Discussion on key technical problems of waste heat

2022-08-17
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In recent years, with the continuous development of society, the market competition has become increasingly fierce. Due to the relatively large energy consumption, low thermal efficiency and cheap and abundant C1 resources in the glass industry, many enterprises use the waste heat of glass kilns to generate electricity, which can not only improve the utilization of energy, but also reduce the production cost, Improve the competitiveness of enterprises and make full use of the waste heat of glass kilns. However, from the perspective of the projects that have been operated, many enterprises still have deficiencies in the utilization technology of glass kiln waste heat, lacking a rigorous theoretical basis, which will make the utilization of glass kiln waste heat insufficient, and even cause the phenomenon of secondary waste. Therefore, this paper mainly analyzes the key technical problems of glass kiln waste heat utilization and the composition and research of frequency converters on electrical appliances

1 current situation and principles of waste heat utilization

1. 1 current situation of waste heat utilization

in recent years, waste heat power generation in China's glass industry has gradually developed, and many glass kiln waste heat power stations have been put into operation. However, from the analysis of the power station projects that have been put into operation, many enterprises still have insufficient understanding and theoretical knowledge of waste heat power generation in glass furnaces, and some enterprises even copy the experience and technology of waste heat power generation in other industries, These not only can not promote the utilization of waste heat of glass kiln flue gas, but also may cause secondary waste of resources and reduce the utilization efficiency of waste heat of glass kiln

1。 2 principles for waste heat utilization

according to a large number of investigations and research and analysis, three basic principles should be followed for the waste heat utilization and power generation technology of glass kiln: (1) waste heat power generation of glass kiln should be the supporting facilities of industrial kiln, and the corresponding working procedures and operations of waste heat during power generation should not affect the normal operation of industrial kiln, and should not affect the quality Related production and required energy consumption have other impacts. (2) During the utilization of waste heat, it is necessary to fully grasp the relevant parameter data of waste heat of flue gas, and calculate according to the actual parameter data of waste heat of flue gas and the characteristics of flue gas, so as to ensure the maximum utilization rate of waste heat and energy conversion rate and reduce the secondary waste of energy. (3) In the process of using the waste heat of glass kiln, the requirements of waste heat power generation for flue gas treatment, such as flue gas desulfurization, denitration and dust removal, should be fully considered to realize the treatment of flue gas and achieve the requirements of energy conservation, consumption reduction and environmental protection emission as far as possible

2 research on the utilization of waste heat in glass kilns

at present, China's glass kilns are equipment that heats glass raw materials at high temperature to make them undergo a series of physical and chemical reactions, and finally form clarified and homogenized liquid glass. The main parameters of the flue gas waste heat generated in the glass kiln include the main components of the flue gas, temperature, flow, pressure and the characteristics of the formed dust, etc. these parameters of the flue gas waste heat will change correspondingly with the change of the industrial kiln, but the main characteristics of the flue gas waste heat are ash deposition and corrosion, which are often affected by the consumption of fuel, the use of the glass kiln and the flue Due to the influence of air exchanger and other factors, it is necessary to accurately grasp the corresponding characteristics of flue gas waste heat when using waste heat for power generation, so that it can be used reasonably

2。 1 ash deposition characteristics of glass kiln flue gas

2. 1。 1. Causes of ash deposition of glass kiln flue gas. Glass kiln dust is prone to molten slagging when the melting fixture is made of metal at high temperature. When the flue gas temperature is higher than 600 ℃, high-temperature deposition will occur on the flue, while when the temperature is lower than 600 ℃, low-temperature deposition will occur. A large number of studies have shown that there are high-temperature deposition and low-temperature deposition on the heating pipe of the waste heat boiler of the glass furnace at the same time. Therefore, this paper focuses on the ash deposition of the glass furnace flue gas during high and low-temperature deposition. Under the high-temperature deposition state of the glass kiln, two layers of ash deposition are usually generated, which are called the inner layer and the outer layer. The inner layer is mainly scoured and attached to the wall tube surface in the form of liquid, and the outer layer is the dust deposit deposited on the inner layer. In the low-temperature deposition state of the glass kiln, due to the low temperature of the heating surface of the flue and boiler, it is mainly formed by the condensation of acid or steam on the wall pipe surface and dust. Generally, it is the product of acid corrosion, fly ash on the wall pipe surface and sulfate formed by reaction. In addition, the ash deposition on the heating surface of the waste heat boiler of the glass kiln is mainly manifested in three forms: loose ash deposition, cohesive ash deposition and adhesive ash deposition. The ash deposition on the layer closest to the wall pipe is called adhesive ash deposition, which can capture the dust particles to form the second layer of cohesive ash deposition. The outermost layer is loose ash deposition, and the phase state of the flue gas will change correspondingly with the flow rate and direction of the flue gas in the glass kiln

