Process for lime fractional oxygen enrichment calcination

Abstract

The application discloses a lime grading oxygen-enriched calcination process, which comprises the following steps: 1) putting limestone into a calcination chamber of a lime shaft kiln and flowing from top to bottom for calcination treatment, and discharging the calcined product from a discharge port at the bottom of the calcination chamber; and 2) calculating the required fuel quantity for the calcination treatment according to the input quantity of the limestone, and adding the required fuel from different height positions of the calcination chamber into the calcination chamber in a gradually increasing manner from top to bottom in the vertical direction for combustion to provide the required heat for the calcination treatment. The lime grading oxygen-enriched calcination process provided by the application divides the lime shaft kiln into multiple combustion sections, then adds fuel and combustion-supporting gas into the lime shaft kiln in sections, enriches CO2 at the exhaust port of the kiln bottom, significantly reduces the inhibiting effect of high-concentration CO2 on the decomposition of CaCO3, and has little influence on the production efficiency of the lime shaft kiln.

Description

Technical Field

[0001] This invention relates to an oxygen-enriched calcination process, specifically a graded oxygen-enriched calcination process for lime, belonging to the field of lime calcination technology. Background Technology

[0002] Quicklime is an important industrial raw material with wide applications in industries such as steel, calcium carbide, and alumina, and its demand is enormous. my country's lime production has increased continuously over the past decade, making it a key target for CO2 emission reduction and carbon capture in the industrial sector.

[0003] The CO2 concentration in the flue gas produced by conventional lime production processes is currently low, generally below 20%. Since the cost of carbon capture increases as the concentration of carbon dioxide in the capture source decreases, it can reach over 300 yuan / ton of carbon dioxide. As a result, most manufacturers directly discharge the exhaust gas into the atmosphere, causing a huge waste of resources and environmental pollution. Therefore, the excessively low CO2 concentration at the tail end greatly limits the large-scale application of carbon capture technology in lime kiln equipment.

[0004] To address the aforementioned issues, industry professionals have proposed a carbon front-end enrichment technology. This technology obtains high-concentration CO2 flue gas by reducing or eliminating other gaseous components in the flue gas, thereby significantly reducing the cost of carbon capture at the tail end and achieving near-zero emissions in lime production. The main technical feature of this method is the use of pure oxygen and circulating flue gas for calcination to obtain high-concentration CO2 flue gas, while simultaneously using circulating flue gas instead of cooling air to cool the high-temperature lime.

[0005] However, the circulating flue gas contains a high concentration of CO2, which, along with pure oxygen, enters the calcining chamber from the top, significantly inhibiting the decomposition reaction of limestone. This is because the main component of limestone is CaCO3, and its decomposition reaction equation is as follows:

[0006]

[0007] As shown in the above reaction equations, the decomposition of limestone produces CO2. Therefore, the concentration of CO2 inside the calcining chamber affects the forward direction of the limestone decomposition reaction. The relationship between the limestone decomposition reaction rate and the CO2 concentration is as follows: Figure 4 As shown in the figure, the limestone decomposition reaction rate has an exponential relationship with CO2 concentration and partial pressure.

[0008] The existing oxygen-enriched combustion and flue gas recirculation process for lime kilns uses a single method for feeding and introducing fuel and combustion-supporting gases. Basically, the fuel is fed in all at once, and the pure oxygen and flue gas are mixed before being introduced into the kiln or introduced into the kiln in sequence. This results in the entire furnace being filled with high concentrations of CO2 gas, which inhibits the decomposition of CaCO3 and significantly reduces the production efficiency of lime kilns. Summary of the Invention

[0009] To address the problems of excessively high carbon capture costs in existing technologies, and the single air intake method in the oxygen-enriched combustion and flue gas recirculation process of lime kilns, which inhibits CaCO3 decomposition and significantly reduces the production efficiency of lime kilns, this invention proposes a graded oxygen-enriched combustion process for lime kilns. This process divides the lime kiln into multiple combustion sections and introduces fuel and combustion-supporting gases in each section. While achieving CO2 enrichment, the CO2 concentration in the lime kiln gradually increases from top to bottom, eventually reaching the maximum concentration at the bottom of the lime kiln, without affecting the production efficiency of the lime kiln.

[0010] According to a first embodiment of the present invention, a lime grading oxygen-enriched calcination process is provided.

[0011] A graded oxygen-enriched calcination process for lime includes the following steps:

[0012] 1) Limestone is fed into the calcination chamber of the lime vertical kiln and calcined from top to bottom. The calcined product is discharged from the discharge port at the bottom of the calcination chamber.

[0013] 2) Calculate the amount of fuel required for calcination based on the amount of limestone added. In the vertical direction, the required fuel is added from different heights in the calcination chamber to provide the heat required for calcination by gradually increasing the amount added from top to bottom.

[0014] Preferably, the process also includes:

[0015] 3) Based on the calculated fuel burnout, the oxygen demand is estimated. In the vertical direction, oxygen-containing gas that meets the oxygen demand is added into the calcining chamber from the fuel addition position at the top of the calcining chamber. At the same time, low-oxygen gas is introduced into each of the fuel addition positions below as combustion air.

[0016] Preferably, step 2) involves calculating the amount of fuel required for calcination based on the amount of limestone input, specifically as follows:

[0017] Q f =m lime *C f *1000 / 24

[0018] In the formula, m lime The capacity of the lime kiln is t / d; C f Fuel quantity required to produce one unit of lime (kg / kg or Nm³) 3 / kg); Q f The unit is kg / h (or Nm³). 3 / h);

[0019] Step 3) involves calculating the oxygen requirement based on the calculated fuel burnout, specifically as follows:

[0020] Q y =Q f *C k

[0021] In the formula, C k The amount of oxygen required per unit of fuel, expressed in Nm³. 3 / kg (or Nm 3 / Nm 3 );Q y The unit is Nm 3 / h.

[0022] Preferably, step 2) involves adding the required fuel into the calcining chamber from different height positions within the calcining chamber: dividing the calcining chamber into n combustion sections from top to bottom, and adding fuel into the calcining chamber from each combustion section; wherein, n takes the value of 2 to 8, preferably 2 to 5.

[0023] Preferably, step 3) involves introducing circulating flue gas into each of the fuel addition positions below as follows: circulating flue gas is introduced into the calcining chamber from each combustion section of the fuel inlet position defined in step 2).

[0024] Preferably, the value of n is 3, and the lime vertical kiln is divided into 3 combustion zones, which are combustion zone I, combustion zone II and combustion zone III from top to bottom.

