JPS62108466A - Device for discharging inflammable gas into atmosphere - Google Patents

Abstract

PURPOSE:To improve safety with a simple structure by arranging a heat absorbing porous board made of heat-resisting and thermally conductive material in a water-sealed drum, thereby discharging the inflammable gas through the heat absorbing member into the atmosphere. CONSTITUTION:Meshes, grids or porous-board type heat-absorbing boards 26 composed of elements made of heat-absorbing boards 26 composed of elements made of heat-resisting and thermally conductive material are arranged in plural stages below the water level in a water-sealed drum 20 for preventing the backfire. An opening 27 that is the gas blow-out port of an underwater open tube 22 is positioned below the heat-absorbing board 26. High temperature inflammable gas from a fuel cell generating plant etc. is passed through a heat- absorbing liquid 2 and discharged into the atmosphere thus forming a device for discharging inflammable gas into the atmosphere. Consequently, the heat is taken out from the inflammable gas through contact heat-exchange, resulting in improvement of safety of discharging the excessive inflammable gas to be produced in a plant etc. upon emergency or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a combustible gas atmospheric discharge device for discharging flammable gas from a fuel cell power generation plant or a chemical plant into the atmosphere.

[Technical background of the invention and its problems] Fuel cells have been known as devices that directly convert chemical energy contained in fuel into electrical energy. This fuel cell usually has a pair of porous snow scrapers sandwiching an electrolyte, and a fuel gas such as hydrogen is brought into contact with the back of one electrode, and an oxidizing gas such as oxygen is brought into contact with the back of the other electrode. The system extracts electrical energy from between the two electrodes by bringing them into contact and utilizing the electrochemical reaction that occurs.As long as the fuel gas and oxidant gas are supplied, electrical energy can be extracted with high conversion efficiency. can be taken out. Among these fuel cells, power generation plants equipped with phosphoric acid fuel cells using phosphoric acid as an electrolyte are being put into practical use.

FIG. 4 shows an example of the system configuration of this type of phosphoric acid fuel cell power generation plant. In the figure, a fuel cell 1 is configured to generate electricity by electrochemically reacting hydrogen, which is a fuel, and oxygen, which is an oxidizing agent.
It is particularly called a phosphoric acid fuel cell because it uses a phosphoric acid aqueous solution as its electrolyte. On the other hand, natural gas is supplied from the raw fuel inlet pipe 2, mixed with steam supplied from the steam inlet pipe 3, and introduced into the reformer 4. The reformer 4 also includes a reforming tube 5 that communicates with the raw fuel inlet pipe 2 and has a reforming catalyst inside, and a combustion chamber 6 that has a burner 7. Burner combustion air and burner combustion fuel gas branched from the air inlet pipe 8 are supplied as agents to generate combustion gas,
This combustion gas heats the reforming tube 5 and then passes through the combustion exhaust gas pipe and is released into the atmosphere from the exhaust stack 9. Although the exhaust gas from the battery fuel electrode is used as the fuel gas for combustion in the above, raw fuel gas may also be used as it is, and low oxygen concentration air from the battery air electrode is also used for burner combustion air. In some cases.

On the other hand, when the raw fuel into which water vapor has been introduced passes through the reforming pipe 5, it undergoes a reforming reaction as shown in the reaction equation below due to the action of the catalyst, and becomes reformed gas with a high hydrogen concentration, which is then passed through the reformed gas pipe. introduced in 10.

CH4+2820-+4H2+CtO2 The reaction in the above equation is endothermic and 600'c1:l.

Since a temperature above 12 is required, burner 7
A combustion gas of 00 to 1400°C is generated and the necessary heat is supplied to the catalyst through the reforming tube 5. However, at the same time, the following reactions also proceed, and carbon monoxide is generated, which may poison the catalyst used in the fuel cell 1.

CO2+H2=CO+H20 Therefore, in order to prevent this, the reformed gas coming out of the reformer 4 is passed through the converter 11, and the carbon monoxide concentration is sufficiently lowered by the conversion reaction shown in the following reaction formula. The fuel is introduced into the fuel cell 1 from the cell fuel pipe 12 as a fuel.

