160t Converter of JSPL Steel and Iron Company in India1. Gas cleaning, ventilating and air-conditioning1.1 OutlineThe main process equipments of steel-making system are two converter of 160t, two ladle of 160t, two rail tank desulphurization stations, one furnace of 160tVD, and corresponding auxiliary facilities of public.The design set the corresponding gas cleaning and ventilation, air-conditioning facilities, according to the process requirement. In order to meet the technological requirements of production and human health, prevent environment pollution. Gas cleaning and ventilation, air-conditioning facilities mainly comprise:(1) Initial gas purifies and gas recovery system of converter(2) Second state gas purify of converter(3) Flue Gas Cleaning System of hot metal folding tank；(4) Gas cleaning system in desulphurization stations(5) Gas cleaning system in refining furnace (incl. flux and ferroalloy loading dust cleaning system)(6) Ventilating and air-conditioning in public facilities.1.2 First de-dusting and gas recovery system of converterIn first de-dusting and gas recovery system of converter, we design two programs, girth wet dust cleaning system and LT dry electricity dust cleaning system. V olume gas recovery >90m3(standard condition)1) The technical data of the converter(1) Nominal capacity 160t(2) The average refining cycle converter 45 min once(3) Maximum rate of carbon reduction 0.48%/min(4) Carbon content in molten iron 4.0-4.2%(5) Carbon content in molten steel 0.04-0.1%(6) Temperature of furnace gas ~1500℃(7) The original volume of furnace gas 97440m3/h(standard condition)(8) Concentration of dust ~120g/ m3(standard condition)2) Process of dust cleaning system (wet dust cleaning program)The temperature of initial waste gas will go down to 900℃after passing through cooling flue. Gas goes into the spray scrubber through the swirling water seal, After going through the spray scrubber, dust over 5 microns in the gas will attach to the basic water spray, Under the action of gravity, integrated washing dust water settles at lowest place in the bottom of the tower and reaches circulating water treatment station through a water seal device, the pipeline and turbid water tankThrough the spray scrubber, the temperature of gas will decrease from 900℃to saturation temperature 75℃, efficiency of dust collection reach 97%. The saturate gas will enter annular gap scrubber through connecting pipe.The annual tap scrubber provides adjustable girth throat, the micro-pressure difference inside and outside the mouth can translate in the electric signal by the differential pressure transmitter. Led by adjusting the hydraulic actuator unitaction, drive within the venturi tube up and down movement within the cone, the temperature of waste gas in annual tap decrease 7℃, and the outlet temperature is 68℃.The annual tap scrubber is dual throat, and work flow rate stabilized at 80-100m / s. the minimum design velocity is 60m/s, while the maximum design flow rate is 120m/s, diameter of droplets is between twenty-five and seventy microns, dust removal efficiency can reach 98 ~ 99.9%.After treatment, concentration of flue gas emission will be <50mg/m3 (standard conditions).After air with water droplets enters the 90o bend evaporator, due to the subject of inertia and centrifugal effect, Water droplets left behind to the vane of evaporator and wall of the device and shed along the wall, at the lowest point through the pipeline, water seal device and drainage trap ,the droplets reach the circulating water tank station.In order to achieve better dewatering effect, behind the 90o bend evaporator the re-establishment of a cyclone evaporator is installed to further separated droplets from the flue gas. Water droplets under the action of centrifugal force is separated and collected in the inner wall of the container. After collecting the water at the bottom of the lowest point in the cone, it will reach circulating water tank station through pipeline, water seal and drainage trap.Fan of waste gas cleaning system is double support, double inlet, single outlet turbine gas blowers with automatic spray cleaning impeller wash system.The air flow of the fan is 210000 m3/h, the pressure is between 23000Pa and 26000Pa.The equipped motor adopt frequency control to achieve energy saving. After the fan, we equipped a coal gas converter station, a emergency relief valve, a water seal check valve and a V-shaped water seal.In the system Micro-elements oxygen and CO continuous automatic analyzers are provided and chain with switching station, in order that coal gas recovery and elution convert automatically. When