The gaseous compound, hydrogen sulfide (written as H2S), is a hazardous byproduct of many biological và industrial processes including the creation of biogas. It’s usually critical to lớn separate the H2S gas from desirable or less hazardous gasses before they can be further refined. This is not, however, a simple matter. Fortunately, modern techniques are making it easier và more economical to lớn eliminate hydrogen sulfide from other gaseous products.
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WHAT IS HYDROGEN SULFIDE?
As its chemical formula suggests, H2S is composed of two hydrogen atoms and one sulfur atom. At room temperature, it manifests as a colorless gas with a characteristic “rotten-egg” odor. More critically, hydrogen sulfide is highly flammable & is toxic if inhaled. Once released into the atmosphere, it combines with oxygen to size one of the major components of acid rain.
Hydrogen sulfide is released from natural sources such as hot springs và volcanic hotspots. It is also a byproduct of the anaerobic bacteria that break down organic matter in the absence of oxygen. This means H2S shows up in significant quantities in the guts of herbivores lượt thích cows, in landfills và wastewater treatment facilities, và even in poorly aerated swamps or peat bogs. The latter is the reason that hydrogen sulfide occurs in natural gas và crude petroleum – those products were simply buried plant life from millions of years ago.
H2S is also a byproduct of some industrial processes. For many years this undesirable gas was either released or flared off along with methane, but that practice led khổng lồ the dangerous rise in acidic rain that took a concerted international regulatory effort to control.
Even if contained, H2S poses risks lớn onsite workers. Though it initially smells strongly of rotten eggs, the gas can quickly overwhelm the brain’s olfactory center. Even short-term exposure khổng lồ high concentrations can render a person unable lớn detect it without special equipment. & since H2S is heavier than air, it tends lớn accumulate in poorly ventilated areas. Breathing highly concentrated hydrogen sulfide can lead lớn quick incapacitation & permanent lung and brain damage.
As if that weren’t enough, the byproducts created by H2S combustion are corrosive. Though it is often associated with methane fuels, hydrogen sulfide will damage power nguồn generators if it is not first removed from the fuel gasses.
Nowadays, most industrial H2S is required to lớn be scrubbed out before waste products can be safely used or released.
H2S REMOVAL
Unfortunately, separating H2S from other, more useful gasses like methane is not as simple as running it through a filter. The hydrogen sulfide must chemically adhere to some other material and precipitate out of the gas mixture.
For decades, the most common extraction truyền thông has been composed of iron oxide (FeO). The raw output đầu ra gas is passed through beds of FeO pellets. This gives the H2S an opportunity to lớn bind to lớn the truyền thông before the gas is forwarded to lớn more delicate equipment.
Unfortunately, this traditional process is quite inefficient, so a significant amount of removal truyền thông is required in order lớn extract much H2S. Additionally, iron oxide gets saturated quickly, so it must be replaced often.
Improved H2S removal options were clearly needed. Extensive research và experimentation ultimately yielded a product called FerroSorp which improved on nearly every one of the old FeO’s performance statistics.
FERROSORP H2S REMOVAL MEDIA
FerroSorp is based around iron oxide-hydroxide, or FeO(OH). In contrast lớn its simpler cousin, this iron hydroxide formula can absorb far more H2S per unit volume và does so at a higher rate. Even so, it does not get saturated nearly as quickly, so beds of FerroSorp can remain in place up khổng lồ three times as long as traditional FeO. The FerroSorp material is also less dense, which confers a dual benefit; it is easier khổng lồ transport than FeO media, & it offers more surface area onto which the hydrogen sulfide can adhere.
Following the initial capture of H2S, the loaded FerroSorp will undergo a secondary “regeneration” reaction as long as enough moisture và oxygen is present in the surrounding air. The H2O & O2will ultimately replace the sulfur in binding with FerroSorp’s iron atoms, after which the sulfur itself is left in a powdery elemental form. The regenerated iron hydroxide can then once again bind with new hydrogen sulfide molecules, extending its useful lifetime.
As with any chemical removal media, FerroSorp does eventually become saturated to lớn the point where it can no longer be regenerated. Fortunately, since FerroSorp converts the hydrogen sulfide into relatively harmless elemental sulfur, it is easy và inexpensive to dispose of. The FerroSorp & its byproducts are environmentally nontoxic.
FERROSORP MODE OF OPERATION
FerroSorp undergoes two distinct reactions when it encounters hydrogen sulfide. First is the initial absorption reaction:
Absorption:2 Fe(OH)3+ 3 H2S → Fe2S3+ 6 H2O– 62 kJ/mol
Note that the above equation assumes the FerroSorp’s active iron hydroxide has already encountered enough moisture lớn convert it into Fe(OH)3. Three moles of water vapor are required per mole of iron hydroxide in order to prep it. Without this moisture, the FerroSorp will still absorb H2S, but at a far less efficient rate.
