JPS62248916A - Method of controlling temperature in furnace - Google Patents

Abstract

PURPOSE:To make it possible to improve heating performance in the initial stage of temperature rising and conduct temperature regulation in a furnace exactly and easily by maintaining in the initial stage of temprature rising the amount of fuel supply to a burner at substantially a constant amount suitable for a set temperature and thereafter increasing the fuel supply gradually and also gradually decreasing the amount of gas supply which contains oxygen for burner combustion. CONSTITUTION:In the initial stage (t0-t1) of temperature rising the amount of fuel supply is maintained at a first set amount (Q1) suitable for the condition in which the temperature in a furnace becomes a second set temperature (T2). The amount of gas supply which contains oxygen for combustion is decreased from a first set amount (Q2) to a third set amount (Q3) and a high temperature gas, with its temperature being raised as the temperature in the furnace rises, is generated as much as possible to suppress increase in heat loss by a high temperature in the exhaust gas for the temperature in the furnace, and an object to be heated is convection-heated with ample strirring of the inside of the furnace with high temperature combustion gas. As a result of this, in the time from starting combustion to the temperature rising in the furnace to a first set temperature it is always possible to reduce waste of the fuel and increase total heat efficiency satsifactorily.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for controlling the amount of fuel supplied to the burner and the amount of oxygen-containing gas supplied for combustion when raising the temperature inside the furnace to a first set temperature by a burner. The present invention relates to a method for controlling temperature inside a furnace.

[Prior art]

Conventionally, as shown in Fig. 4, the amount of fuel supplied to the burner and the amount of oxygen-containing gas supplied to the burner are gradually increased at a nearly constant ratio suitable for combustion throughout the temperature rise (from width to stage 5). , wasted fuel due to supplying excessive fuel considering the temperature inside the furnace.

[Problem that the invention seeks to solve]

However, since both the amount of fuel supplied and the amount of oxygen-containing gas supplied for combustion decrease at the beginning of temperature rise, the amount of high-temperature combustion gas generated is small, and the stirring in the furnace by high-temperature combustion gas is insufficient. As a result, the convection heat transfer efficiency to the objects to be heated in the furnace deteriorates, and the overall thermal efficiency does not improve much.
Rather, it caused problems in terms of heating performance.

Furthermore, in the early stages of temperature rise, even if the fuel supply amount is finely adjusted using pulp and the combustion oxygen-containing gas supply amount is finely adjusted using a damper to adjust the temperature, problems may occur due to the characteristics of the pulp, damper, or controller. However, since the rate of fluctuation in the supply amount of fuel and oxygen-containing gas for combustion is large, there is a great risk that the temperature change in the furnace will greatly exceed the desired range, and it has been impossible or extremely difficult to accurately control the temperature inside the furnace.

An object of the present invention is to improve heating performance in the initial stage of temperature rise and to accurately and easily adjust the temperature inside the furnace, while making use of the conventional technical idea of suppressing fuel waste. .

[Means to solve the problem]

The characteristic means of the present invention is that when the temperature inside the furnace is raised to a first set temperature by a burner, the amount of fuel supplied to the burner is increased until the temperature inside the furnace reaches a second set temperature in the middle of heating. Initially, the oxygen-containing gas for combustion in the burner is maintained almost constant at the first set amount corresponding to the second set temperature, and then gradually increased from the first set amount to the fifth set amount. The supply amount is gradually decreased from the second set amount to the third set amount at the initial stage of the temperature increase, and thereafter gradually increased from the third set amount to the fourth set amount, and the operation thereof is as follows. The effect is as follows.

[For production]

As shown in Figure 3, at the beginning of the temperature increase (see Figure 3).

~11), the fuel supply amount is maintained at the first set amount (Ql) commensurate with the state in which the temperature inside the furnace reaches the second set temperature (T2) corresponding to the time (tl), and the combustion oxygen is Gradually reduce the content gas supply amount from the second set amount (q2) to the third set amount (Q3), gradually raise the temperature of the high-temperature combustion gas as the temperature inside the furnace increases, and generate as large a amount as possible. This suppresses the increase in heat loss caused by the exhaust gas becoming too hot compared to the furnace temperature of the high-temperature combustion gas,
In addition, the object to be heated is efficiently convectively heated by sufficient stirring in the furnace using a large amount of high-temperature combustion gas.