the gas recovery condition meets, convert the valve to recovery state, at that time the converter gas transports to gas tank through the water seal check valve; when the condition is not satisfied, convert the valve to elution state, the converter gas exhausts by the sixty meters high chimney, while the ignition of the coke oven gas electromagnetic valve opens, the ignition device ignite oven gas burner automatically, so the coal gas drain from the chimney get burned. Two minutes later, the ignition of the coke oven gas electromagnetic valve closes automatically. When the switching station convert to recovery state again, the steam automatic purge device in the bottom of bleeding chimney startup, and shut down automatically after a purge of about two minutes.Upstream of gas switching station, a bypass valve is installed. If the switching station failures, the bypass valve opens, converter gas will diffuse through bleeding chimney.The system equipped with online temperature, pressure, vibration testing and control systems, controlled by PLC, which has man-machine interface.The main equipments（each converter set up a gas purification system, each setof system shows as follows）:(1) Spray scrubber one set(2) Annual tap scrubber one set(3) 90o bend evaporator one set(4) Cyclone evaporator one set(5) Coal gas evaporator one set(6) Water seal check valve one set(7)V-shape water valve one set(8) Gas blower one set(9) Riot Frequency conversion motor one set(10) Overflow water sealing holder three sets(11) Maintenance crane of 20t one set 3).Process of de-dusting system (dry de-dusting program)For first gas purification and recovery system, each converter sets up one set (the following description is written for one set). Converter gas purification and gas recovery system uses the LT dry program for cleaning and recycling. The furnace gas mix with a small amount of air at hood mouth, burning coefficient α = 10%, after cooled by the cooling flue, it comes into the purification and recovery system. The LT dry program device mainly comprises gas cooling system, gas purifying and ash conveying system, Safety control system and other ancillary equipment. The purification equipment mainly consists of four electric field round ESP, flue gas dust content after purification was less than 15mg/m3(standard conditions).The main function for equipments of first gas purification and recovery system is showed as follows (each converter sets up a gas purification and recovery system, the following description is written for one set):(1) Evaporative coolerEvaporative cooler is direct cooling gas equipment, which a double nozzle medium spray is set at the top of the cooler for fine spray of water; the amount of water is adjusted according to the hot air exhaust enthalpy. After the procedure, temperature of waste gas will go down to 180℃, and dust concentration of waste gas decreases about 40%(2) Dry electrostatic precipitatorAfter cooled by evaporator cooler, the converter waste gas enters dry electrostatic precipitator. In order that the dry electrostatic precipitator has better explosion-proof ability and aerodynamic characteristics, its shell is designed to cylindrical, in the case of converter gas explosion, in order to ensure safety of equipment, there are four scalable explosion venting and automatic reset of the safety valve in the electrostatic precipitator inlet and outlet of the cone parts. Four dry electrostatic precipitators ensure that gas dust concentration can be less than 20mg/m3 (standard condition) after treating by dry electrostatic precipitator with four fields.Process Design of the Electric Dust Catcher of Converter Gas SystemThe dust content in the converter gas coming out of gas holder will be as highas ～l00mg/m3, which can not used in the steel making and rolling system. In order to meet the requirement of consumers, purification will be designed for converter gas to reduce the dust content to l0mg/m3 or below.The maximum delivery flow of the converter gas recovery system is ～43000m3/h, so two 60000 m3/h plate-type electric dust catchers will be designed.The electric dust catchers will be located between gas holder outlet and booster,i.e. the converter gas coming out of gas holder will be sent to electric dust catchersthroughΦ1620x8. Before entering electric dust catchers, the converter gas should pass DN1600 butterfly valve and goggle valve. Converter gas purified in the electric dust catchers will go through goggle valve and electric butterfly valve before entering boosting system.Control of the electric dust catchers will be realized through computers installed in control