JPH0346726B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a furnace heating method that efficiently heats a heat treatment furnace for iron, steel, etc. by turning on and off multiple burners, and more precisely equalizes the temperature inside the furnace. .

In the case of a batch-type heating furnace, the amount of combustion is at its maximum at the beginning of heating, and a large amount of combustion gas circulates in the furnace, but after that the amount of combustion gradually decreases, and during uniform heating, the amount of combustion gas is at its maximum during initial heating. It requires only 1/10 to 1/100 of the amount of heat. As a method for reducing the amount of heat, a constant air-fuel ratio combustion system that throttles both air and fuel has already been used, but as the amount of combustion decreases, problems arise in maintaining temperature uniformity. Furthermore, constant air combustion systems have already been used in which the amount of air is fixed at the maximum combustion level and only the amount of combustion is reduced, but this system has poor combustion efficiency during uniform heating. Furthermore, an impulse combustion system in which all burners are turned on (combustion) and off (non-combustion) at the same time is already in use, but the off-time of the burners during uniform heating is long, and during this off-time, the circulation of gas in the furnace is limited. Since this is not carried out, it is difficult to equalize the temperature inside the furnace. Furthermore, a special system that uses a special nozzle and combines a constant air combustion system and a constant air fuel ratio combustion system is known, but the structure is complicated and the combustion efficiency at low combustion times is still insufficient. be.

This invention was made to solve these problems, and embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows a plan view of the furnace. Burners 1, 2..., 7,
8 (however, the left and right burners are arranged in a staggered manner), and these burners perform constant air-fuel ratio combustion at the maximum air injection amount and fuel injection amount during combustion in the on state. In addition, neither air nor fuel is ejected in the off state. Each burner is designed to fire periodically in the order of 1, 2, 3...8, 1, 2,...8, 1 (the ignition order of the burners is set during the test run and remains constant thereafter). ).

Figures 2, 3, and 4 show the operating states of the burner when the required amount of heat is small (occasionally one ignition), medium (4 ignitions), and large (5 ignitions), respectively. Here, x indicates an ignition timing interval that is variable depending on the combustion amount, t indicates one ignition time that is set during test operation and is constant thereafter, and T indicates one cycle that is variable depending on the combustion time.

In this invention, a plurality of burners 1, 2, ..., 8 facing into the furnace are arranged at desired ignition timing intervals x.
, and ignition is periodically repeated in sequence according to a predetermined order, and each ignition time t is kept unchanged, and the desired ignition timing interval x is changed according to the required heat amount, and each burner is Combustion is carried out at a constant air-fuel ratio with the maximum amount of air and fuel ejected.

That is, in this invention, the ignition order and ignition time of the burners are set in advance, and the change in the combustion amount can be controlled in stages according to the number of ignitions of the burners.In other words, as the combustion amount increases, the ignition timing interval x The cycle T becomes smaller, in other words, the number of burners ignited (the number of burners ignited at the same time) increases, that is, the ignition timing interval x changes as the combustion amount changes, and at low combustion times. It also has excellent combustion efficiency.

Note that it is convenient to calculate the required amount of heat based on the temperature difference between a predetermined furnace atmosphere setting temperature and a temperature measured at a furnace control point.

[Brief explanation of drawings]

The drawings are for explaining this invention.
The figures are perspective plan schematic diagrams of the furnace, Figures 2, 3, and 4.
The figure is a graph showing the operating state of the burner when the required amount of heat is small, medium, and large, respectively. 1-8... Burner, 9... Furnace, 10, 11...
...Right and left side walls of the furnace, t...Ignition time, T...Period, x...Ignition timing interval.

Claims (1)

[Claims] 1. A plurality of burners 1, 2,... facing into the furnace.
. The on/off method for multiple burners is characterized in that the amount of heat is varied according to the required amount of heat, and each burner performs constant air-fuel ratio combustion at the maximum air and fuel injection amounts.
Furnace heating method by off-combustion. 2. The required amount of heat is calculated based on the temperature difference between a predetermined furnace atmosphere setting temperature and a temperature measured at a furnace control point. Furnace heating method.