[0025] Preferably, in step 3), the oxygen-containing gas, which meets the oxygen demand, is added to the calcining chamber from the fuel addition position at the top of the calcining chamber in the vertical direction, while circulating flue gas is introduced as combustion air to each of the fuel addition positions below: high-oxygen-content gas is introduced into combustion zone I, and circulating flue gas is introduced into combustion zones II and III; preferably, the high-oxygen-content gas is oxygen; preferably, the total oxygen content Q in the high-oxygen-content gas is... y1 =0.98~1.1Q y The total oxygen content Q in the circulating flue gas y2 =0.01~0.1Q y .

[0026] Preferably, the method for confirming the specific height and fuel supply of combustion zones I, II, and III is as follows: First, fuel and oxygen-containing gas are introduced only into the top of the combustion chamber, and the temperature inside the chamber is detected. The temperature critical surface at which the temperature of a certain section inside the combustion chamber drops from above the set temperature to below the set temperature is obtained. This surface is the boundary between combustion zone I and combustion zone II. The fuel supply of combustion zone I is controlled according to the real-time temperature in combustion zone I. Then, fuel and circulating flue gas are introduced into combustion zones II and III in sequence. The boundary between combustion zones II and III is measured using the same method, and the fuel supply of combustion zones II and III is controlled.

[0027] Preferably, the temperature inside the detection chamber is obtained by detecting the real-time temperature inside the calcination chamber using a temperature detection device installed inside the lime vertical kiln.

[0028] Preferably, the calcining chamber is divided into N planes from top to bottom along the height direction, and the temperature of the N planes is detected. The value of N is 2 to 30, preferably 5 to 25.

[0029] Preferably, the temperature of each plane is obtained by detecting the temperature of M points within the plane and calculating it, wherein the value of M is 1 to 15, preferably 6 to 12.

[0030] Preferably, among the M points on the same plane, one is set at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

[0031] Preferably, the method for confirming the specific height and fuel quantity of the combustion zone I is as follows: Temperature detection devices are installed in N planes from top to bottom within the combustion zone I to obtain temperature data for each plane.

[0032] T1(t)=∑T 1,j (t) / (M+1)

[0033] T2(t)=∑T 2,j (t) / (M+1)

[0034] ...

[0035] T N (t)=∑T N,j (t) / (M+1)

[0036] Where j = 0, 1, 2…M; find T1(t), T2(t)……T N The highest temperature T in (t) a (t);

[0037] If T a(t)>Tc+25°C, reduce the fuel injection amount in the combustion zone I, and the fuel injection amount at the next moment is:

[0038] Q f1 (t+1)=Q f1 (t)+k f *(Tc-T a (t))*C p / ΔQ h ;

[0039] if T a (t)<Tc-25°C, increase the fuel injection amount in the combustion zone I, and the fuel injection amount at the next moment is:

[0040] Q f1 (t+1)=Q f1 (t)+k f *(Tc-T a (t))*C p / ΔQ h ;

[0041] wherein, Tc is the optimal temperature in the calcination process of a lime vertical kiln, with a value of 1050~1250°C, preferably 1100~1200°C; C p is specific heat of fuel, J / (kg·°C); ΔQ h is calorific value of fuel, J / kg; k f is an adjustment coefficient, with a value of 0.01 to 0.1; after multiple adjustments until T a (t) is within the range of Tc±25°C, the adjustment of the fuel amount introduced into combustion zone I is completed;

[0042] in addition, according to the temperature data in each plane, find the detection point p corresponding to p (t)<Tc-50°C, T p-1 (t)>Tc+50°C, and the middle position between the plane where point p is located and the plane where point p-1 is located is the boundary line between combustion zone I and combustion zone II.

[0043] preferably, the method for confirming the specific height of the combustion zone II and the fuel amount introduced therein is: controlling the fuel injection position of the combustion zone II to be the middle position between detection point p and detection point p-1, injecting secondary fuel here, and controlling the fuel injection amount as:

[0044] Q f2 =(Q f -Q f1 ) / 2

[0045] and injecting circulating flue gas at the same position, with the initial injection amount being:

[0046] Q g2 (t0)=Qf2 *Q air *k p

[0047] In the formula, Q air is the amount of combustion-supporting air required per unit fuel, and its specific value is determined according to the type of fuel used; preferably, for coal-fired kilns: Q air =10 to 11; for coke oven gas: Q air =5.5 to 6.5; for converter gas: Q air =1.5 to 1.7;

[0048] k p is the replacement ratio of unit circulating flue gas volume to unit air volume, which is equal to the sum of replacement ratios of each gas component and nitrogen, and the calculation formula is as follows:

[0049] wherein i is a gas component in the circulating flue gas, m is the number of gas components, ε i is the volume fraction of the i-th gas component, k i is the replacement ratio of the i-th gas component to nitrogen, with a value ranging from 0.8 to 1.2.

[0050] After combustion in combustion zone II is stabilized, at any time t, the average temperature of the plane where each detection point is located in the area below the boundary between combustion zone I and combustion zone II is obtained:

[0051] T p+1 (t)=∑T p+1,j (t) / (M+1)

[0052] T p+2 (t)=∑T p+2,j (t) / (M+1)

[0053] ……

[0054] T N (t)=∑T N,j (t) / (M+1)

[0055] wherein j=0,1,2……M; the maximum value T p+1 (t), T p+2 (t)……T N (t) is obtained as T b (t);

[0056] If T b (t)<Tc-25℃, reduce the feeding amount of circulating flue gas in combustion zone II, and the feeding amount of circulating flue gas at the next moment is:

[0057] Q g2 (t+1)=Q g2 (t)+kg *Q g2 (t)*(T b (t)-Tc) / Tc;

[0058] If T b (t)>Tc+25℃, increase the flow rate of circulating flue gas in combustion zone II. The flow rate of circulating flue gas at the next moment will be:

[0059] Q g2 (t+1)=Q g2 (t)+k g *Q g2 (t)*(T b (t)-Tc) / Tc;

[0060] In the formula, k g This is the adjustment coefficient, with a value ranging from 0.1 to 1; it is adjusted multiple times until T is reached. b (t) Within the range of Tc±25℃, the adjustment of combustion zone II is completed.

[0061] In addition, based on the temperature data in each plane, find T q (t) <Tc-50℃,T q-1 The detection point q corresponding to (t)>Tc-50℃, the midpoint between the q plane and the q-1 plane is the boundary line between combustion zone II and combustion zone III.

