EP2461099B1 - Check valve for an exhaust gas line - Google Patents

Description

The invention relates to a Rückströmsperre for an exhaust pipe of a combustion device, wherein the Rückströmsperre a can be installed in a vertical portion of the exhaust pipe body, an inside formed in the tubular body valve seat for at least one float, which can be lifted by vertically upwardly flowing gas from the valve seat, and at least one downstream circumferential and radially inwardly disposed in the tubular body circumferential groove, which is bounded by a radially inner peripheral wall portion and a radially outer peripheral wall portion, wherein the radially inner peripheral wall portion and the radially outer peripheral wall portion formed inside the tubular body and the peripheral edge of the radially inner peripheral wall portion of the valve seat for forms the at least one float.

Rückströmsperren known type, for example, equipped with simple valve bodies or flaps that open or close depending on the gas pressure. The provision in known systems is carried out either by means of the weight of the flaps or by means of restoring elements, such as springs.

A Rückströmsperre of the type mentioned is, for example, in the DE 199 06 736 C1 described. There is in a tubular body, a float with an upstream guide member in the form of a peg-like approach, which is guided on the inner surface of guide webs, wherein the guide webs are arranged substantially radially inwardly disposed on the inside of the tubular body.

From the DE 443 238 C a shut-off device for smoke ducts is known in which by installing two gate valves a lock chamber is divided. The lock room is connected to the outside air by a special Opening associated with a termination device, wherein the termination device has a seat with an annular groove, in which a diving bell can enter. The ring groove is filled with loose dry sand.

From the DE 23 46 515 B1 For example, an industrial flue gas stack with a steel flue tube suspended in an outer jacket tube is known, the steel flue tube having a liquid submerged compensator fitted over the mouth of the flue gas connection channel at the bottom.

Furthermore, a Rückströmsperre of the type mentioned in the DE 100 37 967 C1 known. In this Rückströmsperre the float, which can be lifted by upward flowing exhaust gas from the valve seat, at least two subsections, each next-larger subsection forms an additional valve seat for the next-smaller subsection.

Although these types of backflow barriers have proven successful, it has been found that they are capable of improvement in design, manufacture and technical performance. For example, non-return valves of the type mentioned are produced as plastic injection molded parts. However, the production of plastic injection molded parts of large dimensions is difficult, which should have an extremely low distortion. A delay of the components, such as the float, directly affects the leakage value and the tightness of the entire backflow preventer. Furthermore, the components of the non-return valve are exposed as a result of the flowing exhaust gas massive thermal stresses during operation, which can additionally cause a delay of the components.

The invention is therefore an object of the invention to provide a solution that provides a simple, low cost manufacturing technology and particularly efficient backflow barrier of the type mentioned in a structurally simple manner and beyond the known from the prior art problems for injection-molded Components of a backflow preventer triggers.

In a backflow preventer of the type described, this object is achieved in that the peripheral edge of the at least one floating body protrudes radially beyond the radially inner peripheral wall portion and having an upstream facing axial approach, the upstream of the at least one floating body on the valve seat in the axial direction extends into the circumferential groove, wherein forms in the float seat on the valve seat by a fluid located in the circumferential groove of the axial shoulder together with the fluid forms a gas-tight fluid barrier.

Advantageous and expedient refinements and developments of the invention will become apparent from the dependent claims.

The invention provides a possibility with which a structurally simple way of providing an improved backflow barrier for an exhaust gas line of a combustion device is available. The invention thus creates the prerequisite for the fact that non-return valves with large diameters and, consequently, also combustion devices with larger amounts of exhaust gas, such as condensing units with high outputs, can be connected to a non-return valve according to the invention. In this case, the radially inner peripheral wall portion and the radially outer peripheral wall portion bounding the radially inwardly disposed in the tubular body circumferential groove may be part of the inner wall of the tubular body or formed on the inner wall of the tubular body. When the combustion device is at rest, the float rests on the valve seat. Liquid, which is formed downstream of the float can be passed through the axial extension of the float in the circumferential groove, so that immersed in sufficiently accumulated liquid, the axial approach in the liquid. By immersion in the accumulated liquid of the axial extension of the float together with the liquid forms a fluid barrier in the manner of a fluid sealing seat, so that the float is sealed gas-tight. That way you can Inaccuracies in the manufacturing process of the float due to component distortion are compensated because the liquid fluid or the liquid of the outer contour and in particular of the peripheral edge formed axial approach of the float adapts.

To ensure the last-mentioned advantageous property regardless of the accumulated amount of liquid, the circumferential groove is filled with a fluid or liquid before startup of the non-return valve, so that the upstream-facing axial extension of the float in resting on the valve seat in the located in the circumferential groove Dipping fluid.

Furthermore, in order to favor the outflow of excess condensate or fluid out of the circumferential channel to the outside, it is advantageous if the peripheral edge of the radially outer peripheral wall section has, at least in sections, a bevel extending radially outward and upstream.

In order to additionally prevent solid particles of the exhaust gas or heavy sediments from settling in the circumferential groove and possibly displacing the fluid required for the gas-tight fluid barrier from the circumferential groove, the invention provides in a further embodiment that the float has a radially outwardly pointing radial approach which extends at least up to the region of the inclination of the peripheral edge of the radially outer peripheral wall portion. Sediments or solid particles flowing or falling downwardly from the exhaust gas upstream in the direction of the levitation body can not enter the circumferential groove because the radial extension covers and thus shields the circumferential groove. This ensures that only fluid is present in the circumferential groove to form a fluid sealing seat.

