Detection device for detecting a fire-like event

Abstract

The present invention relates to a detection device for detecting a fire-like event occurring in a space which contains a medium or through which a medium flows, the detection device comprising a detector which has a radiation-sensitive detector material and is designed to detect radiation emitted by the fire-like event. The detection device according to the invention exhibits improved properties with respect to interference sources.

Description

[0001] Detection device for detecting a fire-like phenomenon

[0002] The present invention relates to a detection device for detecting a fire-like phenomenon occurring in a space loaded with or through which a medium flows, comprising a detector comprising a radiation-sensitive detector material which is designed to detect radiation emitted by the fire-like phenomenon.

[0003] Furthermore, the present invention relates to a detection system for detecting a fire-like phenomenon occurring in a space loaded with or through which a medium flows, comprising a medium displacement body arranged in the space, and a detection device according to the invention.

[0004] In all areas where mixtures of air and combustible or flammable dust come into contact, fire-like phenomena such as smoldering pockets can form under certain circumstances and conditions.

[0005] A fire-like phenomenon can be understood as a spark, flame, glow or hot particle phenomenon, but also as a smoldering nest.

[0006] As stated below, quoting DE 102 49 743 A1, smoldering nests are clumps of the combustible or flammable dust components present in a mixture, which can heat up to several hundred degrees Celsius due to chemical reactions within them. The outer layers of such smoldering nests, on the other hand, consistently reach temperatures below 100°C. Smoldering nests can cause dangerous and devastating dust explosions. Such dust explosions usually occur when the smoldering nests are carried from the pneumatic conveying line, where an explosion cannot usually occur due to the high dust concentration, into silos or other plant components and burst open. These silos or plant components generally contain explosive dust-air mixtures, which can be caused to explode by a smoldering nest breaking open and the embers exposed in the process.The consequences of such an explosion, triggered by smoldering pockets, are often devastating and can result in significant property damage, injuries, and deaths. The problem described above can also apply to the food industry. Combustible dusts occur in almost every manufacturing process, which are frequently transported by pneumatic conveying lines. Examples include the processing of grain flour, milk powder, corn starch, cocoa powder, and even animal meal.

[0007] According to published statistics, smoldering pockets are the second most common ignition source in dust explosions. For this reason, efforts have long been made to develop reliable devices for detecting smoldering pockets. W. Bartknecht, Explosion Protection (Springer-Verlag 1993), describes a device for detecting smoldering pockets in stationary plant components such as silos, which has been in reliable use for several years. It is based on the detection of CO emitted by the smoldering pockets. However, the detection of CO is not possible in pneumatic conveying lines for technical reasons. Therefore, in this case, hot objects are detected based on their infrared emissions.State-of-the-art detection systems often utilize multiple infrared-sensitive sensors, such as lead sulfide photoconductors, so-called PbS sensors. These sensors are integrated into the pipe wall of the pneumatic conveying line to be monitored in the form of a detector's measuring head. Their infrared-sensitive field of view allows them to view into the pipeline. Glowing particles passing by the detectors emit thermal radiation, which is registered by the detectors or PbS sensors and causes a change in resistance. This change in resistance leads to a change in current or voltage, which represents the measurement signal, which is amplified and further processed electronically.

[0008] In this way, sparks or hot objects within the conveying stream flowing in the conveying line with a surface temperature above approximately 250 °C can be detected. However, this is only possible if additional technical conditions are met, which is not possible in the vast majority of cases in the food industry.

[0009] When observing fire-like phenomena in such media, interference often occurs that reduces measurement sensitivity. These interferences can be caused, for example, by molecular vibrations of organic molecules or molecular components.

[0010] Accordingly, the present invention is based on the object of providing a detection device and a detection system which are improved with regard to sources of interference.

[0011] This object is achieved with a detection device according to claim 1 and a detection system according to claim 10.

[0012] First, as mentioned at the outset, the invention relates to a detection device for detecting a fire-like phenomenon occurring in a space charged with or through which a medium flows, comprising a detector comprising a radiation-sensitive detector material, which is designed to detect radiation emitted by the fire-like phenomenon. The detection device is characterized in that the radiation-sensitive detector material comprises InGaAs, which is radiation-sensitive in a first wavelength range, preferably in the infrared range, particularly preferably in the range from 800 nm to 2700 nm.

