在厭氧發(fā)酵沼氣處理過(guò)程中，含硫化合物會(huì)被轉(zhuǎn)化為H2S，沼氣中H2S的含量在幾百毫克到幾十克/Nm3不等，對(duì)管道、金屬設(shè)備、燃燒器以及儀器、儀表都有很強(qiáng)腐蝕性，因此，影響了沼氣綜合利用。我國(guó)環(huán)保標(biāo)準(zhǔn)規(guī)定，利用沼氣能源時(shí)，沼氣中H2S含量不得超過(guò)20mg/Nm3,不管是工業(yè)還是民用沼氣，都需要除去，沼氣脫硫作為沼氣綜合利用中更重要的一個(gè)環(huán)節(jié)越來(lái)越受到重視。今天綜合沼氣主要的脫硫方法簡(jiǎn)單介紹一下。
In the process of anaerobic fermentation biogas treatment, sulfur compounds will be converted into H2S. The content of H2S in biogas varies from several hundred milligrams to dozens of grams / Nm3, which is very corrosive to pipelines, metal equipment, burners, instruments and meters. Therefore, it affects the comprehensive utilization of biogas. According to China's environmental protection standards, when biogas energy is used, the content of H2S in biogas shall not exceed 20mg / Nm3. No matter industrial or civil biogas, it needs to be removed. As the most important link in the comprehensive utilization of biogas, biogas desulfurization is paid more and more attention. Today, the main desulfurization methods of comprehensive biogas are briefly introduced.
一、干法脫硫
1、 Dry desulfurization
干法脫除沼氣中H2S的基本原理是把H2S氧化成硫或硫化物的一種方法，物理吸附的過(guò)程。干法脫硫設(shè)備的結(jié)構(gòu)是，在一個(gè)塔器內(nèi)放入填料，填料層裝有活性碳，氧化鐵等。沼氣以低流速?gòu)囊欢诉M(jìn)入塔器內(nèi)的填料層，H2S氧化成硫或硫化物，余留在填料層中，凈化后沼氣從塔器另一端排出。其優(yōu)點(diǎn)∶結(jié)構(gòu)簡(jiǎn)單，使用方便，工作過(guò)程無(wú)需人員值守，適合低硫化氫，低氣量，精脫硫過(guò)程。
The basic principle of removing H2S from biogas by dry method is to oxidize H2S into sulfur or sulfide, which is a process of physical adsorption. The structure of dry desulfurization equipment is to put packing in a tower, and the packing layer is filled with activated carbon, iron oxide, etc. The biogas enters the packing layer in the tower at a low flow rate from one end, and the H2S is oxidized to sulfur or sulfide, which is left in the packing layer. After purification, the biogas is discharged from the other end of the tower. Its advantages: simple structure, easy to use, no need to watch the working process, suitable for low hydrogen sulfide, low gas content, fine desulfurization process.
生物脫硫技術(shù)包括生物過(guò)濾法，生物吸附法等，其微生物種群隨環(huán)境改變而改變。在生物脫硫過(guò)程中，氧化態(tài)的含硫污染物必須先經(jīng)過(guò)生物還原作用生成H2S或硫化物，然后再經(jīng)過(guò)生物氧化過(guò)程生成單質(zhì)硫才能脫除。在大多數(shù)生物反應(yīng)器中，微生物種類以細(xì)菌為主，真菌為次，極少有酵母菌。常用的細(xì)菌是硫桿菌，屬氧化亞鐵硫桿菌，脫氮硫桿菌及排硫桿菌。更成功的代表是氧化亞鐵硫桿菌。
Biological desulfurization technology includes biofiltration, biosorption and so on. Its microbial population changes with the change of environment. In the process of biological desulfurization, the oxidized sulfur-containing pollutants must first be reduced to H2S or sulfide by biological reduction, and then to elemental sulfur by biological oxidation. In most bioreactors, the main microbial species are bacteria, followed by fungi, and few yeast. The commonly used bacteria are Thiobacillus, Thiobacillus ferrooxidans, Thiobacillus denitrifier and Thiobacillus thiooxidans. The most successful representative is Thiobacillus ferrooxidans.
生物脫硫優(yōu)點(diǎn)是∶不需要催化劑和氧化劑(空氣除外），不需要化學(xué)污泥，產(chǎn)生很少的生物污染，能耗低，回收硫效率高，過(guò)程控制要求比較高。
The advantages of biological desulfurization are: no catalyst and oxidant (except air), no chemical sludge, little biological pollution, low energy consumption, high sulfur recovery efficiency, high process control requirements.
