CN105000811B - A CO2 enrichment-based parallel flow regenerative lime kiln production process - Google Patents

Abstract

The invention discloses a parallel flow heat accumulating type lime kiln production technology based on CO2 accumulation. The parallel flow heat accumulating type lime kiln production technology includes the steps that limestone raw materials are fed into two kiln chambers of a parallel flow heat accumulating type lime kiln; carrier gas is sprayed into the kiln chambers; combustion supporting gas is fed; in a combustion zone of the current kiln chamber, limestone absorbs the heat generated by fuel combustion to be decomposed to generate quick lime and CO2 gas; the quick lime is discharged after being cooled to 80 DEG C to 100 DEG C; cooling gas, the CO2 gas generated by decomposing the limestone and CO2 gas generated by fuel combustion are mixed to enter the other kiln chamber to preheat limestone; flue gas generated by preheating releases heat to the limestone, then the temperature of the flue gas is reduced, the flue gas is exhausted, and CO2 gas with the volume concentration larger than 95% is generated; the parallel flow heat accumulating type lime kiln starts reversing work. By means of the parallel flow heat accumulating type lime kiln production technology, the high-purity CO2 gas is obtained while the high-quality lime is prepared. Compared with an existing technology, circulation of N2 in a system is avoided, the energy used for heating the N2 is saved, and the flue gas is recycled to achieve the aims of increasing the product added value, saving energy and reducing consumption.

Description

A CO2 enrichment-based parallel flow regenerative lime kiln production process

technical field

The invention relates to a production process of a lime kiln, in particular to a production process of a parallel flow regenerative lime kiln based on _CO2 enrichment.

Background technique

In the metallurgical industry, a large amount of CO ₂ is produced during the production of slagging material quicklime. In actual production, producing 1 ton of quicklime produces more than 1 ton of CO ₂ , and smelting 1 ton of steel requires about 70 kg of quicklime. In 2014, China's crude steel output was about 820 million tons, and about 57 million tons of quicklime was needed, which produced more than 60 million tons of CO ₂ . At present, lime kilns are mostly used to produce quicklime, but the CO ₂ content in the exhaust gas discharged from the lime kilns is very low. If CO ₂ is to be enriched and recycled, it will cost a large part of energy and capital, so most enterprises Choose direct discharge, which has caused a very serious environmental problem.

At present, most domestic co-current regenerative lime kilns use compressed air to transport pulverized coal, support combustion and cool products. The CO ₂ concentration in the generated flue gas is low (volume concentration 10-14%) and the flue gas volume is large. Due to the high cost of separating the waste gas with low _CO2 content after recovering the flue gas, most enterprises directly discharge the flue gas into the atmosphere, causing serious air pollution and waste of resources.

Contents of the invention

Aiming at the problems existing in the existing process, the present invention provides a co-current regenerative lime kiln production process based on _CO2 enrichment.

Technical scheme of the present invention is:

A kind of parallel flow regenerative lime kiln production process method based on _CO enrichment, comprising the following steps:

(1) In the first combustion cycle, the limestone raw material is transported from the stone silo in front of the kiln to the weighing hopper, and the limestone raw material is weighed by the weighing hopper and then loaded into the feed truck and transported to the roof of the parallel flow regenerative lime kiln. Enter the two kiln chambers of the co-current regenerative lime kiln;

(2) The fuel spray gun in a kiln chamber of the co-current regenerative lime kiln is inserted into the limestone column, and the carrier gas carries the fuel and is sprayed into the kiln chamber by the fuel spray gun;

(3) The combustion-supporting gas is supplied from the top of the co-current regenerative lime kiln through the combustion-supporting fan, and under the suction of the combustion-supporting fan, the combustion-supporting gas flows downward to the combustion zone and meets the fuel, so that the fuel burns under the nozzle of the fuel spray gun ;

(4) In the combustion zone of the current kiln, limestone absorbs the heat generated by fuel combustion and decomposes to produce quicklime and _CO2 gas;

(5) The quicklime produced in the combustion zone of the current kiln is cooled to 80°C~100°C by the cooling gas supplied by the cooling fan before being discharged;

(6) The cooling gas rises to the connecting channel after being heated by quicklime, mixes with the CO ₂ gas generated by the decomposition of limestone and the CO ₂ gas generated by fuel combustion, enters another kiln through the connecting channel and rises, passes through the combustion zone and enters the preheating zone Preheating the limestone;

