# Calculation model of energy consumption and energy efficiency ratio in Moldless sand casting process

Sand casting is an energy intensive production process. The production energy consumption per unit casting reflects the energy intensity of casting production to a certain extent. In the mass production of castings, making a reasonable consumption quota for casting production is helpful to the optimization of production structure and energy saving. According to the characteristics of Moldless sand casting process, the main forms of energy consumption are energy materials and electric energy consumption in production process. Among them, energy materials, including natural gas and coke, are consumed during hot metal smelting and are recorded as energy material resources. The energy consumption of Moldless sand casting process involves three parts: molten iron smelting energy consumption, production auxiliary equipment energy consumption and material recovery energy consumption. The energy consumption of material recovery is related to the recovery of waste castings and used sand. Therefore, the energy consumption composition of Moldless sand casting can be expressed as the formula:

Where, EN α Represents the energy consumption of molten iron smelting in medium frequency furnace; EN β Represents the equipment power consumption of the casting production line; EN γ Indicates the energy consumption of material recovery in the casting process.

The energy consumption of medium frequency furnace is measured by the melting energy consumption per ton of molten iron. The melting energy consumption per unit casting is related to the actual melting plan and production capacity distribution. The number of castings that can be poured in a single molten iron smelting can be expressed as the formula:

G1 is the quality of molten iron produced by medium frequency furnace in a single time; η The proportion of production plan for producing the casting; δ Is the loss rate of molten iron caused by transportation and ladle surplus before pouring process; Gcast is the quality of casting blank.

The melting energy consumption per unit casting can be expressed as the formula:

Among them, PI is the power consumption per ton of molten iron, and other symbols are consistent with the above.

In the energy consumption calculation of production auxiliary equipment and material recovery, the rated power of the equipment is recorded as the average power, and the equipment operation time evenly distributed to the unit casting is recorded as the working time. The energy consumption of production auxiliary equipment and material recovery per unit casting can be expressed as the formula:

Where, EN β̅̅̅̅̅ Represents the average power of the auxiliary equipment of the th type; t β Represents the second β Working hours of auxiliary equipment; En γ̅̅̅̅̅ Represents the second γ Average power of equipment of material recovery line; t

γ Represents the second γ The working time of a material recovery line equipment.

To sum up, the production energy consumption per unit casting can be expressed as the formula:

All symbols are consistent with the above.

Energy efficiency ratio can reflect the efficiency of energy conversion, as well as the intensity of production capacity and energy-saving potential. In this paper, the energy efficiency ratio of production unit casting is the ratio of production efficiency of casting method (single technology or composite forming) to production energy consumption per unit casting, which can be expressed as the formula:

Where, TST represents the standard working hours of qualified castings of the production unit; TWF represents the working hours of workers in the f-th casting process; NF number of workers invested in the f-th casting process; Tlosf represents the time loss caused by suspension or rework in the f-th casting process; Other symbols are consistent with the above.

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