Process for energy conservation and consumption reduction in cement industry

Abstract

The invention discloses a process for energy conservation and consumption reduction in cement industry, and relates to the technical field of hazardous waste co-processing and flue gas denitration environmental protection, and the process comprises the following steps: step 1, selecting liquid hazardous waste with a heat value within a certain range, and fully atomizing the liquid hazardous waste through compressed air and a special spray gun; step 2, at a calorific value liquid hazardous waste adding point in a denitrification furnace system, spraying the atomized liquid hazardous waste into the denitrification furnace at a high speed; 3, according to the temperature working condition and the NOX concentration in the denitrification furnace system, the pulverized coal injection amount of a coal injection point of the denitrification furnace is reduced, and the ammonia water use amount of the SNCR denitrification system is adjusted; 4, monitoring the concentration, temperature and pressure parameters of gas components such as NOX and CO in the flue gas in real time through a plurality of detection points, and remarkably reducing coal consumption by replacing pulverized coal with liquid dangerous waste heat values; reducing gases such as CO and H2 are supplemented through hazardous waste combustion, so that the self-denitration effect of the denitrification furnace is enhanced, and the consumption of ammonia water is reduced.

Description

Technical Field

[0001] This invention relates to the field of hazardous waste co-processing and flue gas denitrification environmental protection technology, specifically to a process for energy saving and consumption reduction in the cement industry. Background Technology

[0002] In the clinker production process of the cement industry, the high-temperature calcination (1350℃~1700℃) in the rotary kiln and the pre-decomposition of raw materials in the decomposition furnace (800℃~980℃) generate a large amount of thermal and fuel-type NO. X Not only does it harm human health, but it also causes photochemical smog pollution. With increasingly stringent environmental standards, the China Cement Association's group standard, "Ultra-Low Emission Standard for Air Pollutants in the Cement Industry," requires existing cement enterprises to meet NOx emission standards. X Emission concentration ≤100mg / m³ 3 This places higher demands on denitrification technology.

[0003] Currently, mainstream denitrification technologies for cement kilns include self-denitrification in denitrification furnaces, SNCR denitrification systems, and staged combustion. Among these, the denitrification furnace reduces NO₂ produced by the incomplete combustion of pulverized coal using CO. X The SNCR system further reduces the remaining NO by injecting ammonia. X Meanwhile, the co-processing of hazardous waste in cement kilns has become an important method for the harmless treatment of hazardous waste. However, existing technologies for utilizing calorific value liquid hazardous waste are limited to the "disposal" level, failing to fully explore its energy-saving and denitrification potential: the high calorific value of liquid hazardous waste has not been used to replace pulverized coal, resulting in high fuel consumption; the promoting effect of hazardous waste combustion on denitrification reactions has not been developed, leading to persistently high ammonia consumption in SNCR systems; and the dosing location is not well matched with the process, making it impossible to effectively supplement reducing gases to enhance the denitrification effect.

[0004] Therefore, there is an urgent need for a process technology that can deeply integrate the treatment of calorific value liquid hazardous waste with energy-saving denitrification, so as to achieve multiple goals such as high-value utilization of hazardous waste, reduction of coal consumption and improvement of denitrification efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a process for energy saving and consumption reduction in the cement industry, in order to solve the problems of high fuel consumption in existing denitrification furnaces; undeveloped promotion effect of hazardous waste combustion on denitrification reaction; high ammonia water consumption in SNCR system; and insufficient matching between the injection location and process, which makes it impossible to effectively supplement reducing gas to enhance the denitrification effect.