CO+820-+CO2+82 Here, the conversion reaction may be carried out in two stages, high temperature and low temperature, and in that case, two types of converters are installed.

In addition, in the actual plant, various heat exchangers for heat recovery 1m degree control, moisture control of fuel entering the battery, dehumidifier for removing water produced in the battery, etc. will also be installed. However, since it is not directly related to the present invention, illustration and explanation thereof are omitted here.

On the other hand, air as an oxidizer is introduced into the fuel cell 1 from a branch of the air inlet piping 8 or from another air supply source, after being preheated to a temperature suitable for electrochemical reactions within the cell by various heat exchangers (not shown). be done. And this fuel cell 1
The exhaust air that exits the battery.

The air is discharged into the atmosphere from the exhaust pipe through an exhaust pipe 13.

The above is an overview of the basic configuration of a fuel cell power generation plant, but there is also an important component that processes surplus fuel gas generated within the plant during initial test runs, emergencies, and the like. In other words, the fuel gas is
Raw fuel gas such as natural gas, reformed gas piping 10.
It is roughly divided into cell fuel gas (reformed gas) with a high hydrogen concentration flowing through the cell fuel piping 12, and exhaust fuel gas whose concentration has become low due to the consumption of hydrogen in the cell, and both of these are flammable gases. be. For this reason, during initial test runs, a dummy battery is installed in place of fuel cell 1, and fuel equivalent to the amount of hydrogen consumed by fuel cell 1 is discharged outside the system to perform a simulation test of actual operation and make plant adjustments. , this excess fuel gas is discharged by the pack vent valve 14. In addition, each equipment in the plant is equipped with safety valves 15.
16, 17° 18 are provided, and if an abnormal situation occurs in which the internal pressure of the container exceeds the maximum working pressure, these safety valves 15, 16, 17, 18 operate to release gas and prevent the pressure from rising. It looks like this. Furthermore, the differential pressure release valve 19 is used to prevent the differential pressure between the fuel electrode and the air electrode of the fuel cell 1 from becoming excessive and causing crossover, which may cause hydrogen and oxygen to mix and create a dangerous situation. , tlA 14 ti
This is a valve for releasing gas to reduce the differential pressure when the pressure is higher than that of the air electrode, and there is a similar valve on the air electrode side, but it is omitted in FIG. These gases are flammable gases or have the possibility of being mixed with flammable gases, so the exhaust pipe 9
Instead, they are generally treated with a separate release system, which will be discussed below.

Now, in chemical plants with conventional hydrogen production equipment,
Combustible gas is processed using a flare stack. However, fuel cell power plants are often installed near cities, and out of consideration for environmental issues, vent stacks are generally used to release the fuel directly into the atmosphere. Similar considerations are necessary for chemical plants in urban areas, and vent stacks may be used when equipment modification increases the amount of gas released and it is not possible to add or modify flare stacks.

This vent stack system usually consists of a water seal drum 20 and a stack 21, as shown in FIG. In order to prevent backfire when ignited, the flammable gas is fed into the stack 21 through a pipe 22 that is open to water inside the drum. This underwater open pipe 22 may be divided into a plurality of pipes depending on the type of gas. In addition, sealing gas is poured into the stack 21 from the bottom to prevent air from entering inside.
Alternatively, it is common to install a cover with a sealing mechanism on the top, but this is omitted here.

In such a vent stack system, the safety valve 15.16
．． In order to prevent this, there is a possibility of ignition at the exit of the stack 21 in the event of release from a valve installed in a container or piping line containing high-temperature gas (400°C or higher) as shown in No. 17. As shown in the figure, a tray is provided inside the water seal drum 20 and water is rained down from a spray pipe 24, and as shown in FIG. Methods have been devised to cool the emitted gas. However, with the temperature reduction method described above, even if water is injected only in an emergency, due to delays in sensor and valve operation, there is a risk of a fire occurring before cooling is done in time. There is a problem in that it has to be kept flowing.
- [Purpose of the Invention] The present invention has been made to solve the above-mentioned problems, and its purpose is to safely release surplus flammable gas, which occurs in a plant during an emergency, into the atmosphere with a simple structure. An object of the present invention is to provide a device for releasing flammable gas into the atmosphere.

