1. technical name

High-temperature raw gas purification and resource utilization technology based on special metal film dry smelting furnace.

2. scope of application

Under the working conditions of flue gas inlet particulate matter concentration ≤150g/m3, flue gas purification and resource utilization of submerged arc furnaces and similar submerged arc furnaces in black smelting, non-ferrous smelting, and chemical processes.

3. technical content

3.1 technical principle

The filter element material adopts the independently developed patented technology-iron-based fifth-generation membrane filter material. This material uses the Kirkendall effect and chemical reaction caused by partial diffusion between elements to form pores, making the material have both metal bonds and covalent bonds. The bond mixed bond structure has the characteristics of high temperature resistance, corrosion resistance, high precision, good thermal shock resistance, and processability, making up for the fact that ceramic membranes are prone to cracking in environments with large operating temperature fluctuations and cannot be used as high-temperature filter materials for submerged arc furnaces. Through membrane separation technology and equipment innovation, the high-temperature flue gas from the submerged arc furnace is filtered, separated and purified at high temperatures above the dew point of water vapor and tar. The high-temperature flue gas from the submerged arc furnace (containing dust of 50g/m3~150g/m3) is subjected to precise gas-solid separation at 550 ° C to obtain clean gas (containing dust of less than 10mg/m3). After recovering heat energy through a heat exchanger (at the same time obtaining pure tar by-products), it is sent to the user's place as chemical raw materials or gas for power generation. Based on the 36000kVA closed-closed furnace design, the air volume of a single dust removal device is 8000m3/h ~14000m3/h; the operating temperature of the dust remover is ≤550℃; the high-temperature filtration accuracy reaches 0.1μm; and the dust remover resistance is 2 kPa. The process flow is shown in Figure 1: The high-temperature raw gas (mainly containing H2O, H2, CO, CO2, N2 and dust, etc.) generated from the closed submerged arc furnace is passed through a gravity dust collector to remove large particles of dust, and then enters an intermetallic compound membrane filter. Filter, the dust content of the gas meets the customer's requirements, and then is further cooled by an air-cooled heat exchanger and sent to a gas holder for storage through a high-temperature induced draft fan. Finally, the clean gas is transported by the gas holder to the ore sintering process as fuel or other users, realizing energy conservation and utilization.

3.2 main innovations

(1) It was the first to use the Kirkendall effect caused by partial diffusion between elements to prepare intermetallic compound porous membrane materials, solving the material problem in the field of high-temperature gas filtration. The partial diffusion reaction synthesis technology based on the atomic scale can achieve precise control of the pore structure at the micron/submicron level, making the material have good filtration properties such as uniform pore size distribution, high filtration accuracy, high porosity, small tortuosity factor and low filtration resistance. (2) Based on the characteristics of high-temperature raw gas flue gas from submerged arc furnaces, a high-temperature membrane separation technology system has been built, and filter media phase change prevention and control technology have been formed, which has realized stable and unstable gas and dust at high temperatures. Effective filtration; high-temperature backblowing technology, anti-bridge technology, filter cake layer control technology, special working condition control technology, membrane element online and offline regeneration technology have been formed to effectively control membrane pollution.

4. Pollution control or environmental restoration effects

After filtering, the high-temperature raw gas has a particulate matter concentration of ≤10mg/m3, and all the gas containing 70% CO-is recycled. Taking the Jiangyuan Ferroalloy Closed Submerged Arc Furnace Project in Jihua, Qinghai Province as an example, it has achieved annual emission reduction of nearly 1800 tons of particulate matter, recycled smelting gas to convert about 19200 tons of standard coal throughout the year, saved electricity to convert about 2300 tons of standard coal, and reduced emissions of 13,000 tons of CO2.

5. Technology demonstration

This technology has been applied to a total of 50 sets of equipment. Typical cases are Qinghai Jihua Jiangyuan Industrial Co., Ltd. 500,000 t/a ferrochromium alloy closed submerged arc furnace high temperature gas purification and recycling project, and Pangang Group Titanium Industry Co., Ltd. Titanium Smelter 2×25500kVA high-titanium slag submerged arc furnace gas recycling project. Taking the Qinghai project as an example, the high-temperature raw gas (mainly containing H2O, H2, CO, CO2, N2 and dust) generated from two 25500kVA closed submerged arc furnaces is removed through a gravity dust collector to remove large particles of dust, and then enters an intermetallic compound membrane filter for filtration. The dust content of the gas meets customer requirements. After further cooling by an air-cooled heat exchanger, it is sent to a gas holder for storage through a high-temperature induced draft fan. Finally, the clean gas is transported by the gas holder to the ore sintering process as fuel or other users, realizing energy conservation and utilization. This technology solves the technical problem of filtering, purifying and recycling high-temperature gases above 550℃, and realizes energy-saving and environmentally friendly production in the ferroalloy industry and the comprehensive utilization of submerged arc furnace flue gas.

6. investment estimation

Qinghai Jihua Jiangyuan Industrial Co., Ltd. has a total investment of 29.48 million yuan in the high-temperature gas purification and recycling project of a 500,000 t/a ferrochrome alloy closed submerged arc furnace, including 20 million yuan in equipment manufacturing cost, 7 million yuan in civil engineering (steel structure) cost, and 2.48 million yuan in equipment installation cost.

7. investment recovery period

Qinghai Jihua Jiangyuan Industrial Co., Ltd. has a static recovery period of about 13 months for the 500,000 t/a ferrochrome alloy closed submerged arc furnace high-temperature gas purification and recycling project.

8. Prospects for transformation and promotion of technological achievements

This technology can be widely used in purifying high-temperature raw gas in submerged arc furnaces and similar submerged arc furnaces, non-ferrous smelting, coal chemical industry, phosphorus chemical industry, titanium chemical industry, hazardous waste disposal and other industries, and has broad promotion prospects.