FI126021B - Method for extinguishing a biomaterial fire - Google Patents

Description

METHOD FOR EXTINGUISHING A BIOMATERIAL FIRE

The invention relates to a method for extinguishing a fire of biomaterial, wherein the method is to remove non-combustible biomaterial around the combustible biomaterial and to supply water to the combustible biomaterial to extinguish the fire.

It is generally known that when stacked in chambers, chips, peat or other similar biomaterial generate heat inside the chambers. The generation of heat may be due to a degradation reaction in the biomaterial or to fungi growing in the biomaterial which generate heat. Within the hernia, the temperature of the biomaterial can rise to such an extent that, together with the gases produced in the hernia, the heat causes the hernia to ignite. Fields of biomaterials, such as peat bogs and peat piles, can also ignite, for example as a result of an external spark.

In general, for example, woodchips contain tens, even hundreds of thousands of cubes of biomaterial. However, the proportion of biomaterial combustible in the combustible stoma of the total biomass constituting the stomach is quite small, generally less than 10% of the biomaterial of the stoma.

In biomaterial, the fire proceeds relatively slowly and steadily. The extinction of a flame chips fire is generally carried out in two stages. In the first phase, the rescue unit will turn off the visible flames and ensure that the fire will not spread to targets outside the flare. In the next step, the responsibility for the extinction rests with the owner of the biomaterial. At this point, the removal of biomaterial around the combustible biomaterial is started, and water is injected into the biomaterial, and in particular into the fireboxes. The biomaterial is moved at this stage to any other areas or adjacent to the existing application line, depending on the space available. A biomass fire, such as extinguishing a chip fire, typically takes a total of 1-2 weeks, depending on the size of the biomaterial area and the resources used. Post-extinction is generally carried out by contract fire brigades together with the owner of the application and their contractors. The fire brigade is primarily concerned with transporting fire extinguishing water and borrowing / renting fire fighting equipment for other extinguishers. Typically, during firefighting, the entire chipwood material is treated once and a portion more than once during firefighting.

Typically, the highest cost is incurred after retirement. The costs of post-extinguishing are water transport, staff wages and the costs of machinery and cars used in material treatment. In addition, significant costs arise from the loss of energy content due to the wetting of biomaterials. Of course, the cost is also generated by the biomass lost through combustion, but conventionally these losses are relatively small in value compared to other costs.

The problem with conventional extinguishing is its laborious and costly implementation, which can take weeks for a large area or heap of biomaterial and can take large amounts of water. In addition, the extinguishing method at least partially contaminates the biomaterial.

It is an object of the invention to provide a method for extinguishing a fire of biomaterial which is more accurate than prior art methods, by means of which the fires in the biomaterial can be extinguished more accurately with less water consumption. Characteristic features of the present invention are apparent from the appended claim 1.

This object can be achieved by a method of extinguishing a biomaterial fire, which involves removing non-combustible biomaterial around the combustible biomaterial, searching for the combustion channel formed by the combustible biomaterial by removing the biomaterial, and injecting water over the combustible biomaterial and Due to the draft acting on the combustion duct, the carbon dioxide formed by sublimation of the carbon dioxide residue is transported to the fireboxes, displacing the oxygen needed for combustion from the fireboxes and lowering the temperature of the firebox. In addition, when the biomaterial fields are extinguished, for example, the heavier-than-air carbon dioxide is pressed downward in the combustion duct and enters the firebox. Oxygen displacement and drop in temperature in the fire duct cause the fire to extinguish. By the method of the invention, fireboxes in the biomaterial pile can be extinguished without accurately wetting the entire biomaterial pile or area with water, thereby avoiding the laborious biomaterial treatment step.

In this context, the term "predominantly carbon dioxide ice" means that carbon dioxide may also be fed in the first stage of quenching only as gas, but that the main stage of quenching, ie more than 90% of the time used for quenching, is supplied as carbon dioxide.

Preferably, in the process, carbon dioxide is fed as carbon dioxide ice only. This eliminates the need for gaseous carbon dioxide feeders for extinguishing.

Preferably, in addition to the carbon dioxide, water is fed into the combustion duct. Water also extinguishes fires and facilitates the spread of carbon dioxide in the fire duct.

Preferably, a fire extinguishing line is provided at the mouth of the fire duct to accommodate the external dimensions of the mouth of the fire duct to supply water and carbon dioxide to the fire duct. The fire extinguishing pipe ensures the passage of carbon dioxide into the fire ducts and thereby into the fireboxes. In addition, the extinguishing line supports the water and carbon dioxide ice feeders in the correct position.