Following the absorption phase, the loaded FerroSorp will typically undergo a secondary regeneration reaction:
Regeneration:Fe2S3+ 1½ O2+ 3 H2O → 2 Fe(OH)3+ 3 S– 603 kJ/mol
Regeneration will naturally take place as long as there is enough water vapor and không lấy phí oxygen available around the FerroSorp bed. As the iron hydroxide is restored to lớn its original form, molecular sulfur precipitates out as a powdery coating on the FerroSorp pellets.
The two reactions combined can be expressed as:
3 H2S + 1½ O2→ 3/8 S8+ 3 H2O∆G° = – 665 kJ/mol
It must be noted that both reactions are exothermic, & the regeneration reaction gives off about ten times as much energy as the absorption one. Temperatures around the FerroSorp bed must be monitored for safety purposes; in the presence of oxygen, sulfur can ignite above temperatures of 190° Celsius (374° Fahrenheit).
MOISTURE
As mentioned above, the moisture màn chơi in the gas stream plays a significant role in the hydrogen sulfide removal process. A minimum water moisture màn chơi of 40% is necessary to keep the reaction as efficient as possible. The hydrogen sulfide will ionize as it interacts with H2O in the gas stream. Ionization primes the sulfur content to bond quickly with the removal media’s iron atoms.
Not every gas stream in need of purification is the same, of course. Some have outputs with exceedingly high moisture nội dung while others are much drier. Naturally, it’s rare for one sản phẩm to deal well with all situations. To accommodate various site needs, there are two versions of FerroSorp, designed khổng lồ be used at different relative humidity levels. FerroSorp SD works best in 40%-60% humidity gas streams while FerroSorp SK is designed for 60%-100% levels.
OXYGEN LEVELS
Because không tính phí oxygen is an important part of the regeneration reaction as well, it also must be present in the right quantities to promote maximum H2S removal rates. If a concentration of 1000 ppm H2S must be removed, 0.2%-0.4% oxygen in the gas stream will help to lớn yield the maximum removal rates. It can be injected into the gas stream as pure O2or ambient air can be used. In the case of the latter, between 1% và 2% of air would be sufficient.
Removal of higher H2S concentrations, of course, requires higher concentrations of oxygen. Your O2input should be tailored lớn your specific H2S requirement.
CONSTANT SYSTEM PRESSURE
Some H2S removal solutions tend to expand and clump up as they extract hydrogen sulfide from the gas. This can cause the pre-filtration pressure to rise as the truyền thông becomes increasingly saturated.
The presence of the pellet bed does, of course, have some effect on the overall system pressure. Interra Global has tested a range of flow rates lớn help customers estimate the expected pressure drop. But over the life of any given batch of pellets, you can expect this pressure differential to lớn remain effectively constant.
DISPOSAL
Though the FerroSorp pellets last longer than other H2S removal media, they will eventually become saturated. A powdery grey coating of sulfur precipitate will develop on the pellets và eventually prevent new H2S from reaching the iron hydroxide surface. Once it gets to lớn this point, the batch of pellets needs khổng lồ be replaced.
FerroSorp truyền thông media is less dense than other iron oxide media, so it is easier to handle and transport. As long as it has not encountered much in the way of liquids, the expended pellets can be easily vacuumed out of their bed.
A dust mask, safety glasses, và gloves are recommended when handling the media. This is particularly important for the saturated pellets because the sulfurous dust that collects on their surfaces is easily brushed off. The sulfur is environmentally nontoxic but is not good for the lungs or eyes.
The spent FerroSorp truyền thông does not require hazardous-material handling during transport or disposal. Many landfills that accept household waste will also readily take the FerroSorp.
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FERROSORP BENEFITS AT A GLANCE
FerroSorp is superior to other existing hydrogen sulfide removal methods in nearly every metric. In summary of its advantages:
FerroSorp’s H2S removal loading rates far exceed any similar product. It can be expected to absorb >40% by weight when properly configured.Iron hydroxide is the highest-purity iron compound that functions as an H2S removal agent.Properly employed, FerroSorp brings the outlet H2S concentration down to safe levels, ensuring that it meets or exceeds strict environmental regulations.The regeneration reaction helps FerroSorp last longer. Case studies indicate that the same volume remains effective 2.5-3 times as long as competing media.Users experience less caking/clumping than with other media. This makes FerroSorp easier khổng lồ change out, reducing maintenance time & costs.Under most site specific local regulations, loaded pellets are environmentally nontoxic. No post-processing is needed, so disposal is simple & inexpensive.Pre- and post-purification pressures bởi not vary significantly over the life of the media. Because FerroSorp pellets vì not expand or cake up as they extract H2S, they don’t create a significant pressure differential.Minimal maintenance is needed between changeouts. FerroSorp requires no daily water sprays lượt thích some media, so no water disposal or treatment is necessary.If you’re in an industry that produces methane in any form, you probably know all too well the challenges of hydrogen sulfide removal. FerroSorp has proven itself lớn be the most efficient & cost-effective H2S removal truyền thông media on the market. As North America’s FerroSorp provider, Interra Global can answer any further questions you may have on its use. Tương tác us today at:
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