[0006] A process for energy conservation and emission reduction in the cement industry includes the following steps:

[0007] Step 1: Preparation for adding liquid hazardous waste with calorific value: Select liquid hazardous waste with a calorific value in the range of 4500-6000 kcal / kg or 10000-12000 kcal / kg, and fully atomize it using compressed air and a special spray gun;

[0008] Step 2, Selection and Control of Dosing Location: At the dosing point for calorific value liquid hazardous waste within the denitrification furnace system, the atomized liquid hazardous waste is dispensed at a depth of 0.5-1.2m. 3 A flow rate of / h is injected at high speed into the denitrification furnace;

[0009] Step 3: Adjust operating parameters: Based on the temperature and NO conditions within the denitrification furnace system... X To reduce the concentration of pulverized coal and decrease the amount of pulverized coal injected into the denitrification furnace, the temperature of the denitrification furnace system should be kept stable. Simultaneously, based on the NO concentration at the detection points... X Based on the concentration data, adjust the ammonia water dosage of the SNCR denitrification system to ensure that the NO concentration in the flue gas at the chimney outlet is within acceptable limits. X Concentration controlled at 90-100 mg / m³ 3 Within the range;

[0010] Step 4: Effect Monitoring: NO in the flue gas is monitored in real time at detection points set up at the kiln tail flue, the middle of the denitrification furnace, the denitrification furnace outlet, the decomposition furnace outlet, the preheater outlet, and the chimney outlet. X The concentrations of gases such as CO, as well as temperature and pressure parameters, were used to verify the energy-saving denitrification effect.

[0011] Preferably, in step one, the droplet size of the liquid hazardous waste after atomization is controlled at 50-150 μm to ensure complete combustion in the denitrification furnace.

[0012] Preferably, in step two, the point for adding the calorific value liquid hazardous waste is located in the downstream area of ​​the denitrification furnace system, near the coal injection point of the denitrification furnace, and the spraying direction of the spray gun forms an angle of 30°-60° with the flue gas flow direction in the denitrification furnace.

[0013] Preferably, in step three, the reduction in the amount of pulverized coal injected is matched to the calorific value and dosage of the liquid hazardous waste. This is particularly relevant when the calorific value of the liquid hazardous waste is 10000-12000 kcal / kg and the dosage is 0.8-1.2 m³. 3 When the coal powder consumption rate is 6.84-10.68 kg / t·cl., the reduction rate is 6.84-10.68 kg / t·cl.

[0014] Preferably, in step three, the ammonia water dosage of the SNCR denitrification system is adjusted based on online monitoring data at the chimney outlet. When NO X Concentration below 90 mg / m 3 Reduce ammonia usage when it exceeds 100 mg / m³. 3Increasing the amount of ammonia water used can reduce the ammonia water consumption per ton of clinker by 0.11-0.47 kg / t·cl.

[0015] Preferably, in step four, the monitoring frequency of each detection point is not less than once per hour, and the detection data is transmitted to the central control system in real time to guide the adjustment of operating parameters.

[0016] Preferably, this technology is suitable for cement kiln co-processing hazardous waste production lines equipped with denitrification furnaces and SNCR denitrification systems, and can also be applied to power plants, smelters, and other facilities requiring reduced NOx emissions from flue gas. X Industrial kiln systems that emit pollutants.

[0017] The advantages of this invention are as follows: The energy-saving and consumption-reducing process for the cement industry utilizes the calorific value of liquid hazardous waste to replace pulverized coal, significantly reducing coal consumption by 5.28-10.68 kg / t·cl. for actual clinker and 4.53-9.15 kgce / t·cl. for standard coal consumption; the combustion of hazardous waste supplements reducing gases such as CO and H2, enhancing the self-denitrification effect of the denitrification furnace, reducing ammonia water consumption by 0.11-0.47 kg / t·cl. for ammonia water consumption; and transforms calorific value-bearing liquid hazardous waste from "waste" into energy and denitrification auxiliary resources, achieving the dual goals of harmlessness and resource utilization, and maximizing the value of hazardous waste. Attached Figure Description

[0018] Figure 1 This is a process diagram for adding calorific value liquid hazardous waste in this invention.

