JPH06272859A - Device and method for confirming ignition state of combustion furnace - Google Patents

Abstract

PURPOSE:To quickly confirm an ignition state upon starting a combustion furnace by deflecting a pressure change in the course of a supply passage of fuel gas or oxidizing agent gas to the combustion furnace. CONSTITUTION:A control valve 7 for oxidizing agent gas is opened to introduce the oxidizing gas into a combustion chamber 5, and a fine pressure difference sensor 12 confirms that fuel gas is ignited and combustion is continued. Pressure is instantaneously raised owing to small explosion in the combustion chamber 5 at the instant of the ignition. Fire pressure waves produced at that time is transmitted to a pressure detection side of the fine pressure difference sensor 12 through an oxidizing agent gas flow passage 8, and conduits 11, 13, and on the back pressure side of the fine pressure difference sensor 12 the instantaneous rise of the pressure is attenuated because of the existance of the throttle valve 16 in the course of a chamber 14 and a conduit 15, so that the firing is confirmed by the detection of the pressure difference by the fine pressure difference sensor 12. Hereby, ignition conditions upon starting of the combustion furnace are rapidly confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for confirming an ignition state at the time of starting a combustion furnace and a confirmation method thereof.

[0002]

2. Description of the Related Art In recent years, combustion furnaces have been changed from solid fuels to liquid or gas fuels, which has led to frequent occurrence of explosion accidents due to poor ignition or misfire of the fuel. For this reason, an automatic device is installed to detect a change in the ignition state in the combustion furnace at an early stage and appropriately perform a safety measure operation such as stopping the fuel in the combustion furnace. As a result of various studies, the method of detecting ignition failure and misfire in a combustion furnace is currently effective because an optical method is more effective for early detection than a method of detecting temperature. Flame monitoring devices that capture electromagnetic waves such as visible light and visible light are most widely used.

[0003] In order to use a large amount of hydrogen as a future clean fuel and methanol as an inexpensive fuel that is low in pollution and easy to transport, it is required to develop a large-scale device.
The biggest problem in the development of large-scale hydrogen and methanol production equipment is a gas reformer for producing synthesis gas from hydrocarbons. Recently, a method that combines partial oxidation with partial oxidation has been receiving attention. In this method, the primary reforming reaction is carried out by the contact reaction between hydrocarbons and steam, the oxidizing gas is added to carry out partial oxidation, then the secondary reforming reaction is carried out, and the obtained high-temperature gas is used as the heat source for the primary reforming reaction. Is used for. This is because it does not need to supply heat from other sources and therefore does not need to use a reforming furnace that externally heats the primary reforming reaction tube, so that the gas reforming apparatus can be operated at a high pressure and can be easily enlarged. There are advantages. In this way, the autothermal exchange type reactor (hereinafter, referred to as the primary reforming reaction, the partial oxidation and the secondary reforming reaction)
This is referred to as "adiabatic reformer"), as disclosed in JP-A-60-186401, JP-A1-261201 and JP-A-2-830.
The concrete structure is shown in No. 3 etc.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention A flame monitoring device for capturing electromagnetic waves such as infrared rays, ultraviolet rays, and visible rays emitted by a flame is capable of accurately detecting the presence or absence of a flame by installing a detection end at an appropriate position, and responding thereto. Since it is fast, it is widely used in general combustion furnaces. However, since the optical sensor (photocell) used for this is covered with transparent glass, it cannot be used under high pressure,
Generally designed to withstand a pressure of about 10 atmospheres. Even a specially designed sensor has a limit of 20-30 atm, and this specially designed sensor is quite expensive.

The inventors have developed a large-scale hydrogen production apparatus using an adiabatic reformer and are studying a process in which the gas reformer is operated at a pressure of 80 atm or higher. In this process, the primary reformed gas is used. In order to safely start the process of partial oxidation of methane, it is necessary to confirm the ignition state when the oxidant gas is introduced.