(7) The flue gas produced by preheating releases heat to the limestone and then the temperature is lowered and discharged. After dust removal and purification, CO _{2 gas with a volume concentration greater than 95% is produced. Part of the CO 2 gas} is used as the carrier gas for fuel delivery, and the other part is As the cooling gas fed into the cooling zone by the cooling fan, the rest is directly stored or made into dry ice products;

(8) After the first calcination cycle is completed, the various airflows in the parallel flow regenerative lime kiln stop flowing, and the parallel flow regenerative lime kiln starts to reverse. The kiln bottom of the type lime kiln is unloaded.

The combustion-supporting gas in step (3) is oxygen-enriched with an oxygen concentration >95%.

30%-35% of the CO ₂ gas in the volume concentration greater than 95% of the CO ₂ gas in the step (7) is directly stored or made into a dry ice product.

5%-10% of the CO ₂ gas with a volume concentration greater than 95% in the step (7) is used as the carrier gas for transporting fuel.

55%-65% of the CO ₂ gas whose volume concentration is greater than 95% in the step (7) is used as the cooling gas supplied to the combustion zone by the cooling fan.

Beneficial effect:

The present invention provides a CO ₂ enrichment-based parallel flow regenerative lime kiln production process. This parallel flow regenerative lime kiln production process with the CO ₂ enrichment function can produce high-quality lime while also producing high-quality lime. purity of _CO2 gas. Compared with the existing process method, the circulation of N ₂ in the system is eliminated, the energy for heating N ₂ is saved, and the flue gas is recycled to achieve the goals of increasing product added value, saving energy and reducing consumption.

Description of drawings

Fig. 1 is a schematic structural diagram of a co-current regenerative lime kiln system based on _CO2 enrichment used in an embodiment of the present invention.

detailed description

The specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings.

Example 1

The structure of the co-current regenerative lime kiln system based on _CO2 enrichment in this example is shown in Figure 1. The dust removal device used in the system is a bag filter, and the fuel is pulverized coal. The dust concentration of the flue gas discharged from the exhaust port is ≤50mg/Nm ³ .

The above-mentioned parallel flow regenerative lime kiln system is used to produce quicklime (CaO). The daily output of quicklime is 450 tons, 80 production cycles per day, the amount of pulverized coal per production cycle is 240 kg~270kg, and the excess coefficient of combustion air is 1.1~1.4.

The production process method of parallel flow regenerative lime kiln based on _CO2 enrichment comprises the following steps:

(1) In the first combustion cycle, the limestone raw material is transported from the stone silo in front of the kiln to the weighing hopper, and the limestone raw material is weighed by the weighing hopper and then loaded into the feed truck and transported to the roof of the parallel flow regenerative lime kiln. Enter the two kiln chambers (Kiln Chamber 1 and Kiln Chamber 2) of the co-current regenerative lime kiln;

Specific feeding process: Limestone is sent from the underground receiving bin to the large-angle belt through the electric vibrating feeder, and the limestone is transported to the single-layer stone vibrating screen by the large-angle belt for screening, and the crushed stone is screened to the waste rock bin For other purposes, qualified limestone passes through the vibrating screen from the chute to the middle belt, and then from the middle belt to the stone silo in front of the kiln. The qualified limestone in the kiln front warehouse is sent to the hopper of the winch hoist after being weighed by the weighing hopper in front of the kiln. The limestone is fed into the rotary distributor installed on the two kiln barrels, and finally the limestone is sent into the kiln by the distributor.

(2) The fuel spray gun in one kiln chamber (kiln chamber 1) of the co-current regenerative lime kiln is inserted into the limestone material column, and the carrier gas carries the fuel and is sprayed into the kiln chamber by the fuel spray gun;

(3) Through the combustion-supporting fan, the oxygen-enriched oxygen with an oxygen concentration > 95% is supplied as a combustion-supporting gas from the roof of the parallel-flow regenerative lime kiln. Under the suction of the combustion-supporting fan, the combustion-supporting gas flows downward to the combustion zone to meet the fuel. Burn the fuel below the nozzle of the fuel lance;

