A small-particle lime production system and process based on CO2 enrichment

Abstract

A small particle lime production system based on CO2 enrichment, the system includes a lime kiln. The lime kiln includes a preheating furnace chamber, a suspension calcination furnace chamber and a cooling furnace chamber. The suspension calcination furnace chamber is arranged on the central axis of the lime kiln, and the preheating furnace chamber and the cooling furnace chamber are arranged around the suspension calcination furnace chamber. The preheating furnace chamber is located in the upper part of the periphery of the suspension calcination furnace chamber, and the cooling furnace chamber is located in the lower part of the periphery of the suspension calcination furnace chamber. A preheating section discharge port communicating with the suspension calcination furnace chamber is arranged at the lower part of the preheating furnace chamber. A calcination section overflow port communicating with the cooling furnace chamber is arranged at the upper part of the suspension calcination furnace chamber. A flue gas inlet and a flue gas outlet are arranged on the suspension calcination furnace chamber. The present invention adopts an independent fluidized suspension calcination furnace chamber, which can effectively overcome the problems of poor air permeability of small particle limestone materials and inability to carry out shaft furnace calcination, and can realize the preparation of high-purity CO2 gas while producing small particle lime, avoiding carbon emissions and resource waste.

Description

Technical Field

[0001] The present invention relates to a lime production device and process, in particular to a small-particle lime production system and process based on CO2 enrichment, belonging to the technical field of lime production. Background Art

[0002] Lime is an important industrial raw material and is widely used in fields such as metallurgy and construction. Among the limestone raw materials mined from mines, more than 27% of the materials are fine particles with a particle size less than 10 mm. Due to poor air permeability, the materials of this size cannot meet the requirements for feeding into a shaft kiln or a rotary kiln and are generally directly discarded, resulting in relatively serious resource waste. Under this background, developing lime production technologies and equipment for low-energy calcination of small-particle lime and low CO2 emissions has become a hot and difficult point in the technical research in this field.

[0003] The double-shaft lime kiln is a widely used and technically advanced industrial lime production equipment at present. It adopts the process of double-shaft regenerative calcination and can obtain extremely high thermal efficiency. The heat required for the calcination process is provided by directly heating with fossil fuel combustion. The cooling medium for the cooling process is normal-temperature air, and the high-temperature flue gas generated in the calcination and cooling processes is used as the heat source in the preheating process. Such a process design can make full use of the waste heat of the flue gas and has a high fuel utilization efficiency. However, due to the mixing of the calcination flue gas and the cooling air, there are many impurity gases such as N2 in the tail gas, resulting in a low CO2 concentration in the discharged tail gas, generally only 20-30%. This makes the technology for enriching and capturing CO2 in the tail gas difficult and costly. As a result, at present, the enrichment and capture of CO2 in the lime kiln tail gas is almost zero, resulting in serious greenhouse gas emissions and resource waste. At the same time, since the particle size of the material directly affects the air permeability, the smaller the particle size, the lower the air permeability, and the more uneven the air flow distribution and heat distribution tend to be. Therefore, the double-shaft kiln has strict requirements for the particle size of the feeding material, generally requiring it to be greater than 30-40 mm, and it cannot calcine fine particles less than 10 mm, resulting in low utilization rate of the raw materials for the double-shaft kiln.

[0004] Figure 2It is a schematic structural diagram of the most widely used double-shaft lime kiln at the present stage. It mainly consists of two kiln shafts that are mirror images of each other, and a connecting channel with interconnected gases is arranged between the two kiln shafts. An embedded pulverized coal spray gun is arranged in the middle of the kiln shaft, a channel for introducing combustion-supporting air and discharging flue gas is arranged on the side, a cooling air duct is arranged at the bottom, a flue gas duct is arranged at the top, and a dust collector is connected to the end of the flue gas duct. During the production process, lime materials are fed into the combustion chamber from the top of the kiln shaft, combustion-supporting air (O2: 21%, N2: 79%) is fed into the combustion chamber from the side, pulverized coal is fed into the combustion chamber from the pulverized coal spray gun by conveying air (O2: 21%, N2: 79%), the pulverized coal burns in the combustion chamber to generate high-temperature flue gas, heating the lime materials, causing the lime materials to rapidly heat up and decompose to produce CaO and CO2. The generated high-temperature CaO moves downward, is cooled by cooling air (O2: 21%, N2: 79%) to below 100 °C and then discharged from the bottom of the furnace to form finished CaO. The high-temperature air generated by cooling the high-temperature CaO and the high-temperature flue gas generated by calcination enter the regenerative chamber through the connecting channel, exchange heat with the cold materials in the regenerative chamber, and then are discharged from the flue gas outlet at the top after the temperature drops to about 120 °C, and are discharged into the surrounding environment after being dust-removed and purified by the dust collector at the end of the flue gas duct. The two kiln shafts periodically exchange roles to complete the continuous calcination of lime.

[0005] Under the above structure, the heat energy of the flue gas is fully utilized, and the energy utilization efficiency is very high. At the same time, due to the relatively simple equipment, it is widely used in the production of lime. However, the above structure has several obvious defects:

[0006] 1. The CO2 concentration in the tail gas is low, and the enrichment and capture are difficult and costly;

[0007] Under the existing equipment structure, a large amount of impurity gases such as O2 and N2 will be introduced into the system during the combustion-supporting, cooling, and pulverized coal conveying processes (relative to the by-product CO2), resulting in a very low CO2 content in the discharged flue gas, generally only 20-30%. The cost of CO2 enrichment and capture is negatively correlated with the initial CO2 concentration in the flue gas. The lower the CO2 concentration, the higher the enrichment and capture cost. The too low CO2 concentration in the lime production tail gas under the existing equipment leads to a high enrichment and capture cost, which has become the main obstacle restricting the recycling of CO2 in the lime production process.

