JP2014238243A - Single end type radiant tube burner and combustion method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single end type radiant tube burner which can reduce a cost and make combustion operation efficient while suppressing the increase of a running cost and deterioration of durability.SOLUTION: A combustion control means H, when combustion starting instruction is instructed, starts heating actuation of an electric heating means 5 which heats a base end side combustion chamber Ne communicated to a base end part of an internal pipe 2 disposed on an inner part of an external pipe 1 while stopping the supply of mixed gas from a mixed gas supply part K, thereafter, when an inner temperature of the base end side combustion chamber Ne gets to a preset combustion starting temperature higher than an ignition temperature of gas fuel, or more, executes such preliminary combustion treatment that the mixed gas supply part K is subjected to supply actuation while performing supply for base end side combustion and, when the inner temperature of the top end side combustion chamber Ns between the top end part of the external pipe 1 and the top end part of the internal pipe 2 gets to the preset combustion starting temperature or more after execution of the preliminary combustion treatment, executes such main combustion treatment that the mixed gas supply part K is subjected to supply actuation while performing supply for top end side combustion.

Description

In the present invention, an inner tube having both ends opened is provided inside the outer tube whose front end is blocked,
The present invention relates to a single-ended radiant tube burner in which an exhaust gas passage for allowing combustion gas to flow from the distal end side to the proximal end side of the outer tube is formed between the outer tube and the inner tube, and a combustion method thereof.

Such a single-ended radiant tube burner is installed in a heating furnace, a heat treatment furnace, or the like, and is used for indirectly heating the space in the furnace.
Conventionally, a single-ended radiant tube burner generally uses an inner pipe as a combustion space, supplies gas fuel and combustion air to the combustion space, and forms a combustion flame in the inner pipe. It is comprised so that it may burn (for example, refer patent document 1).

In Patent Document 1, the outer tube and the inner tube are formed of a ceramic material (silicon carbide), but the outer tube and the inner tube are often formed of a metal material (for example, a stainless material).
Further, in the single-ended radiant tube burner of Patent Document 1, detailed description is omitted, but combustion air or gas fuel and combustion air for supplying the combustion gas flowing in the exhaust gas passage to the combustion space It is often discharged after passing through the heat exchanger for preheating the mixed gas and preheating the combustion air or the mixed gas.

  Further, although not described in Patent Document 1, conventionally, an igniter that ignites gas fuel supplied to the combustion space together with the combustion air, or that the gas fuel supplied to the combustion space is in an ignition state. An ignition detection sensor to be detected is provided in the combustion space, and gas fuel ignition and ignition confirmation are performed. In addition, when the ignition detection sensor detects misfire during combustion, supply of gas fuel is stopped. A safety control will be provided.

Further, although not described in Patent Document 1, when gas fuel is burned in the combustion space, so-called pre-purging is performed in which combustion air is supplied to the combustion space in advance and discharged outside through the exhaust gas passage. After execution, gas fuel is supplied to the combustion space to start combustion.
In addition, such pre-purge is also performed at the time of reignition such as when reigniting after a misfire occurs during combustion, or when reigniting after temporarily suspending combustion for controlling the furnace temperature. Become.

JP 2002-022110 A

  In single-ended radiant tube burners, it is desirable to reduce the cost by omitting the ignition detection sensor, and reigniting when reigniting after temporarily stopping combustion to control the furnace temperature. It is desired to improve the efficiency of the combustion operation by omitting the pre-purge at the time.

  As a means for reducing the cost and improving the efficiency of the combustion operation, for example, an electric heater is disposed on the outer peripheral portion of the inner pipe, and the inner pipe is heated by the electric heater so that the combustion formed inside the inner pipe After heating the internal temperature of the space to a set combustion start temperature that is higher than the ignition temperature of the gas fuel, supplying the gas fuel and combustion air to the combustion space to start combustion, an ignition detection sensor or It may be possible to reduce the cost by omitting the igniter and to improve the efficiency of the combustion operation by omitting the pre-purge at the time of reignition.

That is, if the internal temperature of the combustion space is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, the gas fuel will spontaneously ignite if the gas fuel and combustion air are supplied to the combustion space. Therefore, the ignition detection sensor and the igniter can be omitted.
In addition, if the internal temperature of the combustion space is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel at the time of re-ignition, such as when re-igniting after temporarily stopping combustion for controlling the furnace temperature In addition, since there is no explosion ignition caused by unburned gaseous fuel and combustion air remaining in the combustion space, pre-purge at the time of re-ignition can be omitted.

By the way, even in the description of “Safety Technical Indicators for Industrial Gas Combustion Equipment: Japan Gas Association January 2009”, the internal temperature of the combustion space is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel. By doing so, a combustion monitoring device such as an ignition sensor can be omitted, and pre-burging during reignition can be omitted.
Therefore, by setting the internal temperature of the combustion space to a set combustion start temperature higher than the ignition temperature of the gas fuel, the ignition detection sensor and the igniter are omitted to reduce the cost, and the pre-purge at the time of reignition is omitted. Thus, while improving the efficiency of combustion operation, it can be used as equipment that meets the safety technology index of the Japan Gas Association.

  However, a configuration in which an electric heater is disposed on the outer peripheral portion of the inner pipe and the internal temperature of the combustion space formed inside the inner pipe is raised to a set combustion start temperature higher than the ignition temperature of the gas fuel, It was not practical due to the large power consumption of the electric heater and the fact that the electric heater was easily burned out.

That is, when the internal heater is heated by operating the electric heater disposed on the outer periphery of the inner pipe to raise the internal temperature of the combustion space formed inside the inner pipe to a set combustion start temperature or higher. Due to the large volume of the combustion space formed inside the inner pipe, there is a disadvantage that the power consumption of the electric heater becomes considerably large and the running cost increases.
Incidentally, the heat transferred to the inner pipe tends to be radiated in a large amount from the inner pipe to the outside while being conducted to the entire inner pipe. From this point as well, the temperature of the combustion space exceeds the set combustion start temperature. In order to raise, the power consumption of the electric heater was considerably increased.