[Summary of the Invention] In order to achieve the above object, the present invention provides a method for discharging flammable gas from a plant into the atmosphere, in which the flammable gas is introduced into the water through a pipe opened into the water. In this method, a plurality of heat absorbers in the form of nets, lattices, or perforated plates made of elements made of heat-resistant and highly conductive materials are placed below the water surface in the water seal drum in a horizontal or inclined state. It is characterized by having a configuration in which it is set.

[Embodiment of the Invention] The present invention will be described in detail below with reference to an embodiment shown in the drawings. FIG. 1 shows an example of the configuration of a combustible gas atmosphere release device according to the present invention. The same parts as in FIGS. I will only talk about.

That is, the flammable gas atmosphere release device according to this embodiment has a net or lattice made of elements made of a material that is heat resistant and has good thermal conductivity under the water surface in the water seal drum 20 to prevent backfire. Or open the perforated heat absorption plate 26 underwater!
! 22, a plurality of them are horizontally arranged above the opening 27 which is the gas outlet.

In the combustible gas atmosphere release device having such a configuration, the high temperature combustible gas released from the fuel cell power generation plant (not shown) passes through the underwater open pipe 22 and exits from the opening 27, and then rises in the water. The water reaches the upper space of the water seal drum 20 and is discharged into the atmosphere via the stack 21. In this case, the rate at which gas rises underwater is largely controlled by the density difference between gas and water, so if a large amount of gas is released and the required flow rate determined from the effective passage area of the gas exceeds the actual rate of rise underwater, Gas blow-through occurs, forming an air column, and the cooling effect of direct contact with water can hardly be expected.

Therefore, in order to maintain a sufficient cooling effect by reducing the required flow rate to below the rising rate, considering the low contact heat transfer between gas and water, the effective passage area must be made considerably large, that is, the diameter of the water seal drum 20. This requires an excessively large space compared to the allowable discharge system space corresponding to the output of the fuel cell power plant. In this point, in the present configuration, even if the drum diameter is small and an air column is generated, the released photocombustible gas will absorb this heat when passing through the heat absorption plate 26 disposed on the gas ascending path in the water seal drum 20. Since the absorption plate 26 absorbs heat through contact heat exchange with the gas, the temperature of the combustible gas is lowered to a level where the possibility of ignition at the exit of the stack 21 is extremely low, and the gas is released into the atmosphere. Therefore, the above-mentioned problems can be eliminated.

As mentioned above, in the flammable gas atmosphere release device of this embodiment, there is no need to worry about time delays, no special control device is required, and the high-temperature combustible gas can be released into the atmosphere with an extremely simple configuration. This makes it possible to do this, and the effect is extremely large.

In addition, in the above, the specific shape and dimensions of the heat absorption plate 26, that is, the diameter of the mesh or lattice element, the mesh or pitch, the hole diameter and pitch of the perforated plate, the number of sheets, etc.
It is determined by the expected amount of flammable gas emissions, temperature and pressure loss tolerances. In other words, in order to increase the cooling effect, it is necessary to make the pitch of the mesh or grid finer or increase the number of meshes, but this increases pressure loss, increases the secondary pressure of the safety valve and release valve, and reduces the valve capacity. Since this leads to a shortage of solids, it is subject to certain restrictions. However, a moderate pressure loss has the effect of spreading the gas flow in the lateral direction, averaging the heat absorption of each element, and preventing local overheating.

In the above example, if the pitch of the mesh or the grid is made finer, the amount of heat absorbed will be larger than the heat capacity of the element (the temperature of the element will rise faster, and the cooling effect will be reduced by reducing the temperature difference with the gas). In this case, the number of heat absorbing plates 26 may be increased, since the reduction in heat resistance and the heat resistance of the element are likely to become a problem.

