Structural Analysis of LCA for Chemical Products

基于CO2累积排放单位的概念，提出了一种定量评价石油化工产品生命周期内向大气排放CO2总量的方法。在本项目开发的生命周期评价方法中，以下两个问题有待解决。第一个是所谓的分配或划分问题，它决定如何将排放分配给存在两种以上产品的单位中的每一种产品。第二个问题是对回收物料的CO_2排放单位应确定为多少，在本项目设计的LCA计算机程序中，设计了适用于任何分配政策的参数化程序，而对回收物料的CO_2排放单位则确定为零。利用该程序，通过阅读与石油化工生产过程的物质流和能量流直接对应的库存表上的数据，自动计算出石油化工产品及其回收产品的CO_2累积排放量，并根据累积排放量对以下两种情况进行了生命周期评价：回收用过的PET瓶到地毯上（材料回收）和通过焚烧用过的EPS托盘回收能源（热回收）。根据生命周期评估，这两个周期都是可验证的。

A quantitative method to evaluate the total amount of CO_2 which is emitted to atmosphere over the life cycle of petrochemicals was proposed based on the concept of cumulative CO_2 emission unit. In the LCA methods developed in this project, the following two problems remain to be solved. The first is the socalled allocation or partitioning problem which determines how to allocate the emission to each product in the unit where more than two products are present. The second is the problem that how much CO_2 emission unit should be specified to the materials to be recycled.In the LCA computer program designed in this project, a parametric procedure is designed so as to be applicable to any allocation policy, while zero CO_2 emission unit is specified to the materials to be recycled. By using this computer program, the cumulative CO_2 emission units of petrochemicals and its recycled products are caluculated automatically reading the date on the inventory table which is designated directly corresponding to material and energy flows of petrochemical manufacuring process.Based on the cumulative CO_2 emission unit, the life cycle assessment was achieved for the following two cases ; recycling of used PET bottles to carpet (material recycling) and energy recovery by incineration of used EPS trays (thermal recycling). Both recycles have been concluded to be recommendable in view of LCA.