A rotary kiln incinerator capable of in-furnace desulfurization and a desulfurization method

Abstract

The application discloses a rotary kiln incinerator capable of in-furnace desulfurization, and relates to the technical field of solid waste rotary kiln combustion and desulfurization. The application mainly solves the problems of low in-furnace desulfurization efficiency and low desulfurizer utilization rate. A nozzle is arranged above a multi-channel burner at a kiln tail and extends into the furnace, so that the tail end of the nozzle is parallel to the center line of the burner. The desulfurizer is sprayed into the furnace through a guide plate by using a pneumatic conveying mode and is fully mixed with internal rotational flow air or central air of the multi-channel burner, so that the desulfurizer and flue gas are fully and uniformly contacted, and the problem that the desulfurizer and incineration flue gas are not fully contacted caused by the fact that the desulfurizer is mixed with solid waste and then sent into the furnace in the prior art is avoided. The desulfurization efficiency of the rotary kiln incinerator and the utilization rate of the desulfurizer can be greatly improved, so that the emission of sulfur oxides in flue gas is effectively reduced, the operation economy of the desulfurization system is improved, and the application prospect is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of boiler combustion adjustment, in particular to a rotary kiln incinerator capable of in-furnace desulfurization and a control system. BACKGROUND

[0002] With the rapid development of economy, more and more sludge and other solid wastes are generated in life and industrial production. In order to effectively reduce the pollution caused by solid waste to the environment and the harm to human health, it is necessary to harmless treatment. Among various solid waste treatment and disposal processes, compared with landfill and pyrolysis and other disposal methods, incineration can minimize the volume of solid waste, and can completely kill all bacteria and pathogens, and completely oxidize and decompose toxic and harmful organic matter. At the same time, it can also utilize the potential heat energy for heating and power generation, realize reduction, harmless and resourceful disposal, and become one of the current main development directions and research hotspots.

[0003] There are many types of solid waste incineration equipment, including multi-chamber incinerator, fluidized bed incinerator and rotary kiln incinerator. Among them, the rotary kiln incinerator is widely researched and applied due to its strong fuel adaptability, simple device and large amount of material treatment.

[0004] The fluidized bed benefits from its sufficient gas-solid mixing conditions, and can mix the desulfurizer with the fuel at the bottom of the furnace and input it, but in the rotary kiln furnace where the gas-solid mixing contact is insufficient, it cannot be applied.

[0005] In the rotary kiln incineration system, desulfurization is usually carried out by tail gas side desulfurization or by mixing solid waste with desulfurizer and adding it into the furnace, so as to reduce the concentration of sulfur dioxide in the exhaust gas.

[0006] Tail gas desulfurization occurs after combustion, which requires additional desulfurization devices, increasing the cost and land occupation of desulfurization.

[0007] In the existing rotary kiln desulfurization process, the desulfurizer is usually mixed with the solid waste and added into the furnace for incineration, including direct mixing or mixing and rolling into pellets. This method also faces the problem of insufficient mixing of desulfurizer and flue gas, resulting in low desulfurization efficiency and desulfurizer utilization rate.

[0008] In order to meet the emission limit value of flue gas, it is necessary to increase the input of desulfurizer or add a flue gas desulfurization device at the tail of the furnace, which is not economical. SUMMARY

[0009] The purpose of the present application is to solve the problems in the prior art, and to provide a rotary kiln incinerator and a desulfurization method capable of uniformly spraying desulfurizer into the rotary kiln furnace tube, effectively improving the contact performance of desulfurizer and flue gas.

[0010] To solve the above technical problems, the technical method adopted by the present application is: the present application discloses a rotary kiln incinerator capable of in-furnace desulfurization, comprising a rotary kiln cylinder, a kiln head mechanism arranged at the first end of the rotary kiln cylinder, and a feeding mechanism arranged at the tail end of the rotary kiln cylinder; characterized in that: the kiln head mechanism comprises a burner and a desulfurizing agent injection pipe arranged in front of the burner and used for spraying desulfurizing agent;

[0011] The burner comprises a flame injection port arranged at the center of the burner, a first flow air duct arranged around the flame injection port, and a second flow air duct arranged at the outer circle of the first flow air duct.

