Sludge incineration flue gas denitration device and method

Abstract

The application discloses a sludge incineration flue gas denitration device, which comprises a flue gas heat exchanger, a cold side flue gas inlet, a cold side flue gas outlet, a hot side flue gas inlet and a hot side flue gas outlet, the cold side flue gas inlet is connected with a flue for flue gas to be denitrated, and the hot side flue gas outlet is connected with a flue for discharging flue gas; two flues, the inlets of which are connected with the cold side outlet of the flue gas heat exchanger, a flue valve is arranged on the first flue, and a flue fan, a burner, a flue venturi, a first temperature detector and a urea lance are sequentially arranged on the second flue; a mixed flue, the inlet of which is connected with the outlets of the two flues, and a flue mixer, a second temperature detector and an SCR reactor are sequentially arranged on the mixed flue, and the outlet of the mixed flue is connected with the hot side flue gas inlet. The application further discloses a sludge incineration flue gas denitration method. The application does not need to arrange a urea pyrolysis tower, saves the land occupation area, realizes high-temperature pyrolysis of urea by heating part of flue gas, improves the heat utilization rate and saves fuel.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and more specifically, to a sludge incineration flue gas denitrification device and method. Background Technology

[0002] Sludge produces NO during incineration x Gaseous pollutants such as sludge require flue gas denitrification and purification. Selective non-catalytic reduction (SNCR) is commonly used for denitrification of flue gas from sludge incineration. However, due to significant differences in sludge composition across different regions and increasingly stringent environmental standards, selective catalytic reduction (SCR), which offers higher denitrification efficiency and more stable performance, is often required.

[0003] SCR denitrification units are usually located at the end of flue gas treatment. Because the flue gas temperature is low, urea cannot be pyrolyzed to generate NH3 required for denitrification. A separate urea pyrolysis furnace is required. After the urea is decomposed in the pyrolysis furnace, NH3 is generated and then mixed with the incineration flue gas, which then undergoes a catalytic reduction reaction.

[0004] Currently, the SCR devices on the market have the following main shortcomings in the application of sludge incineration:

[0005] (1) Conventional SCR requires a urea pyrolysis tower, which has a high investment cost;

[0006] (2) The urea pyrolysis tower and its supporting equipment result in a complex process and require a large amount of space for layout;

[0007] (3) Urea pyrolysis requires a large amount of fuel, resulting in high operating costs. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a sludge incineration flue gas denitrification device and method.

[0009] This invention provides a sludge incineration flue gas denitrification device and method, the device comprising:

[0010] A flue gas heat exchanger is provided with a cold-side flue gas inlet, a cold-side flue gas outlet, a hot-side flue gas inlet, and a hot-side flue gas outlet. The cold-side flue gas inlet is connected to the flue gas duct to be denitrified, and the hot-side flue gas outlet is connected to the flue gas discharge duct.

[0011] The two flues are connected to the cold side flue gas outlet at their inlets. The first flue is equipped with a flue valve, and the second flue is equipped with a flue fan, a burner, a flue venturi, a first temperature gauge, and a urea spray gun connected in sequence.

[0012] A mixing flue, the inlet of which is connected to the outlet of the two flues, is provided with a flue mixer, a second temperature sensor and an SCR reactor connected in sequence on the mixing flue, and the outlet of the mixing flue is connected to the hot-side flue gas inlet.

[0013] As a further improvement of the present invention, the operating frequency of the flue fan is adjustable, the opening degree of the flue valve is adjustable, and the operating frequency of the flue fan and the opening degree of the flue valve are interlocked with the signal of the first temperature detection meter.

[0014] The heat load of the burner is adjustable, and the heat load of the burner is interlocked with the signal of the second temperature detection gauge.

[0015] As a further improvement of the present invention, the flue gas exhaust duct is equipped with an NH3 concentration detector and an NO detector connected in sequence. x Concentration meter and exhaust fan;

[0016] The operating frequency of the flue fan, the opening degree of the flue valve, and the heat load signal of the burner are compared with the NH3 concentration meter and the NO concentration meter. x The concentration detection meter signal is interlocked, and it has a catalyst regeneration function.

[0017] As a further improvement of the present invention, the urea spray gun adopts a dual-fluid atomizing spray gun. The urea spray gun is provided with a first interface and a second interface, which are respectively connected to a compressed air pipeline and a urea solution pipeline. A metering pump and a flow meter are connected in sequence on the urea solution pipeline.

[0018] The operating frequency of the metering pump is adjustable, and the operating frequency of the metering pump is related to the NO. x The concentration detection meter signal is interlocked.

[0019] As a further improvement of the present invention, the SCR reactor is provided with at least two layers of catalyst, one of which serves as a backup catalyst layer, and each catalyst layer is equipped with a differential pressure gauge.

