H2S Scrubber: Design, Operational Principles, Packed Bed Systems, Tank Solutions, and Types of Media

Author: Michael Klepik, Chief Executive Officer

Hydrogen sulfide emissions come from various industrial sources across several sectors:

• In the oil and gas industry, it is released during the extraction and refining of oil and natural gas, especially through hydrodesulfurization.
• In the chemical industry, it is a byproduct of sulfuric acid and sulfur dioxide production.
• The pulp and paper sector generates it during wood pulp cooking, particularly with the sulfate method.
• In metallurgy, it is emitted during the roasting of ores and metal processing.
• Biogas facilities produce it as a byproduct of anaerobic digestion.
• Wastewater treatment plants and sewer systems release it from anaerobic decomposition of organic matter.
• Coke plants release it during coal pyrolysis.
• The textile manufacturing emits it in dye production.

The toxicity and corrosiveness of substances require strict monitoring. While detectable by its rotten egg smell, olfactory adaptation makes it unreliable for safety. Low exposure causes irritation and nausea, while high exposure leads to poisoning. It can also damage equipment through corrosion.

4. The next step in the hydrogen sulfide scrubber design involves calculating hydrodynamic characteristics such as airflow and liquid velocities, as well as the mass transfer coefficient. This coefficient represents the rate of mass transfer between the phases during contaminant absorption and is crucial for achieving the required purification efficiency. Based on these calculations, the optimal height of the bulk layer is determined.
5. Furthermore, the necessary ratio of purification agent volume to the volume of treated air must be determined. This ratio can depend on the inlet and outlet concentrations of the pollutant and the reaction rate with the absorbent. The calculation of the required absorbent flow rate to achieve the desired level of purification also relies on the type of filling used (such as Raschig rings, Berl saddles, Pall rings, Intalox rings, and others), which provide a maximum phase contact area, as well as the implementation method (structured or random, fixed-bed or floating-bed).
6. To prevent corrosion and maintain the durability of the structure, corrosion-resistant materials and purification agents are carefully selected. For instance, in H2S caustic scrubber design, stainless steel and alloyed steels are often utilized for the vessel body, while chemically resistant plastics and ceramics are commonly employed for internal components such as packing, trays, valves, fittings, and piping.
7. The engineering process also includes calculations for the discharge systems of circulating liquids also includes calculations for the discharge systems of circulating liquids.
8. Additionally, we need to clarify 'what do hydrogen sulfide scrubber products mean in terms of unit efficiency?' during our analysis. This involves evaluating how well these systems remove pollutants and comparing their performance to industry standards.
9. The final stage of H2S gas scrubber design involves ensuring ease of maintenance by providing access to internal components for cleaning and replacement.
10. It is also essential to implement a monitoring and control system, which includes pressure and temperature sensors, airflow and liquid throughput meters, pH measurement of the circulating fluid, hydrogen sulfide analyzers at both the inlet and outlet, and emergency alert systems to notify operators of any deviations in parameters.

The most effective method for removing the contaminant from dust-free industrial emissions is through a packed-bed H2S scrubber. This equipment is specifically engineered to capture unwanted impurities from industrial exhausts through a wet scrubbing method. Understanding the H2S scrubber, how it works, and its operational principles is crucial for effective industrial gas purification.

The operating principle of a wet H2S air scrubber relies on the absorption of the pollutant from the exhaust stream using a fluid absorbent. The pollutant-laden stream enters the device and passes through a bed of fill elements, where it contacts a reagent capable of binding with the contaminant. The fluid circulates within the system, ensuring continuous contact with the pollutant and maintaining optimal purification efficiency.

When using a sodium hydroxide solution—the most common liquid for the H2S scrubber — the reactions lead to the formation of sulfides and hydrosulfides, which effectively reduce the concentration of the substance in the outlet stream. To enhance the effectiveness of the process, a specialized packing layer is often employed. It increases the contact time between the phases, thereby improving the mass transfer rate. Additionally, it helps evenly distribute the fluid throughout the unit 's internal volume, minimizing the risk of flooding and ensuring a uniform stream. Consequently, the packed bed plays a crucial role in ensuring the high efficiency of the wet H2S scrubber system.

After contacting the stream, the spent liquid is collected and may undergo further treatment or disposal. An important aspect of operating a system is maintaining optimal conditions, such as temperature and pH. This is essential because the reagent employed in the fluid phase is consumed over time, and pH is one of the key indicators that signal when fresh alkali needs to be added to the scrubbing solution.