(4) In the combustion zone of the current kiln chamber (Kiln Chamber 1), limestone absorbs the heat generated by fuel combustion and decomposes to produce quicklime and CO ₂ gas;

(5) The quicklime produced in the combustion zone of the current kiln chamber (kiln chamber 1) is cooled to 80°C~100°C by the cooling gas supplied by the cooling fan before being discharged;

When kiln chamber 1 is calcined, pulverized coal is sprayed into kiln chamber 1 through fuel nozzle, CO ₂ supporting gas (carrier gas for fuel delivery) is injected from kiln top, and CO ₂ cooling gas (by The cooling fan feeds the cooling gas into the combustion zone), and the _CO2 cooling gas cools the high-temperature CaO with a temperature of 1000°C to 1150°C to 80°C to 100°C.

(6) The cooling gas rises to the connecting channel after being heated by quicklime, mixes with the CO ₂ gas generated by the decomposition of limestone and the CO ₂ gas generated by fuel combustion, enters another kiln chamber (kiln chamber 2) through the connecting channel and rises, after burning Take it into the preheating zone to preheat the limestone;

(7) The flue gas generated by preheating releases heat to the limestone and then the temperature is lowered and discharged. After dust removal and purification, CO _{2 gas with a volume concentration greater than 95% is produced, and 5% of the CO 2 gas} is used as the carrier gas for transporting fuel, 65 % as the cooling gas supplied by the cooling fan to the cooling zone, and the remaining 30% is directly stored or made into dry ice products;

(8) After the first calcination cycle is completed, the various airflows in the parallel flow regenerative lime kiln stop flowing, and the parallel flow regenerative lime kiln starts to reverse. The bottom of the kiln chamber is unloaded.

Reversing work: the position of the combustion air reversing valve is changed, the combustion air release valve is opened, the cooling air release valve is opened, and the discharge gate is opened.

The amount of _CO discharged by the parallel flow regenerative lime kiln with 450 tons of daily lime per day is 385-415 tons. After the method of the present invention, the amount of flue gas that enters the part of the air compressor for recycling is 231-270 tons. The stored flue gas volume is 164~184 tons, which reduces flue gas emissions and environmental pollution.

Example 2

The structure of the co-current regenerative lime kiln system based on _CO2 enrichment in this example is shown in Figure 1. The dust removal device used in the system is a bag filter, and the fuel is pulverized coal. The dust concentration of the flue gas discharged from the exhaust port is ≤50mg/Nm ³ .

The above parallel flow regenerative lime kiln system is used to produce quicklime (CaO). The daily output of quicklime is 500 tons, 80 production cycles per day, the amount of pulverized coal per production cycle is 265kg~300kg, and the excess coefficient of combustion air is 1.1~1.4.

The production process method of parallel flow regenerative lime kiln based on _CO2 enrichment comprises the following steps:

(1) In the first combustion cycle, the limestone raw material is transported from the stone silo in front of the kiln to the weighing hopper, and the limestone raw material is weighed by the weighing hopper and then loaded into the feed truck and transported to the roof of the parallel flow regenerative lime kiln. Enter the two kiln chambers (Kiln Chamber 1 and Kiln Chamber 2) of the co-current regenerative lime kiln;

(2) The fuel spray gun in one kiln chamber (kiln chamber 1) of the co-current regenerative lime kiln is inserted into the limestone material column, and the carrier gas carries the fuel and is sprayed into the kiln chamber by the fuel spray gun;

(3) The combustion-supporting gas is supplied from the top of the co-current regenerative lime kiln through the combustion-supporting fan, and under the suction of the combustion-supporting fan, the combustion-supporting gas flows downward to the combustion zone and meets the fuel, so that the fuel burns under the nozzle of the fuel spray gun ; The combustion-supporting gas is oxygen-enriched with an oxygen concentration>95%;

(4) In the combustion zone of the current kiln chamber (Kiln Chamber 1), limestone absorbs the heat generated by fuel combustion and decomposes to produce quicklime and CO ₂ gas;

(5) The quicklime produced in the combustion zone of the current kiln chamber (kiln chamber 1) is cooled to 80°C~100°C by the cooling gas supplied by the cooling fan before being discharged;

When kiln chamber 1 is calcined, pulverized coal is sprayed into kiln chamber 1 through fuel nozzle, CO ₂ supporting gas (carrier gas for fuel delivery) is injected from kiln top, and CO ₂ cooling gas (by The cooling fan feeds the cooling gas into the combustion zone), and the _CO2 cooling gas cools the high-temperature CaO with a temperature of 1000°C to 1150°C to 80°C to 100°C.