[0020] The present invention also provides a method for denitrification of flue gas from sludge incineration, the method comprising:

[0021] The flue gas to be denitrified after sludge incineration enters the flue gas heat exchanger through the cold side flue gas inlet for heat exchange and temperature increase. The flue gas after heat exchange is discharged through the cold side flue gas outlet. The discharged flue gas is divided into two parts: one part flows through the flue valve, and the other part flows through the flue fan to enter the burner for heating.

[0022] The heated flue gas forms a flue gas flow through the flue venturi, and mixes with the flue gas flow through the urea atomized liquid sprayed by the urea spray gun, and heats up to the point where the urea undergoes a pyrolysis reaction. The urea pyrolysis produces flue gas containing ammonia. At the same time, the first temperature of the flue gas flow is detected in real time by the first temperature detection gauge, and the operating frequency of the flue fan and the opening of the flue valve are adjusted according to the first temperature to ensure that the adjusted first temperature meets the first preset condition.

[0023] The flue gas containing ammonia is mixed with the flue gas flowing out of the flue valve and enters the flue mixer and SCR reactor. The ammonia in the flue gas undergoes a catalytic reduction reaction in the SCR reactor to complete the flue gas denitrification and purification. At the same time, the second temperature of the flue gas entering the SCR reactor is detected in real time by a second temperature detector, and the heat load of the burner is adjusted according to the second temperature so that the adjusted second temperature meets the second preset condition.

[0024] The denitrified flue gas enters the flue gas heat exchanger through the hot-side flue gas inlet and is discharged through the hot-side flue gas outlet.

[0025] As a further improvement of the present invention, the first preset condition includes: the first temperature is greater than or equal to the urea pyrolysis temperature and less than or equal to the urea oxidation temperature; adjusting the operating frequency of the flue fan and the opening degree of the flue valve according to the first temperature to ensure that the adjusted first temperature meets the first preset condition, including:

[0026] When the first temperature is greater than the urea oxidation temperature, the operating frequency of the flue fan is increased and the opening of the flue valve is decreased.

[0027] When the first temperature is lower than the urea pyrolysis temperature, the operating frequency of the flue fan is reduced and the opening of the flue valve is increased.

[0028] As a further improvement of the present invention, the second preset condition includes: the second temperature is greater than or equal to the lower limit of the catalytic reduction reaction and less than or equal to the upper limit of the catalytic reduction reaction temperature; adjusting the heat load of the burner according to the second temperature so that the adjusted second temperature meets the second preset condition, including:

[0029] When the second temperature is greater than the upper temperature limit of the catalytic reduction reaction, the heat load of the burner is reduced.

[0030] When the second temperature is lower than the lower limit of the catalytic reduction reaction temperature, the heat load of the burner is increased.

[0031] As a further improvement of the present invention, the method further includes, in real time, detecting the flow rate of the urea solution entering the urea spray gun using a flow meter, and using NO... xThe concentration detection instrument monitors the NO concentration in the flue gas after denitrification and purification in real time. x Concentration, and based on the detected NO x Concentration adjustment of the operating frequency of the flow meter and metering pump includes:

[0032] When NO is detected x When the concentration is greater than a preset threshold, the operating frequency of the metering pump is increased;

[0033] When NO is detected x When the concentration is less than a preset threshold, the operating frequency of the metering pump is reduced.

[0034] As a further improvement of the present invention, the method further includes: real-time detection of the NH3 concentration in the denitrification purified flue gas using an NH3 concentration detector, so as to determine the concentration based on the detected NH3 concentration and the NO concentration. x The concentration for catalyst regeneration in the SCR reactor includes:

[0035] When the NH3 concentration and the NO x When the concentration is simultaneously greater than the preset threshold, the flue valve is closed, and the operating frequency of the flue fan and the heat load of the burner are increased so that the first temperature and the second temperature are simultaneously greater than the catalyst regeneration temperature, and the catalyst regeneration process is carried out.

[0036] The beneficial effects of this invention are as follows:

[0037] The unit eliminates the need for a separate urea pyrolysis tower, and the flue gas flow is arranged in a "U" shape, reducing the equipment footprint and lowering operating costs and investment. By installing a flue gas heat exchanger, the high-temperature purified flue gas discharged from the SCR reactor exchanges heat with the low-temperature flue gas to be denitrated, recovering the waste heat of the high-temperature flue gas and cooling it to a certain temperature, while simultaneously heating the flue gas to be denitrated, thereby reducing the heat load on the burner and saving energy. By installing a flue fan and burner, a portion of the flue gas discharged from the cold side of the flue gas heat exchanger is heated and heated to the urea pyrolysis temperature, and then exchanged heat with the urea. The heated flue gas is then mixed with the remaining low-temperature flue gas to be denitrated before entering the SCR reactor, maximizing the utilization of thermal energy, saving fuel required for urea pyrolysis, and reducing operating costs. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a sludge incineration flue gas denitrification device according to an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the flue gas denitrification process of a sludge incineration flue gas denitrification device according to an embodiment of the present invention.

