JPH073283B2 - heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention connects a first pipeline for supplying a fuel and a second pipeline for supplying an oxygen-containing gas for combustion to a burner, A pressure equalizing valve in the pipeline and a damper in the second pipeline,
The pressure equalizing valve and the second conduit are connected by a pressure guiding pipe, and an operating pressure for maintaining the ratio of the fuel supply amount and the oxygen-containing gas supply amount for combustion substantially constant is applied to the pressure equalizing valve by the pressure guiding pipe. And a heating furnace formed to do so.

[Prior art]

Conventionally, as shown in FIG. 4, by applying an operating pressure from the pressure guiding pipe (12) to the pressure equalizing valve (5), as shown in FIG. 5, the entire temperature is raised (t _{0 to} t ₂ ). Burner (2)
The fuel supply amount (Q _{6 to} Q ₅ ) and the oxygen-containing gas supply amount for combustion (Q _{7 to} Q ₄ ) to the combustion chamber are gradually increased at an almost constant ratio suitable for combustion. The waste of fuel due to the supply of fuel was suppressed.

[Problems to be solved by the invention]

However, since both the fuel supply amount and the oxygen-containing gas supply amount for combustion decrease in the initial stage of temperature rise, the generation amount of the high temperature combustion gas decreases, and the agitation in the furnace by the high temperature combustion gas becomes insufficient, The convective heat transfer efficiency to the object to be heated in the furnace deteriorates, and overall the heat efficiency does not improve so much,
Rather, there was a problem in heating performance.

In addition, even if the amount of combustion oxygen-containing gas supplied is finely adjusted with a damper at the initial stage of temperature rise, due to the characteristics of the damper or controller, the supply of fuel and combustion oxygen-containing gas The rate of change in the amount became large, and there was a great risk that the temperature change in the furnace greatly exceeded the desired range, and accurate temperature control in the furnace was impossible or extremely difficult.

An object of the present invention is to make it possible to improve the heating performance in the initial stage of temperature increase and to accurately and easily control the temperature inside the furnace while utilizing the conventional technical idea for suppressing the waste of fuel as it is, and This is to prevent the fuel loss from increasing.

[Means for solving problems]

The characteristic means of the present invention is the first fuel supply valve having a pressure equalizing valve.
A damper is provided in the pipe line, and based on the information from the temperature sensor for the inside of the furnace, the fuel is set from the first set amount to the second set amount in the initial stage of temperature increase until the temperature inside the furnace reaches the second set temperature during the temperature increase. So that the opening amount of the damper of the first pipeline is increased so that the second set temperature is reached during the temperature rising period from the second set temperature to the first set temperature. A first controller for maintaining the damper of the first conduit at a degree of opening equal to or more than a commensurate degree of opening is provided, and based on the information from the temperature sensor, the oxygen-containing gas supply amount for combustion is the So that the third set amount corresponding to the second set amount is maintained, and the combustion oxygen-containing gas supply amount is gradually increased from the third set amount to the fourth set amount during the temperature rising period. A second line damper for the oxygen-containing gas for combustion that applies an operating pressure to the pressure equalizing valve The lies in the provision of the second control unit for automatic operation, the effects thereof are as follows.

[Operation] That is, in the initial stage of temperature increase (t _{0 to} t ₁ ), the supply of the oxygen-containing gas for fuel is maintained at the third set amount (Q ₃ ) by the operation of the second controller, and the pressure equalizing valve is operated. The fuel supply amount is maintained at an opening degree commensurate with the second set amount (Q ₂ ), and then the opening degree of the damper of the first pipeline is gradually increased by the first controller.

In more detail, as shown in FIG. 3, heated initial (t ₀
In ~t _1), maintaining the combustion oxygen containing gas supply amount to the furnace temperature time (t ₁₎ at the corresponding second set temperature (T ₂ in a state to be) commensurate ivy third predetermined amount (Q ₃₎ And, the fuel supply amount is gradually increased from the first set amount (Q ₁ ) to the second set amount (Q ₂ ) to gradually raise the temperature of the high temperature combustion gas as the furnace temperature rises. It suppresses the increase of heat loss due to the high temperature of the high temperature combustion gas because the high temperature combustion gas is too high compared to the temperature inside the furnace, and the sufficient in-furnace agitation with the large amount of high temperature combustion gas. Efficiently heats the object to be heated by convection.

In addition, in controlling the temperature inside the furnace, the supply amount of oxygen-containing gas for combustion is maintained excessively and constantly, only the fuel supply amount is changed, the fuel consumption amount is reduced, and the fuel supply amount is changed. Reduces the temperature change, eliminates hunting and chattering in controlling the temperature inside the furnace, and raises the temperature inside the furnace accurately and easily as desired.