  When combustion of gas fuel is started in the combustion space, the high-temperature combustion gas flows through the exhaust gas passage between the outer pipe and the inner pipe, and the electric heater uses the high-temperature combustion gas. There was an inconvenience that the durability of the electric heater was lowered, such as heating and burning.

The present invention has been made in view of the above circumstances, and its purpose is to provide a single end capable of reducing the cost and improving the efficiency of combustion operation while suppressing an increase in running cost and a decrease in durability. The type radiant tube burner is provided.
Another object is to provide combustion of a single-ended radiant tube burner capable of reducing the cost and improving the efficiency of combustion operation while suppressing an increase in running cost and a decrease in durability.

The single-ended radiant tube burner of the present invention is provided with an inner tube having both ends opened inside the outer tube whose front end is closed,
An exhaust gas passage is formed between the outer tube and the inner tube to allow combustion gas to flow from the distal end side to the proximal end side of the outer tube.
A base end side combustion chamber communicating with the base end portion of the inner pipe is provided;
Between the distal end portion of the outer tube and the distal end portion of the inner tube, a distal end side combustion chamber having a larger volume than the proximal end side combustion chamber is formed,
A base end jetting part is provided for injecting a mixed gas of gas fuel and combustion air into the base end side combustion chamber to form a combustion flame in the base end side combustion chamber;
A mixed gas supply unit that supplies a mixed gas of gas fuel and combustion air injects the mixed gas into the base end side combustion chamber by the base end side jet unit to form a combustion flame in the base end side combustion chamber A base-end combustion supply state, and a larger amount of mixed gas than the base-end combustion supply state is caused to flow into the inner pipe through the base-end combustion chamber in a non-combustion state. It is configured to be switchable to a front-end combustion supply state that is jetted from the front end of the inner pipe to the front-end combustion chamber and forms a combustion flame in the front-end combustion chamber,
Electric heating means for heating the base end side combustion chamber is provided on the outer periphery of the base end side combustion chamber,
Combustion control means
When a combustion start command is issued, the heating operation of the electric heating means is started in a state where the supply of the mixed gas from the mixed gas supply unit is stopped, and then the internal temperature of the proximal combustion chamber is A pre-combustion process for supplying and operating the mixed gas supply unit in the base-side combustion supply state when the set combustion start temperature is higher than the ignition temperature of the gas fuel; and
After starting execution of the preliminary combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature, the main combustion process for supplying and operating the mixed gas supply unit in the front end side combustion supply state It is characterized by being configured to execute.

That is, when the combustion control command is instructed, the combustion control means executes the preliminary combustion process, and then executes the main combustion process.
In the preliminary combustion process, with the supply of the mixed gas from the mixed gas supply unit stopped, the heating operation of the electric heating means is started to increase the internal temperature of the proximal combustion chamber, and then the proximal end When the internal temperature of the side combustion chamber becomes equal to or higher than the set combustion start temperature that is higher than the ignition temperature of the gas fuel, a process for supplying and operating the mixed gas supply unit in the base end combustion supply state is performed.

  The base-end combustion supply state is a state in which the mixed gas is supplied to the base-end side combustion chamber by injecting the mixed gas into the base-end side combustion chamber by the base-end-side ejection portion. In the combustion process, when the mixed gas is ejected to the proximal end side combustion chamber by the proximal end side ejection portion, the internal temperature of the proximal end side combustion chamber is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel. The mixed gas ejected to the proximal end side combustion chamber will naturally start to burn.

  Further, when the mixed gas is jetted into the base end side combustion chamber by the base end side jetting portion, the internal temperature of the base end side combustion chamber already having a set combustion start temperature higher than the ignition temperature of the gas fuel is already set. Since no unburned gas fuel remains inside, even if the mixed gas is ejected to the proximal end side combustion chamber by the proximal end side ejecting portion, no explosion ignition occurs.

  In the main combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, a process for supplying the mixed gas supply unit in the front end side combustion supply state is performed.

  In the front-end combustion supply state, a larger amount of mixed gas is flowed into the inner pipe through the base-end combustion chamber in the non-combustion state than in the base-end combustion supply state, and the mixed gas is supplied to the front end from the front end of the inner pipe. In this combustion process, when the mixed gas is ejected from the front end of the inner tube to the front side combustion chamber, the mixed gas is supplied so as to be ejected into the side combustion chamber and form a combustion flame in the front end side combustion chamber. Since the internal temperature of the front end side combustion chamber is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, the mixed gas injected into the front end side combustion chamber starts to combust naturally.

  In addition, when the mixed gas is ejected from the tip of the inner pipe to the tip side combustion chamber, the inside temperature is already in the tip side combustion chamber where the internal combustion temperature is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel. Since no unburned gas fuel remains, even if the mixed gas is ejected from the distal end portion of the inner tube to the distal combustion chamber, no explosion ignition occurs.

  As described above, according to the first characteristic configuration of the present invention, the preliminary combustion process and the main combustion process are sequentially performed, and when the mixed gas is ejected into the proximal combustion chamber in the preliminary combustion process. The internal temperature of the proximal combustion chamber is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, and when the mixed gas is jetted into the distal combustion chamber in this combustion processing, Since the internal temperature is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, an igniter and an ignition sensor are not required when the mixed gas is injected into the proximal combustion chamber or the distal combustion chamber for combustion. In addition, since there is no gas fuel remaining in the proximal combustion chamber or the distal combustion chamber during re-ignition, such as when re-igniting after temporarily stopping combustion to control the furnace temperature Omit pre-purge in It is kill the.

  The proximal-side combustion chamber burns a small amount of mixed gas in order to heat the internal temperature of the distal-end side combustion chamber to a set combustion start temperature or higher. Since the volume is smaller than the volume, the amount of heat generated by the electric heating means required for heating the internal temperature of the proximal combustion chamber to the set combustion start temperature or more is small, so the consumption of the electric heating means Electric power is reduced, and running costs can be reduced.

