A kind of method that improves medium heat conductivity in curing furnace
The invention belongs to the curing oven field of metallurgy industry light plate, relate in particular to the production field of color coating line curing oven heat exchange.
The general heating, drying mode that adopts behind the Bus in Color Coat Production Line coating liquid paint vehicle, high-temperature gas is heated to predetermined temperature with band in the curing oven by supplying with, and make the solvent heating evaporation, with solidified coating, the energy that this process need consumption is a large amount of, present domestic Bus in Color Coat Production Line can be divided into direct-fired being heating and curing by the heating means of curing oven, the air indirect is solidified, waste gas circulation is heating and curing, mode advanced at present and the saving energy is two kinds of back, for example in the applying date be: what on June 6th, 2008, the patent No. was that 200810111550.5 color coating wire harmful gas concentrates waste gas of incineration utilization introduction is that the air indirect is solidified: extract rich solvent waste gas out and put the cleaved burning burning of the most solvents that contain toxic gas cracking the following waste gas of above hot conditions in cracking in curing oven, discharge a large amount of heat energy, consume the most of oxygen in the waste gas simultaneously, the high temperature inert that produces (reduce to about 5-8% by control excess oxygen content, relative inertness) flue gas, form the high-temperature low-oxygen flue gas, by heat exchanger heating fresh air, send into curing oven with the air after this being heated by air blast, steel band after the japanning is cured oven dry, another kind of mode is to be 200910078772.6 color-coating line paint curing oven security heating method at applying date 2009.3.3 application number, utilizing incinerator waste gas directly to mix circulated air as the heat carrier enters in the curing oven steel plate is heated, exhaust gas heat exchanger is housed behind the incinerator, sending into incinerator behind the heating by the exhaust gases that comes from curing oven, incinerator is equipped with the natural gas burner, and the waste gas that curing oven is sent here is heated to the cracking point to carry out cracking and burn.High-temperature flue gas behind the heat exchanger is sent to curing oven and mixes each section circulated air heating steel plate, simultaneously, the new solvent gas that produces in the dilution curing oven, the furnace gas that the air draft pipe of curing oven will contain solvent gas is sent to the exhaust gas heat exchanger of CIU, forms a systemic circulation and finishes the burning of waste gas and the circulation of heat.The heat exchange method of these two kinds of curing ovens all is the convective heat exchange that adopts, heat exchanges by convection type, the heat transfer coefficient of time and heat transfer medium is depended in the raising of steel billet temperature, and the time is meant the time that steel plate stops in curing oven, be directly proportional with furnace superintendent, and another key factor is exactly the heat transfer coefficient of medium.In the technical scheme that the air indirect is solidified, thermal medium is dry hot-air, and the coefficient of heat conduction of air is.In the technical scheme that waste gas circulation is heating and curing, it is as follows to burn reaction equation: C
2O produces 10000Nm in combustion process
3Waste gas in the content of aqueous vapor be 455.6kg, the relative humidity of waste gas only is 7.6X10
-5So it also is dry air basically, its thermal conductivity factor solidifies identical with indirect basically.The thermal conductivity factor of the curing furnace gas of these two kinds of technical schemes is all very low, and the energy that the heating steel plate needs is certain, and furnace superintendent is constant, and the heat conduction efficiency of medium is low, and required energy input is big, consumes a large amount of energy.
Summary of the invention
For the thermal conductivity factor that overcomes original curing furnace gas is low, the thermal energy consumption height, the deficiency that energy waste is big, the present invention adopts and add the way that atomized water steam improves the furnace gas heat transfer efficiency in furnace gas, cuts down the consumption of energy.
The technical scheme that the present invention solves its technical problem is: a kind of method that improves medium heat conductivity in curing furnace, check in the good conductor that three atomic gas are heat from handbook, water vapour is that occurring in nature content is abundant, three atomic gas materials of most economical material benefit, the waste gas that extracts in the curing oven is sent to main heat exchanger after waste gas combustion furnace burns cracking, improve the gas temperature that enters curing oven, it is characterized in that leading on the pipeline of curing oven, add atomized water steam at high-temperature gas.The amount that is to add atomized water steam is the 15-25% of furnace gas, the thermal conductivity factor of furnace gas will increase by 25%, the atomized water steam water source medium that adds is soft water or pure water, and atomization system is made of water source, stop valve water pump and the atomizer of soft water or pure water, the content of atomizing water vapour is measured by the dew point hygrometer in the curing oven in the curing oven, measured value and setting value compare, and input signal is given the electric control system controls water pump, thus the content of control atomized water steam.
The invention has the beneficial effects as follows: after in curing oven, adding the atomized water steam of furnace gas 15-25% content, gas is compared thermal conductivity factor with dry air will increase by 25%, increased thermal conductivity energy greatly, when steel plate requires the certain needed heat of solidification temperature constant, under the situation that does not change furnace superintendent, improve the coefficient of heat conduction of gas, will reduce needed energy consumption and will reduce greatly, reduce energy waste, provide cost savings.
