沼气特性概述2.1沼气来源--厌氧处理工艺链

　　Overview of Biogas Characteristics 2.1 Biogas Source - Anaerobic Treatment Process Chain

　　（1）目前造纸废水处理流程：初沉池→调节池→UASB/IC反应器→好氧处理，其中UASB反应器产气占比达70%以上；

　　(1) At present, the treatment process of papermaking wastewater is as follows: primary sedimentation tank → regulating tank → UASB/IC reactor → aerobic treatment, in which the gas production of UASB reactor accounts for more than 70%;

　　（2）造纸污泥的协同处理：造纸污泥（含纤维残渣）经中温（35-37℃）消化，产气周期15-20天，VS（挥发性固体）降解率与产气量呈正相关（VS每增加1%，产气量提升0.5m/t）；

　　(2) Collaborative treatment of papermaking sludge: papermaking sludge (including fiber residue) is digested at medium temperature (35-37 ℃), with a gas production cycle of 15-20 days. The degradation rate of volatile solids (VS) is positively correlated with gas production (for every 1% increase in VS, the gas production increases by 0.5m/t);

　　（3）原料差异性影响：废纸制浆沼气含硫量高（HS>1500ppm），原生浆沼气硫含量低（HS<800ppm）；非木浆（如竹浆）沼气甲烷含量较木浆低3-5个百分点。

　　(3) The impact of differences in raw materials: the sulfur content of waste paper pulp biogas is high (H-S>1500ppm), while the sulfur content of primary pulp biogas is low (H-S<800ppm); The methane content of non wood pulp (such as bamboo pulp) biogas is 3-5 percentage points lower than that of wood pulp.

　　2.2沼气成分与热值的动态分析

　　2.2 Dynamic analysis of biogas composition and calorific value

　　（1）硫化氢处理必要性：HS浓度>200ppm时，燃气设备腐蚀速率加快3倍（参考《燃气轮机腐蚀控制标准GB/T 14090》）；脱硫成本占比：生物脱硫法0.1-0.2元/m，化学吸收法0.3-0.5元/m；

　　(1) The necessity of hydrogen sulfide treatment: When the concentration of H2S is greater than 200ppm, the corrosion rate of gas equipment accelerates by three times (refer to the "Gas Turbine Corrosion Control Standard GB/T 14090"); Cost proportion of desulfurization: 0.1-0.2 yuan/m  for biological desulfurization method, 0.3-0.5 yuan/m  for chemical absorption method;

　　（2）热值波动管理：甲烷浓度每下降5%，锅炉热效率降低2%；典型热值应用场景：发电需>22MJ/m，车用燃气需>31MJ/m（需提纯至CH>90%）。

　　(2) Heat value fluctuation management: For every 5% decrease in methane concentration, the boiler thermal efficiency decreases by 2%; Typical application scenarios for calorific value: power generation requires>22MJ/m Does car gas require>31MJ/m (To be purified to CH>90%).

　　2.3体量测算模型（1）产气量计算公式：Q =k×COD负荷×η×R其中：

　　2.3 Volume Calculation Model (1) Gas Production Calculation Formula: Q=k × COD Load × η × R Where:

　　k：产气系数（0.35-0.45m/kg COD）

　　k: Gas production coefficient (0.35-0.45m/kg COD)

　　η：COD去除率（85-95%）；

　　η: COD removal rate (85-95%);

　　R：运行稳定性系数（0.8-0.95）；

　　R: Operating stability coefficient (0.8-0.95);

　　（2）沼气利用规模经济阈值：提纯项目盈亏平衡点：沼气量≥1500m/d；发电项目经济性拐点：设备利用率>75%（年运行6500小时）。

　　(2) Scale economy threshold for biogas utilization: breakeven point for purification projects: biogas volume ≥ 1500m /d; Economic turning point of power generation projects: equipment utilization rate>75% (annual operation of 6500 hours).

　　三、沼气利用模式分析3.1自备热电厂锅炉掺烧模式掺烧模式是目前最普遍的沼气利用模式，通过污水厂厌氧塔的沼气稳压罐及后面的风机，通过管道送到电厂的分气缸，然后通过燃烧器后进入锅炉的燃烧系统。此模式的关键问题点我认为有两处：

　　3、 Analysis of Biogas Utilization Mode 3.1 Co firing Mode of Self provided Thermal Power Plant Boiler Co firing Mode is currently the most common biogas utilization mode. It is sent through the biogas stabilizing tank of the anaerobic tower in the sewage plant and the fan behind it, through pipelines to the power plant's gas separation cylinder, and then enters the combustion system of the boiler after passing through the burner. I think there are two key issues with this model:

　　一是掺烧沼气虽然投资小、系统简单，但是其在锅炉内部的掺烧对锅炉产生氮氧化物有很大影响，通过我实际的情况来看，一旦投入掺烧系统，脱硝用氨水量马上增加。如果有两个沼气燃烧器运行，就相当于增加了两个燃烧源，大大影响锅炉氮氧化物的产生量。

　　One reason is that although the investment in co firing biogas is small and the system is simple, its co firing inside the boiler has a significant impact on the production of nitrogen oxides. Based on my actual situation, once it is put into the co firing system, the amount of ammonia water used for denitrification immediately increases. If there are two biogas burners running, it is equivalent to adding two combustion sources, greatly affecting the production of nitrogen oxides in the boiler.