[0008] 2. It has high requirements for the air permeability of the materials and cannot handle small-particle materials, resulting in low raw material utilization rate;

[0009] Under the existing equipment structure, since the preheating, calcination, and cooling processes are carried out in series in the same vertical furnace, the height of the material layer is high, and the requirement for the air permeability of the material is high. The particle size of the material has a very large impact on the air permeability of the bed. As the particle size of the material decreases, the air permeability of the bed drops sharply. Therefore, the existing equipment structure can only process lime materials larger than 30 - 40 mm and cannot process small particle lime less than 10 mm, resulting in a low utilization rate of raw materials. Summary of the Invention

[0010] Aiming at the problems of large CO2 emissions, high enrichment and capture costs, and resource waste in the existing lime production equipment, and at the same time, the low utilization rate of raw materials caused by the inability to process small particle limestone, the present invention proposes a small particle lime production system and process based on CO2 enrichment. In the solution of the present invention, the suspension calcination furnace of the lime kiln is arranged on the central axis, and the preheating furnace and the cooling furnace are arranged around the suspension calcination furnace. The preheating furnace is located in the upper outer part of the suspension calcination furnace, and the cooling furnace is located in the lower outer part of the suspension calcination furnace; a preheating section discharge port communicating with the suspension calcination furnace is provided at the lower part of the preheating furnace, a calcination section overflow port communicating with the cooling furnace is provided at the upper part of the suspension calcination furnace, and a separate flue gas inlet and a flue gas outlet are also provided on the suspension calcination furnace. Based on this structural setting, the present invention adopts an independent fluidized suspension calcination furnace, which can effectively overcome the problems of poor air permeability of small particle limestone materials and inability to carry out shaft furnace calcination. At the same time, this equipment structure adopts a form of air flow organization in which the cooling - preheating air flow is separated from the calcination air flow, which can realize the preparation of high - purity CO2 gas and effectively recover the CO2 gas in the lime production process, thereby avoiding carbon emissions and resource waste in the lime production process.

[0011] According to the first embodiment of the present invention, a small particle lime production system based on CO2 enrichment is provided.

[0012] A small particle lime production system based on CO2 enrichment, the system includes a lime kiln. The lime kiln includes a preheating furnace, a suspension calcination furnace, and a cooling furnace. The suspension calcination furnace is arranged on the central axis of the lime kiln, and the preheating furnace and the cooling furnace are arranged around the suspension calcination furnace. Among them, the preheating furnace is located in the upper outer part of the suspension calcination furnace, and the cooling furnace is located in the lower outer part of the suspension calcination furnace. A preheating section discharge port communicating with the suspension calcination furnace is provided at the lower part of the preheating furnace. A calcination section overflow port communicating with the cooling furnace is provided at the upper part of the suspension calcination furnace. An inlet for materials and an exhaust port for waste gas are provided on the preheating furnace, a discharge port and an inlet for cooling air are provided on the cooling furnace. A flue gas inlet and a flue gas outlet are provided on the suspension calcination furnace, and the flue gas outlet is connected to a flue gas discharge pipe.

[0013] Preferably, the system further includes a preheating section grid. The preheating section grid is arranged at the bottom of the preheating furnace and above the cooling furnace.

[0014] In the present invention, the flue gas inlet is located at the bottom of the suspension calcination furnace, the flue gas outlet is located at the upper part of the suspension calcination furnace, and the flue gas discharge pipe passes through the preheating furnace. The flue gas outlet of the suspension calcination furnace is connected to the circulation pipeline through the flue gas discharge pipe, and the circulation pipeline is connected to the flue gas inlet of the suspension calcination furnace.

[0015] Preferably, a recovery pipeline is branched off from the circulation pipeline, and the recovery pipeline is connected to the CO2 recovery device.

[0016] In the present invention, the system further includes a calcination section air box provided at the flue gas inlet of the suspension calcination furnace. Preferably, a heat replenisher is provided in the calcination section air box. More preferably, the heat replenisher is one of an electric heat replenisher, a microwave heat replenisher, and an oxygen-enriched hot air heat replenisher.

[0017] Preferably, the system further includes a pallet machine provided at the discharge port of the preheating section. Preferably, a passage for the gas flow to pass through is provided on the pallet machine.

[0018] In the present invention, a plurality of discharge ports of the preheating section are provided at the lower part of the preheating furnace. The plurality of discharge ports of the preheating section are evenly distributed around the outer periphery of the suspension calcination furnace. A pallet machine is equipped at each discharge port of the preheating section.

[0019] In the present invention, a plurality of overflow ports of the calcination section are provided at the upper part of the suspension calcination furnace. The plurality of overflow ports of the calcination section are evenly distributed around the outer periphery of the suspension calcination furnace.

[0020] Preferably, a diverter is provided at the position where the recovery pipeline is branched off from the circulation pipeline. A finished product fan is provided on the recovery pipeline between the diverter and the CO2 recovery device. A circulation fan is provided on the circulation pipeline between the diverter and the flue gas inlet of the suspension calcination furnace.

[0021] Preferably, the system further includes a finished product small particle lime device. The discharge port of the cooling furnace is connected to the finished product small particle lime device.

[0022] According to the second embodiment of the present invention, a small particle lime production process based on CO2 enrichment is provided.

[0023] A small particle lime production process based on CO2 enrichment or a small particle lime production process using the system described in the first embodiment, the process includes the following steps:

[0024] 1) Small particle limestone materials enter the preheating furnace of the lime kiln and move downward under the action of gravity. During the movement, the materials complete the preheating of the preheating furnace. The preheated materials enter the suspension calcination furnace through the discharge port of the preheating section under the action of the pallet machine. The materials are in a fluidized state under the action of the air flow supplied to the suspension calcination furnace, and complete the calcination decomposition as the temperature rises, generating small particle lime and CO2 gas.

[0025] 2) The small particle lime generated by decomposition moves upward under the buoyancy of the air flow, and finally flows out of the suspension calcination furnace from the overflow port of the calcination section and enters the cooling furnace for cooling. After the cooling is completed, the finished small particle lime is obtained.

[0026] 3) The CO2 gas generated by decomposition enters the circulation pipeline through the flue gas discharge pipeline. After passing through the shunt on the circulation pipeline, the CO2 gas is divided into two parts. One part is transported to the CO2 recovery device, and the other part enters the air box of the calcination section. The heater installed in the air box of the calcination section heats this part of the CO2 gas and then sends it into the suspension calcination furnace to continue participating in the calcination decomposition of the small particle limestone materials.

[0027] 4) The cooling air is sent into the cooling furnace from the cooling air inlet of the cooling furnace. The cooling air passes through the high-temperature small particle lime entering the cooling furnace from bottom to top. After completing the heat exchange with the high-temperature small particle lime, the temperature of the cooling air rises to form high-temperature hot air, which continues to pass through the grille of the preheating section and then enters the preheating furnace to preheat the materials. The waste gas obtained after the preheating is completed is discharged from the waste gas outlet of the preheating furnace.

