生物脫硫系統(tǒng)的目的在于降低沼氣中的硫化氫含量。硫化氫在燃燒過程中轉(zhuǎn)化成二氧化硫，對環(huán)境造成污染。大氣污染物控制標(biāo)準(zhǔn)中明確規(guī)定了污染物排放到大氣中的極限含量值：硫化氫4mg/m?，二氧化硫15mg/m?（德國TA-Luft標(biāo)準(zhǔn)）一般來說，當(dāng)排放1500ppm的硫化氫時，將相當(dāng)于產(chǎn)生4250mg/m?二氧化硫，應(yīng)該先脫硫再進(jìn)行沼氣能源利用。

The purpose of a biological desulfurization system is to reduce the hydrogen sulfide content in biogas. Hydrogen sulfide is converted into sulfur dioxide during combustion, causing environmental pollution. The air pollution control standards clearly specify the limit content value of pollutants emitted into the atmosphere: hydrogen sulfide 4mg/m?, Sulfur dioxide 15mg/m? Generally speaking, when emitting 1500ppm of hydrogen sulfide, it is equivalent to producing 4250mg/m according to the German TA Luft standard? Sulfur dioxide should be desulfurized first before biogas energy utilization.

一般常規(guī)的沼氣鍋爐、沼氣發(fā)電機(jī)組，對H2S的進(jìn)氣濃度要求是200ppm（或300mg/m?）。生物脫硫系統(tǒng)的作用在于使沼氣中的硫化氫含量降至300mg/m?(200ppm)，以此來避免硫化氫對后續(xù)沼氣利用設(shè)備（如發(fā)電機(jī)、鍋爐等）的腐蝕作用。通過脫硫塔凈化后的沼氣相對濕度為100%（絕對濕度約為40g水/m?），溫度介于29-38℃之間。因此，生物脫硫后的沼氣，應(yīng)考慮適當(dāng)?shù)睦淠笫占欧爬淠?，或另行設(shè)置冷干、增壓處理。

Generally, conventional biogas boilers and biogas generators require an inlet H2S concentration of 200ppm (or 300mg/m?). The function of a biological desulfurization system is to reduce the hydrogen sulfide content in biogas to 300mg/m? (200ppm) to avoid the corrosive effect of hydrogen sulfide on subsequent biogas utilization equipment (such as generators, boilers, etc.). The relative humidity of the purified biogas through the desulfurization tower is 100% (absolute humidity is about 40g water/m?), and the temperature ranges from 29 to 38 ℃. Therefore, for the biogas after biological desulfurization, appropriate condensation should be considered to collect and discharge condensate water, or separate cold drying and pressurization treatment should be set up.

脫硫系統(tǒng)一個主要特點是專屬性—即僅僅去除沼氣中的硫化氫，而不會去除其它成分。生物脫硫運行的同時，沼氣中的二氧化碳含量也因此降低。沼氣的質(zhì)量提高，排放到大氣中的二氧化碳便相應(yīng)減少。在脫硫過程中，利用不同氣體成分的溶解性和可降解性差異分離硫化氫。例如：甲烷作為沼氣的主要成分，在25℃時的亨利系數(shù)（氣體在水中的溶解度）比硫化氫低80倍。

A major characteristic of desulfurization systems is their specificity - that is, they only remove hydrogen sulfide from biogas without removing other components. During the operation of biological desulfurization, the carbon dioxide content in biogas also decreases as a result. The improvement of biogas quality leads to a corresponding reduction in carbon dioxide emissions into the atmosphere. During the desulfurization process, hydrogen sulfide is separated by utilizing the differences in solubility and degradability of different gas components. For example, methane, as the main component of biogas, has a Henry's coefficient (solubility of gas in water) 80 times lower than hydrogen sulfide at 25 ℃.

脫硫桿菌是以二氧化碳為碳源，因此導(dǎo)致了沼氣中二氧化碳含量適當(dāng)降低。然而脫硫過程中需要補(bǔ)充氧氣，沼氣中的甲烷隨著空氣中氮氣的加入而下降，粗略的估算可以按照甲烷濃度下降10%，以及總的氣量增加10%來做初步估算。

Desulfurization bacteria use carbon dioxide as a carbon source, which leads to an appropriate reduction in the carbon dioxide content in biogas. However, during the desulfurization process, oxygen needs to be supplemented, and the methane in biogas decreases with the addition of nitrogen in the air. A rough estimate can be made based on a 10% decrease in methane concentration and a 10% increase in total gas volume.

生物脫硫的工作機(jī)理描述如下：將一定量的空氣導(dǎo)入含有硫化氫的沼氣中，在反應(yīng)器內(nèi)裝有大量的生物填料，它們?yōu)榧?xì)菌繁殖提供充分的空間。塔體采用滴濾形式，系統(tǒng)水和營養(yǎng)液(NPK)不斷循環(huán)滴濾，使得填料保持潮濕狀態(tài)，并補(bǔ)充細(xì)菌生長繁殖所需營養(yǎng)。專屬絲硫菌屬、硫桿菌屬在新陳代謝的過程中吸收硫化氫，并將硫化氫轉(zhuǎn)化為單質(zhì)硫，并進(jìn)一步氧化為硫酸。

The working mechanism of biological desulfurization is described as follows: a certain amount of air is introduced into biogas containing hydrogen sulfide, and a large amount of biological fillers are installed in the reactor, providing sufficient space for bacterial reproduction. The tower body adopts a drip filtration form, and the system water and nutrient solution (NPK) continuously circulate for drip filtration, keeping the filling material moist and supplementing the nutrients required for bacterial growth and reproduction. Exclusive sulfur bacteria and sulfur bacteria absorb hydrogen sulfide during metabolism, convert it into elemental sulfur, and further oxidize it to sulfuric acid.

化學(xué)反應(yīng)式如下：

The chemical reaction formula is as follows:

H2S + 2O2 → H2SO4

H2S+2O2 → H2SO4

2 H2S + O2 → 2 S + 2 H2O

2 H2S+O2 → 2 S+2 H2O

S +  H2O + 1.5 O2 → H2SO4

S+H2O+1.5 O2 → H2SO4

反應(yīng)生成的稀硫酸在營養(yǎng)液的緩沖中和作用下，與營養(yǎng)液一起排出系統(tǒng)，此過程周而復(fù)始。

The dilute sulfuric acid generated by the reaction is buffered and neutralized by the nutrient solution, and is discharged from the system together with the nutrient solution. This process repeats itself.