JPH0144766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heating batch furnaces used for heat treatment of iron, steel, etc., which efficiently heats batch furnaces and reduces harmful components in exhaust gas.

In the case of batch-type heating furnaces, 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 soaking heating, the amount of combustion is 1/1 of the initial heating. It requires only 10 to 1/100 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, air circulation within the furnace chamber deteriorates, causing problems in maintaining temperature uniformity. Also, constant air combustion systems are already in use, in which the amount of air is fixed at the maximum combustion level and only the amount of fuel is reduced. Although air circulation inside the furnace chamber is good, combustion efficiency is poor. Furthermore, impulse combustion systems that turn on and off all burners at the same time are already in use, but the burner off time during uniform heating is long, and during this off time there is no circulation of gas in the furnace. Therefore, 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 also known.
The structure is complicated and there is a feeling that there is still a way to improve combustion efficiency at low combustion times. This invention was made to solve these problems.

A first embodiment of the present invention will be described based on FIGS. 1 to 8.

9 is a batch type heating furnace, 10 is a furnace chamber of the heating furnace 9,
1, 2, and 3 are the furnace chambers 10 in FIGS. 1 and 2.
High-speed jet burner installed on the right side wall of 4.
5 and 6 are the furnace chamber 1 in Figures 1 and 2.
A high-speed jet burner is installed on the left side wall of the heating furnace 9, and the left and right burners are sequentially arranged at different intervals along the furnace length direction of the heating furnace 9. In addition, these burners can be operated as on-keeping burners, in which combustion is always on after ignition, or on/off operation burners, in which the on-state and off-state are alternately performed after ignition. During combustion in the on state, combustion is performed at a constant air-fuel ratio with the maximum air injection amount and maximum combustion ejection amount, and in the off state, neither air nor fuel is ejected. It's getting old.
In this first embodiment, the following five cases are set in order to control the combustion amount in the furnace chamber 10 in stages by changing the number of ignited burners. That is, in the first control stage, the combustion amount is the smallest, and only one burner is fired at a time, but multiple burners are sequentially switched and ignited. To explain this using Fig. 3, the horizontal axis represents time, and the vertical axis represents the sign of the burner being burned.In the first unit of time T, burner 1 is ignited and burned, and in the next unit of time, burner 1 is ignited and burned. 5
Switch to burn it. In this way, one burner is burned one by one, and one cycle L takes 6 units of time.
This process is repeated.

In this first stage of control, each burner all operates as an on-off burner during its assigned time, as shown by the dotted line in the graph of FIG.

For on-off operation burners, if you shorten the on time and lengthen the off time, the amount of heat generated during the shared time will be lower even if the size of the burner frame is the same. If the time is shortened, the amount of heat generated during the shared time will increase. In this first control stage, heat is generated from 0 to 1/6 of the maximum heat generation amount.

Next, in the second control stage, two burners are fired at once. To explain this with reference to FIG. 4, during the first unit of time T, burners 1 and 5 are ignited and burned. In this case, one burner 1 is a keep-on burner, shown in solid lines, and the other burner 5 is an on-off operating burner, shown in dotted lines. In the next unit of time, burner 3 and burner 5 are ignited and burned, and in this way, the burners are sequentially switched two by two, and combustion is performed for six unit times as one cycle L. In this case as well, the on-off operating burner adjusts the amount of heat generated by changing the on/off time ratio, and in this second control stage, heat is generated between 1/6 and 2/6 of the maximum amount of heat.

In the third control stage, as shown in Fig. 5, one period L is twice the time of the unit T, and each unit is controlled by two on-keeping burners and one on/off operation burner to control the amount of heat generated. Make adjustments.

In the fourth control stage, as shown in Fig. 6, one period L is twice the time of the unit T, and each unit is controlled by three on-keeping burners and two (however, only one burner is on). The amount of heat generated is adjusted by the on/off operation burners (both burners are not on at the same time). In this fourth control stage, 3/6 to 4/6 of the maximum heat generation amount is generated.