In order to clean the backflow barrier, which is difficult to access from the outside, it is provided in a further development of the invention that the tubular body has at least one passage opening which is arranged and formed downstream of the peripheral edge of the radially outer peripheral wall section. As a result, for example, the introduction of a water hose or water alone is possible to clean the interior above the float during maintenance. In operation, the passage opening is closed by means of a corresponding closure means, so that no exhaust gases can escape.

The production of such a non-return valve is usually carried out by means of a plastic injection molding process, which, however, reaches its limits with complex shaping. In order to be able to use such a cost-effective and efficient production process in the non-return valve according to the invention, the invention provides in a further development that a pipe element and an insertable into the pipe element and on the Pipe element demountable attachable support member forming the tubular body. Accordingly, the tubular body is formed at least in two parts. As a result, a cost-effective production of the tubular element and the carrier element attachable thereto in separate manufacturing steps is possible.

In order to attach the carrier element to the pipe element removable, it is advantageous if the pipe element and the support element are each formed as a double-walled pipe sections, wherein a respective pipe section has an outer pipe section and a coaxial with the outer pipe section arranged inner pipe section, and wherein the respective pipe section further closed by a the outer tube section and the inner tube section connecting wall portion end. According to the invention, the diameters of the outer and inner pipe sections of the pipe element are made larger than the diameters of the outer and inner pipe sections of the support element, so that the inner pipe section of the pipe element can be introduced between the outer pipe section and the inner pipe section of the support element. By joining the double-walled pipe sections a channel system is formed, which can be used advantageously.

With regard to irrigation of the circumferential groove by accumulated fluid in the tubular body, it is also advantageous if at least the outer tube section of the carrier element has a greater axial length than the inner tube section of the carrier element. This implies that the peripheral edge of the inner tube portion is located upstream below the peripheral edge of the outer tube portion of the carrier member so that fluid accumulated between the outer tube portion and the inner tube portion of the carrier member can flow over the peripheral edge of the inner tube portion into the circumferential groove.

In a further development of the invention is then provided that the radially outer peripheral wall portion of an axial portion of the inner tube portion and the radially inner peripheral wall portion of a on the inner tube portion of Support member formed and radially inwardly directed wall portion is formed. In this way, a part of the inner pipe section can be used at the same time as a peripheral wall section of the circumferential groove at low cost and in a structurally simple manner.

In order to take advantage of the two-part design of the tubular body, the invention is provided in a further embodiment that in the assembled state of Rückströmsperre the double-walled insert element is open downstream and the double-walled tubular element is open upstream, wherein the inner tube portion of the tubular element and the double-walled support element in assembled state together form a U-shaped siphon by the inner tube portion of the tubular element between the outer tube portion and the inner tube portion of the support member is arranged. Accordingly, a further circumferential groove is formed by the carrier element, which connects radially outwardly to the circumferential groove, in which the axial extension of the float protrudes when resting on the valve seat. Due to the fact that the inner tube section of the tube element is preferably arranged coaxially between the inner and outer tube sections of the carrier element, a gastight seal is also achieved in this region of the return flow barrier with sufficient existing fluid or accumulated condensate within the double-walled tube section of the carrier element.

In a further embodiment of the invention, it is then provided that the support element of the peripheral edge of the inner pipe section ends upstream of the peripheral edge of the outer pipe section. This measure also serves to allow accumulated fluid to flow over the peripheral edge of the inner tube section into the circumferential groove.

In order to dissipate excess accumulated fluid from the tubular body, the invention provides in an advantageous development that between the outer tube portion of the support member and the outer tube portion of the tubular element, a flow channel for fluid is formed.

In an alternative embodiment of an integrally formed tubular body, it is provided according to the invention that the tubular body has at least one passage opening arranged upstream of the circumferential groove, wherein the at least one passage opening is connected to a siphon which is arranged outside the tube body and can be attached to it in a detachable manner, into the fluid from the interior of the tubular body, and wherein the siphon is connected to the at least one passage opening through which fluid can be discharged from the siphon. As a result, the U-shaped and formed inside the Rückströmsperre siphon is dispensable and is replaced by the external siphon. During maintenance, this external siphon is easily removable from the pipe body and can be cleaned without the Rückströmsperre and thus a part of the exhaust system would have to be dismantled. In addition, water can be introduced through the passage opening and / or the passage opening for cleaning the interior area of the non-return valve and for flushing the siphon. The arranged outside the tubular body siphon prevented as the U-shaped trap a backflow of exhaust gas in areas below the float.

In a further embodiment of the invention, it is provided that the float has an annular portion and at least one plate-shaped portion, each next-larger portion forms an additional valve seat for the next-smaller portion. Compared with known one-stage backflow, it is thus possible in particular in combustion devices with large exhaust gas flows, the opening cross section of small exhaust gas streams, such as those occur in partial load operation, adapt and provide in full-load operation additional passages for the resulting very large amounts of exhaust gas.

