A powdered limestone suspension calcination system with waste gas treatment function

Abstract

A powdered limestone suspension calcination system with waste gas treatment function belongs to the fields of limestone resource processing technology and industrial waste gas treatment. It includes a feeding unit, a calcination unit, a cooling unit, a product bin, and a tail gas treatment unit. The discharge end of the feeding unit is connected to the feed end of the calcination unit, the discharge end of the calcination unit is connected to the feed end of the cooling unit, and the discharge end of the cooling unit is connected to the product bin. The air inlet of the feeding unit is connected to the air outlet of the calcination unit, the air outlet of the feeding unit is connected to the air inlet of the tail gas treatment unit, and the air outlet of the cooling unit is connected to the air inlet of the tail gas treatment unit. The system provided by this invention can realize the calcination of limestone of all particle sizes, introduces a heat recovery system and a waste gas treatment system, reducing energy consumption and production costs; after dust removal, cooling, and treatment, the waste gas has reduced environmental impact and meets the requirements of sustainable development.

Description

Technical Field

[0001] This invention belongs to the field of limestone resource processing technology and industrial waste gas treatment, specifically relating to a powdered limestone suspension calcination system with waste gas treatment function. Background Technology

[0002] Lime is an important chemical raw material, widely used in construction, metal smelting, chemical industry, agriculture and environmental protection.

[0003] High-temperature calcination of limestone is the primary method for producing lime. At high temperatures, calcium carbonate, the main component of limestone, undergoes a decomposition reaction: CaCO3(s) = CaO(s) + CO2(g). On one hand, the decomposition of limestone requires a large amount of heat, which in traditional processes typically comes from fossil fuels such as coal, leading to high carbon dioxide emissions. On the other hand, besides producing quicklime (CaO), the decomposition of limestone also releases CO2, a source of carbon emissions. Therefore, lime production is a high-energy-consuming and high-emission industry. Under the dual carbon environment (carbon dioxide, carbon emissions, and carbon emissions), the lime industry faces significant challenges and opportunities.

[0004] Patent CN107673637A provides a method for calcining powdered lime using a suspension calcination device. Compared with traditional vertical kilns, this method significantly shortens the limestone decomposition time. However, the fuel used in this method is still traditional fossil fuel, resulting in high energy consumption. Furthermore, the exhaust gas only undergoes simple dust removal without an effective exhaust gas treatment device. Patent CN109467323B provides a lime suspension calcination process device. This device is equipped with a multi-stage preheating system and a multi-stage cooling system, allowing sufficient contact and reaction time for both raw materials and airflow, thus enhancing the calcination effect. However, the exhaust gas is only subjected to simple dust removal before being discharged into the environment, putting considerable pressure on the environment.

[0005] In general, the main industrial equipment for calcining limestone currently includes vertical kilns, double-chamber kilns, and rotary kilns. During the calcination process, these devices or systems can only process limestone particles larger than 20mm. Limestone smaller than 20mm is either used for road paving or discarded, resulting in a waste of limestone resources. Furthermore, these devices often require coal to maintain a stable calcination temperature, leading to high energy consumption. The waste gas generated during calcination is either simply dusted or directly discharged into the atmosphere without effective environmental treatment, placing a significant burden on the environment. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a powdered limestone suspension calcination system with waste gas treatment capabilities. The system incorporates a suspension calcination furnace capable of processing limestone resources smaller than 20mm, and integrates a dust removal system and a waste gas treatment system to harmlessly treat the waste gas generated during calcination. The raw limestone ore is crushed to less than 1mm. After preheating and dispersion, the fine limestone powder is fed into the suspension calcination furnace for calcination. The calcined product is separated, cooled, and transferred to a product silo by a transport device. The high-temperature flue gas, after heat recovery and utilization, undergoes dust removal and cooling before entering the waste gas processor. Once emission standards are met, it is discharged through a chimney.