In the fifth control stage, as shown in Fig. 7, the time of one unit T becomes one period L, and the heat generation amount of each unit is adjusted by four on-keeping burners and two on-off operating burners. . In this fifth control stage, heat is generated from 4/6 to 6/6 of the maximum heat amount (this control stage is divided into two stages, 4/6 to 5/6 and 5/6 to 6/6). ).

FIG. 8 is a graph showing the relationship between the control stage and the combustion amount, with the horizontal axis representing the control stage and the vertical axis representing the combustion amount. 1, 2, 3, 4, and 5 each indicate the number of control stages, A represents the combustion portion by the on-off operating burner, and B represents the combustion portion by the on-maintaining burner.

A second embodiment of the present invention will be explained based on FIGS. 9 to 17.

In this embodiment, the left ceiling burner 17, the right side wall burner 11, the left side wall burner 13, the right ceiling burner 15, the left ceiling burner 18, the right side wall burner 12, and the left side wall burner 1 of the furnace chamber 10.
4. The right ceiling burners 16 are arranged to be sequentially shifted along the longitudinal direction of the furnace chamber 10. Each of the side wall burners 11, 12, 13, and 14 is set to output half the capacity of each of the ceiling burners 15, 16, 17, and 18.

In addition, each side wall burner 11, 12, 13, 14
can be performed in either the on-maintenance state or the on-off operating state. But ceiling burners 15, 16, 1
7 and 18 can be performed only in the ON maintenance state, and cannot be performed in the ON/OFF operation state.

Figure 11 is a graph showing the state of the first control stage, where 4 times the unit T is one period L, and each unit has four side wall burners that adjust the heat output one by one as an on/off burner. . In this first control stage, heat is generated between 0 and 1/12 of the maximum heat amount.

Figure 12 is a graph showing the state of the second control stage, where 6 times the unit T is one period L, and each unit has four sidewall burners, one on-keeping sidewall burner, and one on/off operation sidewall. The amount of heat generated is adjusted by the burner. This second control stage produces 1/1 of the maximum heat generation amount.
12 to 2/12 fever.

Figure 13 is a graph showing the state of the third control stage, where twice the unit T is one period L, and four side wall burners maintain each unit with two side wall burners on and two on/off operations. The amount of heat generated is adjusted by the side wall burner. In this third control stage, heat is generated from 2/12 to 4/12 of the maximum heat amount.

Figure 14 is a graph showing the state of the fourth control stage, where twice the unit T is one cycle L, and the amount of heat generated is adjusted by two on-off operating side wall burners and two on-maintaining ceiling burners. I do. In this fourth control stage, heat is generated from 4/12 to 6/12 of the maximum heat amount.

FIG. 15 is a graph showing the state of the fifth control stage, where twice the unit T is one period L, and each unit is divided into two on-keeping side wall burners, two on/off operation side wall burners, and two on-off operation side wall burners. The amount of heat generated is adjusted by keeping the ceiling burner on. In this fifth control stage, heat is generated from 6/12 to 8/12 of the maximum heat amount.

FIG. 16 is a graph showing the state of the sixth control stage.
The amount of heat generated is regulated by a book on/off side wall burner and four on/off ceiling burners.
In this sixth control stage, heat of 8/12 to 12/12 of the maximum heat amount is generated.

FIG. 17 is a diagram corresponding to FIG. 8 of the first embodiment, and A
The part B represents the side wall burner that operates on and off, the part B represents the side wall burner that remains on, and the part C represents the combustion part that uses the ceiling burner that maintains on.

As described above, the heating method of the batch furnace according to the present invention has two states: a continuous ON state in which only combustion occurs during the unit time T after ignition, and a combustion state and a non-combustion state at short intervals during the unit time T after ignition. An even number of high-speed jet burners are installed in the furnace chamber along the length of the furnace. The left and right side walls of the furnace chamber are opened alternately in a staggered manner, and in the same control stage, the left and right halves of the furnace chamber have the same number of burners kept on and the same number of burners in on/off operation. The burners are arranged alternately every unit time T, and the burners in the ON state and the burners in the ON/OFF state are alternately arranged from the left half and the right half of the furnace chamber along the length direction of the furnace chamber. At the same time, the same combustion order is repeated with the period L being an arbitrary multiple of the unit time, and as the number of combustion control stages increases, the number of burners kept on increases, and the first control stage with the minimum combustion amount is Except for this, the number of burners kept on within a unit time T is greater than the number of burners kept on/off.

