In the process of biogas power generation, biogas generator units are particularly sensitive to the composition, temperature, pressure, and amount of biogas. The generator unit requires that the intake system must maintain a constant and moderate air-fuel ratio to avoid excessive air-fuel ratio that may cause flameout; 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 the temperature, pressure, and composition of biogas can affect the air-fuel ratio. Therefore, before choosing to use biogas for power generation, not properly controlling the biogas quality will lead to the inability of the generator unit to operate normally, resulting in significant economic losses.

1、沼氣質量

1. Biogas quality

利用沼氣發(fā)電，要滿足沼氣發(fā)電機組對沼氣質量的要求，《中大功率沼氣發(fā)電機組》(GBT29488-2003)、《沼氣電站技術規(guī)范》(NY/T1704-2009)對沼氣質量的要求如下。

To generate electricity using biogas, it is first necessary to meet the requirements for biogas quality of biogas generating units. The requirements for biogas quality in the Medium and Large Power biogas generating units (GBT29488-2003) and the Technical Specifications for Biogas Power Plants (NY/T1704-2009) are as follows.

(1) 沼氣低位發(fā)熱值≥14MJ/Nm，相當于沼氣中甲烷體積分數不小于30%。沼氣中甲烷在30s內的體積分數變化率不應超過2%，機組連續(xù)運行期間沼氣中甲烷體積分數變化率不超過5%。

(1) The low calorific value of biogas is ≥ 14MJ/Nm, which is equivalent to the methane volume fraction in biogas not less than 30%. The change rate of methane volume fraction in biogas within 30s shall not exceed 2%, and the change rate of methane volume fraction in biogas during continuous operation of the unit shall not exceed 5%.

(2) 沼氣溫度不高于50℃。

(2) The temperature of biogas shall not be higher than 50 ℃.

(3) 沼氣發(fā)電機組對沼氣成分的具體要求如下表。

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

注：沼氣體積的標準參比條件是101.3kPa，20℃；按照沼氣中所含硫成分全部轉化為硫化氫計算。

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

①H2S對發(fā)電機組的影響

① Impact of H2S on generator sets

沼氣發(fā)電時沼氣中的H2S會對沼氣發(fā)電機組的進氣管道、增壓器、中冷器、火花塞、氣缸套、排氣管和消音器等造成嚴重腐蝕，從而影響機組壽命，所以沼氣在進入發(fā)電機組之前必須進行沼氣預處理，將H2S降到機組允許的范圍內才能保證機組的可靠運行。

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

②水分對發(fā)電機組的影響

② Effect of moisture on generator sets

沼氣發(fā)電過程中，沼氣水分含量過大，會導致發(fā)電機組的進氣壓力損耗過大，嚴重情況下，會引起發(fā)動機功率波動、敲缸、停機等問題，嚴重地影響其使用壽命。其具體表現為：

During biogas power generation, excessive moisture content in biogas can lead to excessive intake pressure loss of the generator set. In severe cases, it can cause engine power fluctuations, cylinder knocking, shutdown, and other issues, seriously affecting its service life. The specific performance is as follows:

(a)發(fā)動機點火困難；

(a) Difficulty in ignition of the engine;

(b)降低燃燒室溫度，降低內燃機效率；

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

(c)水蒸氣等無功氣體的存在，會增壓和增大功耗；

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

(d)水蒸氣與其他酸性物質化合產生的中間產物，會對發(fā)電機組產生腐蝕，縮短使用壽命，降低可靠性。

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

③粉塵對發(fā)電機組的影響

③ Impact of dust on generator sets

粉塵是發(fā)動機明確限制的雜質，它主要影響在于：

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

(a)堵塞管路，流通不暢，加大壓損，增加運行費用；

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

(b)增大機械磨損，降低設備使用壽命。

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

2、沼氣壓力

2. Biogas pressure

沼氣發(fā)電機組在距離機組燃氣支管錢1m處的沼氣壓力不低于3kPa，當供氣壓力低于3kPa時，應配置氣體增壓設備；當供氣壓力超過5kPa時，則需要增加合適的減壓閥。在沼氣發(fā)電機組運行時，發(fā)動機允許的沼氣壓力波動一般要小于0.4kPa/s。

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

3、沼氣用量

3. Biogas consumption

沼氣發(fā)電機組的沼氣用量應根據發(fā)電機組的效率和負荷確定，發(fā)電時沼氣的供氣量應相對穩(wěn)定。在計算沼氣使用量時，應小于沼氣發(fā)電機額定功率耗氣量的1.2倍。供氣系統(tǒng)應設有調節(jié)用氣的設施和氣體計量儀表。沼氣發(fā)電機組連續(xù)運行時，儲氣裝置容量應按照運行機組總額定功率大于3h的用氣量設計。沼氣發(fā)電機組間歇運行時，儲氣裝置容量應按照大于間斷發(fā)電時間的沼氣總量設計。

The amount of biogas used in a biogas generator unit should be determined based on the efficiency and load of the generator unit, and the amount of biogas supplied during power generation should be relatively stable. When calculating the amount of biogas used, it should be less than 1.2 times the rated power consumption of the biogas generator. The gas supply system shall be equipped with facilities for regulating gas consumption and gas metering instruments. During continuous operation of biogas generating units, the capacity of the gas storage device should be designed based on the gas consumption with the total rated power of the operating unit greater than 3h. When the biogas generator unit operates intermittently, the capacity of the gas storage device should be designed based on the total amount of biogas that is greater than the intermittent power generation time.

其中，沼氣發(fā)電機組的用氣調節(jié)系統(tǒng)，一般采用電子調速系統(tǒng)控制碟門開度來實現的，調速系統(tǒng)由轉速傳感器、速度控制器、執(zhí)行器和驅動器組成，構成閉環(huán)的速度調節(jié)與控制系統(tǒng)，實現對混合氣體進氣量的控制。氣體計量儀表一般是采用沼氣流量計，如銳意自控超聲波氣體流量計BF-3000/BF-3000B，用以實時計量沼氣的瞬時流量和累計流量，為計算沼氣使用量提供科學的數據支撐。

Among them, the gas consumption regulation system for biogas generating units 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 rotational speed sensor, a speed controller, an actuator, and a driver, forming a closed-loop speed regulation and control system to achieve control of the intake amount of mixed gas. Gas metering instruments generally use biogas flow meters, such as the Ruiyi Automatic Ultrasonic Gas Flowmeter BF-3000/BF-3000B, to measure the instantaneous and cumulative flow of biogas in real time, providing scientific data support for calculating the amount of biogas used.

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