2。 1。 2. Effective measures to remove the ash accumulated in the glass kiln. Due to the large content of water vapor in the flue gas of the glass kiln and a large amount of alkali metals and sulfides in the dust, the accumulated ash should be cleaned when using the waste heat of the glass kiln. Practice has proved that the leading layer of ash in the glass kiln has strong adhesion and adhesion, and it is difficult to clean it. However, after a certain degree of superheat and superheated steam purging, it can effectively remove the ash deposition on the surface, reduce the low-temperature corrosion, and slow down the ash deposition rate during low-temperature corrosion

2。 2 corrosivity of glass kiln flue gas

2. 2。 1. Causes of corrosion of flue gas in glass furnace. The dust of glass kiln contains alkali metals and sulfides, and some alkali metals have low melting points, which will form high-temperature bonded ash deposits on the surface of wall tubes. However, with the gradual reduction of temperature, alkali metals will form highly corrosive compounds with water vapor under the action of sulfate, etc., and it is easier to capture the dust in flue gas and form secondary ash deposits. And the main factor affecting the acid dew point of flue gas is sulfur trioxide in flue gas, while dyes and ingredients contain certain sulfides, which will affect the acid dew point temperature in glass kiln

2。 2。 2. Waste heat boiler in glass kiln 5. Force measurement method: load sensor force measurement; Temperature selection. In order to reduce the low-temperature corrosion during the waste heat utilization of glass kiln, the wall tube temperature of the low-temperature heating surface should be higher than the acid dew point temperature of the flue gas in the temperature control, and when the flue gas temperature is lower than 2 Baidu, the wall tube temperature of the heating surface metal should be equal to the temperature of the working medium in the tube, so as to effectively avoid low-temperature corrosion. In addition, the materials of the heating surface can also be appropriately selected from some anticorrosive materials, Reduce corrosivity

2。 3. Adjustment of kiln pressure during waste heat utilization of glass kiln

in the process of waste heat utilization of glass kiln, the adjustment and control of kiln pressure is very important, which directly affects the quality of glass products and the safety of kiln equipment. Before using waste heat to generate electricity, the flue gas produced by the glass kiln will be discharged from the chimney through the regenerator. The control and adjustment of kiln pressure are mainly realized according to the extraction force of the chimney and the opening of the rotary ram. This is a natural ventilation smoke exhaust method. However, after the waste heat power station is operated, the glass kiln has changed the original smoke exhaust method and conducted forced smoke exhaust, At this time, the adjustment and control of kiln pressure are mainly realized by the working frequency of induced draft fan motor and the opening of rotary ram. Therefore, the pressure of glass kiln must be adjusted and controlled as a whole for the overall smoke exhaust system, waste heat boiler, induced draft fan and ram; During the normal operation of the induced draft fan, the kiln pressure can be stabilized by changing the opening of the regulating ram. When the induced draft fan is stopped normally, a certain pumping force will be formed to realize the adjustment and stability of the kiln pressure; When the induced draft fan is shut down due to an accident, the fast butterfly valve will be fully opened to raise the temperature of the chimney and restore the extraction force. In addition, the induced draft fan motor is equipped with a frequency converter to adjust the speed, properly adjust the kiln pressure of the glass kiln, and ensure the normal operation of the waste heat boiler of the glass kiln

3 conclusion

in the development process of the glass industry, by improving the utilization rate of glass kiln waste heat, we can effectively improve the comprehensive utilization rate of resources, which greatly promotes the sustainable development strategy of the environment. At the same time, we can also realize greater social and economic benefits through the utilization of glass kiln waste heat, so as to maximize the profits of enterprises. In addition, the flue gas, dust and other substances emitted by glass kilns contain a lot of alkali metals and sulfate, which will cause environmental pollution. The utilization of waste heat from glass kilns can greatly reduce environmental pollution, reduce the energy consumption of enterprise production, and improve the competitiveness of enterprises. Therefore, the utilization of waste heat from glass kilns should be vigorously promoted, the technology of waste heat power generation from glass kilns should be optimized, and experience should be accumulated in practice to improve the utilization rate of energy

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