　　二是沼气热值高，但是进入炉膛后，实际产生的热效率的大小需要试验确认，也就是说，其产生的热效率并不等于锅炉热效率。沼气在燃煤锅炉内燃烧充分，但是到尾部换热却不能完全完成。我们组织了试验，沼气投入锅炉，稳定燃烧后，在尾部烟气处测量组份，没有可燃元素，那就说明沼气的燃尽率是100%；但同时发现锅炉的排烟温度马上上升，排烟热损失增加，说明在锅炉内沼气燃烧热效率是低于煤炭燃烧热效率的。下面是实际的简单试验的结果：

　　The second reason is that biogas has a high calorific value, but the actual thermal efficiency generated after entering the furnace needs to be confirmed through experiments, which means that the thermal efficiency generated does not equal the boiler thermal efficiency. Biogas is fully burned in coal-fired boilers, but the heat exchange at the tail cannot be fully completed. We organized an experiment and put biogas into the boiler. After stable combustion, the composition was measured at the tail flue gas. If there were no combustible elements, it means that the combustion rate of biogas is 100%; But at the same time, it was found that the exhaust temperature of the boiler immediately increased, and the exhaust heat loss increased, indicating that the thermal efficiency of biogas combustion in the boiler is lower than that of coal combustion. Here are the actual results of a simple experiment:

　　（1）沼气输入热量：Q1=单位小时沼气掺烧量*沼气低位发热量=1400m3*24.4mj/m3=81.58万大卡；

　　(1) Biogas input heat: Q1=unit hour biogas co firing amount * biogas low-level heat generation=1400m3 * 24.4mj/m3=815800 kcal;

　　（2）排烟热损失：Q2=12.8万大卡

　　(2) Smoke exhaust heat loss: Q2=128000 kcal

　　（3）沼气燃烧热效率计算：η=1-Q/Q1=77.6%在我们这台特定锅炉中掺烧，沼气在锅炉实际热效率为77.6%。如果5000大卡煤炭价格为800元，那一立方沼气的经济价值是：24.4/4.1868/5000*800*0.77=0.72元。另外，需要提醒的是：“碳减排盲区”：掺烧模式因无法精确计量沼气替代率，导致CCER（国家核证自愿减排量）开发难度大。

　　(3) Calculation of thermal efficiency of biogas combustion: η=1-Q/Q1=77.6%. In our specific boiler, when co fired, the actual thermal efficiency of biogas in the boiler is 77.6%. If the price of 5000 kcal coal is 800 yuan, the economic value of one cubic meter of biogas is 24.4/4.1868/5000 * 800 * 0.77=0.72 yuan. In addition, it should be noted that there is a "carbon emission reduction blind spot": the co firing mode is difficult to develop due to the inability to accurately measure the biogas substitution rate, making CCER (National Certified Voluntary Emission Reduction) challenging.

　　3.2沼气发电模式考虑到现在企业经济情况不景气，我们开始的项目原则就定位为“乙方投资，乙方运维”的模式，我们把沼气交于对方，对方提供电力和低压工业用蒸汽给我方。

　　3.2 Considering the current economic downturn of the enterprise, our initial project principle was positioned as a "Party B investment, Party B operation and maintenance" model. We handed over the biogas to the other party, who provided us with electricity and low-pressure industrial steam.

　　3.3沼气提纯模式沼气提纯制生物天然气（Bio-CNG）模式，是通过膜分离、PSA（变压吸附）或水洗工艺将沼气甲烷浓度提纯至90%~97%，生产车用燃气或工业燃料。此模式附加值最高（生物天然气售价达3.5~4.5元/m），且可开发碳信用（CCER收益15~30元/吨CO）。

　　3.3 Biogas Purification Mode Biogas purification to produce bio natural gas (Bio CNG) mode is a process of purifying biogas methane concentration to 90%~97% through membrane separation, PSA (pressure swing adsorption) or water washing technology, producing automotive gas or industrial fuel. This mode has the highest added value (the selling price of biogas reaches 3.5-4.5 yuan/m ), and can also develop carbon credits (CCER income of 15-30 yuan/ton CO).

　　本文由 沼气提纯  友情奉献.更多有关的知识请点击  https://www.hneee.net/   真诚的态度.为您提供为全面的服务.更多有关的知识我们将会陆续向大家奉献.敬请期待.

　　This article is a friendly contribution from biogas purification For more related knowledge, please click https://www.hneee.net/ Sincere attitude To provide you with comprehensive services We will gradually contribute more relevant knowledge to everyone Coming soon.