In addition, in cases where higher temperature gas continues for a long time, the pressure loss within the water seal drum 20 may be large because the piping from the valve to the water seal drum 20 is long and the pressure loss is large, or there is not enough valve capacity. If the number of heat absorbing plates 26 cannot be increased, for example, as shown in FIG. The opening 27 of the underwater open pipe 22 is placed directly below the element so that it passes only through the heat sink 2.
By placing the lower end of the element 8 at a position below the opening 27, the heat absorbed by the element can be released from the heat radiating plate 28 into the water, suppressing the temperature rise of the element, and expanding the range of materials to be selected. becomes possible. In addition, when installing this heat sink, make sure to secure a space outside the heat sink where water can perform the necessary natural convection heat transfer.

Furthermore, if an even greater cooling effect is required, for example, as shown in FIG. is opened underwater, and the opening 27 of the underwater open pipe 22 is placed directly below the element, and the lower end of the tube plate 30 is located below the frontage 27, as in FIG. When the element 29 is heated by high-temperature gas, the water density changes and some of the water flows inside the element while evaporating, increasing the cooling effect and releasing flammable gas at a higher temperature for a longer period of time. can be done.

Furthermore, in any of the above embodiments, a part of the water in the water seal drum 20 and the generated water vapor are accompanied by gas and released into the atmosphere through the stack 21. Although it is necessary to supply water from the outside by controlling the level, it is more effective to supply water from near the bottom of the water seal drum 2o.

On the other hand, the present invention is not limited to fuel cell power generation plants, but can be similarly applied to chemical plants that require flammable gas release devices.

Further, in order to enhance the cooling effect, fins or protrusions of various shapes may be provided on the element or the heat sink.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

[Effects of the Invention 1] As explained above, according to the present invention, a material having heat resistance and good thermal conductivity is used in the water-sealed drum into which flammable gas is introduced through a pipe open to the water. A plurality of heat absorbers in the form of nets, lattice or perforated plates made of elements are arranged below the water surface in the water seal drum in a horizontal or inclined state, so that heat absorbers are It is possible to provide a combustible gas atmosphere release device that has a simple configuration and can safely release surplus combustible gas to the atmosphere.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a water seal drum showing an embodiment of the present invention;
FIGS. 2 and 3 are configuration diagrams showing other embodiments of the present invention, FIG. 4 is a system diagram showing an example of the system configuration of a conventional fuel cell power generation plant, and FIGS. 5 and 6 are conventional FIG. 1... Fuel N battery, 2... Raw fuel inlet piping, 3...
Steam inlet piping, 4... Reformer, 5... Reforming pipe, 6
... Combustion chamber, 7... Burner, 8... Air inlet pipe, 9... Exhaust pipe, 1o... Reformed gas pipe, 11...
・Converter, 12...Battery fuel pipe, 13...Battery exhaust air pipe, 14...Pack vent valve, 15, 16, 17
．． 18... Safety valve, 19... Differential pressure release valve, 20...
・Water seal drum, 21... Stack, 22... Submersible open pipe, 23... Spray or make-up water valve, 24...
Spray pipe or spray nozzle, 25... desuperheater,
26... Heat absorption plate element, 27... Underwater open tube opening, 28... Heat sink, 29... Hollow element, 30... Tube sheet. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (3)

[Claims] (1) In a device that releases flammable gas from a plant into the atmosphere, the flammable gas is introduced into the water through a pipe open to the water, and the water-sealed drum has heat resistance and good thermal conductivity. A flammable gas characterized by having a structure in which a plurality of net, lattice, or perforated plate-shaped heat absorbers made of elements made of materials are arranged horizontally or inclined below the water surface in a water seal drum. Atmospheric release device. (2) The flammable gas atmosphere release device according to claim (1), characterized in that heat sinks are provided at both ends of the heat absorber in the form of a net, a grid, or a perforated plate. (3) A hollow element is horizontally or inclined, a cylindrical or rectangular tube plate is attached to both ends of the element, and the element is placed under the water surface in the water seal drum with the ends open. A combustible gas atmosphere release device according to claim (1) or (2), characterized in that: