A furnace structure
● intermittent kilns
Energy consumption, low yield , the exhaust gas temperature at 600 ℃ ~ 860 ℃.
Affect shuttle kiln temperature field uniformity of key factors:
① The new burner , such as: isothermal burner, pulse burner , high-speed burner .
② to adjust the layout of the burner ,
③ improve the placement of the code blank ,
④ reasonable layout flue ,
⑤ For the shuttle kiln , waste heat utilization ,
⑥ Select the appropriate temperature measurement points and control methods.
● Continuous furnaces
① tunnel kiln
Temperature, especially preheating zone ; kiln walls, kiln car heat storage capacity , high energy consumption 2400-12000 × 4.18kJ/kg products ; adopting some new technology energy consumption can be reduced to 1100-5200 × 4.18kJ/kg . Adoption of new technologies : no box naked burning , light insulation , lightweight kiln car . There key issues: reducing firing atmosphere detection and control
② roller kiln
● Lower power consumption : low as 200-300 × 4.18kJ/kg products ;
● yield : more than 220m long kiln , ceramic tile production 10000m2 / d or more ;
● reasonable control of atomization air pressure and combustion air volume
● reasonable adjustment exhaust fan , pumping hot air extraction volume
● reasonable set of baffle wall , retaining the fire board
● Extend the length of the flame burner or extended , " Fire into heart"
● In the structure, the whole kiln kiln built flat or full arch structural transformation of firing zone building arch structure, can effectively reduce the cross-sectional temperature .
Two insulation technology
● heavy firebrick : quality, heat capacity, thermal conductivity heat storage , thermal capacity, the kiln wall surface temperatures up to 300 ℃ ~ 400 ℃.
● lightweight insulation tiles,
● mullite brick,
● High Alumina Brick ,
● lightweight ceramic fiber , light weight , low thermal conductivity , lightweight material weighs only 1/ 6, the bulk density of the traditional brick 1/25 , heat storage capacity of only brick -type lining of 1/30 to 1/10 the kiln wall temperature dropped to 30 ℃ ~ 60 ℃. The use of lightweight ceramic fiber , lower quality than products and kiln furniture .
● fiber energy , 20.6% of the total energy consumption dropped to 9.02% , up 16.67% energy saving .
● fiber powder,
● chalking research,
● anti- chalking
● kiln wall structure more reasonable , better energy-saving effect .
Three firing technology
● using the new burner : isothermal burner, pulse burner , high-speed burner .
● Adjust the burner layout .
Four coating technology
● a wide range of coating technology , wherein the infrared radiation layer and multi- layer application in the furnace of concern .
● Infrared heating the coating process is simple , low cost, infrared emission rate with significant energy savings.
● Protect the kiln wall is not subject to chalking : the kiln off the dirty, fiber powder
● Increase the infrared radiation heat transfer and thermal efficiency : at high stage, its painted walls in the kiln refractory , material radiation rate of 0.7 liters 0.96 per square meter per hour energy 33087 × 4. 18kJ, while at low temperature phase coated HRC , the kiln wall emissivity from 0.7 to 0.97 liters per square meter per hour energy 4547kcal.
● avoid secondary drop dirty .
Five harmful gas generation mechanism
● ceramic kiln flue gas harmful components : NOx, SOx, CO, CO2, ROx dust
● NO formation mechanism :
① Thermal type NOx: nitrogen in the air is oxidized , primarily due to the flue gas temperature and oxygen concentration in the flue gas temperature of 15000 ℃ above , NOx increase exponentially .
② Fuel type NOx: N in the fuel is oxidized , and the N content in the fuel .
③ fast-type NOx: content of less than 5% in general , mainly in the fuel-rich flame section .
● SOx generation
① sulfate decomposition of the raw material body , such as: pyrite, sulfate oxidation.
② oxidation of sulfur in the fuel , such as: organic sulfur , pyrite, sulfate, etc. oxidation .
Six suppression technology
● Reduction : Selective catalytic reduction SCR, adding a reducing agent such as NH3 reduction in catalyst NOx, reduction rate of 90% ; selective non- catalytic reduction SNCR, adding a reducing agent such as NH3 under high temperature reducing NOx, reduction rate of 30 % -70 % . Easily cause secondary pollution , catalyst deactivation , corrosion of equipment .
● Plasma Technology : Plasma process flue gas NOx control technology is the core through a certain way in the flue gas to generate plasma , NOx and other polluting gases in the plasma zone is decomposed or oxidized. The cost of equipment is still in the experimental stage.
● microbiological method : a suitable carbon source, denitrification bacteria are applied in the case , the use of nitrogen as NOx , the NOx oxidation basic harmless N2, the denitrification bacteria growth and reproduction of its access , removal efficiency 99%. Anaerobic environment is difficult to guarantee .