Then, during the temperature rising period (t _{1 to} t ₂ ), the damper of the first pipeline is maintained at a large opening by the action of the first controller, and the fuel supply amount is adjusted by the pressure equalizing valve, Moreover, the opening degree of the damper of the second pipeline is gradually increased by the second controller.

More specifically, as shown in FIG. 3, the temperature rising period (t ₁ ~
At t ₂ ), both the fuel supply amount and the combustion oxygen-containing gas supply amount are gradually increased so that the furnace temperature reaches the first set temperature (T ₁ ) which is the heating target, and the maximum amount is achieved. (Q ₄ )
Or (Q ₅ ) to suppress heat loss due to excessive supply of high temperature combustion gas, and perform efficient convection heating with a large amount of high temperature combustion gas.

〔The invention's effect〕

As a result, not only can fuel be wasted as little as possible from the start of combustion until the furnace temperature is raised to the desired first set temperature, but also convection heating of the object to be heated can be performed efficiently. , A heating furnace that is capable of sufficiently improving the overall thermal efficiency, and that the temperature inside the furnace can be raised exactly as specified to ensure a good heat treatment, and that the heating furnace has excellent performance and operating costs. Can be provided.

〔Example〕

 Next, examples will be shown.

As shown in FIG. 1, in the burner (2) of the heating furnace (1),
The first pipeline (3) for supplying gas fuel and the second pipeline (4) for supplying combustion air are connected to each other, and the pressure equalizing valve (5) and the damper (11) are connected to the first pipeline (3). Further, the damper (6) is provided in the second conduit (4), and the temperature sensor (S) for detecting the temperature inside the furnace is provided in the heating furnace (1).

To form the pressure equalizing valve (5), the first pressure chamber (5d) and the second pressure chamber (5f) are formed by the first diaphragm (5e) and the second pressure chamber (5f) and the valve body (5c) are formed. The upstream side is isolated by the second diaphragm (5h), the tension spring (5a) acting on the first diaphragm (5e) is provided, and the first and second diaphragms (5e), (5h) are connected by the rod (5b). Disc (5c)
In such a state that the acting force of the tension spring (5a) is constant, the downstream side of the valve body (5c) is connected to the second pressure chamber (5f) by the pressure guiding path (5g). , Pressure from the pressure guiding pipe (12) connected to the second pipe line (4), valve body (5c)
The air-fuel ratio is automatically maintained within the set range by the balance between the pressure on the upstream side and the pressure on the downstream side of the valve element (5c).

A programmer (7a) that sets the change in furnace temperature, and
The setting device (7) is provided with the judging means (7b) for judging the control form based on the information from the programmer (7a) and the temperature sensor (S), and the information from the judging means (7b) is used to identify the first conduit (3). A first controller (8) for automatically operating the damper (11) and a second controller (10) for automatically operating the damper (6) of the second pipeline (4) are provided and the furnace is installed as shown below. The internal temperature is configured to be automatically adjusted according to a program.

In other words, as shown in FIG. 2, when the temperature inside the furnace is set to the programmer (7a) in order to raise the temperature inside the furnace to the first set temperature (T ₁ ), the burner (2) turns on. After ignition, initial temperature rise (t _{0 to} t ₁ ) until the temperature inside the furnace from the temperature sensor (S) reaches the second set temperature (T ₂ ) during the temperature rise
In the above, based on a command from the judging means (7b) to the first and second controllers (8), (10), the opening degree of the damper (11) of the first conduit (3) is gradually increased, As shown in FIG. 3, the fuel supply amount is gradually increased from the first set amount (Q ₁ ) to the second set amount (Q ₂ ) and the damper (6) of the second pipeline (4) is set. in the set opening, as shown in FIG. 3, to maintain the combustion air supply amount second set amount of fuel (Q ₂₎ to commensurate ivy third set amount (Q _3), increase in the furnace temperature In view of the above, the temperature of the high temperature combustion gas by the burner (2) is increased.

Further, based on a command from the determination means (7b) to the first and second controllers (8), (10), the temperature inside the furnace from the temperature sensor (S) reaches the second set temperature (T ₂ ). , First conduit (3)
Open the damper (11) of the second opening to a setting opening equal to or larger than the opening corresponding to the second setting temperature (T ₂ ), and gradually increase the opening of the damper (6) of the second pipeline (4), The opening of the pressure equalizing valve (5) is gradually increased, the opening of the pressure equalizing valve (5) is gradually increased, and as shown in FIG. 3, the temperature inside the furnace from the temperature sensor (S) is set to the first setting. up to reach the temperature (T ₁₎ Noboru Yutakaki (t ₁ ~
In t _2), the fifth set of weight third set the combustion air supply amount (fourth predetermined amount from Q ₃₎ (Q ₄₎ gradually increases in the fuel supply amount first set amount (Q ₁₎ The amount of heat generation of the burner (2) is increased while the air-fuel ratio is kept almost constant in proportion to the rise in the temperature inside the furnace, while the amount (Q ₅ ) is gradually increased. Then, when the temperature inside the furnace by the temperature sensor (S) reaches the first set temperature (T ₁ ), the damper is controlled by the second controller (10) to maintain the temperature inside the furnace at a substantially constant temperature for the set time. (6) is operated, or the damper (6) is immediately fully opened to extinguish the burner (2).