[0028] In the present invention, in step 1), the particle size of the small particle limestone materials < 10 mm.

[0029] In the present invention, in step 1), the temperature of the preheated small particle limestone materials is 600 - 800 °C, preferably 650 - 750 °C. The temperature for realizing the calcination decomposition in the suspension calcination furnace is 800 - 1050 °C, preferably 900 - 1000 °C.

[0030] In step 2), the temperature of the finished small particle lime obtained after the cooling is completed is 80 - 100 °C.

[0031] In the present invention, in step 4), the cooling air is normal temperature air. The temperature of the normal temperature air is generally 15 - 25 °C, such as 20 °C or 25 °C.

[0032] In the present invention, in step 3), the temperature of the CO2 gas sent into the suspension calcination furnace after being heated by the heater is 1000 - 1100 °C.

[0033] In step 4), the temperature of the high-temperature hot air formed after heat exchange with the small particles of high-temperature lime is 650-850°C, preferably 700-800°C. The temperature of the waste gas discharged from the waste gas outlet of the preheating furnace after preheating is 100-130°C.

[0034] According to statistics, among the limestone raw materials mined from the mine, more than 27% of the materials are fine particles with a particle size less than 10 mm. Due to poor air permeability, the materials of this size cannot meet the requirements for feeding into the existing shaft kiln or rotary kiln and are often directly discarded, resulting in serious waste of resources. In addition, in the existing lime production process, it is difficult to capture and utilize the tail gas due to the low CO2 concentration, resulting in serious greenhouse gas emissions and waste of resources. To address these technical problems, the present invention proposes a small-particle lime production system and process based on CO2 enrichment. In the solution of the present invention, the suspension calcination furnace of the lime kiln is arranged on the central axis, and the preheating furnace and the cooling furnace are arranged around the suspension calcination furnace. The preheating furnace is located in the upper outer part of the suspension calcination furnace, and the cooling furnace is located in the lower outer part of the suspension calcination furnace; a preheating section discharge port communicating with the suspension calcination furnace is provided at the lower part of the preheating furnace, a calcination section overflow port communicating with the cooling furnace is provided at the upper part of the suspension calcination furnace, and a separate flue gas inlet and a flue gas outlet are also provided on the suspension calcination furnace. Based on this structural arrangement, the present invention adopts an independent fluidized suspension calcination furnace, which can effectively overcome the problems of poor air permeability of small-particle limestone materials and inability to be shaft-calcined. At the same time, the air flow organization form of separating the cooling-preheating air flow from the calcination air flow is adopted in the equipment structure, which can realize the preparation of high-purity CO2 gas and effectively recover the CO2 gas in the lime production process, thus avoiding carbon emissions and resource waste in the lime production process.

[0035] In the present invention, the small-particle lime production system based on CO2 enrichment includes a lime kiln, and the lime kiln further includes a preheating furnace chamber, a suspension calcination furnace chamber, and a cooling furnace chamber. Different from the existing lime production equipment where the preheating, calcination, and cooling processes are carried out in series in the same vertical furnace chamber, in this application, the suspension calcination furnace chamber is arranged on the central axis of the lime kiln, and the preheating furnace chamber and the cooling furnace chamber are arranged around the suspension calcination furnace chamber. The preheating furnace chamber is located in the upper outer periphery of the suspension calcination furnace chamber, and the cooling furnace chamber is located in the lower outer periphery of the suspension calcination furnace chamber, that is, the suspension calcination furnace chamber and the preheating furnace chamber (or the cooling furnace chamber) are not in the same vertical furnace chamber. Such an arrangement can reduce the height of the material layer and improve the air permeability of the material, so that small-particle materials with a size of <10 mm can meet the requirements for entering the kiln. A preheating section discharge port communicating with the suspension calcination furnace chamber is provided at the lower part of the preheating furnace chamber, and a calcination section overflow port communicating with the cooling furnace chamber is provided at the upper part of the suspension calcination furnace chamber. An inlet and an exhaust gas outlet are provided on the preheating furnace chamber, generally located at the top or upper part of the preheating furnace chamber. A discharge port and a cooling air inlet are provided on the cooling furnace chamber, generally located at the bottom or lower part of the cooling furnace chamber. A flue gas inlet and a flue gas outlet are also separately provided on the suspension calcination furnace chamber to provide air flow for the suspension calcination furnace chamber as an independent fluidized calcination furnace chamber. The small-particle limestone material is in a suspended boiling state in the suspension calcination furnace chamber, greatly improving the heat transfer intensity between the small-particle limestone material and the heat exchange medium, and further overcoming the problems of poor air permeability of the small-particle limestone material and inability to be calcined in a shaft furnace; at the same time, this structural arrangement separates the calcination gas flow (high-purity CO2) from the cooling-preheating gas flow, avoiding the dilution of the high-concentration CO2 gas in the suspension calcination furnace chamber by the cooling air, that is, while producing lime, a high-purity CO2 gas by-product is obtained.

[0036] As a preferred solution, the lime kiln in the present invention further includes a preheating section grid arranged at the bottom of the preheating furnace chamber and above the cooling furnace chamber. The preheating section grid separates the preheating furnace chamber from the downstream cooling furnace chamber. The preheating section grid allows the gas flow to pass through but blocks the material from passing through. That is, the high-temperature flue gas discharged from the cooling furnace chamber can enter the preheating furnace chamber through the preheating section grid to preheat the material, but the material in the preheating furnace chamber will not pass through the preheating section grid and enter the cooling furnace chamber.

[0037] In the present invention, the heat required for calcining and decomposing materials in the suspension calcination furnace is mainly supplied by the self-circulation of high-temperature flue gas generated in the calcination process, thereby avoiding the introduction of impurity components such as O2 and N2 during the calcination heat supply process, and further improving the purity of CO2 gas in the suspension calcination furnace. A calcination section air box is provided at the bottom of the suspension calcination furnace of the present invention, and a heater (such as an electric heater, a microwave heater, or an oxygen-enriched hot air heater) is provided in the calcination section air box. Considering that the heat self-circulation of the high-temperature flue gas generated during the calcination process may not be sufficient to meet the heat required for the next round of calcination of small particle limestone materials, the calcined high-temperature flue gas discharged from the flue gas outlet of the suspension calcination furnace is first heated and raised in temperature by the heater in the calcination section air box, and then evenly sent into the suspension calcination furnace to supply heat for the calcination and decomposition of the materials in the suspension calcination furnace. At the same time, this part of the self-circulating flue gas also provides air flow for the fluidization of the materials in the suspension calcination furnace. By controlling parameters such as the flow rate and flow of the air flow sent from the calcination section air box into the suspension calcination furnace, the fluidization of the corresponding particle size materials can be satisfied, making the materials in a suspended boiling state.

