Measurement of oil entrainment rates and drop size spectra from coalescence filter media
Measurement of oil entrainment rates and drop size spectra from coalescence filter media
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DOI：
10.1016/j.ces.2015.04.012
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发表时间：
2015-08-18
影响因子：
4.7
通讯作者：
Kasper, G.
中科院分区：
文献类型：
--
作者：
Wurster, S.;Kampa, D.;Kasper, G.
对聚结过滤介质的液体夹带，即流动引起的先前以液滴形式沉积的油的“吹走”，人们知之甚少，一方面是因为生成的光谱非常宽，难以用时间和尺寸分辨率来表征，特别是对于携带大部分质量的非常大的液滴。此类过滤器的运行流速比传统除雾器低得多，通常为垂直方向，具有更精细的几何形状，并且重力对夹带没有直接作用。我们提出了四种测量技术的新颖组合，用于捕获操作过程中过滤器夹带的油滴光谱，尺寸范围为 0.01-2400 μm。低于 10 μm 的直径范围结合了两种已建立的实时方法，包括电子迁移率粒子光谱仪 (EMPS；< 1 μm) 和光学粒子计数器 (OPC；0.3 至 10 μm)。新开发的基于单粒子光散射的“大液滴检测系统”（LDDS）覆盖了170μm以上的直径范围。 OPC 和 LDDS 以 1 分钟的时间分辨率连续计数并分类源自整个过滤片的所有液滴。 EMPS 间歇性地运行，从气溶胶到清洁气流的短暂切换。通过离线方法收集 OPC 和 LDDS 之间尺寸范围内的液滴并确定尺寸。该测量系统应用于使用压缩机油产生的油雾操作的两种代表性类型的玻璃微纤维介质，以表征时间分辨液滴形成速率和纳米到毫米范围内的光谱。发现可湿性和不可湿性过滤介质表现出相似的夹带特性，每种过滤介质都具有多峰液滴光谱，分别在 1-2μm 和 200-300μm 范围内有两个明显的峰值。在稳态操作期间，两种模式都是准连续产生的，大液滴以每小时几滴的速率和过滤器表面的cm（2），微米尺寸的液滴频率增加10（3）-10（4）倍。现有的间接证据表明，两种类型的纤维介质具有相同的潜在夹带机制，即在下游过滤器表面排出的油上定期形成的气泡的破裂。在当前的操作条件下，大滴的直接分离（吹走）不太可能。 (C).) 2015 Elsevier Ltd. 保留所有权利。
Liquid entrainment from coalescence filter media-i.e flow induced "blow-off" of previously deposited oil in the form of droplets is poorly understood, for one because the generated spectrum is very wide and difficult to characterize with temporal and size resolution, especially for very large drops which carry most of the mass. Such filters operate at much lower flow rates than classical demisters, often in vertical orientation, with much finer geometries, and gravity plays no direct role for entrainment. We present a novel combination of four measurement techniques used to capture the entrained oil drop spectrum from filters during operation in the size range of 0.01-2400 mu m. The diameter range below 10 mu m combines two established real time methods including an electrical mobility particle spectrometer (EMPS; < 1 mu m) and an optical particle counter (OPC; 0.3 to 10 mu m). The diameter range above 170 mu m is covered by a newly developed "large drop detection system" (LDDS) based on single particle light scattering. OPC and LDDS continuously count, and classify all drops originating from the entire filter coupon with a time resolution of 1 min. The EMPS was operated intermittently, following brief switches from aerosol to clear air flow. Drops in the size range between OPC and LDDS were collected and sized by an off-line method.This measuring system was applied to two representative types of glass microfiber media operated with oil mist generated from compressor oil, in order to characterize time resolved drop formation rates and spectra in the range of nanometers to millimeters. Wettable and non-wettable filter media were Found to show similar entrainment characteristics, each with multi-modal drop spectra having two pronounced peaks in the ranges of 1-2 mu m and 200-300 mu m, respectively. During steady-state operation both modes were generated quasi-continually, the large drops at the rate of a few drops per hour and cm(2) of filter surface, the micron size drops 10(3)-10(4) times more frequently. Available indirect evidence suggests the same underlying entrainment mechanism for both types of fibrous media, namely the break-up of air bubbles formed periodically on the oil that drains on the downstream filter face. Direct detachment (blow-off) of large drops is unlikely at the prevailing operating conditions. (C).) 2015 Elsevier Ltd. All rights reserved.