[0007] A powdered limestone suspension calcination system with waste gas treatment function includes a feeding unit, a calcination unit, a cooling unit, a product bin, and a tail gas treatment unit. The discharge end of the feeding unit is connected to the feed end of the calcination unit, the discharge end of the calcination unit is connected to the feed end of the cooling unit, and the discharge end of the cooling unit is connected to the product bin. The air inlet of the feeding unit is connected to the air outlet of the calcination unit, the air outlet of the feeding unit is connected to the air inlet of the tail gas treatment unit, and the air outlet of the cooling unit is connected to the air inlet of the tail gas treatment unit.

[0008] The feeding unit includes a feeding hopper, a loss-in-weight scale, a screw feeder, and a preheater. The feeding hopper has a discharge port at its lower end, which is connected to the inlet of the loss-in-weight scale. The discharge port of the loss-in-weight scale is connected to the inlet of the screw feeder. The preheater has an inlet and an exhaust port at its upper part. The inlet of the preheater is connected to the discharge port of the screw feeder. The preheater has an air inlet on one side and a ore discharge port at its bottom. A powder dispersion device is installed at the ore discharge port.

[0009] The calcination unit includes a suspension calcination furnace, a cyclone separator, and a burner. A feed port is provided on one side of the suspension calcination furnace, which is connected to the discharge port at the bottom of the preheater. The other side of the suspension calcination furnace is connected to the upper part of the cyclone separator, and an air inlet is provided at the lower part, which is connected to the burner. A discharge port is provided at the bottom. An exhaust port is provided above the cyclone separator, which is connected to the air inlet of the preheater. A discharge port is provided below the cyclone separator.

[0010] The cooling unit includes a first cooler and a first Roots blower. The upper part of the first cooler is provided with an exhaust port and two feed ports. The first feed port of the first cooler is connected to the discharge port of the cyclone separator, and the second feed port of the first cooler is connected to the discharge port at the bottom of the suspension calcining furnace. An air inlet is provided on one side of the lower part of the first cooler and is connected to the first Roots blower. The bottom of the first cooler is provided with a discharge port that is connected to the product hopper.

[0011] The exhaust gas treatment unit includes a ceramic dust collector, a first ash trough, a second cooler, a second Roots blower, a bag filter dust collector, a second ash trough, a third cooler, a third Roots blower, an exhaust gas processor, and a chimney. The ceramic dust collector has two air inlets on one side; the first air inlet is connected to the exhaust port of the preheater, and the second air inlet is connected to the exhaust port of the first cooler. An exhaust port is located on the other side of the ceramic dust collector and is connected to the air inlet at the top of the second cooler. A discharge port is located at the bottom of the ceramic dust collector. The first ash trough is connected to the second Roots blower; the second cooler has an air inlet on one side, connected to the second Roots blower, and an exhaust port at the bottom, connected to the air inlet at the top of the bag filter; the bag filter has an exhaust port on one side, connected to the air inlet of the third cooler, and a discharge port at the bottom of the bag filter, connected to the second ash trough; the third cooler has an air inlet on one side, connected to the third Roots blower, and an exhaust port at the bottom of the third cooler, connected to the air inlet of the exhaust gas processor; the exhaust gas processor has an exhaust port at the bottom, connected to the chimney.

[0012] The feeding silo is equipped with a drying function, through which the limestone fine powder is dried.

[0013] The powder dispersing device is used to disperse limestone fine powder.

[0014] The burner is fueled by natural gas or liquefied petroleum gas.

[0015] The first cooler adopts a single-stage structure or a multi-stage series structure.

[0016] The exhaust gas processor is used to collect, compress, and store CO2 in the exhaust gas, and also to treat NO in the exhaust gas. x gas.

[0017] Compared with the prior art, the beneficial effects and innovations of the present invention are as follows:

[0018] 1. The system provided by this invention incorporates a heat recovery system and a waste gas treatment system. The heat recovery system effectively recovers and utilizes the high-temperature waste heat generated during the calcination process, reducing energy consumption and production costs. After dust removal, cooling, and treatment, the waste gas exhibits reduced CO2 and NO emissions. x Gas emissions are reduced, thus minimizing environmental impact and meeting the requirements of sustainable development.