[0038] In the present invention, a preheating section discharge port communicating with the suspension calcination furnace is provided at the lower part of the preheating furnace, and a pallet machine is arranged at the preheating section discharge port. Through the movement of the pallet machine, the preheated materials can enter the suspension calcination furnace from the preheating section discharge port. Preferably, a channel for the air flow to pass through is also provided on the pallet machine, that is, the arrangement of the pallet machine can realize the smooth inflow of materials from the preheating furnace to the suspension calcination furnace while not affecting the entry of the cooling flue gas into the preheating furnace. A calcination section overflow port communicating with the cooling furnace is provided at the upper part of the suspension calcination furnace for transferring the calcined lime from the suspension calcination furnace to the cooling furnace. During the lime production process, small particle limestone materials pass through the preheating furnace, the suspension calcination furnace, and the cooling furnace in sequence to complete the preheating-calcination-cooling process, forming finished small particle calcium oxide. The high-temperature hot air generated by heat exchange in the cooling furnace directly enters the preheating furnace without passing through the suspension calcination furnace, avoiding dilution of the high-concentration CO2 gas in the suspension calcination furnace. In this application, since the materials in the suspension calcination furnace are in a fluidized state, that is, the pressure in the suspension calcination furnace is greater than that in the cooling furnace, the high-temperature hot air formed after the cooling air entering the cooling furnace exchanges heat with the high-temperature calcium oxide will not flow back into the suspension calcination furnace from the calcination section overflow port, but directly enters the preheating furnace upward through the preheating section grid, thereby avoiding dilution of the high-concentration CO2 gas in the suspension calcination furnace, and further realizing the preparation and subsequent resource utilization of high-purity CO2 gas, and avoiding carbon emissions and resource waste in the lime production process.

[0039] In this application, several preheating section discharge openings communicating with the suspension calcination furnace are arranged at the lower part of the inner wall of the preheating furnace, and the plurality of preheating section discharge openings are evenly distributed around the outer periphery of the suspension calcination furnace. A pallet machine is equipped at each preheating section discharge opening. Correspondingly, a plurality of calcination section overflow openings can also be arranged at the upper part of the suspension calcination furnace in this application. The plurality of calcination section overflow openings are evenly distributed around the outer periphery of the suspension calcination furnace. In this application, the number of calcination section overflow openings can be one or more. The plurality of calcination section overflow openings can be arranged circumferentially evenly or unilaterally. When a plurality of calcination section overflow openings are arranged circumferentially evenly, the materials in the cooling chamber will be more evenly distributed at this time.

[0040] In this application, the flue gas outlet of the suspension calcination furnace is connected to a flue gas discharge pipe, and the flue gas discharge pipe passes through the preheating furnace and is connected to the heat recovery pipeline. A shunt is added to the heat recovery pipeline for discharging the calcination flue gas in this solution to shunt the high-temperature flue gas generated by calcination and decomposition in the suspension calcination furnace. Part of it is used as a heat carrier to circulate and supply heat in the calcination chamber, and the remaining flue gas (basically equal to the amount of CO2 released by the decomposition of limestone) forms a high-purity CO2 product. At the same time, the high-temperature flue gas generated during the cooling process does not pass through the suspension calcination furnace and directly enters the preheating furnace to preheat the materials. Based on this, the small particle lime production system provided in this application separates the two airflows of the cooling-preheating process and the pure CO2 gas generated during the calcination process, avoiding the dilution of the CO2 concentration in the calcination flue gas by impurity components such as O2 and N2 in the cooling air; at the same time, the cooling flue gas is used to preheat the materials, and the calcination flue gas is used for calcination heat supply and recycling. This not only ensures the efficient utilization of the flue gas waste heat but also further avoids the introduction of impurity components such as O2 and N2 during the calcination process. Therefore, by using the device of this application, high-purity CO2 gas can be obtained while producing lime, avoiding carbon emissions and resource waste in the existing lime production process. Moreover, the lime production system in this application uses an independent fluidized calcination furnace, and the small particle limestone materials are in a suspended boiling state in the suspension calcination furnace, greatly increasing the heat transfer intensity between the small particle limestone materials and the heat exchange medium, and effectively overcoming the problems of poor air permeability and uneven calcination of small particle materials.

[0041] Using the small particle lime production system based on CO2 enrichment described in the present invention for lime production, during the production process, small particle (<10 mm) limestone material (main component CaCO3) is fed into the preheating furnace through the feed inlet on the preheating furnace hearth. The material moves downward under the action of gravity and is gradually heated to a preheating temperature of about 700 °C by the high-temperature flue gas fed from the bottom of the preheating furnace hearth. Then, under the action of the pallet machine, it enters the suspension calcination furnace through the discharge port of the preheating section. The high-temperature flue gas fed from the bottom of the suspension calcination furnace lifts the material in the suspension calcination furnace, making it in a fluidized state in the suspension calcination furnace. The small particle limestone material just entering the suspension calcination furnace has a large density (about 2700 - 3000 kg / m 3 ), and gradually descends to the bottom of the suspension calcination furnace. During the descent, the temperature gradually rises to the calcination temperature (about 1050 °C) and decomposition occurs. The density of the small particle CaO generated by decomposition is greatly reduced (about 1600 kg / m 3 ). Under the action of buoyancy, the undecomposed CaCO3 material with a large density moves downward, and the decomposed CaO material with a small density moves upward. Heat exchange occurs between the hot and cold materials and between the hot flue gas and the cold materials. Finally, the decomposed CaO flows out of the suspension calcination furnace through the overflow port of the calcination section and enters the cooling furnace, while the generated pure high-temperature CO2 gas enters the regenerative pipeline from the flue gas outlet of the suspension calcination furnace. The CO2 gas in the regenerative pipeline is divided into two parts by the diverter. One part is pumped into the CO2 recovery device by the finished product fan, and the other part is pumped into the calcination section air box at the bottom of the suspension calcination furnace by the circulation fan. The heater (electric heat supplement or microwave heat supplement or oxy-fuel hot blast stove heat supplement) arranged in the air box further heats the recycled CO2 gas to about 1100 °C and then sends it into the suspension calcination furnace. Cooling air (generally normal temperature air) is fed from the bottom of the cooling furnace. After the high-temperature CaO is cooled to about 100 °C, it is discharged from the bottom of the cooling furnace. After completing heat exchange with the high-temperature material, the temperature of the cooling air rises from normal temperature to about 800 °C, and then enters the preheating furnace through the preheating section grille and the air flow channel on the pallet machine, contacts and exchanges heat with the cold material in the preheating furnace. After the waste gas temperature gradually drops to about 120 °C, it is discharged from the waste gas outlet at the top of the preheating furnace.