[0012] A pulverized coal air duct for spraying pulverized coal is arranged between the first flow air duct and the second flow air duct.

[0013] Further, the first flow air duct is an outer axial flow air duct, and air is sent out along the flame injection direction of the flame injection port;

[0014] The second flow air duct is an inner rotational flow air duct, and air is sent out in a spiral shape along the flame injection direction of the flame injection port.

[0015] Further, the desulfurizing agent injection port of the desulfurizing agent injection pipe is located directly in front of the flame injection port.

[0016] Further, the desulfurizing agent injection pipe is provided with a conical diffusion spray head at the tail end, the conical diffusion spray head is provided with a plurality of desulfurizing agent injection ports, and the desulfurizing agent injection ports are distributed in a ring shape around the conical diffusion spray head.

[0017] Further, the rotary kiln cylinder is arranged in an inclined manner, and the horizontal height of the first end of the rotary kiln cylinder is lower than the horizontal height of the tail end of the rotary kiln cylinder.

[0018] The present application also discloses a desulfurization method for a rotary kiln incinerator capable of in-furnace desulfurization, comprising the rotary kiln incinerator capable of in-furnace desulfurization according to any one of claims 1-5 and the following steps.

[0019] S1. When the rotary kiln incineration system is working, the desulfurizing agent injection pipe sprays raw lime or limestone as a desulfurizing agent above the flame injection port for desulfurization, the desulfurizing agent is contacted with and fully mixed with the outer axial flow air or the inner rotational flow air sprayed by the first flow air duct or the second flow air duct, so as to realize sufficient and uniform contact between the desulfurizing agent and the flue gas;

[0020] S2. The temperature of the rotary kiln and the residence time of the solid waste are controlled, and the desulfurization product is discharged from the discharge port together with the slag or from the flue gas outlet together with the flue gas.

[0021] Further, the maximum particle size of the raw lime or limestone desulfurizing agent is not more than 65 μm, the average particle size is 30-50 μm, and the content of CaO or CaCO3 in the desulfurizing agent is greater than 90%.

[0022] When the rotary kiln incineration system is working, the calcium-sulfur molar ratio in the cylinder is 2-3, the temperature in the rotary kiln is 800-1000 DEG C, and the residence time of solid waste in the rotary kiln is 30-60 minutes.

[0023] Further, the excess air coefficient in the rotary kiln is 1.2-2.

[0024] Beneficial effects:

[0025] 1. Compared with the prior art, the application provides a desulfurization nozzle arrangement mode and structure which can be applied to a rotary kiln, a nozzle is arranged above a multi-channel burner at the kiln tail for conveying a desulfurizing agent, and the nozzle is bent so that the end thereof is flush with the center line of the burner, a plurality of holes are arranged on the conical surface of the end of the nozzle for spraying the desulfurizing agent, the contact area of the desulfurizing agent and flue gas is increased, the desulfurizing agent is mixed with the flow air sprayed from the first flow air channel and the second flow air channel in the burner, part of the desulfurizing agent can be avoided from being captured by the inner wall of the furnace tube to reduce the utilization rate, the stability of the air channel of the burner is ensured, the desulfurization efficiency in the furnace is effectively improved on the basis of not damaging the original structure, and the gas-solid mixing condition of the desulfurizing agent powder and flue gas is effectively improved.