Further, since the combustion gas does not flow in the outer peripheral portion of the base end side combustion chamber, the electric heating means provided in the outer peripheral portion of the base end side combustion chamber can avoid being heated and burned by the combustion gas. Thus, the durability of the electric heating means can be improved.
In general, an electric heater is used as the electric heating means. In addition, for example, an electromagnetic that forms the wall of the combustion chamber on the base end side with a magnetic material and inductively heats the wall is formed. An induction heating device can also be used.

  In short, according to the first characteristic configuration of the present invention, it is possible to provide a single-ended radiant tube burner capable of reducing the cost and improving the efficiency of the combustion operation while suppressing an increase in running cost and a decrease in durability.

In addition to the first feature configuration described above, the second feature configuration of the single-ended radiant tube burner of the present invention includes:
The mixed gas supply unit is configured to inject the mixed gas from the base end side injection portion to the base end side combustion chamber in the supply state for the front end side combustion,
The relationship between the proximal end combustion supply state and the distal end combustion supply state is that the mixed gas is supplied in the proximal end combustion supply state, and a combustion flame is formed in the proximal end combustion chamber. When the state is changed to the front-end combustion supply state, the combustion flame formed in the base-end combustion chamber is set to be lifted to the front-end combustion chamber.

That is, the mixed gas is ejected from the proximal end ejection portion into the proximal end combustion chamber in both the proximal end combustion supply state and the distal end side combustion supply state.
Then, in the state where the mixed gas is supplied in the proximal end combustion supply state and the combustion flame is formed in the proximal end combustion chamber, when the state is changed to the distal end side combustion supply state, it is formed in the proximal end combustion chamber. The combustion flame is lifted to the tip side combustion chamber.

  In this way, the transition from the state in which the combustion flame is formed in the proximal combustion chamber and the combustion to the state in which the combustion flame is formed in the distal combustion chamber and the combustion is performed is performed while continuing the flame formation state. From, for example, a transition from a state in which a combustion flame is formed in the proximal combustion chamber to a combustion state to a state in which a combustion flame is formed in the distal combustion chamber and then is burned, compared to a case where a fire extinguishing state appears. Thus, while suppressing the inconvenience such as generation of unburned gas fuel in the mixed gas as much as possible, the combustion flame is formed in the distal combustion chamber from the state where the combustion flame is formed in the proximal combustion chamber and burned. Thus, it is possible to satisfactorily shift to the state of burning.

  In short, according to the second characteristic configuration of the present invention, in addition to the operational effects of the first characteristic configuration, the combustion flame is formed in the distal combustion chamber from the state in which the combustion flame is formed in the proximal combustion chamber and burned. Thus, it is possible to provide a single-ended radiant tube burner that can perform the transition to the combustion state satisfactorily while suppressing generation of unburned gas fuel as much as possible.

The third feature configuration of the single-ended radiant tube burner of the present invention is in addition to the first or second feature configuration described above,
A heat storage ceramic layer is provided at least on the inner surface side of the distal end portion of the outer tube.

  That is, since the ceramic layer for heat storage is provided on at least the inner surface side of the tip side portion of the outer tube, the heat of the tip side combustion chamber is stored in the ceramic layer for heat storage, thereby Since heat can be prevented from radiating to the outside from the distal end side portion of the outer tube, when performing the preliminary combustion process, the combustion gas formed in the combustion flame formed in the proximal end combustion chamber, The internal temperature of the front-end combustion chamber can be well raised to a set combustion start temperature higher than the ignition temperature of the gas fuel, and the combustion formed in the front-end combustion chamber during the execution of this combustion process Due to the heat generated by the flame, it is possible to satisfactorily maintain the internal temperature of the tip side combustion chamber at a set combustion start temperature higher than the ignition temperature of the gas fuel.

  In short, according to the third characteristic configuration of the present invention, the internal temperature of the front end side combustion chamber is raised to a set combustion start temperature higher than the ignition temperature of the gas fuel, or the internal temperature of the front end side combustion chamber is set to gas. It is possible to provide a single-ended radiant tube burner that can satisfactorily maintain a set combustion start temperature higher than the ignition temperature of the fuel.

In addition to any of the first to third feature configurations described above, the fourth feature configuration of the single-ended radiant tube burner of the present invention includes:
The electric heating means is an electric heater disposed in an outer peripheral portion of the proximal combustion chamber;
The heat insulation layer is provided in the state which covers the outer peripheral part of the said electric heater.

  That is, the electric heater disposed on the outer peripheral portion of the base end side combustion chamber heats the internal temperature of the base end side combustion chamber to be equal to or higher than the set combustion start temperature, and the outer peripheral portion of the electric heater is Since the heat insulating layer is provided in a covering state, the heat generated by the electric heater is suppressed from being radiated to the outside, and the inside of the proximal combustion chamber can be efficiently heated by the heat generated by the electric heater. .

  As described above, the heat generated by the electric heater can efficiently heat the inside of the proximal end side combustion chamber, so that the electric power consumed by the electric heater can be reduced to further reduce the running cost. it can.

  In short, the fourth feature configuration of the present invention provides a single-ended radiant tube burner capable of further reducing running costs in addition to the operational effects of any of the first to third feature configurations. it can.

