A lime kiln equipment and method for co-producing small particle CaO and high-purity CO2

Abstract

A lime kiln equipment for co-producing small-particle CaO and high-purity CO2, the lime kiln equipment comprising a lime kiln body. The lime kiln body includes a preheating chamber, a calcining chamber, and a cooling chamber. The preheating chamber and the cooling chamber are arranged on the same vertical axis, and the calcining chamber is circumferentially arranged downstream of the preheating chamber and around the cooling chamber with this axis as the center. A blanking port communicating with the calcining chamber is provided at the lower part of the preheating chamber. An overflow port is provided at the upper part of the calcining chamber near the cooling chamber, and the overflow port communicates with the cooling chamber. An air inlet and an air outlet are provided on the calcining chamber. The lime kiln body is provided with a feed port and an exhaust gas outlet on the preheating chamber, and a discharge port and a cooling air inlet on the cooling chamber. The present invention adopts an independent fluidized calcination furnace chamber, which can effectively overcome the problems of poor air permeability of small-particle limestone materials and inability to perform 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 a production method, and in particular to a lime kiln equipment and method for co-producing small particle CaO and high-purity CO2, 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. In 2020, the domestic lime output was approximately 300 million tons, with a huge industrial scale. However, at the same time, lime production will cause a large amount of CO2 emissions. According to statistics, producing 1 kg of lime will generate 1.1 kg of CO2 emissions. Based on this estimate, the total amount of CO2 emitted into the atmosphere during the lime production process in China exceeds 300 million tons / year. On the other hand, for 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 the poor air permeability of such sized materials, they 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. Against this background, developing lime production technologies and equipment with low-energy calcination of small particle lime and low CO2 emissions has become a hot and difficult point in the technical research of this field.

[0003] The double-chamber lime shaft kiln is a widely used and technically advanced industrial lime production equipment at present. It adopts a double-chamber regenerative calcination process and can obtain extremely high thermal efficiency. The heat required for the calcination link is provided by directly heating with fossil fuel combustion. The refrigerant medium in the cooling link uses normal-temperature air, and the high-temperature flue gas generated in the calcination and cooling links is used as the heat source in the preheating link. Such a process design can make full use of the flue gas waste heat and has a high fuel utilization efficiency. However, due to the mixing of the calcination flue gas and the cooling air, there are more 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 enrichment and capture technology of CO2 in the tail gas difficult and costly. As a result, the enrichment and capture of CO2 in the lime kiln tail gas is almost zero at the present stage, causing 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-chamber kiln has strict requirements for the particle size of the feeding material. Generally, it needs to be greater than 30 - 40 mm and cannot calcine fine particles less than 10 mm, resulting in a low utilization rate of the raw materials for the double-chamber 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%), and 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 is 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 thermal 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, under the new policy background, 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 CO2 enrichment and capture cost 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 tail gas of lime production under the existing equipment leads to high enrichment and capture costs, 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 shaft, the height of the material bed 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 layer. As the particle size of the material decreases, the air permeability of the bed layer drops sharply. Therefore, with the existing equipment structure, only lime materials larger than 30 - 40 mm can be processed, and small particle lime smaller than 10 mm cannot be processed, 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 due to the inability to process small particle limestone, the present invention proposes a lime kiln equipment and method for co-producing small particle CaO and high-purity CO2. In the solution of the present invention, the preheating chamber and the cooling chamber of the lime kiln body are arranged on the same vertical axis. The calcination chamber is circumferentially arranged downstream of the preheating chamber and outside the cooling chamber with this axis as the center. An overflow port communicating with the cooling chamber is provided at the upper part of the calcination chamber, and a separate air inlet and air outlet are also provided on the calcination chamber. The present invention adopts an independent fluidized bed calcination furnace chamber, which can effectively overcome the problems of poor air permeability of small particle limestone materials and inability to be calcined in a shaft furnace. At the same time, the equipment structure adopts an air flow organization form 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 lime kiln equipment for co-producing small particle CaO and high-purity CO2 is provided.

[0012] A lime kiln equipment for co-producing small particle CaO and high-purity CO2, the lime kiln equipment includes a lime kiln body. The lime kiln body includes a preheating chamber, a calcination chamber, and a cooling chamber. Among them, the preheating chamber and the cooling chamber are arranged on the same vertical axis, and the preheating chamber is located above the cooling chamber. The calcination chamber is circumferentially arranged downstream of the preheating chamber and outside the cooling chamber with the axis where the preheating chamber and the cooling chamber are located as the center. A feeding port is provided at the lower part of the preheating chamber, and the feeding port is communicated with the calcination chamber. An overflow port is provided at the upper part of the calcination chamber near the cooling chamber, and the overflow port is communicated with the cooling chamber. An air inlet and an air outlet are provided on the calcination chamber. The lime kiln body is provided with a feeding port and an exhaust gas outlet on the preheating chamber, and a discharging port and a cooling air inlet on the cooling chamber.

[0013] Preferably, the lime kiln equipment further includes a calcination section inlet valve provided at the feeding port of the preheating chamber.

[0014] Preferably, the lime kiln equipment further includes a baffle plate provided at the bottom of the preheating chamber. The baffle plate is located above the overflow port.

[0015] In the present invention, the air inlet of the calcination chamber is located at the lower part or the bottom of the calcination chamber, and the air outlet is located at the upper part or the top of the calcination chamber. The heat recovery pipeline led out from the air outlet of the calcination chamber is connected to the air inlet of the calcination chamber. A circulation fan is provided on the heat recovery pipeline.

