The issue of gas interchange is related to the development of the gas industry. In the early days of the development of urban gas industry, coal gas was mostly used as the gas source. The single gas component of the gas production method changed very little, and there was no gas interchange problem. Gas companies can control gas quality with just one parameter. Initially, gas was used for lighting, and only the parameter luminosity was used to control gas quality. Later, when gas was used for heating, the calorific value parameter began to be used to control gas quality. As the scale of gas supply expands, the types of gas sources gradually increase, and the range of changes in gas components increases, so that the calorific value parameter can no longer control gas quality.
In 1926, the Italian engineer Roberto Roberto proposed the Roberto Roberto index, which reflects two factors: calorific value and relative density, and used it as a parameter to control gas quality. With the further increase in the types of gas sources, the gas components have become more complex, and the Wobei index alone is still not enough to control the gas quality. Therefore, various countries have systematically carried out research on gas interchangeability, and determined interchangeability based on the gas combustion characteristics. Determination index. There are many methods to determine interchangeability in the world, but the American Gas Association (A.GA) determination method and the Delbourg method of GDF are the most influential. What the two have in common is that they are based on a large amount of experimental data, conduct theoretical analysis and induction, and arrive at a universally significant interchangeability judgment index and method.
The most basic way to determine whether the two gases are interchangeable is through experimental means. Gas interchangeability tests are generally conducted on specially designed control burners. Although the types of control burners used in various countries are different, they are all atmospheric burners that produce Bunsen flames. Countries have different requirements for exchange conditions, some have stricter restrictions and some have looser restrictions. The subjects and depth and breadth of experiments carried out in various countries are also different. Some are aimed at gas with high calorific value, some only consider the tempering factor, and some only consider the flame separation factor. Therefore every empirical formula has its limitations
The Wobbe number is a parameter representing the characteristics of gas. It is assumed that the calorific value and density of two kinds of gases are different, but as long as their Wobbe number is equal, the same heat load can be obtained under the same gas pressure and on the same burning appliance. If the Wobbe number of one of the gases is higher than that of the other, If one is large, the heat load it can achieve is also large. Therefore, the Wobbe number is also called the heat load index.