[0019] 2. The feed particle size of the suspension calcining furnace is less than 1mm. Whether it is medium-to-large-diameter (40-300mm) limestone or small-diameter limestone (<20mm), it can be crushed to less than 1mm, and the calcination of limestone of all particle sizes can be realized.

[0020] 3. The suspension calcination system has high thermal efficiency, requiring less fuel under the same production conditions compared to traditional processes, thus reducing CO2 and other pollutant emissions during fuel combustion. Simultaneously, because the limestone powder is suspended in the airflow and heated uniformly, it ensures complete reaction of the limestone, reducing unburned residues and further decreasing the pollutant content in the exhaust gas. Attached Figure Description

[0021] Figure 1 A schematic diagram of a powdered limestone suspension calcination system with waste gas treatment function according to the present invention;

[0022] Among them: 1-feeding bin, 2-loss-in-weight scale, 3-screw feeder, 4-preheater, 5-suspension calcining furnace, 6-cyclone separator, 7-burner, 8-first cooler, 9-first Roots blower, 10-product bin, 11-ceramic dust collector, 12-first ash trough, 13-second cooler, 14-second Roots blower, 15-bag filter dust collector, 16-second ash trough, 17-third cooler, 18-third Roots blower, 19-exhaust gas processor, 20-chimney. Detailed Implementation

[0023] Example 1

[0024] A schematic diagram of a powdered limestone suspension calcination system with waste gas treatment function is shown below. Figure 1 As shown, the system includes a feeding unit, a calcination unit, a cooling unit, a product bin 10, and a tail gas treatment unit. The discharge end of the feeding unit is connected to the feed end of the calcination unit, the discharge end of the calcination unit is connected to the feed end of the cooling unit, and the discharge end of the cooling unit is connected to the product bin 10. The air inlet of the feeding unit is connected to the air outlet of the calcination unit, the air outlet of the feeding unit is connected to the air inlet of the tail gas treatment unit, and the air outlet of the cooling unit is connected to the air inlet of the tail gas treatment unit.

[0025] The feeding unit includes a feeding bin 1, a loss-in-weight scale 2, a screw feeder 3, and a preheater 4. The feeding bin 1 is a feeding bin with a drying function to dry the limestone fine powder therein and keep it in a dry state. The lower end of the feeding bin 1 is provided with a discharge port, which is connected to the inlet of the loss-in-weight scale 2 through a pipe. The limestone fine powder in the feeding bin 1 is fed into the preheater 4 through the inlet of the screw feeder 3 by controlling the feeding speed of the loss-in-weight scale 2. The preheater 4 is provided with an inlet and an exhaust port at the top. The inlet of the preheater 4 is connected to the discharge port of the screw feeder 3. The preheater 4 is provided with an air inlet on one side and a ore discharge port at the bottom. A powder dispersion device is provided at the ore discharge port to disperse the limestone fine powder so that the limestone fine powder is evenly dispersed into the suspension calcining furnace 5.

[0026] The calcination unit includes a suspension calcination furnace 5, a cyclone separator 6, and a burner 7. A feed port is located on one side of the suspension calcination furnace 5, connected to the discharge port at the bottom of the preheater 4. The preheated limestone powder is dispersed into the suspension calcination furnace 5 through the discharge port. Under the influence of high temperature and hot air, the limestone powder undergoes calcination in a spiral or vortex state within the suspension calcination furnace 5. The other side of the suspension calcination furnace 5 is connected to the upper part of the cyclone separator 6. After calcination, a portion of the calcined product, along with the hot air, enters the cyclone separator 6 through the flue gas passage connected to the upper part of the suspension calcination furnace 5. The lower part of the suspension calcining furnace 5 is equipped with an air inlet, which is connected to the burner 7. The fuel of the burner 7 is natural gas or liquefied petroleum gas. The hot gas generated by combustion enters the furnace through the air inlet at the bottom of the suspension calcining furnace 5 to maintain a stable calcination temperature inside the suspension calcining furnace 5. The bottom of the suspension calcining furnace 5 is equipped with a discharge port. The cyclone separator 6 is equipped with an exhaust port above it, which is connected to the air inlet on one side of the preheater 4 through a flue gas passage. The hot gas after separation enters the preheater 4 to provide heat for the preheater 4 and realize the recovery and utilization of waste heat. The cyclone separator 6 is also equipped with a discharge port below it.