[0013] Early detection of fire-like phenomena is an important tool for averting or reducing the potential dangers to people, machinery, and the environment that may arise from fire-like phenomena. Examples of such dangers include fires, explosions, deflagrations, and the like. Early detection of a fire-like phenomenon associated with such a hazard allows for appropriate countermeasures to be taken early on, so that the danger either does not occur at all or can be reduced (contained).

[0014] A "medium" can comprise one or more components. In this context, a "medium" can be understood to mean, in particular, solids, solid particles, dust particles, etc. If such substances or particles are moved, especially at pressures that are higher or lower than normal pressure, the risk of occurrence and thus the danger of flame formation, fire, or explosion (e.g., a dust explosion) increases in the event of a fire-like phenomenon. The same can apply to the static (non-actively moving) storage of media (e.g., under pressure) in a room. Even when a room is "loaded" with a medium, (local) movements can be generated within the medium (e.g., due to pressure fluctuations, temperature gradients, or due to certain material properties), which, in conjunction with a fire-like phenomenon, can lead to an increased risk of ignition or explosion.Situations can also arise in which a smoldering ember falls into a layer of dust or is transported into a silo. Particularly in combination with atmospheric oxygen, hazardous mixtures can form, posing a potential risk of ignition or explosion. Likewise, fluids such as gases or liquids can also be understood as "medium" in the context of the present invention. Pasty or viscous media (e.g., plastic in a (partially) molten, softened, or deformable state) are also possible media.

[0015] A space "loaded" with a medium can be understood as a container (e.g. a silo or a storage chamber) loaded with a solid, particle or granulate bed, in which the medium is stored without active transport (i.e. without active movement induction).

[0016] A space through which a medium flows can be understood as a (at least partially) closed-off conveyor path, conveyor line, conveyor belt, drop shaft, filter, filter system, or conveyor channel in which a medium flow is present and a medium is transported (e.g., mechanically, pneumatically, or otherwise). In a space through which a medium flows, the medium is therefore primarily in a moving state. Depending on the type of medium, the flow velocity of the medium, and the shape and size of the space, media movements can cause, for example, turbulence (particularly in turbulent flow), local particle accumulation, deflagration, etc., which can overall lead to increased friction between particles belonging to the medium, as well as between the particles and the walls of the reservoir.This can be associated with increased frictional heat generation. An increased risk of ignition or explosion can thus arise from ignition sources generated by the movement of the media (as ignition-related phenomena) or from other ignition-related phenomena. Such media storage or media movement occurs particularly frequently in manufacturing, processing, or transport processes in the woodworking industry, the textile industry, the furniture industry, the coal industry, the paper industry, the plastics industry, the metal industry, the food industry (e.g., milk powder production), the luxury goods industry (especially the tobacco industry), the animal feed industry, the leather industry, the rubber industry, the chemical industry, and the gunpowder and firearms industry.These industries often include systems for grinding or comminuting solids or solid mixtures, drying systems, cooling systems, and compression systems, all with their pneumatic or mechanical transport and extraction systems. Dust extraction systems can also be considered media movement.

[0017] The previously mentioned application areas and application examples have in common an increased risk of fire, combustion, or explosion due to the interaction of fire-like phenomena and the medium contained in an associated room. This can occur when fine particles of combustible (e.g., organic) material are present or moved in a high particle density in a room. If a fire-like phenomenon then occurs in a part of the system or machine connected to the room, or in the reservoir itself, this can lead to the aforementioned spark formation and the associated ignition of the medium (even to the point of explosion). This can be intensified by the above-mentioned movement-induced turbulence, deflagration, and heating effects of the media particles. Dust explosions can occur, for example, when fire-like phenomena (as an ignition source) or a suitable fuel (e.g.,The medium in question (in dust form) and oxygen must be present in sufficient quantities. Ignitive phenomena can result, for example, from hot surfaces, flames and hot gases, mechanically generated sparks, electrostatic discharges, smoldering pockets, electrical equipment, or burning metal particles.

