Requirements for energy saving, it prompted us to have to pay attention to the conservation of resources.
With the gradual implementation of the national environmental policy, the domestic refractory industry the original coal-fired furnace end of its historical mission, will be replaced by a clean natural gas, liquefied petroleum gas, light diesel oil, city gas, producer gas as the main energy of a new furnace. However, China is a major coal-producing country, refractories and high energy-hungry, production and production of low-grade refractory refractory enterprises or furnace hot gas as fuel to ensure fuel supply and production cost control . Thus, the refractory industry and the development of hot gas tunnel kiln, hot gas intermittently down draft kiln group, the hot gas intermittent shuttle kiln group.
Due to different the kiln body structure and thermal processes, the intermittent kiln than continuous production tunnel kiln flue gas from the kiln temperature by as much as five times higher. Generally, the higher the gas temperature, the greater the proportion of the heat loss. Such as gas temperature of 1093 ℃, the heat loss of 55%; when the gas temperature to 1427 ° C, the heat loss is as high as 70%. For hot gas fired refractory intermittent down draft kiln, according to experimental data show that the total calorie expenditure: flue gas from the kiln taken away by the sensible heat furnace accounts for about 35% to 40%, in the absence of any heat recovery measures in the case, the heat balance calculation, the thermal efficiency of only 10% to 15%. This is a great heat loss. Therefore, the use of flue gas heat is a very important energy recovery. 2 Process Description
Set in the flue heat exchanger is an important means of waste heat recovery. Was obtained in a hot-air through the heat exchanger can be directly supplied to the burner for combustion air, hot air dilution can also be conveyed to the article embryo drying kiln drying medium or it reaches 30% or higher, so that the thermal efficiency of the kiln.
When the firing system using preheated air and the combustion of the combustion air with the hot air can not only improve the thermal efficiency of the kiln, to reduce fuel consumption, and to achieve the energy saving effect of the heat exchanger. But also can improve the high-temperature combustion in the organization of the flame temperature, and increase the heating efficiency, shorten the heating time (firing cycle). Volume expansion of hot air, resulting in the burner jet exit velocity increases to accelerate the circulation of the gases in the kiln, to contribute to a uniform temperature of the kiln. The data indicate that: when the preheated air temperature reaches 220 to 250 ° C, can reduce fuel consumption by 6% to 8%. Different combustion air temperature, the flame temperature is very large. Even in the case of gas is not preheated, the temperature of the combustion gas with the combustion air preheat temperature increases significantly improved. This can not only solve the problem of low firing temperature, plays an important role for enterprises to save energy.
In the intermittent kiln production, since the fuel is changed with the heating stage, the amount of flue gas produced by the fuel change, the need to fire the stage, due to the increase of the quantity of fuel of the unit time, and the resulting flue gas and the temperature must also increase, preheating combustion air good adaptation combustion requirements. More commonly used in the production of metal tubular heat exchanger, due to high temperature oxidation and mechanical properties of the restrictions, the maximum temperature is generally limited to below 500 ° C, because of its low life (0.5 years). The metal pipe aluminizing treatment, its service life is only about a year. Heat-resistant stainless steel or heat-resistant cast iron, the maximum temperature is generally limited to below 900 ℃. But because of its expensive, and use unbearable. Lun Ji Technology Development Co., Ltd. Beijing development and design of the horizontal flue ceramic heat exchanger, is clayey, good corrosion resistance, even if the flue gas temperatures up to 1300 ° C can work safely and reliably, as shown in Figure 1. Fuel furnace gas, flue checker bricks will not be blocked. The useful life of more than 10 years. Designed to ensure the efficiency of heat transfer, heat transfer area as large as possible that the square down draft kiln heat transfer area (such as a set of 4 × 200m3 230m2), the volume is ambitious, but the on-site conditions allow, a one-time investment, flue system resistance is generally about 147 to 196Pa, pursuant to select the height of the chimney (usually around 50m).
A new type of fuel can be recycled again active aging, is a good resource conservation.