[0016] Preferably, a CO2 recovery pipeline is branched out from the heat recovery pipeline at a position upstream of the circulation fan, and the CO2 recovery pipeline is connected to the finished product CO2 system. A finished product fan is provided on the CO2 recovery pipeline.

[0017] In the present invention, the lime kiln equipment further includes a calcination chamber air box. The calcination chamber air box is arranged at the air inlet of the calcination chamber. Preferably, an electric reheater is provided in the calcination chamber air box. More preferably, a rectifier is provided at the top of the calcination chamber air box.

[0018] In the present invention, the lime kiln equipment further includes a preheating chamber air box. The preheating chamber air box is arranged at the bottom of the preheating chamber and above the cooling chamber. A lower inlet is provided on the bottom surface of the preheating chamber air box, and uniformly distributed openings are provided on the upper surface of the preheating chamber air box.

[0019] Preferably, the lime kiln equipment further includes a cooling section inlet valve arranged at the overflow port. The cooling section inlet valve cooperates with the baffle plate.

[0020] Preferably, a diverter is provided at the position where the CO2 recovery pipeline is branched out from the heat recovery pipeline.

[0021] Preferably, the lime kiln equipment further includes a finished product small particle CaO system arranged downstream of the lime kiln body. The discharge port of the lime kiln body is connected to the finished product small particle CaO system.

[0022] According to the second embodiment of the present invention, a method for co-producing small particle CaO and high-purity CO2 is provided.

[0023] A method for co-producing small particle CaO and high-purity CO2 or a method using the lime kiln equipment described in the first embodiment, the method includes the following steps:

[0024] 1) Small particle limestone materials enter the preheating chamber from the feed port of the lime kiln body, and the materials flow downward under the action of gravity. The materials are first preheated in the preheating chamber, and the preheated materials enter the calcination chamber via the calcination section inlet valve. The materials entering the calcination chamber are in a suspended boiling state under the action of the air flow supplied by the calcination chamber air box, and are calcined and decomposed during the movement process to generate small particle CaO and CO2 gas.

[0025] 2) Since the limestone material decomposes to form CaO, the density of the material becomes smaller. Therefore, the high-temperature small particles of CaO produced by calcination move upward under the action of the air flow. Finally, the high-temperature small particles of CaO flow out from the overflow port at the upper part of the calcination chamber and enter the cooling chamber for cooling to obtain the finished small particles of CaO. Preferably, the finished small particles of CaO are transported to the finished small particles of CaO system.

[0026] 3) The cooling air enters the cooling chamber from the cooling air inlet of the lime kiln body. The upward cooling air and the high-temperature small particles of CaO moving downward in the cooling chamber conduct countercurrent heat exchange. After the heat exchange is completed, the high-temperature waste gas is enriched at the top of the cooling chamber and then enters from the lower inlet of the preheating chamber air box and flows into the preheating chamber through the uniform openings on the upper surface of the preheating chamber air box. The high-temperature waste gas is discharged from the waste gas outlet on the preheating chamber after exchanging heat with the material in the preheating chamber and cooling down. Preferably, the waste gas after heat exchange and cooling is transported to the waste heat utilization device.

[0027] 4) The high-temperature CO2 gas generated by calcination flows through the regenerative pipeline and is split into two parts after passing through the shunt. One part of the high-temperature CO2 gas is sent into the calcination chamber air box through the circulation fan. The high-temperature CO2 gas circulating into the calcination chamber air box is heated by the electric heater, and then sent into the calcination chamber after being rectified by the rectifier, which is used to fluidize the material in the calcination chamber and supply heat to complete the decomposition. The other part of the high-temperature CO2 gas (after waste heat utilization) is sent into the finished product CO2 system through the finished product fan.

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

[0029] In the present invention, in step 3), the cooling air is normal temperature air. The temperature of the normal temperature air is generally 15°C to 25°C, such as 20°C or 25°C.

[0030] In the present invention, in step 1), the temperature of the preheated material is 600 - 800°C, preferably 650 - 750°C. The temperature of the calcination decomposition in the calcination chamber is 800 - 1050°C, preferably 900 - 1000°C.

[0031] In step 2), the temperature of the finished small particles of CaO obtained after cooling is 80 - 100°C.

[0032] In step 3), the temperature of the high-temperature waste gas enriched at the top of the cooling chamber is 650 - 850°C, preferably 700 - 800°C. The temperature of the waste gas discharged from the waste gas outlet on the preheating chamber is 100 - 130°C.

[0033] In step 4), the temperature of the high-temperature CO2 gas entering the calcination chamber air box after heat supplement is 1000 - 1100°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 fail to meet the requirements for feeding into the existing vertical kilns or rotary kilns 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 CO2 in the tail gas due to the low concentration of CO2 in the tail gas, thus causing serious greenhouse gas emissions and waste of resources. To address these technical problems, the present invention proposes a lime kiln equipment and method for co-producing small-particle CaO and high-purity CO2. In the solution of the present invention, the preheating chamber and the cooling chamber of the lime kiln body are arranged on the same vertical axis. The calcination chamber is circumferentially arranged downstream of the preheating chamber and outside the cooling chamber with this axis as the center. An overflow port communicating with the cooling chamber is provided at the upper part of the calcination chamber, and a separate air inlet and air outlet are also provided on the calcination chamber. The present invention adopts an independent fluidized-bed calcination furnace chamber, which can effectively overcome the problems of poor air permeability of small-particle limestone materials and inability to be calcined in a shaft furnace. At the same time, the equipment structure adopts an air flow organization form in which the cooling-preheating air flow is separated from the calcination air flow, enabling the preparation of high-purity CO2 gas and effectively recovering the CO2 gas in the lime production process, thereby avoiding carbon emissions and resource waste in the lime production process.

