Exploration of Carrying out Environmental Treatment starting from Source by Systematic Optimization. Shandong Iron and Steel Group Co.,Ltd.

Transcription

1 Exploration of Carrying out Environmental Treatment starting from Source by Systematic Optimization Shandong Iron and Steel Group Co.,Ltd.

2 1. Brief introduction of Shandong Iron and Steel Group Co.,Ltd. Shandong Iron and Steel Group Co.,Ltd. is established and registered on Mar 17, It has 19 wholly-owned or holding subsidiaries companies, and controls 4 listed companies: Shandong Iron And Steel Company Ltd., Shandong Jinling Mining Co.,Ltd., Luyin Investment Group Co.,Ltd. and Luzheng Futures, while a company of Jinan Luxin Materials Co.,Ltd. listed on the new third board. Iron and steel industry is the core industry of Shandong Steel, of which the current production capacity is mainly distributed in Laiwu factory area and Zibo factory area. The main steel products include medium and thick plate, hot rolled sheet/coil, cold rolled sheet/coil, H beam, special and high quality steel, hot rolled ribbed bar, etc., which have been widely used in many industry field such as automobile, petroleum, railway, architecture, electric power, transportation, machinery, ship building, light industry, household electrical appliances and other important fields. The products have been sold to dozens of countries and regions.

3 2. Practice in low-carbon environmental protection In order to enhances the low-carbon environmental protection, Shandong Steel has carried out related technical research and optimise the system to protect the environment by managing the polluting source. The emission finally satisfied the third period pollutants emission concentration standard of Shandong provincial regional integrated emission standard of air pollutants. Many low carbon projects, such as raising power generation efficiency and improving residual heat have been conducted. In terms of environmental protection, projects such as raw material field closure, sintering machine closure, coking wastewater to be used to steelmaking evaporative cooling have been implemented.

4 2.1 Laiwu Steel old area sewage treatment plant The plant mainly treats the industrial wastewater and sanitary waste water came from the ironmaking plant, coking plant, energy and power plant, Cold rolled strip and the training center. It adopts A/O+BAF+ high-efficiency basin process by which the whole waste water can be treated very well to satisfy the discharging environmental standard. The indexes of the wastewater after treatment reaches up the value limits of Table 3-2 Direct Discharging Standard (COD<50mg/L,NH3- N<5mg/L,SS<20mg/L)of Shandong Provincial Iron and Steel Industry Pollutants Emission Standard.

5 2.2 Yongfeng Zibo Company raw material yard closure project The membrane structure, which utilises reticulated shell as the skeleton, is adopted to seal the raw material field. The engineering span is 111 m, which is a long span steel structure with reticulated shell structure. The spatial grid structure uses similar mesh to form spatial intersection member bar system, and the load-bearing structure and the supporting system are combined together as one system, which makes the force of the structure in a reasonable and stable state. Compared with using color plate as sealing material, using membrane have the advantages of economy, corrosion resistance, long service life, high transmittance, convenient installation and no maintenance.

6 2.3 Sintering Dry Flue Gas Comprehensive Removal of Pollutants with Carbon- based Catalyst in Rizhao Super Quality Iron and Steel Products Base Sintering dry flue gas integrative removal technology of multi-pollutants with carbon- based catalyst mainly consists of flue gas system, reactor system, first stage regenerator system, second regenerator system, first stage material delivery system, second stage material delivery system and auxiliary system. The design indexes, Particulate concentration <10mg/Nm 3, SO 2 concentration<50mg/nm 3, Nox concentration<100mg/nm 3, Dioxin concentration<0.5 ng-teq/nm 3, Pb concentration<0.9mg/nm 3, Fluoride concentration <4mg/Nm 3

7 3. Thoughts and Experiences Three principles of clean production: source reduction, process control, end treatment, among them source reduction is most effective one. Here takes sintering as an example to illustrate it. Basic situation of the sintering machines. Systematic optimization technical route of sintering machine system. Desired effect of systematic optimization.

8 3.1 Basic Situation of Sintering Machine Definition of Sintering Sintering is a method that various kinds of powdered iron contained raw materials are mixed with proper amount of fuel, flux and proper amount of water, and,after mixing and pelletizing, sintered on the sintering equipment with ignition, so that it can be sintered into blocks under the condition of incomplete melting. In this process, the high temperature produced by fuel combustion makes the material a series of physical, chemical changes, and produces a certain amount of liquid phase. When cooling, the liquid phase will bond the powder particles into blocks and form sinter.

9 3.1.2 Sintering principle heat transfer theory Rule of heat transferring in sintering process Rule of temperature distribution in material layer Heat storage phenomenon hydrodynamics Rule of gas movement in Sintering Process Analysis of the influence of the permeability of the material layer on the process parameters Solid fuel combustion Water evaporation and condensation Decomposition, redox Physical Chemistry and Crystal Mineralogy Solid phase reaction in sintering process Liquid phase formation and condensation Metallogenic mechanism and structural characteristics

10 3.1.3 Sintering characteristics Modern sintering production is mainly divided into two parts: raw material preparation and sintering. The main production line of sintering starts from batching, including burdening, mixing, sintering, cooling and finished sinter granulation, which is usually as long as several hundred meters. The sintering process carried out on the sintering machine lasts for a short time, and the ignition, fuel combustion, heat transfer and various liquid phase formation, cooling and recrystallization are completed in a few dozen minutes.

11 烧结工艺流程图

12 3.1.4 Sintering machine main equipment Sintering is generally divided into raw material system, processing system, batching system, mixing system, sintering system and product finishing system. The main equipments include piling and taking machine, crusher, vibrating screen, mixing tank, belt / plate conveyer, batching bin, pelletizer, burden distributor, sintering machine and so on.

