1、 Quality requirements for generator sets

在沼气发电过程中，沼气发电机组对沼气的成分、温度、压力、用量特别敏感，发电机组要求进气系统必须保持空燃比的恒定和适度，避免空燃比过大，引起熄火；也要避免空燃比过小，引起温度高及爆震。空燃比是影响沼气发电机燃烧性能的重要因素之一，而沼气温度、压力、成分的变化都会影响空燃比，因此，在选择进行沼气发电前，不对沼气气质进行合理的把控，将导致发电机组无法正常运行，造成较大的经济损失。

In the process of biogas power generation, the biogas generator set is particularly sensitive to the composition, temperature, pressure, and dosage of biogas. The generator set requires the intake system to maintain a constant and moderate air fuel ratio to avoid excessive air fuel ratio, which may cause stalling; It is also necessary to avoid excessively low air fuel ratio, which can cause high temperature and detonation. The air fuel ratio is one of the important factors that affect the combustion performance of biogas generators, and changes in biogas temperature, pressure, and composition can all affect the air fuel ratio. Therefore, before choosing biogas power generation, not controlling the biogas quality reasonably will lead to the inability of the generator set to operate normally and cause significant economic losses.

1、沼气质量

1. Biogas quality

利用沼气发电，要满足沼气发电机组对沼气质量的要求，《中大功率沼气发电机组》(GBT29488-2003)、《沼气电站技术规范》(NY/T1704-2009)对沼气质量的要求如下。

To use biogas for power generation, the first step is to meet the requirements of biogas power generation units for biogas quality. The requirements for biogas quality in the "Medium and High Power biogas power generation units" (GBT29488-2003) and "Technical Specifications for biogas power plants" (NY/T1704-2009) are as follows.

(1) 沼气低位发热值≥14MJ/Nm，相当于沼气中甲烷体积分数不小于30%。沼气中甲烷在30s内的体积分数变化率不应超过2%，机组连续运行期间沼气中甲烷体积分数变化率不超过5%。

(1) The low calorific value of biogas is ≥ 14MJ/Nm, which is equivalent to a methane volume fraction of no less than 30% in biogas. The change rate of methane volume fraction in biogas within 30 seconds should not exceed 2%, and the change rate of methane volume fraction in biogas during continuous operation of the unit should not exceed 5%.

(2) 沼气温度不高于50℃。

(2) The temperature of biogas shall not exceed 50 ℃.

(3) 沼气发电机组对沼气成分的具体要求如下表。

(3) The specific requirements for biogas composition of biogas generator units are shown in the table below.

注：沼气体积的标准参比条件是101.3kPa，20℃；按照沼气中所含硫成分全部转化为硫化氢计算。

Note: The standard reference conditions for biogas volume are 101.3kPa, 20 ℃; Calculate based on the conversion of all sulfur-containing components in biogas into hydrogen sulfide.

①H2S对发电机组的影响

① The impact of H2S on generator sets

沼气发电时沼气中的H2S会对沼气发电机组的进气管道、增压器、中冷器、火花塞、气缸套、排气管和消音器等造成严重腐蚀，从而影响机组寿命，所以沼气在进入发电机组之前必须进行沼气预处理，将H2S降到机组允许的范围内才能保证机组的可靠运行。

During biogas power generation, the H2S in the biogas can cause serious corrosion to the intake pipes, superchargers, intercoolers, spark plugs, cylinder liners, exhaust pipes, and silencers of the biogas generator set, thereby affecting the lifespan of the unit. Therefore, before biogas enters the generator set, biogas pretreatment must be carried out to reduce the H2S to the allowable range of the unit in order to ensure the reliable operation of the unit.

②水分对发电机组的影响

② The impact of moisture on generator sets

沼气发电过程中，沼气水分含量过大，会导致发电机组的进气压力损耗过大，严重情况下，会引起发动机功率波动、敲缸、停机等问题，严重地影响其使用寿命。其具体表现为：

In the process of biogas power generation, excessive moisture content in biogas can lead to excessive loss of intake pressure of the generator set. In severe cases, it can cause problems such as engine power fluctuations, cylinder knocking, and shutdown, seriously affecting its service life. Its specific manifestation is:

(a)发动机点火困难；

(a) Difficulty in engine ignition;

(b)降低燃烧室温度，降低内燃机效率；

(b) Reduce the temperature of the combustion chamber and reduce the efficiency of the internal combustion engine;

(c)水蒸气等无功气体的存在，会增压和增大功耗；

(c) The presence of reactive gases such as water vapor can increase pressure and power consumption;

(d)水蒸气与其他酸性物质化合产生的中间产物，会对发电机组产生腐蚀，缩短使用寿命，降低可靠性。

(d) The intermediate products produced by the combination of water vapor and other acidic substances can corrode the generator set, shorten its service life, and reduce its reliability.