[0026] 2. The first flow air channel is an outer axial flow air channel, air is sent out along the flame jet direction of the flame jet port; the second flow air channel is an inner rotational flow air channel, air is sent out in a spiral shape along the flame jet direction of the flame jet port. The desulfurizing agent is rectified by the flow guide plate and then contacts the inner rotational flow air at the innermost side of the burner, so that the desulfurizing agent powder is uniformly distributed in the circumferential direction, the desulfurizing agent powder and the combustion flame are stably advanced in the furnace in the axial direction through the outermost outer axial flow air, and the problem that the desulfurizing agent powder is captured by the inner wall of the rotary kiln to reduce the utilization rate is effectively avoided, the coal powder channel promotes the combustion in the kiln by spraying coal powder to improve the reaction temperature, and the solid waste treatment efficiency and the desulfurization reaction efficiency are improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the rotary kiln incinerator with in-furnace desulfurization in the application;

[0028] Figure 2 It is a local enlarged schematic diagram of the kiln head mechanism in the application;

[0029] Figure 3 It is a schematic diagram of the specific structure of the first flow air channel and the first flow air channel in the application;

[0030] Figure 4 It is a schematic diagram of the air flow sprayed by the first flow air channel and the second flow air channel in the application. DETAILED DESCRIPTION

[0031] The application will be further described in detail in connection with the accompanying drawings and specific embodiments.

[0032] As Figures 1-4 shown, the present example is a rotary kiln incinerator capable of in-furnace desulfurization, which removes sulfur oxides by spraying limestone or quicklime desulfurizer into the cylinder.

[0033] As Figures 1-4 shown, the rotary kiln incinerator includes a kiln head mechanism 1, a slag outlet 2, a slag collecting device 3, a riding wheel 4, a refractory brick lining 5, a rotary kiln cylinder 6, a kiln tail cover 7, a feeding hopper 8, a material conveying belt 9, a flue gas outlet 10, a desulfurizer bin 14, and a fan 15. As Figure 2 shown, the kiln head mechanism of the rotary kiln incinerator system includes a burner 11 and a desulfurizer injection pipe 12 arranged above the burner and its end guide plate 13, wherein the burner mainly includes a first flow air duct 111, a pulverized coal air duct 112, and a second flow air duct 113.

[0034] The dashed line in the rotary kiln cylinder 6 represents the flow direction of flue gas and desulfurizer, and the solid line represents the flow direction of solid waste.

[0035] The desulfurization method of the rotary kiln incinerator based on in-furnace desulfurization in the present application is to spray quicklime or limestone as desulfurizer into the furnace through the injection pipe arranged above the kiln tail burner during the operation of the rotary kiln incineration system, control the rotary kiln temperature and the residence time of solid waste, and discharge the desulfurization products along with the slag from the discharge port or along with the flue gas from the flue gas outlet. During the process of injecting desulfurizer into the furnace pipe, the following parameters are required:

[0036] a). The maximum particle size of quicklime or limestone desulfurizer particles is not more than 65 μm, the average particle size is 30-50 μm, and the CaO or CaCO3 content in the desulfurizer is greater than 90%;

[0037] b). The calcium to sulfur ratio in the cylinder is maintained at 2-3 during the operation of the rotary kiln incineration system, the temperature in the furnace is 800-1000℃, and the residence time of solid waste in the cylinder is 30-60 minutes.

[0038] The desulfurization process mainly includes the following two reactions:

[0039] CaCO3→CaO+CO2(1)

[0040] CaO+SO2+0.5O2→CaSO4(2)

[0041] Reaction formula 1 is the calcination reaction of limestone, and reaction formula 2 is the sulfur dioxide absorption reaction.

[0042] Since the desulfurization reaction needs oxygen to participate, the excess air coefficient in the rotary kiln cylinder 6 needs to be controlled to be 1.2-2, so as to ensure that the forward reaction of formula 2 is carried out and the incineration product has a low ignition loss. When the oxygen content in the flue gas at the kiln head is low, the oxygen concentration needs to be increased by increasing the combustion air volume.