However, the commonly used electromagnetic wave flame monitoring device cannot be used for the above reason. The inventors have considered monitoring with a temperature sensor as an alternative, but the combustion chamber of the adiabatic reformer
Since the internal temperature of the (furnace) is 1500 ° C or higher, there is no temperature sensor for the material that withstands this temperature.Therefore, it was tried to put the temperature sensor in a protective tube using a heat resistant material such as ceramics for detection. Detection through a thick protective tube wall was dangerous because it caused a time delay.

In general, the ignition of a combustion furnace is performed by generating an electric spark while introducing a small amount of fuel gas and oxidant gas, but the internal temperature of the combustion chamber (furnace) becomes 1500 ° C. or higher as described above. In some cases it is difficult to install an electric spark. For this reason, there is no choice but to adopt a method in which the fuel gas is heated to a temperature higher than the ignition point and a small amount of oxidant gas is introduced to ignite, but the ignition is not confirmed and the combustible gas and oxidant gas are introduced. If you continue to, there is a danger of explosion in the furnace, and the damage will be extremely large, so you must absolutely avoid it. It is an object of the present invention to provide a method and an apparatus thereof, in particular, for completely confirming the ignition state in such a high pressure combustion furnace and continuing safe operation of the combustion furnace.

[0008]

Means for Solving the Problems The inventors of the present invention have made earnest studies on a method for confirming the ignition state of a combustion furnace having the above-mentioned problems, and particularly for confirming the ignition state of an adiabatic reformer that burns under high pressure. The inventors have found that the ignition state of the combustion furnace can be promptly confirmed by detecting a change in the pressure in the supply passage of the fuel gas or the oxidant gas, and have reached the present invention.

That is, according to the present invention, a conduit for pressure detection is installed in the middle of a fuel gas or oxidant gas supply passage of a combustion furnace, and the conduit is branched into two to receive the pressure of a diaphragm type differential pressure sensor. A method for confirming an ignition state and an apparatus therefor, characterized by being connected to a back pressure portion of the sensor via a section and a chamber and detecting a pressure difference variation between the pressure receiving section and the back pressure section.

Although the method and apparatus of the present invention are employed in general low pressure combustion furnaces, they are advantageously used in combustion furnaces in which combustion is performed under a high pressure of 10 atm or more, particularly 30 atm or more. Examples of the use of such a high-pressure combustion furnace include a gas reformer by partial oxidation of hydrocarbons,
A gas reformer that performs a primary reforming reaction by contacting hydrocarbons and steam, then mixes air or oxygen in the combustion chamber (furnace) to perform partial oxidation, and then performs a secondary reforming reaction, and A primary reforming reaction is carried out by the catalytic reaction of hydrocarbons and steam, and after partial oxidation by adding an oxidant gas, a secondary reforming reaction is carried out, and the obtained high temperature gas is used as a heat source for the primary reforming reaction. Quality equipment (adiabatic reformer). The reformed gas thus obtained is used for producing hydrogen and carbon monoxide, or for producing synthetic gas for synthesizing methanol, ammonia and organic chemicals.

The combustion furnace in the present invention is a device in which a fuel gas and an oxidant gas are mixed to carry out an oxidation reaction,
Also included is the combustion chamber of the reactor, such as the adiabatic reformer described above. Therefore, in the combustion furnace of the present invention, other than a general combustion furnace for heating various substances, generating steam or heating,
As described above, there are reactors and the like used when partial oxidation of hydrocarbons is carried out for the production of hydrogen and carbon monoxide and the production of synthesis gas such as methanol and ammonia.

Examples of the fuel gas used in the combustion furnace include gaseous fuels such as natural gas and LPG, but also steam reformed gas in which partial oxidation is carried out, ammonia, methanol and organic chemical substances. Purge gas discharged from the synthesizer or the like, or a mixture of these gases is also included. Examples of the oxidant gas include oxygen gas, air and oxygen-enriched air. These fuel gas and oxidant gas are often heated and supplied to the combustion furnace in order to appropriately maintain the combustion state in the combustion furnace,
Further, steam may be mixed with the fuel gas or the oxidant gas in order to prevent carbon deposition in the case of performing partial oxidation.