In order to transfer the inventive concept of a fluid sealing seat also on the inner sections is provided in a further embodiment of the invention, that the peripheral edge of at least a next-smaller portion a radially outwardly beyond the additional valve seat protruding and upstream directed additional axial approach includes, which is in resting on the next-smaller portion on the additional valve seat of the next-larger subsection in a formed on the next-larger subsection additional circumferential groove extends.

According to a further advantageous feature of the invention, it is provided that each next-smaller subsection and the next-larger subsection telescopically engage and have cooperating stops for limiting the lifting movement of the next-smaller subsection, each next-smaller subsection of the floating body having a central , upstream approach, which engages in a central sleeve of the next-larger subsection, and wherein the sleeve forms the upstream approach of the next-larger subsection. Due to the sleeve design, two functions can be integrated in one approach of a subsection. The outside serves for own leadership, whereas the inside serves to guide the next smaller section. This greatly simplifies the structure of the guides.

Finally, it is provided in an embodiment of the invention that the sleeve of the largest part of the floating body is guided in a guide, which are formed or supported by radially inwardly projecting webs of the tubular body. Again, it is advantageous to limit the maximum lift-off of the largest section, for example by means of a stop in the form of a radial thickening at the upstream end of the sleeve.

It is understood that the features mentioned above and those yet to be explained can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention. The scope of the invention is defined only by the claims.

• Figur 1 eine zum Teil geschnittene Perspektivansicht einer erfindungsgemäßen Rückströmsperre,
• Figur 2 einen äußeren, ringförmig ausgebildeten Teilabschnitt eines Schwebekörpers in Perspektivdarstellung,
• Figur 3 den äußeren, ringförmig ausgebildeten Teilabschnitt des Schwebekörpers aus Figur 2a in Schnittansicht,
• Figur 4 einen inneren, tellerförmig ausgebildeten Teilabschnitt des Schwebekörpers in Perspektivansicht,
• Figur 5 ein Rohrelement in perspektivischer Ansicht und in einer teilweisen Schnittansicht,
• Figur 6 ein Trägerelement in perspektivischer Ansicht und in einer teilweisen Schnittansicht,
• Figur 7 ein muffenförmiges Verbindungselement,
• Figur 8 ein in das muffenförmige Verbindungselement einsetzbares Dichtungselement,
• Figur 9 die Position des Schwebekörpers bei Teillast-Betrieb,
• Figur 10 die Position des Schwebekörpers bei Volllast-Betrieb,
• Figur 11 einen Betriebszustand der Rückströmsperre direkt nach dem Einbau in eine Abgasleitung,
• Figur 12 einen Betriebszustand, bei dem ein U-förmiger Siphon mit einem Fluid gefüllt ist,
• Figur 13 einen Betriebszustand, bei dem der U-förmige Siphon sich in eine Umfangsrinne entwässert,
• Figur 14 einen Betriebszustand, bei dem der U-förmige Siphon sich in einen Ablaufkanal entwässert,
• Figur 15 einen Betriebszustand mit einem stromabwärts vorherrschenden Überdruck,
• Figur 16 einen Betriebszustand, bei dem in der Umfangsrinne kein Fluid enthalten ist,
• Figur 17 eine Weiterbildung der erfindungsgemäßen Rückströmsperre,
• Figur 18 die in Figur 17 dargestellte Weiterbildung in zum Teil geschnittener Ansicht,
• Figur 19 eine Rückströmsperre gemäß einer alternativen Ausgestaltung,
• Figur 20 die in Figur 19 dargestellte Rückströmsperre in zum Teil geschnittener Ansicht und
• Figur 21 eine vergrößerte Ansicht eines Ausschnitts der in den Figuren 19 und 20 dargestellten Rückströmsperre in Schnittansicht.

Further details, features and advantages of the subject matter of the invention will become apparent from the following description in Connection with the drawing, in the example of a preferred embodiment of the invention is shown. In the drawing shows:

• FIG. 1 a partially sectioned perspective view of a Rückströmsperre invention,
• FIG. 2 an outer annular section of a float in perspective view,
• FIG. 3 the outer annular portion of the float out FIG. 2a in sectional view,
• FIG. 4 an inner, dish-shaped section of the float in perspective view,
• FIG. 5 a pipe element in perspective view and in a partial sectional view,
• FIG. 6 a carrier element in perspective view and in a partial sectional view,
• FIG. 7 a sleeve-shaped connecting element,
• FIG. 8 a sealing element which can be inserted into the sleeve-shaped connecting element,
• FIG. 9 the position of the float at part-load operation,
• FIG. 10 the position of the float at full load,
• FIG. 11 an operating state of the non-return valve directly after installation in an exhaust pipe,
• FIG. 12 an operating condition in which a U-shaped siphon is filled with a fluid,
• FIG. 13 an operating condition in which the U-shaped siphon drains into a circumferential trough,
• FIG. 14 an operating condition in which the U-shaped siphon drains into a drainage channel,
• FIG. 15 an operating condition with a downstream prevailing overpressure,
• FIG. 16 an operating condition in which no fluid is contained in the circumferential groove,
• FIG. 17 a development of the non-return valve according to the invention,
• FIG. 18 in the FIG. 17 illustrated development in a partially sectioned view,
• FIG. 19 a non-return valve according to an alternative embodiment,
• FIG. 20 in the FIG. 19 illustrated Rückströmsperre in partially sectioned view and
• FIG. 21 an enlarged view of a section of the in the FIGS. 19 and 20 illustrated Rückströmsperre in sectional view.