[0043] The average temperature in the rotary kiln cylinder 6 should be kept at 800-1000℃. The temperature also affects the desulfurization efficiency in the furnace. If the temperature is too low, the generation of CaO in formula 1 will be reduced, and if the temperature is too high, the generated CaSO4 will be decomposed to release SO2, affecting the desulfurization effect, so the incineration temperature in the reaction device needs to be strictly controlled. According to different rotary kiln incinerator devices, the temperature in the cylinder can be adjusted by adjusting the burner parameters.

[0044] The application can achieve ultra-low SO2 emission by controlling the input desulfurizer calcium-sulfur molar ratio in the range of 2-3, adjusting the rotary kiln cylinder speed and inclination to control the material residence time in 30-60 minutes, and keeping the excess air coefficient in the cylinder at 1.2-2 at the incineration temperature of 800-1000℃.

[0045] After high-temperature incineration at 800-1000℃, the S element in solid waste reacts to generate SO2 mixed in the flue gas, and the quicklime or limestone sprayed into the furnace tube generates CaO in the rotary kiln. CaO reacts with SO2 in the flue gas to generate CaSO4, which is discharged from the discharge port with the slag or from the flue gas outlet with the flue gas.

[0046] As shown in Figure 4 The first flow air duct 111 is an outer axial flow air duct, which sprays the outer axial flow 1110 to send air along the direction of the flame jet; the second flow air duct 113 is an inner rotational flow air duct, which sprays the inner rotational flow 1130 to send air in a spiral shape along the direction of the flame jet. The desulfurizer is rectified by the guide plate and contacts the inner rotational flow 1130 at the innermost side of the burner 1, so that the desulfurizer powder is evenly distributed in the circumferential direction, and at the same time, the desulfurizer powder and the combustion flame are kept stable in the furnace along the axial direction by the outermost outer axial flow 1110, effectively avoiding the problem that the utilization rate is reduced due to the capture of the desulfurizer powder by the inner wall of the rotary kiln. The pulverized coal air duct 112 promotes the combustion in the kiln by spraying coal powder to increase the reaction temperature, which can improve the desulfurization reaction efficiency while improving the solid waste treatment efficiency.

[0047] Embodiment

[0048] As shown in Figure 1As shown, the embodiment provides a rotary kiln incinerator in-furnace desulfurization incineration method, comprising: when the rotary kiln furnace incineration system is working, through the desulfurizer injection pipe 12 arranged above the kiln tail burner, injecting raw lime or limestone into the furnace as a desulfurizer for desulfurization, so that the desulfurizer is fully mixed with the inner cyclone wind 113 of the burner 11 after being rectified by the guide plate 13, and the calcium-sulfur ratio in the furnace is maintained at 2-3.

[0049] The above technical solution is the core technical solution of the rotary kiln in-furnace desulfurization incineration system of the present application, so that the desulfurizer is in contact with the innermost inner cyclone wind of the burner after being rectified by the guide plate, thereby making the desulfurizer powder uniformly distributed in the circumferential direction, and at the same time, the desulfurizer powder and the combustion flame in the furnace are stably advanced in the axial direction by the outermost outer axial flow wind, and the problem of desulfurizer powder being captured by the inner wall of the rotary kiln to cause utilization rate to decrease is effectively avoided, the coal powder duct promotes the combustion in the kiln by spraying coal powder to improve the reaction temperature, and the solid waste treatment efficiency is improved while the desulfurization reaction efficiency is also improved. By such a device, the desulfurizer sprayed into the cylinder is fully mixed with the inner cyclone wind of the burner, avoiding the problems of low utilization rate of desulfurizer, too many devices for tail gas desulfurization, and inconvenient operation in the existing rotary kiln desulfurization technology;

[0050] At the same time, the desulfurizer is sprayed into the furnace by pneumatic conveying and fully mixed with the inner cyclone wind of the multi-channel burner, realizing full and uniform contact of the desulfurizer with the flue gas, avoiding the problem of insufficient contact of the desulfurizer with the incineration flue gas caused by mixing the desulfurizer with the solid waste and then feeding it into the furnace, and making up for the shortcomings of large occupied area, poor economy, low desulfurization efficiency and desulfurizer utilization rate in the prior art, effectively improving the operation economy of the rotary kiln desulfurization system, and ensuring that the rotary kiln incineration system realizes high desulfurization efficiency at a lower cost.

