System for preparing calcium oxide by using carbide slag and application method

Abstract

The invention discloses a system for preparing calcium oxide from carbide slag and an application method.The system comprises a multi-stage cyclone preheater, a heat exchanger, a cyclone separator, a suspension reactor and a multi-stage cyclone cooler which are sequentially connected, and the multi-stage cyclone preheater is connected with the heat exchanger and the suspension reactor through pipelines; the cyclone separator is respectively connected with the heat exchanger and the multi-stage cyclone cooler through pipelines; and an air outlet of the multi-stage cyclone cooler is connected with the suspension reactor. Hot flue gas generated by the suspension reactor is used for preheating air through the heat exchanger to serve as a carbide slag preheating heat source, calcium oxide cooling air serves as combustion-supporting air of the suspension reactor, carbide slag carbonization is effectively avoided while waste heat is fully utilized, the heat efficiency is high, the reaction conversion rate is high, and the system is stable and reliable; the method can be used for preparing calcium oxide by calcining carbide slag, and has good economic and social benefits.

Description

Technical Field

[0001] The invention relates to a system for preparing calcium oxide and an application method, and in particular to a system for preparing calcium oxide by utilizing carbide slag and an application method. Background Art

[0002] Carbide slag is the waste residue with calcium hydroxide as the main component after acetylene gas is obtained by hydrolysis of calcium carbide. Its chemical composition is mainly Ca(OH)2. The temperature at which calcium hydroxide in carbide slag begins to decompose significantly is about 390℃, and the temperature range for large-scale decomposition is between 390℃ and 650℃. Therefore, the calcination temperature can be controlled within 650℃ to meet the calcination requirements and produce calcium oxide.

[0003] At present, there are two main advanced production processes for preparing calcium oxide by calcining carbide slag: one process is represented by Jiangsu Lemon New Calcium Industry Development Co., Ltd., which uses a suspension roasting furnace composed of a multi-stage cyclone preheater, a suspension reactor, and a multi-stage cyclone cooler. Hot flue gas is used as a heat source to preheat and calcine calcium hydroxide to prepare calcium oxide. Since this process contains a large amount of CO2 in the flue gas, calcium hydroxide and CO2 in the flue gas undergo a carbonization reaction during the preheating process to produce calcium carbonate. The decomposition temperature is increased to 820°C, and the corresponding calcination temperature must be increased to 900°C to complete the decomposition of calcium carbonate. The temperature difference between calcining carbide slag and calcining limestone is not large. For example, the publication number is CN 111498885B (a method for producing active calcium oxide using carbide slag). Another process is represented by Xinjiang Kaisheng Building Materials Design Institute, which uses hot flue gas provided by a hot blast furnace to heat air to 600-650°C through a non-metallic heat exchanger, and uses hot air as a firing heat source to decompose calcium hydroxide to prepare calcium oxide. This process effectively avoids the phenomenon that carbide slag reacts with CO2 to form calcium carbonate during preheating and decomposition because the CO2 content in the heat source is extremely low. However, the reaction heat of calcium hydroxide decomposing into calcium oxide and water is 470 kcal / kg.CaO. It is achieved by only using the sensible heat of the part above 600°C in hot air. In theory, a large amount of hot air medium (about 30 kg / kg.CaO) is required, and the production efficiency is low. For example, the publication number is CN 113816412A (a method for sintering calcium oxide from carbide slag).

[0004] In general, the prior art does not fully utilize the characteristics of carbide slag to fundamentally propose a method for efficiently preparing calcium oxide from carbide slag. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a system for efficiently preparing calcium oxide using carbide slag;

[0006] The second object of the present invention is to provide an application method of the above-mentioned system for preparing calcium oxide using carbide slag.

[0007] Technical solution: The high-efficiency calcium oxide preparation system of carbide slag of the present invention comprises a multi-stage cyclone preheater for preheating the carbide slag, a heat exchanger, a cyclone separator, a suspension reactor and a multi-stage cyclone cooler, wherein the heat exchanger is provided with an air inlet, a hot flue gas inlet, an air outlet and a hot flue gas outlet; the air outlet of the heat exchanger is connected to the feed port of the multi-stage cyclone preheater so as to preheat the carbide slag with the hot air after heat exchange; the discharge port of the multi-stage cyclone preheater is connected to the feed port of the suspension reactor so as to feed the preheated carbide slag into the suspension reactor for reaction; the suspension The discharge port of the reactor is connected to the cyclone separator for gas-solid separation of the reaction products; the flue gas outlet of the cyclone separator is connected to the hot flue gas inlet of the heat exchanger for the hot flue gas to exchange heat with the air; the discharge port of the cyclone separator is connected to the feed port of the first-stage cyclone in the multi-stage cyclone cooler, and the cooling air inlet is connected to the feed port of the last-stage cyclone in the multi-stage cyclone cooler, so that the calcium oxide can perform multi-stage heat exchange with the cooling air in the multi-stage cyclone cooler; the air outlet of the multi-stage cyclone cooler is connected to the suspension reactor for providing hot air to the suspension reactor.

[0008] The air outlet of each stage cyclone in the multi-stage cyclone cooler is connected to the feed inlet of the previous stage cyclone; the air outlet of the first stage cyclone in the multi-stage cyclone cooler is connected to the suspension reactor.

[0009] Among them, the air outlet of the heat exchanger is connected to the feed port of the last cyclone in the multi-stage cyclone preheater to allow the hot air after heat exchange to preheat the calcium carbide slag; the air outlet of each cyclone is connected to the feed port of the previous cyclone; the air outlet of the first cyclone is connected to the outside world.

[0010] Wherein, the multi-stage cyclone preheater includes three or more stages of cyclones.

[0011] Among them, when the cyclone of the multi-stage cyclone preheater is divided into three levels, from top to bottom are the first-stage cyclone P1 to the third-stage cyclone P3, the discharge port of the first-stage cyclone P1 and the air outlet of the third-stage cyclone P3 are both connected to the feed port of the second-stage cyclone P2 through a pipeline, the discharge port of the second-stage cyclone P2 and the air outlet of the heat exchanger are both connected to the feed port of the third-stage cyclone P3 through a pipeline, the discharge port of the third-stage cyclone P3 is connected to the feed port of the suspension reactor, the air outlet of the second-stage cyclone P2 is connected to the feed port of the first-stage cyclone P1; the air outlet of the first-stage cyclone P1 is connected to the outside.

[0012] Wherein, the multi-stage cyclone cooler includes three or more stages of cyclone barrels.

[0013] Among them, when the cyclone of the multi-stage cyclone cooler is divided into three stages, from top to bottom, they are the first-stage cyclone C1 to the third-stage cyclone C3, the discharge port of the first-stage cyclone C1 and the air outlet of the third-stage cyclone C3 are both connected to the feed port of the second-stage cyclone C2 through a pipeline, the discharge port and the cooling air inlet of the second-stage cyclone C2 are both connected to the feed port of the third-stage cyclone C3 through a pipeline, the discharge port of the third-stage cyclone C3 is connected to the outside, the air outlet of the second-stage cyclone C2 and the discharge port of the cyclone separator are connected to the feed port of the first-stage cyclone C1; the air outlet of the first-stage cyclone C1 is connected to the suspension reactor through a pipeline.

[0014] The suspension reactor is provided with a solid material outlet and a gas material outlet, both of which are connected to the feed inlet of the cyclone separator for gas-solid separation of the reaction products.

[0015] The application method of the above-mentioned high-efficiency carbide slag preparation calcium oxide system comprises the following steps:

[0016] (A) The hot flue gas at the outlet of the suspension reactor has a temperature of 700-750°C. After heat exchange with air in the heat exchanger, the temperature drops to 130°C and is discharged from the system; the air is heated to 650-700°C, and the obtained hot air enters the multi-stage cyclone preheater as a preheating heat source for carbide slag; at the same time, the carbide slag powder is fed into the feed port of the first-stage cyclone P1 of the multi-stage cyclone preheater, and the carbide slag preheated by the preheater enters the suspension reactor for calcination, and the exhaust gas from the first-stage cyclone P1 is discharged from the system;

[0017] (B) The carbide slag entering the suspension reactor is calcined at 700-750°C and decomposed into calcium oxide and water vapor. The decomposed calcium oxide enters the cyclone separator with the flue gas for gas-solid separation. The calcium oxide enters the first-stage cyclone C1 feed port of the multi-stage cyclone cooler through the cyclone separator feed pipe, and the water vapor enters the heat exchanger with the flue gas.

[0018] (C) The calcium oxide entering the multi-stage cyclone cooler exchanges heat with the cooling air at the inlet of the third-stage cyclone C3 step by step through the multi-stage cyclone cooler. After the air is preheated, it enters the suspension reactor to assist combustion. After the calcium oxide is cooled, it is stored as a finished product.

[0019] Among them, in step (A), the carbide slag preheated by the preheater has a temperature of 450-500°C and enters the suspension reactor for calcination, and the exhaust gas temperature out of the first-stage cyclone P1 is ≤150°C and is discharged from the system.

[0020] Wherein, in step (C), air is preheated to 450-500°C and enters the suspension reactor to assist combustion, and calcium oxide is cooled to 80-100°C and stored as a finished product.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: The present invention uses hot flue gas to preheat air as a heat source for preheating carbide slag through a heat exchanger, making full use of waste heat while effectively avoiding carbonization of carbide slag, thereby reducing the calcination decomposition temperature to 700-750°C. The heat provided by direct combustion of fuel is used as reaction heat, and the amount of combustion-supporting air only needs 0.8-0.9kg / kg.CaO, with high thermal efficiency, and heat consumption can be reduced to 600-650kcal / kg.CaO. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the system structure for preparing calcium oxide using carbide slag in the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in further detail below.

[0024] like Figure 1 As shown, the present invention provides a system for preparing calcium oxide by using carbide slag, comprising a multi-stage cyclone preheater 1, a heat exchanger 2, a cyclone separator 3, a suspension reactor 4 and a multi-stage cyclone cooler 5 which are sequentially connected through pipelines; the multi-stage cyclone preheater 1 is connected to the heat exchanger 2 and the suspension reactor 4 through pipelines, respectively, the cyclone separator 3 is connected to the heat exchanger 2 and the multi-stage cyclone cooler 5 through pipelines, respectively; the multi-stage cyclone cooler 5 is connected to the suspension reactor 4 through pipelines.

[0025] The heat exchanger 2 of this embodiment is a gas heat exchanger, and the heat exchanger 2 is provided with an air inlet, a hot flue gas inlet, an air outlet and a hot flue gas outlet. The cyclone separator 3 is provided with a feed inlet, a flue gas outlet and a discharge port. The suspension reactor 4 is provided with a feed inlet at the bottom, and a solid material outlet and a gas material outlet at the top. The solid material outlet and the gas material outlet are both connected to the feed inlet of the cyclone separator 3 for gas-solid separation of the products after the reaction. The flue gas outlet of the cyclone separator 3 of this embodiment is connected to the hot flue gas inlet of the heat exchanger 2. The high-temperature flue gas separated by the cyclone separator 3 enters through the hot flue gas inlet of the heat exchanger 2, and performs countercurrent heat exchange with the cooling air in the heat exchanger 2, which plays a role in heat recovery, and the preheated air enters the multi-stage cyclone preheater 1 from the air outlet, and is used as a heat source for preheating calcium carbide slag.

[0026] The multi-stage cyclone preheater 1 includes three or more cyclones. The present embodiment is a three-stage cyclone, which includes the first-stage cyclone P1 to the third-stage cyclone P3 from top to bottom. The discharge port of the first-stage cyclone P1 and the air outlet of the third-stage cyclone P3 are both connected to the feed port of the second-stage cyclone P2 through a pipeline, the discharge port of the second-stage cyclone P2 and the air outlet of the heat exchanger 2 are both connected to the feed port of the third-stage cyclone P3 through a pipeline, the discharge port of the third-stage cyclone P3 is connected to the feed port of the suspension reactor 4, the air outlet of the second-stage cyclone P2 is connected to the feed port of the first-stage cyclone P1; the air outlet of the first-stage cyclone P1 is connected to the outside.

[0027] The multi-stage cyclone cooler 5 includes three or more cyclones. The present embodiment is a three-stage cyclone, which includes the first-stage cyclone C1 to the third-stage cyclone C3 from top to bottom. The discharge port of the first-stage cyclone C1 and the air outlet of the third-stage cyclone C3 are both connected to the feed port of the second-stage cyclone C2 through a pipeline, the discharge port of the second-stage cyclone C2 and the cooling air inlet are both connected to the feed port of the third-stage cyclone C3 through a pipeline, the discharge port of the third-stage cyclone C3 is connected to the outside, the air outlet of the second-stage cyclone C2 and the discharge port of the cyclone separator 3 are connected to the feed port of the first-stage cyclone C1; the air outlet of the first-stage cyclone C1 is connected to the suspension reactor 4 through a pipeline, so as to deliver the hot air after heat exchange into the suspension reactor.

