Master's work:

Reliable and effective work of the heat supply centralized system of substantially depends on heating engineering and operating descriptions of the thermal equipment.

In most cases any burners while in service work in the conditions which are distinct from settlement. First of all productivity of a torch due to manual or automatic influence on it, as a rule, varies.

Special conditions in work of torches are created in the case when such basic characteristics of gas fuel as heat of its combustion and relative density vary.

Process of burning of gas consists of consistently proceeding stages:

a) Formation of a homogeneous air-gas mixture (fuel and oxidizer);

b) Heating of a mixture up to the temperature of ignition;

c) Chemical reaction - actually reaction of combustion.

The stage of mixing renders essential influence on burning and can be carried out or as a preliminary (preparatory) stage, or to occur in parallel to other processes.

Stages of mixing in gas gas-ring devices are the most important as stabilization of a flame, depth of regulation, ecological parameters and reliability of operation of gas-burning devices are appreciably defined by maintenance of stability of conditions of formation of an air-gas mixture in various modes of burning.

Stabilizing of process of burning in gas-burning devices with complete preliminary mixing is carried out in the ranges of speeds of output of air-gas of mixture from openings of gas-ring head, eliminating "breakthrough" and "tearing" away of front of flame. Graphicaly the area of stable operation of gas-burning devices with complete preliminary mixing on natural gas is illustrated (fig. 1) an area between the curves of " breakthrough " and "tearing" away of flame for the values alpha>1.

Speeds of "tearing" away and " breakthrough " of flame depends on correlation of speed of output of aerofuel mixture and speed of distribution of flame (that from composition of gas and coefficient of excess of primary air alpha ') and from the terms of flameholding at a root every conflagrant of gas-ring device. As follows from figure 1, a zone of steady burning of a torch with full preliminary mixture (and alpha '>1) is rather narrow. So, at alpha =1,2 (for the torch resulted as an example on fig. 1) a ratio of speeds on an output: wот/ w пр = 1,45/0,73=2, That is the range of steady burning, corresponds to depth of regulation of capacity of a torch from 50 up to 100 %

To expand a range of steady work of a torch it is possible enriching a primary mix (reducing factor of surplus of primary air and alpha ' (figure 1)), that reduces probability "breakthrough" a flame down to its exception on conditions of ignition (and alpha '<0,65 for natural gas). At the same time speed tearing a flame due to the best diffusion of fuel from a "rich" mix in the basis of torches of a torch where together with secondary air the stabilizing center of burning is formed increases also. Therefore torches with incomplete preliminary mixture possess greater depth of regulation and rather the best stabilization of a flame.