[0051] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A rotary kiln incinerator which is capable of in-furnace desulfurization, characterized by: The rotary kiln comprises a rotary kiln cylinder (6), a kiln head mechanism (1) arranged at the front end of the rotary kiln cylinder (6), and a feeding mechanism (8) arranged at the tail end of the rotary kiln cylinder (6); the kiln head mechanism (1) comprises a burner (11), a desulfurizing agent injection pipe (12) arranged in front of the burner (11) and passing through the kiln head mechanism (1) and a guide plate (13). The burner (11) comprises a flame injection port (110) arranged at the center of the burner (11), a first flow air channel (111) arranged around the flame injection port, and a second flow air channel (113) arranged at the outer ring of the first flow air channel (111). A pulverized coal air channel (112) for injecting pulverized coal is arranged between the first flow air channel (111) and the second flow air channel (113). The first flow air channel (111) is an outer axial flow air channel, and air is sent out along the direction of the flame injection port (110); the second flow air channel (113) is an inner spiral flow air channel, and air is sent out in a spiral shape along the direction of the flame injection port (110). The desulfurizing agent injection pipe (12) is arranged in front of the flame injection port (110). The desulfurizing agent is rectified by the guide plate (13) and contacts the inner spiral flow air (1130) at the innermost side of the burner (11), so that the desulfurizing agent powder is uniformly distributed in the circumferential direction, and the desulfurizing agent powder and the combustion flame are kept moving in the axial direction in the furnace through the outer axial flow air (1110) at the outermost side, thereby avoiding that the desulfurizing agent powder is captured by the inner wall of the rotary kiln.

2. The in-situ desulfurizable rotary kiln incinerator of claim 1, wherein: A conical diffusion nozzle is arranged at the tail end of the desulfurizing agent injection pipe (12), and a plurality of desulfurizing agent injection ports are arranged in the conical diffusion nozzle and are annularly distributed around the conical diffusion nozzle.

3. The in-situ desulfurizable rotary kiln incinerator of claim 1, wherein: The rotary kiln cylinder (6) is arranged in an inclined manner, and the horizontal height of the front end of the rotary kiln cylinder (6) is lower than the horizontal height of the tail end of the rotary kiln cylinder (6).

4. A method for desulfurization of a rotary kiln incinerator, which is capable of in-furnace desulfurization, characterized by: The rotary kiln incinerator comprises the rotary kiln incinerator and the following steps. S1. When the rotary kiln incineration system is working, the desulfurizing agent injection pipe (12) injects raw lime or limestone as a desulfurizing agent above the flame injection port (110) to perform desulfurization, and the desulfurizing agent is contacted and fully mixed with the outer axial flow air injected by the first flow air channel (111) or the inner spiral flow air injected by the second flow air channel (113), so that the desulfurizing agent and the flue gas are fully and uniformly contacted. S2. The temperature of the rotary kiln and the residence time of the solid waste are controlled, and the desulfurization product is discharged from the discharge port together with the slag or from the flue gas outlet together with the flue gas.

5. The in-situ desulfurizable rotary kiln incinerator of claim 4, wherein: The maximum particle size of the raw lime or limestone desulfurizing agent is not more than 65 μm, the average particle size is 30-50 μm, and the content of CaO or CaCO 3 in the desulfurizing agent is greater than 90%. When the rotary kiln incineration system is working, the molar ratio of calcium to sulfur in the cylinder is 2-3, the temperature in the rotary kiln is 800-1000℃, and the residence time of the solid waste in the rotary kiln is 30-60 minutes.

6. The in-situ desulfurizable rotary kiln incinerator of claim 5, wherein: The excess air coefficient in the rotary kiln is 1.2-2.

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