[0042] In this application, the waste gas discharged from the waste gas outlet after preheating the material can be transported to the waste heat utilization device for further utilization of the waste heat. The high-temperature CO2 gas discharged from the suspension calcination furnace and split can also be transported to the CO2 recovery device after waste heat utilization to complete the collection and resource utilization of CO2.

[0043] Compared with the prior art, the present invention has the following beneficial technical effects:

[0044] 1. The present invention adopts an independent fluidized calcination furnace chamber, and the suspension calcination furnace chamber and the preheating furnace chamber (or cooling furnace chamber) are not in the same vertical furnace chamber, thereby reducing the height of the material layer and improving the air permeability of the material. Moreover, the small particle limestone material is in a suspended boiling state in the suspension calcination furnace chamber, greatly increasing the heat transfer intensity between the small particle limestone material and the heat exchange medium, and further overcoming the problems of poor air permeability of small particle materials and inability to be calcined in a shaft furnace, avoiding the waste of resources of small particle limestone raw materials.

[0045] 2. The present invention arranges the suspension calcination furnace chamber on the central axis, and the preheating furnace chamber and the cooling furnace chamber are arranged around the suspension calcination furnace chamber. The preheating furnace chamber is located in the upper outer periphery of the suspension calcination furnace chamber, and the cooling furnace chamber is located in the lower outer periphery of the suspension calcination furnace chamber. The suspension calcination furnace chamber is also provided with a separate flue gas inlet and a flue gas outlet. Through such a structural arrangement, the two airflows of the cooling-preheating air flow and the CO2 gas generated during the calcination process are separated from each other, avoiding the dilution of CO2 by impurity components such as O2 and N2 in the cooling air. Thus, while producing lime, high-purity CO2 gas is obtained, realizing the collection and resource utilization of CO2 gas.

[0046] 3. The present invention shunts the calcination flue gas, and a part of it is used as a heat carrier to circulate and supply heat in the calcination chamber. The self-circulation of the calcination flue gas provides heat for the calcination and decomposition of the materials in the calcination chamber, that is, while ensuring the utilization rate of the flue gas waste heat, it avoids introducing impurity components such as O2 and N2 during the calcination heat supply process, further improving the purity of the CO2 gas in the calcination chamber. Correspondingly, the remaining part of the calcination flue gas forms a high-purity CO2 product, thus avoiding carbon emissions and resource waste during the lime production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic structural diagram of a small particle lime production system based on CO2 enrichment according to the present invention;

[0048] Figure 2 is a schematic structural diagram of lime production equipment in the prior art.

[0049] Reference Numerals:

[0050] 1: Lime kiln; 101: Preheating furnace chamber; 10101: Discharge opening of the preheating section; 102: Suspension calcination furnace chamber; 10201: Overflow opening of the calcination section; 103: Cooling furnace chamber; 2: Grating of the preheating section; 3: CO2 recovery device; 4: Air box of the calcination section; 5: Heat supplementer; 6: Pallet machine; 7: Shunt device; 8: Finished product fan; 9: Circulation fan; 10: Finished product small particle lime device;

[0051] L: Flue gas discharge pipeline; S1: Circulation pipeline; S2: Recovery pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] The technical solutions of the present invention will be illustrated by way of examples below. The scope of protection claimed by the present invention includes but is not limited to the following embodiments.

[0053] According to the first embodiment of the present invention, a small-particle lime production system based on CO2 enrichment is provided.

[0054] A small-particle lime production system based on CO2 enrichment, the system includes a lime kiln 1. The lime kiln 1 includes a preheating furnace chamber 101, a suspension calcination furnace chamber 102, and a cooling furnace chamber 103. The suspension calcination furnace chamber 102 is arranged on the central axis of the lime kiln 1, and the preheating furnace chamber 101 and the cooling furnace chamber 103 are arranged around the suspension calcination furnace chamber 102. Among them, the preheating furnace chamber 101 is located in the upper part of the periphery of the suspension calcination furnace chamber 102, and the cooling furnace chamber 103 is located in the lower part of the periphery of the suspension calcination furnace chamber 102. A preheating section discharge port 10101 communicating with the suspension calcination furnace chamber 102 is provided at the lower part of the preheating furnace chamber 101. A calcination section overflow port 10201 communicating with the cooling furnace chamber 103 is provided at the upper part of the suspension calcination furnace chamber 102. The preheating furnace chamber 101 is provided with a feed inlet and an exhaust gas outlet, and the cooling furnace chamber 103 is provided with a discharge port and a cooling air inlet. The suspension calcination furnace chamber 102 is provided with a flue gas inlet and a flue gas outlet, and the flue gas outlet is connected with a flue gas discharge pipeline L.

[0055] Preferably, the system further includes a preheating section grid 2. The preheating section grid 2 is arranged at the bottom of the preheating furnace chamber 101 and is located above the cooling furnace chamber 103.

[0056] In the present invention, the flue gas inlet is located at the bottom of the suspension calcination furnace chamber 102, the flue gas outlet is located at the upper part of the suspension calcination furnace chamber 102, and the flue gas discharge pipeline L passes through the preheating furnace chamber 101. The flue gas outlet of the suspension calcination furnace chamber 102 is connected to a circulation pipeline S1 through the flue gas discharge pipeline L, and the circulation pipeline S1 is connected to the flue gas inlet of the suspension calcination furnace chamber 102.