room. In order to clean electric dust catchers, continuous and intermittent water spray system will be designed for the electric dust catchers.In order to achieve automatic control of the electric dust catchers, automatic process detection system will be provided to provide such control functions as spark frequency tracking, peak valve tracking, intermittent discharge and etc., so as to adjust production process intermittently, hence to optimize the working condition of equipment.In order to assure safe operation of electric dust catchers, micro-oxygen analyzer will be mounted on the gas pipeline before electric dust catchers to give alarm in case of too high oxygen content in converter gas, in which case the high-voltage power supply of electric dust catchers will be cut off automatically.Meanwhile, the valves on the inlet piping of electric dust catchers will be closed and valves of by-pass will open, so that converter gas can enter boosting system through the by-pass. Self-enclosed relief valve will be mounted on the proper of electric dust catcher to assure safe operation.(3).Fans and motorBecause the resistance of electrostatic precipitator is small, purification system using axial flow fan, whose motor apply frequency conversion control, and it will greatly reduce power consumption, lower production costs.（4）Boosting Station of Converter GasThe converter gas coming out of gas holder has a pressure of ～3.0kPa, which does not meet the requirement of consumers, so a boosting station will be designed.The main building of the boosting station will be a two-layer structure with two bays. The main production bay will have a span of 9.8m and the auxiliary bay will have a span of 6.0m. Three centrifugal blowers (two work, one standby) will be provided in the boosting station. Besides, one electric mono-rail bridge crane will be designed in the boosting station. The auxiliary bay is mainly for control room, power distribution room and living welfare facilities. Necessary movable firefighting facilities will be provided in power supply and distribution room.Main technical parameters of converter gas boosters:- Type: centrifugal blowers- Inlet flow: 600m3/min- Pressure rise: 19~21kPa- Motor power: 400kWNitrogen is mainly used for the purging of gas holder, boosters, electric dust catchers and pipelines. The maximum consumption of nitrogen will be 20OOm3/h and the pressure of it will be approximately 0.4MPa. Nitrogen will be used intermittently.(5) Gas saturatorIn order to reduce the gas tank capacity, improve the quality of converter gas, the gas saturator is set up between the switching devices and gas tank, so that the converter gas temperature drops to 70℃.The main equipments data of first waste gas cleaning system and gas recovery system :( the following data is for one converter)(1) Evaporator cooler (domestic manufacturing and technology abroad) one set(2) Electrostatic precipitators (critical spare parts are made abroad) one setDealing air flow: L=97440m3/h(standard conditions, dry air)(3) Coal gas blower (made abroad) one setAir flow: L=97440m3/h(standard conditions, dry air)Pressure: 8.5kPaCorresponding Frequency conversion motor: one setPower 850kW(4) Switching device :( introduced from abroad) one set(5) Pressure balance valve: (introduced from abroad) one set(6) Coal gas saturator: (domestic manufacturing and technology abroad) one set(7) Ignition device: (introduced from abroad) one set 4).safety and energy saving measure(1) Explosion-proof measuresIn order to ensure production safety, the relationship of the treatment between the explosion and the vent, we should first focus on the explosion, and eliminate all the conditions that may cause an explosion before the explosion.The low-temperature area downstream of evaporative cooling flue should avoid dead areas, and speed up gas flow rate as far as possible, to prevent the gas retention. Explosion-proof films are set up in all dead corners; explosion-proof seal are set up on related department of the system, so it can vent explosion in the event of an accident. For the locations that gas may leak, all ventilation equipment should be asked to consider in accordance with explosion-proof.(2) Speed control of gas blowerGas blower’s speed is controlled by frequency conversion motor, in order to achieve energy conservation. Motor speed is chain with the tilting converter. When the converter tilting to the tapping position, fan shift from high-speed to low speed; when the converter swing to charge hot metal, plus scrap, the furnace goes back to "zero" position, the fan operates at high-speed.