Preferably, the water to be fed is sprayed into the fire duct. As a mist, the surface area of the water increases, which increases its extinguishing efficiency. In addition, water mist is better transported in the fire duct. At the same time, the amount of water used for extinguishing can be reduced.

The pressure used for water spraying may be greater than 150 bar, preferably about 200 bar. When fed at this pressure, the water will form a droplet size small enough to effectively propagate the mist through the fire duct.

The amount of biomaterial in the fire may be more than 1000 m3, preferably more than 10,000 m3. In this context, it is meant the total amount of biomaterial that is subject to ignition, of which the proportion of combustible biomaterial is preferably less than 10%. For biomass cassettes of this size, fire extinguishing by conventional methods is particularly difficult and expensive.

In this context, carbon dioxide ice may also be referred to as carbonated ice or dry ice. When exposed to water, carbon dioxide is sublimated to a large amount of gaseous carbon dioxide. One liter of carbon dioxide ice produces about 650 liters of carbon dioxide gas, which displaces oxygen from fire ducts and fires. Further, the release of carbon dioxide gas as a result of sublimation is rapid and the expansion of the gas directs the carbon dioxide deeper into the combustion channel. As carbon dioxide ice, the storage and transport of carbon dioxide is simple and does not require heavy storage tanks as would be needed for the storage of gaseous carbon dioxide.

The carbon dioxide residue may be introduced into the feed water in the form of granules of 1 to 30 mm, preferably 3 to 20 mm. Such granules are easily transported with the feed water and are therefore easily transported to the fire channels with the feed water.

Preferably, the carbon dioxide is fed into the water in a quenching tube, in which the carbon dioxide is sucked into the water supplied by the water under reduced pressure. With the use of a fire extinguishing line, no separate equipment is required for the supply of carbon dioxide, but the supply can be carried out in connection with the supply of water. In this connection, the extinguishing tube acts as an injector.

Preferably, the biomaterial is a biomaterial pile. In such fires, extinguishing firebreaks by prior art methods is particularly laborious when firebreaks are located near the bottom of the pile.

Preferably, carbon dioxide ice and water are fed to the end of the combustion duct from which the draft draws oxygen into the combustion chamber. The carbon dioxide sublimed from the carbon dioxide ice and the water mist are then transported, assisted by draft, to the firebox.

According to another embodiment, carbon dioxide is introduced into the combustion duct by means of a screw conveyor. In this case, a separate extinguishing tube as an injector is not required to supply carbon dioxide.

According to a third embodiment, the carbon dioxide used at the beginning of the extinction is supplied to the combustion duct as gas. In gaseous form, carbon dioxide can be stored for much longer than carbon dioxide ice.

Preferably, the biomaterial is wood chips. Wood chips are flammable as a material and, on the other hand, they do not want to be watered, since watering makes it difficult to continue using wood chips, especially in heat production.

According to a fourth embodiment, the biomaterial is peat. Peat is also extremely flammable and it is desirable to avoid watering it because of its high water-binding capacity.

According to a fifth embodiment, the biomaterial is in the form of a biomaterial field. The extinguishing method according to the invention is also applicable in this case where the fire ducts are close to the surface of the field.

According to a sixth embodiment, the water may be injected into the fire duct. Such a method of supplying water does not require a separate high-pressure pump, but on the other hand the flow of water in the fire duct is weaker than when spraying.

The biomaterial to be quenched by the process of the invention is porous and contains at least 30%, preferably more than 40% by volume of air. In such biomaterials, the airflow is ducted and allows the fire to be extinguished using clear fire ducts. The biomaterial to be extinguished may be wood, such as wood chips, chips or energy wood, peat, compostable material or any similar biomaterial where the area or pile of biomaterial spontaneously ignites.

With the method of the invention, extinguishing large pieces of biomaterial is much faster and more efficient than prior art methods. With the use of carbon dioxide, the extinguishing can be applied directly and individually to the combustible biomaterial, thus completely avoiding the irrigation of the heap or field biomaterial. In addition, the use of carbon dioxide ice is not detrimental to the further use of the biomaterial. Further, when using the method of the invention, the amount of water used for extinguishing can be reduced by up to 80%, since not all biomaterials need to be watered.