[0028] The application method of the system for preparing calcium oxide by utilizing carbide slag of the present invention comprises the following steps:

[0029] (1) The carbide slag enters the air inlet of the first-stage cyclone preheater P1 of the multi-stage cyclone preheater 1, undergoes gas-solid contact heat exchange, undergoes gas-solid separation in the first-stage cyclone preheater P1, then enters the air inlet of the second-stage cyclone preheater P2, undergoes gas-solid contact heat exchange, then enters the air inlet of the third-stage cyclone preheater P3, undergoes gas-solid contact heat exchange, is preheated to 450-500° C., then undergoes gas-solid separation in the third-stage cyclone preheater P3 and enters the suspension reactor 4;

[0030] (2) The preheated carbide slag is calcined at 700-750° C. in the suspension reactor 4. The calcined material is separated into gas and solid by the cyclone separator 3. The high-temperature flue gas at 700-750° C. is preheated by the heat exchanger 2 and discharged as waste gas. The air preheated to 650-700° C. is preheated by the third-stage cyclone preheater P3, the second-stage cyclone preheater P2, and the first-stage cyclone preheater P1 and then discharged as waste gas from the first-stage cyclone preheater P1. The high-temperature material at 700-750° C. enters the multi-stage cyclone cooler 5.

[0031] (3) The high-temperature material at 700-750°C enters the air inlet of the first-stage cyclone cooler C1 of the multi-stage cyclone cooler 5, undergoes gas-solid contact heat exchange, and then undergoes gas-solid separation in the first-stage cyclone cooler C1, and then enters the air inlet of the second-stage cyclone cooler C2, undergoes gas-solid contact heat exchange, and then enters the air inlet of the third-stage cyclone cooler C3, undergoes gas-solid contact heat exchange, and then cools to 80-100°C, and then undergoes gas-solid separation in the third-stage cyclone cooler C3 and is stored as a finished product. After the cooling air cools the material through the third-stage cyclone cooler C3, the second-stage cyclone cooler C2, and the first-stage cyclone cooler C1, the air is preheated to 450-500°C and enters the suspension reactor 4 as combustion air.

[0032] The present invention can effectively avoid the carbonization of carbide slag while making full use of waste heat, thereby reducing the calcination decomposition temperature to 700-750° C. The heat provided by direct combustion of fuel is used as reaction heat, and the amount of combustion-supporting air is only 0.8-0.9 kg / kg.CaO, with high thermal efficiency, and the heat consumption can be reduced to 600-650 kcal / kg.CaO.

Claims

1. A system for preparing calcium oxide using carbide slag, characterized in that: The invention comprises a multi-stage cyclone preheater (1) for preheating carbide slag, a heat exchanger (2), a cyclone separator (3), a suspension reactor (4) and a multi-stage cyclone cooler (5), wherein the heat exchanger is provided with an air inlet, a hot flue gas inlet, an air outlet and a hot flue gas outlet; the air outlet of the heat exchanger (2) is connected to the feed port of the multi-stage cyclone preheater (1) so that the hot air after heat exchange can preheat the carbide slag; the discharge port of the multi-stage cyclone preheater (1) is connected to the feed port of the suspension reactor (4) so ​​that the preheated carbide slag can be fed into the suspension reactor (4) for reaction; the discharge port of the suspension reactor (4) is connected to the feed port of the cyclone separator (3), so that the preheated carbide slag can be fed into the suspension reactor (4) for reaction; the discharge port of the suspension reactor (4) is connected to the feed port of the cyclone separator (4), so that the preheated carbide slag can be fed into the suspension reactor (4) for reaction; the discharge port of the suspension reactor (4) is connected to the feed port of the cyclone separator (5 ... cyclone separator (3) is The separator (3) is connected to perform gas-solid separation on the products after the reaction; the smoke outlet of the cyclone separator (3) is connected to the hot smoke inlet of the heat exchanger (2) to allow the hot smoke to exchange heat with the air; the discharge port of the cyclone separator (3) is connected to the feed port of the first-stage cyclone in the multi-stage cyclone cooler (5), and the cooling air inlet is connected to the feed port of the last-stage cyclone in the multi-stage cyclone cooler (5), so that the calcium oxide can perform multi-stage heat exchange with the cooling air in the multi-stage cyclone cooler (5); the air outlet of the multi-stage cyclone cooler (5) is connected to the suspension reactor (4) to provide hot air to the suspension reactor (4).

2. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: The air outlet of each stage cyclone in the multi-stage cyclone cooler (5) is connected to the feed inlet of the previous stage cyclone; and the air outlet of the first stage cyclone in the multi-stage cyclone cooler (5) is connected to the suspension reactor (4).

3. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: The air outlet of the heat exchanger (2) is connected to the feed port of the last cyclone in the multi-stage cyclone preheater (1) so that the hot air after heat exchange can preheat the calcium carbide slag; the air outlet of each cyclone is connected to the feed port of the previous cyclone; and the air outlet of the first cyclone is connected to the outside.

4. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: The multi-stage cyclone preheater (1) comprises three or more stages of cyclone barrels.

5. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: When the cyclone of the multi-stage cyclone preheater (1) is divided into three stages, from top to bottom, they are the first stage cyclone P1 to the third stage cyclone P3, the discharge port of the first stage cyclone P1 and the air outlet of the third stage cyclone P3 are both connected to the feed port of the second stage cyclone P2 through a pipeline, the discharge port of the second stage cyclone P2 and the air outlet of the heat exchanger (2) are both connected to the feed port of the third stage cyclone P3 through a pipeline, the discharge port of the third stage cyclone P3 is connected to the feed port of the suspension reactor (4), the air outlet of the second stage cyclone P2 is connected to the feed port of the first stage cyclone P1; the air outlet of the first stage cyclone P1 is connected to the outside.

6. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: The multi-stage cyclone cooler (5) comprises three or more stages of cyclone barrels.

7. The system for preparing calcium oxide using carbide slag according to claim 1, characterized in that: When the cyclones of the multi-stage cyclone cooler (5) are divided into three stages, from top to bottom, they are the first stage cyclone C1 to the third stage cyclone C3, the discharge port of the first stage cyclone C1 and the air outlet of the third stage cyclone C3 are both connected to the feed port of the second stage cyclone C2 through a pipeline, the discharge port and the cooling air inlet of the second stage cyclone C2 are both connected to the feed port of the third stage cyclone C3 through a pipeline, the discharge port of the third stage cyclone C3 is connected to the outside, the air outlet of the second stage cyclone C2 and the discharge port of the cyclone separator (3) are connected to the feed port of the first stage cyclone C1; the air outlet of the first stage cyclone C1 is connected to the suspension reactor (4) through a pipeline.

8. An application method of the system for preparing calcium oxide by utilizing carbide slag according to claim 1, characterized in that: The following steps are involved: (A) The hot flue gas at the outlet of the suspension reactor (4) has a temperature of 700-750°C. After heat exchange with air in the heat exchanger (2), the temperature is reduced to 130°C and discharged from the system; the air is heated to 650-700°C, and the obtained hot air enters the multi-stage cyclone preheater (1) as a preheating heat source for carbide slag; at the same time, the carbide slag powder is fed into the feed port of the first stage cyclone P1 of the multi-stage cyclone preheater (1), and the carbide slag preheated by the preheater enters the suspension reactor (4) for calcination, and then exits the exhaust gas discharge system of the first stage cyclone P1; (B) The carbide slag entering the suspension reactor is calcined at a high temperature of 700-750°C and decomposed into calcium oxide and water vapor. The decomposed calcium oxide enters the cyclone separator (3) with the flue gas for gas-solid separation. The calcium oxide enters the feed port of the first-stage cyclone C1 of the multi-stage cyclone cooler (5) through the discharge pipe of the cyclone separator (3), and the water vapor enters the heat exchanger with the flue gas. (C) The calcium oxide entering the multi-stage cyclone cooler (5) exchanges heat with the cooling air at the inlet of the third-stage cyclone C3 step by step through the multi-stage cyclone cooler (5). After the air is preheated, it enters the suspension reactor (4) to assist combustion. After the calcium oxide is cooled, it is stored as a finished product.

9. The application method of the system for preparing calcium oxide by utilizing carbide slag according to claim 8, characterized in that: In step (A), the carbide slag preheated by the preheater has a temperature of 450-500°C and enters the suspension reactor (4) for calcination. The waste gas temperature out of the first-stage cyclone P1 is ≤150°C and is discharged from the system.

10. The application method of the system for preparing calcium oxide by utilizing carbide slag according to claim 8, characterized in that: In step (C), air is preheated to 450-500°C and enters the suspension reactor (4) for combustion support, and the calcium oxide is cooled to 80-100°C and stored as a finished product.

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