[0041] In the picture,

[0042] 1. Flue gas heat exchanger; 2. Flue gas fan; 3. Burner; 4. Flue gas venturi; 5. First temperature gauge; 6. Metering pump; 7. Flow meter; 8. Urea spray gun; 9. Flue gas valve; 10. Flue gas mixer; 11. Second temperature gauge; 12. SCR reactor; 13. Differential pressure gauge; 14. Catalyst; 15. NH3 concentration gauge; 16. NO x Concentration meter; 17. Exhaust fan. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0045] Furthermore, the terminology used in the description of this invention is for illustrative purposes only and is not intended to limit the scope of the invention. The terms "comprising" and / or "including" are used to specify the presence of said elements, steps, operations, and / or components, but do not exclude the presence or addition of one or more other elements, steps, operations, and / or components. The terms "first," "second," etc., may be used to describe various elements, do not represent an order, and do not limit these elements. Moreover, in the description of this invention, unless otherwise stated, "a plurality of" means two or more. These terms are used only to distinguish one element from another. These and / or other aspects become apparent in conjunction with the following drawings, and those skilled in the art will more readily understand the description of the embodiments of the invention. The drawings are used for illustrative purposes only to depict the embodiments of the invention. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods shown in the invention can be employed without departing from the principles of the invention.

[0046] like Figure 1 As shown in the embodiment of the present invention, a sludge incineration flue gas denitrification device includes:

[0047] Flue gas heat exchanger 1 is provided with a cold side flue gas inlet, a cold side flue gas outlet, a hot side flue gas inlet and a hot side flue gas outlet. The cold side flue gas inlet is connected to the flue gas duct to be denitrified, and the hot side flue gas outlet is connected to the flue gas discharge duct.

[0048] The two flues are connected at their inlets to the cold side flue gas outlet of the flue gas heat exchanger 1. The first flue is equipped with a flue valve 9, and the second flue is equipped with a flue fan 2, a burner 3, a flue venturi 4, a first temperature measuring gauge 5, and a urea spray gun 8 connected in sequence.

[0049] A mixing flue, the inlet of which is connected to the outlet of the two flues, is provided with a flue mixer 10, a second temperature sensor 11 and an SCR reactor 12 connected in sequence on the mixing flue, and the outlet of the mixing flue is connected to the hot-side flue gas inlet.

[0050] In this application, the flue gas to be denitrified enters through the cold-side flue gas inlet of the flue gas heat exchanger 1, and after heat exchange in the flue gas heat exchanger 1, it is discharged through the cold-side flue gas outlet. The discharged flue gas is divided into two paths. Part of the flue gas enters the flue valve 9 through the first flue, and part of the flue gas enters the flue fan 2 through the second flue. By adjusting the fan frequency, the flue gas is blown into the burner 3. In the burner 3, the flue gas is heated by burning natural gas, thus saving the fuel required for urea pyrolysis. The heated flue gas forms a rotating upward flue gas flow under the action of the flue venturi 4. Furthermore, through the flue venturi 4, the flue gas flow and the urea atomized liquid sprayed from the urea spray gun 8 achieve better contact, prolonging their residence time in the second flue. The first temperature gauge 5 monitors the flue gas temperature in real time to ensure that the flue gas temperature meets the temperature conditions for urea pyrolysis and the temperature conditions for urea non-oxidation. After monitoring, the urea atomized liquid sprayed from the urea spray gun 8 exchanges heat with the flue gas to raise its temperature until the urea undergoes a pyrolysis reaction to produce flue gas containing ammonia. The high-temperature flue gas containing ammonia and the low-temperature flue gas to be denitrated flowing through the first flue enter the mixing flue together. A flue gas mixer 10 is installed before the inlet of the SCR reactor 12 to fully mix the flue gas entering the mixing flue, ensuring that the flue gas temperature entering the SCR reactor 12 is uniform and stable. The second temperature gauge 11 is installed between the flue gas mixer 10 and the SCR reactor 12 for real-time monitoring of the flue gas temperature to ensure that the temperature of the mixed flue gas meets the temperature conditions for the catalytic reduction reaction. The hot-side flue gas inlet is connected to the outlet of the SCR reactor 12, and the flue gas undergoes heat exchange treatment in the flue gas heat exchanger 1. The high-temperature purified flue gas discharged from the SCR reactor 12 enters the flue gas heat exchanger 1 through the hot-side flue gas inlet. The high-temperature purified flue gas is used to heat the flue gas to be denitrified, realizing the recovery and utilization of the waste heat of the high-temperature purified flue gas. At the same time, it reduces the heat load of the burner 3 and avoids the waste of heat energy of the burner 3 caused by excessively high flue gas temperature.