The idea of the invention is based on the porosity and channel-like structure of a biomaterial heap or similar biomaterial field. When the biomaterial is chips in the baseline, one wood cubic meter becomes about 2-2.5 bulk cubic meters, that is, more than half of the volume of the chips is air, although the chips are compacted or moved on heavier work machines such as wheel loaders. In other words, one chip cube contains about 0.4 m3 of wood and 0.6 m3 of air. This lays the foundation for the channel structure of the chip. The same is true, for example, of peat bogs and peat fields, which contain a considerable amount of air per volume. As the biomaterial burns, the ductility increases during the fire, as the fire progresses in a smaller fire duct, "continuously" feeding the biomaterial from the edges of the fire duct, thereby gradually increasing it. Fire ducts are formed as biomaterial burns, resulting in even fewer channel-like areas from which the biomaterial has been burned. The fire ducts generally extend horizontally, but with sufficient porous biomaterial or draft in the fire duct, the fire duct is directed upward toward the top or tops of the pile or field. In most cases, the ignition sites are located 1-2 meters above ground level in the lower parts of the biomass pile, and the horizontal ignition areas are usually a few meters, usually 2-4 meters from the edge of the pile. From these, the fire ducts proceed randomly toward the middle and upper portions of the biomaterial pile. In the case of peat, the starting situation is not as clearly porous and channel-like as the chamfering, but the fire propagation is similarly channel-like.

The extinguishing method according to the invention utilizes the structure and properties of a heap of biomaterials and especially fire ducts. Fire ducts have fewer structures than non-combustible biomaterial, in other words, have more air space than the rest of the biomaterial. The fire ducts create a natural draft, or airflow, which intensifies as the fire progresses and intensifies in the fire duct. Especially towards the top of the biomaterial pile, the fire ducts form a chimney-like structure with a strong draft. The draft draws in flue gases outwards from the vertical firebox and preferably inwards from the horizontal firing channels into which the water mist and carbon dioxide are fed. In the extinguishing process of the invention, water mist and carbon dioxide ice, both together or separately, are preferably used as the extinguishing agent. The preferred alternative is to use both extinguishing agents simultaneously, but in some situations carbon dioxide can be used almost alone, with water spray only occasionally using carbon dioxide to enhance sublimation.

The invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 is a schematic view of an initial embodiment of a first embodiment of the method of the invention when a fire is ignited,

Figures 2-3 illustrate the steps of a first embodiment of the method of the invention wherein the biomaterial is removed around the combustible biomaterial to find a combustion channel,

Figure 4 illustrates the steps of a first embodiment of the method according to the invention in which quenching is initiated by supplying carbon dioxide ice and water to the combustion duct,

Figure 5 is a side elevational view of the use and structure of a fire extinguishing tube preferably used in the method of the invention,

Fig. 6 is a side elevational view of the use and construction of a fire extinguishing tube preferably used in the method of the invention,

Figure 7 shows the step of the first embodiment of the method according to the invention in which the biomaterial has been extinguished,

Figures 8-11 show the steps of another embodiment of the method according to the invention.

The method according to the invention is suitable for extinguishing a number of different pieces of biomaterial. Advantageous applications include different heaps of biomaterials, but also different fields of biomaterials such as peat fields.

Figure 1 is a schematic view of a first embodiment of a first embodiment of the method of the invention. In this embodiment, the extinguishable biomaterial fire is in the chipping seam. From now on, only the term heap 22 is used in simplified terms in the biomass heap 22. In the extinguishing method of the invention, at least one fire duct 14 in the biomaterial heap 22 is excavated in a similar manner to the conventional method of FIGS. In other words, the biomaterial 11 is removed around the combustible biomaterial 12, for example in a second heap 23, until the combustible or combustible biomaterial in the combustion duct 14 is found. Removal of biomaterial 11 can be initiated at the edge of the heap 22, which is closest to the point where the smoke 19 exits the heap 22. Generally, the fire duct is searched on the sides of the heap, although the fire duct may be closer to the heap surface. This is because there is often a considerable distance from the heap to the bottom of the heap where the fire base is likely to be located. In addition, it may be difficult or impossible to get the excavator over a steep-edged pile. The detection of the fire channels 14 can be facilitated by the temperature sensors 18 mounted in the heap 22. In Figure 1, the size of the temperature sensors is not proportional to the dimensions of the heap or excavator. The temperature sensors 18 can be manually inserted into the heap 22 up to a depth of about 1.5-2. Deeper installation of temperature sensors 18 requires mechanical aids as the friction of the biomaterial 11 of the heap 22 becomes so large that the temperature sensor 18 cannot be pushed deeper by hand. For deeper-mounted temperature sensors, a mounting hole must be drilled, for example, using a drill with an extension arm, and a temperature-measuring probe may be used to install the temperature sensor. An installation tube can also be used to install the temperature sensor, which is left in place.

Once the fire duct 14 has been found, water is preferably supplied to the mouth 20 of the fire duct 14 to quench the visible fire while providing reasonable working conditions for the actual supply of the extinguishing agent to the fire duct. The water supply, i.e. spraying or spraying, can be done mainly using conventional fire extinguishing equipment, for example using the fire extinguishing equipment 25 of the fire truck of Figure 4. In addition to conventional extinguishing equipment, a high pressure pump is preferably needed to provide sufficient pressure for water spraying. Unlike the figures, the extinguishing equipment may also be considerably lighter and it should be understood that sufficient extinguishing equipment may consist, for example, of a high pressure pump and a water tank connected to the tractor's hydraulic system and the necessary high pressure hoses.

The carbon dioxide and water acting as the extinguishing agent may be fed to the fire duct 14 via a separate feeder extinguishing line 26 which may be supported at the mouth 20 of the fire duct 14. 5 and 6, the extinguishing tube 26 may be a structure having a tubular portion 28 for supplying water and carbon dioxide, and a collar 30 disposed around the tubular portion 28, preferably covering the sides of the mouth 20 of the combustion channel 14 at a distance d. For example, the distance d may be approximately 50 cm in its direction. The collar 30 prevents traction in the wrong direction when the pressure at the orifice 20 exposed in the combustion duct 14 increases as the carbon dioxide ice is fed. The first end 32 of the extinguishing pipe 26 is intended to be provided about 30 cm to 50 cm inside the fire duct 14 and the second end 34 remains approximately 30 cm outside the fire duct 14. The tubular member 28 may include support means 36 for carbon dioxide to support the nozzle 46 of the supply tube 42 and trough 50, and the high pressure hose 44 for supplying water. Further, the collar 30 of the extinguishing tubing 26 may include fastening means 38 for anchoring the extinguishing tubing 26 to the biomaterial 11. The securing means 38 may be anchoring spikes 40, for example, inserting into the biomaterial 11. 11 to a few tens of centimeters. Preferably, the high pressure hose 44 also includes a valve 48 for adjusting the amount of water 70 to be supplied. It will be appreciated that the fire of the biomaterial can be extinguished without the use of a fire extinguishing line, but in this case the effectiveness of the extinguishing is lower.

Carbon dioxide 80 is fed into the combustion duct as carbon dioxide ice 60, preferably with water mist 70. A nozzle 46 preferably used for atomizing water, i.e. a mist nozzle, may be mounted to a depth of a few tens of centimeters in a fire extinguishing tube, while carbon dioxide residue 60 may be introduced near, adjacent, front or rear of the spray nozzle 42 or trough. The flow of water 70 sprayed at a high pressure of more than 150 bar, preferably about 200 bar, causes a vacuum of the carbon dioxide ice 60 in the feed pipe 42 which absorbs the carbon dioxide 60 according to the water 70. Carbon dioxide 60 may be fed to the feed tube 42 by gravity using the feed pan 50. Upon initiation of spraying into the combustion duct 14, water mist 70 and carbon dioxide ice granules 60 come into contact, whereupon the carbon dioxide ice granules sublimate very rapidly, releasing about 650 times the amount of carbon dioxide 80 as gas compared to carbon dioxide 60 in volume. At the same time, water mist is fed to the fire duct under strong pressure. These two things, along with the draft naturally occurring in the fire duct, cause the extinguishing agents, i.e. water and carbon dioxide, to propagate in the fire duct. As the extinguishing agents proceed in the fire duct, they extinguish the fire continuously by displacing the oxygen required for combustion and cooling the already extinguished area of the fire duct, thereby reducing the risk of the fire duct re-igniting as shown in Figure 7. This type of extinguishing method is particularly well suited for extinguishing chip joints. In Figure 7, reference numeral 14 'refers to a extinguished fire duct.

If the water to be fed to the fire ducts is injected into the fire ducts, the supply pressure can be considerably lower, for example, below 20 bar. In this case, carbon dioxide can be fed to the mouth of the combustion duct using, for example, a screw conveyor. However, water spraying is the preferred embodiment of the invention.