Hereinafter, the Rückströmsperre invention 1 an exhaust pipe of a combustion device with respect to the FIGS. 1 to 16 described. In the FIG. 1 in a partially sectioned perspective view shown backflow preventer 1 has a tubular body 2, which is installed in a vertical portion of the flowed through from bottom to top exhaust pipe. Inside the tubular body 2, a valve seat 3 is formed, on which a floating body 4 rests in its closed position. By vertically or from bottom to top flowing exhaust gas of the float 4 can be lifted from the valve seat 3 downstream. Furthermore, at least one downstream circumferential groove 5 is arranged inside the tubular body 2. The circumferential groove 5 is bounded by a radially inner peripheral wall portion 6 and a radially outer peripheral wall portion 7, wherein the two peripheral wall portion 6 and 7 are formed inside the tubular body 2. The peripheral edge 8 of the radially inner peripheral wall portion 6 in this case forms the valve seat 3 for the float 4, as from FIG. 6 is apparent.

The float 4 includes one in the FIGS. 2 and 3 illustrated outer section 9, which is annular, and an in FIG. 4 illustrated inner portion 10, which is plate-shaped. In the closed position of the float 4 after FIG. 1 rests the outer portion 9 of the float 4 on the valve seat 3, which is provided inside the tubular body 2. In addition, the outer portion 9 forms an additional valve seat 11 (see FIG. 3 ), on which the inner section 10 in the closed position rests. If the associated combustion device is operated in part-load operation, then the inner or next-smaller subsection 10 lifts off from its additional valve seat 11 and releases the exhaust line partially or partially, as shown in FIG FIG. 9 is shown as an example for the part-load operation. The position of the inner subsection 10 adjusts itself to the amount of exhaust gas to be discharged. If the exhaust gas continues to increase, as is the case during full-load operation of the combustion device, the outer subsection 9 of the float 4 also leaves its valve seat 3 and releases the maximum passage cross-section of the non-return valve 1, as is shown by way of example in FIG FIG. 10 is shown. From the FIGS. 2 to 4 It can also be seen that the inner portion 10 of the floating body 3 carries an upstream, that is downwardly directed approach 12 which engages telescopically in a likewise upstream approach 13 of the outer portion 9. The projection 13 of the outer portion 9 is connected via radial webs 14 (see FIGS. 2 and 3 ) is connected to the outer, annular portion 9. The sleeve-shaped projection 13 of the outer portion 9 forms in its upper part a guide 15 for the peg-shaped projection 12 of the inner portion 10. The neck 12 of the inner portion 10 carries at its lower end a trained as a thickening stop 16, with a complementary stop in the interior of the projection 13 of the outer portion 9 cooperates. In this way, the upward movement of the inner subsection 10 relative to the outer subsection 9 is limited. The sleeve-shaped projection 13 of the outer portion 9 of the float 4 is in turn guided in a guide 17 which is supported by radially inwardly projecting webs 18 of the tubular body 2 (see FIG. 6 ). The projection 13 of the outer portion 9 also carries at its lower end a trained as a thickening stop 19, which limits the upward movement of the outer portion 9 relative to the tubular body 2. The non-return valve 1 with the two-stage floating body 4 is therefore suitable for combustion facilities high power with simultaneous mastering of the partial load range. However, the person skilled in the art will recognize that the float 4 can also be embodied in one piece or with more than two parts.

At the backflow stop 1 after FIG. 1 the tubular body 2 is designed in several parts and comprises a tubular element 20 and a carrier element 21, which is closer in the FIGS. 5 and 6 are shown. The support member 21 is detachably attachable to the tubular member 20 and inserted or inserted into this. For this purpose, the support member 21 a plurality of latching projections 22 which are formed uniformly spaced on the outer periphery, as in FIG. 6 can be seen. As further in FIG. 5 can be seen, the tube member 20 a plurality of complementary to the latching projections 22 formed Einrastausnehmungen 23, in which engage the Einrastvorsprünge 22 during assembly of tube member 20 and support member 21 to the tubular body 2.

Such as the Figures 5 . 9 and 10 can be seen, the tube member 20 has a double-walled pipe section, which is formed by an outer pipe section 24 and an inner pipe section 25. The double-walled pipe section of the tubular element 20 is closed by a wall section 26 which connects the outer pipe section 24 and the inner pipe section 25 and extends obliquely. In the assembled state of tubular element 20 and support member 21, the double-walled pipe section of the tubular element 20 is open upstream or downwards, wherein the outer pipe section 24 extends further upstream than inner pipe section 25. At the upper end of the tubular element 20 is the attachment of a sleeve-shaped connecting element 39, that in detail FIG. 7 is shown, provided for connection to the exhaust pipe, wherein an insertable into the sleeve-shaped connecting element 39 sealing element 40, which in FIG. 8 is shown in more detail, is provided for sealing.

The support member 21 also includes a double-walled pipe section with an outer pipe section 27 and an inner pipe section 28, wherein the double-walled Pipe section is closed at one longitudinal end by means of a wall section 29 connecting the outer pipe section 27 and the inner pipe section 28. In the assembled state of tubular element 20 and support member 21 of the double-walled pipe section of the support member 21 is open at the top and downstream, whereas the double-walled pipe section of the tubular member 20 is open upstream or down. In the support element 21, the outer pipe section 27 has a greater axial length than the inner pipe section 28, so that the peripheral edge 30 of the outer pipe section 27 is disposed below or upstream of the peripheral edge 31 of the inner pipe section 28.