At the moment when the fuel gas comes into contact with the oxidant gas and ignites, a small explosive combustion always occurs although there is a difference in size, and it is generally confirmed by sound or light. At this time, if a person cannot perceive it, a minute change in atmospheric pressure occurs in the surrounding gas phase, and if combustion continues steadily thereafter,
A distinctive minute pressure fluctuation due to combustion is clearly seen, which is clearly different from that before the start of combustion. In the present invention, the state where the ignition and the combustion are continued is referred to as the "ignition state". If this minute change in pressure can be captured, the state of ignition can be confirmed instantly. The present invention detects this minute pressure change by installing a conduit in the middle of the fuel gas or oxidant gas supply flow path and attaching a diaphragm type differential pressure sensor.

A pipe having an inner diameter of about 3 to 10 mm is generally used as a conduit from the fuel gas or oxidant gas supply flow path to the minute differential pressure sensor, and is connected to the pressure receiving side of a diaphragm type differential pressure transmitter. A container (chamber) for absorbing pressure fluctuation is installed on the back pressure side of the diaphragm type differential pressure transmitter, and is connected to the original fuel gas or oxidant gas supply passage through a conduit. A restrictive orifice or throttle valve is installed to regulate the flow rate in this conduit. However, the inside diameter of this conduit is 0.2-1 mm
It is also possible to eliminate such a restriction orifice and a throttle valve by using a pipe of a certain degree.

A diaphragm type differential pressure transmitter is used as a minute differential pressure sensor for detecting a minute pressure change. This fine differential pressure sensor preferably has a pressure measuring span of 3000 mm or less in water column pressure, and preferably 500 mm or less in water column pressure. The information detected by the slight differential pressure sensor can be recorded in a recorder to catch the ignition state, and it is preferable to connect the alarm.

A suitable distance is selected for the position where the conduit for the slight differential pressure sensor is attached to the fuel gas or oxidant gas supply passage because the detection sensitivity becomes low if the distance to the combustion burner is large. The ignition time is the distance from the fuel gas or oxidant gas supply valve to the combustion burner, the pipe diameter of the flow passage,
It can be calculated in advance from the gas flow rate, pressure, and temperature, and the ignition state is surely confirmed by comparing the calculated value of this time with the time when the pressure by the differential pressure sensor fluctuates.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments of the present invention using the drawings. FIG. 1 is a system diagram when the ignition confirmation device of the present invention is installed in an adiabatic reformer. Figure 1
The reactor described in JP-A-60-186401 is an adiabatic reformer. A primary reforming reaction tube 2 is installed inside the outer grain 1, and a mixed gas of raw material hydrocarbons and steam is passed through the flow path 3
The primary reforming reaction is carried out by coming into contact with the catalyst introduced into the primary reforming reaction tube.

The primary reformed gas is passed through the transportation pipe 4 and the combustion chamber
Introduced in 5. On the other hand, the oxidant gas (oxygen) is introduced into the combustion chamber from the flow path 6 through the flow rate control valve 7 and the flow path 8 to partially oxidize the primary reformed gas. The partially oxidized gas comes into contact with the secondary reforming catalyst layer 9 to become the secondary reformed gas, and this high-temperature gas passes outside the primary reforming reaction tube 2 and is used as a heat source for the primary reforming reaction. After that, it is sent to the next step from the flow path 10 to recover heat, and is cooled to condense and separate unreacted water vapor.

The ignition confirmation device of the present invention is installed in the middle of the flow path 8 for introducing the oxidant gas into the combustion chamber 5. Combustion chamber 5
It is desirable to install a conduit 11 for detecting pressure in order to detect a minute change in pressure inside the combustion chamber as close to the combustion chamber as possible, and to minimize valves and bent portions in the middle thereof. This conduit is branched into a conduit 13 connected to the pressure receiving side of the slight differential pressure sensor 12 and a conduit 15 connected to the chamber 14, and a throttle valve 16 is installed in the middle of this conduit 15.
The back pressure side of the slight differential pressure sensor 12 and the chamber are connected by a conduit 17. Information from the differential pressure sensor 12 is
The pressure change can be monitored in the control room by being sent to the recorder 19 and continuously recorded via the transmission circuit 18,
It is also linked to an alarm.