[0062] Preferably, the specific height of the combustion zone III is the distance from the midpoint between plane q and plane q-1 to the bottom of the combustion chamber; the method for confirming the amount of fuel introduced into the combustion zone III is as follows: the fuel injection position in the combustion zone III is controlled to be the midpoint between detection points q and q-1, and the third-stage fuel is injected at this point, while controlling the fuel injection amount:

[0063] Q f3 =Q f -Q f1 -Q f2

[0064] And inject recirculated flue gas at the same location, with an initial injection volume of:

[0065] Q g3 (t0)=Q f3 *Q air *k p

[0066] In the formula, Q air k is the amount of combustion-supporting gas required per unit of fuel. p The replacement ratio of a unit volume of circulating flue gas to a unit volume of air;

[0067] After combustion in the III zone is stabilized, obtain the average temperature of the plane where each detection point is located in the area below the boundary between the combustion II zone and the combustion III zone at any time t:

[0068] T q+1 (t)=∑T q+1,j (t) / (M+1)

[0069] T q+2 (t)=∑T q+2,j (t) / (M+1)

[0070] ……

[0071] T N (t)=∑T N,j (t) / (M+1)

[0072] wherein j=0,1,2……M; obtain the maximum temperature T q+1 (t), T q+2 (t)……T N (t) as T d (t);

[0073] if T d (t)<Tc-25°C, reduce the fuel feed amount in the combustion III zone, and the fuel feed amount at the next moment is:

[0074] Q g3 (t+1)=Q g3 (t)+k g *Q g3 (t)*(T d (t)-Tc) / Tc;

[0075] if T d (t)>Tc+25°C, increase the circulating flue gas feed amount in the combustion III zone, and the circulating flue gas feed amount at the next moment is:

[0076] Q g3 (t+1)=Q g3 (t)+k g *Q g3 (t)*(T d (t)-Tc) / Tc;

[0077] in the formula, k g is an adjustment coefficient, with a value range of 0.1 to 1; after multiple adjustments until T d (t) is within the range of Tc±25°C, the adjustment of the combustion III zone is completed.

[0078] Preferably, step 2) involves adding the required fuel into the calcining chamber from different height positions within the chamber as follows: the amount of fuel introduced into combustion zone I is 15-45% of the total fuel amount, the amount of fuel introduced into combustion zone II is 15-45% of the total fuel amount, and the amount of fuel introduced into combustion zone III is 25-55% of the total fuel amount; preferably, the amount of fuel introduced into combustion zone I is 25-35% of the total fuel amount, the amount of fuel introduced into combustion zone II is 25-35% of the total fuel amount, and the amount of fuel introduced into combustion zone III is 35-45% of the total fuel amount; preferably, the fuel is pulverized coal.

[0079] Preferably, the height of combustion zone I is 10-25% of the height of the lime vertical kiln, the height of combustion zone II is 25-45% of the height of the lime vertical kiln, and the height of combustion zone III is 40-60% of the height of the lime vertical kiln; more preferably, the height of combustion zone I is 12-20% of the height of the lime vertical kiln, the height of combustion zone II is 30-40% of the height of the lime vertical kiln, and the height of combustion zone III is 45-55% of the height of the lime vertical kiln.

[0080] According to a second embodiment of the present invention, a lime graded oxygen-enriched calcination system is provided.

[0081] A graded oxygen-enriched calcination system for lime includes a calcination chamber, a fuel delivery pipeline, and a combustion-supporting gas delivery pipeline. The calcination chamber is divided into n combustion zones from top to bottom, each independently connected to both the fuel delivery pipeline and the combustion-supporting gas delivery pipeline. The fuel delivery pipeline 2 is connected to a fuel source 7. The uppermost combustion zone is connected to an oxygen-containing gas source via the combustion-supporting gas delivery pipeline, while the other combustion zones are connected to a low-oxygen gas source via the same pipeline. The value of n is 2–8, preferably 2–5.

[0082] Preferably, valves are installed inside the fuel delivery pipeline and the combustion-supporting gas delivery pipeline.

[0083] Preferably, the calcination chamber is divided into three combustion zones from top to bottom: Combustion Zone I, Combustion Zone II, and Combustion Zone III. Preferably, the height of Combustion Zone I is 10-25% of the height of the lime vertical kiln, the height of Combustion Zone II is 25-45% of the height of the lime vertical kiln, and the height of Combustion Zone III is 40-60% of the height of the lime vertical kiln. Preferably, the height of Combustion Zone I is 12-20% of the height of the lime vertical kiln, the height of Combustion Zone II is 30-40% of the height of the lime vertical kiln, and the height of Combustion Zone III is 45-55% of the height of the lime vertical kiln.

[0084] Preferably, the calcining chamber is equipped with a temperature detection device.

[0085] Preferably, the calcining chamber is divided into N planes from top to bottom along the height direction, and each of the N planes is equipped with a temperature detection device. The value of N is 2 to 30, preferably 5 to 25.

[0086] Preferably, each plane is provided with M temperature detection devices, where M is 1 to 15, and preferably 6 to 12.

[0087] Preferably, among the M points on the same plane, one is set at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

[0088] In this invention, limestone is calcined from top to bottom within the calcining chamber. Fuel is added to the calcining chamber in stages, with the amount gradually increasing from top to bottom. Preferably, oxygen-containing gas sufficient to meet the oxygen demand is introduced at the fuel addition position at the top of the calcining chamber. Since the amount of fuel added at the top of the calcining chamber is limited, the resulting CO2 concentration is low. Therefore, the CO2 concentration gradually increases from top to bottom within the calcining chamber. Under the premise of constant total oxygen content and ensuring complete fuel combustion, the CO2 concentration in the upper part of the calcining chamber can be effectively reduced. This reduction in CO2 concentration at the top of the lime kiln significantly reduces the inhibitory effect of high-concentration CO2 on CaCO3 decomposition, allowing CaCO3 to decompose fully in the upper combustion section, thus having a smaller impact on the production efficiency of the lime kiln. Simultaneously, introducing circulating flue gas to fuel addition positions other than the top one achieves the goal of enriching CO2 at the bottom of the calcining chamber, reducing the cost of carbon capture, expanding the scale of carbon capture technology application, and achieving the goal of CO2 emission reduction.

[0089] In this invention, the required fuel and oxygen quantities are calculated based on the amount of limestone input, enabling quantitative control of fuel and oxygen-containing gas within the calcining chamber. Preferably, the calcining chamber is divided into 2 to 8 combustion sections according to the actual production conditions, with fuel introduced in stages to improve lime production efficiency and reduce the occurrence of reverse reactions.