The circumferential groove 5 is thus part of the carrier element 21, wherein the radially outer peripheral wall portion 7 is formed by an axial portion of the inner tube portion 27 of the support member 21, whereas the radially inner peripheral wall portion 6 of a formed on the inner tube portion 27 of the support member 21 and radially inwardly directed Wall section 32 is formed. The peripheral edge 33 of the integrally formed on the inner tube portion 27 of the support member 21 wall portion 32 is located above or upstream of both the peripheral edge 30 of the outer tube portion 27 and the peripheral edge 31 of the inner tube portion 28 of the support member 21. Thus lies in the support member 21 of the peripheral edge 30 of the outer tube section 28 downstream The peripheral edge 31 of the inner pipe section 28 and upstream of the peripheral edge 33 of the wall portion 32 and the peripheral wall portion 6. The radially inwardly projecting webs 18 are formed on the wall portion 32 and to the radially inner peripheral wall portion 7, the sleeve-shaped guide 17 for the approach 13 of the outer portion 9 of the float 4 wear.

In the assembled state of the tubular body 2 of the inner tube portion 25 of the tubular element 20 and the double-walled support member 21 form a U-shaped siphon 34, the in FIG. 11 is shown in the form of the dashed line. The U-shaped siphon is formed by the inner tube portion 25 of the tubular element 20 between the outer tube portion 27 and the Inner tube portion 28 of the support member 21 is arranged substantially coaxially, wherein between the peripheral edge or the free end of the inner tube portion 25 of the tubular element and the wall portion 29 of the support member 21, a gap is present. The U-shaped siphon 34 should always be filled with a fluid during operation of the backflow lock 1, so that the passage of exhaust gases through the channel or conduit system of the U-shaped siphon 34 is difficult or not possible. At the same time, however, condensate originating from the exhaust gas can flow away through the U-shaped siphon 34, so that proper functioning of the non-return valve 1 is ensured. The exact operation of the U-shaped siphon 34 will be discussed in detail below. It should be noted that the two-piece tubular body 2 can of course also be formed in one piece or in one piece, however, for the sake of ease of manufacture at least two-part design is desirable to manufacture the complex, siphon-like wall system.

With reference to the figures, the peripheral edge of the annular outer portion 9 of the floating body 4 has an axial projection 35 which projects radially beyond the radially inner peripheral wall portion 6 and the wall portion 32, respectively. As in particular in the FIG. 1 can be seen, the upstream or vertically downwardly facing axial extension 35 extends when resting the outer portion 9 of the float 4 on the valve seat 3 in the axial direction in the circumferential groove 5 inside. In addition, the outer portion 9 of the floating body 4 comprises a radially outwardly facing radial projection 36 which attaches to the axial extension 35. The radial approach 36 extends to the peripheral edge 31 of the inner tube 28 of the support member 21. As in particular in the FIGS. 1 and 9 to 16 can be seen, the radial projection 36 of the outer portion 9 of the floating body 4 extends at least into the region of a formed on the peripheral edge 33 of the radially inner peripheral wall 6 slope 37. The slope 37 extends radially outwards and upstream, so that vertically downwards or upstream of the exhaust gas separated condensate is not in the circumferential groove 5, but in the radially outwardly adjoining the U-shaped siphon 34 is derived or flows out there.

In the FIGS. 11 to 16 are sections of a portion of the check valve 1 shown, in which the combustion device is not in operation and the float 4 is in each case in the closed position and the outer portion 9 rests on the valve seat 3.

The representation in FIG. 11 corresponds to an operating state after installation of the non-return valve 1 in an exhaust pipe of a combustion device. Here, the circumferential groove 5 and formed by the tubular member 20 and the support member 21 U-shaped siphon 34 is free of any fluid and condensate. In the illustrated closed position of the float 4, the inner section 10 of the floating body 4 seals mechanically with contact on the additional valve seat 11 of the outer section 9 of the floating body 4. In addition, the outer portion 9 of the floating body 4 seals mechanically via its contact surfaces on the valve seat 3. Due to the non-existent fluid in the U-shaped siphon 34, this has a leakage, so that exhaust gases can flow to vertically located below the float 4 areas.

In order to prevent the leakage present in the region of the U-shaped siphon 34, the U-shaped siphon 34 formed by the tube element 20 and the carrier element 21 is filled with a predetermined quantity of fluid 38 before the combustion device or the backflow barrier 1 is put into operation. This operating state is in FIG. 12 illustrated, wherein the amount of fluid 38 must be at least sized so that a passage of exhaust gas through the U-shaped siphon 34 is no longer possible, ie the amount of fluid 38 must at least up to the free longitudinal end of the inner tube portion 25 of the tubular element 20th pass. By the filling of fluid 38, a fluid barrier is then achieved in the U-shaped siphon 34, which prevents the passage of exhaust gas to lying below the floating body 4 areas of the backflow 1, wherein the outer portion 9 and the inner portion 10 of the float 4 after as mechanically seal and prevent exhaust gases from reaching upstream.