Description of drawings
Among Fig. 1: indirect curing oven schematic diagram
Among Fig. 2: the required thermal source of color coating line indirect curing oven supply centre
Among Fig. 3: the waste gas circulation stove schematic diagram that is heating and curing
In Fig. 1: 1. change be coated with stove, 2. the rendering stove, 3. essence is coated with stove, 4. waste gas combustion furnace, 5. heat economizer, 6. first-class heat exchanger, 7. secondary heat exchanger, 8. degreasing, No. 9.3 hot-air blowings, No. 10.2 hot-air blowings, No. 11.1 hot-air blowings, 12. atomization systems
In Fig. 3: 1. the inlet isolation ward of curing oven, 2. circulating fan, 3. high temperature oxygen analyzer, 4. curing oven, 5. the outlet isolation ward of curing oven, 6. incinerator, 7. one-level exhaust gas heat exchanger, 8. secondary exhaust gas heat exchanger, 9. air heat exchanger, 10. hot-air blowing, be coated with drying oven 11. change, 12. flue gas water cycle heat exchange device, 13. rich solvent exhaust pipe, 14. oxygen pipeline, 15. the rich solvent exhaust pipe after the preheating, 16. oxygen deprivation tail gas pipeline, 17. the air pipe line after the heat exchange, 18. oxygen deprivation tail gas branch line, 19. outlet isolation ward pipeline, 20. oxygen analyzer behind the secondary exhaust gas heat exchanger, 21. atomization system
The specific embodiment:
In accompanying drawing 1: take out from rendering stove 2 by air-introduced machine, essence is coated with interior about the 250 ℃ waste gas of stove 3, and 5 preheatings reach and deliver to waste gas combustion furnace 4 after about 350-400 ℃ again and be heated to and produce a large amount of heat energy greater than 650-700 ℃ behind the cracking incineration temperature more than 733 ℃ through heat economizer, supply with rendering stove 2 by new wind with from swap out 420-450 ℃ hot-air of the first-class heat exchanger 6 of the curing oven tail gas that contains few waste gas, essence is coated with stove 3 heating, before first-class heat exchanger 6, add atomization system 12, water source by soft water or pure water, pipeline, stop valve, water pump constitutes, soft water and pure water are extracted out with water pump, be atomized into water vapour by atomizer, the content that adds atomized water steam is the 15-25% of furnace gas content, content is measured by the dew point hygrometer in the curing oven, measured value and setting value compare, input signal is given the electric control system controls water pump, thereby the content of control atomized water steam, the thermal conductivity factor that adds the furnace gas of water vapour will improve 25% than the furnace gas of drying, energy resource consumption will reduce greatly, the control of furnace temperature is realized by PID, at any time the heating load of adjusting each combustor changes the circulated air temperature, to adapt to rendering stove 2, the thermal energy consumption point that essence is coated with stove 3 provides the required energy.Secondary heat exchanger 7 is that about 400 ℃ flue gas will be taken from the equipment that the outdoor hot-air supplyization that newly is exchanged into about 200 ℃ is coated with stove 9, No. 2 hot-air blowings 10 of 1, No. 3 hot-air blowings and No. 1 hot-air blowing 11 by tubular heat exchanger, changes to be coated with stove 1 and the control of the hot-air blowing temperature heat butterfly valve control by separately combustor supply.Three grades of heat exchangers of degreasing section are that about about 300 ℃ hot-air is heated to the cleaning of finishing strip about 65 ℃ by tubular heat exchanger with pre-treatment degreaser and water lotion.At last will be lower than 180-200 ℃ flue gas and be discharged to outdoorly, finish whole burning and heating by the exhaust gases UTILIZATION OF VESIDUAL HEAT IN overall process by a high pressure positive blower.
Curing oven 4 waste gas that contains organic solvent is compiled through one-level exhaust gas heat exchanger 7, secondary exhaust gas heat exchanger 8, to improve its temperature by rich solvent exhaust pipe 13 again as shown in Figure 3, entering Burning Room 6 then burns in combustor with the premixed gas of natural gas and air, discharge a large amount of heat energy, generate carbon dioxide and water, produce the incineration tail gas of high temperature inert, detected by oxygen analyzer behind the secondary exhaust gas heat exchanger 20, control excess oxygen content is reduced to about 5%.Tail gas carries out heat exchange through one-level heating by the exhaust gases heat exchanger 7, secondary exhaust gas heat exchanger 8 with new wind.This oxygen deprivation tail gas is supplied with curing oven to the tail gas that burns cracking by circulating fan 2 the band steel is heated through oxygen deprivation tail gas pipeline 16, returns to curing oven entrance circular chamber by high temperature resistant pipeline.
The cracking tail gas of part high temperature absorbs one part heat by oxygen deprivation tail gas branch line 18 through flue gas water cycle heat exchange device 12 backs, supplies with the cleaning heating of degreasing section.The most of reuse of incineration tail gas is to curing oven wind mixed chamber, be sent at incineration tail gas on the pipeline of curing oven atomization system 21 is set, water source, pipeline, stop valve, water pump by soft water or pure water constitute, soft water and pure water are extracted out with water pump, be atomized into water vapour by atomizer, the content that adds atomized water steam is the 15-25% of furnace gas content, the content of atomizing water vapour is measured by the dew point hygrometer in the curing oven in the curing oven, measured value and setting value compare, input signal is given the electric control system controls water pump, thus the content of control atomized water steam.The thermal conductivity factor that adds the furnace gas of water vapour will improve 25% than the furnace gas of drying, and energy resource consumption will reduce by 25%,
The adjustment of control air output reaches the purpose of control furnace pressure and subregion circulating temperature, the unnecessary incineration tail gas that system produces owing to furnace pressure control and working conditions change, finally the high-temperature blower by flue gas water cycle heat exchange device 12, oxygen pipeline 14, outlet isolation ward pipeline 19 places is discharged in the atmosphere by chimney.Be used to control the fire door isolation ward and collect the gas of being extracted out by the inlet isolation ward 1 of curing oven, isolation ward forms little negative pressure, helps air seal, prevents that furnace gas is excessive in the workshop.