Patent Description:
Various facilities, such as factories and offices, which use steam as a heat source via heat exchangers use steam traps to automatically discharge, to outside of a steam transport piping system, a drain liquid (condensate resulting from condensation of steam) produced in pieces of steam using equipment and the steam transport piping system between these pieces of equipment.

This is to ensure appropriate temperature conditions in the pieces of steam using equipment, such as heating machines, drying machines, and heaters, which use high-temperature and high-pressure steam obtained with a boiler at heat exchange units and in a steam transport piping system connecting the boiler and the pieces of steam using equipment. If, for example, a drain liquid stays in a piece of steam using equipment, the heating efficiency of that piece of equipment drops, which significantly lowers its productivity. Moreover, droplets of the drain liquid cause heating unevenness, which may be a cause of deterioration in product quality and impair the stable operation of the factory or the like. Also, if a drain liquid stays within the steam transport piping system, it may be a cause of an extremely dangerous steam hammer and impair the safe operation of the factory. This steam hammer refers to a phenomenon in which, for example, a drain liquid staying within the steam transport piping system forms a large mass while being pushed by steam to flow, and collides with a curved portion of a pipe or a valve. The steam hammer refers alternatively to a phenomenon in which, when a drain liquid staying within the steam transport piping system comes into contact with steam, the steam gets condensed at a stretch, so that the volume of the steam reduces to zero and the drain liquid rushes to and collides with where a vacuum state is locally formed.

There are various types of steam traps. Examples include mechanical engineering-based mechanical steam traps (bucket type and float type), thermostatic steam traps (bimetal type and bellows type), and thermodynamic steam traps (disc type) as steam traps having a movable part. For example, Patent Literature <NUM> discloses an example of the float-type steam trap.

Also, as steam traps having no particular movable part, there are nozzle-type steam traps as represented by orifice nozzle-type, Venturi nozzle-type, and tunnel-structured resistance tube-type steam traps (see Patent Literature <NUM>, for example). These nozzle-type steam traps are called fluidics-based steam traps and utilize the nature that, when passing through a small passage, water (liquid water) is lower in kinetic viscosity than steam and water is approximately <NUM> times higher in fluidity than steam.

Patent Literature <NUM> discloses a flange <NUM> with a central flow hole <NUM> therethrough and a pressure reducer <NUM> that is secured to the flange <NUM>. The pressure reducer <NUM> is adapted for use along a pipe line <NUM>. The flow hole <NUM> is aligned with an inlet <NUM> of an inner annular sleeve <NUM> of the pressure reducer <NUM>. Pressurized fluid flow from an upstream side of the pipe line <NUM> flows through the flow hole <NUM>, through the pressure reducer <NUM>, and to a downstream side of the pressure reducer <NUM>.

Here, since steam traps are used for pipes through which high-temperature and high-pressure steam flows, various improvements to withstand that environment have been proposed, and some of those have already been in practical use. Generally, the materials of constituent members of steam traps are selected or the shapes of contact portions of their movable parts are devised so as to enhance their durability and thus extend their service lives. However, in recent years, steam traps are being used in a wider range of locations and environments. For example, steam traps are being used for pipes through which higher-pressure steam flows. Thus, there is an even higher demand for extending the service lives of steam traps.

An object of the present invention is to provide a configuration capable of contributing to extending the service life of a steam trap.

An aspect of an embodiment of the present invention is exemplarily represented by a pressure reduction mechanism including a pressure reduction part and being to be provided upstream of a steam trap so as to reduce a pressure of a fluid to be supplied into the steam trap.

The pressure reduction part includes a flow-passage narrowing portion, the flow-passage narrowing portion defining and forming a hole extending in a flow direction and having such a dimension as to always permit a free flow of steam therethrough.

Preferably, the flow-passage narrowing portion has a substantially flat surface facing an upstream side in the flow direction. In this case, the flow-passage narrowing portion is advantageously formed such that the hole is open on the surface and the hole has a cross-sectional area that is substantially constant in the flow direction. Alternatively, the flow-passage narrowing portion may be formed such that the hole is open on the surface and the hole becomes wider from the surface toward a downstream side in the flow direction.