[0027] The cooling unit includes a first cooler 8 and a first Roots blower 9. The first cooler 8 adopts a single-stage or multi-stage series structure, with an exhaust port and two feed ports at the top. The first feed port of the first cooler 8 is connected to the discharge port of the cyclone separator 6 through a pipe, and the calcined product separated in the cyclone separator 6 is added to the first cooler 8. The second feed port of the first cooler 8 is connected to the discharge port at the bottom of the suspension calcining furnace 5 through a discharge pipe, and another part of the calcined product that settles to the bottom of the suspension calcining furnace 5 is added to the first cooler 8 through a conveying device. An air inlet is provided on one side of the lower part of the first cooler 8, which is connected to the first Roots blower 9 through a pipe. The first Roots blower 9 sends cooling air into the first cooler 8 to cool the calcined product. After cooling, the calcined product is discharged through the discharge port at the bottom of the first cooler 8 and added to the product bin 10 through a conveying device.

[0028] The exhaust gas treatment unit includes a ceramic dust collector 11, a first ash trough 12, a second cooler 13, a second Roots blower 14, a bag filter 15, a second ash trough 16, a third cooler 17, a third Roots blower 18, an exhaust gas processor 19, and a chimney 20. The ceramic dust collector 11 has two air inlets on one side. The first air inlet of the ceramic dust collector 11 is connected to the exhaust port of the preheater 4 through a flue gas passage. The second air inlet of the ceramic dust collector 11 is connected to the exhaust port of the first cooler 8. The preheater 4 and the first cooler 8... The exhaust gas is discharged into the ceramic dust collector 11 through the exhaust port and pipeline. An exhaust port is located on the other side of the ceramic dust collector 11, connected to the air inlet at the top of the second cooler 13 via a flue gas passage. The dust-removed gas enters the second cooler 13 through the exhaust port. A discharge port is located at the bottom of the ceramic dust collector 11; after dust removal, the dust enters the first ash trough 12 through the discharge port and unloading device. An air inlet is located on one side of the second cooler 13, connected to a second Roots blower 14. Cooling air enters the second cooler 13 through the second Roots blower 14. 3. Heat exchange is carried out to achieve cooling; the lower part of the second cooler 13 is provided with an exhaust port, which is connected to the air inlet at the top of the bag filter 15. The cooled gas enters the bag filter 15 through the exhaust port; the bag filter 15 is provided with an exhaust port on one side, which is connected to the air inlet of the third cooler 17; the lower part of the bag filter 15 is provided with a discharge port, which is connected to the second ash trough 16 through a collection device. After the gas in the second cooler 13 is dusted, the dust is discharged into the second ash trough 16, and the gas enters the third cooler 17 through the exhaust port on one side. A third cooler 17 has an air inlet on one side, connected to a third Roots blower 18. The third Roots blower 18 delivers cooling air into the third cooler 17, reducing the gas temperature to below 80°C. An exhaust port is located at the bottom of the third cooler 17, connected to the air inlet of an exhaust gas processor 19 via a pipe, discharging the cooled gas into the exhaust gas processor 19. An exhaust outlet is located at the bottom of the exhaust gas processor 19, connected to a chimney 20 via a pipe, for collecting, compressing, and storing CO2 in the exhaust gas, and simultaneously treating NO in the exhaust gas. x After the treated exhaust gas meets the emission standards, it is discharged into the environment through chimney 20.