(3) Continuous automatic analysis of gas composition and automatic control of gas switching stationsContinuous automatic analysis of gas composition at the outlet of the fan, when the gas recovery condition meets, open recovery of the gas switching station side automatically, and elution side closed. Otherwise, the gas ignition bleeds.The converter gas recovery condition:(a)CO≥35%，O2≤2%；(b) Oxygen blowing under oxygen lance(c) Blower operates at high speed(d) Coal gas tank is not at high position(e) Temperature of blower is below 80℃(f) When the activities hoods down, differential pressure devices operate naturally.(g) Pressure of condensed air is normal in coal switching station（5）Coal gas switching station chain with fume exhausting stack and ignition device When converter gas shift from exhausting state to recovery state, recovery side of switching station opens, at that time, steam purge valve opens, to sweep on the elution chimney and the ignition flame.2) Secondary de-dusting System of ConvertersSecondary de-dusting system of converters mainly collect the dust gas generated by the hot metal in the converter, plus scrap steel, the steel tapping, spray lining up and the process of flue gas and dust gas escaping from converter smelting process.Two converters are combined to set a secondary flue gas de-dusting system, which is designed as variable air volume systems, the total air volume system is 1000000m3/h.A dust extraction facility formed by dust extraction hood and enclosure hood at charging side of the converer, dust extraction duct at the tapping side of converter is provided. At the dust extraction duct, motorized valve is installed and chain with the process operation. When the converter is feeding, smelting, the motorized valve before the converter at the dust duct opens, and the motorized valve after the converter at the dust duct closes. When the converter is tapping, the motorized valve before the converter at the dust duct closes, and the motorized valve after the converter at the dust duct opens. When the converter is feeding, tapping, the hot gas carrying large amounts of dust will rise, and it will be arrested into the dust collection system immediately; when the converter is smelting, the secondary dust gas escape from the mouth will be tapped by blast furnace flue dust cover.The equipment of de-dusting system is centrally controlled by the control system installed in the operation room near the bag filter. The control of bag filter itself, dust transferring system, de-dusting fan and motor, butterfly valve at the de-dusting duct are all integrated into PLC. The running status of the butterfly valves is centrally monitored in the electrical room and the fault signal will be transmitted to the operation room of the de-dusting system in an optic way or by telephone. The bag filter, dust transferring equipment and de-dusting fan are arranged in open air. The collect dust will be transferred by the Client to the raw material stockyard by trucks, and utilized integrated. There is a silencer at exit of the fan.The main equipments of de-dusting system include:(1) De-duster: low pressure long bag pulse de-dusterQuantity: 1Filter area: 13500 m2Capacity: 800000m3/hDust content at outlet: <30mg/m3(normal condition)(2) ID fan:Quantity: 1Capacity: 800000m3/hPressure: 5100Pa(3) Motor (2000kW) 1 set 11kW(4) Speed regulation hydro-coupling: 1 set(5) Dust transferring system: 1 setDust silo: 1setDust wetting device: 1 set(6) Silencer: 1 set1.3 De-dusting System of hot metal folding tankHot metal will produce huge of dust gas when the gas tank off, in order to improve the steel work environment, especially the work of the regional workshop, ensure human health requirements, a pot of hot metal Flue Gas Cleaning System is provided. Total system design air volume is 1000000m3 / h.Equipments of this de-dusting system’s choose is the same as secondary gas cleaning system.1.4 Gas cleaning system of desulphurization stationA gas cleaning system is set for two desulphurization stations, and total system design air volume is 1000000m3 / h.Equipments of this de-dusting system’s choose is the same as secondary gas cleaning system.1.5 LF ladle refining furnace and flue gas de-dusting system of feeding ferroalloysA de-dusting system is provided for two ladles refining furnaces and feeding system. At the water-cooled furnace cover of ladle refining furnace an extraction duct is set, and movable air draft devices are put to use for feeding discharge car. Sealed covers are set at the discharge and feeding conveyor points, motorized valve at the branch de-dusting duct is installed and chain with the process operation, total design air volume of the system is 800000m3/h.All the equipments of gas cleaning system use central control. The control system installs in the operation room near the de-duster. The control of the de-duster itself, dust transferring system, butterfly valve at the de-dusting duct is all integrated into PLC. The running status of the butterfly valves is centrally monitored in the electrical room and the fault signal will be transmitted to the operation room of the de-dusting system in an optic way or by telephone.De-duster, dust transferring devices and fans are open layout; there is a silencer at exit of the fan.