In the combustion method of the single-ended radiant tube burner of the present invention, an inner tube having both ends opened is provided inside the outer tube whose front end is closed,
A combustion method for a single-ended radiant tube burner, in which an exhaust gas passage is formed between the outer tube and the inner tube to allow combustion gas to flow from the distal end side to the proximal end side of the outer tube,
A base end side combustion chamber communicating with the base end portion of the inner pipe is provided;
Between the distal end portion of the outer tube and the distal end portion of the inner tube, a distal end side combustion chamber having a larger volume than the proximal end side combustion chamber is formed,
A base end jetting part is provided for injecting a mixed gas of gas fuel and combustion air into the base end side combustion chamber to form a combustion flame in the base end side combustion chamber;
A mixed gas supply unit that supplies a mixed gas of gas fuel and combustion air injects the mixed gas into the base end side combustion chamber by the base end side jet unit to form a combustion flame in the base end side combustion chamber A base-end combustion supply state, and a larger amount of mixed gas than the base-end combustion supply state is caused to flow into the inner pipe through the base-end combustion chamber in a non-combustion state. It is configured to be switchable to a front-end combustion supply state that is jetted from the front end of the inner pipe to the front-end combustion chamber and forms a combustion flame in the front-end combustion chamber,
Electric heating means for heating the base end side combustion chamber is provided on the outer periphery of the base end side combustion chamber,
When starting the combustion, first, the heating operation of the electric heating means is started in a state where the supply of the mixed gas from the mixed gas supply unit is stopped, and then the internal temperature of the base end side combustion chamber is started. Is a set combustion start temperature higher than the ignition temperature of the gas fuel, perform a pre-combustion process to supply the mixed gas supply unit in the base-side combustion supply state,
After starting execution of the preliminary combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature, the main combustion process for supplying and operating the mixed gas supply unit in the front end side combustion supply state It is characterized by performing.

That is, when combustion is started, first, preliminary combustion processing is performed, and then main combustion processing is performed.
In the preliminary combustion process, with the supply of the mixed gas from the mixed gas supply unit stopped, the heating operation of the electric heating means is started to increase the internal temperature of the proximal combustion chamber, and then the proximal end When the internal temperature of the side combustion chamber becomes equal to or higher than the set combustion start temperature that is higher than the ignition temperature of the gas fuel, a process for supplying and operating the mixed gas supply unit in the base end combustion supply state is performed.

  The base-end combustion supply state is a state in which the mixed gas is supplied to the base-end side combustion chamber by injecting the mixed gas into the base-end side combustion chamber by the base-end-side ejection portion. In the combustion process, when the mixed gas is ejected to the proximal end side combustion chamber by the proximal end side ejection portion, the internal temperature of the proximal end side combustion chamber is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel. The mixed gas ejected to the proximal end side combustion chamber will naturally start to burn.

  Further, when the mixed gas is jetted into the base end side combustion chamber by the base end side jetting portion, the internal temperature of the base end side combustion chamber already having a set combustion start temperature higher than the ignition temperature of the gas fuel is already set. Since no unburned gas fuel remains inside, even if the mixed gas is ejected to the proximal end side combustion chamber by the proximal end side ejecting portion, no explosion ignition occurs.

  In the main combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, a process for supplying the mixed gas supply unit in the front end side combustion supply state is performed.

  In the front-end combustion supply state, a larger amount of mixed gas is flowed into the inner pipe through the base-end combustion chamber in the non-combustion state than in the base-end combustion supply state, and the mixed gas is supplied to the front end from the front end of the inner pipe. In this combustion process, when the mixed gas is ejected from the front end of the inner tube to the front side combustion chamber, the mixed gas is supplied so as to be ejected into the side combustion chamber and form a combustion flame in the front end side combustion chamber. Since the internal temperature of the front end side combustion chamber is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, the mixed gas injected into the front end side combustion chamber starts to combust naturally.

  In addition, when the mixed gas is ejected from the tip of the inner pipe to the tip side combustion chamber, the inside temperature is already in the tip side combustion chamber where the internal combustion temperature is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel. Since no unburned gas fuel remains, even if the mixed gas is ejected from the distal end portion of the inner tube to the distal combustion chamber, no explosion ignition occurs.

  As described above, according to the combustion method of the single-ended radiant tube burner of the present invention, the preliminary combustion process and the main combustion process are sequentially performed, and in the preliminary combustion process, the mixing is performed in the proximal combustion chamber. When injecting gas, the internal temperature of the base end side combustion chamber is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, and in the main combustion process, when injecting mixed gas into the front end side combustion chamber, Since the internal temperature of the front end side combustion chamber is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, when the mixed gas is jetted into the base end side combustion chamber or the front end side combustion chamber and burned, the igniter and An ignition sensor is not required, and gas fuel does not remain in the proximal-end combustion chamber or the distal-end combustion chamber, so re-ignition is required when reigniting after temporarily stopping combustion to control the furnace temperature. You can omit the pre-purge at the time of the fire.

  The proximal-side combustion chamber burns a small amount of mixed gas in order to heat the internal temperature of the distal-end side combustion chamber to a set combustion start temperature or higher. Since the volume is smaller than the volume, the amount of heat generated by the electric heating means required for heating the internal temperature of the proximal combustion chamber to the set combustion start temperature or more is small, so the consumption of the electric heating means Electric power is reduced, and running costs can be reduced.

Further, since the combustion gas does not flow in the outer peripheral portion of the base end side combustion chamber, the electric heating means provided in the outer peripheral portion of the base end side combustion chamber can avoid being heated and burned by the combustion gas. Thus, the durability of the electric heating means can be improved.
In general, an electric heater is used as the electric heating means. In addition, for example, an electromagnetic that forms the wall of the combustion chamber on the base end side with a magnetic material and inductively heats the wall is formed. An induction heating device can also be used.

  In short, according to the combustion method for a single-ended radiant tube burner according to the present invention, a single-ended radiant tube that can reduce costs and increase the efficiency of combustion operation while suppressing an increase in running cost and a decrease in durability. A burner burning method can be provided.

Schematic cross section of single-ended radiant tube burner Sectional drawing which shows the attachment part of a base end side ejection part Schematic sectional view showing combustion control mode

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Overall configuration of single-ended radiant tube burner)
As shown in FIG. 1, the single-ended radiant tube burner TB is provided in a state of penetrating a furnace wall W of a heating furnace or the like, and heats the interior space of the furnace. 1 and an inner tube 2 provided at both ends thereof provided inside the outer tube 1. The combustion gas flows between the outer tube 1 and the inner tube 2 from the distal end side to the proximal end side of the outer tube 1. An exhaust gas passage R is formed.

In the present embodiment, the outer tube 1 and the inner tube 2 are made of a metal material (for example, stainless steel), and a heat storage ceramic layer 3 is provided on the inner surface side of the distal end portion of the outer tube 1. Yes.
The ceramic layer 3 for heat storage is formed by pouring molten ceramic into the outer tube 1 made of a metal material, and then cooling it.
An exhaust gas outlet 4 for discharging combustion gas flowing through the exhaust gas passage R to the outside is formed at a portion located on the outer side of the furnace wall W of the outer tube 1.

