The latest development of glass all-electric melting and electric-assisted melting furnace technology

Nanjing Baisheng Glass Technology Co., Ltd. and Nanjing Baisheng Kiln Engineering Co., Ltd. were established in February 2006 and January 2014 respectively. Is a professional company engaged in glass factory (kiln) design, kiln (equipment) construction and installation and glass production technical services. The company mainly serves the glass factory design of flat glass, photovoltaic calendered glass, electric light source glass, daily-use glass, water glass and ceramic frit production lines, glass engineering installation and construction, firing and baking kiln, commissioning and related technical training, technical services, and professional companies for hot and cold repair of glass kilns. The registered capital of the company is 1.6 million yuan. At present, there are 25 professional engineers and technicians, including 10 with senior professional titles and 30 middle and senior technicians. The company not only has glass engineering design, professional kiln construction, professional technology and construction team for hot repair of large and medium-sized glass kilns.

With the research and development of molybdenum electrode, especially the molybdenum electrode is put into use safely, which promotes the commercialization of glass electrofusion and electrofusion. About 60 years ago, Larry Penberthy, an American, adopted electric flux for the first time. In the early stage of the development of electric flux technology, in order to use molybdenum electrode safely, a special electrode cooling system was needed to ensure that molybdenum electrode was not oxidized at 600℃. The first electrode cooling water jacket adopts sputtering cooling structure, and the water jacket is tubular structure. The internal water pipe sprays cooling water to the end of the water jacket, and then the water flows back along the molybdenum electrode, and finally enters the water pool of the water circulation system through the return pipe. This kind of water jacket has remarkable effect, and it is a good cooling device for the side wall electrode. The water jacket has the advantages of simple and practical structure, low energy consumption and so on, but it also has shortcomings and deficiencies. This kind of sputtering cooling water jacket does not require high quality of circulating water, but it is not suitable for today's increasingly large-scale glass electric melting furnace. With the increase of kiln scale and the realization of more effective bottom-inserted electrode technology, an improved electrode water jacket has been formed, that is, a water jacket with internal waterway. This kind of water jacket is widely used in the current glass industry, but it also has many shortcomings, mainly

(1) easy to block;

(2) The requirements of thermal shock resistance are put forward for the surrounding refractories;

(3) There is a certain danger in propelling the electrode;

(4) It is difficult to recycle in the later period of kiln use.

In recent years, the furnace life of kiln has increased rapidly, which requires that the cooling water jacket can be used for 15 years in continuous operation process.

The biggest problem of electrode water jacket lies in the process of electrode propulsion. According to the electrode propulsion design, it is generally required to be promoted once every 3 months at the earliest and once every 7 years at the least, such as in the float furnace designed by FIC. The difference of propulsion time is so great, which is mainly determined by the type of glass, melting rate, especially the propulsion design structure. The electrode water jacket is usually damaged in the process of propulsion, mainly because the cooling water needs to be turned off in order to propel the electrode, so that the overall temperature of the water jacket rises and the solidified glass near the water jacket softens to achieve the purpose of propulsion. Almost all electrode water jackets are made of heat-resistant stainless steel, which needs to withstand the high temperature of 1100℃. However, after pushing the water jacket, the biggest problem appears in the re-entry of water into the water jacket. Because the temperature of the front end of the water jacket is as high as 1100℃, cooling water needs to be added very slowly to prevent damage caused by huge temperature difference. However, because the kiln operators are already hot and tired in the process of electrode propulsion, they hope to finish the work as soon as possible, and the water is often not slow enough in the actual operation.

Obviously, the cooling water is injected too fast and causes thermal shock, but the time that has been delayed in the process of propulsion will also cause damage to the water jacket if it is not advanced in time. Once thermal shock occurs, the water jacket weld will crack or block the water jacket, which will cause permanent damage to the water jacket, thus causing splashing and waste of cooling water. Because most propulsion systems are about vertical electrodes now, the water loss flowing to the ground is very high, which leads to electrode drilling or changing electrode position. This is a work that needs in-depth study and is expensive.

In addition, when pushing the electrode, the introduced cooling water will produce hot steam which is not easy to be observed after reaching the high temperature part of the water jacket, and it is easy to burn the operators nearby. In any case, cooling water still needs to be introduced slowly, and some companies use air cooling systems to ease this process. With the passage of time, the cooling water jacket is closed, and even if treated water is used, it will be blocked slowly, and finally the cooling water stops running, so sputtering cooling has to be adopted. Sometimes the counter-flow of cooling water may also remove the blocked water jacket, and another solution is to inject citric acid. If the cooling water flow in the water jacket decreases, citric acid injected into the system can reduce the chance of water jacket being blocked. When congestion occurs, some companies control the cooling circuit by opening another independent waterway. FIC developed a replaceable independent waterway, and later developed into multiple independent waterways.

To sum up, the water cooling coil is the core of these standard water jacket systems, which not only absorbs the heat at the front end of the water jacket, but also absorbs the heat around the water jacket. This also leads to heat absorption from refractories and star cracks. Some suppliers have recognized this problem and wrapped insulating materials around the water jacket to reduce its influence. FIC invented a new water jacket as early as 20 years ago, which overcame all the above shortcomings.

FIC has produced more than 7,000 high' Q' water jackets, representing the current advanced level, and the detachable waterway is its main feature. This waterway can be dismantled by ordinary employees in less than ten minutes, and only three tools are needed to completely separate and complete the whole process. Because of its large cross-sectional area, the requirements for the quality of cooling water are not high. In fact, when necessary, you can also use river water directly. The detachable waterway does not directly contact the water jacket itself, and it has an air barrier to ensure that the cooling water only acts on the front end of the water jacket. In this way, the star crack of refractory caused by thermal shock is reduced or completely eliminated. Besides, this kind of water jacket is designed by experienced people, who have rich experience in electric flux and electric melting furnace. Anything that may lead to failure has been taken into account in the design. For example, in order to prevent the detachable waterway from sticking to other structures of the water jacket, a jacking system is designed to ensure the normal extraction of the waterway. Similarly, the thermocouple used to measure the temperature of the front end of the water jacket is independent, so it is necessary to measure the temperature of the high-temperature part of the water jacket and the refractories more accurately, and accurately display the softening point of the glass around the water jacket to ensure the advancement of the electrode. This means that it is easy to determine when to advance the electrode. On this issue, it should also be noted that never push the water jacket under the condition of using the water jacket, which will not only damage the surrounding refractory materials, but also make the whole water jacket fall apart. The fixing method of FIC is to apply appropriate pressure to the electrode without damaging the electrode and refractory bricks by using the screw structure. If too much pressure is applied, the screw will be damaged, but the refractory and the water jacket itself will not be damaged. If necessary, these screws are easy to replace, and they are standard parts everywhere. If the refractory material is found to be accidentally damaged, the fixing structure can also pull out the water jacket if necessary.

Another important innovation of this high' Q' water jacket is that it is not necessary to cut off the cooling water when pushing the electrode, because the cooling water coil is movable. The cooling water pipe is retracted to stop contacting the front end of the water jacket and the electrode, so that the glass can naturally heat up. Because the cooling water has not stopped, there is no danger of overheating steam and no burn to the staff. This is also an important feature of the current health and safety labor law.

Nanjing Baisheng Glass Technology Co., Ltd. is mainly engaged in glass kiln engineering, glass kiln design and glass kiln construction services. It is a professional glass engineering design, glass kiln construction and glass production technical service company.