[0019] The points are as follows: 1. Detection point 1; 2. Coal injection point of denitrification furnace; 3. Slurry and slag addition point; 4. Addition point of calorific value liquid hazardous waste; 5. Detection point 2; 6. Denitrification furnace system; 7. Detection point 3; 8. Tertiary air; 9. Coal injection point of decomposition furnace; 10. Decomposition furnace system; 11. Detection point 4; 12. SNCR denitrification system; 13. Detection point 5; 14. Detection point 6. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] like Figure 1 As shown, a process for energy conservation and consumption reduction in the cement industry includes the following steps:

[0022] Step 1: Preparation for adding liquid hazardous waste with calorific value: Select liquid hazardous waste with a calorific value of 4500-6000 kcal / kg or 10000-12000 kcal / kg, and atomize it into droplets with a particle size of 50-150 μm using compressed air and a special spray gun to ensure complete combustion;

[0023] Step Two: Precise Dosing Control: A dosing point is set up downstream of the pulverized coal injection point within the denitrification furnace system. The spray direction of the nozzle is at a 30°-60° angle to the flue gas flow direction, dispensing the atomized liquid hazardous waste at a distance of 0.5-1.2m. 3 A flow rate of / h is injected at high speed into the denitrification furnace;

[0024] The area through which the flue gas flows is designated as the No. 6 denitrification furnace system. The denitrification mechanism of this system is as follows: pulverized coal is injected from the No. 2 denitrification furnace coal distribution point. A large number of pulverized coal particles undergo incomplete combustion in an oxygen-deficient environment, producing a large amount of CO reducing gas. These reducing gases then react with NO in the flue gas. X An oxidation-reduction reaction occurs, reducing the slurry to non-polluting gases such as N2, thus achieving the purpose of flue gas denitrification in this area. Point 3 in the diagram represents the slurry addition point during normal co-processing. In both the blank test and the industrial test, the slurry at this addition point was in normal operating condition. A high-calorific-value liquid hazardous waste addition point (No. 4 - calorific-value waste liquid addition point) is added at a suitable location within the denitrification furnace pipeline. At this point, the high-calorific-value liquid hazardous waste is fully atomized by compressed air and a special spray gun and then sprayed at high speed into the denitrification furnace. The fully atomized calorific-value hazardous waste droplets undergo incomplete combustion within the denitrification furnace, generating a large amount of heat and reducing gases. To maintain the temperature within the denitrification furnace system at its previous operating conditions, the amount of pulverized coal injected at (No. 2 - denitrification furnace coal distribution point) needs to be reduced, thus reducing the amount of pulverized coal used in the denitrification furnace system and thereby reducing fuel consumption. Although the high calorific value of the waste liquid reduces the amount of pulverized coal used, leading to a decrease in the amount of CO reducing gas generated from pulverized coal in the flue gas, the waste liquid contains a certain amount of water. This water rapidly vaporizes in the high-temperature environment of the denitrification furnace and reacts with the pulverized coal particles: C + H₂O. high temperature The CO + H2 reaction replenishes the CO in the flue gas while simultaneously generating new reducing gas H2. This increases the variety and quantity of reducing gases in the flue gas within the denitrification furnace, thereby enhancing the denitrification effect. This combined effect results in the dual benefits of reducing pulverized coal consumption and promoting flue gas denitrification while conserving ammonia water in the subsequent 12-SNCR denitrification system.

[0025] Step 3: Coordinated Adjustment of Operating Parameters

[0026] Fuel substitution: Based on the calorific value and dosage of the liquid hazardous waste, reduce the amount of pulverized coal used at the pulverized coal injection point of the denitrification furnace to keep the temperature of the denitrification furnace system stable (800℃~980℃);

[0027] Denitrification optimization: Real-time monitoring of NO at detection points XAdjust the ammonia water dosage in the SNCR denitrification system to ensure adequate NO concentration at the chimney outlet. X Concentration controlled at 90-100 mg / m³ 3 ;