Capturing can be challenging. This difficulty arises from its low solubility in water, which limits its reaction with reagents in conventional aqueous solutions. To improve the pollutant's removal, an H2S scrubber train consisting of multiple units, each potentially using different absorbents, may be employed depending on the initial concentration of the substance in the treated stream.

If emissions contain solid particles in addition to H2S, relying solely on a bed of fill elements can diminish the efficiency of absorption. This also hinders the uniform flow of phases within the column, resulting in decreased performance. Consequently, more frequent cleaning of the device is required, leading to increased operating costs and downtime.

For streams containing solid particles, the following options for H2S scrubber technology can be considered:

• Venturi devices effectively remove both gases and fine particles at high air flow velocities.
• Cyclones employ centrifugal forces, making them suitable for pre-treatment procedures.

An H2S gas scrubber train, consisting of various types of units, may provide an optimal approach for achieving a high degree of purification.

In the oil and gas, chemical, food, and other industries, packed-bed devices are commonly employed.
Inside the unit, specialized filling materials (such as ball-type, Berl saddles, Pall rings, and others) create a large total liquid surface area, ensuring optimal contact between the air and the absorbent. The airstreams pass through these media, where pollutants are absorbed. The packing facilitates uniform liquid flow distribution, preventing the formation of "dead zones" and ensuring high efficiency. The H2S wet scrubber design can be tailored to accommodate various types of absorbents, which will be discussed in more detail below.

Our company offers an H2S scrubber for sale in various configurations:

Various types of H2S scrubber media are used in wet scrubbing devices. Let’s examine them.

As previously mentioned, water is not effective for cleaning due to its low solubility. Therefore, we will move directly to scrubbing methods with reagents.

The most commonly used reagents for chemical engineering scrubber hydrogen sulfide are sodium hydroxide (NaOH) and potassium hydroxide (KOH). Since a pollutant dissolved in water behaves as a weak acid, it can be easily neutralized by alkalis:
H₂S + NaOH_(dil.) → NaHS + H₂O
H₂S + 2NaOH_(conc.) → Na₂S + 2H₂O
H₂S + KOH_(dil.) → KHS + H₂O
H₂S + 2KOH_(conc.) → K₂S + 2H₂O

Another approach to neutralizing unwanted impurities is to leverage their strong reducing properties. By incorporating common oxidizers into the scrubbing medium, such as potassium permanganate, hydrogen peroxide, or potassium hypochlorite, the substance can be oxidized to elemental sulfur or sulfates.
3H₂S + 2KMnO₄ → 2MnO₂ + 3S + 2KOH + 2H₂O
H₂​O₂ ​+ H_2​S → S + 2H_2​O
NaOCl + H_2​S → S + NaCl + H₂​O

Additionally, solutions of monoethanolamine (MEA) or diethanolamine (DEA) are often employed, as they effectively absorb the contaminant through chemical interaction.
H₂​S + MEA → MEA-H⁺ + HS⁻
H_2​S + DEA → DEA-H⁺ + HS⁻

Hydrosulfide ions and protonated amines (MEA-H⁺ or DEA-H⁺) are generated during the process. These ions are relatively stable in aqueous solution, and the absorption efficiency increases with higher concentrations of amines in the scrubbing fluid. One of the advantages of this method is that the solution can be regenerated after the absorption of the impurities. During this process, we often inquire, "What are the byproducts of a hydrogen sulfide scrubber?" to guarantee effective waste management. The impurities are removed by raising the temperature and lowering the pressure, which allows the amines to react again afterward.

It is important to highlight that the H2S scrubber process may incorporate biological media containing microorganisms, such as Thiobacillus or Desulfovibrio. These microorganisms effectively metabolize the pollutant, converting it into less toxic compounds like sulfur or sulfates.

In the oil sector, leaks occur during the extraction or processing of hydrocarbons, where this material is generated as a byproduct. Consequently, the H2S scrubber from methane is crucial for ensuring safe gas processing in this sector. Similarly, the chemical sector faces leaks during the production of sulfur-containing compounds, such as sulfides and sulfuric acid.

In metallurgy, pollutants are generated during flotation and metal extraction. In power plants that utilize biomass or coal, it may form from the decomposition of organic matter. Wastewater treatment facilities are also at risk of the substance's leaks during anaerobic waste processing.

They are also critical in the food industry, where contaminants are generated during the decomposition of organic materials. In fertilizer production, especially those based on ammonia, the compound may arise during processing.

If your production requires the removal of sulfur compounds from exhaust streams, contact us. Our engineers will answer all your questions and assist you in selecting the appropriate equipment for your specific needs.