[0090] In this invention, the lime vertical kiln is further divided into three combustion zones, with fuel and combustion air introduced in stages. Preferably, the fuel injection rate (or circulating flue gas injection rate) and the position of each combustion zone are controlled by detecting the temperature inside the calcination chamber. More preferably, the temperature of x planes in the calcination chamber is detected from top to bottom. After obtaining the temperature data for each plane, the amount of fuel injected into combustion zone I is controlled based on the highest temperature obtained, ensuring that the temperature in combustion zone I meets the temperature requirements for lime calcination. Furthermore, based on the temperature data for each plane, the interface between combustion zone I and combustion zone II can be determined (i.e., the temperature above the interface meets the temperature requirements for lime calcination, while the temperature below the interface does not). Similarly, the interface between combustion zone II and combustion zone III, as well as the circulating flue gas injection rates in combustion zones II and III, can be determined. This achieves precise temperature control within the calcination chamber, resulting in CO2 enrichment and improving the calcination efficiency and product quality stability of the lime.

[0091] In this invention, by detecting the temperature at M points in each plane and calculating the average temperature of each plane, and preferably detecting the temperature at the center and around the perimeter of the plane, the amount and location of fuel introduced into the calcination chamber can be controlled more precisely, thereby improving calcination efficiency and product quality.

[0092] In this invention, after temperature adjustment, a CO2 concentration monitoring device can be installed inside the lime vertical kiln. The detection frequency for CO2 concentration inside the lime vertical kiln is 1-3 minutes. The CO2 volume fraction in combustion zone I is 15-25%. The CO2 volume fraction in combustion zone II is 55-70%. The CO2 volume fraction in combustion zone III is 70-99%. This ensures the normal decomposition of CaCO3, reduces the occurrence of reverse reactions, and achieves the best CO2 enrichment effect.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] 1. The present invention provides a graded oxygen-enriched calcination process for lime, which divides the lime vertical kiln into multiple combustion sections, and then introduces fuel and combustion-supporting gas into the lime vertical kiln in sections. While enriching CO2 at the exhaust port at the bottom of the kiln, it significantly reduces the inhibitory effect of high concentration CO2 on the decomposition of CaCO3, and has little impact on the production efficiency of the lime vertical kiln.

[0095] 2. The present invention provides a graded oxygen-enriched calcination process for lime, which monitors the temperature of a vertical lime kiln that is fed with fuel and combustion-supporting gas in stages, and adjusts the amount of fuel and / or combustion-supporting gas in each combustion stage to achieve uniform combustion, improve the stability of output, promote uniform heating of materials in the kiln, and avoid excessively rapid heating of the material surface. Attached Figure Description

[0096] Figure 1 This is a schematic diagram of a lime grading oxygen-enriched calcination system provided by the present invention.

[0097] Figure 2 This is a schematic diagram showing the vertical distribution of temperature detection devices in a lime grading oxygen-enriched calcination system provided by the present invention.

[0098] Figure 3 This is a schematic diagram showing the horizontal distribution of temperature detection devices in a lime grading oxygen-enriched calcination system provided by the present invention.

[0099] Figure 4 The graph shows the relationship between the limestone decomposition reaction rate and the CO2 concentration.

[0100] Reference numerals: 1: Calcination chamber; 11: Combustion zone I; 12: Combustion zone II; 13: Combustion zone III; 2: Fuel delivery pipeline; 3: Combustion-supporting gas delivery pipeline; 4: Oxygen-containing gas source; 5: Low-oxygen gas source; 6: Temperature detection device; 7: Fuel source. Detailed Implementation

[0101] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0102] According to a first embodiment of the present invention, a lime grading oxygen-enriched calcination process is provided.

[0103] A graded oxygen-enriched calcination process for lime includes the following steps:

[0104] 1) Limestone is fed into the calcination chamber of the lime vertical kiln and calcined from top to bottom. The calcined product is discharged from the discharge port at the bottom of the calcination chamber.

[0105] 2) Calculate the amount of fuel required for calcination based on the amount of limestone added. In the vertical direction, the required fuel is added from different heights in the calcination chamber to provide the heat required for calcination by gradually increasing the amount added from top to bottom.

[0106] As a preferred embodiment, the process also includes:

[0107] 3) Based on the calculated fuel burnout, the oxygen demand is estimated. In the vertical direction, oxygen-containing gas that meets the oxygen demand is added into the calcining chamber from the fuel addition position at the top of the calcining chamber. At the same time, low-oxygen gas is introduced into each of the fuel addition positions below as combustion air.

[0108] Preferably, step 2) involves calculating the amount of fuel required for calcination based on the amount of limestone input, specifically as follows:

[0109] Q f =m lime *C f *1000 / 24

[0110] In the formula, m lime The capacity of the lime kiln is t / d; C f Fuel quantity required to produce one unit of lime (kg / kg or Nm³) 3 / kg); Q f The unit is kg / h (or Nm³). 3 / h);

[0111] Step 3) involves calculating the oxygen requirement based on the calculated fuel burnout, specifically as follows:

[0112] Q y =Q f *C k

[0113] In the formula, C k The amount of oxygen required per unit of fuel, expressed in Nm³. 3 / kg (or Nm 3 / Nm 3 );Q y The unit is Nm 3 / h.

[0114] Preferably, step 2) involves adding the required fuel into the calcining chamber from different height positions within the calcining chamber as follows: the calcining chamber is divided into n combustion sections from top to bottom, and fuel is added into the calcining chamber from each combustion section; wherein, n takes the value of 2 to 8, preferably 2 to 5.

[0115] Preferably, step 3) involves introducing circulating flue gas into each of the fuel addition positions below: circulating flue gas is introduced into the calcining chamber from each combustion section of the fuel inlet position defined in step 2).

[0116] Preferably, the value of n is 3, and the lime vertical kiln is divided into 3 combustion zones, which are combustion zone I, combustion zone II and combustion zone III from top to bottom.

[0117] Preferably, in step 3), the oxygen-containing gas meeting the oxygen demand is added to the calcining chamber from the fuel addition position at the top of the calcining chamber in the vertical direction, while circulating flue gas is introduced as combustion air to each of the fuel addition positions below: high-oxygen-content gas is introduced into combustion zone I, and circulating flue gas is introduced into combustion zones II and III; preferably, the high-oxygen-content gas is oxygen; preferably, the total oxygen content Q in the high-oxygen-content gas is... y1 =0.98~1.1Qy The total oxygen content Q in the circulating flue gas y2 =0.01~0.1Q y .

[0118] Preferably, the method for confirming the specific height and fuel supply of combustion zones I, II, and III is as follows: First, fuel and oxygen-containing gas are introduced only into the top of the combustion chamber, and the temperature inside the chamber is detected. The temperature critical surface at which the temperature of a certain section inside the combustion chamber drops from above the set temperature to below the set temperature is obtained. This surface is the boundary between combustion zone I and combustion zone II. The fuel supply of combustion zone I is controlled according to the real-time temperature in combustion zone I. Then, fuel and circulating flue gas are introduced into combustion zones II and III in sequence. The boundary between combustion zones II and III is measured using the same method, and the fuel supply of combustion zones II and III is controlled.