In addition, to adjust the temperature inside the furnace, the amount of fuel supplied is kept constant and the calorific value is not changed, but only the amount of oxygen-containing gas that is supplied in large quantities is changed, and the change in wet coal To accurately and easily raise the furnace temperature as desired by reducing hunting and chattering in furnace temperature control.

After that (t1 to tx), both the fuel supply amount and the combustion oxygen-containing gas supply amount are gradually increased to a state where the temperature inside the furnace reaches the first set temperature (T1) which is the temperature increase target tlK The amount is increased to an appropriate maximum amount (q4) or (Q5) to suppress heat loss due to excessively high temperature of the high-temperature combustion gas and to maintain efficient convective heating by a large amount of high-temperature combustion gas.

〔Effect of the invention〕

As a result, from the start of combustion until the temperature inside the furnace rises to the desired first set temperature, the convection heating of the heated object is always performed with high efficiency, minimizing fuel waste as much as possible. This makes it possible to sufficiently improve the overall thermal efficiency, and to accurately raise the temperature inside the furnace over a predetermined period of time, thereby ensuring a good heat treatment.

〔Example〕

Next, examples will be shown.

First, the equipment used in Section 14 will be explained.

A first pipe line (3) that supplies gas fuel and a second pipe line (4) that supplies combustion air to the burner (2) of the heating furnace (t).
, the pressure equalizing valve (5) and the first flow rate sensor (SO) are connected to the first pipe line (3), and the damper (6) and the second flow rate sensor (S5) are connected to the second pipe line (4). A temperature sensor (S3) for detecting the temperature inside the furnace is installed at heating furnace +1+.

A setting device (7) includes a programmer (K) that sets changes in the temperature inside the furnace, and a determination means (7b) that determines the control form based on information from the programmer (7a) and the temperature sensor (S5).
and a determination means (7b) and a first flow rate sensor (Sl).
The first program controls the damper (6) using information from
A controller (8) is provided, and the determining means (7b) and the first and second
A second controller that programmatically controls the damper (6) and servo motor (9) using information from the flow rate sensor (81) = (s2).
A controller (lO) is provided, and the second flow rate sensor (S2) is automatically operated by the second controller (t0) of the servo motor (9).
) of the pressure equalizing valve (5) via the hook and pinion mechanism Qη, the tension spring (5a), and the rod (5b) so that the detected flow rate by the
Tension spring (5a) so that the opening can be adjusted
The structure is such that the acting force can be maintained constant in the set state.

The downstream side of the damper (6) and the first pressure chamber (
5d) is connected by a pressure impulse pipe (2), and a second pressure chamber (50) is separated from the first pressure chamber (5d) by a first diaphragm (5) linked to a valve body (5C). A second diaphragm (5h) connects the downstream side of (5C) with a pressure path (52) and isolates the upstream side of the valve body (5C) and the second pressure chamber (5f).
is linked to the valve body (5C), and the tensile spring (5a)
With the acting force constant, the air-fuel ratio is automatically adjusted by the balance of the pressure from the impulse pipe (6), the pressure upstream of the valve body (5C), and the pressure downstream of the valve body (5C). It is configured to be maintained within a set range.

Next, a method for controlling the temperature inside the furnace will be explained.

As shown in Figure 2, the temperature inside the furnace is set to the first set temperature (T1).
In order to raise the temperature to , set the correlation between the furnace temperature and time in the programmer (7a).

After igniting the burner (2), at the initial stage of heating up (to-tl) until the furnace temperature detected by the temperature sensor (S3) reaches the second set temperature (T5) in the middle of heating up, the determining means (7
B assistant) and the second controller (issue an operation command only for t01,
As shown in Figure 3, the gas fuel supply amount is adjusted to the second set temperature (
The first set amount (Ql) corresponding to T is maintained almost constant by the action of the servo motor (9), and the second set amount of combustion air is
damper (6) from the set amount (Q5) to the third set amount (Qs).
), the temperature of the high-temperature combustion gas from the burner (2) is increased in proportion to the rise in the furnace temperature.