[0035] In the present invention, the lime kiln equipment for co-producing small-particle CaO and high-purity CO2 includes a lime kiln body, which further includes a preheating chamber, a calcination chamber, and a cooling chamber. Different from the existing lime production equipment in which the preheating, calcination, and cooling processes are carried out in series in the same vertical chamber, in this application, the preheating chamber and the cooling chamber are arranged on the same vertical axis (the central axis of the lime kiln body), and the calcination chamber is circumferentially arranged downstream of the preheating chamber and outside the cooling chamber with the axis where the preheating chamber and the cooling chamber are located as the center, that is, the calcination chamber and the preheating chamber (or the cooling chamber) are not in the same vertical chamber. Such a setting can reduce the height of the material layer and improve the air permeability of the material, so that small-particle materials with a size less than 10 mm can meet the requirements for feeding into the kiln. A blanking port communicating with the calcination chamber is provided at the lower part of the preheating chamber, and an overflow port communicating with the cooling chamber is provided at the upper part of the calcination chamber. An inlet and an outlet are provided on the lime kiln body. Generally, the inlet and the exhaust gas outlet are arranged at the top or upper part of the preheating chamber, and the discharge port and the cooling air inlet are arranged at the bottom or lower part of the cooling chamber. A separate air inlet and air outlet are also opened on the calcination chamber to provide air flow for the calcination chamber as an independent fluidized-bed calcination furnace chamber, further overcoming the problems of poor air permeability of small-particle limestone materials and inability to be calcined in a shaft furnace; at the same time, this structural setting separates the calcination air flow (high-purity CO2) from the cooling-preheating air flow, avoiding the dilution of the high-concentration CO2 gas in the calcination chamber by the cooling air, that is, obtaining a high-purity CO2 gas by-product while producing lime.

[0036] As a preferred solution, the lime kiln equipment in the present invention further includes a calcination section inlet valve provided at the blanking port of the preheating chamber. The calcination section inlet valve is used to control the flow of the preheated material from the blanking port of the preheating chamber into the calcination chamber. When the small particle limestone material is preheated in the preheating chamber, that is, when the preheating temperature of the material reaches the requirement (for example, the temperature of the preheated material reaches about 700 °C), the calcination section inlet valve is opened at this time, and the preheated material in the preheating chamber can flow into the calcination chamber to carry out the next stage of calcination. When all the preheated material has flowed into the calcination chamber, the calcination section inlet valve is closed at this time. On the one hand, the preheating chamber can be refilled with material to start the next round of preheating process. At the same time, it can also prevent the gas flow in the calcination chamber from entering the preheating chamber. That is to say, the setting of the calcination section inlet valve can realize the one-way flow of the material from the preheating chamber to the calcination chamber and prevent the flue gas from flowing back from the calcination chamber into the preheating chamber.

[0037] Further preferably, the present invention further includes a baffle plate provided at the bottom of the preheating chamber, and the baffle plate is located above the overflow port. A cooling section inlet valve is also provided at the overflow port. The baffle plate and the cooling section inlet valve cooperate with each other to realize the one-way flow of the material from the calcination chamber to the cooling chamber and prevent the flue gas from flowing from the cooling chamber into the calcination chamber. During the lime production process, the preheated small particle limestone material enters the calcination chamber from the blanking port of the preheating chamber. In the calcination chamber, the small particle material is in a suspended boiling state under the action of the air flow (entering the calcination chamber from the air inlet), and gradually heats up and decomposes during this process. The calcium oxide obtained by decomposition has a smaller density (the density of the main component CaCO3 of limestone is about 2700 kg / m 3 , and the density of CaO is about 1500 kg / m 3 ), and moves upward under the action of the air flow, overflows to the cooling chamber through the overflow port, and the finished small particle calcium oxide is obtained after cooling. Under the control of the baffle plate and the cooling section inlet valve, and at the same time because the calcination chamber is in a fluidized state, that is, the pressure in the calcination chamber is greater than that in the cooling chamber, the hot air formed after the cooling air exchanges heat with the high-temperature calcium oxide when entering the cooling chamber will not flow back from the overflow port into the calcination chamber, but directly enters the preheating chamber upward, thus preventing the cooling air from diluting the high-concentration CO2 gas in the calcination chamber, and then realizing the preparation of high-purity CO2 gas and subsequent resource utilization, and avoiding carbon emissions and resource waste in the lime production process.

[0038] It should be noted that for this application to solve the problem of small - particle limestone material being calcined in the kiln, the calcination chamber air velocity is the air velocity at which small - particle limestone material (mainly composed of CaCO3) is suspended and fluidized in the calcination chamber. When the small - particle limestone material is calcined and decomposed into CaO, the density of CaO is reduced compared to that of CaCO3. Therefore, CaO moves upward under the action of the airflow in the calcination chamber and enters the cooling chamber through the overflow port, that is, the calcination chamber air velocity is greater than the suspension air velocity of CaO; CaO needs to settle in the cooling chamber and then be discharged through the discharge port to obtain the finished lime. Therefore, the cooling chamber air velocity should be less than the suspension air velocity of CaO, that is, the cooling chamber air velocity should be much less than the calcination chamber air velocity, namely V 冷却 <V CaO悬浮 <V 煅烧 , thus realizing the state where CaO suspends and rises in the calcination chamber and settles in the cooling chamber.

