1. Carbon emission source of sand casting production system
A large amount of waste gas produced by sand casting production system mainly comes from pouring process, core making process and smelting process. In the casting process, the main component of the binder produced by the hot vaporization is the waste gas of non methane hydrocarbon, the amount of which is about 1% ~ 3% of the coating amount. When the sand core is mixed with sand and baked, a small amount of organic waste gas will be produced, which is about 0.1% of the resin amount, while the resin content in the sand core is usually 0.8% ~ 1.2%. In fact, the direct carbon emission of the sand casting production system mainly comes from the smelting process, including the combustion of fuel and the chemical change of slag making agent. In the process of cupola melting, a large amount of CO2 will be produced by combustion of fuel such as coke, which is an important source of carbon emission in sand casting production system. Secondly, the CO2 produced by the chemical change of the slag making agent (CaCO3) in the smelting furnace is also the source of the direct carbon emission of the sand casting production system on site. The emission can be calculated by the furnace burden ratio and the relevant chemical change equation in the smelting process.
However, it is obviously unscientific to simply regard the on-site direct carbon emission as the total carbon emission of the system. Low carbon manufacturing emphasizes the reduction and control of carbon emissions in the whole life cycle of products. Therefore, in addition to direct carbon emissions on site, system carbon emissions also include indirect carbon emissions caused by direct or indirect energy consumption, including indirect emissions caused by power and material consumption, And the direct emission caused by the consumption of other primary energy (such as coal), secondary energy (such as coke, gas, steam, gasoline and diesel), or energy consuming working medium (such as compressed gas and oxygen).
2. Evaluation boundary of sand casting production system
Taking the sand casting process as the research object, the calculation boundary of total CO2 emission is established on the basis of the analysis of the whole process of sand casting production. Through the analysis of sand casting process flow, it can be seen that the typical sand casting production system is mainly composed of three subsystems: (1) raw material system, mainly pig iron processing process, from iron ore mining, cleaning, sintering to blast furnace ironmaking; (2) process system, which is the main process flow, including molding, core making, box closing, smelting, pouring, sand dropping, cleaning and other basic processes; (3) The upstream system is composed of auxiliary material module, fuel module and energy module. The auxiliary material module includes sand raw material production, limestone mining, etc. the fuel module includes the mining and production of coke, raw coal, etc. the energy module includes the mining and production of all kinds of primary and secondary energy besides fuel,