13 system sintering machine flow chart Equipments Material system Processing system Primary material yard Secondary material yard lime Various iron-contained materialf flux fuel Pre-batching chamber Flattening and mixing Flux processing Flux system dedusting Fuel processing Fuel system dedusting Piling and taking machine Piling machine Taking machine Quantitative disc feeder Mixing piling machine Mixing taking machine Hammer crusher Elliptic vibrating screen Double-roll crusher Four-roll crusher Batching system batching Batching system dedusting Quantitative disc feeder Electric weigher Lime screwed feeder Mixing system Water,mixing,granulation,coal cladding Mixing machine Granulation machine Coal cladding machine Sintering system Sintering end dedusting Distribution,firing,sintering crushing Sintering head dedusting Exhausting Round roll feeder Nine-roll distributor Sintering machine Double-bevel igniter Main exhauster Single roll crusher Finsihing system Sintering finishing system dedusting Cooling,sizing,screening Ring cooling machine Elliptic vibrating screen BF

14 3.1.5 Pollutants from sintering machine Pollutants volume per ton of sinter production 序号 项目 数值 1 Gas temperature Dust concentration mg/m 3 3 Sulfur dioxide concentration 600~2000mg/m 3 4 Nitrogen oxide concentration 300~500mg/m 3 5 Dioxin concentration 2~13.5ng-TEQ/m 3

15 3.1.6 Pollutant types and treatment facilities Pollutant types Pollutants discharge points Pollutants names Treatment methods Sintering head and end gas and dust,so2,nox,co HF, heavy metal,dioxin Dry dedust,electric dedust,multi-tube dedust, Electric bag Composite dedust, integrated technology of desulfurization, denitrification and dioxin removal gaseous Pollutants material preparation system, batching system,mixing system, granulation system,heat sinter cooling system Dusts Punching wet dust collector, foam wet dust collector, cloth bag dust collector Water Pollutants wet collection dust wastewater SS-contained Centralized concentration treatment Solid waste pollutants Metallurgical sludge collected by dedusting system Dust mud back to sintering burden

16 3.2. Sintering machine system systematic optimization technical route Raw material storage technical route The modern large-scale raw materials storage field (raw material storage site) includes ore yard, coal yard, auxiliary raw material yard and blending yard. It stores not only iron ore, iron concentrate, pellets, manganese ores, limestone, dolomite, serpentine, silica, coking coal, thermal coal, but also some sinter, pellets and recycled materials in steel plants. For example, iron oxide, Blast furnace ash, broken coke, sintered powder, miscellaneous materials, etc.

17 Raw material storage system technical route The unorganized emission from raw material field is the main pollution source in sintering process. The effect of sprinkling water to control dust is not good. It is difficult to control the unorganized emission, meanwhile large amounts of resources are lost. Resolution technical route: 1)To close material field, let raw fuel and material unloading, crushing, material burdening, mixing and other operations in a closed space. 2) Bring mechanization into full play and realize unmanned operation. 3)To develop steel structure by using enterprise itself producing steel products, may adopt customized-made and use a large amounts of steel products produced by itself.

18 3.2.2 Raw material and fuel delivery system closure Raw material and fuel are widely conveyed by using belt transportation, for examples: mixed ore are conveyed to the sinter batching chamber by belt conveyor, the coke powder is transported from the blast furnace area to the fuel warehouse in the sintering area by means of a belt conveyor. The anthracite is transported from the raw material yard to the fuel warehouse in the sintering area by belt conveyor and then transported into the sinter batching chamber after coarse crushing and fine crushing, the blending ore beneath storehouse is fed into belt conveyor after batched with disc feeder and weighing belt conveyor.

19 3.2.3 Reaction and combustion model optimization The model is critically based on raw material composition, layer thickness, ignition speed and air volume control. The main contents include, 1) Reduce temperature, optimize ignition mode, improve ignition efficiency and shorten combustion time. 2) Adopt High efficiency burner to improve flame stiffness and penetration. 3) Realize the linkage between varied raw material sintering and air-blowing volume, and the linkage between sinter raw material sulfur content and flue gas desulfurization. 4) Optimize combustion control to reduce nitrogen oxide concentration.

20 3.2.4 Optimization and renovation of carriage structure The sintering process is carried out on carriage, but the carriage exists serious cracks and thermal deformation which lead to high air leakage rate. Solution technology routes: 1) Optimize burden distribution pattern, reduce leakage and increase air permeability. 2)Reduce heat breakage to reduce loss and dust production. 3)Seal the head part and add an air volume adjustment device to reduce dioxin emission. 4) Optimize the granulation method of finished sinter.

21 3.2.4 Optimization and renovation of carriage structure The mixture on the sintering machine is sintered with suction after ignition. The sintering process develops from top to bottom and continues until the end of sintering. The end grate bar and the flanked blind plate are fixed with heat-resistant bolts. The middle grate and heat insulation are linked by linear structure so as to make the grate bar swing freely. The heat insulation pad is clutched on the frame beam of carriage with inlaid structure, and the insulation pad is made of Ni-Cr alloy.

22 3.2.5 Increase the recovery of waste heat To optimize the heat collection system, heat exchange system and others of waste heat recovery system. To Increase flue gas temperature, increase waste heat recovery volume and reduce carbon emissions in production process.

23 3.3 Expected effect of overall optimization Can reduce the air leakage rate of sintering system,reduce sintering efficiency and raise unit area output of sintering machine. Can decrease non-organized dust emission, decrease the load of the desulfurization system, the emission concentration of nitrogen oxide and the emission concentration of dioxin. Can increase residual recovery volume, reduce carbon emission Volume. Can reduce equipment failure and maintenance which decreases labor intensity.

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