With the rapid increase of the social demand for carbon fiber, the current production capacity of carbon fiber can not keep pace with the development, only relying on the expansion of production to solve this problem.
Most of the existing production equipment USES resistance heating, especially the production line of 100 tons and above. From the point of view of equipment, the resistance heating method has low thermal efficiency, uneven heating and unstable product performance, which greatly increases the production cost of carbon fiber.
Very few of them adopt intermediate frequency induction heating, but also have the problem of high energy consumption.
If we want to solve the above problems, we must start from the production process and equipment.
Firstly, the induction heating method is adopted, and then the reasonable working frequency is selected.
It is well known that energy consumption is one of the most important factors directly affecting the production cost of carbon fiber. How to reduce energy consumption? It is difficult to achieve under the current heating mode. Only by replacing the existing heating mode, can we really achieve the purpose of reducing energy consumption.
Induction heating has the characteristics of uniform heating, fast heating and cooling speed. The induction heating method can greatly improve the temperature uniformity of the equipment, especially suitable for large carbon fiber production lines at high temperature carbonization and graphitization. According to the characteristics of induction heating, which can rapidly heat up and cool down without causing adverse effects on the equipment, the start-stop process of resistance heating mode can be eliminated, which greatly reduces energy consumption and saves energy. Firstly, the consumption of a large part of energy can be reduced from the process.
The energy saving varies from manufacturer to manufacturer due to different processes. However, using induction heating and choosing reasonable working frequency for carbon fiber continuous high temperature carbonization and graphitization process can reduce the energy consumption by 40% ~ 60%.
What is the reasonable frequency choice? At present, the frequency used is 1KHz or 2.5khz, whose energy-saving effect is not very obvious. Considering the principle of induction heating and the strength of the equipment, it is reasonable to choose a working frequency of 20KHz or higher. Compared with 2.5KHz, its energy consumption is reduced by more than 50%, which is very objective and of great significance to the development of carbon fiber in China.
From the perspective of the heating element, the impact on heating performance and energy consumption and energy saving and consumption reduction.
At present, most of the continuous high temperature carbonization and graphitization equipment of carbon fiber use graphite heaters. The use of graphite heaters has certain limitations, mainly in terms of the volume size of the heating body, and the length, width and height are limited by graphite billets. If carbon/carbon composite material is used as heating element, the problem of limited volume and size of heating element can be well solved.
With the adoption of carbon/carbon composite heating elements, a problem arises, that is, the heating efficiency. Most of the current induction heating methods are intermediate frequency induction heating, with the frequency of 1KHz or 2.5khz. With the increase of equipment power demand, the working frequency will gradually decrease. In order to achieve a certain efficiency under this parameter, the thickness of the heating element must be increased, and the energy consumption also increases accordingly. From the perspective of economy, using carbon/carbon composite heating material with a general thickness of 8mm ~ 10mm (graphite material heating material can also be processed to this thickness), if the traditional 1KHz or 2.5khz intermediate frequency induction heating is very unreasonable, we must improve the heating frequency to achieve the purpose of improving heating efficiency. This is also in line with the above mentioned energy conservation measures.
On 2018-08-08 11:45:46