[0051] Existing sludge incineration flue gas denitrification units require a separate urea pyrolysis tower. The design and manufacture of urea pyrolysis towers are complex, requiring consideration of urea's pyrolysis conditions and physical properties, thus necessitating specialized design and manufacturing technologies, increasing equipment manufacturing costs. Furthermore, urea pyrolysis towers consume significant amounts of energy and fuel during operation, increasing operating costs, and their large footprint increases space requirements. In addition, maintenance and repair of urea pyrolysis towers also incur costs. The device described in this application does not require a separate urea pyrolysis tower. The device is arranged in a "U" shape along the flue gas flow direction. Specifically, the flue gas to be denitrated passes through the flue gas heat exchanger 1 from bottom to top, splitting into two paths. One path passes through the flue valve 9, while the other path passes through the flue fan 2, the burner 3, the flue venturi 4, and the first temperature gauge 5 before reaching the highest point of the device. The two paths are then mixed and passed from top to bottom through the flue mixer 10, the second temperature gauge 11, the SCR reactor 12, and the flue gas heat exchanger 1. The device is simple to operate, improves energy efficiency, eliminates the need for a urea pyrolysis tower, reduces the equipment footprint, and saves on construction investment.

[0052] The device described in this application uses a flue gas heat exchanger 1 to exchange heat with the low-temperature flue gas to be denitrated by the high-temperature purified flue gas discharged from the SCR reactor 12. This recovers the waste heat of the high-temperature flue gas and cools it down to a certain temperature (e.g., 110°C), while simultaneously heating the flue gas to be denitrated. This reduces the heat load on the burner 3 and saves energy. Furthermore, by using a flue fan 2 and a burner 3, a portion of the flue gas to be denitrated discharged from the cold side outlet of the flue gas heat exchanger 1 is heated to the urea pyrolysis temperature. After heating, the flue gas mixes with the remaining flue gas to be denitrated and enters the SCR reactor 12 together, maximizing the utilization of thermal energy, reducing fuel consumption, and lowering operating costs.

[0053] In one embodiment, the operating frequency of the flue fan 2 is adjustable, the opening degree of the flue valve 9 is adjustable, and the operating frequency of the flue fan 2 and the opening degree of the flue valve 9 are interlocked with the signal of the first temperature detection meter 5; the heat load of the burner 3 is adjustable, and the heat load of the burner 3 is interlocked with the signal of the second temperature detection meter 11.

[0054] This application includes a first temperature sensor 5, whose signal is interlocked with the signals of the flue fan 2 and the flue valve 9. Based on the temperature data (i.e., the first temperature) fed back by the first temperature sensor 5, the operating frequency of the flue fan 2 and the opening of the flue valve 9 are adjusted to achieve optimal flue gas volume matching between the two flue gas outlets on the cold side of the flue gas heat exchanger 1. The temperature detected by the first temperature sensor 5 needs to be maintained within a certain range (e.g., between 400℃ and 600℃). Within this temperature range, the urea sprayed by the urea spray gun 8 can undergo a pyrolysis reaction, while oxidation of the urea can be avoided. If the temperature data detected by the first temperature sensor 5 exceeds the maximum value (i.e., the urea oxidation temperature) or falls below the minimum value (i.e., the urea pyrolysis temperature) within this range, the operating frequency of the flue fan 2 and the opening of the flue valve 9 need to be adjusted simultaneously so that the temperature data detected again after adjustment falls within the temperature range. When the temperature data detected by the first temperature sensor 5 is greater than the urea oxidation temperature, the operating frequency of the flue fan is increased and the opening of the flue valve is decreased; when the temperature data detected by the first temperature sensor 5 is less than the urea pyrolysis temperature, the operating frequency of the flue fan is decreased and the opening of the flue valve is increased.

[0055] For example, the initial operating frequency of the flue fan 2 is set to 40Hz, and the initial opening of the flue valve 9 is set to 50%. The flue gas temperature is monitored in real time by the first temperature sensor 5 and maintained between 400℃ and 600℃. When the detected temperature exceeds 600℃, the operating frequency of the flue fan is increased, while the opening of the flue valve is decreased to supplement the amount of flue gas entering the burner 3. By adjusting the operating frequency of the flue fan 2 and the opening of the flue valve 9, the optimal flue gas volume matching is achieved at the cold-side flue gas outlet of the flue gas heat exchanger 1. The above adjustment can be manual or automatic.

