Calcium chloride is used to produce positive pressure furnace and control method

Abstract

The application discloses a kind of application calcium chloride production positive pressure stove and control method, it is related to calcium chloride granulation technical field, including hot blast furnace and granulation tower, hot blast furnace includes burner, hot blast furnace end plate assembly, hot blast furnace shell assembly and hot blast furnace inner shell assembly, wind cooling jacket is formed between hot blast furnace shell assembly and hot blast furnace inner shell assembly, multiple cyclone barrel is arranged in hot blast furnace inner shell assembly, expansion joint is provided at the outlet of hot blast furnace, and the end of expansion joint away from hot blast furnace is connected with heat-resistant pipeline.The application provides a kind of application calcium chloride production positive pressure stove and control method, solves the problem that the equipment failure rate is high, energy consumption is large, and maintenance cost is high in prior art calcium chloride granulation hot blast system due to being equipped with high-temperature fan and high-temperature regulating air valve;Hot blast furnace is provided with wind cooling jacket, multiple cyclone barrel and cyclone sheet, and dilution air passes through wind cooling jacket, and after entering hot blast furnace hearth from hot blast furnace head part stage, is mixed with high-temperature combustion flue gas.

Description

Technical Field

[0001] This invention relates to the field of calcium chloride granulation technology, specifically to a positive pressure furnace for calcium chloride production and its control method. Background Technology

[0002] In the calcium chloride production process, granulation is one of the key steps. Traditional calcium chloride granulation processes typically use granulation towers, where high-temperature hot air exchanges heat with atomized calcium chloride droplets, causing the droplets to cool and crystallize into granules as they descend.

[0003] The traditional hot air system configuration for granulation towers is as follows: a hot air furnace generates high-temperature hot air, which is then pressurized by a high-temperature fan and delivered to the top of the granulation tower. To ensure stable pressure and flow rate of the hot air entering the tower, the system also needs to be equipped with a high-temperature regulating valve for air volume adjustment.

[0004] This traditional structure has the following inherent defects:

[0005] 1. The equipment operates under harsh conditions and has a high failure rate. The high-temperature fan and high-temperature regulating valve work in a high-temperature environment of 650℃-800℃ for a long time. The equipment materials have high requirements and are very prone to failure due to high-temperature oxidation, thermal deformation or bearing failure, which can lead to unplanned shutdowns of the production line.

[0006] 2. High energy consumption: As a high-power electrical device, the high-temperature fan consumes a large amount of electricity during long-term operation. At the same time, the high-temperature regulating valve generates throttling losses during regulation, further increasing system energy consumption.

[0007] 3. High maintenance costs: High-temperature fans and their associated high-temperature valves are expensive equipment, and the short maintenance cycle and frequent replacement of spare parts lead to increased production costs.

[0008] 4. High levels of nitrogen oxides in flue gas: High-temperature flue gas from the hot blast stove outlet mixes with dilution air at the tail end of the stove. Firstly, the high temperature inside the hot blast stove easily leads to the formation of temperature-dependent nitrogen oxides in the combustion flue gas. When burning natural gas, the nitrogen oxide content in the exhaust gas reaches 200 mg / Nm³. 3 The emissions cannot meet the standards.

[0009] 5. Uneven hot air temperature: The high-temperature flue gas at the outlet of the hot air furnace mixes with the dilution air at the tail end of the hot air furnace. Before entering the granulation tower, due to the short distance, the mixing time and space are insufficient, making it difficult to mix evenly. Summary of the Invention