The rise height of the fluid 38 in the U-shaped siphon 34 is limited by the structural design of the support member 21. The rise height of the fluid 38 within the U-shaped siphon 34 is limited by the peripheral edge 30 of the outer tube section 27 and the peripheral edge 31 of the inner tube section 28. Due to condensate originating from the exhaust gas that has flowed through the backflow preventer 1, the level of the fluid 38 in the U-shaped siphon 34 can continue to exceed that shown in FIG FIG. 12 increase in height. If the level of the fluid 38 rises above the peripheral edge 31 of the inner tube section 28 of the carrier element 21, then the mixture of fluid and condensate flows over the peripheral edge 31 into the circumferential channel 5, which leads to its filling in the previously fluid-free circumferential channel 5, as in FIG. 13 is apparent. Thus, the U-shaped siphon 34 can provide for irrigation of the circumferential groove 5. In the closing position of the floating body 4, the axial extension 35 of the outer section 9 emerges into the mixture of fluid and condensate, which is now also in the circumferential channel 5. In this way, in addition to the mechanical seal by the resting of the outer portion 9 on the valve seat 3 additionally a fluid seal, which is effected by the interaction of fluid and axial extension 35. Thus, when the outer subsection 9 of the floating body 4 rests on the valve seat 3, the fluid 38 located in the circumferential groove 5 together with the axial extension 35 forms a gas-tight fluid barrier. Furthermore, no heavy sediments from the exhaust gas get into the circumferential groove 5, because the outer subsection 9 of the floating body 4 has the radial extension 36, which covers the circumferential groove 5. Instead, heavy sediments are directed into the U-shaped siphon 34, where they can deposit on the wall portion 29. The radial projection 36 of the float 4 thus forms a protection against originating from the exhaust stream sediments, which can deposit and accumulate only in the portion of the U-shaped siphon 34. In the FIG. 13 shown rise height of the mixture Fluid 38 and condensate represents the maximum achievable rise height in the circumferential groove 5 and the U-shaped siphon 34.

If the level of the mixture of fluid 38 and condensate continues to increase, the system drains over the U-shaped siphon 34, as in FIG FIG. 14 is shown. In this case, the mixture flows over the peripheral edge 30 of the outer tube section 27 of the carrier element 21. Conveniently, the peripheral edge 30 of the outer tube portion 27 is located upstream below the radial shoulder 36, but downstream above the peripheral edge 31 of the inner tube portion 28 of the support member 21 so that the mixture of fluid 38 and condensate can not rise above the radial extension 36, whereby the outer portion 9 Float 4 could be prevented from ascending. A further increase in the fluid level therefore merely results in the mixture of fluid 38 and condensate flowing away via a drainage channel 41 formed between the outer tube 27 of the carrier element 21 and the outer tube 24 of the tubular element 20.

In FIG. 15 an operating state is shown, which corresponds to the in FIG. 14 can connect shown operating state. At the in FIG. 15 shown operating state, the float 4 is again in the closed position, downstream of the backflow preventer 1 there is an overpressure, which acts on the float 4 and the outer portion 9 presses on the valve seat 3. This overpressure also causes the fluid 38 located in the circumferential groove 5 and in the U-shaped siphon 34 to be forced downwardly upstream. In this case, the fluid 38 located in the circumferential groove 5 can reach at most only up to the mechanical sealing seat, which is formed by the float 4 and the valve seat 3. Furthermore, the fluid 38 located in the channel formed between the inner pipe section 28 of the carrier element 21 and the inner pipe section 25 of the pipe element 20 is pushed downwards so that the fluid 38 flows through the discharge channel 41 between the outer pipe section 27 of the carrier element 21 and the outer pipe section 24 of the tubular element 20 is formed, can flow. In the FIG. 15 shown amount of fluid 38, which is located in the circumferential groove 5, is in this Overpressure operating condition in which a low overpressure prevails, sufficient to cause the fluid sealing effect between the outer portion 9 of the float 4 and the fluid 38, since a lower portion of the axial extension 35 is still immersed in the fluid 38.

In FIG. 16 an accident-like operating state is shown, in which the circumferential groove 5 has no fluid and is dried out. In this case, however, a mechanical seal still takes place through the contact between the outer section 9 of the float 4 and the valve seat 3. Due to the low fluid level or the non-existent sealing water level in the circumferential groove 5 an absolute gas tightness is guaranteed only up to a certain pressure. If this excess pressure is exceeded, the system seals mechanically over the contact surfaces on. This accident, in which the combustion device is stationary and condensate or fluid has evaporated in the circumferential groove 5, with the in the FIG. 12 shown operating state comparable, so that reference is made to the comments on this operating condition.

A development of the backflow barrier 1 described above is in the FIGS. 17 and 18 shown. In this development, a passage opening 42 is formed in the wall of the tubular body 2, to the outside of the wall of the tubular body 2, a tubular nozzle 43 attaches. The nozzle 43 may in this case be designed, for example, as a connection for a water hose. It is also conceivable, however, to provide only the through-opening 42 instead of the connecting piece 43, through which a water hose can be introduced into the interior of the tubular body 2 for maintenance and cleaning purposes. As a result, water can be passed for cleaning above the float 4 or directly into the U-shaped siphon 34. Dirt particles are flushed out during cleaning due to the large volume of water through the U-shaped siphon 34 and then via the drainage channel 41. In operation, the passage opening 42 or the nozzle 43 is closed by means of a cap, not shown.

