Pre-reacting Behavior Of Glass Batch And Glass Melting And Fining Mechanism

Recently, in order to solve the problem of increasingly nervous energy and atmospheric pollution, the single-line production of glass melting furnace has become larger and larger and the largest has reached1200t/d. However, at the same time, it has found few problems, such as the enlarged furnace weight and span put forward higher requirement of refractory and steel performance. Therefore, it has become more and more difficult to reduce energy consumption and emissions simply by expanding single-line to expand production scale. So developing a novel and advanced glass melting technology has maximal practical significance and value on progress and development of glass industry. The glass batch silicate kiln decomposition technology mentioned in this topic is whole or partly "split" the process of silicate formation from the conventional melting process of float glass. Glass batch would complete the carbonate decomposition process outside the furnace, and then enter the kiln in form of silicate under high temperature, so it would mandatory be melted.This work set Na2O-CaO-SiO2system flat glass as research object. The performance change of loose glass batch and compacted glass batch was investigated by universal testing machine, X-ray fluorescence spectrometer, thermal conductivity analyzer and Pressure Differential Scanning Calorimetry. The laws in silicate formation of granular glass batch in775-850℃was investigated by gravimetric analyzer tester, X-ray diffraction analyzer, ultra-high temperature contact angle measuring instrument, polarizing microscope and stereo microscope. The degree of reaction, the reaction rate constant and the activation energy were measured. The melting properties of loose glass batch, granulated glass-forming batch and sintered compacted glass batch were contrasted by measuring melting time, fining time, melting efficiency and melting area. Finally, the heat consumption and the thermal efficiency of the furnace during the glass forming process were calculated theoretically. The results were shown as follows:The weight loss of loose glass batch reached the largest at775-850℃, at this time, silicate formation reaction became dramatic. There were no characteristic diffraction peaks of crystalline silica be observed at1050℃. When glass batch was compressed from loose to a granular, the bulk density and thermal conductivity of batch were increased, and the volume porosity was decreased, meanwhile, the temperature of silicates forming followed towards lower temperatures. The unmelted solid particles and bubbles in high-temperature melting glass were reduced.In the procedure of granulated glass batch treated from room temperature to775-850℉, as the increasing of sodium carboxymethyl cellulose solution and sodium silicate solution concentration, the temperature of silicate reaction was reduced, the anti-crushing ability and the degree of reaction were increased. The cohesive force between samples was strong enough to bond together when a large amount of liquid phases was produced at850℃for lh. When glass batch was treated in a constant temperature of775-850℃, as the increasing of holding time and concentration of binder, the anti-crushing ability and the degree of reaction were increased, and the calculated activation energy was decreased. The melting time and fining time of granulated glass batch were less than that of loose glass batch. As the increasing of pretreatment temperature, the time for melting granulated glass batch was increased first and then decreased, however, the fining was gradually extended,As the smaller of silica particle size, the anti-crushing ability of sample treated at775-850℃was increased, the content of residual silica crystal was reduced, the silicate reaction activation was increased, the energy barrier which was needed to overcome was decreased. The melting time of the untreated granulated glass batch was shorter than that of loose glass batch, but longer than that of the treated compacted glass batch. In addition, with the increasing of silica, the melting time of loose glass batch and pellets at1350-1450℃were both extended.The heat consumption of loose glass batch in the process of glass formation, including the silicate forming heating, the glass forming heating, the heating when glass was heated to melting temperature, the heating when escaping gas was heated to melting temperature, moisture evaporation heating and the heating brought by glass batch, were calculated theoretically. The heat consumption of loose glass batch, the untreated granulated glass batch and sintered granulated glass batch had little difference. Only using the exhaust gas which came from regenerator to preheat granulated glass batch was not enough, because the energy was barely provided to partially or fully completed the process of silicate forming, so it needed extra added heating energy. The output of furnace was increased from1200.00t/d to2159.89t/d and the thermal efficiency of furnace was increased from40.00%to65.70%when using the glass batch silicate kiln decomposition technology.