Preferably, the flow-passage narrowing portion includes a flat plate-shaped portion having the hole. This flat plate-shaped portion advantageously extends substantially perpendicularly to the flow direction.

Preferably, the above pressure reduction mechanism includes a plurality of the flow-passage narrowing portions, and the plurality of flow-passage narrowing portions are disposed to be spaced in the flow direction. In this case, the hole in each of the plurality of flow-passage narrowing portions is advantageously disposed to be offset from the hole in an adjacent one of the flow-passage narrowing portions. Note that the plurality of holes in the plurality of flow-passage narrowing portions can also be disposed to be located linearly in the flow direction.

Another aspect of an embodiment of the present invention is exemplarily represented by a steam trap system including the pressure reduction mechanism having any one of the above configurations, and a steam trap disposed downstream of this pressure reduction mechanism. For example, the steam trap is a nozzle-type steam trap.

The above pressure reduction mechanism can contribute to extending the service life of a steam trap.

Pressure reduction mechanisms and steam trap systems including these pressure reduction mechanisms and steam traps according to embodiments of the present invention will be described below with reference to the drawings. A first embodiment will be described first.

A pressure reduction mechanism <NUM> according to the first embodiment is provided upstream of a steam trap <NUM>. In the present embodiment, the pressure reduction mechanism <NUM> is embodied as a pressure reduction device <NUM>. A steam trap system <NUM> illustrated in <FIG> includes the pressure reduction device <NUM>, which includes the pressure reduction mechanism <NUM>, and the steam trap <NUM> disposed downstream thereof. Here, the pressure reduction device <NUM> is connected to a fluid inlet portion 12a of the steam trap <NUM> by a nut <NUM>. However, the pressure reduction device <NUM> and the steam trap <NUM> may be connected by different mechanical means.

Here, the steam trap <NUM> will be briefly described first. The steam trap <NUM> is a nozzle-type steam trap. The steam trap <NUM> has a fluid flow passage 12F extending from the fluid inlet portion 12a to a fluid outlet portion 12b. A nozzle <NUM> is disposed at an intermediate portion of that fluid flow passage 12F. The nozzle <NUM> has a hole 18a and, at the downstream end of the hole 18a, has a nozzle outlet 18b as a drain port through which to discharge a drain liquid. The nozzle outlet 18b communicates with a drain-liquid reservoir <NUM>. A drain-liquid discharge port <NUM> for discharging the drain liquid from the drain-liquid reservoir <NUM> to the outside of the steam trap <NUM> communicates with the drain-liquid reservoir <NUM>. Moreover, in the steam trap <NUM>, a strainer <NUM> including a screen <NUM> is disposed downstream of the fluid inlet portion 12a and upstream of the nozzle <NUM>.

In the steam trap <NUM> having the above configuration, steam and a drain liquid from a pipe through which high-temperature and high-pressure steam flows, for example, enter the flow passage 12F from the fluid inlet portion 12a. Rust and dust in the steam and drain liquid are captured by the screen <NUM>, which has minute meshes. The small hole 18a defined and formed in the nozzle <NUM> is designed to have such a hole size as to let the drain liquid pass through the hole 18a without practically letting the steam pass therethrough, by utilizing the nature that, when passing through a small passage, water (liquid water) is lower in kinetic viscosity than steam and water is higher in fluidity than steam. Accordingly, only the drain liquid is mainly discharged from the nozzle outlet 18b of the nozzle <NUM> into the drain-liquid reservoir <NUM>. The drain liquid in the drain-liquid reservoir <NUM> seals the nozzle <NUM>. This can prevent leakage of the steam. Thus, the steam trap <NUM> practically enables drainage of only the drain liquid. Note that the height difference between the drain port 18b and the drain-liquid discharge port <NUM> in the drain-liquid reservoir <NUM> can be adjusted by turning the steam trap <NUM> itself. Doing so can adjust the amount of the drain liquid to be discharged from the steam trap <NUM> (see Patent Literature <NUM>, for example).