A proximal end side combustion chamber Ne communicating with the proximal end portion of the inner tube 2 is provided adjacent to the proximal end portions of the outer tube 1 and the inner tube 2, and the distal end portion of the outer tube 1 and the distal end portion of the inner tube 2 are provided. The front end side combustion chamber Ns having a larger volume than that of the base end side combustion chamber Ne is formed.
A base end side injection section F for injecting a mixed gas of the gas fuel G and the combustion air A into the base end side combustion chamber Ne and forming a combustion flame in the base end side combustion chamber Ne includes a base end side combustion chamber. It is provided in a state adjacent to Ne, details of which will be described later.

  Incidentally, in the present embodiment, the outer tube 1 is configured using a tube having a nominal diameter of 40A, the inner tube 2 is configured using a tube having a nominal diameter of 25A, and the proximal combustion chamber Ne. However, it is configured using a pipe having a nominal diameter of 32A.

  A mixed gas supply unit K for supplying a mixed gas of the gas fuel G and the combustion air A is provided, and this mixed gas supply unit K ejects the mixed gas into the proximal end side combustion chamber Ne by the proximal end side ejection unit F. Then, a base side combustion supply state (see FIG. 3B) in which a combustion flame is formed in the base end side combustion chamber Ne, and a larger amount of mixed gas in the non-combustion state than the base end side combustion supply state. For the tip side combustion, which flows into the inner pipe 2 through the end side combustion chamber Ne and jets the mixed gas from the tip of the inner pipe 2 to the tip side combustion chamber Ns to form a combustion flame in the tip side combustion chamber Ns. It can be switched to a supply state (see FIG. 3C).

In the present embodiment, the mixed gas supply unit K supplies the mixed gas from the proximal-side ejection portion F to the proximal-side combustion chamber Ne in the distal-side combustion supply state in addition to the proximal-end combustion supply state. It is comprised so that it may eject.
The relationship between the supply state for the base end side combustion and the supply state for the front end side combustion is a state where the mixed gas is supplied in the base end side combustion supply state and the combustion flame is formed in the base end side combustion chamber Ne. When the state is changed to the front-end combustion supply state, the relationship is set such that the combustion flame formed in the base-end combustion chamber Ne is lifted to the front-end combustion chamber Ns.
The specific configuration of the mixed gas supply unit K will be described later.

  As shown in FIGS. 1 and 2, an electric heater 5 as an electric heating means for heating the base end side combustion chamber Ne is provided on the outer periphery of the base end side combustion chamber Ne, and the outer periphery of the electric heater 5 is A heat insulating layer 6 is provided so as to cover the part.

As shown in FIG. 1, the base end side temperature sensor P that detects the internal temperature of the base end side combustion chamber Ne is arranged in a state of passing through the base end side ejection portion F and extending to the base end side combustion chamber Ne. Yes.
A tip side temperature sensor Q that detects the internal temperature of the tip side combustion chamber Ns passes through the base end side ejection portion F, and passes through the inside of the base end side combustion chamber Ne and the inside of the inner pipe 2 to cause tip side combustion. It arrange | positions in the state extended to the chamber Ns.

(Configuration of the proximal end ejection part)
As shown in FIG. 2, a mixed gas supply chamber 7 to which a mixed gas is supplied from the mixed gas supply unit K is provided in a state communicating with the proximal end side combustion chamber Ne, and inside the mixed gas supply chamber 7, A proximal-side ejection portion F is provided.

Specifically, a partition wall 8 that crosses the mixed gas supply chamber 7 is provided, and a mixed gas passage hole 9 is formed at the center of the partition wall 8, and the mixed gas from the mixed gas passage hole 9 is supplied to the base end side. A cylindrical body 10 that is guided and ejected toward the existence side of the combustion chamber Ne is provided in a posture protruding from the partition wall 8 toward the existence side of the base end side combustion chamber Ne.
Accordingly, the proximal-side ejection part F is configured to guide the mixed gas supplied from the mixed gas supply part K to the cylindrical body 10 through the mixed gas passage hole 9 and eject the mixed gas from the cylindrical body 10. .

  A flame-holding hole 11 for forming a flame-holding is formed at a position on the outer peripheral side of the central portion of the partition wall 8, and the proximal-side ejection portion is formed by the combustion flame formed in the flame-holding hole 11. The combustion flame formed by the mixed gas ejected from F is configured to hold the flame.

Incidentally, in this embodiment, the mixed gas supply chamber 7 is configured using a tube having a nominal diameter of 25A.
Therefore, as described above, the inner pipe 2 is configured using a pipe having a nominal diameter of 25A, and the proximal combustion chamber Ne is configured using a pipe having a nominal diameter of 32A. In the embodiment, the mixed gas supply chamber 7 and the inner pipe 2 have the same diameter, and the proximal-side combustion chamber Ne is formed larger in diameter than the mixed gas supply chamber 7 and the inner pipe 2.

(Configuration of mixed gas supply unit)
As shown in FIG. 1, the mixed gas supply unit K includes a blower 12 that blows the combustion air A, and a mixing unit 13 that mixes the combustion air A and the gas fuel G from the blower 12. The mixed gas mixed in the section 13 is configured to be supplied to the mixed gas supply chamber 7.
In addition, since the mixing part 13 is comprised using a venturi-type mixer etc. and the structure is known, detailed description is abbreviate | omitted in this embodiment.

  The air passage 14 that supplies the combustion air A from the blower 12 to the mixing unit 13 is provided with an air amount adjusting damper 15 that adjusts the supply amount of the combustion air A supplied to the mixing unit 13. A gas fuel path 17 that supplies the fuel G to the mixing unit 13 is provided with a gas valve 18 that adjusts the supply amount of the gas fuel G supplied to the mixing unit 13 and intermittently supplies the fuel.