三、濕法脫硫
3、 Wet desulfurization
目前國(guó)內(nèi)大型沼氣脫硫廠家較多采用沼氣濕法脫硫技術(shù)，其典型代表工藝有∶沼氣中H2S在含有河北品臣公司的PTS沼氣專用脫硫劑的堿性溶液中氧化成單質(zhì)硫的濕法脫硫技術(shù)，該技術(shù)流程較為簡(jiǎn)單，脫硫效率高。
At present, the domestic large-scale biogas desulfurization manufacturers mostly adopt the wet desulfurization technology of biogas. The typical representative technology is: the wet desulfurization technology of oxidation of H2S in biogas into elemental sulfur in the alkaline solution containing PTS special desulfurization agent for Biogas of Hebei Pinchen company. The technical process is relatively simple and the desulfurization efficiency is high.
1、基本原理：
1. Basic principle:
在PTS沼氣專用催化劑參于下有吸收和再生兩個(gè)過(guò)程，由于沼氣中CO2較高，為保證堿性溶液的吸收效果，一般用純堿作為堿源。其反應(yīng)式為∶
In order to ensure the absorption effect of alkaline solution, soda ash is generally used as the alkali source. The reaction formula is:
H2S的化學(xué)吸收反應(yīng)：
Chemical absorption reaction of H2S:
H2S+Na2CO3=NaHS+NaHCO3
H2S+Na2CO3=NaHS+NaHCO3
NaHS+(X-1)S+NaHCO3=Na2Sx+CO2+H2O
NaHS+(X-1)S+NaHCO3=Na2Sx+CO2+H2O
催化氧化析硫反應(yīng)：
Catalytic oxidation sulfur evolution reaction:
2NaHS+O2 =2NaOH+2S（品臣PTS催化劑的作用下）
2nahs + O2 = 2naoh + 2S (under the action of Pinchen PTS catalyst)
2、主要流程
2. Main process
含硫沼氣從脫硫塔底部進(jìn)入，與堿性脫硫液逆流接觸。硫化氫被溶液吸收，凈化沼氣從塔頂排出。吸收硫化氫的脫硫液為富液，經(jīng)富液槽用富液泵加壓送至再生槽與空氣混合。其中硫以硫泡沫的形式浮選出來(lái)。再生后的脫硫貧液進(jìn)入貧液槽，經(jīng)泵循環(huán)進(jìn)入脫硫塔使用。
The sulfur-containing biogas enters from the bottom of the desulfurization tower and contacts with the alkaline desulfurization liquid in reverse flow. Hydrogen sulfide is absorbed by the solution and purified biogas is discharged from the top of the tower. The desulfurizing liquid absorbing hydrogen sulfide is rich liquid, which is pressurized by rich liquid pump through rich liquid tank and sent to regeneration tank for mixing with air. Sulfur is floatation in the form of sulfur foam. The regenerated desulfurized lean liquid enters into the lean liquid tank and circulates into the desulfurizing tower for use through the pump.
3、主要工藝指標(biāo)控制
3. Main process index control
總堿度18﹣25g/L
Total alkalinity 18-25g / L
溶液PH值8.2﹣8.5
PH value of solution 8.2-8.5
PTS沼氣專用濃度20﹣35ppm
Special concentration of PTS biogas 20-35ppm
脫硫液溫度35﹣40℃
Desulfurization liquid temperature 35-40 ℃
沼氣脫硫技術(shù)發(fā)展相對(duì)較成熟，根據(jù)實(shí)際情況選擇合適的產(chǎn)品。但每種方法都有自己的特點(diǎn)和適應(yīng)條件。實(shí)現(xiàn)沼氣循環(huán)綜合利用，提高沼氣脫硫效率，加強(qiáng)沼氣工程新技術(shù)和新設(shè)備研發(fā)從而降低工程成本，一直是我們的努力方向。
The development of biogas desulfurization technology is relatively mature, and appropriate products are selected according to the actual situation. But each method has its own characteristics and adaptive conditions. To realize the comprehensive utilization of biogas cycle, improve the efficiency of biogas desulfurization, strengthen the research and development of new technology and equipment of biogas engineering, so as to reduce the engineering cost, has always been our efforts.
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2020-06-19
