at the same time coordinate with the burner injection amount adjustment to control the temperature in the high-temperature pre-treatment system. And maintain it within a certain temperature range, to minimize the negative impact of the unstable calorific value of organic waste on the cement kiln clinker burning system; (3) The present invention solves the problem that the cement kiln co-disposes of a large amount of organic waste, affecting the stable operation of the cement burning system and the stability of the clinker quality. By setting a multi-phase pre-combustion furnace, the residence time of the waste can be controlled and the temperature of the material entering the decomposition furnace can be controlled; (4) The present invention can flexibly adjust the direction of the waste ash by setting a material distribution device, reduce the influence of the ash composition on the quality of cement clinker, and can greatly increase the amount of co-disposed organic waste without affecting the stable operation of the cement clinker burning system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the organic waste treatment system of the present invention;

[0021] Figure 2 The material and heat balance calculation results of the multiphase precombustion furnace of the present invention for treating 250t / d of organic waste;

[0022] Figure 3 This is the material and heat balance calculation result of the ash grate cooler of the present invention. DETAILED DESCRIPTION

[0023] Example 1: Figure 1 As shown, the system for co-disposal of organic waste in a cement kiln of the present invention includes a multiphase precombustion furnace 1 and a distribution device 2 connected to the solid outlet of the multiphase precombustion furnace 1, the outlet of the distribution device 2 is respectively connected to the decomposition furnace 3 and the ash cooling system 4, a first valve 201 is provided between the distribution device 2 and the ash cooling system 4, and a second valve 202 is provided between the distribution device 2 and the decomposition furnace 3.

[0024] The front end of the multiphase pre-combustion furnace 1 of the present invention is provided with an inlet and an auxiliary burner to meet the requirements of waste feeding in various phases (solid, semi-solid, liquid). The specific structure can be found in Chinese Patent 2022101582432. In this embodiment, the main body of the multiphase pre-combustion furnace 1 adopts a rotary kiln structure with a variable speed, which is inclined at 2° to 5° with the horizontal plane. By adjusting the speed of the rotary kiln, the amount of auxiliary fuel sprayed, and the intake air volume and intake air temperature of the combustion air, the residence time and combustion state of the waste in the multiphase pre-combustion furnace 1 are controlled to ensure the disposal effect. The rear end of the multiphase pre-combustion furnace 1 is an ash outlet, and the outlet is connected to the material distribution device 2.

[0025] The material distribution device 2 is divided into two channels, each of which is provided with a first valve 201 and a second valve 202 (the first valve 201 is provided between the material distribution device 2 and the ash cooling system, and the second valve 202 is provided between the material distribution device 2 and the decomposition furnace). One of the two channels of the material distribution device 2 is connected to the decomposition furnace 3, and the other is connected to the slag inlet of the ash cooling system 4. The destination of the residue of the material distribution device 2 is determined according to the amount and composition of the residue generated after the organic waste is treated in the multi-phase pre-combustion furnace 1, and the impact on the stable operation of the cement clinker burning system: when the impact of the residue directly entering the decomposition furnace 3 on the stable operation of the cement clinker burning system is acceptable, the material distribution device 2 sends the residue to the decomposition furnace 3; otherwise, the material distribution device 2 sends the residue to the ash cooling system 4.

[0026] The ash cooling system 4 includes a roller crusher 401, an ash grate cooler 402 located at the outlet of the roller crusher 401, a tail roller crusher 403 located at the outlet of the ash grate cooler 402, a blower 404 for providing cooling air to the ash grate cooler 402, and an induced draft fan 405 connected to the gas outlet of the ash grate cooler 402. The blower 404 can be a single blower or a combination of multiple blowers depending on the scale of the ash cooling. The ash grate cooler 402 has a similar structure to the cement kiln clinker grate cooler, with the roller crusher 401 located at the front of the ash inlet and the tail roller crusher 403 located at the ash outlet. The blower 404 is used to provide the cooling air required by the ash grate cooler 402, and the induced draft fan 405 is used to extract the residual air generated by the ash-specific grate cooler.

[0027] The outlet of induced draft fan 405 is equipped with two branch pipes: a first residual air branch pipe 406 and a second residual air branch pipe 407. The gas outlet of first residual air branch pipe 406 is connected to the air inlet of multi-phase pre-combustion furnace 1, while the second residual air branch pipe 407 is connected to the waste heat power generation system. The residual air is delivered to multi-phase pre-combustion furnace 1 and the waste heat power generation system through these two branch pipes. A first air volume regulating valve 408 is installed on the first residual air branch pipe 406, and a second air volume regulating valve 409 is installed on the second residual air branch pipe 407 to adjust the air volume of the two branch pipes.