[0119] Preferably, the temperature inside the detection chamber is obtained by detecting the real-time temperature inside the calcination chamber using a temperature detection device installed inside the lime vertical kiln.

[0120] Preferably, the calcining chamber is divided into N planes from top to bottom along the height direction, and the temperature of the N planes is detected. The value of N is 2 to 30, preferably 5 to 25.

[0121] Preferably, the temperature of each plane is obtained by detecting the temperature of M points within the plane and calculating it, wherein the value of M is 1 to 15, preferably 6 to 12.

[0122] Preferably, among the M points on the same plane, one is set at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

[0123] Preferably, the method for confirming the specific height and fuel quantity of the combustion zone I is as follows: Temperature detection devices are installed in N planes from top to bottom within the combustion zone I to obtain temperature data for each plane.

[0124] T1(t)=∑T 1,j (t) / (M+1)

[0125] T2(t)=∑T 2,j (t) / (M+1)

[0126] ...

[0127] T N (t)=∑T N,j (t) / (M+1)

[0128] Where j = 0, 1, 2…M; find T1(t), T2(t)……T Nthe maximum value T of temperature in (t) a (t);

[0129] if T a (t)>Tc+25°C, reduce the fuel injection amount in combustion zone I, and the fuel injection amount at the next moment is:

[0130] Q f1 (t+1)=Q f1 (t)+k f *(Tc-T a (t))*C p / ΔQ h ;

[0131] if T a (t)<Tc-25°C, increase the fuel injection amount in combustion zone I, and the fuel injection amount at the next moment is:

[0132] Q f1 (t+1)=Q f1 (t)+k f *(Tc-T a (t))*C p / ΔQ h ;

[0133] wherein, Tc is the optimal temperature in the calcination process of a lime shaft kiln, with a value of 1050 to 1250°C, preferably 1100 to 1200°C; C p is the specific heat of fuel, J / (kg·°C); ΔQ h is the calorific value of fuel, J / kg; k f is an adjustment coefficient, with a value of 0.01 to 0.1; after multiple adjustments until T a (t) is within the range of Tc±25°C, the adjustment of the fuel amount fed into combustion zone I is completed;

[0134] in addition, according to the temperature data in each plane, find T p (t)<Tc-50°C and T p-1 (t)>Tc-50°C corresponding detection point p, the middle position between the plane where point p is located and the plane where point p-1 is located is the boundary between combustion zone I and combustion zone II.

[0135] preferably, the method for confirming the specific height of combustion zone II and the injected fuel amount is: controlling the fuel injection position of combustion zone II to be the middle position between detection point p and detection point p-1, injecting secondary fuel here, and controlling the fuel injection amount:

[0136] Q f2 =(Q f -Q f1 ) / 2

[0137] And inject recirculated flue gas at the same location, with an initial injection volume of:

[0138] Q g2 (t0)=Q f2 *Q air *k p

[0139] In the formula, Q air Q is the amount of combustion air required per unit of fuel, the specific value of which is determined according to the type of fuel used; preferably, for coal-fired kilns: Q air =10~11; Coke oven gas: Q air =5.5~6.5; Converter gas: Q air =1.5~1.7;

[0140] k p The replacement ratio of a unit volume of circulating flue gas to a unit volume of air is equal to the sum of the replacement ratios of each gas component to nitrogen. The calculation formula is as follows:

[0141] Where i is the gas component in the circulating flue gas, m is the number of gas components, and ε i Let k be the volume fraction of the i-th gas component. i The replacement ratio of the i-th gas component with nitrogen is given, and its value ranges from 0.8 to 1.2.

[0142] After combustion stabilizes in combustion zone II, the average temperature of the plane containing each detection point in the region below the boundary between combustion zone I and combustion zone II at any time t is obtained:

[0143] T p+1 (t)=∑T p+1,j (t) / (M+1)

[0144] T p+2 (t)=∑T p+2,j (t) / (M+1)

[0145] ...

[0146] T N (t)=∑T N,j (t) / (M+1)

[0147] Where j = 0, 1, 2, ..., M; we obtain T p+1 (t), T p+2 (t)……T N The highest temperature T in (t) b (t);

[0148] If T b(t)<Tc-25°C, reduce the feed flow rate of circulating flue gas in combustion zone II, and the feed flow rate of circulating flue gas at the next moment is:

[0149] Q g2 (t+1)=Q g2 (t)+k g *Q g2 (t)*(T b (t)-Tc) / Tc;

[0150] If T b (t)>Tc+25°C, increase the feed flow rate of circulating flue gas in combustion zone II, and the feed flow rate of circulating flue gas at the next moment is:

[0151] Q g2 (t+1)=Q g2 (t)+k g *Q g2 (t)*(T b (t)-Tc) / Tc;

[0152] wherein, k g is an adjustment coefficient, with a value ranging from 0.1 to 1; after multiple adjustments until T b (t) is within the range of Tc±25°C, the adjustment of combustion zone II is completed.

[0153] In addition, based on the temperature data in each plane, find the detection point q corresponding to T q (t)<Tc-50°C and T q-1 (t)>Tc-50°C, and the middle position between plane q and plane q-1 is the boundary line between combustion zone II and combustion zone III.

[0154] Preferably, the specific height of said combustion zone III is the distance from the middle position between plane q and plane q-1 to the bottom of the calcining chamber; the method for determining the feed amount of fuel into combustion zone III is as follows: controlling the fuel injection position of combustion zone III to be the middle position between detection points q and q-1, injecting tertiary fuel herein, and controlling the fuel injection amount as:

[0155] Q f3 =Q f -Q f1 -Q f2

[0156] and injecting circulating flue gas at the same position, the initial injection amount is:

[0157] Q g3 (t0)=Q f3 *Q air *k p

[0158] wherein, Qair is the amount of combustion-supporting gas required per unit fuel, k p is the replacement ratio of unit circulating flue gas volume to unit air volume;

[0159] after combustion in the combustion zone III is stabilized, obtain the average temperature of the plane where each detection point is located in the area below the boundary between the combustion zone II and the combustion zone III at any time t:

[0160] T q+1 (t)=∑T q+1,j (t) / (M+1)

[0161] T q+2 (t)=∑T q+2,j (t) / (M+1)

[0162] ……

[0163] T N (t)=∑T N,j (t) / (M+1)

[0164] wherein, j=0,1,2……M;obtain the maximum temperature value T q+1 (t), T q+2 (t)……T N (t), which is denoted as T d (t);

[0165] if T d (t)<Tc-25℃, reduce the feeding amount of circulating flue gas in combustion zone III, and the feeding amount of circulating flue gas at the next moment is:

[0166] Q g3 (t+1)=Q g3 (t)+k g *Q g3 (t)*(T d (t)-Tc) / Tc;

[0167] if T d (t)>Tc+25℃, increase the feeding amount of circulating flue gas in combustion zone III, and the feeding amount of circulating flue gas at the next moment is:

[0168] Q g3 (t+1)=Q g3 (t)+k g *Q g3 (t)*(T d (t)-Tc) / Tc;

[0169] in the formula, k g is an adjustment coefficient with a value ranging from 0.1 to 1; after multiple adjustments until T d(t) Within the range of Tc±25℃, the adjustment of combustion zone III is completed.