[0039] In the present invention, the heat required for the calcination chamber to calcine and decompose the material is mainly supplied by the self - circulation of the high - temperature flue gas generated in the calcination process, which can avoid introducing impurity components such as O2 and N2 during the calcination heat supply process and further improve the purity of CO2 gas in the calcination chamber. In the present invention, a calcination chamber air box is provided at the bottom of the calcination chamber, an electric heater is provided in the calcination chamber air box, and a rectifier is provided at the connection between the upper part of the calcination chamber air box and the bottom of the calcination chamber. 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 material, the high - temperature calcination flue gas discharged from the air outlet of the calcination chamber first passes through the electric heater in the calcination chamber air box to be heated and raised in temperature, and then is evenly sent into the calcination chamber through the rectifier to supply heat for the calcination and decomposition of the material in the calcination chamber. At the same time, this part of the circulating flue gas also provides the air flow for the fluidization of the material in the calcination chamber. By controlling parameters such as the flow velocity and flow rate of the air flow sent from the calcination chamber air box into the calcination chamber, the fluidization of the material with corresponding particle size can be satisfied, making the material in a suspended boiling state.

[0040] The cooling air enters the cooling chamber to exchange heat with the high - temperature calcium oxide generated by decomposition. After the heat exchange, the high - temperature waste gas enters the pre - heating chamber upward to pre - heat the material. To better convey the pre - heating air flow and achieve uniform pre - heating of the material, a pre - heating chamber air box is provided at the bottom of the pre - heating chamber in the present invention. It should be noted that the baffle plate is provided at the bottom of the pre - heating chamber air box and is connected to the bottom plate of the pre - heating chamber air box. The bottom surface of the pre - heating chamber air box is provided with a lower inlet, and the upper surface is provided with uniformly distributed and array - arranged openings. The high - temperature waste gas discharged from the cooling chamber enters from the lower inlet of the pre - heating chamber air box, forms a certain pressure in the cavity of the pre - heating chamber air box, and flows into the pre - heating chamber through the uniform openings on the upper surface.

[0041] In this application, a diverter is added to the exhaust pipe (i.e., the recuperation pipeline) of the calcination flue gas to divert the high-temperature flue gas generated by calcination and decomposition in the calcination chamber. 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 calcination chamber and directly enters the preheating chamber to preheat the material. Based on this, the lime kiln equipment 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 material, and the calcination flue gas is used for calcination heating 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, using the device of this application can obtain high-purity CO2 gas while producing lime, avoiding carbon emissions and resource waste in the existing lime production process. Moreover, the lime kiln equipment in this application adopts an independent fluidized calcination furnace chamber, and the small-particle limestone material is in a suspended boiling state in the calcination chamber, greatly increasing the heat transfer intensity between the small-particle limestone material and the heat exchange medium, and effectively overcoming the problems of poor air permeability and uneven calcination of small-particle materials.

[0042] When producing lime using the lime kiln equipment for co-producing small-particle CaO and high-purity CO2 described in the present invention, during the production process, small-particle (<10mm) limestone (main component CaCO3) material is fed into the preheating chamber through the feed inlet. After passing through the preheating chamber, the temperature rises from room temperature to about 700 °C, and the preheated material enters the calcination chamber from the discharge opening. The material in the calcination chamber is in a suspended boiling state under the action of the air flow. During the process of the material moving from the top to the bottom of the calcination chamber, the temperature further rises to about 1050 °C and a decomposition reaction occurs, generating CaO and releasing CO2. The calcium oxide that has completed the reaction has a smaller density (the density of CaCO3 is about 2700 kg / m 3 , and the density of CaO is about 1500 kg / m 3) Under the action of the air flow, it moves upward and finally flows out of the overflow port at the upper part of the calcination chamber and enters the cooling chamber. The high-temperature CO2 gas generated by calcination flows through the recuperation pipeline and passes through the diverter. At the diverter, it is divided into two parts. After a part of the CO2 gas is extracted by the finished product fan, it is sent to the finished product CO2 system, and the remaining CO2 gas is sent to the calcination chamber air box by the circulation fan. The CO2 circulated into the calcination chamber air box is heated up to about 1100 °C by the electric supplementary heater, and then rectified by the rectifier and sent into the calcination chamber from the bottom of the calcination chamber to fluidize the materials in the calcination chamber and supply heat. During the downward movement of the materials entering the cooling chamber, they exchange heat with the cooling air sent from the bottom of the cooling chamber, and the temperature gradually drops below 100 °C. Finally, they are discharged from the bottom of the cooling chamber to form finished small particle CaO, which is sent into the finished small particle CaO system. After heat exchange, the high-temperature waste gas (about 800 °C) is concentrated at the top of the cooling chamber, enters the air box from the lower inlet of the preheating chamber air box, and evenly flows into the preheating chamber through the openings on the upper surface of the air box. After passing through the preheating chamber material layer and exchanging heat with the materials, the temperature drops to about 120 °C and then is discharged from the waste gas outlet at the top of the preheating chamber.

[0043] In this application, the waste gas discharged from the waste gas outlet after preheating the materials can be transported to the waste heat utilization device for further utilization of the waste heat. The high-temperature CO2 gas separated after flowing out of the calcination chamber can also be transported to the finished product CO2 system after waste heat utilization to complete the collection and resource utilization of CO2.

[0044] Compared with the prior art, the present invention has the following beneficial technical effects:

[0045] 1. The present invention adopts an independent fluidized calcination furnace chamber. The small particle limestone materials are in a suspended boiling state in the calcination chamber, greatly improving the heat transfer intensity between the small particle limestone materials and the heat exchange medium, effectively overcoming the problems of poor air permeability of small particle materials and inability to be calcined in a shaft furnace, and avoiding the waste of resources of small particle limestone raw materials.