[0028] The air inlet of the multiphase precombustion furnace 1 is connected to the tertiary air branch pipe 101 and the induced draft fan 405 respectively. The tertiary air branch pipe 101 is connected to the tertiary air duct 301 arranged on the decomposition furnace 3. The air at the combustion air inlet of the multiphase precombustion furnace 1 comes partly from the tertiary air branch pipe 101 and partly from the ash cooling system 4. A third air volume regulating valve 102 is provided on the tertiary air branch pipe 101. The present invention controls the amount and temperature of combustion air entering the multiphase precombustion furnace 1 by adjusting the first air volume regulating valve 408 on the first residual air branch pipe 406, the second air volume regulating valve 409 on the second residual air branch pipe 407 and the third air volume regulating valve 102.

[0029] The specific connection method between the induced draft fan 405 and the cement plant waste heat power generation system can be that the second waste air branch pipe 407 is connected to the kiln tail exhaust gas pipeline in front of the SP furnace, or it can be connected to the kiln head exhaust gas pipeline in front of the AQC furnace.

[0030] Example 2: A method for treating organic waste using the cement kiln co-treatment system of Example 1, comprising the following steps:

[0031] (S1) Waste is fed into the multiphase precombustion furnace 1. The air volume supplied to the multiphase precombustion furnace 1 is regulated by the air volume control valves of the tertiary air branch pipe 101 and the first residual air branch pipe 406. At the same time, the operating temperature of the multiphase waste precombustion furnace is controlled according to the air volume ratio of the tertiary air branch pipe 101 and the first residual air branch pipe 406 and the injection amount of the auxiliary fuel.

[0032] (S2) The ash after being processed by the multi-phase pre-combustion furnace 1 is sent to the decomposition furnace 3 for processing through the material distribution device 2 or sent to the ash cooling system 4;

[0033] (S3) The ash fed into the ash cooling system 4 is first crushed by the roller crusher 401 and then enters the ash grate cooler 402. Inside the ash grate cooler 402, it is cooled by the cooling air sent by the blower 404. The cooled ash is crushed by the tail roller crusher to a particle size of 20 to 30 mm (meeting the principle batching requirements) and then discharged. The residual air generated by the ash grate cooler 402 is extracted by the induced draft fan 405.

[0034] (S4) The outlet of the induced draft fan 405 is divided into two routes, one of which is connected to the combustion air inlet of the multi-phase pre-combustion furnace 1 through the first residual air branch pipe 406, and the other is connected to the waste heat power generation system. The air volume fed into the multi-phase pre-combustion furnace 1 and the waste heat power generation system is regulated by adjusting the air volume ratio of the first air volume regulating valve 408 provided on the first residual air branch pipe 406 and the second air volume regulating valve 409 provided between the induced draft fan 405 and the waste heat power generation system.

[0035] Example 3: The material and heat balance of the present invention is calculated as follows:

[0036] (1) Material and heat balance calculation of multiphase precombustion furnace

[0037] The calculation uses the cement production line's tertiary air and all residual air from the ash cooling system as the combustion air and heat sources. The tertiary air supply ratio is adjusted to ensure that the rotary kiln does not require supplemental combustion. Low calorific value (1000 kcal / kg) organic waste was selected as the research object, and its composition is shown in Table 1.

[0038] Table 1 Elemental composition of low calorific value (1000 kcal / kg) organic waste materials co-processed in cement kilns

[0039] type C H O N S Cl Water ASH F total waste 10.00％ 2.20％ 4.30％ 0.00％ 0.00％ 0.00％ 40.00％ 43.50％ 0.00％ 100％

[0040] The design parameters are selected as follows:

[0041] ①The outlet flue gas temperature is 1000℃.

[0042] ②The excess air coefficient is 1.17 and the air leakage ratio is 10%.

[0043] ③ The multiphase pre-combustion furnace is a rotary kiln with an outer diameter of 4.0m, a length of 15m and an insulation layer thickness of 300mm.

[0044] ④The ambient temperature is 20℃ and the local atmospheric pressure is 101.325kpa.

[0045] ⑤ The tertiary air comes from the 5000t / d clinker production line, and the temperature is 900℃.

[0046] ⑥The residual air temperature of the ash cooling system is 320℃.

[0047] The scale of organic waste co-processing in a single cement line is 75,000 tons / year (250t / d). The simulation results are as follows: Figure 2 The composition of the flue gas at the outlet of the multiphase pre-combustion furnace is shown in the following table.

[0048] Table 2 Composition of flue gas at the outlet of the multiphase pre-combustion furnace for the co-treatment of 250t / d organic waste

[0049] Element <![CDATA[O2]]> <![CDATA[CO2]]> <![CDATA[N2]]> CxDJ <![CDATA[H2O (vapor)]]> total <![CDATA[Concentration Nm 3 / h]]> 1871 1254 14109 829 6840 24904 Volume fraction 6.3％ 5.9％ 56.8％ 2.4％ 28.6％ 100％

[0050] According to the material and heat balance calculation results, we can know that:

[0051] ①The flue gas inlet velocity is 0.14m / s and the outlet velocity is 3.60m / s.

[0052] ②The combustion rate of organic matter in organic waste is 64.48%.

[0053] ③The proportion of tertiary air intake is 13%.

