Computational Fluid Dynamics Lab, Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas, USA.
J Air Waste Manag Assoc. 2019 Jan;69(1):119-130. doi: 10.1080/10962247.2018.1525443. Epub 2018 Oct 31.
Flares are important safety devices for pressure relief; at the same time, flares are a significant point source for soot and highly reactive volatile organic compounds (HRVOCs). Currently, simple guidelines for flare operations to maintain high combustion efficiency (CE) remain elusive. This paper fills the gap by investigating the characteristics of the incipient smoke point (ISP), which is widely recognized as the condition for good combustion. This study characterizes the ISP in terms of 100-% combustion inefficiency (CE), percent opacity, absorbance, air assist, steam assist, air equivalence ratio, steam equivalence ratio, exit velocity, vent gas net heating value, and combustion zone net heating value. Flame lengths were calculated for buoyant and momentum-dominated plumes under calm and windy conditions at stable and neutral atmosphere. Opacity was calculated using the Beer-Lambert law based on soot concentration, flame diameter, and mass-specific extinction cross section of soot. The calculated opacity and absorbance were found to be lognormally distributed. Linear relations were established for soot yield versus absorptivity with > 0.99 and power-law relations for opacity versus soot emission rate with ≥ 0.97 for steam-assisted, air-assisted, and nonassisted flares. The characterized steam/air assists, combustion zone/vent gas heating values, exit velocity, steam, and air equivalence ratios for the incipient smoke point will serve as a useful guideline for efficient flare operations.: A Recent EPA rule requires an evaluation of visible emissions in terms of opacity in compliance with the standards. In this paper, visible emissions such as soot particles are characterized in terms of opacity at ISP. Since ISP is widely recognized as most efficient flare operation for high combustion efficiency (CE)/destruction efficiency (DE) with initial soot particles formed in the flame, this characterization provides a useful guideline for flare operators in the refinery, oil and gas, and chemical industries to sustain smokeless and high combustion efficiency flaring in compliance with recent EPA regulations, in addition to protecting the environment.
火焰是用于减压的重要安全装置；同时，火焰也是烟尘和高反应性挥发性有机化合物（HRVOCs）的重要点源。目前，保持高燃烧效率（CE）的火炬操作简单指南仍然难以捉摸。本文通过研究广泛认为是良好燃烧条件的初始烟雾点（ISP）的特性来填补这一空白。本研究从 100-%燃烧效率（CE）不达标、不透明度、吸收率、空气辅助、蒸汽辅助、空气当量比、蒸汽当量比、出口速度、废气净加热值和燃烧区净加热值等方面对 ISP 进行了特征描述。在平静和有风条件下，根据浮力和动量主导羽流在稳定和中性大气中的火焰长度进行了计算。不透明度是根据烟尘浓度、火焰直径和烟尘质量比消光截面，利用 Beer-Lambert 定律计算得出的。计算得出的不透明度和吸收率呈对数正态分布。建立了蒸汽辅助、空气辅助和非辅助火炬的烟尘产率与吸收率之间的线性关系， ＞0.99，以及不透明度与烟尘排放率之间的幂律关系， ≥0.97。对初始烟雾点的蒸汽/空气辅助、燃烧区/废气加热值、出口速度、蒸汽和空气当量比进行了特征描述，这将为高效火炬操作提供有用的指南。：最近的 EPA 法规要求根据标准，以不透明度评估可见排放。在本文中，在 ISP 处对可见排放物（如烟尘颗粒）进行了不透明度的特性描述。由于 ISP 被广泛认为是初始烟尘颗粒在火焰中形成时具有高燃烧效率（CE）/破坏效率（DE）的最有效火炬操作，因此这种特性描述为炼油厂、石油和天然气以及化工行业的火炬操作人员提供了有用的指南，以遵守最近的 EPA 法规，实现无烟和高燃烧效率的火炬燃烧，同时保护环境。