The in the FIGS. 1 to 17 described tubular body 2 is designed to form the internally arranged and U-shaped siphon 34 by means of the tubular element 20 and support member 21 in two parts. In contrast, for in the FIGS. 19 to 21 illustrated backflow preventer 1 a one-piece design of the tubular body 2 is provided, which does not provide a trained inside the tubular body 2 siphon. In order to dissipate excess fluid from the interior of the tubular body 2, a passage opening 44 is provided in the wall of the tubular body 2, which opens substantially at the level of the peripheral edge 30 of the radially outer peripheral wall portion 7 and extends downstream. Connected to the passage opening 44 is a pipe section 45 which leads to a siphoning device 46 arranged outside the pipe body 2. This externally arranged siphon device or this external siphon 46 is formed in two parts and comprises a first component 47 and a second component 48. Both components 47 and 48 are formed in the manner of a two-part container and connectable to each other in the middle. In this case, the pipe section 45 is connected to the first component 47. Furthermore, this pipe section 45 extends within the two assembled components 47, 48 to just before the bottom wall of the cup-shaped second member 48. Laterally from the first member 47 leads another pipe section 49 from the siphon 46 back to the backflow valve 1. This pipe section 49 opens into a Passage opening 50, which is formed in the wall of the tubular body 2 upstream, that is below, of the floating body 4. Excess fluid or even dirt particles can be removed from the interior of the tubular body 2 and passed into the siphon 46 through the passage opening 44. For this purpose, the pipe section 45 is slightly inclined and designed sloping in the direction of the siphon 46. The fluid and dirt particles conducted into the siphon 46 collect in the pot-shaped second component 48. As soon as the level height of the accumulated fluid within the siphon 46 reaches the height of the passage opening 50, the fluid flows over the pipe section 49 in the interior of the Rückströmsperre 1 back, which is indicated by the arrows. Inside the backflow barrier 1, the returned fluid is then passed to, for example, a condensate drainage system and discharged therefrom. The principle of arranged outside the tubular body 2 siphon 46 is identical to that in the FIGS. 11 to 16 described mode of action. As long as the free end of extending to near the bottom wall of the cup-shaped member 47 pipe section 45 is immersed in fluid, which can be done, for example, before startup of the Rückströmsperre 1 by appropriate filling, no downstream of the float 4 existing exhaust gas in the area below the float 4 arrive because the siphon 46 prevents gas passage due to its filling.

The invention was made against the background that the production of large floating bodies in an injection molding process causes great difficulties in order to comply with certain tolerances of the individual components. For injection molded components of large dimensions, these always show a certain delay after the cooling process. This delay causes the mechanical seal between valve seat and float can be insufficient, since a continuous and necessary for the sealing contact of the components is not guaranteed due to the delay. Since components for such a field of application are additionally exposed to massive temperature loads by the flowing exhaust gas, these loads can additionally cause a material distortion, which can increase the leakage. The invention makes use of the property of fluids, since they always adapt to the contours of the components. For this reason, in addition to the known mechanical seal between the float and the valve seat, a fluid seal or a fluid sealing seat was additionally provided. Thus, with the help of the invention even a relatively heavily warped float 4 almost perfectly seal, as long as its axial extension 35 is immersed in a fluid 38 located in the circumferential groove 5 and the fluid level is sufficiently high. To remove deposits from To prevent dirt particles within the circumferential groove 5, which could adversely affect the fluid seal, the float in addition to the circumferential groove 5 radially outwardly projecting radial shoulder 36 on. Thus, in the provided inside the tubular body 2 U-shaped siphon 34 dirt particles are passed directly into this and can be rinsed, for example, during maintenance by water is introduced through the passage opening 44 for flushing in the tubular body 2. For external or externally mounted on the tubular body 2 siphon 46 this is disassembled for maintenance and cleaning purposes of the tubular body 2 in a simple manner and cleaned. Thus, in addition to the fluid barrier formed in the circumferential groove 5 by a fluid and the axial extension 35, the invention also comprises a siphon 34 or 46 which is arranged and formed radially outwardly around the circumferential groove 5 and inside the tube body or outside the tube body 2.

The inner section 10 of the float 4 is purely optional, with this section 10 only mechanically seals in the illustrated embodiment. In a modification of the illustrated embodiment, the peripheral edge of each inner or next-smaller portion 10 may have a radially outwardly projecting beyond the additional valve seat 11 and upstream directed additional axial approach, which is at rest of the next-smaller portion 10 on the addition Valve seat 11 of the outer or next-larger portion 9 extends into a formed on the next-larger portion 9 additional circumferential groove inside. However, due to its smaller dimensions, the inner section 10 has only minor leaks at the mechanical sealing seat, whereby the component distortion also tends to be low due to the relatively small dimensions, so that a fluid sealing seat for this area can be dispensed with. In principle, however, it is also conceivable for inner sections, a fluid seal, as well as between the outer portion 9 and the circumferential groove 5 by means of the fluid 38 and the Axialansatz 36 is provided to use. It is also conceivable, however, for the presented invention to be used in applications with a one-piece float.

Of course, the invention described above is not limited to the described and illustrated embodiment. It is conceivable, for example, an outer portion of the float without radial approach, as this provides no direct contribution to the fluid seal. Numerous modifications which are obvious to a person skilled in the art according to the intended application can be made to the embodiment shown in the drawing, without departing from the scope of the invention. It belongs to the invention, all that which is contained in the description and / or shown in the drawing, including what, in deviation from the concrete embodiment obvious to those skilled.