Therefore, the mixed gas supply unit K is configured to switch between the base-end combustion supply state and the front-end combustion supply state as described above by adjusting the air amount adjusting damper 15 and the gas valve 18.
Incidentally, in the present embodiment, in the base end combustion supply state, 1 m ³ / H of gas fuel G is supplied, and combustion air A is supplied so that the air ratio is about 1.1. Further, in the state of supply for combustion on the front end side, 2 m ³ / H of gas fuel G is supplied, and combustion air A is supplied so that the air ratio is about 1.1. ing.

The supply amount of the gaseous fuel G to be supplied in the proximal end combustion supply state and the distal end combustion supply state can be variously changed. For example, in the distal end combustion supply state, 2 m ³ / H gas is supplied. Even when the fuel G is supplied, the fuel gas G may be supplied in an amount of less than 1 m ³ / H in the base-side combustion supply state.
The air ratio is not limited to 1.1, and can be variously changed within a range of 1.01 to 1.3, for example.

(Combustion control configuration)
As shown in FIG. 1, a control device H as combustion control means and an operation command unit 19 that commands the control device H for a combustion start command and a combustion stop command are provided.

  That is, when the combustion start command is commanded, the control device H operates the heater drive circuit 5A to start the heating operation of the electric heater 5, and then, based on the detected temperature information of the base end side temperature sensor P, When it is determined that the internal temperature of the base end side combustion chamber Ne is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G, the mixed gas supply unit K is supplied and operated in the base end side combustion supply state. A pre-combustion process is performed.

  When the control device H determines that the internal temperature of the front end side combustion chamber Ns is equal to or higher than the set combustion start temperature based on the temperature information detected by the front end side temperature sensor Q after the preliminary combustion process is executed. The main combustion process for supplying and operating the mixed gas supply unit K in the supply state for the tip side combustion is performed.

More specifically, when the combustion start command is instructed, the control device H stops the electric heater 5 in a state where the supply of the mixed gas from the mixed gas supply unit K is stopped as shown in FIG. The heating operation of the electric heater 5 is continued until the internal temperature of the proximal combustion chamber Ne becomes equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G. become.
In the present embodiment, the set combustion start temperature is set to 760 ° C. or higher in accordance with the description of “Safety technical index of industrial gas combustion equipment: Japan Gas Association January 2009”.

When determining that the internal temperature of the base end side combustion chamber Ne is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G based on the detected temperature information of the base end side temperature sensor P, the control device H The mixed gas supply unit K is supplied and operated in the base end combustion supply state, and the heating operation of the electric heater 5 is stopped.
When the mixed gas supply unit K starts supply operation in the supply state for the base end side combustion, as shown in FIG. 3B, the base end side jetting part F jets the mixed gas into the base end side combustion chamber Ne. As a result, a combustion flame is formed in the proximal combustion chamber Ne.

  Incidentally, at the time of reignition such as when reigniting after temporarily suspending combustion for controlling the furnace temperature, the control device H immediately starts the heating operation of the electric heater 5 and the base end side combustion chamber. When the internal temperature of Ne becomes equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G, the mixed gas supply unit K is supplied and operated in the supply state for the proximal end combustion.

In a state where the combustion flame is formed in the proximal end side combustion chamber Ne, the internal temperature of the proximal end side combustion chamber Ne is maintained at the set combustion start temperature or higher by the heat generated by the combustion flame, And the combustion gas from the base end side combustion chamber Ne flows through the inside of the inner pipe 2 to the front end side combustion chamber Ns, and raises the internal temperature of the front end side combustion chamber Ns.
Further, the combustion gas that has flowed to the front end side combustion chamber Ns flows through the exhaust gas passage R and is discharged from the exhaust gas outlet 4 to the outside.

  Incidentally, since the heat storage ceramic layer 3 is provided on the inner surface side of the distal end portion of the outer tube 1, the heat inside the distal combustion chamber Ns is radiated to the outside through the distal end portion of the outer tube 1. As a result, the temperature inside the tip side combustion chamber Ns can be easily raised quickly.

After the control device H supplies and operates the mixed gas supply unit K in the supply state for the proximal combustion, the internal temperature of the distal combustion chamber Ns is determined based on the temperature information detected by the distal temperature sensor Q. If it is determined that the temperature is equal to or higher than the set combustion start temperature higher than the ignition temperature, the mixed gas supply unit K is supplied and operated in the leading-end combustion supply state.
When the mixed gas supply unit K is changed from the proximal combustion supply state to the distal combustion supply state, the combustion flame in the proximal combustion chamber Ne is lifted to the distal combustion chamber Ns, and FIG. As shown, a combustion flame is formed in the front end side combustion chamber Ns.

In the state where the combustion flame is formed in the front end side combustion chamber Ns, the internal temperature of the front end side combustion chamber Ns is maintained at the set combustion start temperature or higher by the heat generated by the combustion flame, and from the front end side combustion chamber Ns. After the exhaust gas flows in the exhaust gas passage R and heats the outer tube 1, the combustion gas is discharged to the outside from the exhaust gas outlet 4, and the outer tube 1 heated by the combustion gas is heated in the furnace space by radiant heat. Will be heated.
Incidentally, the combustion gas flowing in the exhaust gas passage R exerts an action of preheating the mixed gas flowing in the inner pipe 2 toward the tip side combustion chamber Ns.

  Since the heat storage ceramic layer 3 is provided on the inner surface side of the distal end portion of the outer tube 1, the heat inside the distal combustion chamber Ns is radiated to the outside through the distal end portion of the outer tube 1. Therefore, the internal temperature of the tip side combustion chamber Ns is accurately maintained at a temperature equal to or higher than the set combustion start temperature.

  As described above, the single-ended radiant tube burner TB according to the present embodiment sequentially executes the preliminary combustion process and the main combustion process when the combustion start command is instructed. When the mixed gas is jetted into the end side combustion chamber Ne, the internal temperature of the base end side combustion chamber Ne is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G. When the mixed gas is ejected into the chamber Ns, the internal temperature of the front end side combustion chamber Ns is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G, so that the base end side combustion chamber Ne and the front end side combustion chamber Ns When the mixed gas is jetted and burned, the igniter and the ignition sensor become unnecessary.

