Pellet vs. Honeycomb Activated Carbon for VOCs Control

Volatile organic compounds, commonly known as VOCs, are released by many industrial processes, including painting, printing, chemical manufacturing, pharmaceutical production, electronics manufacturing, furniture finishing, rubber processing, and solvent handling. Because these compounds may cause odors, affect air quality, and contribute to regulatory compliance problems, industrial facilities need reliable VOCs control systems.

活性炭吸附是工业废气 VOCs 治理中应用最广泛的技术之一，工艺相对简单、适用面广，可捕集多种有机蒸气。但吸附系统的性能在很大程度上取决于活性炭的形态与特性。

Two common choices are pellet activated carbon and honeycomb activated carbon. Both materials remove VOCs molecules through adsorption, but their physical structures create important differences in adsorption capacity, airflow resistance, mechanical strength, energy consumption, installation, and maintenance.

Choosing between pellet and honeycomb activated carbon should therefore involve more than comparing iodine numbers or purchase prices. Engineers must consider airflow, VOCs concentration, contaminant composition, temperature, humidity, particulate loading, pressure-drop limitations, and the intended operating method of the adsorption system.

什么是颗粒活性炭？

颗粒活性炭是一种成型炭产品，通常制成圆柱状，也常被称为挤压炭或柱状活性炭。

厂家以煤、木材、椰壳等富碳原料制粒：经炭化、活化、粉碎，必要时加入粘结剂混合，再挤压成直径较均匀的圆柱体。常见工业规格有 3 mm、4 mm、5 mm，也可提供更小或更大尺寸。

The finished pellets are loaded into fixed-bed adsorbers, carbon filter boxes, or replaceable vessels. As VOCs-contaminated air passes through the spaces between the pellets, organic molecules move from the gas stream toward the carbon surface and diffuse into the internal pore structure.

When the carbon bed approaches its breakthrough point, the pellets must be replaced or regenerated. Regeneration methods may include steam, heated air, inert gas, vacuum desorption, or off-site thermal reactivation, depending on the VOCs, equipment design, and recovery requirements.

颗粒活性炭通常单位床层体积的炭质量较高，厂家还可针对不同气相应用调整其孔隙结构与表面化学性质。优质颗粒机械强度好，在运输、装填和运行过程中粉尘较少。

According to Calgon Carbon, pelletized activated carbon is commonly used for vapor-phase purification, VOCs abatement, solvent recovery, odor control, and air treatment. Its consistent shape can also provide lower pressure drop than irregular granular carbon under comparable conditions. Calgon Carbon 颗粒活性炭资料

不过，颗粒床层的气流路径相对复杂：空气必须穿过颗粒之间大量细小而不规则的间隙。当床层较深、颗粒直径较小、气速较高或系统内积炭粉时，压降会升高。

什么是蜂窝活性炭？

蜂窝活性炭是一种结构化吸附材料，内部含有大量平行通道。通常将活性炭粉与粘结剂及其他功能材料混合后，通过蜂窝状模具挤压成型。

The result is a rigid block with a large number of straight passages. VOCs-contaminated air flows through these channels while organic molecules diffuse toward the activated carbon walls and enter the internal pore network.

直通孔道设计赋予蜂窝活性炭最突出的工程优势——气流阻力低。与常规填充床相比，蜂窝结构可在较低压降下让大量空气通过吸附剂。

对整体式活性炭的研究表明，在压降限制严格的场合处理大风量气体时，开孔通道结构尤为适用。 《Microporous and Mesoporous Materials》研究摘要

蜂窝块还便于模块化安装，可在吸附箱内按层或按格排列，更换比卸出散装颗粒更为简便。由于炭被固定在固体结构中，材料位移与粉尘产生也相应减少。

但蜂窝炭的性能取决于多项制造参数，包括含炭量、粘结剂比例、孔道密度、壁厚、活化程度、孔径分布与抗压强度。粘结剂比例过高虽可提高结构强度，却会占据孔容或稀释有效炭含量。

颗粒炭与蜂窝炭的主要区别

上述特征反映的是一般工程趋势，并不意味着所有颗粒炭产品的吸附容量都更高，也不意味着所有蜂窝炭的运行阻力都更低。实际性能取决于炭的品质、设备构造、床层尺寸、气速与工艺条件。

Which Type Has a Higher VOCs Adsorption Capacity?