[0046] 2. The present invention arranges the preheating chamber and the cooling chamber on the same vertical axis. The calcination chamber is circumferentially arranged downstream of the preheating chamber and outside the cooling chamber with this axis as the center. An overflow port communicating with the cooling chamber is provided at the upper part of the calcination chamber, and a separate air inlet and air outlet are also provided on the calcination chamber. Through such a structural setting, the two air flows 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.

[0047] 3. The present invention diverts the calcination flue gas. A part of it is used as a heat carrier to circulate and supply heat in the calcination chamber. The calcination flue gas circulates by itself to provide heat for the calcination and decomposition of the materials in the calcination chamber. That is, while ensuring the utilization rate of the waste heat of the flue gas, it avoids introducing impurity components such as O2 and N2 during the calcination heat supply process, further improving the purity of 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

[0048] Figure 1 FIG. is a schematic structural diagram of a lime kiln device for co-producing small-particle CaO and high-purity CO2 according to the present invention;

[0049] Figure 2 FIG. is a schematic structural diagram of a lime production device in the prior art.

[0050] Reference Numerals:

[0051] A: Lime kiln body; A1: Preheating chamber; A2: Calcination chamber; A3: Cooling chamber; 1: Overflow port; 2: Inlet valve of the calcination section; 3: Baffle plate; 4: Circulation fan; 5: Finished product CO2 system; 6: Finished product fan; 7: Calcination chamber air box; 8: Electric reheater; 9: Rectifier; 10: Preheating chamber air box; 11: Inlet valve of the cooling section; 12: Shunt; 13: Finished product small-particle CaO system;

[0052] L1: Regenerative pipeline; L2: CO2 recovery pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] 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.

[0054] According to the first embodiment of the present invention, a lime kiln device for co-producing small-particle CaO and high-purity CO2 is provided.

[0055] A lime kiln equipment for co-producing small-particle CaO and high-purity CO2, the lime kiln equipment includes a lime kiln body A. The lime kiln body A includes a preheating chamber A1, a calcination chamber A2, and a cooling chamber A3. Among them, the preheating chamber A1 and the cooling chamber A3 are arranged on the same vertical axis, and the preheating chamber A1 is located above the cooling chamber A3. The calcination chamber A2 is circumferentially arranged downstream of the preheating chamber A1 and around the cooling chamber A3 with the axis where the preheating chamber A1 and the cooling chamber A3 are located as the center. A feeding port is provided at the lower part of the preheating chamber A1, and the feeding port is communicated with the calcination chamber A2. An overflow port 1 is provided at the upper part of the calcination chamber A2 near the cooling chamber A3, and the overflow port 1 is communicated with the cooling chamber A3. An air inlet and an air outlet are provided on the calcination chamber A2. The lime kiln body A is provided with a feeding port and an exhaust gas outlet on the preheating chamber A1, and a discharging port and a cooling air inlet on the cooling chamber A3.

[0056] Preferably, the lime kiln equipment further includes a calcination section inlet valve 2 provided at the feeding port of the preheating chamber A1.

[0057] Preferably, the lime kiln equipment further includes a baffle plate 3 provided at the bottom of the preheating chamber A1. The baffle plate 3 is located above the overflow port 1.

[0058] In the present invention, the air inlet of the calcination chamber A2 is located at the lower part or the bottom of the calcination chamber A2, and the air outlet is located at the upper part or the top of the calcination chamber A2. The regenerative pipeline L1 led out from the air outlet of the calcination chamber A2 is connected to the air inlet of the calcination chamber A2. A circulation fan 4 is provided on the regenerative pipeline L1.

[0059] Preferably, a CO2 recovery pipeline L2 is branched out from the regenerative pipeline L1 at a position upstream of the circulation fan 4, and the CO2 recovery pipeline L2 is connected to a finished product CO2 system 5. A finished product fan 6 is provided on the CO2 recovery pipeline L2.

[0060] In the present invention, the lime kiln equipment further includes a calcination chamber air box 7. The calcination chamber air box 7 is provided at the air inlet of the calcination chamber A2. Preferably, an electric reheater 8 is provided in the calcination chamber air box 7. Further preferably, a rectifier 9 is provided at the top of the calcination chamber air box 7.

[0061] In the present invention, the lime kiln equipment further includes a preheating chamber air box 10. The preheating chamber air box 10 is provided at the bottom of the preheating chamber A1 and above the cooling chamber A3. The bottom surface of the preheating chamber air box 10 is provided with a lower inlet, and the upper surface of the preheating chamber air box 10 is provided with uniformly distributed openings.

[0062] Preferably, the lime kiln equipment further includes a cooling section inlet valve 11 provided at the overflow port 1. The cooling section inlet valve 11 cooperates with the baffle plate 3.

[0063] Preferably, a diverter 12 is provided at the position where the CO2 recovery pipeline L2 branches off from the regenerative pipeline L1.

[0064] Preferably, the lime kiln equipment further includes a finished small particle CaO system 13 provided downstream of the lime kiln body A. The discharge port of the lime kiln body A is connected to the finished small particle CaO system 13.