[0057] Preferably, a recovery pipeline S2 is branched from the circulation pipeline S1, and the recovery pipeline S2 is connected to a CO2 recovery device 3.

[0058] In the present invention, the system further includes a calcination section air box 4 arranged at the flue gas inlet of the suspension calcination furnace chamber 102. Preferably, a heater 5 is arranged in the calcination section air box 4. Further preferably, the heater 5 is one of an electric heater, a microwave heater, and an oxygen-enriched hot air heater.

[0059] Preferably, the system further includes a pallet machine 6 arranged at the preheating section discharge port 10101. Preferably, the pallet machine 6 is provided with a passage for air flow to pass through.

[0060] In the present invention, a plurality of preheating section discharge openings 10101 are provided at the lower part of the preheating furnace chamber 101. The plurality of preheating section discharge openings 10101 are evenly distributed around the outer periphery of the suspension calcination furnace chamber 102. A pallet machine 6 is equipped at each preheating section discharge opening 10101.

[0061] In the present invention, a plurality of calcination section overflow openings 10201 are provided at the upper part of the suspension calcination furnace chamber 102. The plurality of calcination section overflow openings 10201 are evenly distributed around the outer periphery of the suspension calcination furnace chamber 102.

[0062] Preferably, a diverter 7 is provided at the position where the recovery pipeline S2 branches off from the circulation pipeline S1. A finished product fan 8 is provided on the recovery pipeline S2 between the diverter 7 and the CO2 recovery device 3. A circulation fan 9 is provided on the circulation pipeline S1 between the diverter 7 and the flue gas inlet of the suspension calcination furnace chamber 102.

[0063] Preferably, the system further includes a finished product small particle lime device 10. The discharge port of the cooling furnace chamber 103 is connected to the finished product small particle lime device 10.

[0064] Example 1

[0065] As Figure 1 shown, a small particle lime production system based on CO2 enrichment, the system includes a lime kiln 1. The lime kiln 1 includes a preheating furnace chamber 101, a suspension calcination furnace chamber 102, and a cooling furnace chamber 103. The suspension calcination furnace chamber 102 is arranged on the central axis of the lime kiln 1, and the preheating furnace chamber 101 and the cooling furnace chamber 103 are arranged around the suspension calcination furnace chamber 102. Among them, the preheating furnace chamber 101 is located at the upper outer periphery of the suspension calcination furnace chamber 102, and the cooling furnace chamber 103 is located at the lower outer periphery of the suspension calcination furnace chamber 102. A preheating section discharge opening 10101 communicating with the suspension calcination furnace chamber 102 is provided at the lower part of the preheating furnace chamber 101. A calcination section overflow opening 10201 communicating with the cooling furnace chamber 103 is provided at the upper part of the suspension calcination furnace chamber 102. An inlet and an exhaust gas outlet are provided on the preheating furnace chamber 101, and a discharge port and a cooling air inlet are provided on the cooling furnace chamber 103. A flue gas inlet and a flue gas outlet are provided on the suspension calcination furnace chamber 102, and the flue gas outlet is connected with a flue gas discharge pipeline L.

[0066] Example 2

[0067] Repeat Example 1, except that the system further includes a preheating section grid 2. The preheating section grid 2 is arranged at the bottom of the preheating furnace chamber 101 and above the cooling furnace chamber 103.

[0068] Example 3

[0069] Repeat Example 2, except that the flue gas inlet is located at the bottom of the suspension calcination furnace chamber 102, the flue gas outlet is located at the upper part of the suspension calcination furnace chamber 102, and the flue gas discharge pipe L passes through the preheating furnace chamber 101. The flue gas outlet of the suspension calcination furnace chamber 102 is connected to the circulation pipeline S1 through the flue gas discharge pipe L, and the circulation pipeline S1 is connected to the flue gas inlet of the suspension calcination furnace chamber 102.

[0070] Example 4

[0071] Repeat Example 3, except that a recovery pipeline S2 is branched off from the circulation pipeline S1, and the recovery pipeline S2 is connected to the CO2 recovery device 3.

[0072] Example 5

[0073] Repeat Example 4, except that the system further includes a calcination section air box 4 provided at the flue gas inlet of the suspension calcination furnace chamber 102.

[0074] Example 6

[0075] Repeat Example 5, except that a heater 5 is provided in the calcination section air box 4. The heater 5 is an electric heater.

[0076] Example 7

[0077] Repeat Example 5, except that a heater 5 is provided in the calcination section air box 4. The heater 5 is a microwave heater.

[0078] Example 8

[0079] Repeat Example 5, except that a heater 5 is provided in the calcination section air box 4. The heater 5 is an oxygen-enriched hot air heater.

[0080] Example 9

[0081] Repeat Example 6, except that the system further includes a pallet machine 6 provided at the preheating section discharge opening 10101.

[0082] Example 10

[0083] Repeat Example 9, except that the pallet machine 6 is provided with a passage for the air flow to pass through.

[0084] Example 11

[0085] Repeat Example 10, except that a plurality of preheating section discharge openings 10101 are provided at the lower part of the preheating furnace chamber 101. The plurality of preheating section discharge openings 10101 are evenly distributed around the outer periphery of the suspension calcination furnace chamber 102. A pallet machine 6 is equipped at each preheating section discharge opening 10101.

[0086] Example 12

[0087] Repeat Example 11, except that a plurality of calcination section overflow ports 10201 are provided in the upper part of the suspension calcination furnace chamber 102. The plurality of calcination section overflow ports 10201 are evenly distributed around the outer periphery of the suspension calcination furnace chamber 102.

[0088] Example 13

[0089] Repeat Example 12, except that a diverter 7 is provided at the position where the recovery pipeline S2 branches off from the circulation pipeline S1. A finished product fan 8 is provided on the recovery pipeline S2 between the diverter 7 and the CO2 recovery device 3. A circulation fan 9 is provided on the circulation pipeline S1 between the diverter 7 and the flue gas inlet of the suspension calcination furnace chamber 102.

[0090] Example 14

[0091] Repeat Example 13, except that the system further includes a finished product small particle lime device 10. The discharge port of the cooling furnace chamber 103 is connected to the finished product small particle lime device 10.

