1、 Quality requirements for generator sets

在沼氣發(fā)電過程中，沼氣發(fā)電機組對沼氣的成分、溫度、壓力、用量特別敏感，發(fā)電機組要求進(jìn)氣系統(tǒng)必須保持空燃比的恒定和適度，避免空燃比過大，引起熄火；也要避免空燃比過小，引起溫度高及爆震。空燃比是影響沼氣發(fā)電機燃燒性能的重要因素之一，而沼氣溫度、壓力、成分的變化都會影響空燃比，因此，在選擇進(jìn)行沼氣發(fā)電前，不對沼氣氣質(zhì)進(jìn)行合理的把控，將導(dǎo)致發(fā)電機組無法正常運行，造成較大的經(jīng)濟損失。

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、沼氣質(zhì)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(zhì)量的要求，《中大功率沼氣發(fā)電機組》(GBT29488-2003)、《沼氣電站技術(shù)規(guī)范》(NY/T1704-2009)對沼氣質(zhì)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) 沼氣低位發(fā)熱值≥14MJ/Nm，相當(dāng)于沼氣中甲烷體積分?jǐn)?shù)不小于30%。沼氣中甲烷在30s內(nèi)的體積分?jǐn)?shù)變化率不應(yīng)超過2%，機組連續(xù)運行期間沼氣中甲烷體積分?jǐn)?shù)變化率不超過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) 沼氣溫度不高于50℃。

(2) The temperature of biogas shall not exceed 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 composition of biogas generator units are shown in the table below.

注：沼氣體積的標(biāo)準(zhǔn)參比條件是101.3kPa，20℃；按照沼氣中所含硫成分全部轉(zhuǎn)化為硫化氫計算。

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對發(fā)電機組的影響

① The 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(jìn)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(yán)重腐蝕，從而影響機組壽命，所以沼氣在進(jìn)入發(fā)電機組之前必須進(jìn)行沼氣預(yù)處理，將H2S降到機組允許的范圍內(nèi)才能保證機組的可靠運行。

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水分對發(fā)電機組的影響

② The impact of moisture on generator sets

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

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)發(fā)動機點火困難；

(a) Difficulty in engine ignition;

(b)降低燃燒室溫度，降低內(nèi)燃機效率；

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

(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 increase pressure and power consumption;

(d)水蒸氣與其他酸性物質(zhì)化合產(chǎn)生的中間產(chǎn)物，會對發(fā)電機組產(chǎn)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 corrode the generator set, shorten its service life, and reduce its reliability.

③粉塵對發(fā)電機組的影響

③ The impact of dust on generator sets

粉塵是發(fā)動機明確限制的雜質(zhì)，它主要影響在于：

Dust is a clearly restricted impurity in engines, 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, poor circulation, increased pressure loss, and increased operating costs;

(b)增大機械磨損，降低設(shè)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?xì)庵Ч苠X1m處的沼氣壓力不低于3kPa，當(dāng)供氣壓力低于3kPa時，應(yīng)配置氣體增壓設(shè)備；當(dāng)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 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、沼氣用量

3. Biogas consumption

沼氣發(fā)電機組的沼氣用量應(yīng)根據(jù)發(fā)電機組的效率和負(fù)荷確定，發(fā)電時沼氣的供氣量應(yīng)相對穩(wěn)定。在計算沼氣使用量時，應(yīng)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(yīng)設(shè)有調(diào)節(jié)用氣的設(shè)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(yīng)按照運行機組總額定功率大于3h的用氣量設(shè)計。沼氣發(fā)電機組間歇運行時，儲氣裝置容量應(yīng)按照大于間斷發(fā)電時間的沼氣總量設(shè)計。

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，沼氣發(fā)電機組的用氣調(diào)節(jié)系統(tǒng)，一般采用電子調(diào)速系統(tǒng)控制碟門開度來實現(xiàn)的，調(diào)速系統(tǒng)由轉(zhuǎn)速傳感器、速度控制器、執(zhí)行器和驅(qū)動器組成，構(gòu)成閉環(huán)的速度調(diào)節(jié)與控制系統(tǒng)，實現(xiàn)對混合氣體進(jìn)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(xué)的數(shù)據(jù)支撐。

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.

超聲波氣體流量計BF-3000采用行業(yè)的超聲波氣體傳感技術(shù)，可用于大中小型沼氣工程站內(nèi)流量計量，并采集現(xiàn)場壓力和溫度。其獨有的甲烷濃度測量功能，可為沼氣工程站內(nèi)流量計量、驗收、監(jiān)督提供優(yōu)化的測量方案。

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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