Application of electric heating to increase the temperature of carbon dioxide

Published on:

2023-04-17 10:06

The chemical reaction of blowing sand from liquid CO2 glass is an endothermic reaction. The higher the temperature, the faster the chemical reaction takes place. From the rule from temperature to reaction rate, it can be seen that when the temperature rises every 10 ° C, the reaction rate constant increases 2-4 times compared to the original rate constant; at low temperature, the rate of the chemical reaction decreases. Especially in winter, due to the low ambient temperature, sodium silicate sand is not easy to solidify by blowing CO2, which prolongs the mold removal time, not only consumes a lot of CO2, but also easily causes overflow, so that the strength of the molding mixture cannot meet the requirements of the technological regulations.

One way to solve the low rate of solidification of liquid glass sand in winter is to heat CO2 to a certain process temperature to increase the solidification rate of liquid glass sand. To achieve this technological goal, some enterprises will adopt the method of centralized gas supply to the CO₂ merger, and then carry out heating and transportation of CO₂ by heating. The electric heater is installed in front of the high and low pressure reduction valves, its function is to heat the CO2 to a given temperature range of the process and prevent the reduction valve from being blocked by dry CO2 ice when liquid CO2 is evaporated due to a large amount of heat absorption.

Due to poor heat preservation in winter, the ambient temperature of the plant room is relatively low, and the transmission path of CO₂ is long, resulting in the heated gas CO₂ losing a lot of heat during the transfer process to the molding shop, thus affecting the solidification rate of the sand from the liquid glass when blown. In order to ensure that the CO₂ gas is always maintained within a certain temperature range (typically 35 ~ 40 °C) during the transmission process, a more advanced electric heating device is selected to realize the transportation of CO₂ gas with heating.

There are many types of electric heating tapes, and it is very important to choose economical and practical electric heating tapes.

First, determine the thermal loss of the pipeline in the transmission of CO2, and then select the appropriate electric heating belt according to the thermal loss of the pipeline and the maintaining temperature of the environment CO2. The maximum maintaining temperature of the electric heating belt should be higher than the average temperature. As for the method of calculating the heat loss of the pipeline, the manufacturer provides theoretical calculation formulas or empirical data tables of the pipeline heat loss in the sale of products, and users can choose according to the actual situation.

The use of electric heating and electric heating to transport CO2 gas is useful for increasing the reaction rate of liquid glass and CO2 and is one way to increase the solidification rate of liquid glass sand. It should be noted that the simple rise of the temperature of the CO₂ gas obviously cannot solve the problem of the slow rate of solidification of liquid glass sand in winter. For enterprises with good conditions, the problem can be solved by controlling the sand temperature and working environment temperature; should be done to increase the temperature of liquid glass sand and CO2, That is, to regulate the temperature of liquid glass sand and CO2 in winter. In addition, due to the pulsed supply of gaseous CO₂, a large amount of gas can be saved and more satisfactory results can be obtained.

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