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首页> 外文期刊>Journal of the air & waste management association >Pseudo-source parameters for flares: Derivation, implementation, and comparison
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Pseudo-source parameters for flares: Derivation, implementation, and comparison

机译：耀斑的伪源参数：派生，实现和比较

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The United States Environmental Protection Agency (US EPA) flare pseudo-source parameters are over 30 years old and few dispersion modellers understand their basis and underlying assumptions. The calculation of plume rise from the user inputs of pseudo-stack diameter, temperature and velocity have the most influence on air dispersion model predictions of ground-level concentrations. Regulatory jurisdictions across Canada, the United States and around the world have adopted their own approach to pseudo-source parameters for flares; all relate buoyancy flux to the heat release rate, none consider momentum flux and flare tip downwash as adopted by the Alberta Energy Regulator (AER). This paper derives the plume buoyancy flux for flares burning a gas in terms of combustion variables readily known or calculated without simplifying assumptions. Dispersion model prediction sensitivity to flared gas composition, temperature and velocity, and ambient conditions are now correctly handled by the AER approach. The AER flare pseudo-source parameters are based on both the buoyancy and momentum flux, thus conserving energy and momentum. The AER approach to calculate the effective source height for flares during varying wind speeds is compared to the US EPA approach. Instead of a constant source for all meteorological conditions, multiple co-located sources with varying effective stack height and diameter are used. AERMOD is run with the no stack tip downwash option as flare stack tip downwash is accounted for in the effective stack height rather than the AERMOD model calculating the downwash incorrectly using the pseudo-source parameters. The modelling approaches are compared for an example flare. Maximum ground level predictions change, generally increasing near the source and decreasing further away, with the AER flare pseudo-source parameters. It's time to update how we model flares. Implications: What are the implications of continuing to model flare source parameters using the overly simplified US EPA approach? First, the regulators perpetuate the myths that the flare source height, temperature, diameter and velocity are constant for all wind speeds and ambient temperatures. Second, that it is acceptable to make simplifying assumptions that violate the conservation of momentum and energy principles for the sake of convenience. Finally, regulatory decisions based on simplified source modelling result in predictions that are not conservative (or realistic). The AER regulatory approach for flare source parameters overcomes all of these shortcomings. AERflare is a publicly available spreadsheet that provides the "correct" inputs to AERMOD.
机译：美国环境保护署（US EPA）的火炬伪源参数已有30多年的历史了，很少有散布建模者理解其基础和基本假设。从用户输入的伪烟囱直径，温度和速度计算烟羽上升对地面浓度的空气扩散模型预测影响最大。加拿大，美国和世界各地的监管辖区都采用了自己的方法来估算火炬的伪源参数。所有这些都将浮力通量与放热率相关，都没有考虑到艾伯塔省能源监管局（AER）所采用的动量通量和火炬头向下冲洗。本文根据已知的或无需简化假设即可计算出的燃烧变量，得出了燃烧火炬的烟气浮力通量。现在，通过AER方法可以正确处理扩散模型预测对火炬气成分，温度和速度以及环境条件的敏感性。 AER耀斑伪源参数同时基于浮力和动量通量，因此可以节省能量和动量。将AER方法计算出不同风速下火炬的有效源高度与美国EPA方法进行了比较。代替所有气象条件的恒定源，使用具有不同有效烟囱高度和直径的多个并置源。 AERMOD使用无烟囱末端向下冲洗选项运行，因为火炬烟囱末端向下冲洗是在有效烟囱高度中考虑的，而不是AERMOD模型使用伪源参数错误地计算了冲洗深度。比较了示例火炬的建模方法。最大地面预测值随AER耀斑伪源参数的变化而变化，通常在源附近增加，而在远处减小。现在是时候更新耀斑建模了。含义：使用过于简化的美国EPA方法继续对火炬源参数建模会产生什么影响？首先，调节器使火炬源高度，温度，直径和速度在所有风速和环境温度下恒定不变的神话得以延续。其次，为方便起见，做出违反动量和能量守恒原理的简化假设是可以接受的。最后，基于简化源模型的监管决策所得出的预测并不保守（或现实）。火炬源参数的AER监管方法克服了所有这些缺点。 AERflare是可公开获得的电子表格，可为AERMOD提供“正确”的输入。

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