(1) De-duster: low pressure long bag pulse de-dusterQuantity: 1Filter area: 11000 m2Capacity: 800000m3/hDust content at outlet: <30mg/m3(normal condition)(2) ID fan:Quantity: 1Capacity: 800000m3/hPressure: 5100Pa(3) Motor (2000kW) 1 set 11kW(4) Speed regulation hydro-coupling: 1 set(5) Dust transferring system: 1 setDust silo: 1setDust wetting device: 1 set(6) Silencer: 1 set1.6 Ventilation and air conditioning systemThe auxiliaries include main control building of steel making, main control building of continuous casting, hydraulic stations, control rooms, operation rooms and electric rooms of shops and water treatment systems as well as other auxiliaries. According to process requirement, axial fans will be selected for ventilation and air conditioning will be designed wherever necessary, so as to meet the humidity and temperature requirement of different rooms.1) Ventilation facilities(1) At the operating point where high-temperature operation of the plant and oxygen gun platform maintenance work, because of the molten steel radiation heat or heat dissipation, the condition is bad, in order to improve the working condition of high-temperature working area, movable ventilation facilities will be designed.(2) For continuous casting posts, the temperature is high in summer. Cold air produced by air conditioners will be provided in summer to improve the working condition.(3) Ventilation of auxiliariesCommon or explosion-proof axial fans will be designed for water treatment facilities, water pump stations, dosing rooms, lab facilities, de-dusting fan rooms, electric room and hydraulic stations, etc.For oil lubrication station, low-voltage distribution room, transformer room and etc, T35-11 axial fans will be designed according to the practical requirement of different room, so as to meet the indoor temperature requirement of different rooms.2) Air conditioning devicesAccording to process requirement, water-cooled or air-cooled air conditioning facilities will be provided in the main control buildings of converters and continuous casting, operation rooms, instrument room, computer room, MCC control rooms and duty rooms, etc., so as to meet the temperature and humidity requirement of different rooms.2．Waste Gas Cooling System2.1 Water cooled flue of converterTwo 160 t converters will be built in this project, each converter will be equipped with one set of water cooled flue to cool down high temperature flume and recover gas.2.2 Composition and characteristics of water cooled flue system of converterThe converter flue is cooled by closed loop circulation soft water. Soft water of ~68℃ passes through the air cooler flows to water inlet pipe by hot water circulation pump and then enter the flue. After heated in the water cooled flue, the hot water is collected to the expansion water tank through the riser at ~88℃ from where it flows through the down comer to the air cooler while being cooled for recycling.Water in the system will expanded while heated, so expansion water tank is used to compensate such volume expansion. To prevent high temperature water from becoming steam which will affect system operation, nitrogen is used for boosting at the water surface of the expansion tank and the nitrogen pressure is kept between 0.15 and 0.4MPa, which is higher than the saturated pressure of the water in order to make the whole system always kept at saturated status.The quality of closed loop circulation water is reliable since it does not contact with atmosphere air. However such kind of system has complicated design, high equipment cost, large occupied area and heat recovery is difficult.2.3 Data of the system design(1) Operation condition of converterNominal capacity of converter x number: 160t×2Ave. tapping amount of converter: 160t/heatHot metal charging amount: ave. 146t/heat; max. 170t/heatCarbon content in HM: ~4.2%Carbon content in liquid steel: ~0.1%Number of converters always blowing: 2Blowing time: 15min/heatTap to tap time: common carbon steel: 36min/heatOxygen supply