What Temperature is a Silicon Furnace?

What Temperature is a Silicon Furnace?

Industrial Silicon Furnace Temperature

The temperature management of industrial silicon furnaces is a key link in the production process, which directly affects product quality and equipment life. Furnace temperature control needs to be combined with the characteristics of raw materials, operating standards, and equipment status to establish a dynamic adjustment mechanism to ensure production efficiency and safety. The following outlines the key points of temperature control from a practical application perspective, covering common problem solutions and operational details.

The temperature of the silicon furnace is usually controlled within the range of 1700 ℃ to 1900 ℃, and different smelting stages correspond to different temperature requirements. It is recommended to maintain around 1650 ℃ during the initial feeding stage to avoid thermal shock damage to the lining material. When the melting rate of the furnace material reaches 60%, gradually raise the temperature to 1750 ℃ to promote the reduction of silicon element.

The refining stage needs to be precisely controlled at 1820 ± 10 ℃, at which point the purity and crystal form of metallic silicon are optimal.

The operator needs to record the data of three temperature measurement points at the top, waist, and bottom of the furnace every hour, draw a temperature curve chart, and immediately activate the three-level response mechanism if any abnormal fluctuations are found: adjust the air supply volume within 5% of the temperature deviation, activate the backup heating system within 10% of the deviation, and execute the emergency shutdown procedure if the deviation is 15%.

Common temperature anomalies include local overheating caused by electrode breakage, melting point changes caused by impurities in raw materials, and temperature control failure caused by cooling system failures.

An accident occurred in a certain smelting plant where the furnace bottom temperature suddenly increased by 200 ℃. Upon investigation, it was found that poor contact was caused by oxidation of the carbon electrode joint, resulting in uneven current distribution and high arc temperature.

To deal with such problems, a five step detection process needs to be established: first cut off the main power supply, then scan the furnace body with an infrared thermal imager, then check the pH value of the circulating water, test the electrode lifting system, and finally sample and analyze the composition of the slag.

The focus of daily maintenance is on the detection of electrode paste filling density, requiring the measurement of electrode consumption per shift to ensure a stable drop speed of 3-5 centimeters per hour.

In terms of energy conservation and consumption reduction, a certain enterprise achieved an annual electricity cost savings of 3.8 million yuan by improving the insulation layer structure. The specific method is to use composite refractory materials and add nano aerogel insulation board on the outside of the furnace wall to reduce the surface temperature of the furnace body from 280 ℃ to 150 ℃ and reduce the heat loss by 23%.

Implement a waste heat recovery system to recover the flue gas temperature from 650 ℃ to below 200 ℃. This heat energy is converted into steam for the raw material drying process, reducing overall energy consumption by 18%.

There are three points to note when selecting temperature monitoring equipment: the thermocouple must be of Platinum Rhodium 30 Platinum Rhodium 6 type, with a maximum temperature resistance of 1850 ℃; The measurement accuracy of infrared thermometer needs to reach ± 0.5%; The data acquisition system should have temperature gradient analysis function.

A certain testing case showed that after using a regular K-type thermocouple for three months, there was an 8% measurement deviation, resulting in three batches of products exceeding the carbon content limit. It is recommended to calibrate the instrument with a blackbody furnace every quarter and perform error correction at three reference points of 1500 ℃, 1700 ℃, and 1900 ℃.

Operation training should set up simulated exercise scenarios, such as emergency cooling plans in case of sudden water outage. The drill includes manual activation of the backup reservoir, adjustment of the opening of the flue gas discharge valve, emergency addition of silica powder for heat absorption, and other operations.

The standardized operating procedure established by a certain factory stipulates that when the cooling water pressure is below 0.3MPa, the furnace temperature must be lowered to below 1600 ℃ within 10 minutes; Immediately execute the shutdown protection procedure when the pressure is below 0.2 MPa.

In terms of environmental impact, improper temperature control may lead to the generation of dioxin like substances. When the furnace temperature remains below 600 ℃, chlorine containing raw materials are prone to produce toxic gases. A certain environmental case shows that by installing multi-stage combustion chambers to reheat the flue gas to above 850 ℃, the concentration of dioxin emissions decreased from 2.3ng-TEQ/m ³ to 0.05ng-TEQ/m ³, meeting the EU emission standards.

The direction of technological transformation includes the application of intelligent temperature control systems. An AI prediction model deployed by a certain enterprise can predict temperature trends 2 hours in advance with an accuracy rate of over 92%. The system automatically generates a temperature adjustment plan by analyzing 32 parameters (including raw material moisture content, electrode current harmonics, cooling water temperature difference, etc.), which increases the product qualification rate by 7 percentage points. However, attention should be paid to the iterative updating of the algorithm model. It is recommended to supplement more than 200 sets of production data every month to retrain the model.

The focus of safety management is on the prevention of temperature related accidents, requiring the installation of four layers of protective devices: automatic power-off device for overheating, interlocking device for cooling water flow, emergency nitrogen injection system, and furnace tilt alarm device. A certain accident analysis report pointed out that the probability of silicon leakage accidents is 47% higher in equipment without furnace tilt sensors installed. When the tilt exceeds 3 degrees, silicon liquid may penetrate the furnace lining and cause significant losses.

In a process improvement case, a research team developed a gradient heating method and used an alternating temperature field of 1900 ℃/1750 ℃ in the later stage of smelting to reduce the boron impurity content in industrial silicon from 25ppm to 8ppm. This method utilizes the thermal stress generated by temperature changes to promote impurity precipitation, and when combined with an electromagnetic stirring device, can increase impurity removal efficiency by 40%, but it requires modification of the existing heating control system.