Flame arrestor and flameless blast pressure relief device, in particular dust explosion pressure relief

Abstract

The invention relates to a flame arrester with an inlet (E) for burning gases or dust-air mixtures and an outlet (A) for gases or dust-air mixtures which are no longer burning, wherein the flame arrester has a duct system between the inlet (E) and the outlet (A), wherein the duct system has - a branch (V1, V2) connected to the inlet (E), - a junction (Z1, Z2) connected to the outlet (A) and - between the branch (V1, V2) and the junction (Z1, Z2) a first duct (A1, A2) and a second duct (B1, B2), wherein the first duct (A1, A2) and the second duct (B1, B2) begin at the branch (V1, V2) and end at the junction (Z1, Z2) and wherein the direction of the first duct (A1, A2) and the direction of the second duct (B1, B2) at the junction (Z1, Z2) are opposite or almost opposite to each other.

Description

[0001] The present invention relates to a flame arrester such as can be used in a device for flameless explosion venting, in particular dust explosion venting, for example for flameless explosion venting of a container, housing, enclosure, line, or the like in which an explosive mixture, in particular a dust-air mixture, in particular an explosive atmosphere, is present or may arise. The invention further relates to a device for flameless explosion venting, in particular dust explosion venting, comprising such a flame arrester.

[0002] Explosive mixtures may be present or formed in containers, housings, and enclosures, for example, in production facilities, pipes, or other materials during storage or production of goods. The mixture may be intentional, but it may also be caused by error or by accident.

[0003] Unintentional ignition of the mixture, especially the dust-air mixture, can occur. This can lead to an explosion, particularly a dust explosion, in the container, housing, enclosure, pipe, etc. Such an explosion can cause devastating personal injury and property damage. This can result in serious production downtime. To minimize such damage and production downtime, explosion venting devices are advisable and, in some cases, even required.

[0004] The applicant manufactures devices for dust explosion venting under the names "Q-Tube," "Q-Box," and "Q-Ball," among others. These devices are placed over an opening in the object or device to be protected. The Q-Tube, Q-Box, or Q-Ball feature a flame arrester. This consists, for example, of one or more layers of a textile fabric, such as a woven fabric, a knitted fabric, or a wire mesh, held by a cage. The layers can be provided in a package. The wire can, in particular, be a stainless steel wire. Hot gases and, in particular, burning dust-air mixtures escaping from the container, housing, enclosure, etc. to be protected are cooled by the flame arrester, which leads to the extinguishing of the flames. At the same time, dust can also be retained.The layers of the fabric or the packing have a very large surface area, through which heat can be dissipated quickly and in large quantities while simultaneously retaining dust from the gases escaping from the object or device to be protected.

[0005] Dust explosion venting devices such as the Q-Tube, Q-Box, or Q-Ball usually have a rupture disc that closes the opening through which the hot or burning gases are supposed to escape from the object or device to be protected. In the event of a pressure increase in the object or device to be protected, for example due to an explosion, the rupture disc opens and releases the opening through which the dust-air mixture can escape from the object or device to be protected. The flame arresters in the Q-Tube, Q-Box, or Q-Ball are located behind the rupture disc.

[0006] The placement of the flame arrester in the flow path behind the rupture disc has proven successful in the past for several reasons. This prevents the flame arrester from being contaminated by substances present in the object or equipment being protected, especially dust or oil. The large surface area of ​​the stainless steel packing also provides a large surface area to which dust, oil, and other substances can adhere. In the worst case, in the event of a pressure release, these substances could catch fire. The purpose of the flame arrester is then certainly not fulfilled.

[0007] The object of the invention was to propose a flame arrester in which no textile fabrics or stainless steel packings made of a stainless steel mesh or the like are used.

[0008] The object is achieved according to the invention in that the flame arrester is formed between an inlet for burning gases or dust-air mixtures and an outlet for no longer burning gases or dust-air mixtures, a channel system which has a branch connected to the inlet, a junction connected to the outlet and between the branch and the junction a first channel and a second channel, wherein the first channel and the second channel begin at the branch and end at the junction, wherein the direction of the first channel and the direction of the second channel at the junction are opposite or almost opposite to one another.

[0009] This flame arrester splits the burning gas or dust-air mixture entering the duct system through the inlet into two partial streams, which are distributed between the first and second ducts. The gas or dust-air mixture partial streams are transported further in the first and second ducts. The oxygen present in the ducts is consumed by the combustion. At the junction, the partial streams meet with opposite flow directions. This leads to the extinguishing of the flames.