intensity: 3.85m3 (standard condition)/min.tMax. carbon dropping speed: 0.48%/min(2) Characteristics of converter waste gasGas output (recovery stage): ～120000m3 (standard condition)/hGas temperature: ～1500℃Gas analysis: CO 86%; CO2 10%;O2 0.5%; N2 2.8%Dust content in converter gas: ～120g/m3 (standard condition)(3) Condition of waste gasCombustion ratio inside hood: 10%Output: ～150000m3 (nominal condition)/hExhausting temperature: 900℃2.4 Circulation systemWater cooled flue of converter consists of skirt, fixed hood, main flue and tail flue which are cooled by LP forced circulation water system.Running data of the systemWorking pressure: 0.2～0.4MPaWorking temperature: 68～88℃Main process flow of closed loop water cooling system:68℃soft water→ hot water circulation pump→ water cooled flue of converter →88℃ soft water→ expansion tank→ air cooler →68℃ soft water.2.5 Specification and characteristics of main water cooled flue equipmentThe proper of water cooled flue includes five parts: movable skirt, horizontally shift hood, main flue section I, main flue section II and tail flue.(1) Movable skirtMovable skirt is formed by φ51×5 seamless steel tubes coiled into a taper. Round bar is packed between each layer of coiled pipes on the inner surface of the movable skirt to constitute a welded air sealed structure for forming a smooth inner surface and preventing slagging.The upper part of movable skirt is φ4200mm and the lower part φ5391mm preliminarily. The skirt is about 1090mm high, the heating surface is ～15m2, and the metal is 4.5t. It can be lifted up and down freely by means of lifting device which is hydraulically driven and moves at 800mm stroke.(2) Horizontal shift hoodHorizontal shift hood is above the skirt. During maintenance of converter, the Horizontal shift hood must shift out to provide the space required. The horizontal shift hood is of cylindrical tube and plate design with heating tube bundle arranged longitudinally. Pipe and plate are air-tight welded to form a diaphragm water cooling stave. The heating surface consists of 216 pieces of φ38×5 seamless tube. The fixed hood is about 23 t and φ3200mm, of which the heating area about 105m2.In the horizontal shift hood, oxygen lance hole and charging hole are opened which are equipped with corresponding lance dome and charging chute dome cooled by LV forced circulation evaporation cooling system.(3) Lifting system of movable hoodDrive type: Hydraulic driveQuantity of hydraulic cylinder: 4Stroke of movable hood: ~800mmThe lifting mechanism of movable hood is driven by four water cooled hydraulic cylinders.(4) Traversing bogie of movable hoodSpan: ~5500mmQuantity of lifting hydraulic cylinder: 4Operating mode: Manual controlLifting stroke: 700mmTraveling motor power: 37kWTraveling speed: ~5m/minWhen skirt is separated from movable hood, the weight of skirt and movable hood is taken by bogie. The skirt is lifted or lowered by four separate hydraulic cylinders. The manual plunger pump and oil tank of hydraulic system are both arranged on bogie. Platform is arranged around skirt. Steel plate is provided on platform. Allweight of bogie is taken by the two rail beams. The four traveling devices are provided with anti-friction bearings. The bogie is driven by motor.(5) Main flue section IThe main flue section I is also of cylindrical tube and plate design with heating tube bundle arranged longitudinally to form a diaphragm water cooling stave. The heating surface consists of 216 pieces of φ38×5 seamless tube. This section of flue is about 25t and φ3200mm, of which the heating area about 155m2.The included angle of the lower inclined part of the main flue with horizontal plane is 55︒.(6) Main flue section IIThe cross section structure of main flue section II is the same as that of section I, the flue is about 20 t and φ3200mm arranged with 196 tubes all around, its heat transmission area is about 130m2.(7) Tail flueThe structure and diameter of the tail flue are the same as the main flue. The waste gas flows horizontally from the top of the main flue to the tail flue and turns 90︒before entering vertically downward to the gas cleaning device. The heat transmission area is about 75m2. and the tail flue is about 12 t totally.(8) Expansion tankInner diameter: φ2800mm, length of cylindrical section: 10.5m, total volume: 71 m3.(9) Expansion tank (blowing down periodically)2 sets with volume of 7.5m3 and P=0.15MPa.(10) Dosing deviceOne combined type dosing device is provided, at its base, two 1m3 chemical tanks and three plunger type dosing pumps (two working and one standby) with flow of Q=50L/h and lift of H=6.3MPa are installed.。