[0170] Preferably, step 2) involves adding the required fuel into the calcining chamber from different height positions within the chamber as follows: the amount of fuel introduced into combustion zone I is 15-45% of the total fuel amount, the amount of fuel introduced into combustion zone II is 15-45% of the total fuel amount, and the amount of fuel introduced into combustion zone III is 25-55% of the total fuel amount; preferably, the amount of fuel introduced into combustion zone I is 25-35% of the total fuel amount, the amount of fuel introduced into combustion zone II is 25-35% of the total fuel amount, and the amount of fuel introduced into combustion zone III is 35-45% of the total fuel amount; preferably, the fuel is pulverized coal.

[0171] Preferably, the height of combustion zone I is 10-25% of the height of the lime vertical kiln, the height of combustion zone II is 25-45% of the height of the lime vertical kiln, and the height of combustion zone III is 40-60% of the height of the lime vertical kiln; more preferably, the height of combustion zone I is 12-20% of the height of the lime vertical kiln, the height of combustion zone II is 30-40% of the height of the lime vertical kiln, and the height of combustion zone III is 45-55% of the height of the lime vertical kiln.

[0172] According to a second embodiment of the present invention, a lime graded oxygen-enriched calcination system is provided.

[0173] A graded oxygen-enriched calcination system for lime includes a calcination chamber 1, a fuel delivery pipeline 2, and a combustion-supporting gas delivery pipeline 3. The calcination chamber 1 is divided into n combustion zones from top to bottom, each combustion zone being independently connected to both the fuel delivery pipeline 2 and the combustion-supporting gas delivery pipeline 3. The fuel delivery pipeline 2 is connected to a fuel source 7. The uppermost combustion zone is connected to an oxygen-containing gas source 4 via the combustion-supporting gas delivery pipeline 3, while the other combustion zones are connected to a low-oxygen gas source 5 via the combustion-supporting gas delivery pipeline 3. The value of n is 2 to 8, preferably 2 to 5.

[0174] Preferably, valves are installed inside the fuel delivery pipeline 2 and the combustion-supporting gas delivery pipeline 3.

[0175] Preferably, the calcining chamber 1 is divided into three combustion zones from top to bottom: combustion zone I 11, combustion zone II 12, and combustion zone III 13. Preferably, the height of combustion zone I 11 is 10-25% of the height of the lime vertical kiln, the height of combustion zone II 12 is 25-45% of the height of the lime vertical kiln, and the height of combustion zone III 13 is 40-60% of the height of the lime vertical kiln. Preferably, the height of combustion zone I 11 is 12-20% of the height of the lime vertical kiln, the height of combustion zone II 12 is 30-40% of the height of the lime vertical kiln, and the height of combustion zone III 13 is 45-55% of the height of the lime vertical kiln.

[0176] Preferably, the calcining chamber 1 is equipped with a temperature detection device 6.

[0177] Preferably, the calcining chamber is divided into N planes from top to bottom along the height direction, and each of the N planes is equipped with a temperature detection device 6, where N is 2 to 30, preferably 5 to 25.

[0178] Preferably, each plane is provided with M temperature detection devices 6, where M is 1 to 15, and preferably 6 to 12.

[0179] Preferably, among the M points on the same plane, one is set at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

[0180] Example 1

[0181] A graded oxygen-enriched calcination system for lime includes a calcination chamber 1, a fuel delivery pipeline 2, and a combustion-supporting gas delivery pipeline 3. The calcination chamber 1 is divided into three combustion zones from top to bottom: combustion zone I, combustion zone II, and combustion zone III. Each combustion zone is independently connected to both the fuel delivery pipeline 2 and the combustion-supporting gas delivery pipeline 3. The fuel delivery pipeline 2 is connected to a fuel source 7. The uppermost combustion zone is connected to an oxygen-containing gas source 4 via the combustion-supporting gas delivery pipeline 3, while the other combustion zones are connected to a low-oxygen gas source 5 via the combustion-supporting gas delivery pipeline 3.

[0182] Example 2

[0183] The same as Example 1 is repeated, except that valves are installed inside the fuel delivery pipeline 2 and the combustion-supporting gas delivery pipeline 3.

[0184] Example 3

[0185] Example 2 is repeated, except that the height of combustion zone I 11 is 15% of the height of the lime vertical kiln, the height of combustion zone II 12 is 35% of the height of the lime vertical kiln, and the height of combustion zone III 13 is 50% of the height of the lime vertical kiln.

[0186] Example 4

[0187] The same method as Example 3 is used, except that the calcining chamber 1 is equipped with a temperature detection device 6.

[0188] Example 5

[0189] Repeat Example 4, except that the calcining chamber is divided into 15 planes from top to bottom along the height direction, and each of the 15 planes is equipped with a temperature detection device 6.

[0190] Example 6

[0191] Repeat Example 5, except that each plane is equipped with 9 temperature detection devices 6.

[0192] Example 7

[0193] Repeat Example 6, except that of the nine points on the same plane, one is set at the center of the plane, and the other temperature detection devices are arranged in a circle around the center wall of the plane.

[0194] Application Examples

[0195] A graded oxygen-enriched calcination process for lime includes the following steps:

[0196] 1) Limestone is fed into the calcination chamber of the lime vertical kiln and calcined from top to bottom. The calcined product is discharged from the discharge port at the bottom of the calcination chamber.

[0197] 2) Calculate the amount of fuel required for calcination based on the amount of limestone input:

[0198]

[0199] In the formula, m lime The capacity of the lime kiln is taken as 500 t / d; C f The amount of fuel required to produce one unit of lime is taken as 0.13 kg / kg (fuel is pulverized coal).

[0200] In the vertical direction, the calcination chamber is divided into three combustion sections from top to bottom: combustion zone I, combustion zone II, and combustion zone III. Fuel is added into the calcination chamber from each combustion zone to provide the heat required for the calcination process.

[0201] 3) The oxygen requirement is calculated based on the calculated fuel burnout.

