Effect of droplet size, charge, and presence of surfactants on coal dust capture

液滴尺寸、电荷和表面活性剂的存在对煤尘捕集的影响

• 批准号: 8094276
• 负责人: Asit K Ray
• 金额: $ 27.47万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8094276
• 关键词: Effect; droplet; size; charge; presence

DESCRIPTION (provided by applicant): Prolonged exposure to respirable coal and silica dust particles in coal mine dust is the primary cause of Coal worker's pneumoconiosis (CWP). After a steady decline over the past years, the prevalence of CWP is on the rise in recent years. The occurrence rate of CWP is directly related to the to the exposure level to respirable coal dust, and a lowering of the coal-mine dust level standard from 2.0 to 1.0 mg/m3 has been proposed to reduce the rate. To achieve a lower dust level, newer technologies are needed. Existing technologies based on plain water sprays are not effective for the removal of airborne small particles (i.e., size less than 10 <m, or more specifically less than 2.5 <m) that pose the highest risk. This is because of large, charge neutral droplets involved in the sprays, and the hydrophobic nature of coal particles. We postulate that airborne coal particles carry significant amounts of charge, and therefore, these particles can be effectively captured by charged water droplets generated during spraying by the addition of ionic compounds. The objective of the proposed research is to understand the factors that control the capture of respirable coal particles in water droplets with an aim to develop an efficient water droplet based technology for the removal of coal mine dust. To achieve the objectives of the proposal we will (i) examine the effect of the presence of coal wetting agents in collecting droplets on the capture efficiency of coal particles, (ii) measure charge distribution in airborne coal particles to establish whether the mechanism based on Coulombic attraction can be used to capture these particles, (iii) examine whether spray droplets can be charged either negatively or positively by the addition of ionic surfactants or other ionic compounds (e.g., ionophores, and ionic liquids), and (iv) measure capture efficiency of charged droplets exposed to charged coal particles. To obtain fundamental understanding of the mechanisms involved in the capture of particles by a droplet, we propose to use an electrodynamic balance to examine the capture efficiency of single charged droplets suspended in a stream of well-characterized coal particles. In addition, we will use linear streams of highly monodisperse droplets to measure the capture of coal particles with high temporal resolution. Such a system provides a unique space-time relation; thus, by examining droplets at several distances from the generation point the capture of particles by a droplet with time can be deciphered.

描述（由申请人提供）： 长期接触煤矿粉尘中的可吸入性煤和硅尘是煤工尘肺（CWP）的主要原因。经过过去几年的稳步下降，近年来CWP的流行率呈上升趋势。煤工尘肺的发生率与呼吸性煤尘接触水平直接相关，建议将煤矿粉尘标准从2.0 mg/m3降低到1.0 mg/m3。为了降低粉尘水平，需要更新的技术。基于普通水喷雾的现有技术对于去除空气中的小颗粒（即，尺寸小于10 μ m，或更具体地小于2.5 μ m），其构成最高风险。这是因为喷雾中含有大的电荷中性液滴，以及煤颗粒的疏水性。我们假设，空气中的煤颗粒携带大量的电荷，因此，这些颗粒可以有效地捕获喷雾过程中产生的带电水滴通过添加离子化合物。拟议的研究的目的是了解控制水滴中可吸入煤颗粒捕获的因素，旨在开发一种有效的基于水滴的煤矿粉尘去除技术。为达致本建议的目的，我们将（i）研究在收集液滴时加入煤润湿剂对煤粒捕集效率的影响，（ii）测量空气中煤粒的电荷分布，以确定基于库仑引力的机制是否可用于捕集这些颗粒，（iii）检查喷雾液滴是否可以通过添加离子表面活性剂或其它离子化合物（例如，离子载体和离子液体），和（iv）测量暴露于带电煤颗粒的带电液滴的捕获效率。为了获得基本的理解，在捕获的颗粒的液滴所涉及的机制，我们建议使用电动平衡来检查的捕获效率的单个带电液滴悬浮在一个流中的特征良好的煤颗粒。此外，我们将使用高度单分散液滴的线性流来测量具有高时间分辨率的煤颗粒的捕获。这样的系统提供了一个独特的时空关系，因此，通过检查液滴在几个距离的产生点的粒子捕获液滴随时间可以被破译。