吸附容量不能仅凭形态判断。

The VOCs adsorption performance of activated carbon depends on its micropore and mesopore distribution, internal surface area, surface chemistry, raw material, degree of activation, and compatibility with the target compound. Operating conditions such as VOCs concentration, temperature, humidity, contact time, and the presence of competing contaminants are also important.

Iodine number is frequently used as a general activated carbon quality indicator. However, it mainly reflects the adsorption of relatively small molecules and does not directly predict dynamic adsorption performance for every VOCs.

甲苯、二甲苯、乙酸乙酯、丙酮、二氯甲烷等工业 VOCs 在分子尺寸、极性、沸点与蒸气压上各不相同，因此同一种活性炭对不同有机物的穿透容量可能相差很大。

For VOCs projects, more useful selection data may include:

• Dynamic adsorption capacity for the target VOCs;
• 代表性工况下的穿透曲线；
• 四氯化碳吸附率；
• 苯或丁烷吸附性能；
• 孔径分布；
• 堆密度；
• 机械强度；
• 水分含量；
• 再生后的性能。

在相同设备容积内，颗粒床层通常装填的活性炭质量更大，只要型号与床层深度选择得当，可获得较长的穿透周期。蜂窝炭则以部分材料体积换取贯通的空气通道，从而降低压降、便于操作。

不过，制造精良的蜂窝炭产品也可能优于低品质颗粒炭产品。材料形态永远不能替代产品检测与充分的工程评估。

何时应选用颗粒活性炭？

在以下情况下，颗粒活性炭通常是合适的选择：

1. The exhaust flow is low or moderate, while the VOCs mass loading is relatively high.
2. 工艺要求较长的穿透时间或较高的工作容量。
3. The VOCs composition is known, allowing the pore structure to be matched to the target compounds.
4. 系统采用固定吸附床、蒸汽再生或溶剂回收工艺。
5. 风机与管道系统能够承受预期的床层压降。
6. 活性炭需能承受装填、卸料、运输与多次再生。
7. 针对特定污染物需要使用浸渍活性炭。

颗粒炭常用于溶剂回收，因为可用于工程化再生系统。但活性炭、脱附方式、罐体设计与回收溶剂处理工艺必须相互匹配。

化学浸渍颗粒炭可改善对普通物理吸附难以高效捕集的某些化合物的去除效果。浸渍剂应根据目标污染物的化学性质选择，而不能视为通用的性能提升手段。

何时应选用蜂窝活性炭？

在以下情形中，蜂窝活性炭往往更受青睐：

1. The exhaust volume is high and the VOCs concentration is relatively low.
2. 现有风机可用静压有限。
3. 通风系统连续运行，风机能耗是主要关注点。
4. 可用安装空间受限。
5. 需要模块化安装与更快捷的换炭。
6. 气体已先经有效的除尘、除雾和除液设备处理。
7. 项目需要紧凑、低气流阻力的吸附器。

在大风量通风与涂装作业中，蜂窝炭尤具吸引力。其低压降结构可减轻排风机的附加负荷。

Correct module sealing is essential. Gaps between blocks or between the blocks and the equipment housing can allow untreated gas to bypass the adsorbent. Poor sealing may therefore reduce overall VOCs removal even when the honeycomb carbon itself has good adsorption properties.

How Do Temperature, Humidity, and Dust Affect VOCs Adsorption?

颗粒炭与蜂窝炭都要求合适的进气条件。

Physical adsorption is generally favored by lower temperatures. When the inlet temperature rises, adsorption capacity may decrease, and previously captured compounds may desorb more easily. The heat released during adsorption can also raise the temperature inside the carbon bed, especially when VOCs concentrations fluctuate or become unexpectedly high.

Moisture may compete with some VOCs for pore volume and adsorption sites. The severity of this effect depends on the surface properties of the carbon, the VOCs species, concentration, temperature, and relative humidity. For this reason, one universal humidity limit should not be applied to every activated carbon and every VOCs mixture.