When activating the adiabatic reformer of FIG.
First, the mixed gas of combustible gas and water vapor is heated to a temperature higher than the ignition temperature and supplied from the flow path 3, the inside of the adiabatic reformer reactor is sufficiently heated, and the inside of the combustion chamber 5 is heated to a temperature higher than the ignition temperature. Confirm that it has become. Next, the oxidant gas control valve 7 (or the sluice valve) is opened to introduce the oxidant gas into the combustion chamber, and it is confirmed by the slight differential pressure sensor that the fuel gas is ignited and the combustion is continued. Combustion chamber at the moment of ignition
The pressure rises momentarily due to a small explosion in the (furnace). The minute pressure wave generated at this time is the oxidant gas flow path 8 and the conduit 11
Is transmitted to the pressure receiving side of the slight differential pressure sensor 12 via the conduit 13 and the back pressure side of the slight differential pressure sensor 12, and the chamber 14 and the conduit 15
Since there is a throttle valve 16 in the middle of, a momentary increase in pressure is attenuated and erased, so ignition is confirmed from the detection of the differential pressure by the slight differential pressure sensor.

As described above, the moment of ignition is confirmed by the instantaneous increase in the differential pressure between the pressure receiving side and the back pressure side of the slight differential pressure sensor. Although there is no particular restriction on the operating pressure at the time of ignition, it is preferable to set the pressure in the reactor or the combustion chamber (furnace) to be lower than the normal operating pressure at the time of start-up for safety reasons. The time required for the oxidant gas to reach the combustion chamber through the flow path 8 is
It is calculated by the distance to the combustion chamber and the amount of oxidizing gas, temperature, and pressure, but it is necessary to design the distance to the combustion chamber so that the time is several seconds to several tens of seconds. This time is calculated in advance, and if the ignition state is not confirmed within substantially that time, the supply of the oxidant gas and the flammable gas is stopped, and an inert gas is introduced into the reactor, The inside of the reactor is completely replaced with an inert gas, and the above heating degree operation is repeated.

After confirming the ignition state in the combustion chamber (furnace), the supply amount of the mixed gas of combustible gas (hydrocarbon) and steam and the supply amount of the oxidant gas from the flow path 3 are checked. Increase the pressure in the reactor and shift to normal operation. Although the case where the adiabatic reformer of FIG. 1 is started has been described above, the same operation is performed when the ignition confirmation device of the present invention is installed in another hydrocarbon reactor having partial oxidation or a general combustion furnace. Is done.

[0023]

EXAMPLE Adiabatic reformer reactor shown in FIG. 1 (operating pressure
At 80 kg / cm ² G, combustion chamber diameter 0.7 m, the system was replaced with nitrogen gas, and then a mixture of combustible gas and steam (CO 0.8 mol%, CO ₂ 3.9 mol%, CH ₄ 9.1 mol%, H
₂ 24.8mol%, N ₂ 4.0mol%, H ₂ O 57.4mol%) 35kgmol / h
r was introduced at 630 ° C and the pressure was maintained at 17.9 kg / cm ² G. The flow path 8 from the oxidant gas control valve 7 to the combustion chamber has a distance of 16.2 m and an inner diameter of 16.2 mm. This pipe was also replaced with nitrogen gas at the same pressure. After it was confirmed that the temperature of the secondary reforming catalyst layer 9 reached 615 ° C and reached the ignition temperature or higher, the control valve 7 was opened and pure oxygen gas was added to 7.5
It was introduced into the reactor at Nm ³ / hr.