[0092] Example 15

[0093] A small particle lime production process based on CO2 enrichment, the process comprising the following steps:

[0094] 1) Small particle limestone material enters the preheating furnace chamber 101 of the lime kiln furnace 1 and moves downward under the action of gravity. The material completes the preheating of the preheating furnace chamber 101 during the movement. The preheated material enters the suspension calcination furnace chamber 102 via the preheating section discharge port 10101 under the action of the pallet machine 6. The material is in a fluidized state under the action of the air flow supplied to the suspension calcination furnace chamber 102, and completes the calcination decomposition as the temperature rises, generating small particle lime and CO2 gas.

[0095] 2) The small particle lime generated by the decomposition moves upward under the buoyancy of the air flow, and finally flows out of the suspension calcination furnace chamber 102 from the calcination section overflow port 10201 and enters the cooling furnace chamber 103 for cooling. After the cooling is completed, the finished small particle lime is obtained.

[0096] 3) The CO2 gas generated by the decomposition enters the circulation pipeline S1 via the flue gas discharge pipeline L. After passing through the diverter 7 on the circulation pipeline S1, the CO2 gas is divided into two parts. One part is transported to the CO2 recovery device 3, and the other part enters the calcination section air box 4. The heater 5 provided in the calcination section air box 4 heats this part of the CO2 gas and then sends it into the suspension calcination furnace chamber 102 to continue to participate in the calcination decomposition of the small particle limestone material.

[0097] 4) Cooling air is fed into the cooling furnace 103 through the cooling air inlet. The cooling air passes through the high-temperature small-particle lime entering the cooling furnace 103 from bottom to top. After completing the heat exchange with the high-temperature small-particle lime, the temperature of the cooling air rises to form high-temperature hot air, which continues to pass upward through the preheating section grid 2 and then enters the preheating furnace 101 to preheat the material. After the preheating is completed, the exhaust gas obtained is discharged from the exhaust gas outlet of the preheating furnace 101.

[0098] Example 16

[0099] A small-particle lime production process based on CO2 enrichment uses the lime production system described in Example 14. This process includes the following steps:

[0100] 1) Small-particle limestone materials with a particle size < 10 mm enter the preheating furnace 101 of the lime kiln furnace 1 and move downward under the action of gravity. The materials complete the preheating of the preheating furnace 101 during the movement. The materials heated to about 710 °C after preheating enter the suspension calcination furnace 102 through the preheating section discharge port 10101 under the action of the pallet machine 6. The materials are in a fluidized state under the action of the air flow supplied to the suspension calcination furnace 102 and complete the calcination decomposition as the temperature rises to about 1048 °C, generating small-particle lime and CO2 gas.

[0101] 2) The small-particle lime generated by decomposition moves upward under the buoyancy of the air flow and finally flows out of the suspension calcination furnace 102 from the calcination section overflow port 10201 and enters the cooling furnace 103 for cooling. After the cooling is completed, the temperature drops to about 95 °C to obtain the finished small-particle lime.

[0102] 3) The CO2 gas generated by decomposition enters the circulation pipeline S1 through the flue gas discharge pipeline L. The CO2 gas is split into two parts after passing through the shunt 7 on the circulation pipeline S1. One part is transported to the CO2 recovery device 3, and the other part enters the calcination section air box 4. The heater 5 arranged in the calcination section air box 4 heats this part of the CO2 gas to about 1097 °C and then sends it into the suspension calcination furnace 102 to continue participating in the calcination decomposition of the small-particle limestone materials.

[0103] 4) Normal-temperature air used as cooling air is fed into the cooling furnace 103 through the cooling air inlet. The cooling air passes through the high-temperature small-particle lime entering the cooling furnace 103 from bottom to top. After completing the heat exchange with the high-temperature small-particle lime, the temperature of the cooling air rises to about 810 °C to form high-temperature hot air, which continues to pass upward through the preheating section grid 2 and then enters the preheating furnace 101 to preheat the material. After the preheating is completed, the temperature of the exhaust gas drops to about 118 °C and is discharged from the exhaust gas outlet of the preheating furnace 101.

Claims

1. A small-particle lime production system based on CO2 enrichment, the system comprising a lime kiln (1); the lime kiln (1) comprises a preheating furnace chamber (101), a suspension calcination furnace chamber (102) and a cooling furnace chamber (103); the suspension calcination furnace chamber (102) is arranged on the central axis of the lime kiln (1), and the preheating furnace chamber (101) and the cooling furnace chamber (103) are arranged around the suspension calcination furnace chamber (102); wherein, The preheating furnace chamber (101) is located in the upper outer periphery of the suspension calcination furnace chamber (102), and the cooling furnace chamber (103) is located in the lower outer periphery of the suspension calcination furnace chamber (102); a preheating section discharge opening (10101) communicating with the suspension calcination furnace chamber (102) is provided at the lower part of the preheating furnace chamber (101); a calcination section overflow opening (10201) communicating with the cooling furnace chamber (103) is provided at the upper part of the suspension calcination furnace chamber (102); a feed inlet and an exhaust gas outlet are provided on the preheating furnace chamber (101), a discharge outlet and a cooling air inlet are provided on the cooling furnace chamber (103); a flue gas inlet and a flue gas outlet are provided on the suspension calcination furnace chamber (102), and the flue gas outlet is connected to a flue gas discharge pipe (L).

2. The small particle lime production system according to claim 1, characterized in that: The system further includes a preheating section grid (2); the preheating section grid (2) is arranged at the bottom of the preheating furnace chamber (101) and above the cooling furnace chamber (103).

3. The small particle lime production system according to claim 1 or 2, characterized in that: The flue gas inlet is located at the bottom of the suspension calcination furnace chamber (102), the flue gas outlet is located at the upper part of the suspension calcination furnace chamber (102), and the flue gas discharge pipe (L) passes through the preheating furnace chamber (101); the flue gas outlet of the suspension calcination furnace chamber (102) is connected to a circulation pipeline (S1) through the flue gas discharge pipe (L), and the circulation pipeline (S1) is connected to the flue gas inlet of the suspension calcination furnace chamber (102).

4. The small particle lime production system according to claim 3, wherein: A recovery pipeline (S2) is branched off from the circulation pipeline (S1), and the recovery pipeline (S2) is connected to a CO2 recovery device (3).

5. The small particle lime production system according to any one of claims 1-2 and 4, characterized in that: The system further includes a calcination section air box (4) arranged at the flue gas inlet of the suspension calcination furnace chamber (102).

