Total oxygen smelting method for heating coal gas through plasma

Abstract

The invention discloses an all-oxygen smelting method of plasma heating coal gas, which is implemented according to the following steps: 1, blowing pure oxygen from a tuyere to enable the pure oxygen to react with coke to generate heat, and simultaneously generating low-nitrogen or even nitrogen-free coal gas at the top of the furnace; 2, after pure oxygen is blown into the tuyere, low-nitrogen coal gas output by the blast furnace is divided into two parts after carbon dioxide is removed, one part of coal gas serves as cold coal gas and is sprayed into the furnace again from the tuyere, so that high-temperature coal gas in a hearth can bring heat to a block-shaped area at the middle-upper part of the blast furnace, and the reduction reaction of ore is completed; heating the other part of the coal gas without the carbon dioxide to 2500 DEG C by adopting a plasma torch, mixing the heated high-temperature coal gas with oxygen and the cold coal gas, regulating the temperature to 1500 DEG C, and spraying into the furnace from a tuyere; and 3, in order to ensure the safety of the gas heating system, the gas inlet pipeline in the step 2 is connected with a nitrogen switching pipeline, so that the safe operation of the system is realized.

Description

Technical Field

[0001] The present invention relates to a method for all-oxygen smelting by plasma heating of coal gas. Background Art

[0002] Blast furnace ironmaking has experienced a development process of more than 200 years. With its high thermal efficiency and high production capacity, it occupies nearly 90% of the hot metal production capacity in China and has made great contributions to the development of the national economy and human civilization. However, the carbon utilization efficiency of the blast furnace ironmaking process is low, averaging less than 65%, which is also the main reason for the high carbon emissions of traditional blast furnace ironmaking. To achieve carbon emission reduction in blast furnace ironmaking, it is necessary to improve the carbon utilization efficiency of the blast furnace. Recycling the blast furnace output gas is one of the effective ways to improve the carbon utilization rate. However, 78% of the traditional blast furnace blast is nitrogen, and the nitrogen content in the output gas is high, making it not suitable for recycling. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for all-oxygen smelting by plasma heating of coal gas. The temperature of the coal gas is increased to 1500 °C by plasma heating and then sprayed into the hearth from the tuyere to realize the reuse of the blast furnace output gas, achieve the purpose of maximizing the carbon utilization efficiency of the blast furnace, and reduce the carbon emissions of blast furnace ironmaking.

[0004] Specifically, the present invention is realized by the following technical solution: A method for all-oxygen smelting by plasma heating of coal gas is implemented according to the following steps: 1. Blow pure oxygen from the tuyere to react with coke to generate heat, and at the same time generate low-nitrogen or even nitrogen-free gas at the top of the furnace; 2. After blowing pure oxygen from the tuyere, the low-nitrogen gas output from the blast furnace is divided into two parts after removing carbon dioxide. One part of the gas is sprayed into the furnace again from the tuyere as cold gas, so that the high-temperature gas in the hearth can bring heat to the lumpy zone in the upper and middle parts of the blast furnace to complete the reduction reaction of the ore; the other part of the gas after removing carbon dioxide is heated to 2500 °C by a plasma torch. This part of the heated high-temperature gas is mixed with oxygen and the cold gas and adjusted to 1500 °C and then sprayed into the furnace from the tuyere; 3. To ensure the safety of the coal gas heating system, a nitrogen switching pipeline is connected to the coal gas inlet pipeline in step 2 to realize the safe operation of the system.

[0005] Key points of the method of the present invention: 1. Inject 100% oxygen into the blast furnace tuyere; 2. Reuse the blast furnace output gas after removing carbon dioxide; 3. The decarbonized gas is heated by a plasma torch. The gas output from the plasma torch can reach 2500°C. The gas volume entering the plasma torch is adjusted by one regulating valve, and the cold gas addition amount is adjusted by another regulating valve. Finally, the blown hot gas entering the blast furnace tuyere is adjusted to 1500°C. 4. When the system is abnormal or fails emergently, the nitrogen quick cut valve is opened and the gas quick cut valve is closed. The system enters the nitrogen purging and security state. Effect test of the method of the present invention: 1. The blast furnace adopts all-oxygen smelting, and the blast furnace output gas has low nitrogen or even no nitrogen, making the output gas have the technical conditions for carbon dioxide removal. 2. The all-oxygen smelting technology realizes that the blast furnace output gas is decarbonized and then injected into the furnace again from the tuyere, realizing the circular reuse of carbon resources and greatly improving the carbon utilization efficiency of the blast furnace process. The carbon consumption of the blast furnace process can be reduced by 30%. 3. Blowing the decarbonized gas at the tuyere adjusts the temperature of the hearth area of the tuyere zone and increases the gas generation amount in the hearth, ensuring the stable and smooth operation of the blast furnace. It also increases the amount of high-temperature reducing gas, creating conditions for high-efficiency and high-yield production of the blast furnace. 4. Using the plasma heating technology to heat the gas to 1500°C not only solves the problem of insufficient theoretical combustion temperature under large-scale blowing at the blast furnace tuyere, but also avoids the influence of carbon deposition reaction of highly reducing gas on the system. It ensures the safe, efficient and low-consumption operation of the system. Finally, the goal of reducing the carbon consumption of the blast furnace process by 40% can be achieved. The present invention is applicable to oxygen blast furnaces, EAFs and gas-based shaft furnace devices with all-oxygen smelting, which can greatly improve the carbon utilization efficiency of the process and reduce the carbon emission of the process. Embodiment

[0006] An all-oxygen smelting method for heating gas by plasma is implemented according to the following steps: 1. Blow pure oxygen from the tuyere to react with coke to generate heat, and at the same time generate low-nitrogen or even nitrogen-free gas at the furnace top; 2. After blowing pure oxygen from the tuyere, at the same time, the low-nitrogen gas output from the blast furnace is divided into two parts after removing carbon dioxide. One part of the gas is blown into the furnace again from the tuyere as cold gas, so that the high-temperature gas in the hearth can bring heat to the lump zone in the upper and middle parts of the blast furnace to complete the reduction reaction of the ore; the other part of the gas after removing carbon dioxide is heated to 2500°C by a plasma torch, and this part of the heated high-temperature gas is mixed with oxygen and the cold gas and adjusted to 1500°C and then blown into the furnace from the tuyere; 3. To ensure the safety of the gas heating system, a nitrogen switching pipeline is connected to the gas inlet pipeline in step 2 to realize the safe operation of the system.

Claims

1. A method for all-oxygen smelting of plasma-heated coal gas, characterized in that It is implemented according to the following steps:

1. Blow pure oxygen from the tuyere to react with coke to generate heat, and at the same time generate low-nitrogen or even nitrogen-free gas at the top of the furnace; 2. After blowing pure oxygen from the tuyere, the low-nitrogen gas output from the blast furnace is divided into two parts after removing carbon dioxide. One part of the gas is sprayed into the furnace again from the tuyere as cold gas, so that the high-temperature gas in the hearth can bring heat to the lump zone in the upper and middle parts of the blast furnace to complete the reduction reaction of the ore; the other part of the gas after removing carbon dioxide is heated to 2500 °C by a plasma torch, and this part of the heated high-temperature gas is mixed with oxygen and the above-mentioned cold gas and adjusted to 1500 °C and then sprayed into the furnace from the tuyere; 3. To ensure the safety of the gas heating system, a nitrogen switching pipeline is connected to the gas inlet pipeline in step 2 to achieve the safe operation of the system.