[0056] This application also includes a second temperature sensor 11, whose signal is interlocked with that of the burner 3. The heat load of the burner 3 is adjusted based on the temperature data (i.e., the second temperature) fed back by the second temperature sensor 11, ensuring that the burner can obtain heat to heat the flue gas under optimal conditions. The temperature detected by the second temperature sensor 11 needs to be maintained within a certain range (e.g., between 230°C and 260°C). This temperature range ensures the activity of the catalyst inside the SCR reactor 12, guaranteeing the proper functioning of NH3 and NO. xWhile the oxidation-reduction reaction occurs, excessively high flue gas temperatures are avoided, preventing heat energy waste in burner 3. If the temperature data detected by the second temperature sensor 11 exceeds the maximum value within the range (i.e., the upper temperature limit of the catalytic reduction reaction) or falls below the minimum value within the range (i.e., the lower temperature limit of the catalytic reduction reaction), the heat load of burner 3 needs to be adjusted so that the temperature data detected again after adjustment falls within the range. When the temperature data detected by the second temperature sensor 11 exceeds the upper temperature limit of the catalytic reduction reaction, the heat load of burner 3 is reduced; when the temperature data detected by the second temperature sensor 11 is below the lower temperature limit of the catalytic reduction reaction, the heat load of burner 3 is increased.

[0057] For example, when the detected temperature is higher than 260℃, the heat load of burner 3 is reduced; when the detected temperature is lower than 230℃, the heat load of burner 3 is increased. Furthermore, the operating frequency of the flue fan 2 can be adjusted to assist burner 3 in regulating the flue gas temperature, so that the flue gas temperature is stabilized between 230℃ and 260℃.

[0058] In one embodiment, an NH3 concentration meter 15 and an NO meter 15 are sequentially connected to the flue gas exhaust duct. x The concentration detection table 16 and the induced draft fan 17; the operating frequency of the flue fan 2, the opening degree of the flue valve 9, and the heat load signal of the burner 3 are compared with the NH3 concentration detection table 15 and the NO concentration detection table 17. x The concentration detection gauge 16 signal is interlocked, and it has the function of catalyst 14 regeneration.

[0059] Flue gas containing ammonia reacts with NO inside the SCR reactor 12 using catalyst 14 as a medium. x A redox reaction occurs, completing the denitrification and purification of the flue gas. The target NO emission level for the purified flue gas is then set. x Concentration and NH3 concentration, and measured through NH3 concentration detection table 15 and NO x Table 16 shows the real-time detection of NH3 and NO in flue gas. x Concentration levels, ensuring that the emitted flue gas contains NH3 and NO. x The concentration meets the standard, and the qualified flue gas is discharged through the induced draft fan 17.

[0060] In addition, to maintain the reactivity of the catalyst 14 in the SCR reactor 12, the operating frequency of the flue fan 2, the opening degree of the flue valve 9, and the heat load signal of the burner 3 are monitored in conjunction with the NH3 concentration meter and the NO concentration meter. x The concentration meter signal is interlocked, allowing real-time monitoring of the NH3 concentration in the denitrification purified flue gas. The detected NH3 concentration can be used to determine the relative concentrations of NO and other gases. xThe concentration of NH3 and NO is used to regenerate the catalyst in SCR reactor 12. x When the concentrations of NH3 and NO are simultaneously greater than the preset threshold, it indicates that the activity of catalyst 14 has decreased and regeneration is required. At this time, the flue valve 9 is closed, and the operating frequency of the flue fan 2 and the heat load of the burner 3 are increased so that the first temperature detected by the first temperature sensor 5 and the second temperature detected by the second temperature sensor 11 are simultaneously greater than the regeneration temperature of catalyst 14, thus initiating the catalyst regeneration process. This process continues for a period of time until the concentrations of NH3 and NO are both greater than the preset threshold. x Once the concentration detection data decreases simultaneously, the catalyst regeneration process is complete.

[0061] For example, during the online regeneration of catalyst 14, flue valve 9 is completely closed, while the operating frequency of flue fan 2 is increased, and the natural gas supply to burner 3 is continuously increased, increasing the heat load until the temperature detected by the first temperature sensor 5 reaches approximately 350°C, at which point the regeneration condition is met. This condition is maintained for approximately 2 hours, and the NH3 concentration sensor 15 and NO concentration are continuously monitored. x The concentration changes detected by the concentration detection table 16 are monitored. Once both data return to normal, the regeneration of catalyst 14 is stopped. Each catalytic regeneration session should not exceed 6 hours. If catalyst 14 still cannot regain its reactivity after regeneration, it is considered aged and needs to be replaced.