[0018] To detect fire-like phenomena early and thus contribute to effective fire, blaze, or explosion prevention, measurement devices are used to (optically) detect such fire-like phenomena. These devices are also known in technical jargon as spark sensors or spark detectors. Spark detectors can be embedded in system-integrated alarm or extinguishing systems or used independently of an alarm or extinguishing system, for example, exclusively for monitoring a room with media flow or media load.

[0019] As already defined at the beginning, a fire-like phenomenon can be understood as a spark, flame, ember or hot particle phenomenon, but also a smoldering nest.

[0020] In such a room, in addition to fire-like phenomena, sources of interference may also be present that can impair reliable detection of a fire-like phenomenon. For example, organic molecules, molecular components, or functional groups of the molecules may vibrate in such a room. The associated vibrational energy, for example in the case of OH or CH, can be associated with radiation in the wavelength range above 2700 nm. If a detector material is used that is sensitive in a wavelength range above 2700 nm (e.g., in the range from 2700 nm to 3500 nm), such vibrations can reduce the detection sensitivity of the fire-like phenomena. This can be improved if necessary by using suitable filters that can filter out the interfering wavelength ranges (e.g., above 2700 nm), although such a solution is technically complex.

[0021] The use of a radiation-sensitive detector material that is radiation-sensitive in a first wavelength range, preferably in the infrared range, particularly preferably in the range from 800 nm to 2700 nm, makes it possible to increase sensitivity and filter out interfering radiation ranges without having to resort to filters. This is because radiation with wavelengths outside the first wavelength range, or outside the infrared range, outside the range from 800 nm to 2700 nm, cannot be detected with such a detector material. As mentioned, the detector material in question is InGaAs (indium gallium arsenide), which is preferably radiation-sensitive in the range from 800 nm to 2700 nm and insensitive outside this wavelength range. The detector material in question is the InGaAs variant also referred to as "extended InGaAs" in the specialist literature.This material can also be radiation-sensitive in a wavelength range from 800 nm to 2600 nm. By limiting the wavelength to this wavelength range, radiation in interfering wavelength ranges is blocked without the need for an additional filter.

[0022] Further embodiments of the invention are specified in the subclaims.

[0023] According to a first embodiment, a detection device according to the invention can be characterized by a window arranged between the detector and the space, which is permeable to radiation with a wavelength in the first wavelength range. The window can protect the detector from the medium or conditions in the space (e.g., from temperature influences, etc.). In this case, the detector is preferably not arranged directly in the space, which can facilitate maintenance of the detection device.

[0024] According to a further embodiment, a detection device according to the invention can be characterized by an optical waveguide that can be arranged with a first end facing the room and a second end facing the detector. Thus, radiation to be detected in the room (e.g., a fire-like phenomenon) can be transmitted via the waveguide toward the detector. Such an arrangement allows the detection device to be arranged outside the room, at least not directly in the room.

[0025] According to a further embodiment, a detection device according to the invention can be characterized by an evaluation unit that is connected to the detector via a signaling connection. The evaluation unit and detector can, for example, be arranged in a common housing of the detection device; however, it can also be provided that the evaluation unit is an external evaluation unit that is connected to the detector via a cable or wireless connection (both can be signaling connections). In this case, the detector can be connected to a signal transmission unit in order to transmit data (e.g., raw data or pre-processed data) to the evaluation unit. Data or commands can also be transmitted from the evaluation unit to the detector, for which purpose the detector can be connected to a signal receiving unit.The mentioned signal transmission unit and the signal reception unit can be a common component.

[0026] According to a further embodiment, a detection device according to the invention can be characterized in that the detection device comprises a housing in which the detector and, optionally, the evaluation unit are arranged. The housing can be designed for installation outside the room, but also for installation inside the room. In the latter case, it must be ensured that the housing has a sufficient service life despite contact with the medium.

[0027] According to a further embodiment, a detection device according to the invention can be characterized by an additional detector that is radiation-sensitive in a second wavelength range that differs from the first wavelength range. This allows larger wavelength ranges to be detected by signal technology. Furthermore, signals from wavelength ranges that differ from the first wavelength range can be taken into account during signal evaluation, signal correction, or signal-to-noise optimization. For example, the additional detector can be a detector for detecting ambient light.