[0010] The purpose of this invention is to address the above-mentioned problems by providing a positive pressure furnace and control method for calcium chloride production. This solves the problems of high equipment failure rate, high energy consumption, and high maintenance cost in existing calcium chloride granulation hot air systems due to the use of high-temperature fans and high-temperature regulating valves. The hot air furnace is equipped with an air-cooled jacket, multi-stage cyclone separators, and swirl vanes. The dilution air passes through the air-cooled jacket and enters the furnace chamber from the head of the hot air furnace in stages, where it mixes with the high-temperature combustion flue gas. This ensures that the outer surface temperature of the hot air furnace does not exceed the ambient temperature +40°C after the dilution air is cooled. Because the dilution air is mixed with the high-temperature combustion flue gas in stages, it can effectively control the generation of temperature-dependent nitrogen oxides.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A positive pressure furnace for calcium chloride production includes a hot blast stove and a granulation tower. The hot blast stove includes a burner, a hot blast stove end plate assembly, a hot blast stove outer shell assembly, and a hot blast stove inner shell assembly. The hot blast stove outer shell assembly and the hot blast stove inner shell assembly form an air-cooled jacket. A multi-stage cyclone separator is installed inside the hot blast stove inner shell assembly. An expansion joint is provided at the outlet of the hot blast stove. The end of the expansion joint away from the hot blast stove is connected to a heat-resistant pipe. The end of the heat-resistant pipe away from the hot blast stove is connected to the hot air inlet of the granulation tower. The outlet of the dilution fan is connected to a dilution air duct. The other end of the dilution air duct is connected to the air inlet of the hot blast stove air-cooled jacket. The outlet of the combustion air fan is connected to a combustion air duct. The other end of the combustion air duct is connected to the combustion air inlet of the burner. The burner is fixed on the hot blast stove end plate assembly. A dilution air regulating device is provided on the hot blast stove end plate assembly.

[0013] As a further improvement to the above solution, the hot air furnace is a high-pressure hot air furnace, capable of withstanding a pipeline hot air pressure of 7.5-9 kPa.

[0014] As a further improvement to the above solution, a multi-stage cyclone separator is provided inside the hot air furnace shell assembly.

[0015] As a further improvement to the above solution, the hot air furnace end plate assembly includes an outer end plate and an inner end plate, with insulation cotton filled between the outer end plate and the inner end plate. The burner is fixed on the hot air furnace end plate assembly, and four dilution air regulating devices are evenly distributed in the circumferential direction of the burner.

[0016] As a further improvement to the above solution, the dilution air regulating device consists of an adjusting rod, a handle, an adjusting rod sleeve, a dilution air baffle ring, and a locking nut. The dilution air baffle ring is located at the end of the adjusting rod, and the handle is located at the end of the adjusting rod away from the dilution air baffle ring.

[0017] As a further improvement to the above solution, the adjusting rod is slidably disposed inside the adjusting rod sleeve. When the adjusting rod is pushed or pulled, the gap between the dilution wind baffle ring and the inner wall of the first-stage cyclone increases or decreases.

[0018] As a further improvement to the above solution, an explosion-proof valve assembly and lifting lugs are provided on the upper part of the hot blast furnace shell assembly, and support feet are provided on the bottom of the hot blast furnace shell assembly.

[0019] A control method for a hot air system used in calcium chloride granulation includes the following steps:

[0020] Step A: Set the target hot air pressure and target hot air temperature;

[0021] Step B: Change the supply and pressure of combustion air by adjusting the operating frequency or guide vane opening of the combustion fan;

[0022] Step C: Based on the preset temperature-pressure coupling control logic, the fuel supply is adjusted synchronously to ensure that the hot air temperature remains within the set range when the pressure changes;

[0023] Step D: Based on the detected levels of nitrogen oxides, CO, and oxygen in the combustion flue gas, the push-pull handle moves the dilution air baffle ring via the adjusting rod. This increases or decreases the gap between the dilution air baffle ring and the inner wall of the first-stage cyclone separator, adjusting the amount of cooling air entering the root of the combustion flame. This ensures that the central flame temperature is reduced without flameout, achieving low-NOx combustion. When the nitrogen oxides in the combustion flue gas are less than 50 mg / Nm³... 3 Simply tighten the lock nut.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. To solve the problems of high equipment failure rate, high energy consumption and high maintenance cost caused by the high temperature fan and high temperature regulating valve in the existing calcium chloride granulation hot air system, a 4-stage cyclone separator is set up to mix the dilution air and high temperature flue gas evenly. A dilution air regulating device is also set up to ensure low-NOx safe and stable combustion.