[0062] By regenerating the catalyst 14 online, the activity of the catalyst 14 is restored, the service life of the catalyst 14 is extended, and the frequent replacement of the catalyst 14 is avoided, thus saving the consumption of raw materials and energy and reducing production costs.

[0063] In one embodiment, the urea spray gun 8 is a dual-fluid atomizing spray gun. The urea spray gun 8 has a first interface and a second interface, respectively connected to a compressed air pipeline and a urea solution pipeline. A metering pump 6 and a flow meter 7 are connected in sequence on the urea solution pipeline. The metering pump 6 is a variable frequency pump, and its operating frequency is adjustable. The operating frequency of the metering pump 6 is related to the NO... x Concentration detection table 16 signal interlock.

[0064] The urea spray gun 8 described in this application employs a dual-fluid atomizing spray gun, enabling the compressed air and urea solution to form a uniform atomized liquid that is discharged from the nozzle of the spray gun. The atomized urea liquid mixes with the NO in the flue gas flowing out of the flue venturi 4. xA chemical reaction occurs, and through efficient atomization and mixing, urea can more fully contact nitrogen oxides, improving the efficiency of the catalytic reduction reaction. The urea spray gun 8 can achieve precise control of the urea injection dosage, and the resulting urea spray cross-sectional shape is similar to the cross-sectional shape of the second flue, with the lower edge of the spray shape higher than the height of the flue venturi 4. The heated flue gas and spray spiral upward in the flue venturi 4, prolonging the residence time of the flue gas in the flue, which is conducive to better mixing of high-temperature flue gas and urea spray, and improving the contact effect of the flue gas.

[0065] The flow meter 7 detects the flow rate of the urea solution entering the urea spray gun in real time, and the metering pump 6 adjusts the flow rate of the urea solution. This application also includes a feature that interlocks the operating frequency of the metering pump 6 with the signal from the NOx concentration detection meter 16. When NO... x NO detected in Table 16 x When the concentration exceeds the target emission concentration (i.e., the preset threshold), the operating frequency of the metering pump 6 is increased to replenish the urea solution. When NO is detected... x If the concentration is below the preset threshold, reduce the operating frequency of metering pump 6.

[0066] The interlocking control process described in this application is executed automatically according to the electronic control program. Under special circumstances, it can also be manually adjusted by the operator, and then switched to automatic control after the situation is restored.

[0067] In one embodiment, the SCR reactor 12 is provided with at least two layers of catalyst 14, one of which serves as a spare layer of catalyst 14, and each layer of catalyst 14 is provided with a differential pressure gauge 13.

[0068] Catalyst 14 in this application is a denitrification catalyst with medium- and low-temperature reaction activity. Catalyst 14 can ensure that NH3 and NO in the flue gas react within a certain temperature range (230℃~260℃). x It has redox reactivity and can increase the redox reaction activity of NH3 and NO. x The denitrification reaction efficiency is improved. The catalyst 14 has at least two layers: one for catalytic reduction and one as a backup. Even if one layer of catalyst 14 completely loses its activity, the backup catalyst 14 can still function. It is understood that the catalyst 14 can also have three, four, or other layers, and can be adaptively adjusted according to usage requirements. This application does not impose a specific limitation on the number of layers of catalyst 14. A differential pressure gauge 13 is used to monitor the differential pressure of the catalyst 14 in real time. When the data detected by the differential pressure gauge 13 is high, it indicates that the pores of the corresponding catalyst 14 are blocked. At this time, a cleaning operation needs to be initiated to resolve the pore blockage problem of the corresponding layer of catalyst 14.

[0069] This invention also provides a method for denitrification of flue gas from sludge incineration, the method comprising:

[0070] The flue gas to be denitrified after sludge incineration enters the flue gas heat exchanger 1 through the cold side flue gas inlet for heat exchange and temperature increase. The flue gas after heat exchange is discharged through the cold side flue gas outlet. The discharged flue gas is divided into two parts: one part flows through the flue valve 9, and the other part flows through the flue fan 2 and enters the burner 3 for heating.

[0071] The heated flue gas forms a flue gas flow through the flue venturi 4, and mixes and exchanges heat with the flue gas flow through the urea atomized liquid sprayed by the urea spray gun 8, and the temperature rises to the point where the urea undergoes a pyrolysis reaction. The urea pyrolysis produces flue gas containing ammonia. At the same time, the first temperature of the flue gas flow is detected in real time by the first temperature detection gauge 5, and the operating frequency of the flue fan 3 and the opening of the flue valve 9 are adjusted according to the first temperature so that the adjusted first temperature meets the first preset condition.