[0202] Q y =Q f *C k = 4604 Nm3 / h

[0203] In the formula, C k The amount of oxygen required per unit of fuel is taken as 1.7 Nm³. 3 / kg.

[0204] In the vertical direction, oxygen is introduced into combustion zone I, and recirculated flue gas is introduced into combustion zones II and III as combustion-supporting air. The oxygen injection rate Q... y1 =0.99Q y The total oxygen content Q in the circulating flue gas y2 =0.01Q y .

[0205] First, only 30% Q is introduced into combustion zone I.f The amount of fuel and all oxygen are measured, and the combustion chamber is divided into 15 surfaces from top to bottom, with 9 temperature detection points set in each surface (e.g., ...). Figure 3 (As shown). Temperature data were obtained in each plane:

[0206] T 1,0 (t) = 1140℃, T 1,1 (t) = 1151℃, T 1,2 (t) = 1142℃, T 1,3 (t) = 1143℃, T 1,4 (t) = 1146℃, T 1,5 (t) = 1145℃, T 1,6 (t) = 1143℃, T 1,7 (t) = 1147℃, T 1,8 (t) = 1148℃, therefore:

[0207]

[0208] Similarly, the calculated values ​​are T2(t) = 1139℃, T3(t) = 1132℃, T4(t) = 1125℃, and T5(t) = 1097℃. Since Tc is 1150℃, the height range of fuel zone I is between the top of the combustion chamber and the fourth and fifth planes. Furthermore, the highest temperature value T1(t) in combustion zone I is within the range of Tc ± 25℃. Therefore, the amount of fuel supplied to combustion zone I does not need to be adjusted.

[0209] Secondly, fuel and recirculated flue gas are introduced into combustion zone II, with the fuel injection rate being:

[0210]

[0211] And inject recirculated flue gas at the same location, with an initial injection volume of:

[0212] Q g2 (t0)=Q f2 *Q air *k p =13554Nm 3 / h

[0213] In the formula, Q air =10, Where i is the gas component in the circulating flue gas, m is the number of gas components, the circulating flue gas includes CO2, N2, H2O, and O2, and the value of m is 4, ε i Let k be the volume fraction of the i-th gas component. The volume fractions of CO2, N2, H2O, and O2 in the circulating flue gas are 82.4%, 8.3%, 6.8%, and 2.5%, respectively. iLet be the replacement ratio of the i-th gas component with nitrogen. The replacement ratios for CO2, H2O, and O2 are 1.509, 1.170, and 0.986, respectively. The calculated k... p =1.43;

[0214] After combustion stabilizes in combustion zone II, the average temperatures of the planes containing the detection points in and below the fifth plane at any given time t are obtained: T5(t) = 1182℃, T6(t) = 1194℃, T7(t) = 1179℃, T8(t) = 1168℃, T9(t) = 1142℃, T 10 (t) = 1125℃, T 11 (t) = 1097℃, the highest temperature in fuel zone II is T6(t) = 1194℃, adjust the amount of circulating flue gas introduced into combustion zone II:

[0215]

[0216] In the formula, k g The value is 0.52. After adjustment, the highest temperature in combustion zone II at time t+1 is T6(t+1) = 1173℃, completing the adjustment of combustion zone II. After the adjustment of fuel zone II is completed, T5(t+1) = 1170℃, T6(t+1) = 1173℃, T7(t+1) = 1161℃, T8(t+1) = 1158℃, T9(t+1) = 1136℃, T 10 (t+1)=1112℃, T 11 If (t+1) = 1085℃, then the height range of fuel zone II is between the 4th and 5th planes and between the 10th and 11th planes.

[0217] Finally, fuel and recirculated flue gas are introduced into combustion zone III, with the fuel injection rate being:

[0218] Q f3 =Q f -Q f1 -Q f2 =35%Q f

[0219] And inject recirculated flue gas at the same location, with an initial injection volume of:

[0220] Q g3 (t0)=Q f3 *Q air *k p =13554Nm 3 / h

[0221] In the formula, Q air =10,k p =1.43;

[0222] After combustion stabilizes in combustion zone III, the average temperature of the plane containing each detection point in the 11th plane and the area below the 11th plane is obtained at any time t: T 11 (t) = 1152℃, T 12 (t) = 1148℃, T 13 (t) = 1142℃, T 14 (t) = 1137℃, T 15 (t) = 1132℃, the height range of fuel zone III is from the 10th and 11th planes to the bottom of the combustion chamber, and the highest temperature T in combustion zone III is... 11 (t) Within the range of Tc±25℃, the amount of circulating flue gas introduced into combustion zone III does not need to be adjusted.

[0223] The CO2 concentration inside the lime vertical kiln was measured. The volume fractions of CO2 at 15 planes from top to bottom were: 15.1%, 19.3%, 22.5%, 24.8%, 57.0%, 61.1%, 64.3%, 66.0%, 67.6%, 68.9%, 78.2%, 83.7%, 86.9%, 89.8%, and 92.1%.

Claims

1. A graded oxygen-enriched calcination process for lime, characterized in that: The process includes the following steps: 1) Limestone is fed into the calcination chamber of the lime vertical kiln and calcined from top to bottom. The calcined product is discharged from the discharge port at the bottom of the calcination chamber. 2) Calculate the amount of fuel required for calcination based on the amount of limestone added. In the vertical direction, the required fuel is added from different heights in the calcination chamber to provide the heat required for calcination by gradually increasing the amount added from top to bottom. 3) Based on the calculated fuel burnout, the oxygen demand is estimated. In the vertical direction, oxygen-containing gas that meets the oxygen demand is added into the calcining chamber from the fuel addition position at the top of the calcining chamber. At the same time, low-oxygen-content gas is introduced into each of the fuel addition positions below as combustion air.

2. The process according to claim 1, characterized in that: Step 2) involves calculating the required fuel quantity for calcination based on the amount of limestone input. ； In the formula, The capacity of the lime kiln is t / d; C f Fuel quantity required to produce one unit of lime (kg / kg); Q f The unit is kg / h; Step 3) involves calculating the oxygen requirement based on the calculated fuel burnout, specifically as follows: ； In the formula, C k The amount of oxygen required per unit of fuel, expressed in Nm³. 3 / kg; Q y The unit is Nm 3 / h.

3. The process according to claim 1, characterized in that: Step 2) involves adding the required fuel into the calcining chamber from different height positions within the chamber: the calcining chamber is divided into n combustion sections from top to bottom, and fuel is added into the calcining chamber from each combustion section; where n ranges from 2 to 8.

4. The process according to claim 3, characterized in that: The value of n is between 2 and 5.

5. The process according to claim 3, characterized in that: Step 3) refers to introducing circulating flue gas into each of the fuel addition positions below: circulating flue gas is introduced into the calcining chamber from each combustion section of the fuel introduction positions divided in Step 2).