The fluctuation of the differential pressure of the slight differential pressure sensor at this time is shown in FIG. According to this, a small pressure peak at the moment when the control valve 7 is opened, a second pressure peak after 24 seconds and a characteristic pressure fluctuation due to the subsequent combustion are confirmed, and the temperature of the secondary reforming catalyst layer 9 is then 615 ° C. Rose more gradually. Channel 8
Based on the distance and inner diameter, the amount of pure oxygen gas introduced, and the pressure and temperature conditions, the time for pure oxygen gas to reach the combustion chamber from the control valve 7 is approximately 21 seconds. It is judged that the ignition was performed in combustion chamber 5 at. After that, the gas supplied from the flow path 3 was a mixed gas of natural gas and water vapor, and the amount was gradually increased along with pure oxygen gas to raise the pressure, and the operation was shifted to normal operation at a pressure of 80 kg / cm ² G.

[0025]

According to the method of the present invention, the ignition status at the time of starting the combustion furnace can be confirmed quickly, so that the combustion furnace can be safely started. Further, the ignition confirmation device of the present invention increases the differential pressure sensitivity of the differential pressure sensor even during normal operation, and by continuing to monitor the minute fluctuations during normal operation, for example, damage or misfire of the pure oxygen burner. It is also possible to check the included combustion abnormality. The method of the present invention can be applied to a combustion chamber (furnace) in a reactor or the like in which combustion is performed at high pressure, and is a very advantageous method in terms of cost.

[0026]

[Brief description of drawings]

FIG. 1 shows a system diagram when an ignition confirmation device of the present invention is installed in an adiabatic reformer.

FIG. 2 shows fluctuations in the differential pressure of the slight differential pressure sensor in the example.

[0027]

[Explanation of symbols]

 1 Outer grain of adiabatic reformer 2 Primary reforming reaction tube 3 Flow path for mixed gas of raw hydrocarbon and steam 4 Primary reformed gas transport tube 5 Combustion chamber 6 Flow path for oxidant gas (oxygen) 7 Flow control valve 9 2 Secondary reforming catalyst layer 10 Secondary reformed gas outlet flow path 11 Pressure detection conduit 12 Fine differential pressure sensor 14 Chamber 16 Throttle valve 19 Recorder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Hasegawa 2-53-1, Shirute, Tsurumi-ku, Yokohama-shi, Kanagawa Japan Furnace Industry Co., Ltd.

Claims (5)

[Claims] 1. A conduit for pressure detection is provided in the middle of a fuel gas or oxidant gas supply passage, and the conduit branches into two via a pressure receiving portion and a chamber of a diaphragm type differential pressure sensor. For confirming the ignition state of the combustion furnace connected to the back pressure part of the sensor 2. A device for confirming an ignition state of a combustion furnace according to claim 1, wherein a restricting orifice or a throttle valve is provided between the branched conduit and the chamber. 3. A pressure detecting conduit is installed in the middle of a fuel gas or oxidant gas supply passage of a combustion furnace, and the conduit is branched into two to form a pressure receiving portion and a chamber of a diaphragm type differential pressure sensor. A method for confirming an ignition state, characterized in that it is connected to a back pressure portion of the sensor via a sensor to detect a pressure difference variation between the pressure receiving portion and the back pressure portion. 4. In a gas reforming production apparatus having partial oxidation of hydrocarbons or partial oxidation of steam reformed gas of hydrocarbons, an oxidant gas or hydrocarbon supply flow path of a oxidant gas to a combustion furnace for performing partial oxidation reaction is provided. The ignition state confirmation method according to claim 3, wherein a conduit for pressure detection is installed on the way. 5. A primary reforming reaction is carried out by a catalytic reaction of hydrocarbon and steam, and after partial oxidation by adding an oxidant gas, a secondary reforming reaction is carried out, and the obtained high temperature gas is subjected to primary reforming reaction. A method for confirming an ignition state according to claim 3, wherein in a gas reformer used as a heat source, a conduit for pressure detection is installed in the middle of a supply flow path of an oxidant gas or a hydrocarbon to a combustion furnace that performs a partial oxidation reaction.