[0072] The flue gas containing ammonia is mixed with the flue gas flowing out of the flue valve 9 and enters the flue mixer 10 and the SCR reactor 12. The ammonia in the flue gas undergoes a catalytic reduction reaction in the SCR reactor 12 to complete the flue gas denitrification and purification. At the same time, the second temperature of the flue gas entering the SCR reactor 12 is detected in real time by the second temperature detection gauge 11, and the heat load of the burner 3 is adjusted according to the second temperature so that the adjusted second temperature meets the second preset condition.

[0073] The denitrified flue gas enters the flue gas heat exchanger 1 through the hot-side flue gas inlet and is discharged through the hot-side flue gas outlet.

[0074] In one embodiment, the first preset condition includes: the first temperature is greater than or equal to the urea pyrolysis temperature and less than or equal to the urea oxidation temperature; adjusting the operating frequency of the flue fan 2 and the opening degree of the flue valve 9 according to the first temperature to ensure that the adjusted first temperature meets the first preset condition, including:

[0075] When the first temperature is greater than the urea oxidation temperature, the operating frequency of the flue fan 2 is increased and the opening of the flue valve 9 is decreased.

[0076] When the first temperature is lower than the urea pyrolysis temperature, the operating frequency of the flue fan 2 is reduced and the opening of the flue valve 9 is increased.

[0077] In one embodiment, the second preset condition includes: the second temperature is greater than or equal to the lower limit of the catalytic reduction reaction and less than or equal to the upper limit of the catalytic reduction reaction; adjusting the heat load of the burner 3 according to the second temperature so that the adjusted second temperature meets the second preset condition, including:

[0078] When the second temperature is greater than the upper temperature limit of the catalytic reduction reaction, the heat load of the burner 3 is reduced.

[0079] When the second temperature is lower than the lower limit of the catalytic reduction reaction temperature, the heat load of the burner 3 is increased.

[0080] In one embodiment, the method further includes detecting the flow rate of the urea solution entering the urea spray gun 8 in real time using a flow meter 7, and using NO... x Table 16 shows the real-time monitoring of NO concentration in the flue gas after denitrification and purification. x Concentration, and based on the detected NO x The concentration adjustment of the operating frequency of the flow meter 7 and the metering pump 6 includes:

[0081] When the detected NOx concentration is greater than a preset threshold, the operating frequency of the metering pump 6 is increased.

[0082] When the detected NOx concentration is less than a preset threshold, the operating frequency of the metering pump 6 is reduced.

[0083] In one embodiment, the method further includes: real-time detection of the NH3 concentration in the denitrification purified flue gas using an NH3 concentration detection table 15, so as to determine the concentration based on the detected NH3 concentration and the NO concentration. x The concentration is used to regenerate the catalyst 14 in the SCR reactor 12, including:

[0084] When the NH3 concentration and the NO x When the concentration is simultaneously greater than the preset threshold, the flue valve 9 is closed, and the operating frequency of the flue fan 2 and the heat load of the burner 3 are increased so that the first temperature and the second temperature are simultaneously greater than the regeneration temperature of the catalyst 14, and the catalyst 14 regeneration process is carried out.

[0085] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0086] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0087] Those skilled in the art will understand that although the invention has been described with reference to exemplary embodiments, various changes may be made and its elements may be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of the invention without departing from the essential scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed, but rather the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A sludge incineration flue gas denitrification device, characterized in that, The device includes: A flue gas heat exchanger is provided with a cold-side flue gas inlet, a cold-side flue gas outlet, a hot-side flue gas inlet, and a hot-side flue gas outlet. The cold-side flue gas inlet is connected to the flue gas duct to be denitrified, and the hot-side flue gas outlet is connected to the flue gas discharge duct. The two flues are connected to the cold side flue gas outlet at their inlets. The first flue is equipped with a flue valve, and the second flue is equipped with a flue fan, a burner, a flue venturi, a first temperature gauge, and a urea spray gun connected in sequence. A mixing flue, the inlet of which is connected to the outlet of the two flues, is provided with a flue mixer, a second temperature sensor and an SCR reactor connected in sequence on the mixing flue, and the outlet of the mixing flue is connected to the hot-side flue gas inlet; The operating frequency of the flue fan is adjustable, the opening degree of the flue valve is adjustable, and the operating frequency of the flue fan and the opening degree of the flue valve are interlocked with the signal of the first temperature detection meter; the heat load of the burner is adjustable, and the heat load of the burner is interlocked with the signal of the second temperature detection meter.

2. The apparatus according to claim 1, characterized in that, The flue gas exhaust duct is equipped with an NH3 concentration detector and an NO concentration detector connected in sequence. x Concentration meter and exhaust fan; The operating frequency of the flue fan, the opening degree of the flue valve, and the heat load signal of the burner are compared with the NH3 concentration meter and the NO concentration meter. x The concentration detection meter signal is interlocked, and it has a catalyst regeneration function.