[0010] It is possible that a channel is provided between the inlet and the branch and / or that a channel is provided between the junction and the outlet.

[0011] The extinguishing of the flames can have several causes, each of which can be the cause individually or together. The fact that kinetic energy is lost when the partial flows collide with each other can contribute to the extinguishing of the flames, which can lead to the flow initially coming to a standstill at the junction. The residence time of the hot gases or dust-air mixtures at the junction and in the areas of the duct system adjoining the junction is thereby increased. This can lead to more heat being transported from the gas at the junction and in the area of ​​the duct system adjoining the junction towards the outlet into a body or bodies in which the duct system is formed. These bodies can, for example, be similar to pipes or tubes. It is also possible for the duct system to be formed in one or more connected monoliths, which are manufactured using 3D printing.It could also be the case that the partial streams meeting at the junction steal each other's oxygen, resulting in a lack of oxygen that extinguishes the flames. Furthermore, the colliding partial streams can cause mixing. This can lead to the flames being enveloped by combusted dust-air mixtures, preventing sufficient oxygen from reaching the flames, causing them to suffocate due to a lack of oxygen.

[0012] A similar channel system as provided in the flame arrester according to the invention is also listed / mentioned in the Tesla valve.

[0013] By selecting the geometry of the first and second channels, particularly their cross-sections and / or lengths, it is possible to ensure that the partial streams flowing through the first and second channels arrive at the junction at times that are optimal for extinguishing the flames. Thus, a lower flame front velocity can be achieved in channels with a larger cross-section than in channels with a smaller cross-section. In contrast, transport takes longer in long channels than in short channels.

[0014] In addition, the narrowing or widening of the channels can have an influence on the extinguishing of the flames.

[0015] The branching can be designed so that the gases flowing in at the inlet are split into two partial streams with virtually identical flow directions, which enter the first and second channels. The partial streams can flow laminarly at the branching point. Only further along the channels can they exhibit curves, allowing the channels to meet at the junction from opposite or nearly opposite directions.

[0016] The flame arrester according to the invention can have a plurality of channel systems which have a branch connected to the inlet, a junction connected to the outlet and a first channel and a second channel between the branch and the junction, wherein in each channel system the first channel and the second channel start at the branch of the channel system and end at the junction of the channel system, wherein the direction of the first channel and the direction of the second channel are opposite or almost opposite to each other at the junction of the channel system.

[0017] First channels and / or second channels of two or more of the channel systems can be combined at least in sections to form one channel, in particular to form a first or a second channel.

[0018] It is possible for the duct systems of a flame arrester according to the invention to be arranged in series and / or in parallel. By means of a parallel arrangement, the pressure at the inlet to the flame arrester can be distributed across several duct systems simultaneously. This can reduce the pressure and flow velocity of the incoming gases in the duct systems. By means of a series arrangement of several duct systems, the effect or effects that lead to the extinguishing of the flow running from the inlet to the outlet through a duct system can be achieved several times in succession. This can be particularly useful or even necessary if one duct system or several duct systems arranged in parallel are not sufficient to extinguish the flames.

[0019] Furthermore, it was found that vibrations occur in the flame arrester according to the invention. This was confirmed by the fact that smoke escapes in bursts after the burning gases enter the flame arrester. These vibrations, or the compression and expansion of the gas entering the flame arrester, whose entry into the flame arrester is associated with only a sharp increase in pressure, may also be related to the extinguishing of the flames.

[0020] It is possible for a flame arrester according to the invention to be part of a device for flameless explosion venting, in particular a device for flameless dust explosion venting. This device can then have a rupture disc, a flap, or a valve in addition to the flame arrester. The flame arrester and the rupture disc, a flap, or a valve can be arranged one behind the other in a duct, with the rupture disc, a flap, or a valve blocking a passage through the duct in a non-triggered state and allowing passage through the duct in an open state. The rupture disc, a flap, or a valve can be arranged in the duct upstream of or downstream of the flame arrester.

[0021] Further features and advantages of an embodiment of the invention are described below with reference to the drawings. The same reference numerals are used for identical or similar parts and for parts with identical or similar functions. In the drawings: Fig. 1 a view of a flame arrester according to the invention, Fig. 2 a view of a section along line II-II through the flame arrester in Fig. 1 and Fig. 3 a section of Fig. 2 , which shows the principle of basic operation.