The amount of water fed to a single fire duct may be from 15 to 50 L / min, with respect to which the carbon dioxide ice may be used in an amount of 0.5 to 20, preferably 1 to 10% by weight relative to the amount of water supplied. Carbon dioxide ice can also be used in excess of 20% by weight with respect to water, but the cost of carbon dioxide ice increases. The amount of water to be fed and the amount of carbon dioxide ice may vary depending on the size of the fire and the fire channel.

Alternatively, carbon dioxide may also be supplied directly in gaseous form by pressure during the first stage of quenching, but then the extinguishing equipment must also include devices for introducing gas into the fire duct with water. However, the advantage of the gaseous feed is that the gas can be stored for much longer than the carbon dioxide ice, whereby the gas can be used, for example, for first extinction before the carbon dioxide ice can be delivered to the combustion site.

Unlike the embodiment described above, the extinguishable biomaterial fire may also be present in the biomaterial field, preferably in the peat section. If the biomaterial to be extinguished is a peat bog, the search for fire ducts is different from the first embodiment. Figures 8 to 11 show steps of extinguishing a field biomass fire in another embodiment of the method of the invention. The basic principle is still the same, i.e., non-combustible biomaterial 11 is removed around the combustible biomaterial 12 until the combustion channel 14 is found. Temperature sensors can be used as an aid, but the fire ducts are often so close to the surface that the sensors can be manually pushed deep enough. Frequently, rising smoke also exposes the fire ducts of the peat bog more easily than heap fires.

After the fire duct has been found, water and carbon dioxide ice can be extinguished in the same way as in the firing of a biomaterial pile. The amount of water used in peat bogs is smaller than that used to quench the biomaterial pile, and the natural draft of the fire channel is very small, almost non-existent with respect to the draft of the stacked fire channel. The location of the fire channel and the specific gravity of carbon dioxide in the extinction can be effectively utilized in the peat bog. Carbon dioxide is pressed down heavier than air naturally down the fire ducts. Again, the sublimation of the carbon dioxide particles and the generation of carbon dioxide gas is enhanced by the use of water mist to provide sufficient carbon dioxide to form in the combustion channel in a short period of time.

In extinguishing peat bogs, carbon dioxide ice can be used almost alone, and water fog is only occasionally used to enhance sublimation to carbon dioxide. For example, water mist can be applied once per minute for 10 seconds. Such situations, in which the carbon dioxide ice is used almost exclusively, are, first and foremost, fire-extinguishing of the peat bog, where the draft is not as clear as the draft and where the fire channels are lowered. In such situations, the carbon dioxide sublimed / formed from the carbon dioxide ice will significantly fill the fire duct, lowering the oxygen content of the fire area while cooling the fire area.

Although it is shown in the figures that a fire from a biomaterial is started to be extinguished from one direction, it should be understood that several fire ducts may be extinguished simultaneously in a combustible seal or area, depending on the amount of equipment used. This can speed up the extinction of the fire.

Claims (11)

A method of extinguishing biomaterial fire, according to which the method of combustible biomaterial (11) around the burning biomaterial (12) is removed and water (70) is applied to the burning biomaterial (12) to extinguish the fire, characterized in that according to the method one of the burning biomaterial (12) formed fire channel (14) is searched in the biomaterial (11) by removing biomaterial (11) and carbon dioxide (80) is fed, mainly as carbon dioxide (60), to the fire channel (14) to extinguish the fire. Method according to claim 1, characterized in that in the opening (20) of the fire passage (14) a extinguishing pipe (26) which follows the opening dimension of the fire passage (14) for supplying water (70) and carbon dioxide (60) to the fire passage is placed (14). Method according to claim 1 or 2, characterized in that the amount of biomaterial (11) in connection with the fire is over 1000 m3, preferably over 10000 m3. Method according to any one of claims 1-3, characterized in that the water (70) to be fed is sprayed as a water mist in the fire channel (14). 5. A method according to claim 4, characterized in that the pressure used for dimming the water (70) is above 150 bar, preferably about 200 bar. Process according to any one of claims 1-5, characterized in that said carbon dioxide (60) is fed to the water (70) to be fed as grains in the size of 1-30 mm, preferably 3-20 mm. Process according to any one of claims 1-6, characterized in that the carbon dioxide (60) is fed to the water (70) in said extinguishing pipe (26), whereby the carbon dioxide (60) is suctioned by means of the water (70) under pressure. the water (70) to be fed. Method according to one of claims 1-7, characterized in that biomaterial (11) is removed from the biomaterial pile (22). Method according to any one of claims 1-8, characterized in that said biomaterial (11) is chips. 10th Process according to any one of claims 1-7, characterized in that said biomaterial (11) is peat.