Claims

1. A pulverized limestone suspension calcining system having a waste gas treatment function, characterized by, The application relates to a lime production system, which comprises a feeding unit, a calcining unit, a cooling unit, a product bin and a tail gas treatment unit, wherein the feeding unit is connected with the feeding end of the calcining unit, the discharging end of the calcining unit is communicated with the feeding end of the cooling unit, the discharging end of the cooling unit is communicated with the product bin, the feeding end of the feeding unit is communicated with the discharging end of the calcining unit, the discharging end of the feeding unit is communicated with the feeding end of the tail gas treatment unit, and the discharging end of the cooling unit is communicated with the feeding end of the tail gas treatment unit. The tail gas treatment unit comprises a ceramic dust collector, a first ash tank, a second cooler, a second Roots blower, a bag dust collector, a second ash tank, a third cooler, a third Roots blower, a waste gas treatment device and a chimney; two air inlets are arranged on one side of the ceramic dust collector; the first air inlet of the ceramic dust collector is connected with the exhaust port of the preheater in the feeding unit; the second air inlet of the ceramic dust collector is connected with the exhaust port on the upper portion of the first cooler in the cooling unit; an exhaust port is arranged on the other side of the ceramic dust collector and is connected with the air inlet of the second cooler; a mineral discharging port is arranged at the bottom of the ceramic dust collector and is connected with the first ash tank; an air inlet is arranged on one side of the second cooler and is connected with the second Roots blower; an exhaust port is arranged below the second cooler and is connected with the air inlet on the upper portion of the bag dust collector; an exhaust port is arranged on one side of the bag dust collector and is connected with the air inlet of the third cooler; a material discharging port is arranged on the lower portion of the bag dust collector and is connected with the second ash tank; an air inlet is arranged on one side of the third cooler and is connected with the third Roots blower; an exhaust port is arranged below the third cooler and is connected with the air inlet of the waste gas treatment device; an exhaust port is arranged below the waste gas treatment device and is communicated with the chimney. The exhaust gas processor is used to collect, compress, store CO2 in the exhaust gas, and at the same time to treat NO in the exhaust gas x gas.

2. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 1, characterized by, The feeding unit further comprises a feeding bin, a loss-in-weight scale and a screw feeder; a discharging port is arranged at the lower end of the feeding bin and is connected with the feeding port of the loss-in-weight scale; the discharging port of the loss-in-weight scale is communicated with the feeding port of the screw feeder; a feeding port and an exhaust port are arranged on the upper portion of the preheater; the feeding port of the preheater is connected with the discharging port of the screw feeder; an air inlet is arranged on one side of the preheater; a mineral discharging port is arranged at the bottom of the preheater; and a powder dispersing device is arranged at the mineral discharging port.

3. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 2, characterized by, The calcining unit comprises a suspension calcining furnace, a cyclone separator and a combustion machine; a feeding port is arranged on one side of the suspension calcining furnace and is connected with the mineral discharging port at the bottom of the preheater; the other side of the suspension calcining furnace is communicated with the upper portion of the cyclone separator; an air inlet is arranged at the lower portion of the suspension calcining furnace and is connected with the combustion machine; a material discharging port is arranged at the bottom of the suspension calcining furnace; an exhaust port is arranged above the cyclone separator and is connected with the air inlet of the preheater; and a material discharging port is arranged below the cyclone separator.

4. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 3, characterized by, The cooling unit further comprises a first Roots blower; an exhaust port and two feeding ports are arranged on the upper portion of the first cooler; the first feeding port of the first cooler is connected with the material discharging port of the cyclone separator; the second feeding port of the first cooler is connected with the material discharging port at the bottom of the suspension calcining furnace; an air inlet is arranged on one side of the lower portion of the first cooler and is connected with the first Roots blower; and a discharging port is arranged at the bottom of the first cooler and is communicated with the product bin.

5. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 2, characterized by, The feeding bin is a feeding bin with a drying function, which is used for drying the limestone powder in the feeding bin.

6. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 2, characterized by, The powder dispersing device is used for dispersing the limestone powder.

7. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 3, characterized by, The fuel of the combustion machine is natural gas or liquefied gas.

8. The pulverized limestone suspension calcining system having a waste gas treatment function according to claim 4, characterized by, The first cooler adopts a single-stage structure or a multi-stage series structure. The first cooler adopts a single-stage structure or a multi-stage series structure.

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