● electrochemical method : the use of electronic as an intermediate oxidation or reduction NOx, removal rate of 90%. Process temperature is low , the electrolyte is not easy to transport . China Insulation Materials Network
● acid oxidation method : the use of strong oxidizing properties of acid treatment, NOx and SOx removal rate of 95 % or more.
● Microwave Technology :
① pyrolytic carbon ( or activated carbon ) is both an excellent radio frequency energy absorbers, but also a good performance of the reducing agent. When the activated carbon is placed in the radio frequency energy field , the gas phase of the SO2, NOx and RF energy field in contact with the coke , carbon can quickly capture these oxides in oxygen than the speed of which is deprived of oxygen there is no RF fields exist faster.
② process is simple, high treatment efficiency , no secondary pollution , small investment , installation is simple , low energy consumption .
● multifunctional coating removal NOx:
① in the sunlight and ultraviolet light on the multifunction coating irradiation , NOx photocatalytic degradation rate of up to 55%.
② In the beginning of the reaction , NOx soon degradation rate reached 50 % or more , 6h after little change , to the saturation value of 80 % or so.
③ When the NOx flow rate of 0.1L/min, a contact time of the reactants the NOx degradation rate 76.3s maximum , 40.2 % or more.
④ The coated glass plate light catalytic coating placed outdoors , every 10 days, washed with water 1, test 1 month degradation effect on NOx results show that , in the outdoor for 6 months after the coating on the oxidative degradation of the NOx little effect reduction , decrease only about 2% 3% , the coating appearance change.
Seven microwave-assisted sintering technique
● microwave and conventional sintering firing difference.
● Microwave-assisted gas fired technology (MAGF) is a more practical and reasonable environmentally clean burning technologies.
● completely avoided by microwave sintering techniques produce CO, CO2, SO2 and NOx emissions, such as thermal efficiency ? Gou Yun- chu line and Aye Aye Farmer bear ?
● In China, the microwave sintering technology in high-performance ceramics and porcelain firing has been tried , but in daily-use ceramics , architectural ceramics is still blank .
● In other countries, such MAGF technology has been successfully in a variety of refractory materials , ceramics and sanitary ceramics firing has been applied and from the laboratory stage to the small-scale production .
● According to foreign sources, using MAGF firing technology can yield four times , saving more than 70% , down 40% in energy costs , the amount of harmful substances evaporate a significant reduction in the mechanical properties also improved.
Eight measurement and control technology
● Fuzzy Control :
Advantages : For the nonlinear ceramic kiln , it is difficult to model regarded as a good control object control method .
Disadvantages : The control accuracy is not high , adaptive capacity is limited , there is a steady-state error , it may cause oscillation , the lack of effective learning mechanism .
● Single point of fuzzy control : control object is usually the furnace temperature , the ceramic kiln firing process control characteristics under the influence , resulting in the design of fuzzy control rules inappropriate or incomplete affect its control effect.
● Multivariable Fuzzy Control:
① For having a diverse, random , continuous , highly uncertain and other characteristics of the control object , to a multi-level , multi-objective integrated results. China Insulation Materials Network
② core technology : soft embedded multivariable model-free self-learning fuzzy controller.
● sectional flow control :
① In the preheating chamber with the specific position of the lower kiln burner installation of certain speed , increase the agitation of the upper and lower air flow , reducing the cross section of the upper and lower temperature .
② in the firing zone and cooling zone of the kiln a distance from the top of each set hanging refractory fiber " barrier ."
③ In the top of the kiln burning zone and the burned products between the upper edge of the upper burner reasonable choice of the best locations.
④ In the cooling zone , the top and bottom products, a plurality of discharge air into the drum to quench with cold or hot temperature .
⑤ kiln for a wide cross-section should be appropriate to extend the length of the flame , avoiding cross-section of the hump temperature distribution .
Nine computer simulation technology
● entity model : Water model , the flame model , the aerodynamic model
● FLUENT software values:
① simulated wood kiln convective heat transfer process ,
② simulated roller kiln burner layout perspective on the impact of the flow field inside the kiln ,
③ Analog shuttle kiln flow field, convection heat transfer coefficient on the law and uniformity of kiln heat exchanger ,
④ Analog ceramic firing process the various factors affecting NOx formation .
Ceramic kiln direction of development :
● in the kiln structure, the continuous development of the longitudinal direction of the furnace ,
● In the kiln , kiln furniture materials , use of lightweight ceramic fiber ,
● the use of coating materials, save energy and reduce the emission of pollutants ,
● In the firing technology , the high temperature uniformity , low pollution direction, such as microwave sintering technology,
● In the detection method , using multivariable control technology,
● the research method , the thermal furnace combined theoretical and computational fluid dynamics ,
● green ceramic kilns kiln workers is the task of the new century