[0065] Example 1

[0066] As Figure 1 shown, a lime kiln equipment for co-producing small particle CaO and high-purity CO2 includes a lime kiln body A. The lime kiln body A includes a preheating chamber A1, a calcining chamber A2, and a cooling chamber A3. Among them, the preheating chamber A1 and the cooling chamber A3 are arranged on the same vertical axis, and the preheating chamber A1 is located above the cooling chamber A3. The calcining chamber A2 is circumferentially arranged downstream of the preheating chamber A1 and around the cooling chamber A3 with the axis where the preheating chamber A1 and the cooling chamber A3 are located as the center. A feeding port is provided at the lower part of the preheating chamber A1, and the feeding port is communicated with the calcining chamber A2. An overflow port 1 is provided at the upper part of the calcining chamber A2 near the cooling chamber A3, and the overflow port 1 is communicated with the cooling chamber A3. An air inlet and an air outlet are provided on the calcining chamber A2. The lime kiln body A is provided with a feeding port and an exhaust gas outlet on the preheating chamber A1, and a discharge port and a cooling air inlet on the cooling chamber A3.

[0067] Example 2

[0068] Repeat Example 1, except that the lime kiln equipment further includes a calcining section inlet valve 2 provided at the feeding port of the preheating chamber A1.

[0069] Example 3

[0070] Repeat Example 2, except that the lime kiln equipment further includes a baffle plate 3 provided at the bottom of the preheating chamber A1. The baffle plate 3 is located above the overflow port 1.

[0071] Example 4

[0072] Repeat Example 3, except that the air inlet of the calcining chamber A2 is located at the bottom of the calcining chamber A2, and the air outlet is located at the upper part of the calcining chamber A2. The regenerative pipeline L1 led out from the air outlet of the calcining chamber A2 is connected to the air inlet of the calcining chamber A2. A circulation fan 4 is provided on the regenerative pipeline L1.

[0073] Example 5

[0074] Repeat Example 4, except that a CO2 recovery pipeline L2 is branched off from the regenerative pipeline L1 at a position upstream of the circulation fan 4, and the CO2 recovery pipeline L2 is connected to the finished CO2 system 5. A finished product fan 6 is provided on the CO2 recovery pipeline L2.

[0075] Example 6

[0076] Repeat Example 5, except that the lime kiln equipment further includes a calcining chamber air box 7. The calcining chamber air box 7 is arranged at the air inlet of the calcining chamber A2.

[0077] Example 7

[0078] Repeat Example 6, except that an electric heater 8 is provided in the calcining chamber air box 7.

[0079] Example 8

[0080] Repeat Example 7, except that a rectifier 9 is provided at the top of the calcining chamber air box 7.

[0081] Example 9

[0082] Repeat Example 8, except that the lime kiln equipment further includes a preheating chamber air box 10. The preheating chamber air box 10 is arranged at the bottom of the preheating chamber A1 and above the cooling chamber A3. The bottom surface of the preheating chamber air box 10 is provided with a lower inlet, and the upper surface of the preheating chamber air box 10 is provided with uniformly distributed openings. At this time, the baffle plate 3 is arranged at the bottom of the preheating chamber air box 10 and is connected to the bottom plate of the preheating chamber air box 10.

[0083] Example 10

[0084] Repeat Example 9, except that the lime kiln equipment further includes a cooling section inlet valve 11 arranged at the overflow port 1. The cooling section inlet valve 11 cooperates with the baffle plate 3.

[0085] Example 11

[0086] Repeat Example 10, except that a diverter 12 is provided at the position where the CO2 recovery pipeline L2 is branched from the regenerative pipeline L1.

[0087] Example 12

[0088] Repeat Example 11, except that the lime kiln equipment further includes a finished small particle CaO system 13 arranged downstream of the lime kiln body A. The discharge port of the lime kiln body A is connected to the finished small particle CaO system 13.

[0089] Example 13

[0090] A method for co-producing small particle CaO and high-purity CO2, the method comprising the following steps:

[0091] 1) Small granular limestone material enters the preheating chamber A1 from the feed inlet of the lime kiln body A, and the material flows downward under the action of gravity. The material is first preheated in the preheating chamber A1, and the preheated material enters the calcination chamber A2 through the calcination section inlet valve 2. The material entering the calcination chamber A2 is in a suspended boiling state under the action of the air flow supplied by the calcination chamber air box 7, and is calcined and decomposed during the movement process to generate small granular CaO and CO2 gas.

[0092] 2) Since the limestone material decomposes to generate CaO, the material density becomes smaller. Therefore, the high-temperature small granular CaO generated by calcination moves upward under the action of the air flow, and finally the high-temperature small granular CaO flows out from the overflow port 1 at the upper part of the calcination chamber A2 and enters the cooling chamber A3 for cooling to obtain the finished small granular CaO.

[0093] 3) The cooling air enters the cooling chamber A3 from the cooling air inlet of the lime kiln body A. The upward cooling air and the high-temperature small granular CaO moving downward in the cooling chamber A3 perform countercurrent heat exchange. After the heat exchange is completed, the high-temperature waste gas is enriched at the top of the cooling chamber A3, enters from the lower inlet of the preheating chamber air box 10, and flows into the preheating chamber A1 through the uniform openings on the upper surface of the preheating chamber air box 10. The high-temperature waste gas is discharged from the waste gas outlet on the preheating chamber A1 after exchanging heat with the material in the preheating chamber A1 and cooling down.

[0094] 4) The high-temperature CO2 gas generated by calcination flows through the recuperation pipeline L1 and passes through the diverter 12 and is divided into two parts. One part of the high-temperature CO2 gas is sent into the calcination chamber air box 7 through the circulation fan 4. The high-temperature CO2 gas circulating into the calcination chamber air box 7 is heated by the electric heater 8, and then sent into the calcination chamber A2 after being rectified by the rectifier 9, which is used to fluidize the material in the calcination chamber A2 and supply heat to complete the decomposition. The other part of the high-temperature CO2 gas is sent into the finished product CO2 system 5 through the finished product fan 6.