[0028] NO in the flue gas of the denitrification furnace after the addition of high-calorific-value liquid hazardous waste X Changes in parameters such as CO concentration can be detected using flue gas detection instruments at points 5 (detection point 2, middle of the denitrification furnace) and 7 (detection point 3, denitrification furnace outlet). After exiting the denitrification furnace system, the flue gas enters the second main reaction unit of the kiln tail preheating and pre-decomposition system—the decomposition furnace system. In the decomposition furnace system, approximately 95% of the CaCO3 in the raw material needs to be decomposed, resulting in about 60% of the fuel (pulverized coal) being consumed. As shown in the diagram, five pulverized coal injection points are set at different locations (point 9, decomposition furnace pulverization point), indicating staged combustion. The oxygen required for combustion is provided by the tertiary air (point 8), thus generating a large amount of NO in the decomposition furnace system (point 10). X NO in flue gas X The concentration can be determined by detection point 4 (decomposition furnace outlet) at serial number 11. The flue gas and entrained raw material powder from the decomposition furnace outlet are divided into two streams and enter the C5A and C5B cyclone separator units respectively. Multiple ammonia water injection points are set at different positions in these two cyclone separator units, which leads to the SNCR denitrification system unit at serial number 12. This SNCR denitrification system, also known as selective non-catalytic reduction technology, mainly uses atomized ammonia water reducing agent to remove the large amount of NO generated in the decomposition furnace. X and the NO remaining after removal by the denitrification furnace X Reduced to non-polluting gases such as N2, ensuring that NO released into the atmosphere is reduced. X The concentration meets environmental emission requirements, as shown in the figure at detection points 13-5 (preheater outlet) and 14-6 (chimney outlet). This is because after denitrification by the SNCR system (number 12), no new NO is generated in the subsequent C4A-C1A and C4B-C1B production processes. X The generation process, therefore, NO at detection points 5 and 6. X The test data are generally quite similar. Six testing points are equipped with online monitoring instruments in accordance with environmental management requirements, allowing for real-time monitoring of flue gas components emitted into the atmosphere around the clock. The SNCR denitrification system (number 12 in the diagram) is the final denitrification stage of the project. The amount of ammonia used as a reducing agent can be adjusted to control the NO content in the flue gas exiting the decomposition furnace. X The reduction control effect ensures that the NO in the flue gas at detection point 6 (chimney outlet) is within the range of serial number 14. X Concentration controlled within the limit (this project requires NO). X Controlled at 90-100 mg / m²3 Within the specified range, that is: the change in the amount of ammonia water used as the reducing agent in the SNCR denitrification system (serial number 12) is actually adjusted in real time by the operators in the central control room based on the fluctuations in the online monitoring data at detection point 6 (chimney outlet) (serial number 14). When the flue gas online monitoring data NO... X Concentration below 90 mg / m 3 When the ammonia usage is reduced, the operator should immediately adjust the ammonia dosage accordingly. When the online flue gas monitoring data shows NO... X Concentration higher than 100 mg / m 3 At this time, the operator will appropriately increase the amount of ammonia water used. Through repeated observation and operation, the online monitoring data NO will be adjusted. X The concentration was consistently and dynamically controlled at 90–100 mg / m³. 3 Within the range.

[0029] Step 4: Full-process effect monitoring: Monitor flue gas temperature, pressure, and NO at least once per hour through monitoring points at the kiln tail flue, the middle of the denitrification furnace, the denitrification furnace outlet, the decomposition furnace outlet, the preheater outlet, and the chimney outlet. X The system monitors CO and O2 concentrations, providing real-time feedback and optimizing operating conditions.

[0030] When the high-temperature flue gas from the cement kiln flows through detection point 1 (kiln tail flue chamber), it enters the first reaction unit of the kiln tail preheating and pre-decomposition system—the denitrification furnace system. At detection point 1, the temperature, pressure parameters, and NO of the flue gas can be detected in real time using flue gas detection instruments. X Concentrations of gaseous components such as CO and O2, with NO... X The concentration can be used as the initial concentration for this study, and the NO concentration in the flue gas at the subsequent 5 detection points can be used as the initial concentration. X The concentration will be related to this initial NO X Concentrations are compared to measure the denitrification effect at various detection points in the denitrification system. Within the denitrification furnace reaction unit, a portion of the raw meal powder introduced into the C4B cyclone separator unit can achieve partial pre-decomposition of the raw meal within the denitrification furnace system.

[0031] Example 1: Experiment on the addition of high-calorific-value liquid hazardous waste

[0032] Hazardous waste preparation: Select liquid hazardous waste with a calorific value of 10,000-12,000 kcal / kg, and atomize it with a special spray gun (nozzle diameter 1.5 mm) and 0.6 MPa compressed air, with the droplet size controlled at 80-120 μm;

[0033] Dosing control: At dosing point 4 of the denitrification furnace system (1.5m downstream of pulverized coal injection point 2 of the denitrification furnace), the dosage is 0.8-1.2m. 3 The spray gun is injected at a flow rate of / h, with an angle of 45° between the spray gun and the direction of flue gas flow.