6. The process according to claim 5, characterized in that: The value of n is 3. The lime vertical kiln is divided into 3 combustion zones, which are combustion zone I, combustion zone II and combustion zone III from top to bottom.

7. The process according to claim 6, characterized in that: Step 3) In the vertical direction, oxygen-containing gas that meets the oxygen demand is added into the calcining chamber from the fuel addition position at the top of the calcining chamber. At the same time, circulating flue gas is introduced into each of the fuel addition positions below as combustion air: high oxygen content gas is introduced into combustion zone I, and circulating flue gas is introduced into combustion zone II and combustion zone III.

8. The process according to claim 7, characterized in that: The gas with high oxygen content is oxygen.

9. The process according to claim 7, characterized in that: Total oxygen content in high oxygen content gas Total oxygen content in circulating flue gas .

10. The process according to claim 7, characterized in that: The method for confirming the specific height and fuel supply of combustion zones I, II, and III is as follows: First, fuel and oxygen-containing gas are introduced only into the top of the combustion chamber, and the temperature inside the chamber is measured. The temperature critical surface where the temperature of a certain section inside the combustion chamber drops from above the set temperature to below the set temperature is obtained. This surface is the boundary between combustion zone I and combustion zone II. The fuel supply to combustion zone I is controlled based on the real-time temperature in combustion zone I. Then, fuel and circulating flue gas are introduced into combustion zones II and III sequentially. The boundary between combustion zones II and III is measured using the same method, and the fuel supply to combustion zones II and III is controlled accordingly; and / or The fuel is either gaseous or solid.

11. The process according to claim 10, characterized in that: The fuel is coal or CO.

12. The process according to claim 10, characterized in that: The fuel is pulverized coal.

13. The process according to claim 10, characterized in that: The temperature inside the chamber is detected by a temperature detection device installed inside the lime vertical kiln, which measures the real-time temperature inside the calcination chamber.

14. The process according to claim 13, characterized in that: Inside the calcining chamber, the chamber is divided into N planes from top to bottom along the height direction, and the temperature of the N planes is measured. The value of N is 2~30.

15. The process according to claim 14, characterized in that: The value of N ranges from 5 to 25.

16. The process according to claim 13, characterized in that: The temperature of each plane is obtained by detecting the temperature of M points within that plane and performing calculations, where M ranges from 1 to 15.

17. The process according to claim 16, characterized in that: The value of M is 6 to 12.

18. The process according to claim 16, characterized in that: Of the M points on the same plane, one is located at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

19. The process according to claim 6, characterized in that: Step 2) refers to adding the required fuel into the calcining chamber from different height positions: the amount of fuel introduced into combustion zone I is 15-45% of the total fuel amount, the amount of fuel introduced into combustion zone II is 15-45% of the total fuel amount, and the amount of fuel introduced into combustion zone III is 25-55% of the total fuel amount.

20. The process according to claim 19, characterized in that: The amount of fuel introduced into combustion zone I is 25-35% of the total fuel, the amount of fuel introduced into combustion zone II is 25-35% of the total fuel, and the amount of fuel introduced into combustion zone III is 35-45% of the total fuel.

21. The process according to claim 13, characterized in that: The height of combustion zone I is 10-25% of the height of the lime vertical kiln, the height of combustion zone II is 25-45% of the height of the lime vertical kiln, and the height of combustion zone III is 40-60% of the height of the lime vertical kiln.

22. The process according to claim 21, characterized in that: The height of combustion zone I is 12-20% of the height of the lime vertical kiln, the height of combustion zone II is 30-40% of the height of the lime vertical kiln, and the height of combustion zone III is 45-55% of the height of the lime vertical kiln.

23. A lime classification oxygen-enriched calcination system for the process described in any one of claims 1-22, characterized in that: The system includes a calcining chamber (1), a fuel delivery pipe (2), and a combustion-supporting gas delivery pipe (3); the calcining chamber (1) is divided into n combustion zones from top to bottom, and each combustion zone is independently connected to the fuel delivery pipe (2) and the combustion-supporting gas delivery pipe (3); the fuel delivery pipe (2) is connected to the fuel source (7); the uppermost combustion zone is connected to the oxygen-containing gas source (4) through the combustion-supporting gas delivery pipe (3), and the other combustion zones are connected to the low-oxygen gas source (5) through the combustion-supporting gas delivery pipe (3); the value of n is 2 to 8.

24. The lime graded oxygen-enriched calcination system according to claim 23, characterized in that: The value of n is between 2 and 5.

25. The lime graded oxygen-enriched calcination system according to claim 23, characterized in that: Valves are installed inside the fuel delivery pipeline (2) and the combustion-supporting gas delivery pipeline (3).

26. The lime graded oxygen-enriched calcination system according to claim 23, characterized in that: The calcination chamber (1) is divided into three combustion zones from top to bottom: combustion zone I (11), combustion zone II (12), and combustion zone III (13).

27. The lime graded oxygen-enriched calcination system according to claim 26, characterized in that: The height of combustion zone I (11) is 10-25% of the height of the lime vertical kiln, the height of combustion zone II (12) is 25-45% of the height of the lime vertical kiln, and the height of combustion zone III (13) is 40-60% of the height of the lime vertical kiln.

28. The lime graded oxygen-enriched calcination system according to claim 27, characterized in that: The height of combustion zone I (11) is 12-20% of the height of the lime vertical kiln, the height of combustion zone II (12) is 30-40% of the height of the lime vertical kiln, and the height of combustion zone III (13) is 45-55% of the height of the lime vertical kiln.

29. The lime graded oxygen-enriched calcination system according to claim 23, characterized in that: The calcining chamber (1) is equipped with a temperature detection device (6).

30. The lime graded oxygen-enriched calcination system according to claim 29, characterized in that: Inside the calcining chamber, along the height direction, the calcining chamber is divided into N planes from top to bottom. Each of the N planes is equipped with a temperature detection device (6), and the value of N is 2~30.

31. The lime graded oxygen-enriched calcination system according to claim 30, characterized in that: The value of N ranges from 5 to 25.

32. The lime graded oxygen-enriched calcination system according to claim 29, characterized in that: Each plane is equipped with M temperature detection devices (6), where M ranges from 1 to 15.

33. The lime graded oxygen-enriched calcination system according to claim 32, characterized in that: The value of M is 6 to 12.

34. The lime graded oxygen-enriched calcination system according to claim 32, characterized in that: Of the M points on the same plane, one is located at the center of the plane, and the other temperature detection devices are arranged in a circle around the central wall of the plane.

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