Now, combustion is performed at the air-fuel ratio with the highest combustion efficiency over the entire combustion range, and since the burner used is a high-speed jet burner, a large amount of wake gas is stirred inside the furnace and the temperature is uniform throughout the heating and soaking periods. It is possible to ensure that

In addition, in the same control stage, the left half and right half of the furnace chamber have the same number of burners kept on and burners in the on/off operation state, which are alternately repositioned every unit time T. The amount of heating in the left and right halves of the chamber becomes equal, preventing uneven heating from occurring.

Furthermore, since the period L is an arbitrary multiple of the unit time T, and the same combustion order is repeated, design and control are easy. It is possible to heat objects with high thermal efficiency.

Furthermore, since the number of burners kept in the ON state is greater than the number of burners in the ON/OFF operation state, except for the first control stage with the minimum combustion amount, it is possible to extremely reduce the occurrence of temperature irregularities in the furnace interior. Moreover, the first
In all control stages except the control stage, the burners operating from the left side of the furnace chamber and the burners operating from the right side are alternately arranged along the furnace length direction, so heating can be performed with less unevenness. I can do it.

Therefore, there is no localized overheating, and energy-saving and low-pollution (particularly low NOx generation) operation is possible over the entire range.

[Brief explanation of drawings]

1 to 8 are for explaining a first embodiment of the batch furnace heating method according to the present invention,
Fig. 1 is a schematic front view of the batch heating furnace, Fig. 2 is a plan view of the same as above, Fig. 3 is a graph showing the operating state of the first control stage, and Fig. 4 is a graph showing the operating state of the second control stage. , Fig. 5 is a graph showing the operating state of the third control stage, Fig. 6 is a graph showing the operating state of the fourth control stage, Fig. 7 is a graph showing the operating state of the fifth control stage, and Fig. 8 is a graph showing the operating state of the fifth control stage. It is a graph showing the relationship between control stage and combustion amount. 9 to 17 are for explaining a second embodiment of the furnace heating method according to the present invention, and FIG. 9 is a schematic front view of a batch-type heating furnace;
Figure 0 is a plan view of the same as above, Figure 11 is a graph showing the operating state of the first control stage, Figure 12 is a graph showing the operating state of the second control stage, and Figure 13 is a graph showing the operating state of the third control stage. Graph, FIG. 14 is a graph showing the operating state of the fourth control stage, FIG. 15 is a graph showing the operating state of the fifth control stage, FIG. 16 is a graph showing the operating state of the sixth control stage, and FIG. 17 is a graph showing the operating state of the sixth control stage. is a graph showing the relationship between the control stage and the combustion amount. 1... Burner, 2... Burner, 3... Burner, 4... Burner, 5... Burner, 6...
Burner, 9... Batch type heating furnace, 10... Furnace chamber, 11... Burner, 12... Burner, 13
... Burner, 14 ... Burner, 15 ... Burner, 16 ... Burner, 17 ... Burner, 1
8...Burner.

Claims (1)

[Claims] 1. On-maintenance state in which only combustion occurs during the unit time (T) after ignition, and the unit time (T) after ignition
During ignition, an even number of high-speed engines are operated at a constant air-fuel ratio with good combustion efficiency, and at full load. The exhaust burners are opened alternately along the furnace length direction on the left and right side walls of the furnace chamber, and in the same control stage, the same number of burners are kept turned on in the left and right halves of the furnace chamber. The burners in the ON state and the same number of burners in the ON/OFF operating state are arranged alternately every unit time (T), and the burners in the ON state and the burners in the ON/OFF operating state are arranged in the furnace length direction of the furnace chamber. , the combustion takes place alternately from the left half and the right half of the furnace chamber, and the same combustion order is repeated with the period (L) being an arbitrary multiple of the unit time (T), and the number of combustion control stages increases. At the same time, the number of burners in the ON state increases, and the number of burners in the ON state within a unit time (T) is greater than the number of burners in the ON/OFF operating state, except for the first control stage with the minimum combustion amount. Batch furnace heating method.