[0022] It is not necessary for a flame arrester according to the invention to have all of the features described below. It is also possible for a flame arrester according to the invention to have only individual features of the exemplary embodiment described below.

[0023] The flame arrester shown in the figures has a housing 1. The housing is essentially rotationally symmetrical. The housing 1 has a straight, hollow-cylindrical first section 11, which delimits an inlet E of the flame arrester. In other embodiments of the invention, the first section 11 could also have a different geometric shape. For example, it could have a square cross-section. An outlet A is provided on an opposite side. This first section is followed by a conical second section 12. The second section 12 expands the diameter or cross-section of the housing (regardless of the cross-section of the first section 11) from the inlet E towards the outlet A. Adjoining the second section 12 in the direction of the outlet is a straight, hollow-cylindrical third section 13, which merges into an arcuate fourth section 14.The third section 13 could also have different geometric shapes in other embodiments of the invention. For example, it could also have a square cross-section. This fourth section 14 has an inward curve of approximately 180°. Adjoining the fourth section 14 is a straight, hollow-circular, cylindrical fifth section 15. This fifth section 15 encloses the outlet A of the flame arrester. The fifth section 15 could also have a different geometric shape in other embodiments of the invention. For example, it could also have a square cross-section.

[0024] Three guide means 21, 22, 23 are arranged within the housing. The guide means 21, 22, 23 are also rotationally symmetrical. They are connected to the housing 1 via connections not shown in the figures. The guide means also do not have to be rotationally symmetrical and can have different shapes in other embodiments of the invention.

[0025] The first guide element 21 of the three guide elements 21, 22, 23 is a ring with a straight outer surface 211 and a straight inner surface 212. A side 213 facing the inlet is also straight. It forms an obtuse angle with the outer surface 211 and an acute angle with the inner surface 212. A side 214 facing the outlet is curved, in particular semicircular, toward the outlet.

[0026] The second guide means 22 is a complexly shaped disc. It has a side 221 facing the inlet, which has a groove with a tip 222 in the center. The groove has an arcuate, in particular circular arc-shaped groove base. The arc extends approximately 180°. A side 223 facing the outlet has a tip 224 that is symmetrical to, or at least similar to, the tip on the inlet side of the second guide means and points toward outlet A. Between the tip and an outer edge 225 of the second guide means 22, the side 223 of the second guide means 22 facing outlet A has an approximately S-shaped contour.

[0027] The third guide means 23 is again a ring. The ring has a drop-shaped cross-section. It has a straight outer side 231, which is adjoined on the outlet side by a bend 232, which forms a convex side facing the outlet and a slightly convex inner side of the ring. Together with the outer side 231, this bend forms a tip 233 pointing toward the inlet E.

[0028] Two channel systems are formed by means of the housing and the three guide means 21, 22, 23. Each of these channel systems has a first channel A1 or A2 and a second channel B1 or B2. These are arranged in series between the inlet E and the outlet A against the direction of flow. Each channel system has a branch V1, V2 on the inlet side and a junction Z1, Z2 on the outlet side. The first channel A1, A2 and the second channel B1, B2 begin at the branch V1, V2 of each channel system. The first channel A1, A2 and the second channel B1, B2 meet again at the junction Z1, Z2 of each channel system. The direction of the first channel and the direction of the second channel are opposite or almost opposite to one another.

[0029] The first channel A1 of the first channel system is delimited by the inner side 212, the outlet-facing side 214, and the outer side 211 of the first guide means 21, on the one hand, and the inlet-facing side 221 of the second guide means 22, on the other hand. The second channel B1 of the first channel system is delimited by a part of the inner side of the second section 12 of the housing 1, on the one hand, and the inlet-facing side 213 of the first guide means 21, on the other hand.

[0030] The first channel A2 of the second channel system is bounded by a part of the inside of the third section 13 and the inside of the fourth section 14 of the housing 1, on the one hand, and by the outside 231 and a part of the bend 232 of the third guide means 23, on the other hand. The second channel B2 of the second channel system is bounded by a part of the bend 232 of the third guide means 23, on the one hand, and the side 223 of the second guide means 22 facing the outlet, on the other hand.

[0031] In the Figure 3 , only half of the flame arrester is shown in section.