  Further, since the gas fuel G does not remain in the proximal combustion chamber Ne or the distal combustion chamber Ns whose internal temperature is equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G, the furnace temperature The pre-purge can be omitted at the time of re-ignition such as when the ignition is re-ignited after temporarily suspending the combustion for the above control.

  In addition, the proximal combustion chamber Ne burns a small amount of mixed gas in order to heat the internal temperature of the distal combustion chamber Ns to a set combustion start temperature or higher, and the distal combustion that burns a large amount of the mixed gas. Since the volume is smaller than the volume of the chamber Ns, the amount of heat generated by the electric heater 5 required for heating the internal temperature of the proximal combustion chamber Ne to the set combustion start temperature or higher is small. The power consumption of the electric heater 5 is reduced, and the running cost can be reduced.

  Further, since the combustion gas does not flow in the outer peripheral portion of the base end side combustion chamber Ne, the electric heater 5 provided in the outer peripheral portion of the base end side combustion chamber Ne can be prevented from being heated and burned by the combustion gas. The durability of the electric heater 5 can be improved.

  Further, in the state where the mixed gas is supplied in the base end side combustion supply state and the combustion flame is formed in the base end side combustion chamber Ne, the base end side combustion chamber is changed to the front end side combustion supply state. Since the combustion flame formed in Ne is lifted to the front end side combustion chamber Ns, the combustion flame is formed in the front end side combustion chamber Ns from the state in which the combustion flame is formed in the base end side combustion chamber Ne and burns. Since the transition to the combustion state is performed while the flame formation state is continued, the base side combustion is performed while suppressing inconveniences such as the occurrence of unburned gas fuel G in the mixed gas as much as possible. It is possible to satisfactorily shift from a state in which the combustion flame is formed in the chamber Ne to burn to a state in which the combustion flame is formed in the front side combustion chamber Ns and burned.

  Incidentally, in the above-described embodiment, when the control device H starts combustion, first, the heating operation of the electric heater 5 is started in a state where supply of the mixed gas from the mixed gas supply unit K is stopped. Thereafter, when the internal temperature of the base end side combustion chamber Ne becomes equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel, a preliminary combustion process for supplying and operating the mixed gas supply unit K in the base end side combustion supply state is performed. After the start of the preliminary combustion process, when the internal temperature of the front combustion chamber Ns becomes equal to or higher than the set combustion start temperature, the main combustion process for supplying and operating the mixed gas supply unit K in the front combustion supply state The combustion method of the single end type radiant tube burner which performs is performed.

[Another embodiment]
Next, another embodiment is listed.
(1) In the above-described embodiment, the case where the outer tube 1 and the inner tube 2 are formed of a metal material is exemplified, but the outer tube 1 and the inner tube 2 may be formed of a ceramic having heat storage properties. Good.
In this case, the entire tip side portion of the outer tube 1 functions as the heat storage ceramic layer 3.

(2) In the above embodiment, the electric heater 5 is exemplified as the electric heating means. However, as the electric heating means, for example, the wall portion of the proximal combustion chamber Ne is formed of a magnetic material, Various modifications can be made to the specific configuration of the electric heating means, such as using an electromagnetic induction heating device for induction heating the wall portion.

(3) In the above embodiment, the mixed gas supply chamber 7 and the inner tube 2 are formed to have the same diameter, and the proximal-side combustion chamber Ne is formed to have a larger diameter than the mixed gas supply chamber 7 and the inner tube 2. However, the size of each part can be variously changed as long as the combustibility can be ensured, for example, the base end side combustion chamber Ne, the mixed gas supply chamber 7 and the inner pipe 2 all have the same diameter.

(4) In the above-described embodiment, in the supply state for the front end side combustion, the mixed gas is ejected from the base end side ejection portion F to the base end side combustion chamber Ne, and in the supply state for the base end side combustion. When the mixed gas is supplied and the combustion flame is formed in the proximal combustion chamber Ne, the combustion flame formed in the proximal combustion chamber Ne is changed to the distal combustion chamber Ne by changing to the distal combustion supply state. The case of lifting to the side combustion chamber Ns has been exemplified. For example, in the supply state for the front end side combustion, the base end side combustion chamber is not supplied from the base end side ejection portion F to the base end side combustion chamber Ne. The mixed gas may be directly supplied to Ne. In this case, the gas fuel G in the mixed gas injected into the front end side combustion chamber Ns is ignited (reignition) inside the front end side combustion chamber Ns. Will do.

(5) In the above embodiment, in the state where the mixed gas is supplied in the supply state for the proximal end side combustion and the combustion flame is formed in the proximal end side combustion chamber Ne, the state is changed to the supply state for the distal end side combustion. In the above example, when the combustion flame formed in the proximal combustion chamber Ne is lifted to the distal combustion chamber Ns, the air ratio of the mixed gas is maintained at the same ratio, but the proximal combustion chamber Ne is illustrated. When the combustion flame formed on the tip side combustion chamber Ns is lifted to the tip side combustion chamber Ns, the air ratio in the tip side combustion supply state is set lower than that in the base side combustion supply state, and the combustion flame is easily lifted. It may be.

  It should be noted that after the combustion flame formed in the proximal combustion chamber Ne is lifted to the distal combustion chamber Ns, it is preferable to return the air ratio to the original value. However, when the gas fuel G can be combusted properly, the state in which the air ratio is lowered may be maintained.

(6) In the above embodiment, the control device H as the combustion control means determines that the internal temperature of the base end side combustion chamber Ne is higher than the ignition temperature of the gas fuel G based on the detected temperature information of the base end side temperature sensor P. Is determined to be higher than the set combustion start temperature, and based on the detected temperature information of the tip side temperature sensor Q, the internal temperature of the tip side combustion chamber Ns is higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G. However, the proximal end temperature sensor P and the distal end temperature sensor Q may be omitted.