(6) The cooling gas rises to the connecting channel after being heated by quicklime, mixes with the CO ₂ gas generated by the decomposition of limestone and the CO ₂ gas generated by fuel combustion, enters another kiln chamber (kiln chamber 2) through the connecting channel and rises, after burning Take it into the preheating zone to preheat the limestone;

(7) The flue gas generated by preheating releases heat to the limestone and then the temperature is lowered and discharged. After dust removal and purification, CO _{2 gas with a volume concentration greater than 95% is produced, and 10% of the CO 2 gas} is used as the carrier gas for transporting fuel, 55 % as the cooling gas supplied by the cooling fan to the cooling zone, and the remaining 35% is directly stored or made into dry ice products;

(8) After the first calcination cycle is completed, all kinds of air flow in the parallel flow regenerative lime kiln stop flowing, and the parallel flow regenerative lime kiln starts to reverse. The bottom of the kiln chamber is unloaded.

Reversing work: the position of the combustion air reversing valve is changed, the combustion air release valve is opened, the cooling air release valve is opened, and the discharge gate is opened.

The amount of _CO discharged by the parallel flow regenerative lime kiln with 500 tons of daily lime per day is 425-460 tons. After the method of the present invention, the amount of flue gas recycled into the part of the air compressor is 255-276 tons. The stored flue gas volume is 170~184 tons, which reduces flue gas emissions and environmental pollution.

Example 3

The structure of the co-current regenerative lime kiln system based on _CO2 enrichment in this example is shown in Figure 1. The dust removal device used in the system is a bag filter, and the fuel is pulverized coal. The dust concentration of the flue gas discharged from the exhaust port is ≤50mg/Nm ³ .

The above parallel flow regenerative lime kiln system is used to produce quicklime (CaO). The daily output of quicklime is 550 tons, 80 production cycles per day, the amount of pulverized coal per production cycle is 290 kg ~ 330 kg, and the excess coefficient of combustion air is 1.1 ~ 1.4.

The production process method of parallel flow regenerative lime kiln based on _CO2 enrichment comprises the following steps:

(1) In the first combustion cycle, the limestone raw material is transported from the stone silo in front of the kiln to the weighing hopper, and the limestone raw material is weighed by the weighing hopper and then loaded into the feed truck and transported to the roof of the parallel flow regenerative lime kiln. Enter the two kiln chambers (Kiln Chamber 1 and Kiln Chamber 2) of the co-current regenerative lime kiln;

(2) The fuel spray gun in one kiln chamber (kiln chamber 1) of the co-current regenerative lime kiln is inserted into the limestone material column, and the carrier gas carries the fuel and is sprayed into the kiln chamber by the fuel spray gun;

(3) The combustion-supporting gas is supplied from the top of the co-current regenerative lime kiln through the combustion-supporting fan, and under the suction of the combustion-supporting fan, the combustion-supporting gas flows downward to the combustion zone and meets the fuel, so that the fuel burns under the nozzle of the fuel spray gun ; The combustion-supporting gas is oxygen-enriched with an oxygen concentration>95%;

(4) In the combustion zone of the current kiln chamber (Kiln Chamber 1), limestone absorbs the heat generated by fuel combustion and decomposes to produce quicklime and CO ₂ gas;

(5) The quicklime produced in the combustion zone of the current kiln chamber (kiln chamber 1) is cooled to 80°C~100°C by the cooling gas supplied by the cooling fan before being discharged;

When kiln chamber 1 is calcined, pulverized coal is sprayed into kiln chamber 1 through fuel nozzle, CO ₂ supporting gas (carrier gas for fuel delivery) is injected from kiln top, and CO ₂ cooling gas (by The cooling fan feeds the cooling gas into the combustion zone), and the _CO2 cooling gas cools the high-temperature CaO with a temperature of 1000°C to 1150°C to 80°C to 100°C.