[Another embodiment]

 Next, another embodiment will be described.

The shape of the temperature rising curve can be appropriately selected to raise the temperature in the furnace to the first set temperature (T ₁ ), and the second set temperature (T ₂ ) is the convection heating characteristic for the object to be heated in the furnace. It can be set appropriately according to.

The first set amount (Q ₁ ) and the fifth set amount (Q ₅ ) of the fuel supply amount can be set appropriately in accordance with the heat generation amount of the fuel, the air ratio, and other necessary conditions. The second set amount (Q ₂ ), the third set amount (Q ₃ ), and the fourth set amount (Q ₄ ) can be selected in consideration of combustion stability, convection heating characteristics, air ratio, and other necessary conditions. The end point of the initial stage of temperature rise (t _{0 to} t ₁ ) may be set by a timer.

The type of fuel can be selected from various gas fuels such as city gas, natural gas and propane gas, various oils, and other suitable ones. The burner (2) type can be selected depending on the type of fuel, furnace structure,
It can be appropriately selected according to other conditions.

Instead of air, oxygen-enriched air or oxygen may be used,
They are collectively referred to as the oxygen-containing gas for combustion.

The specific structures of the dampers (6), (11), the pressure equalizing valve (5), etc. can be changed as appropriate, and the specific configurations of the setter (7), the first and second controllers (8), (10). , A program type in automatic control, and other specific forms of automatic control means can be selected appropriately.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention, FIG. 1 is a conceptual diagram of the furnace, FIG. 2 is a graph showing temperature change in the furnace, and FIG.
The figure is a graph showing changes in the fuel supply amount and the combustion air supply amount. 4 and 5 show a conventional example, FIG. 4 is a schematic view of a furnace, and FIG. 5 is a graph corresponding to FIG. (2) …… Burner, (3) …… First pipeline, (4) …… Second pipeline, (5) …… Equalization valve, (6) …… Damper,
(8) …… First controller, (10) …… Second controller, (11)
…… Damper, (12) …… Impulse pipe.

Continuation of front page (56) References JP-A-62-248915 (JP, A) JP-A-62-248916 (JP, A) JP-A-61-72921 (JP, A) JP-B-58-23448 (JP , B2)

Claims (1)

[Claims] 1. A first conduit (3) for supplying a fuel and a second conduit (4) for supplying an oxygen-containing gas for combustion are connected to a burner (2), and the first conduit (3) is provided. ) Is provided with a pressure equalizing valve (5) and the second pipe (4) is provided with a damper (6), and the pressure equalizing valve (5) and the second pipe (4) are connected by a pressure guiding pipe (12). A heating furnace formed so that an operation pressure for maintaining a ratio of a fuel supply amount and a combustion oxygen-containing gas supply amount substantially constant is applied to the pressure equalizing valve (5) by the pressure guiding pipe (12), , A damper (11) is provided in the first pipe line (3), and the temperature in the furnace reaches the second set temperature (T ₂ ) in the middle of heating based on the information from the temperature sensor (S) for the furnace. In the initial stage of temperature rise (t _{0 to} t ₁ ) until the fuel is gradually increased from the first set amount (Q ₁ ) to the second set amount (Q ₂ ), the first pipeline (3) Damper (11) an increasing opening, and wherein the temperature Yutakaki from the second set temperature (T ₂₎ until it reaches the first set temperature (T ₁₎ (t ₁ ~t _2), the second set temperature The damper (11) of the first pipeline (3) above the opening corresponding to (T ₁ ).
A first controller (8) for maintaining the above is provided, and based on the information from the temperature sensor (S), the oxygen-containing gas supply amount for combustion is the first of the fuel at the initial temperature rising (t _{0 to} t ₁ ). 2 set amount (Q ₂₎ to so as to maintain the commensurate ivy third set amount (Q _3), and the temperature Yutakaki (t ₁ ~t ₂₎ the combustion oxygen containing gas supply amount is the third set amount (Q ₃₎ from as gradually increases in the fourth set amount (Q _4), provided a second controller for automatically operating the (10) the damper (6) of the second conduit (4) There is a heating furnace.