[0028] According to a further embodiment, a detection device according to the invention can be characterized in that the medium is an organic medium, in particular an organic dust. The medium can also be an inorganic or other medium and contain organic components. Especially with organic media, suppressing vibrations with wavelengths above 2700 nm is advantageous in order to increase measurement sensitivity.

[0029] According to a further embodiment, a detection device according to the invention can be characterized in that a filter is assigned to the detector or the further detector, with which radiation of a predetermined wavelength range can be filtered out. The filter can be, for example, a daylight filter, in particular a germanium filter. According to a further embodiment, a detection device according to the invention can be characterized in that multiple detectors and / or multiple additional detectors are provided. Multiple detectors can detect a larger spatial area, possibly also from different observation angles. Furthermore, the provision of multiple detectors, e.g. in the form of a detector array, can increase the measurement sensitivity or minimize interference effects. Redundant detections can be carried out.

[0030] Furthermore, the problem underlying the invention is solved by a detection system for detecting a fire-like phenomenon occurring in a space loaded with or through which a medium flows, comprising a. a medium displacement body arranged in the space, and b. a detection device according to the invention.

[0031] The detection system is characterized in that at least part of the medium is arranged between the detection device and the medium displacement body.

[0032] According to one embodiment of a detection system according to the invention, the space can be a conveying line for the medium.

[0033] According to a further embodiment of a detection system according to the invention, a conveying path for the medium can be formed between a wall of the conveying line and the medium displacement body. This reduces the maximum distance of a fire-like phenomenon to be detected or a medium particle (which can cause the fire-like phenomenon) from the detection device, i.e., the detector. The displacement body thus enables a "closer" observation of the fire-like phenomenon, which has a beneficial effect on the detection probability. At the same time, it is ensured, or the displacement body is arranged, that a conveying flow of the medium through the conveying line is not reduced in relation to the flow cross-section of the conveying line in the region of the displacement body. For this purpose, the conveying line can, for example, be widened in the region of the displacement body.

[0034] According to one embodiment of a detection system according to the invention, the detection device can be arranged inside or outside the chamber, in particular the conveying line. An arrangement inside the chamber can enable even closer observation of fire-like phenomena or particles in the medium. An arrangement outside the chamber simplifies maintenance and accessibility and allows for fewer adverse effects of the medium on the service life of the detection device.

[0035] According to one embodiment of a detection system according to the invention, the detection device can be arranged in the wall of the conveying line. Compared to arranging the detection device within the space or the conveying line, this has less impact on the transport of the medium. Arranging the device in the wall also allows for easier access, e.g., for maintenance purposes.

[0036] According to one embodiment of a detection system according to the invention, the detection device can be arranged in the medium displacement body or in a wall of the medium displacement body. Such a configuration enables particularly "close" observation of fire-like phenomena in the conveying line or the space.

[0037] Further embodiments of the invention are shown in the figures. These show:

[0038] Fig. 1 shows a detection system according to the prior art;

[0039] Fig. 2 shows a detection system according to a first embodiment of the invention;

[0040] Fig. 3 shows a detection system according to a second embodiment of the invention;

[0041] Fig. 4 shows an exemplary structure of a detection device according to a first embodiment that can be used in the detection system according to Figures 1 to 3; Fig. 5 shows an exemplary structure of a detection device according to a second embodiment that can be used in the detection system according to Figures 1 to 3;

[0042] Figures 1 to 3 basically show a detection system for detecting a fire-like phenomenon 4 occurring in a space 3 loaded with or through which a medium 2 flows, comprising a medium displacement body 12 arranged in the space 3, as well as a detection device 1. The space 3 is a conveying line for the medium 2. As can be seen, a conveying path 14 for the medium 2 is formed between a wall 13 of the conveying line and the medium displacement body 12.

[0043] The detection device 1 of Figures 1 to 3 can be designed, for example, according to Figures 4 or 5. It is known from the prior art and as shown in Figure 1 to arrange a medium displacement body 12 in a space 3 (e.g., centered as shown in Figures 1 and 2) and to arrange a detection device 1 in the medium displacement body 12. With such an arrangement, the detection device 1 is difficult to access, for example, for maintenance or replacement purposes.

