求翻译：四效降膜蒸发系统具有传热快、节能和物料停留时间短的特点,特别适合于浓缩含热敏性成分的物料,因此,广泛应用在轻工、食品及化工行业。近些年来,多效降膜蒸发系统在我国使用的范围和数量有较大的增加,照搬国外或其它物料的浓缩工艺和设备的问题较为普遍,造成投资和能源的较大浪费[6-7]。本文研究的目的是用膜蒸馏技术取代四效降膜蒸发系统浓缩谷氨酸发酵液中的谷氨酸，提高谷氨酸的浓度。通过气相色谱仪对膜蒸馏产水进行检测，表明膜蒸馏产水可以得到回用。是什么意思？

Four-effect falling film evaporator system with heat transfer, energy efficiency and residence time characteristics, is particularly suitable for the material concentrate containing heat-sensitive ingredients, therefore, widely used in light industry, food and chemical industries. In recent years, m

4 energy efficiency of a heat transfer film evaporation system, dwell time and the Material energy short features, which is particularly suitable for use in espresso-heat sensitive components of the material, therefore, widely used in light industry, food and chemical industries. In recent years, a