In recent years, China's ceramic industry has developed rapidly. China's daily production of ceramics, building sanitary ceramics are ranked first in the world, of which daily production of ceramics up to 17 billion, accounting for about 65% of the world's total output; building ceramic tile annual output of about 3.5 billion - Accounting for 55% of the world's total output. At the same time China is also a large energy consumption, construction and sanitary ceramics industry is fuel consumption and power consumption. At present, China's ceramic industry's energy efficiency is only 28% to 30%, and developed countries 50% to 57% of the energy utilization gap is still relatively large.

    Spray dry milling is one of the ceramic industry's high energy consumption production processes. According to the ceramic energy audit data show that the energy consumption of spray drying and milling accounted for 10 to 20% of the total energy consumption of ceramic plants. With the energy crisis and the fierce competition in the market, reduce the energy consumption of spray drying and milling, to reduce the production cost, improve the competitiveness of enterprises and promote the sustainable development of ceramic industry has far-reaching and important significance.

Main measures of energy saving and consumption reduction in spray drying tower

As the energy consumption in the process of spray drying directly affects the economic efficiency and development prospects of the enterprise, the ceramic enterprises and industry experts have put forward a lot of measures to reduce the energy saving and consumption of the spray drying process. The main aspects are as follows: Spray drying tower itself performance structure and other aspects of the adjustment; the other is the nature of dry matter control, fuel problems, the nature of dry media and other factors.

Dry media control

Improve the hot air into the tower temperature

     In the constant temperature of the tower under the conditions of the hot air into the tower temperature (also known as the inlet temperature) the higher the total heat into the higher, the unit mass of hot air to the mud droplets to the more heat, the unit hot air The more water is evaporated. In the case of constant production capacity, the amount of hot air required to reduce (that is, to reduce the heat from the tower when the heat away), reducing the heat consumption of spray drying powder, improve hot air utilization and thermal efficiency. But the hot air temperature into the tower can not be too high (not more than 600 ℃), the temperature is too high, it will burn the tower top fan.

Reduce the hot air out of the tower temperature

In the case of the hot air temperature of the tower, the lower the temperature of the hot air outlet tower, the greater the temperature difference between the inlet and the tower, the higher the heat energy that the hot air passes to the mud for drying, so the higher the hot air utilization rate. But the exhaust temperature can not be too low, less than 75 ℃ due to powder too wet, affecting the normal dry.

Out of the tower hot air (waste gas) recycling

After the ceramic mud is spray dried and pulverized, the heat of the tower will be discharged into the atmosphere, which will be very substantial (about 10% to 20% of the energy consumption of the milling process). So this part of the waste heat should be fully utilized, such as the tower can be hot air recycling to preheat drying process. In addition to the direct use of hot air tower, you can also use the heat exchanger on this part of the waste heat storage or exchange and then use.

Spray drying tower itself

Select the appropriate specifications

Most of the ceramic industry manufacturers use 4000 spray drying tower, some ceramic factory using 5000 and 6000, the largest SACMI developed 12000, up to 48 nozzles. The larger the model, the greater the production capacity, the production of energy per ton of powder is relatively small, manufacturers can choose according to the specific circumstances of the model.

Overall closed control

As the system uses negative pressure operation, if the air leakage will increase the energy consumption, so the equipment parts and connecting flange, hot air stove, hot air duct, exhaust pipe thermocouple jack, the tower on the negative pressure measurement hole , As well as the tower under the cone flap feeder discharge, whirlwind dust and other parts must be sealed, and can not leak.

Control of hot air stove

Hot air stove is the spray tower dry hot air source, its fuel consumption directly affects the level of drying costs, so it is a key part of the spray drying tower energy saving. The efficiency of the hot blast furnace depends mainly on the fuel atomizing nozzle. When the fuel atomization is uniform and the combustion is sufficient, the thermal efficiency is the highest, and the atomizing air pressure and the flow rate and the fuel pressure and the flow rate should be strictly controlled. In addition the atomization nozzle atomization angle, spray height, gun angle should be controlled in the appropriate range. The atomization angle (α) of the general atomizing nozzle is 90 ° ~ 120 ° and the spray height is 4 ~ 4.5 m. The gun angle is kept between 110 ° and 120 ° to ensure that the spray material and hot air can be fully Heat exchange. The choice of hot air furnace fuel can directly affect the cost of fuel consumption, such as cleaning with liquefied petroleum gas, light diesel oil will greatly increase the cost, with heavy oil, mixed oil must control its sulfur content, or exhaust gas is difficult to ensure SO2 Emissions standards. Now a lot of ceramic factory coal gas in the sorting out of coal mixed with coal ash (coal gas containing 20% to 20% of unburned carbon, and some up to 20%) of coal-water slurry, and the coal The production of phenol water and tar in the air into the hot air furnace combustion, can put an end to these harmful substances in the high temperature combustion will be harmless water and CO2 emissions. This will not only greatly reduce the cost of combustion, and can make full use of these waste, waste, energy saving.

Use of linear burners

The traditional spray drying tower hot air device generally uses fuel (gas) hot air stove, boiler steam heat exchanger, heat transfer oil heat exchanger or electric heating heating system. The traditional heating systems use heat exchangers, and the efficiency of the heat exchanger determines the efficiency of the traditional heating system of heat utilization; and heat exchanger life is limited, high maintenance costs. Linear burner as the core of the direct combustion hot air device. Linear burner size is relatively small, directly installed in the duct, the drying medium can be directly with the contact and quickly rose to the required temperature. Linear burner as the core of the direct-fired hot air device both energy-saving and environmental protection two characteristics. First, the linear burner combustion mechanism is reasonable, the combustion zone to maintain a certain amount of excess air, both to ensure complete combustion, but also inhibit the formation of nitrogen oxides. This direct-fired hot air device without direct heat exchanger and air contact to ensure that the combustion heat on the effective transmission of air, high thermal efficiency. In addition, the use of convenience is another feature of the linear burner, by adjusting the gas control valve to change the hot air temperature.

Mud quality control

1) to reduce the moisture content of ceramic mud, the heat required for drying less, but the low moisture content of the mud fluidity is not good, poor mobility of poor spray effect. To solve this contradiction, the production of usually add appropriate diluent (water reducing agent) or electrolyte (such as water glass, soda ash, humic acid, etc.) to adjust the fluidity of the mud, while reducing the moisture content of the mud. The author and the Guangdong New Pearl Group cooperation with the use of composite water reducing agent, mud moisture from 39. 5% to 36%, milling time reduced by 5 h, per ton of powder can save 16. 5 yuan, the output increased by 18. 8% , The annual cost savings of more than 150 million.

2) to improve the ceramic slurry temperature can effectively reduce the viscosity of the mud to improve the mud atomization performance, to prevent the mud from the slurry and clog the atomization nozzle. So you can use the tower hot air recovery of waste heat to preheat the mud, which is an effective way of energy recycling.

Conclusion

In addition to the above measures, but also in the energy to find a solution, such as the development and utilization of new energy, reasonable control of the combustion process. Of course, many problems need to be found in real production and resolved. Ceramic enterprises in the purpose of sustainable development to rationally improve and improve the energy efficiency of spray drying tower in order to improve the economic and social benefits of enterprises.