[0044] It can also be provided, as shown in Figures 2 and 3, to arrange the detection device 1 inside or outside the space 3, in particular the conveyor line.

[0045] It may also be provided to arrange the detection device 1 in the wall 13 of the conveyor line.

[0046] The detection device 1 comprises a detector 5 comprising a radiation-sensitive detector material, which is designed to detect radiation emitted by the fire-like phenomenon 4. At least a portion of the medium 2 is arranged between the detection device 1 and the medium displacement body 12.

[0047] As shown in Fig. 4, a window 6 can be provided between the detector 5 and the chamber 3, which is permeable to radiation with a wavelength in the first wavelength range. The window 6 can also be part of a wall 13 of the chamber 3. The window 6 can also be part of a wall of the medium displacement body 12. The window 6 can be integrated into the walls.

[0048] As an alternative to using a window 6, an optical waveguide 7 can also be provided, which can be arranged with a first end 8 facing the space 3 and with a second end 9 facing the detector 5.

[0049] List of reference symbols

[0050] 1 detection device

[0051] 2 Medium

[0052] 3 rooms

[0053] 4 fire-like appearance

[0054] 5 Detector

[0055] 6 windows

[0056] 7 optical waveguide

[0057] 8 first end

[0058] 9 second end

[0059] 10 Evaluation unit

[0060] 11 signaling connection

[0061] 12 medium displacement bodies

[0062] 13 Wall

Claims

Patent claims 1. Detection device (1) for detecting a fire-like phenomenon (4) occurring in a space (3) loaded with or through which a medium (2) flows, comprising a detector (5) comprising a radiation-sensitive detector material, which is designed to detect radiation emitted by the fire-like phenomenon (4), characterized in that the radiation-sensitive detector material comprises InGaAs, which is radiation-sensitive in a first wavelength range, preferably in the infrared range, particularly preferably in the range from 800 nm to 2700 nm.

2. Detection device (1) according to claim 1, characterized by a window (6) arranged between the detector (5) and the space (3), which window is permeable to radiation having a wavelength lying in the first wavelength range.

3. Detection device (1) according to claim 1, characterized by an optical waveguide (7) which can be arranged with a first end (8) facing the space (3) and with a second end (9) facing the detector (5).

4. Detection device (1) according to one of the preceding claims, characterized by an evaluation unit (10) which is connected to the detector (5) via a signal connection (11).

5. Detection device (1) according to one of the preceding claims, characterized in that the detection device (1) comprises a housing (12) in which the detector (5) and optionally the evaluation unit (10) is / are arranged.

6. Detection device (1) according to one of the preceding claims, characterized by a further detector which is radiation-sensitive in a second wavelength range which differs from the first wavelength range.

7. Detection device (1) according to one of the preceding claims, characterized in that the medium (2) is an organic medium, in particular an organic dust.

8. Detection device (1) according to one of the preceding claims, characterized in that the detector or the further detector is assigned a filter with which radiation of a predetermined wavelength range can be filtered out. Daylight filter, germanium filter closes at 1.5 μm.

9. Detection device (1) according to one of the preceding claims, characterized in that several detectors and / or several of the further detectors are provided.

10. A detection system for detecting a fire-like phenomenon (4) occurring in a space (3) loaded with or through which a medium (2) flows, comprising a. a medium displacement body (12) arranged in the space (3), and b. a detection device (1) according to one of claims 1 to 9, characterized in that at least part of the medium (2) is arranged between the detection device (1) and the medium displacement body (12).

11. Detection system according to claim 10, characterized in that the space (3) is a conveying line for the medium (2).

12. Detection system according to claim 10 or 11, characterized in that a conveying path (14) for the medium (2) is formed between a wall (13) of the conveying line and the medium displacement body (12).

13. Detection system according to one of claims 10 to 12, characterized in that the detection device (1) is arranged inside or outside the space (3), in particular the conveyor line.

14. Detection system according to claim 11, characterized in that the detection device (1) is arranged in the wall (13) of the conveyor line.

15. Detection system according to one of claims 10 to 14, characterized in that the detection device (1) is arranged in the medium displacement body (12) or in a wall of the medium displacement body (12).

Images