[0026] 2. Simplified system structure and improved reliability: The high-temperature fan and high-temperature regulating valve, two vulnerable components under high-temperature conditions, have been eliminated, significantly simplifying the hot air system structure. With the elimination of high-temperature rotating machinery and high-temperature regulating mechanisms, system operational stability is significantly improved, the number of potential failure points is reduced, and the risk of unplanned shutdowns is greatly reduced.

[0027] 3. The hot blast stove is equipped with an air-cooled jacket. The dilution air passes through the air-cooled jacket and enters the hot blast stove in stages from the head of the hot blast stove to mix with the high-temperature combustion flue gas, so that the outer surface temperature of the hot blast stove does not exceed the ambient temperature +40℃.

[0028] 4. Significantly reduced energy consumption: The high-power high-temperature fan motor is eliminated, thus eliminating the energy consumption of the original high-temperature fan operation and the throttling losses of the high-temperature air valve. Hot air parameters can be controlled simply by adjusting the combustion fan, a room-temperature device, resulting in a significant reduction in the total energy consumption of the system.

[0029] 5. Since the dilution air is mixed with the high-temperature flue gas in a staged swirl, it can mix the dilution air and the high-temperature flue gas in a swirl and can effectively control the generation of temperature-dependent nitrogen oxides.

[0030] 6. Based on the detection of nitrogen oxides, CO and oxygen content in the combustion flue gas, the push-pull handle moves the dilution air baffle ring through the adjustment rod, which can adjust the cooling air volume of the dilution air entering the root of the combustion flame, so as to reduce the temperature of the central flame without flameout and achieve low-NOx combustion.

[0031] 7. Reduced equipment investment and maintenance costs: High-temperature fans and high-temperature alloy valves are expensive; eliminating these devices reduces initial equipment investment. Simultaneously, system simplification reduces daily maintenance workload and spare parts costs.

[0032] 8. Optimized control performance: Front-end adjustment via combustion fan results in faster response and more direct control. This avoids the inaccurate control issues caused by the lag or jamming of high-temperature dampers in the original system. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the main structure of the present invention.

[0034] Figure 2 for Figure 1 A magnified view of a portion of location A in the middle.

[0035] Figure 3 This is a schematic diagram of the multi-stage cyclone separator and swirl vanes in this invention.

[0036] The text labels in the diagram represent: 1. Burner; 2. Hot air furnace end plate assembly; 3. Hot air furnace outer shell assembly; 4. Hot air furnace inner shell assembly; 5. Multi-stage cyclone separator; 6. Explosion-proof valve assembly; 7. Lifting lug; 8. Expansion joint; 9. Heat-resistant pipe; 10. Granulation tower; 11. Dilution fan; 12. Dilution duct; 13. Support leg; 14. Combustion duct; 15. Combustion fan; 201. Locking nut; 202. Handle; 203. Sleeve; 204. Outer end plate; 205. Insulation cotton; 206. Inner end plate; 207. Adjusting rod; 208. Dilution air baffle ring; 501. Primary cyclone separator; 502. Secondary cyclone separator; 503. Tertiary cyclone separator; 504. Quaternary cyclone separator; 505. Swirl vane. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0038] Example 1:

[0039] like Figures 1-3 As shown, the specific solution of this embodiment is as follows: a positive pressure furnace for calcium chloride production includes a hot blast stove and a granulation tower 10. The hot blast stove includes a burner 1, a hot blast stove end plate assembly 2, a hot blast stove outer shell assembly 3, and a hot blast stove inner shell assembly 4. The hot blast stove outer shell assembly 3 and the hot blast stove inner shell assembly 4 form an air-cooled jacket. A multi-stage cyclone 5 is provided inside the hot blast stove inner shell assembly 4. An expansion joint 8 is provided at the outlet of the hot blast stove. The end of the expansion joint 8 away from the hot blast stove is connected to a heat-resistant pipe 9. The end of the heat-resistant pipe 9 away from the hot blast stove is connected to the hot air inlet of the granulation tower 10. The outlet of the dilution fan 11 is connected to a dilution air duct 12. The other end of the dilution air duct 12 is connected to the air inlet of the hot blast stove air-cooled jacket. The outlet of the combustion fan 15 is connected to a combustion air duct 14. The other end of the combustion air duct 14 is connected to the combustion air inlet of the burner 1. The burner 1 is fixed on the hot blast stove end plate assembly 2. A dilution air regulating device is provided on the hot blast stove end plate assembly 2.

[0040] The technical solution of this embodiment 1 differs from traditional technology. Instead of the traditional method of the dilution air entering the furnace from the tail end via an air-cooled jacket, it enters from the head end of the hot blast stove. The multi-stage cyclone separator 5 has a gradually expanding 3-5 stage cylindrical structure. The multi-stage cyclone separator 5 includes a primary cyclone separator 501, a secondary cyclone separator 502, a tertiary cyclone separator 503, a quaternary cyclone separator 504, and swirl vanes 505. This facilitates the mixing of the dilution air with the high-temperature combustion flue gas within the hot blast stove, from the hot blast stove outer shell assembly 3 to the multi-stage cyclone separator 5. This helps reduce the generation of temperature-dependent nitrogen oxides during combustion, and the nitrogen oxide emissions can be controlled at 50 mg / Nm³. 3 Furthermore, in traditional hot blast stoves, the dilution air inlet enters the furnace directly at the tail end of the stove, forming an air curtain at the outlet, which increases the resistance to hot air.

[0041] Example 2:

[0042] The difference from Example 1 is that the hot air furnace is a high-pressure hot air furnace, which can withstand a pipeline hot air pressure of 7.5-9 kPa.

[0043] The hot air furnace is a combustion furnace with high output air pressure. Its structure is reinforced and has good sealing performance. It can generate 7.5-9KPa hot air to overcome the pipeline resistance. The hot air outlet of the hot air furnace is directly connected to the hot air inlet at the bottom of the granulation tower 10 through the heat-resistant pipe 9. No high-temperature fan or high-temperature regulating valve is installed on the entire pipeline.

[0044] Example 3:

[0045] The difference from Embodiment 1 is that a multi-stage cyclone separator 5 is provided inside the hot air furnace shell assembly 3.

[0046] The hot air furnace end plate assembly 2 includes an outer end plate 204 and an inner end plate 206. Insulation cotton 205 is filled between the outer end plate 204 and the inner end plate 206. The burner 1 is fixed on the hot air furnace end plate assembly 2. Four dilution air regulating devices are evenly distributed in the circumference of the burner 1.

[0047] The hot blast stove is equipped with a dilution fan 11 and a combustion fan 15. The combustion fan 15 is a normal temperature variable frequency high pressure fan, which is used to provide combustion air to the hot blast stove. The dilution fan 11 is a normal temperature variable frequency high pressure fan. After the normal temperature air passes through the air-cooled jacket, it is mixed with the high temperature flue gas from the furnace head through the multi-stage cyclone 5 to obtain hot air at a constant temperature.

[0048] The dilution air regulating device consists of an adjusting rod 207, a handle 202, an adjusting rod sleeve 203, a dilution air baffle ring 208, and a locking nut 201. The dilution air baffle ring 208 is located at the end of the adjusting rod 207, and the handle 202 is located at the end of the adjusting rod 207 away from the dilution air baffle ring 208.