③粉尘对发电机组的影响

③ The impact of dust on generator sets

粉尘是发动机明确限制的杂质，它主要影响在于：

Dust is a clearly restricted impurity in engines, and its main impact is:

(a)堵塞管路，流通不畅，加大压损，增加运行费用；

(a) Blocking the pipeline, poor circulation, increased pressure loss, and increased operating costs;

(b)增大机械磨损，降低设备使用寿命。

(b) Increase mechanical wear and reduce equipment service life.

2、沼气压力

2. Biogas pressure

沼气发电机组在距离机组燃气支管钱1m处的沼气压力不低于3kPa，当供气压力低于3kPa时，应配置气体增压设备；当供气压力超过5kPa时，则需要增加合适的减压阀。在沼气发电机组运行时，发动机允许的沼气压力波动一般要小于0.4kPa/s。

The biogas pressure of the biogas generator set at a distance of 1 meter from the gas branch pipe of the unit shall not be less than 3 kPa. When the gas supply pressure is less than 3 kPa, gas boosting equipment shall be equipped; When the gas supply pressure exceeds 5kPa, it is necessary to add a suitable pressure reducing valve. When the biogas generator set is running, the allowable biogas pressure fluctuation of the engine is generally less than 0.4kPa/s.

3、沼气用量

3. Biogas consumption

沼气发电机组的沼气用量应根据发电机组的效率和负荷确定，发电时沼气的供气量应相对稳定。在计算沼气使用量时，应小于沼气发电机额定功率耗气量的1.2倍。供气系统应设有调节用气的设施和气体计量仪表。沼气发电机组连续运行时，储气装置容量应按照运行机组总额定功率大于3h的用气量设计。沼气发电机组间歇运行时，储气装置容量应按照大于间断发电时间的沼气总量设计。

The amount of biogas used in a biogas generator set should be determined based on the efficiency and load of the generator set, and the supply of biogas during power generation should be relatively stable. When calculating the usage of biogas, it should be less than 1.2 times the rated power consumption of the biogas generator. The gas supply system should be equipped with facilities for regulating gas consumption and gas measuring instruments. When the biogas generator unit operates continuously, the capacity of the gas storage device should be designed based on the total rated power of the operating unit exceeding 3 hours of gas consumption. When the biogas generator unit operates intermittently, the capacity of the gas storage device should be designed based on the total amount of biogas greater than the intermittent power generation time.

其中，沼气发电机组的用气调节系统，一般采用电子调速系统控制碟门开度来实现的，调速系统由转速传感器、速度控制器、执行器和驱动器组成，构成闭环的速度调节与控制系统，实现对混合气体进气量的控制。气体计量仪表一般是采用沼气流量计，如锐意自控超声波气体流量计BF-3000/BF-3000B，用以实时计量沼气的瞬时流量和累计流量，为计算沼气使用量提供科学的数据支撑。

Among them, the gas regulation system of the biogas generator unit is generally achieved by using an electronic speed regulation system to control the opening of the disc door. The speed regulation system consists of a speed sensor, speed controller, actuator, and driver, forming a closed-loop speed regulation and control system to achieve control of the mixed gas intake volume. Gas measuring instruments generally use biogas flow meters, such as the Ruiyi self-control ultrasonic gas flow meter BF-3000/BF-3000B, to measure the instantaneous and cumulative flow of biogas in real-time, providing scientific data support for calculating biogas usage.

超声波气体流量计BF-3000采用行业的超声波气体传感技术，可用于大中小型沼气工程站内流量计量，并采集现场压力和温度。其独有的甲烷浓度测量功能，可为沼气工程站内流量计量、验收、监督提供优化的测量方案。

The ultrasonic gas flow meter BF-3000 adopts industry-leading ultrasonic gas sensing technology and can be used for flow measurement in large, medium, and small biogas engineering stations, as well as collecting on-site pressure and temperature. Its unique methane concentration measurement function can provide optimized measurement solutions for flow measurement, acceptance, and supervision within biogas engineering stations.

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