3. The apparatus according to claim 2, characterized in that, The urea spray gun is a dual-fluid atomizing spray gun. The urea spray gun is provided with a first interface and a second interface, which are respectively connected to a compressed air pipeline and a urea solution pipeline. A metering pump and a flow meter are connected in sequence on the urea solution pipeline. The operating frequency of the metering pump is adjustable, and the operating frequency of the metering pump is related to the NO. x The concentration detection meter signal is interlocked.

4. The apparatus according to claim 1, characterized in that, The SCR reactor is equipped with at least two layers of catalyst, one of which serves as a backup catalyst layer, and each catalyst layer is equipped with a differential pressure gauge.

5. A flue gas denitrification method for a sludge incineration flue gas denitrification device as described in any one of claims 1-4, characterized in that, The method includes: The flue gas to be denitrified after sludge incineration enters the flue gas heat exchanger through the cold side flue gas inlet for heat exchange and temperature increase. The flue gas after heat exchange is discharged through the cold side flue gas outlet. The discharged flue gas is divided into two parts: one part flows through the flue valve, and the other part flows through the flue fan to enter the burner for heating. The heated flue gas forms a flue gas flow through the flue venturi, and mixes with the flue gas flow through the urea atomized liquid sprayed by the urea spray gun, and heats up to the point where the urea undergoes a pyrolysis reaction. The urea pyrolysis produces flue gas containing ammonia. At the same time, the first temperature of the flue gas flow is detected in real time by the first temperature detection gauge, and the operating frequency of the flue fan and the opening of the flue valve are adjusted according to the first temperature to ensure that the adjusted first temperature meets the first preset condition. The flue gas containing ammonia is mixed with the flue gas flowing out of the flue valve and enters the flue mixer and SCR reactor. The ammonia in the flue gas undergoes a catalytic reduction reaction in the SCR reactor to complete the flue gas denitrification and purification. At the same time, the second temperature of the flue gas entering the SCR reactor is detected in real time by a second temperature detector, and the heat load of the burner is adjusted according to the second temperature so that the adjusted second temperature meets the second preset condition. The denitrified flue gas enters the flue gas heat exchanger through the hot-side flue gas inlet and is discharged through the hot-side flue gas outlet.

6. The method according to claim 5, characterized in that, The first preset condition includes: the first temperature is greater than or equal to the urea pyrolysis temperature and less than or equal to the urea oxidation temperature; adjusting the operating frequency of the flue fan and the opening of the flue valve according to the first temperature to ensure that the adjusted first temperature meets the first preset condition, including: When the first temperature is greater than the urea oxidation temperature, the operating frequency of the flue fan is increased and the opening of the flue valve is decreased. When the first temperature is lower than the urea pyrolysis temperature, the operating frequency of the flue fan is reduced and the opening of the flue valve is increased.

7. The method according to claim 5, characterized in that, The second preset condition includes: the second temperature is greater than or equal to the lower limit of the catalytic reduction reaction temperature and less than or equal to the upper limit of the catalytic reduction reaction temperature. The heat load of the burner is adjusted according to the second temperature to ensure that the adjusted second temperature meets the second preset condition, including: When the second temperature is greater than the upper temperature limit of the catalytic reduction reaction, the heat load of the burner is reduced. When the second temperature is lower than the lower limit of the catalytic reduction reaction temperature, the heat load of the burner is increased.

8. The method according to claim 5, characterized in that, The method further includes detecting the flow rate of the urea solution entering the urea spray gun in real time using a flow meter, and detecting the flow rate of NO... x The concentration detection instrument monitors the NO concentration in the flue gas after denitrification and purification in real time. x Concentration, and based on the detected NO x Concentration adjustment of the operating frequency of the flow meter and metering pump includes: When NO is detected x When the concentration is greater than a preset threshold, the operating frequency of the metering pump is increased; When NO is detected x When the concentration is less than a preset threshold, the operating frequency of the metering pump is reduced.

9. The method according to claim 8, characterized in that, The method further includes: real-time detection of the NH3 concentration in the denitrification purified flue gas using an NH3 concentration detector, and adjusting the detected NH3 concentration based on the NO concentration. x The concentration for catalyst regeneration in the SCR reactor includes: When the NH3 concentration and the NO x When the concentration is simultaneously greater than the preset threshold, the flue valve is closed, and the operating frequency of the flue fan and the heat load of the burner are increased so that the first temperature and the second temperature are simultaneously greater than the catalyst regeneration temperature, and the catalyst regeneration process is carried out.

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