(6) The cooling gas rises to the connecting channel after being heated by quicklime, mixes with the CO ₂ gas generated by the decomposition of limestone and the CO ₂ gas generated by fuel combustion, enters another kiln chamber (kiln chamber 2) through the connecting channel and rises, after burning Take it into the preheating zone to preheat the limestone;

(7) The flue gas generated by preheating releases heat to the limestone and then the temperature is lowered and discharged. After dust removal and purification, CO _{2 gas with a volume concentration greater than 95% is produced, and 8% of the CO 2 gas} is used as the carrier gas for transporting fuel, 60 % is used as the cooling gas supplied to the cooling zone by the cooling fan, and the remaining 32% is directly stored or made into dry ice products;

(8) After the first calcination cycle is completed, the various airflows in the parallel flow regenerative lime kiln stop flowing, and the parallel flow regenerative lime kiln starts to reverse. The kiln chamber bottom of the kiln is unloaded.

Reversing work: the position of the combustion air reversing valve is changed, the combustion air release valve is opened, the cooling air release valve is opened, and the discharge gate is opened.

The amount of _CO discharged by the parallel flow regenerative lime kiln with 450 tons of daily lime per day is 470 to 510 tons. After the method of the present invention, the amount of flue gas recycled into the part of the air compressor is 282 to 306 tons. The stored flue gas volume is 188~204 tons, which reduces flue gas emissions and environmental pollution.

Claims (5)

1. A parallel flow regenerative lime kiln production process based on _CO2 enrichment, characterized in that, may further comprise the steps: (1) In the first combustion cycle, the limestone raw material is transported from the stone silo in front of the kiln to the weighing hopper, and the limestone raw material is weighed by the weighing hopper and then loaded into the feed truck and transported to the roof of the parallel flow regenerative lime kiln. Enter the two kiln chambers of the co-current regenerative lime kiln; (2) The fuel spray gun in a kiln chamber of the co-current regenerative lime kiln is inserted into the limestone column, and the carrier gas carries the fuel and is sprayed into the kiln chamber by the fuel spray gun; (3) The combustion-supporting gas is supplied from the top of the co-current regenerative lime kiln through the combustion-supporting fan, and under the suction of the combustion-supporting fan, the combustion-supporting gas flows downward to the combustion zone and meets the fuel, so that the fuel burns under the nozzle of the fuel spray gun ; (4) In the combustion zone of the current kiln, limestone absorbs the heat generated by fuel combustion and decomposes to produce quicklime and _CO2 gas; (5) The quicklime produced in the combustion zone of the current kiln is cooled to 80°C~100°C by the cooling gas supplied by the cooling fan before being discharged; (6) The cooling gas rises to the connecting channel after being heated by quicklime, mixes with the CO ₂ gas generated by the decomposition of limestone and the CO ₂ gas generated by fuel combustion, enters another kiln through the connecting channel and rises, passes through the combustion zone and enters the preheating zone Preheating the limestone; (7) The flue gas produced by preheating releases heat to the limestone and then the temperature is lowered and discharged. After dust removal and purification, CO _{2 gas with a volume concentration greater than 95% is produced. Part of the CO 2 gas} is used as the carrier gas for fuel delivery, and the other part is As the cooling gas fed into the cooling zone by the cooling fan, the rest is directly stored or made into dry ice products; (8) After the first calcination cycle is completed, the various airflows in the parallel flow regenerative lime kiln stop flowing, and the parallel flow regenerative lime kiln starts to reverse. The kiln bottom of the type lime kiln is unloaded. 2. The CO ₂ enrichment-based parallel flow regenerative lime kiln production process according to claim 1, characterized in that the combustion-supporting gas in step (3) is oxygen-enriched with an oxygen concentration > 95%. 3. The CO ₂ enrichment based co-current regenerative lime kiln production process method according to claim 1, characterized in that the CO ₂ gas with a volume concentration greater than 95% in the step (7) 30%~35% _CO2 gas is directly stored or made into dry ice products. 4. The CO ₂ enrichment based parallel flow regenerative lime kiln production process according to claim 1 or 3, characterized in that the CO ₂ with a volume concentration greater than 95% in the step (7) 5%~10% of the gas is used as carrier gas for fuel delivery. 5. The CO ₂ enrichment based parallel flow regenerative lime kiln production process according to claim 1 or 3, characterized in that the volume concentration of CO ₂ in the step (7) is greater than 95%. 55%~65% of the gas is used as the cooling gas supplied to the cooling zone by the cooling fan.