[China Glass Network] According to the Kyoto Protocol passed in 1997, in order to solve the problem of climate warming, the average greenhouse gas emissions of developed countries from 2008 to 2012 decreased by 5.2% compared with the 1990 level. Although the Kyoto Protocol does not stipulate the tasks of developing countries, the greenhouse gas emissions of developing countries are growing rapidly, and the pressure on developing countries to undertake emission reduction tasks is increasing. The Kyoto Protocol allows for “emissions trading”: countries with excessive emissions can buy “consumption” of greenhouse gas indicators from countries with insufficient emissions. Therefore, China and other major greenhouse gas emission countries are facing tremendous pressure, and it is very necessary to develop various energy conservation and emission reduction technologies.

1. Oxygen-enriched combustion and oxy-combustion technology

The basic principle of oxy-fuel combustion and oxy-combustion technology is to increase the oxygen content in the combustion air to fully burn the fuel. The second technology can reduce the nitrogen content in the glass melting furnace, thereby reducing heat loss, environmental pollution and equipment erosion caused by nitrogen and its reactants, thereby improving economic and social benefits.

1.1, oxyfuel combustion technology

Oxygen-enriched combustion artificially increases the amount of oxygen in the combustion air to increase the burning rate and reduce the amount of smoke. This technology is suitable for use in heavy oil-fueled furnaces because the combustion of heavy oil is first mixed with combustion air, and the slower mixing speed of the oil mist and air affects the burning rate. Increasing the amount of oxygen in the combustion air can increase the burning rate of the heavy oil, thereby increasing the combustion temperature. Oxygen-enriched combustion technology is particularly suitable for use in float furnaces. By-products of nitrogen (the main component of tin bath protection gas) are prepared by air separation in a float kiln. An oxygen-rich gas can be used as an oxygen-rich gas source for oxygen-rich combustion. . In the application of oxyfuel combustion technology, there are two main problems: First, the choice of oxygen-rich concentration, the higher the oxygen concentration of oxygen in theory, the better the fuel is fully burned, the energy-saving effect and the higher the combustion temperature, but in fact The relationship between energy saving rate and oxygen-rich gas purity is non-linear. When the purity exceeds 30%, the energy saving rate is not improved. At the same time, the high oxygen concentration will increase the cost of oxygen enrichment, so the actual cost of preparing oxygen-rich gas Considering the oxygen-rich concentration in the unit consumption, it is generally controlled at about 30%: the second is the configuration of the spray gun and the oxygen-enriched gas nozzle. Generally, there are three methods for enriching oxygen into the kiln:

(l) as a fuel atomizing agent;

(2) the oxygen-enriched nozzle is blown at a certain angle with the fuel nozzle;

(3) Inject oxygen enrichment in parallel under the fuel burner.

From the requirements of the combustion state of the fuel in the glass melting furnace: the upper part of the flame is an anoxic zone, the middle part is an ordinary combustion zone, and the lower part is formed as a high temperature zone to strengthen the melting of the batch material, to form this ideal combustion state, in the oil burning It is appropriate to blow oxygen-enriched gas in parallel below the nozzle.

1.2, oxyfuel combustion technology

The high-purity oxygen is used as the fuel atomization medium or mixed with the gas in the spray gun. The fully atomized or mixed fuel-oxygen is sprayed into the glass melting furnace by the spray gun to form a combustion flame, also called "fuel-oxygen" combustion. Compared with the conventional combustion air flame melting furnace, the oxy-combustion melting furnace does not require a high-heat accumulator device, so the investment cost of the melting furnace is greatly reduced. Secondly, the use of oxygen to assist combustion eliminates the problem of nitrogen taking away heat, which improves the heat efficiency, and does not produce nitrogen oxides (NOx) in production, and achieves environmental protection and emission reduction while saving energy. After using the total oxygen technology, the combustion gas is greatly reduced. The concentration of NaOH in the soda lime glass kiln gas is increased by 2 times; the HBO2 in the borosilicate glass kiln is increased by 3 times; the PbO in the lead glass kiln gas of the picture tube is increased by 2.5 times; the picture tube is lead-free. The KOH concentration in the glass kiln gas is also doubled; but at the same time, the water vapor concentration harmful to SiO2 is also increased by a factor of three. In this way, many SiO2-containing refractories in the upper part of the kiln are severely eroded. For example, the lifespan of silica bricks has been reduced from 10 years to about 2 years, which has constrained the development of oxy-fuel combustion technology.