The furnace temperature from the temperature sensor (S3) is the second set temperature (
When T5) is reached, the determining means (7b)7. The controller issues an operation command to the first controller (8) and a stop command to the second controller (lO), and thereafter, the temperature in the furnace from the temperature sensor (S3) reaches the first set temperature (T1). The temperature rising period (tx ~
At t2), as shown in Fig. 3, the combustion air supply amount is gradually increased from the third set amount (q3) to the fourth set amount (Q5) by operating the damper (6), and the fuel supply amount is increased. 1st
Impulse pipe (2) from the set amount (ql) to the fifth set amount (Q4)
The air-fuel ratio is gradually increased by operating the pressure equalizing valve (5), and the air-fuel ratio is kept almost constant as the temperature inside the furnace increases.
Increase the amount of heat generated by the burner (2).

The furnace temperature measured by the temperature sensor (8,) is the first set temperature (
When T1) is reached, the first controller (8) operates the damper (6) to maintain the furnace temperature at a substantially constant temperature for a set time, or immediately closes the damper (6) completely. and extinguish the burner (2).

[Another example]

Next, another example will be shown.

In order to raise the temperature inside the furnace to the first set temperature (T1), the shape of the temperature rise curve can be appropriately selected.
T5) can be appropriately set depending on the convection heating characteristics of the object to be heated in the furnace.

The first set amount (Q5) and the fifth set amount (QS) of the fuel supply amount
) can be appropriately selected according to the calorific value of the fuel, air ratio, and other requirements, and the second set amount (Q2), third set amount (Q3), and fourth set amount ( Q4)
can be selected depending on combustion stability, convective heating characteristics, air ratio, and other requirements. Then, the initial stage of temperature increase (to
The end point of steps 11) to 11) may be set by a timer.

The type of fuel can be selected from various gas fuels such as city gas, natural gas, propane gas, various oils, and other suitable fuels.The type of burner (2) also depends on the type of fuel, furnace structure, and other conditions. You can choose appropriately.

Oxygen-enriched air, oxygen, etc. may be used instead of air.
These are collectively called oxygen-containing gases for combustion.

The specific configuration for changing the fuel supply amount and the combustion oxygen-containing gas supply amount can be changed as appropriate, and the setting device (7)
, the first and second controller +81, the specific configuration of flo+, the program type in automatic control, and the specific form of other dispatch control means can be selected as appropriate. may be adjusted.

[Brief explanation of drawings]

Figures 1 to 3 show examples of the present invention, Figure 1 is a conceptual diagram of the equipment used, Figure 2 is a graph showing changes in furnace temperature, and Figure 3 is fuel supply amount and combustion air supply. It is a graph showing changes in quantity. FIG. 4 shows a conventional example and is a graph corresponding to FIG. 3. (2)・・・・・・Burna. Agent Patent Attorney Osamu Kitamura (IJ Ka1gu)

Claims (1)

[Claims] The temperature inside the furnace is set to the first set temperature (T_1) by the burner (2).
A furnace temperature control method for adjusting the amount of fuel supplied to the burner (2) and the amount of oxygen-containing gas for combustion when raising the temperature to
During the initial stage of temperature rise (t_0 to t_1) until the temperature inside the furnace reaches the second set temperature (T_2) during heating, the first set amount (Q_1) corresponding to the second set temperature (T_2) is almost constant. and thereafter (t_1 to t_2), the first set amount (Q_1) to the fifth set amount (Q_5)
The amount of oxygen-containing gas supplied to the burner (2) is gradually increased during the initial stage of temperature rise (t_0 to t_1).
The set amount (Q_2) is gradually decreased to the third set amount (Q_3), and thereafter (t_1 to t_2), the third set amount (Q_3) is gradually increased to the fourth set amount (Q_4). How to adjust the temperature inside the furnace.