沼氣中的硫主要以H2S形式存在,所含有機硫較少。脫除硫化氫的方法很多,一般可分為干法脫硫、濕法脫硫和生物脫硫。
The sulfur in biogas mainly exists in the form of H2S and contains less organic sulfur. There are many methods for removing hydrogen sulfide, which can generally be divided into dry desulfurization, wet desulfurization, and biological desulfurization.
干法脫硫通常用于低含硫氣體處理,特別是用于氣體精細(xì)脫硫。大部分干法脫硫工藝由于需要更換脫硫劑而不能繼續(xù)操作,還有一些干法如錳礦法、氧化鋅法、氧化鐵、活性炭等,脫硫劑不能再生或再生次數(shù)很少,脫硫飽和后要廢棄,這樣一方面會造成環(huán)境問題,另一方面會增加脫硫成本。
Dry desulfurization is commonly used for low sulfur gas treatment, especially for fine gas desulfurization. Most dry desulfurization processes cannot continue to operate due to the need to replace the desulfurizer. There are also some dry methods such as manganese ore method, zinc oxide method, iron oxide, activated carbon, etc. The desulfurizer cannot be regenerated or the regeneration frequency is very small. After desulfurization saturation, it needs to be discarded. This will cause environmental problems on the one hand and increase desulfurization costs on the other hand.
濕法脫硫是利用特定的溶劑與氣體逆流接觸而脫除其中的H2S,溶劑通過再生后重新進(jìn)行吸收,根據(jù)吸收機理的不同,又分為化學(xué)吸收法、物理吸收法、物理化學(xué)吸收法以及濕式氧化法。濕式氧化法脫硫效率高,單質(zhì)硫可回收,流程較簡單,大多數(shù)脫硫劑可以再生,運行成本低等;同時該法流程復(fù)雜、投資大、適用于氣體處理量大,H2S含量高的場合。
Wet desulfurization is the process of using a specific solvent to remove H2S through countercurrent contact with gas. The solvent is regenerated and reabsorbed, which can be further divided into chemical absorption, physical absorption, physicochemical absorption, and wet oxidation based on different absorption mechanisms. Wet oxidation method has high desulfurization efficiency, recyclable elemental sulfur, simple process, most desulfurizers can be regenerated, and low operating cost; At the same time, this method has a complex process, high investment, and is suitable for situations with large gas processing capacity and high H2S content.
生物脫硫系統(tǒng)以各種微生物的容納力為基礎(chǔ),利用微生物的生命活動將有機污染轉(zhuǎn)化為對人體健康和生態(tài)環(huán)境無害的化合物、生物法常用于污水處理工程中產(chǎn)生的硫化物。生物脫硫技術(shù)包括生物過濾法、生物吸附法和生物滴濾法,三種系統(tǒng)均屬開放系統(tǒng),其微生物種群隨環(huán)境改變而變化。在生物脫硫過程中,氧化態(tài)的含硫污染物必須先經(jīng)生物還原作用生成硫化物或H2S,然后再經(jīng)生物氧化過程生成單質(zhì)硫,才能去除。
The biological desulfurization system is based on the capacity of various microorganisms, utilizing their life activities to transform organic pollution into compounds that are harmless to human health and the ecological environment. Sulfides are commonly produced in wastewater treatment projects through biological methods. Biological desulfurization technology includes biological filtration, biological adsorption, and biological drip filtration, all of which belong to open systems, and their microbial populations change with environmental changes. In the process of biological desulfurization, oxidized sulfur-containing pollutants must first undergo biological reduction to generate sulfides or H2S, and then undergo biological oxidation to generate elemental sulfur in order to be removed.
生物凈化工藝與上述傳統(tǒng)工藝相比具有運行成本低、反應(yīng)條件溫和、能耗少和有效減少環(huán)境污染等優(yōu)點,但脫硫微生物都是需要氧型的,氧氣或空氣的加入可能會導(dǎo)致沼氣中氧含量上升影響沼氣的安全性,因此采用生物脫硫是要時刻監(jiān)控反應(yīng)器中的氧含量。
Compared with the traditional processes mentioned above, biological purification processes have advantages such as low operating costs, mild reaction conditions, low energy consumption, and effective reduction of environmental pollution. However, desulfurization microorganisms require oxygen, and the addition of oxygen or air may lead to an increase in oxygen content in biogas, affecting the safety of biogas. Therefore, the use of biological desulfurization requires constant monitoring of the oxygen content in the reactor.