一、沼气发电机组特性

1、 Characteristics of biogas generator sets

甲烷之所以能成为燃料是因为含有50%以上的甲烷。 一般甲烷含有60~70%的甲烷。 每立方米甲烷的低热量约为5000~6000千卡，具有高热值。 由于甲烷中含有二氧化碳，火焰传播速度降低，内燃机内有良好的抗爆性能，甲烷辛烷值在105~115之间，甲烷高达135。 由于耐暴性良好，发动机可以选择较高的压缩比，因此只要是相同工作容积的内燃机，在使用沼气时就能够得到比原机更高的输出功率。 例如，农村大量拥有的沼气发电机组，在使用沼气或双燃料工作时，可以获得与原机相当的电力。 这给辅助器具带来便利，例如，以S195型马力柴油机为例，它原配有两种以上的水泵，以及拖拉机、打米、饲料粉碎、发电等工具，其辅助转速和功率已经确定了很多年。 如果要变更的话，为沼气发电机组新开发这么大的新产品，工作效率会提高，很难普及吧。

The reason why methane can become a fuel is because it contains more than 50% methane. Generally, methane contains 60-70% methane. The low calorific value of methane per cubic meter is about 5000-6000 kcal, with a high calorific value. Due to the presence of carbon dioxide in methane, the flame propagation speed is reduced, and the internal combustion engine has good anti knock performance. The octane number of methane is between 105 and 115, and methane can reach up to 135. Due to its good durability, the engine can choose a higher compression ratio, so as long as it is an internal combustion engine with the same working volume, it can achieve higher output power than the original engine when using biogas. For example, a large number of biogas generators in rural areas can obtain electricity equivalent to the original ones when using biogas or dual fuel for operation. This brings convenience to auxiliary equipment. For example, taking the S195 horsepower diesel engine as an example, it was originally equipped with two or more types of water pumps, as well as tools such as tractors, rice milling, feed crushing, and power generation. Its auxiliary speed and power have been determined for many years. If we want to make changes, developing such a large new product for biogas generator sets will improve work efficiency, and it is difficult to popularize it, right.

二、柴油机甲烷改造方法

2、 Methods for methane transformation in diesel engines

柴油发动机和点火型发动机(汽油发动机)是比较经济的内燃机。 这两种发动机在用甲烷作燃料之前须进行改造，为燃烧室提供适当的混合气。 即在气化器前增加甲烷-空气混合器。

Diesel engines and ignition engines (gasoline engines) are relatively economical internal combustion engines. These two engines need to be modified before using methane as fuel to provide an appropriate mixture for the combustion chamber. Add a methane air mixer in front of the gasifier.

沼气发动机一般分为压缩燃烧式和点火式两种。

Biogas engines are generally divided into two types: compression combustion and ignition.

压缩式发动机采用柴油-沼气双燃料，少量柴油压缩燃烧点燃沼气进行燃烧功。 该发动机的特点是可以调节柴油/甲烷比，即使甲烷不足或燃气停止，发动机也能正常工作。 缺点是系统复杂，大型沼气发电工程往往不采用这种发动机。 其特点是多采用先导式沼气发动机，又称全燃式沼气发动机，结构简单，操作方便，无需辅助燃料，适合大中型沼气工程作业。 将柴油发动机改造为先导沼气发动机，除气化器前增加沼气―空气混合器外，还需要增加电点火系统，同时增加火花塞。

The compression engine uses diesel biogas dual fuel, with a small amount of diesel compressed combustion igniting biogas for combustion work. The characteristic of this engine is that it can adjust the diesel/methane ratio, and even if there is insufficient methane or gas stops, the engine can still operate normally. The disadvantage is that the system is complex, and large-scale biogas power generation projects often do not use this type of engine. Its characteristic is the use of pilot type biogas engines, also known as full combustion biogas engines. It has a simple structure, convenient operation, and does not require auxiliary fuel, making it suitable for large and medium-sized biogas engineering operations. To transform a diesel engine into a pilot biogas engine, in addition to adding a biogas air mixer in front of the gasifier, it is also necessary to add an electric ignition system and spark plugs.

三、沼气发电机组操作方法及注意事项

3、 Operating methods and precautions for biogas generator sets

使用方法：

Usage:

1、启动：关闭沼气阀，根据柴油机启动方法，柴油启动操作方法与未改造前相同。

1. Start: Close the biogas valve, and according to the diesel engine start method, the diesel start operation method is the same as before the modification.

2、启动后操作：启动后加载，柴油发动机油门放在合适位置(一般低于中间位置)，待发动机正常运行后，缓慢打开沼气阀门，注入甲烷。 供给甲烷后，在调速器的作用下供油量自动减少，发动机转速稳定。 如果沼气供给量过多，发动机会瞬间中断供油，发出断断续续的工作声。 遇到这种情况，须随时关闭一点，直到沼气阀正常工作。 运行中，调整转速的方法与改造前用柴油工作时一样，通过改变油门把手的位置来进行。 随着双燃料发动机转速和负荷大小的变化，为了确保双燃料发动机的正常运转和较高的油耗效果，须相应地增大或减小沼气阀。沼气发电机组冷却水温低，在小负荷下运行时，得不到低油耗效果。

2. Post start operation: After starting, load the diesel engine and place the throttle in the appropriate position (usually lower than the middle position). After the engine runs normally, slowly open the biogas valve and inject methane. After supplying methane, the fuel supply automatically decreases under the action of the governor, and the engine speed stabilizes. If the biogas supply is too high, the engine will instantly interrupt fuel supply and make intermittent working sounds. In this situation, it is necessary to close it at any time until the biogas valve is working properly. During the operation, the method of adjusting the speed is the same as that of working with diesel before the transformation, by changing the position of the throttle handle. As the speed and load of the dual fuel engine change, in order to ensure the normal operation and high fuel consumption of the dual fuel engine, it is necessary to correspondingly increase or decrease the biogas valve. The cooling water temperature of the biogas generator set is low, and it cannot achieve low fuel consumption when operating at low loads.