[0049] The adjusting rod 207 is slidably disposed within the adjusting rod sleeve 203. When the adjusting rod 207 is pushed or pulled, the gap between the dilution air baffle ring 208 and the inner wall of the multi-stage cyclone separator 5 increases or decreases. The push-pull handle 202 moves the dilution air baffle ring 208 through the adjusting rod 207. The increase or decrease in the gap between the dilution air baffle ring 208 and the inner wall of the multi-stage cyclone separator 5 can adjust the cooling air volume of the dilution air entering the root of the combustion flame, ensuring that the central flame temperature is reduced without flameout, thus achieving low-NOx combustion. When the NOx in the combustion flue gas is less than 50 mg / Nm³, 3 Simply tighten the locking nut 201.

[0050] An explosion-proof valve assembly 6 and a lifting lug 7 are installed on the upper part of the hot blast furnace outer shell assembly 3, and a support foot 13 is installed at the bottom of the hot blast furnace outer shell assembly 3.

[0051] A control method for a hot air system used in calcium chloride granulation includes the following steps:

[0052] Step A: Set the target hot air pressure and target hot air temperature;

[0053] Step B: Change the supply and pressure of combustion air by adjusting the operating frequency or guide vane opening of the combustion fan 15;

[0054] Step C: Based on the preset temperature-pressure coupling control logic, the fuel supply is adjusted synchronously to ensure that the hot air temperature remains within the set range when the pressure changes;

[0055] Step D: Based on the detected nitrogen oxide, CO, and oxygen content in the combustion flue gas, the push-pull handle 202 moves the dilution wind baffle ring 208 via the adjusting rod 207. This increases or decreases the gap between the dilution wind baffle ring 208 and the inner wall of the multi-stage cyclone separator 5, adjusting the cooling airflow into the root of the combustion flame. This ensures that the central flame temperature is reduced without flameout, achieving low-NOx combustion. When the nitrogen oxide content in the combustion flue gas is less than 50 mg / Nm³... 3 Simply tighten the locking nut 201.

[0056] The specific working principle of this invention is as follows:

[0057] The temperature of the hot air entering the bottom of the granulation tower 10 needs to be relatively stable. Changes in load require adjustments to the hot air volume and pressure. When adjusting the hot air parameters entering the granulation tower 10, the system does not throttle the hot air, but adjusts the supply of combustion air by changing the frequency of the combustion fan 15 and the dilution fan 11.

[0058] Pressure regulation: When it is necessary to increase the hot air pressure inside the granulation tower 10 to improve the suspension state of atomized droplets, the frequency of the combustion fan 15 is increased to increase the combustion air pressure. The pressure inside the hot air furnace increases accordingly, which in turn directly increases the static pressure of the hot air at the inlet of the granulation tower 10 through the heat-resistant pipe 9.

[0059] Temperature regulation: As the gas load changes, the combustion air changes accordingly based on the set air-fuel ratio. The cooling air required for the high-temperature flue gas generated by combustion also changes accordingly. While adjusting the combustion air fan 15, the system also adjusts the dilution air fan 11 to keep the hot air temperature stable within the range required by the process (usually 600℃-700℃).

[0060] By eliminating the traditional high-temperature fan and high-temperature regulating valve, this system avoids the problem of easy damage to high-temperature components. Actual production testing shows that the system using this invention extends the hot air system's operating time by more than 30% compared to traditional systems, and saves approximately 150-200 kWh of electricity per hour (depending on the original high-temperature fan's power). The maintenance cycle is extended from once a month to once every six months, resulting in significant economic benefits.