[0054] (2) Material and heat balance calculation of ash cooling system

[0055] The calculation uses the ash produced by the multiphase pre-combustion furnace as the research object, and the design parameters are selected as follows:

[0056] ①The ash cooling temperature is 100℃.

[0057] ②The overall dimensions of the equipment are 6.0m in length, 2.0m in width and 3.0m in height.

[0058] ③ All the remaining air is sent to the multi-phase pre-combustion furnace.

[0059] The simulation results are as follows Figure 3 As shown. According to the material and heat balance calculation results, we can know that:

[0060] The cooling air volume of the ash cooling system is about 9570.17Nm 3 / h, the residual air volume is 9570.17Nm 3 / h, temperature 320℃.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents, and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for co-processing organic waste in a cement kiln, characterized in that: The invention comprises a multiphase pre-combustion furnace (1) and a material distribution device (2) connected to the slag outlet of the multiphase pre-combustion furnace (1); the outlet of the material distribution device (2) is respectively connected to the decomposition furnace (3) and the ash cooling system (4); the destination of the residue of the material distribution device (2) is determined according to the amount and composition of the residue generated after the organic waste is disposed of by the multiphase pre-combustion furnace (1) and the influence on the stable operation of the cement clinker burning system: when the residue directly enters the decomposition furnace (3) and the influence on the stable operation of the cement clinker burning system is acceptable, the material distribution device (2) sends the residue to the decomposition furnace (3); otherwise, the material distribution device (2) ) sends the residue into an ash cooling system (4); the ash cooling system (4) comprises a roller crusher (401), an ash grate cooler (402) arranged at the outlet of the roller crusher (401), a tail roller crusher (403) arranged at the outlet of the ash grate cooler (402), a blower (404) for providing cooling air to the ash grate cooler (402), and an induced draft fan (405) connected to the gas outlet of the ash grate cooler (402); the air inlet of the multi-phase pre-combustion furnace (1) is connected to the tertiary air branch pipe (101) and the induced draft fan (405), respectively.

2. The system for co-processing organic waste in cement kilns according to claim 1, characterized in that: The gas outlet of the induced draft fan (405) is respectively provided with a first residual air branch pipe (406) and a second residual air branch pipe (407); the gas outlet of the first residual air branch pipe (406) is connected to the air inlet of the multi-phase pre-combustion furnace (1).

3. The system for co-processing organic waste in cement kilns according to claim 2, characterized in that: The first residual air branch pipe (406) is provided with a first air volume regulating valve (408).

4. The system for co-processing organic waste in cement kilns according to claim 3, characterized in that: The second residual air branch pipe (407) is provided with a second air volume regulating valve (409).

5. The system for co-processing organic waste in cement kilns according to claim 4, characterized in that: The second residual air branch pipe (407) is connected to the waste heat power generation system.

6. The system for co-processing organic waste in cement kilns according to claim 1, characterized in that: The tertiary air branch pipe (101) is provided with a third air volume regulating valve (102).

7. The system for co-processing organic waste in cement kilns according to claim 1, characterized in that: A first valve (201) is provided between the material distribution device (2) and the ash cooling system (4).

8. The system for co-processing organic waste in cement kilns according to claim 1, characterized in that: A second valve (202) is provided between the material distribution device (2) and the decomposition furnace (3).

9. The system for co-processing organic waste in cement kilns according to claim 1, characterized in that: The tertiary air branch pipe (101) is in communication with the tertiary air pipe (301) of the decomposition furnace (3).

10. A method for waste treatment using the system for co-processing organic waste in a cement kiln according to claim 1, characterized in that: The following steps are involved: (S1) Waste is fed into the multiphase precombustion furnace (1), and the air volume flow rate of the multiphase precombustion furnace (1) is adjusted by the air volume control valves of the tertiary air branch pipe (101) and the first residual air branch pipe (406), and the operating temperature of the multiphase precombustion furnace (1) is controlled according to the air volume ratio of the tertiary air branch pipe (101) and the first residual air branch pipe (406) and the injection amount of the auxiliary fuel; (S2) The ash after being processed in the multi-phase pre-combustion furnace (1) is sent to the decomposition furnace (3) for processing through the material distribution device (2) or sent to the ash cooling system (4); (S3) The ash fed into the ash cooling system (4) is first crushed by a roller crusher (401) and then enters an ash grate cooler (402). Inside the ash grate cooler (402), the ash is cooled by cooling air sent by a blower (404). The cooled ash is crushed to a particle size of 20 to 30 mm by a tail roller crusher and then discharged. The residual air generated by the ash grate cooler (402) is extracted by an induced draft fan (405); (S4) The outlet of the induced draft fan (405) is divided into two routes, one route is connected to the combustion air inlet of the multi-phase pre-combustion furnace (1) through the first residual air branch pipe (406), and the other route is connected to the waste heat power generation system. By adjusting the air volume ratio of the first air volume regulating valve (408) provided on the first residual air branch pipe (406) and the second air volume regulating valve (409) provided between the induced draft fan (405) and the waste heat power generation system, the air volume fed into the multi-phase pre-combustion furnace (1) and the waste heat power generation system is adjusted.

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