[0095] Example 14

[0096] A method for co-producing small granular CaO and high-purity CO2, using the lime kiln equipment described in Example 12, the method includes the following steps:

[0097] 1) Small granular limestone material with a particle size < 10 mm enters the preheating chamber A1 from the feed inlet of the lime kiln body A, and the material flows downward under the action of gravity. The material is first preheated in the preheating chamber A1, and the temperature rises from room temperature to about 700 °C. The preheated material enters the calcination chamber A2 through the calcination section inlet valve 2. The material entering the calcination chamber A2 is in a suspended boiling state under the action of the air flow supplied by the calcination chamber air box 7, and the temperature rises to about 1050 °C during the movement process to complete the calcination decomposition, generating small granular CaO and CO2 gas.

[0098] 2) Since the limestone material decomposes to form CaO, the material density decreases. Therefore, the high-temperature small particles of CaO produced by calcination move upward under the action of the air flow. Finally, the high-temperature small particles of CaO flow out from the overflow port 1 at the upper part of the calcination chamber A2 and enter the cooling chamber A3 for cooling. The temperature drops below 100 °C to obtain the finished small particles of CaO. The finished small particles of CaO are transported to the finished small particles of CaO system 13.

[0099] 3) Normal temperature air enters the cooling chamber A3 as the cooling air from the cooling air inlet of the lime kiln body A. The upward cooling air and the high-temperature small particles of CaO moving downward in the cooling chamber A3 conduct countercurrent heat exchange. After the heat exchange, the temperature of the high-temperature waste gas is about 800 °C. After the high-temperature waste gas is enriched at the top of the cooling chamber A3, it enters from the lower inlet of the preheating chamber air box 10 and flows into the preheating chamber A1 through the uniform openings on the upper surface of the preheating chamber air box 10. The high-temperature waste gas is discharged from the waste gas outlet on the preheating chamber A1 after the heat exchange and temperature reduction to about 120 °C with the material in the preheating chamber A1. The waste gas after heat exchange and temperature reduction is transported to the waste heat utilization device.

[0100] 4) The high-temperature CO2 gas produced by calcination flows through the regenerative pipeline L1 and passes through the diverter 12 and then divides into two parts. One part of the high-temperature CO2 gas is sent to the calcination chamber air box 7 through the circulation fan 4. The high-temperature CO2 gas circulating into the calcination chamber air box 7 is heated up to about 1100 °C by the electric supplementary heater 8, and then sent into the calcination chamber A2 after being rectified by the rectifier 9 to fluidize the material in the calcination chamber A2 and supply heat to complete the decomposition. The other part of the high-temperature CO2 gas is sent to the finished CO2 system 5 through the finished product fan 6 after the waste heat is utilized.

Claims

1. A lime kiln equipment for co-producing small particle CaO and high-purity CO2, characterized in that: This lime kiln equipment includes a lime kiln body (A); the lime kiln body (A) includes a preheating chamber (A1), a calcination chamber (A2), and a cooling chamber (A3); among them, the preheating chamber (A1) and the cooling chamber (A3) are arranged on the same vertical axis, and the preheating chamber (A1) is located above the cooling chamber (A3); the calcination chamber (A2) is circumferentially arranged downstream of the preheating chamber (A1) and around the cooling chamber (A3) with the axis where the preheating chamber (A1) and the cooling chamber (A3) are located as the center; a feeding port is provided at the lower part of the preheating chamber (A1), and the feeding port is communicated with the calcination chamber (A2); an overflow port (1) is provided at the upper part of the calcination chamber (A2) near the cooling chamber (A3), and the overflow port (1) is communicated with the cooling chamber (A3); an air inlet and an air outlet are provided on the calcination chamber (A2); the lime kiln body (A) is provided with a feeding port and an exhaust gas outlet on the preheating chamber (A1), and a discharging port and a cooling air inlet on the cooling chamber (A3).

2. The lime kiln equipment according to claim 1, characterized in that: This lime kiln equipment further includes a calcination section inlet valve (2) provided at the feeding port of the preheating chamber (A1); and / or This lime kiln equipment further includes a baffle plate (3) provided at the bottom of the preheating chamber (A1); the baffle plate (3) is located above the overflow port (1).

3. The lime kiln equipment according to claim 1 or 2, characterized in that: The air inlet of the calcination chamber (A2) is located at the lower part or the bottom of the calcination chamber (A2), and the air outlet is located at the upper part or the top of the calcination chamber (A2); a heat regeneration pipeline (L1) led out from the air outlet of the calcination chamber (A2) is connected to the air inlet of the calcination chamber (A2); a circulation fan (4) is provided on the heat regeneration pipeline (L1).

4. The lime kiln equipment according to claim 3, characterized in that: A CO2 recovery pipeline (L2) is branched out from the heat regeneration pipeline (L1) at a position upstream of the circulation fan (4), and the CO2 recovery pipeline (L2) is connected to a finished product CO2 system (5); a finished product fan (6) is provided on the CO2 recovery pipeline (L2).

5. The lime kiln equipment according to any one of claims 1, 2, and 4, characterized in that: This lime kiln equipment further includes a calcination chamber air box (7); the calcination chamber air box (7) is provided at the air inlet of the calcination chamber (A2).

6. The lime kiln equipment according to claim 3, characterized in that: This lime kiln equipment further includes a calcination chamber air box (7); the calcination chamber air box (7) is provided at the air inlet of the calcination chamber (A2).

7. The lime kiln equipment according to claim 5, characterized in that: An electric heater (8) is provided in the calcination chamber air box (7).