[0034] Parameter adjustment:

[0035] Coal powder substitution: The amount of coal powder used at point 2 of the denitrification furnace was reduced by 10.68 kg / t·cl. (actual coal consumption), and the temperature of the denitrification furnace was maintained at 850℃-950℃;

[0036] Ammonia water adjustment: Based on the NO at monitoring point 14 (chimney outlet) X Concentration (94.50 mg / m³) 3 The average hourly ammonia consumption of the SNCR denitrification system decreased by 106.79 kg / h, and the ammonia consumption per ton of clinker decreased by 0.47 kg / t·cl.

[0037] Monitoring results: The CO concentration at the denitrification furnace outlet (detection point 7) increased by 120 ppm compared to the blank test; the NO concentration at the decomposition furnace outlet (detection point 11) increased... X A 15% reduction in concentration at the chimney outlet NO X Stable at 94.50 mg / m³ 3 .

[0038] Example 2: Experiment on the addition of medium-calorific-value liquid hazardous waste

[0039] Hazardous waste preparation: Select liquid hazardous waste with a calorific value of 4500-6000 kcal / kg, and atomize it with 0.5 MPa compressed air through a spray gun, with the droplet size controlled at 50-100 μm;

[0040] Dosing control: At dosing point 4 of the denitrification furnace, at a rate of 1.0m... 3 The spray gun is injected at a flow rate of / h, with an angle of 30° between the spray gun and the direction of flue gas flow.

[0041] Parameter adjustment:

[0042] Coal powder substitution: The amount of coal powder used at point 2 of the denitrification furnace was reduced by 5.28 kg / t·cl. (actual coal consumption), and the temperature of the denitrification furnace was maintained at 800℃-900℃;

[0043] Ammonia adjustment: Based on the detection point 14NO x Concentration (95.76 mg / m³) 3 The average hourly ammonia consumption decreased by 66.02 kg / h, and the ammonia consumption per ton of clinker decreased by 0.29 kg / t·cl.

[0044] Monitoring results: The CO concentration in the middle of the denitrification furnace (detection point 5) increased by 80 ppm compared with the blank test, and the NO concentration at the chimney outlet increased. X Stable at 95.76 mg / m³ 3 .

[0045] Example 3: Blank Control Experiment

[0046] Without the addition of liquid hazardous waste, the pulverized coal consumption at point 2 of the denitrification furnace is 157.97 kg / t·cl. (actual coal consumption), the hourly average ammonia water consumption of the SNCR system is 560.38 kg / h, the ammonia water consumption per ton of clinker is 2.45 kg / t·cl., and the NO at the chimney outlet is... X Concentration 94.49 mg / m³ 3 .

[0047] Results analysis:

[0048] During the treatment of two types of liquid hazardous waste with calorific values ​​ranging from 4500-6000 kcal / kg and 10000-12000 kcal / kg respectively at appropriate locations in a denitrification furnace, the flow rate was controlled at 0.5-1.2 m³ / kg. 3 Within the range of / h, compared with the operating condition without the addition of liquid hazardous waste, when the NO in the flue gas discharged into the atmosphere... X The concentration was controlled at 90-100 mg / m³. 3 Within the same range, comparing Examples 1 and 2 with the blank test, using the aforementioned liquid hazardous waste with a certain calorific value can reduce the actual coal consumption for clinker combustion by 5.28–10.68 kg / t·cl., which translates to a standard coal consumption of 4.53–9.15 kgce / t·cl. The reduction in actual coal consumption per ton of clinker depends on the calorific value of the liquid hazardous waste and the amount added. The higher the calorific value of the liquid hazardous waste and the higher the amount added, the more significant the reduction in actual coal consumption. The reduction in coal consumption per ton of clinker is significant. Experimental data are shown in Table 1. Before and after the addition of the calorific value liquid hazardous waste, when the NO in the flue gas emitted into the atmosphere... X The content was controlled at 90-100 mg / m³. 3 When the calorific value of the liquid hazardous waste within the above-mentioned range is specified, adding the liquid hazardous waste within the specified range can reduce the average hourly ammonia consumption by 24.69 kg / h to 106.79 kg / h. Converted to ammonia consumption per ton of clinker, this translates to a reduction of 0.11 to 0.47 kg / t·cl. The reduction in ammonia consumption per ton of clinker is significant, as shown in Table 2. This invention, by adding liquid hazardous waste with a specified calorific value, ensures that NO... X Under the premise of meeting emission standards, the coal consumption and ammonia water consumption were significantly reduced, verifying the effectiveness of the technical solution.