The US Environmental Protection Agency identifies outlet VOCs concentration, regeneration conditions, carbon activity, bed temperature, inlet temperature, airflow, inlet concentration, pressure differential, moisture content, and leakage as relevant indicators of carbon adsorber performance. US EPA 活性炭吸附器技术指南

粉尘、漆雾、油滴与冷凝液会堵塞活性炭的外表面或内部孔隙，还会增大系统压降并造成气流分布不均。

蜂窝炭对孔道堵塞尤为敏感，而颗粒床层可能出现表面堵塞或局部流路。因此工业涂装系统应在吸附段之前设置合适的预处理，如干式过滤、除雾或冷凝控制。

选择活性炭前应核查哪些参数？

A reliable VOCs control design should evaluate at least the following information:

• 实际风量及预期波动范围；
• Inlet VOCs concentration and required outlet concentration;
• VOCs mass flow rate;
• Individual VOCs species and their proportions;
• 废气温度与相对湿度；
• 粉尘、油雾、漆雾与液滴含量；
• 相关测试条件下的动态吸附容量；
• 风机可用压力与可接受的系统压降；
• 气速与空床接触时间；
• 预期穿透时间；
• 换炭或再生频次；
• 再生方式及再生后的容量；
• Bed temperature, pressure-drop, and outlet VOCs monitoring;
• 防火与温度控制；
• 废炭运输、再生与处置要求。

设计人员还应区分饱和容量、穿透容量与工作容量。

Saturation capacity represents the maximum amount of contaminant the carbon can hold under specified equilibrium conditions. An industrial adsorber, however, usually has to be switched, regenerated, or replaced before substantial VOCs breakthrough occurs.

在再生系统中，工作容量指每次运行周期内、考虑再生后残留在炭上的物质之后，实际可吸附的量。因此，动态穿透容量与工作容量通常比实验室最大吸附值更有助于设备设计。

哪种更经济？

每公斤或每立方的采购价格并不能完整反映成本对比。

颗粒活性炭可提供较好的床层容量，但压降会增大风机能耗；卸料、装填、粉尘控制与停产同样构成运行成本。

蜂窝活性炭可降低压降、简化更换。但若有效含炭量低、活化不足、机械强度差或尺寸精度不佳，则可能需要更频繁地更换。模块密封不良造成的气流旁通也会降低处理效率。

客观的经济性比较应包括：

• 吸附设备投资；
• 活性炭采购成本；
• 每次更换的用炭量；
• 预期使用寿命；
• 风机电耗；
• 人工与停机；
• 再生费用；
• 废炭运输与处置；
• 预处理维护；
• 监测要求；
• 合规风险。

For high-airflow, low-concentration VOCs exhaust, honeycomb activated carbon often provides practical advantages through lower pressure drop and reduced ventilation energy demand. For processes requiring greater bed capacity, targeted adsorption, or solvent recovery, pellet activated carbon may be the stronger candidate.

颗粒炭还是蜂窝炭：最终选型建议

Neither pellet nor honeycomb activated carbon is the best choice for every VOCs control project.

颗粒活性炭孔隙结构可调、装炭量较高、机械强度良好，适合深度固定床吸附。当吸附容量、特定污染物去除效果、再生或溶剂回收是首要考虑时，常选用此类产品。

蜂窝活性炭具有直通气流通道、压降低、模块化搬运与紧凑安装的特点，常用于风机能力与运行能耗较为重要的大风量、低浓度工业废气系统。

The final decision should be based on the actual VOCs composition, airflow, concentration, temperature, humidity, required removal efficiency, acceptable pressure drop, and expected carbon replacement cycle. For complex or variable emissions, laboratory adsorption tests, breakthrough testing, or a controlled field trial can significantly reduce selection risk.

Activated carbon should also be evaluated as part of a complete VOCs control system rather than as an isolated material. Effective pretreatment, correct adsorber sizing, uniform airflow distribution, reliable sealing, outlet monitoring, temperature control, and timely replacement are all necessary for stable performance.

When the carbon material, equipment structure, operating conditions, and maintenance plan are properly matched, both pellet and honeycomb activated carbon can provide reliable and economical VOCs control.