8. The lime kiln equipment according to claim 6, characterized in that: An electric heater (8) is provided in the calcination chamber air box (7).

9. The lime kiln equipment according to claim 7 or 8, characterized in that: A rectifier (9) is provided at the top of the calcination chamber air box (7).

10. The lime kiln equipment according to any one of claims 1, 2, 4, 6-8, characterized in that: This lime kiln equipment further includes a preheating chamber air box (10); the preheating chamber air box (10) is provided at the bottom of the preheating chamber (A1) and above the cooling chamber (A3); a lower inlet is provided on the bottom surface of the preheating chamber air box (10), and uniformly distributed openings are provided on the upper surface of the preheating chamber air box (10).

11. The lime kiln equipment according to claim 3, characterized in that: This lime kiln equipment further includes a preheating chamber air box (10); the preheating chamber air box (10) is provided at the bottom of the preheating chamber (A1) and above the cooling chamber (A3); a lower inlet is provided on the bottom surface of the preheating chamber air box (10), and uniformly distributed openings are provided on the upper surface of the preheating chamber air box (y).

12. The lime kiln equipment according to claim 5, characterized in that: The lime kiln equipment further includes a preheating chamber air box (10); the preheating chamber air box (10) is arranged at the bottom of the preheating chamber (A1) and above the cooling chamber (A3); the bottom surface of the preheating chamber air box (10) is provided with a lower inlet, and the upper surface of the preheating chamber air box (10) is provided with evenly distributed openings.

13. The lime kiln equipment according to claim 2, characterized in that: The lime kiln equipment further includes a cooling section inlet valve (11) arranged at the overflow port (1); the cooling section inlet valve (11) cooperates with the baffle plate (3).

14. The lime kiln equipment according to claim 3, characterized in that: A diverter (12) is provided at the position where the CO2 recovery pipeline (L2) branches off from the regenerative pipeline (L1); and / or The lime kiln equipment further includes a finished small particle CaO system (13) arranged downstream of the lime kiln body (A); the discharge port of the lime kiln body (A) is connected to the finished small particle CaO system (13).

15. A method of using the lime kiln equipment according to any one of claims 1-14, the method comprising the following steps: 1) Small particle limestone material enters the preheating chamber (A1) from the feed port of the lime kiln body (A), and the material flows downward under the action of gravity; the material is first preheated in the preheating chamber (A1), and the preheated material enters the calcination chamber (A2) via the calcination section inlet valve (2); the material entering the calcination chamber (A2) is in a suspended boiling state under the action of the air flow supplied by the calcination chamber air box (7), and is calcined and decomposed during the movement process to generate small particle CaO and CO2 gas; 2) Since the limestone material decomposes to generate CaO, the material density becomes smaller, so the high-temperature small particle CaO generated by calcination moves upward under the action of the air flow, and finally the high-temperature small particle CaO flows out from the overflow port (1) at the upper part of the calcination chamber (A2) and enters the cooling chamber (A3) for cooling to obtain finished small particle CaO; 3) Cooling air enters the cooling chamber (A3) from the cooling air inlet of the lime kiln body (A), and the upward cooling air and the high-temperature small particle CaO moving downward in the cooling chamber (A3) perform countercurrent heat exchange. After the heat exchange is completed, the high-temperature waste gas is enriched at the top of the cooling chamber (A3), enters from the lower inlet of the preheating chamber air box (10), and flows into the preheating chamber (A1) through the evenly distributed openings on the upper surface of the preheating chamber air box (10). The high-temperature waste gas is discharged from the waste gas outlet on the preheating chamber (A1) after exchanging heat with the material in the preheating chamber (A1) and cooling down; 4) The high-temperature CO2 gas generated by calcination flows through the diverter (12) through the regenerative pipeline (L1) and is divided into two parts. One part of the high-temperature CO2 gas is sent into the calcination chamber air box (7) by the circulation fan (4), and the high-temperature CO2 gas circulating into the calcination chamber air box (7) is heated by the electric heater (8), and then sent into the calcination chamber (A2) after being rectified by the rectifier (9) to fluidize the material in the calcination chamber (A2) and supply heat to complete the decomposition; the other part of the high-temperature CO2 gas is sent into the finished product CO2 system (5) by the finished product fan (6).

16. The method according to claim 15, characterized in that: In step 2), the finished small particle CaO is transported to the finished small particle CaO system (13).

17. The method according to claim 15, wherein: In step 2), the waste gas after heat exchange and cooling is transported to the waste heat utilization device.

18. The method according to claim 15, characterized in that: In step 1), the particle size of the small particle limestone material < 10 mm; and / or In step 3), the cooling air is normal temperature air.

19. The method according to any one of claims 15 - 18, characterized in that: In step 1), the temperature of the preheated material is 600 - 800 °C; the calcination decomposition temperature in the calcination chamber (A2) is 800 - 1050 °C; In step 2), the temperature of the finished small particle CaO obtained after cooling is 80 - 100 °C; In step 3), the temperature of the high-temperature waste gas enriched at the top of the cooling chamber (A3) is 650 - 850 °C; the temperature of the waste gas discharged from the waste gas outlet on the preheating chamber (A1) is 100 - 130 °C; In step 4), the temperature of the high-temperature CO2 gas entering the calcination chamber air box (7) after heat supplementation is 1000 - 1100 °C.

20. The method according to claim 19, wherein: In step 1), the temperature of the preheated material is 650 - 750 °C; the calcination decomposition temperature in the calcination chamber (A2) is 900 - 1000 °C; In step 3), the temperature of the high-temperature waste gas enriched at the top of the cooling chamber (A3) is 700 - 800 °C.

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