[0061] It should be noted that, in this document, the terms "including," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A positive pressure furnace for producing calcium chloride, comprising a hot blast stove and a granulation tower (10), characterized in that, The hot blast stove includes a burner (1), a hot blast stove end plate assembly (2), a hot blast stove outer shell assembly (3), and a hot blast stove inner shell assembly (4). The hot blast stove outer shell assembly (3) and the hot blast stove inner shell assembly (4) form an air-cooled jacket. The hot blast stove inner shell assembly (4) is equipped with a multi-stage cyclone separator (5). The hot blast stove outlet is equipped with an expansion joint (8). The end of the expansion joint (8) away from the hot blast stove is connected to a heat-resistant pipe (9). The end of the heat-resistant pipe (9) away from the hot blast stove is connected to the hot air inlet of the granulation tower (10). The outlet of the dilution fan (11) is connected to the dilution air duct (12). The other end of the dilution air duct (12) is connected to the air inlet of the hot blast stove air-cooled jacket. The outlet of the combustion fan (15) is connected to the combustion air duct (14). The other end of the combustion air duct (14) is connected to the combustion air inlet of the burner (1). The burner (1) is fixed on the hot blast stove end plate assembly (2). A dilution air regulating device is provided on the hot blast stove end plate assembly (2).

2. The positive pressure furnace for calcium chloride production according to claim 1, characterized in that, The hot air furnace is a high-pressure hot air furnace, capable of withstanding 7.5-9 kPa pipeline hot air pressure.

3. A positive pressure furnace for calcium chloride production according to claim 1, characterized in that, The hot air furnace shell assembly (3) is equipped with a multi-stage cyclone separator (5).

4. A positive pressure furnace for calcium chloride production according to claim 1, characterized in that, The hot air furnace end plate assembly (2) includes an outer end plate (204) and an inner end plate (206). Insulation cotton (205) is filled between the outer end plate (204) and the inner end plate (206). The burner (1) is fixed on the hot air furnace end plate assembly (2). Four dilution air regulating devices are evenly distributed in the circumferential direction of the burner (1).

5. A positive pressure furnace for calcium chloride production according to claim 4, characterized in that, The dilution air regulating device consists of an regulating rod (207), a handle (202), a regulating rod sleeve (203), a dilution air baffle ring (208), and a locking nut (201). The dilution air baffle ring (208) is located at the end of the regulating rod (207), and the handle (202) is located at the end of the regulating rod (207) away from the dilution air baffle ring (208).

6. A positive pressure furnace for calcium chloride production according to claim 5, characterized in that, The adjusting rod (207) is slidably disposed inside the adjusting rod sleeve (203). When the adjusting rod (207) is pushed or pulled, the gap between the dilution wind baffle ring (208) and the inner wall of the first-stage cyclone (501) increases or decreases.

7. A positive pressure furnace for calcium chloride production according to claim 1, characterized in that, The hot blast furnace shell assembly (3) is provided with an explosion-proof valve assembly (6) and a lifting lug (7) on the upper part, and a support foot (13) is provided at the bottom of the hot blast furnace shell assembly (3).

8. A control method for a positive pressure furnace used in calcium chloride production as described in any one of claims 1-7, characterized in that, Includes the following steps: Step A: Set the target hot air pressure and target hot air temperature; Step B: Change the supply and pressure of combustion air by adjusting the operating frequency or guide vane opening of the combustion fan (15); Step C: Based on the preset temperature-pressure coupling control logic, the fuel supply is adjusted synchronously to ensure that the hot air temperature remains within the set range when the pressure changes; Step D: Based on the detected nitrogen oxide, CO, and oxygen content in the combustion flue gas, the push-pull handle (202) moves the dilution wind baffle ring (208) via the adjusting rod (207). The gap between the dilution wind baffle ring (208) and the inner wall of the first-stage cyclone (5) increases or decreases, which is used to adjust the cooling air volume of the dilution air entering the root of the combustion flame, ensuring that the temperature of the central flame is reduced without flameout, thus achieving low-NOx combustion. When the nitrogen oxide content in the combustion flue gas is less than 50 mg / Nm³, 3 Simply tighten the lock nut (201).

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