Claims (14)

1. A check valve (1) for an exhaust gas line of an incineration plant, wherein the check valve (1) comprises a tubular body (2) which can be installed in a vertical section of the exhaust gas line, a float body (4), a valve seat (3) constituted inside the tubular body (2) for the one float body (4) which can be lifted from the valve seat (3) by gas flowing vertically upwards, and at least one peripheral groove (5) which is open upstream and disposed radially inside the tubular body (2), said peripheral groove being limited by a radially inner peripheral wall section (6) and a radially outer peripheral wall section (7), wherein the radially inner peripheral wall section (6) and the radially outer peripheral wall section (7) are constituted inside the tubular body (2) and the peripheral edge (8) of the radially inner peripheral wall section (6) forms the valve seat (3) for the at least one float body (4), characterized in that the peripheral edge of the at least one float body (4) projects radially beyond the radially inner peripheral wall section (6) and comprises an axial extension (35) pointing upstream, which extends in the axial direction into the peripheral groove (5) when the at least one float body (4) sits on the valve seat (3), wherein, by means of a fluid (38) present in the peripheral groove (5), the axial extension (35) together with the fluid (38) forms a gas-tight fluid barrier when the float body (4) sits on the valve seat (3).
2. The check valve (1) according to claim 1, characterized in that the peripheral edge (31) of the radially outer peripheral wall section (7) comprises at least in sections a bevel (37) running radially outwards and upstream.
3. The check valve (1) according to claim 2, characterized in that the float body (4) comprises a radially outwardly pointing radial extension (36), which extends at least into the region of the bevel (37) of the peripheral edge (31) of the radially outer peripheral wall section (7).
4. The check valve (1) according to any one of the preceding claims, characterized in that the tubular body (2) comprises at least one through-opening (42; 44), which is disposed and constituted downstream of the peripheral edge (30) of the radially outer peripheral wall section (7).
5. The check valve (1) according to any one of the preceding claims, characterized in that a tubular element (20) and a carrier element (21) which can be introduced into the tubular element (20) and fitted detachably to the tubular element (20) constitute the tubular body (2).
6. The check valve (1) according to claim 5, characterized in that the tubular element (20) and the carrier element (21) are each constituted as double-walled tubular sections, wherein a given tubular section comprises an outer tubular section (24; 27) and an inner tubular section (25; 28) disposed coaxially with respect to the outer tubular section (24; 27), and wherein the given tubular section is also closed at the end by a wall section (26; 29) connecting the outer tubular section (24; 27) and the inner tubular section (25; 28).
7. The check valve (1) according to claim 6, characterized in that at least the outer tubular section (27) of the carrier element (21) has a greater axial length than the inner tubular section (28) of the carrier element (21).
8. The check valve (1) according to claim 6 or 7, characterized in that the radially outer peripheral wall section (7) is constituted by an axial section of the inner tubular section (28) of the carrier element (21) and the radially inner peripheral wall section (6) is constituted by a radially inwardly directed wall section (32) integrally moulded on the inner tubular section (28) of the carrier element (21).
9. The check valve (1) according to any one of claims 6 to 8, characterized in that, in the assembled state of the check valve (1), the carrier element (21) constituted double-walled is open downstream and the tubular element (20) constituted double-walled is open upstream, wherein the inner tubular section (25) of the tubular element (20) and the double-walled carrier element (21) constitute a U-shaped siphon (34) by the fact that the inner tubular section (25) of the tubular element (20) is disposed, preferably coaxially, between the outer tubular section (27) and the inner tubular section (28) of the carrier element (21).
10. The check valve (1) according to any one of claims 6 to 9, characterized in that the peripheral edge (31) of the inner tubular section (28) terminates upstream of the peripheral edge (30) of the outer tubular section (27) in the case of the carrier element (21).
11. The check valve (1) according to any one of claims 6 to 10, characterized in that a drainage channel (41) for excess fluid is constituted between the outer tubular section (27) of the carrier element (21) and the outer tubular section (24) of the tubular element (20).
12. The check valve (1) according to claim 4, characterized in that the tubular body (2) comprises at least one through-opening (50) disposed upstream of the peripheral groove (5), wherein the at least one through-opening (44) is connected to a siphon (46) which is disposed outside the tubular body (2) and can be fitted detachably to the latter, into which siphon fluid can drain away out of the interior of the tubular body (2), and wherein the siphon (46) is connected to the at least one through-opening (50), through which fluid can be carried away out of the siphon (46).
13. The check valve (1) according to any one of the preceding claims, characterized in that the float body (4) comprises a partial section (9) constituted ringshaped and at least one partial section (10) constituted saucer-shaped, wherein each next larger partial section (9) constitutes an additional valve seat (11) for the next smaller partial section (10).
14. The check valve (1) according to claim 13, characterized in that the peripheral edge of at least one next smaller partial section (10) comprises an additional axial extension projecting radially outwards beyond the additional valve seat (11) and directed upstream, said additional axial extension extending into an additional peripheral groove constituted on the next larger partial section (9) when the next smaller partial section (10) sits on the additional valve seat (11) of the next larger partial section (9).

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