6. The small particle lime production system according to claim 3, characterized in that: The system further includes a calcination section air box (4) arranged at the flue gas inlet of the suspension calcination furnace chamber (102).

7. The small particle lime production system according to claim 5, characterized in that: A heater (5) is arranged in the calcination section air box (4).

8. The small particle lime production system according to claim 6, characterized in that: A heater (5) is arranged in the calcination section air box (4).

9. The small particle lime production system according to claim 7 or 8, characterized in that: The heater (5) is one of an electric heater, a microwave heater, and an oxygen-enriched hot air heater.

10. The small particle lime production system according to any one of claims 1-2, 4, 6-8, characterized in that: The system further includes a pallet machine (6) arranged at the preheating section discharge opening (10101).

11. The small particle lime production system according to claim 3, wherein: The system further includes a pallet machine (6) arranged at the preheating section discharge opening (10101).

12. The small particle lime production system according to claim 5, wherein: The system further includes a pallet machine (6) arranged at the preheating section discharge opening (10101).

13. The small particle lime production system according to claim 10, wherein: A passage for air flow to pass through is provided on the pallet machine (6).

14. The small particle lime production system according to claim 11 or 12, characterized in that: A passage for air flow to pass through is provided on the pallet machine (6).

15. The small-particle lime production system according to claim 10, characterized in that: A plurality of preheating section discharge openings (10101) are provided at the lower part of the preheating furnace chamber (101); the plurality of preheating section discharge openings (10101) are evenly distributed around the outer periphery of the suspension calcination furnace chamber (102); a pallet machine (6) is equipped at each preheating section discharge opening (10101); and / or A plurality of calcination section overflow openings (10201) are provided at the upper part of the suspension calcination furnace chamber (102); the plurality of calcination section overflow openings (10201) are evenly distributed around the outer periphery of the suspension calcination furnace chamber (102).

16. The small particle lime production system according to claim 11 or 12, characterized in that: The lower part of the preheating furnace chamber (101) is provided with a plurality of preheating section discharge openings (10101); the plurality of preheating section discharge openings (10101) are evenly distributed around the outer periphery of the suspension calcination furnace chamber (102); a pallet machine (6) is equipped at each preheating section discharge opening (10101); and / or The upper part of the suspension calcination furnace chamber (102) is provided with a plurality of calcination section overflow openings (10201); the plurality of calcination section overflow openings (10201) are evenly distributed around the outer periphery of the suspension calcination furnace chamber (102).

17. The small particle lime production system according to claim 4, wherein: A diverter (7) is provided at the position where the recovery pipeline (S2) branches off from the circulation pipeline (S1); a finished product fan (8) is provided on the recovery pipeline (S2) between the diverter (7) and the CO2 recovery device (3); a circulation fan (9) is provided on the circulation pipeline (S1) between the diverter (7) and the flue gas inlet of the suspension calcination furnace chamber (102); and / or The system further includes a finished product small particle lime device (10); the discharge port of the cooling furnace chamber (103) is connected to the finished product small particle lime device (10).

18. A small particle lime production process using the system according to any one of claims 1-17, the process comprising the following steps: 1) Small particle limestone material enters the preheating furnace chamber (101) of the lime kiln furnace (1) and moves downward under the action of gravity. The material completes the preheating of the preheating furnace chamber (101) during the movement; the preheated material enters the suspension calcination furnace chamber (102) through the preheating section discharge opening (10101) under the action of the pallet machine (6). The material is in a fluidized state under the action of the air flow supplied to the suspension calcination furnace chamber (102), and completes the calcination decomposition as the temperature rises, generating small particle lime and CO2 gas; 2) The small particle lime generated by decomposition moves upward under the buoyancy of the air flow, and finally flows out of the suspension calcination furnace chamber (102) from the calcination section overflow opening (10201) and enters the cooling furnace chamber (103) for cooling. After the cooling is completed, the finished product small particle lime is obtained; 3) The CO2 gas generated by decomposition enters the circulation pipeline (S1) through the flue gas discharge pipeline (L). After passing through the diverter (7) on the circulation pipeline (S1), the CO2 gas is divided into two parts. One part is transported to the CO2 recovery device (3), and the other part enters the calcination section air box (4). The heater (5) provided in the calcination section air box (4) heats this part of the CO2 gas and then sends it into the suspension calcination furnace chamber (102) to continue participating in the calcination decomposition of the small particle limestone material; 4) Cooling air is sent into the cooling furnace chamber (103) from the cooling air inlet of the cooling furnace chamber (103). The cooling air passes through the high-temperature small particle lime entering the cooling furnace chamber (103) from bottom to top. After completing the heat exchange with the high-temperature small particle lime, the temperature of the cooling air rises to form high-temperature hot air, and then continues to pass through the preheating section grille (2) upward and enters the preheating furnace chamber (101) to preheat the material. The waste gas obtained after the preheating is discharged from the waste gas outlet of the preheating furnace chamber (101).

19. The small particle lime production process according to claim 18, characterized in that: In step 1), the particle size of the small particle limestone material < 10 mm; and / or In step 1), the temperature of the preheated small-particle limestone material is 600 - 800 °C; the temperature for calcination decomposition in the suspension calcination furnace chamber (102) is 800 - 1050 °C; In step 2), the temperature of the finished small-particle lime obtained after cooling is 80 - 100 °C.

20. The small particle lime production process according to claim 19, characterized in that: In step 1), the temperature of the preheated small-particle limestone material is 650 - 750 °C; the temperature for calcination decomposition in the suspension calcination furnace chamber (102) is 900 - 1000 °C.

21. The small particle lime production process according to any one of claims 18-20, characterized in that: In step 4), the cooling air is normal-temperature air; and / or In step 3), the temperature of the CO2 gas sent into the suspension calcination furnace chamber (102) after being heated by the heat replenisher (5) is 1000 - 1100 °C; In step 4), the temperature of the high-temperature hot air formed after heat exchange with the high-temperature small-particle lime is 650 - 850 °C; the temperature of the waste gas discharged from the waste gas outlet of the preheating furnace chamber (101) after preheating is 100 - 130 °C.

22. The small particle lime production process according to claim 21, characterized in that: In step 4), the temperature of the high-temperature hot air formed after heat exchange with the high-temperature small-particle lime is 700 - 800 °C.

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