2, new melting

A series of new kiln technologies studied at home and abroad are also decompression clarification and immersion combustion. The clarification under reduced pressure is to draw the glass into a vacuum chamber. After degassing and clarification, the glass is formed by homogenization and cooling. Immersion combustion involves placing a burner at the bottom of the kiln, blowing gas and oxygen into the glass, and burning in the liquid phase. In this way, the strong agitation caused by combustion can be utilized to increase the heat transfer of the kiln gas and the glass, accelerate the physical and chemical changes, and achieve the effects of reducing energy consumption, increasing production, and improving quality.

2.1, deep clarifier technology

Deep clarification tank technology is to increase the depth of the clarification tank after the kiln to facilitate the clarification of the molten glass. This technology can effectively reduce the reflux of the molten glass, greatly reducing the energy loss caused by heating the returning molten glass, thereby reducing energy consumption. The depth of the clarification tank in the deep clarification tank technology is generally 100-300 mm deeper than the depth of the melting tank, and some even add about 50% of the depth of the melting pool, but the depth of the clarifier should not be too deep, otherwise the color material is produced. There is a problem that energy is consumed because the feed temperature is too low. The deep clarifier tank must be used in conjunction with the kiln. The height of the kiln is generally 1/2 of the depth of the puddle. The shape of the kiln is preferably sloped, which extends the service life of the kiln and accelerates clarification. In addition, after the deep clarifier is used, the service life of the fluid hole can be increased due to the lower temperature of the molten glass flowing through the fluid hole. In order to prevent the clogging of the fluid hole due to the decrease of the temperature of the glass liquid when the colored glass is melted, an anti-blocking electrode should be provided at the fluid hole, and the fluid hole should be dredged if necessary.

2.2, decompression clarification technology

The vacuum clarification technique is to provide a vacuum degassing device in the cooling portion of the melting furnace to reduce the pressure in the gas space above the cooling portion, and to forcibly remove the bubbles in the glass by the air pressure difference. The clarification under reduced pressure can reduce the clarification temperature, and the clarification quality is greatly improved, thereby producing good energy saving benefits. Japan's Asahi Glass's test results confirmed that the clarification temperature can be reduced from 1600 °C to 1450 °C, saving 30% of energy consumption. Due to the lowering of the clarification temperature, the life of the furnace is prolonged, the cooling section is reduced, the capital investment is saved, and the quality and yield of the glass are improved.

3. Optimize glass melting design

A major technological advancement in the design of glass melting furnaces is the rise of digital melting simulation technology for glass melting furnaces. The digital-analog simulation technology can optimize the design of the glass melting furnace. It utilizes the actual experience data of the glass melting furnace and establishes an expert database system, which can easily simulate the improved effect of the furnace design on the computer and accelerate the design improvement and actual verification. Process, which greatly saves time and cost and eliminates uncertain risks. The basic design parameters of the glass melting furnace include the aspect ratio of the melting furnace, the depth of the molten pool, and the height of the kiln. The retention time of the glass liquid or the temperature at which it reaches the fluid hole has an important influence on the energy consumption of the glass melting furnace. The application of bubbling and pre-kiln fluxing electrodes in the hot spot of the glass melting furnace can form a vertical flow, thereby enhancing the convection of the molten glass. Bubbling and fluxing electrodes must be used reasonably according to the type of glass produced and the characteristics of the kiln.

Bubbling can strengthen the backflow of the molten glass from the hot spot to the feed port. The bubbles rising on the surface of the glass can prevent the batch from drifting to the discharge end, and can also drive off the possible foam layer of the glass surface, which is beneficial to the heat radiation. Conduction of molten glass. The bubbling operation cost is very low, and the main cost is the cost of compressed air. Moreover, the bubbling does not input heat to the glass. The only problem is that it must be used correctly, otherwise it will lead to increased erosion of the refractory material at the bottom of the pool.

The flow rate of the vertical flow generated by the pre-kiln fluxing electrode is lower than that of the bubbling. The heat input from the fluxing electrode increases the temperature at which the glass liquid is returned to the feed port, that is, the temperature of the glass liquid under the blanket is increased, which contributes to the melting of the batch material. Since the glass flow velocity of the fluxing electrode is low, the temperature of the glass liquid entering the fluid hole is also low, which is favorable for the reduction of the energy consumption of the glass.

4. Optimize the design of glass kiln waste heat power generation boiler

The glass kiln waste heat power generation uses a large amount of medium-low temperature and low-quality exhaust gas discharged from the tail of the glass production line to generate a certain pressure of superheated steam through the waste heat boiler, which promotes the conversion of the thermal energy and mechanical energy of the steam turbine, and then drives the generator to generate electricity. The use of residual heat in the glass kiln can achieve self-sufficiency in electricity production in the glass production process, and also provide steam and hot water for glass production. The promotion and application of this technology can reduce the energy consumption and environmental pollution of the glass production process, and has good economic and social benefits.

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