[0049]

[0050]

[0051] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A process for energy saving and consumption reduction in cement industry, characterized in that: It comprises the following steps: Step one, hot value liquid hazardous waste adding preparation: select liquid hazardous waste with heat value in the range of 4500-6000kcal / kg or 10000-12000kcal / kg, and fully atomize it by compressed air and special spray gun; Step two, injection position selection and control: at the injection point of liquid hazardous waste with heat value in the denitrogenation furnace system, the atomized liquid hazardous waste is injected into the denitrogenation furnace at a flow rate of 0.5-1.2 m 3 / h Step 3: Adjust operating parameters: Based on the temperature and NO conditions within the denitrification furnace system... X To reduce the concentration of pulverized coal and decrease the amount of pulverized coal injected into the denitrification furnace, the temperature of the denitrification furnace system should be kept stable. Simultaneously, based on the NO concentration at the detection points... X Based on the concentration data, adjust the ammonia water dosage of the SNCR denitrification system to ensure that the NO concentration in the flue gas at the chimney outlet is within acceptable limits. X Concentration controlled at 90-100 mg / m³ 3 Within the range; Step four, effect monitoring: through the detection points set in the kiln tail flue, the middle of denitration furnace, the outlet of denitration furnace, the outlet of decomposition furnace, the outlet of preheater and the outlet of chimney, the concentration of gas components such as NO X , CO and the temperature, pressure parameters in the flue gas are monitored in real time, and the energy-saving denitration effect is verified.

2. A process for energy saving and consumption reduction in cement industry as claimed in claim 1 wherein: In the step one, the particle size of the atomized liquid hazardous waste is controlled in the range of 50-150μm to ensure sufficient combustion in the denitration furnace.

3. A process for energy saving and consumption reduction in cement industry as claimed in claim 1 wherein: In the step two, the hot value liquid hazardous waste adding point is located in the downstream area of the coal injection point of the denitration furnace system, and the spray direction of the spray gun forms an angle of 30°-60° with the flue gas flow direction in the denitration furnace.

4. A process for energy conservation in cement industry as claimed in claim 1 wherein: In the third step, the reduction range of the coal powder injection amount is matched with the heat value and the addition amount of the liquid hazardous waste, when the heat value of the liquid hazardous waste is 10000-12000kcal / kg and the addition amount is 0.8-1.2m 3 / h, the reduction range of the coal powder amount is 6.84-10.68kg / t·cl.

5. A process for energy conservation in cement industry as claimed in claim 1 wherein: The ammonia water consumption of the SNCR denitration system in step three is adjusted according to the online monitoring data at the chimney outlet. When the NO X concentration is lower than 90 mg / m 3 , the ammonia water consumption is reduced; when the NO 3 concentration is higher than 100 mg / m , the ammonia water consumption is increased, so that the ammonia water consumption per ton of clinker is reduced by 0.11-0.47 kg / t·cl.

6. A process for energy conservation in cement industry as claimed in claim 1 wherein the process is characterized by: In the step four, the monitoring frequency of each detection point is not less than 1 time / hour, and the detection data is transmitted to the central control system in real time to guide the working condition parameter adjustment.

7. A process for energy conservation in cement industry as claimed in claim 1 wherein the said process is characterized by: The process technology is suitable for the cement kiln co-processing hazardous waste production line with denitration furnace and SNCR denitration system, and can also be applied to industrial kiln systems such as power plants, smelters and the like which need to reduce the NO X emissions of flue gas.

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