Biotrickling filters are one of the most widely used biological technologies to perform biogas desulfurization. Their industrial application has been hampered due to the difficulty to achieve a robust and reliable operation of this bioreactor. Specifically, biotrickling filters process performance is affected mostly by fluctuations in the hydrogen sulfide (H₂S) loading rate due to changes in the gas inlet concentration or in the volumetric gas flowrate. The process can be controlled by means of the regulation of the air flowrate (AFR) to control the oxygen (O₂) gas outlet concentration ([O₂]_out) and the trickling liquid velocity (TLV) to control the H₂S gas outlet concentration ([H₂S]_out). In this work, efforts were placed towards the understanding and development of control strategies in biological H₂S removal in a biotrickling filter under aerobic conditions. Classical proportional and proportional-integral feedback controllers were applied in a model of an aerobic biotrickling filter for biogas desulfurization. Two different control loops were studied: (i) AFR Closed-Loop based on AFR regulation to control the [O₂]_out, and (ii) TLV Closed-Loop based on TLV regulation to control the [H₂S]_out. AFR regulation span was limited to values so that corresponds to biogas dilution factors that would give a biogas mixture with a minimum methane content in air, far from those values required to obtain an explosive mixture. A minimum TLV of 5.9 m h⁻¹ was applied to provide the nutrients and moisture to the packed bed and a maximum TLV of 28.3 m h⁻¹ was set to prevent biotrickling filter (BTF) flooding. Control loops were evaluated with a stepwise increase from 2000 ppm_v until 6000 ppm_v and with changes in the biogas flowrate using stepwise increments from 61.5 L h⁻¹ (EBRT = 118 s) to 184.5 L h⁻¹ (EBRT = 48.4 s). Controller parameters were determined based on time-integral criteria and simple criteria such as stability and oscillatory controller response. Before implementing the control strategies, two different mass transfer correlations were evaluated to study the effect of the manipulable variables. Open-loop behavior was also studied to determine the impact of control strategies on process performance variables such as removal efficiency, sulfate and sulfur selectivity, and oxygen consumption. AFR regulation efficiently controlled [O₂]_out; however, the impact on process performance parameters was not as great as when TLV was regulated to control [H₂S]_out. This model-based analysis provided valuable information about the controllability limits of each strategy and the impact that each strategy can have on the process performance.

中文翻译：

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基于模型的好氧生物滴滤池沼气脱硫控制策略分析

生物滴滤器是进行沼气脱硫的最广泛使用的生物技术之一。由于难以实现该生物反应器的坚固和可靠的操作，因此阻碍了它们的工业应用。具体而言，生物滴滤过滤器的工艺性能主要受气体入口浓度或气体体积流量变化引起的硫化氢（H ₂ S）加载速率波动的影响。该过程可通过调节空气流量（AFR）来控制，以控制氧气（O ₂）气体出口浓度（[O ₂ ] _out）和滴入液体速度（TLV）来控制H ₂ S气体出口浓度（[H ₂S] _out）。在这项工作中，人们致力于了解和发展在有氧条件下在生物滴滤池中去除生物H ₂ S的控制策略。经典比例和比例-积分反馈控制器被应用在用于沼气脱硫的好氧生物滴滤池模型中。研究了两个不同的控制回路：（i）基于AFR调节来控制[O ₂ ] _out的AFR闭环，以及（ii）基于TLV调节来控制[H ₂ S] _out的TLV闭环。AFR调节跨度限制为一定值，以便与沼气稀释因子相对应，该因子将使沼气混合物中的甲烷含量最小，远低于获得爆炸性混合物所需的值。最小TLV为5.9 mh ^-1，以向填充床提供营养和水分，最大TLV为28.3 mh ^-1，以防止生物滴滤池（BTF）泛滥。通过从2000 ppm _v到6000 ppm _v的逐步增加，以及从61.5 L h ^-1（EBRT = 118 s）到184.5 L h ^-1的逐步增加，对沼气流量的变化进行评估（EBRT = 48.4 s）。控制器参数是根据时间积分准则和简单准则（例如稳定性和振荡控制器响应）确定的。在实施控制策略之前，对两种不同的传质相关性进行了评估，以研究可操纵变量的影响。还研究了开环行为，以确定控制策略对过程性能变量（如去除效率，硫酸盐和硫的选择性以及氧气消耗）的影响。AFR法规有效地控制了[O ₂ ]_排放; 然而，对过程性能参数的影响不如调节TLV来控制[H ₂ S]_时大。。这种基于模型的分析提供了有关每种策略的可控性限制以及每种策略可能对流程性能产生影响的有价值的信息。