That is, for example, when the control device H as the combustion control means starts the heating operation of the electric heater 5 as the electric heating means, and the elapsed time reaches the base end side set time, the base end side combustion chamber Ne. Is determined to be equal to or higher than the set combustion start temperature higher than the ignition temperature of the gas fuel G, and when the elapsed time from the start of the supply state for the base end combustion reaches the tip set time, You may implement in the form discriminate | determined that the internal temperature of the combustion chamber Ns is more than the preset combustion start temperature higher than the ignition temperature of the gas fuel G. FIG.
Note that the proximal side set time and the distal side set time are obtained and set in advance through experiments.

(7) In the above embodiment, the set combustion start temperature is set to 760 ° C. in accordance with the contents described in “Industrial Gas Combustion Equipment Safety Technology Index: Japan Gas Association January 2009”. Although illustrated, the set combustion start temperature can be set to a temperature higher or lower than 760 ° C. The point is that the set temperature may be set to a temperature at which the gas fuel G can be burned accurately.

DESCRIPTION OF SYMBOLS 1 Outer pipe 2 Inner pipe 3 Ceramic layer 5 Electric heating means 6 Heat insulation layer A Combustion air F Base end side ejection part G Gas fuel H Combustion control means K Mixed gas supply part Ne Base end side combustion chamber Ns Front end side combustion chamber R exhaust gas passage

Claims (5)

Inside the outer tube whose front end is blocked, an inner tube with both ends opened is provided.
A single-ended radiant tube burner in which an exhaust gas passage is formed between the outer tube and the inner tube to allow combustion gas to flow from the distal end side to the proximal end side of the outer tube;
A base end side combustion chamber communicating with the base end portion of the inner pipe is provided;
Between the distal end portion of the outer tube and the distal end portion of the inner tube, a distal end side combustion chamber having a larger volume than the proximal end side combustion chamber is formed,
A base end jetting part is provided for injecting a mixed gas of gas fuel and combustion air into the base end side combustion chamber to form a combustion flame in the base end side combustion chamber;
A mixed gas supply unit that supplies a mixed gas of gas fuel and combustion air injects the mixed gas into the base end side combustion chamber by the base end side jet unit to form a combustion flame in the base end side combustion chamber A base-end combustion supply state, and a larger amount of mixed gas than the base-end combustion supply state is caused to flow into the inner pipe through the base-end combustion chamber in a non-combustion state. It is configured to be switchable to a front-end combustion supply state that is jetted from the front end of the inner pipe to the front-end combustion chamber and forms a combustion flame in the front-end combustion chamber,
Electric heating means for heating the base end side combustion chamber is provided on the outer periphery of the base end side combustion chamber,
Combustion control means
When a combustion start command is issued, the heating operation of the electric heating means is started in a state where the supply of the mixed gas from the mixed gas supply unit is stopped, and then the internal temperature of the proximal combustion chamber is A pre-combustion process for supplying and operating the mixed gas supply unit in the base-side combustion supply state when the set combustion start temperature is higher than the ignition temperature of the gas fuel; and
After starting execution of the preliminary combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature, the main combustion process for supplying and operating the mixed gas supply unit in the front end side combustion supply state Single-ended radiant tube burner that is configured to perform. The mixed gas supply unit is configured to inject the mixed gas from the base end side injection portion to the base end side combustion chamber in the supply state for the front end side combustion,
The relationship between the proximal end combustion supply state and the distal end combustion supply state is that the mixed gas is supplied in the proximal end combustion supply state, and a combustion flame is formed in the proximal end combustion chamber. 2. The single-ended type according to claim 1, wherein, when the state is changed to the front-end combustion supply state, the combustion flame formed in the base-end combustion chamber is lifted to the front-end combustion chamber. Radiant tube burner.   The single-ended radiant tube burner according to claim 1 or 2, wherein a ceramic layer for heat storage is provided on at least the inner surface side of the tip side portion of the outer tube. The electric heating means is an electric heater disposed in an outer peripheral portion of the proximal combustion chamber;
The single-ended radiant tube burner according to any one of claims 1 to 3, wherein a heat insulating layer is provided so as to cover an outer peripheral portion of the electric heater. Inside the outer tube whose front end is blocked, an inner tube with both ends opened is provided.
A combustion method for a single-ended radiant tube burner, in which an exhaust gas passage is formed between the outer tube and the inner tube to allow combustion gas to flow from the distal end side to the proximal end side of the outer tube,
A base end side combustion chamber communicating with the base end portion of the inner pipe is provided;
Between the distal end portion of the outer tube and the distal end portion of the inner tube, a distal end side combustion chamber having a larger volume than the proximal end side combustion chamber is formed,
A base end jetting part is provided for injecting a mixed gas of gas fuel and combustion air into the base end side combustion chamber to form a combustion flame in the base end side combustion chamber;
A mixed gas supply unit that supplies a mixed gas of gas fuel and combustion air injects the mixed gas into the base end side combustion chamber by the base end side jet unit to form a combustion flame in the base end side combustion chamber A base-end combustion supply state, and a larger amount of mixed gas than the base-end combustion supply state is caused to flow into the inner pipe through the base-end combustion chamber in a non-combustion state. It is configured to be switchable to a front-end combustion supply state that is ejected from the front end of the inner pipe to the front-end combustion chamber and forms a combustion flame in the front-end combustion chamber
Electric heating means for heating the base end side combustion chamber is provided on the outer periphery of the base end side combustion chamber,
When starting the combustion, first, the heating operation of the electric heating means is started in a state where the supply of the mixed gas from the mixed gas supply unit is stopped, and then the internal temperature of the base end side combustion chamber is started. Is a set combustion start temperature higher than the ignition temperature of the gas fuel, perform a pre-combustion process to supply the mixed gas supply unit in the base-side combustion supply state,
After starting execution of the preliminary combustion process, when the internal temperature of the front end side combustion chamber becomes equal to or higher than the set combustion start temperature, the main combustion process for supplying and operating the mixed gas supply unit in the front end side combustion supply state Perform a single-ended radiant tube burner combustion method.

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