[0032] How the channels A1, A2, B1, B2 are flowed through when an explosion wave enters the flame arrester is described in the Figure 3indicated by arrows. The burning dust-air mixtures entering the flame arrester through inlet E are distributed between the first duct A1 and the second duct B1 of the first duct system. The partial flow flowing through the first duct A1 is represented by solid-filled arrows. The partial flow flowing through the second duct is represented by crossed-filled arrows.

[0033] Compared to the incoming gas flow, the directions of the partial flows are changed by the course of the channels A1, A2, B1, B2 so that the partial flows meeting at the junction Z1, Z2 have opposite or almost opposite directions.

[0034] The Figures 1 to 3 The flame arrester shown can be connected several times in series to form a larger flame arrester. It is also possible to Figures 1 to 3The flame arrester shown can be arranged several times next to each other to form a larger flame arrester. The dust-air mixture or gas mixture flowing into the flame arrester can thus be divided several times.

[0035] It is also possible to use an elongated housing and elongated guide elements instead of a rotationally symmetrical housing and rotationally symmetrical guide elements, the cross-sectional profile of which corresponds to the contours of the Figures 2 and 3 corresponds to the cut surfaces of the housing and the conductive means shown.

Claims

1. Flame arrester with an inlet (E) for burning gases or dust-air mixtures and an outlet (A) for non-burning gases or dust-air mixtures, characterized by that the flame arrester has a duct system between the inlet (E) and the outlet (A), that the channel system - a branch (V1, V2) connected to the inlet (E), - a junction (Z1, Z2) connected to the outlet (A), and - between the branch (V1, V2) and the junction (Z1, Z2) a first channel (A1, A2) and a second channel (B1, B2), that the first channel (A1, A2) and the second channel (B1, B2) start at the branch (V1, V2) and end at the junction (Z1, Z2) and that the direction of the first channel (A1, A2) and the direction of the second channel (B1, B2) at the junction (Z1, Z2) are opposite or almost opposite to each other.

2. Flame arrester according to claim 1, characterized by - that a channel is provided between the inlet (E) and the branch (V1, V2) and / or - that a channel is provided between the junction (Z1, Z2) and the outlet (A).

3. Flame arrester according to claim 1 or 2, characterized in that the channels (A1, A2) of the channel system are formed in pipes or in one or more monoliths.

4. Flame arrester according to one of claims 1 to 3, characterized in that a minimum cross-section of the first channel (A1, A2) is larger than a minimum cross-section of the second channel (B1, B2).

5. Flame arrester according to one of claims 1 to 4, characterized in that a length of the first channel (A1, A2) is greater than a length of the second channel.

6. Flame arrester according to one of claims 1 to 5, characterized in thatthe first channel (A1, A2) and / or the second channel (B1, B2) has / have tapering or widening portions.

7. Flame arrester according to one of claims 1 to 6, characterized in that starting from the branch (V1, V2), the first channel (A1, A2) and the second channel (B1, B2) have almost the same direction.

8. Flame arrester according to one of claims 1 to 7, characterized in that the first channel (A1, A2) and / or the second channel (B1, B2) have at least one curve between the branch (V1, V2) and the junction (Z1, Z2).

9. Flame arrester according to one of claims 1 to 8, characterized in thatthe flame arrester has a plurality of duct systems which have a branch (V1, V2) connected to the inlet (E), a junction (Z1, Z2) connected to the outlet (A) and a first duct (A1, A2) and a second duct (B1, B2) between the branch (V1, V2) and the junction (Z1, Z2), wherein in each duct system the first duct (A1, A2) and the second duct (B1, B2) begin at the branch (V1, V2) of the duct system and end at the junction (Z1, Z2) of the duct system, wherein the direction of the first duct (A1, A2) and the direction of the second duct (B1, B2) in each duct system are opposite or almost opposite to one another at the junction (Z1, Z2) of the duct system.

10. Flame arrester according to claim 10, characterized in that the duct systems are arranged in series and / or parallel.

11. Use of a Tesla valve principle in a flame arrester, wherein the Tesla valve is arranged opposite to its flow direction between an inlet (E) and an outlet (A) of the flame arrester.

12. A flameless explosion venting device comprising a flame arrester and a rupture disc, a flap or a valve arranged one behind the other in a duct, wherein the rupture disc, the flap or the valve blocks a passage through the duct in a non-triggered state and allows passage through the duct in an open state, characterized by that the flame arrester is a flame arrester according to one of claims 1 to 11.

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