Note that, in <FIG>, the upstream end and the downstream end of the steam trap system <NUM> are connected to respective pipes. Unions <NUM> are used for the connections to those pipes. However, the steam trap system <NUM> may be connected to the pipes by different means. Note that reference sign <NUM> denotes a packing.

Incidentally, the pressure reduction device <NUM> employing the pressure reduction mechanism <NUM> is provided upstream of this steam trap <NUM>. In particular, in the steam trap system <NUM> in <FIG>, the pressure reduction device <NUM> is provided adjacent to the fluid inlet portion 12a of the steam trap <NUM>.

The pressure reduction device <NUM> includes a body 11B in which is defined and formed a flow passage 11F communicating with the fluid flow passage 12F in the steam trap <NUM>. Here, the upstream end of the flow passage 11F communicates smoothly with a pipe as illustrated in <FIG>, and the downstream end of the flow passage 11F communicates smoothly with the fluid flow passage 12F as illustrated in <FIG>. Moreover, a pressure reduction part <NUM> of the pressure reduction mechanism <NUM> is provided in that flow passage 11F. The pressure reduction part <NUM> includes a flow-passage narrowing portion <NUM>. The flow-passage narrowing portion <NUM> defines and forms a hole <NUM> extending in a flow direction FD and having such a dimension as to permit a flow of steam therethrough.

The flow-passage narrowing portion <NUM> is formed to include a flat plate-shaped portion <NUM> having the hole <NUM>. The flat plate-shaped portion <NUM> extends substantially perpendicularly to the flow direction FD. Specifically, the flat plate-shaped portion <NUM> extends substantially perpendicularly to an axis AL of the flow passage 11F extending in the flow direction, and extends to a substantially cylindrical inner wall 11W defining and forming the flow passage 11F.

Here, the flow-passage narrowing portion <NUM> includes the flat plate-shaped portion <NUM>, as mentioned above. Thus, the flow-passage narrowing portion <NUM> has a substantially flat surface 32f facing the upstream side in the flow direction FD (hereinafter, the upstream surface). Note that the flow-passage narrowing portion <NUM> here includes the flat plate-shaped portion <NUM> and therefore also has a substantially flat surface facing the downstream side in the flow direction on the side downstream of the upstream surface 32f.

Moreover, the flow-passage narrowing portion <NUM>, i.e., the flat plate-shaped portion <NUM>, is formed such that the hole <NUM> is open on the upstream surface 32f and the hole <NUM> has a cross-sectional area that is substantially constant in the flow direction FD. Note that, like a pressure reduction device 11A as a modification of the pressure reduction device <NUM> schematically illustrated in <FIG>, the hole <NUM> may be defined and formed to become wider from the upstream surface 32f toward the downstream side in the flow direction FD.

This hole <NUM> is defined and formed to extend in the flow direction and have such a dimension as to permit a flow of steam therethrough. To permit a flow of steam means to permit sufficient passage of not only a drain liquid but also steam. Thus, the hole <NUM> is not designed to expect only a drain liquid to preferentially pass therethrough. Note that the hole <NUM> is positioned substantially at the cross-sectional center to be located on the axis AL of the flow passage 11F, but may be positioned off that center to be offset in the radial direction, for example. In the case where the hole <NUM> is provided off the center, the hole <NUM> is advantageously designed to be located on an upper side in the vertical direction, rather than a lower side, when used. This is to prevent backflow of a drain liquid through the hole <NUM>.

Also, the flow-passage narrowing portion <NUM> defining and forming the hole <NUM> is disposed substantially at the center of the flow passage 11F in the pressure reduction device <NUM> in the flow direction. Accordingly, a space of a sufficient size is formed both upstream and downstream of the flow-passage narrowing portion <NUM>. For example, the inner diameter of the hole <NUM> is designed to be a dimension of approximately <NUM>/<NUM> to approximately <NUM>/<NUM> of the inner diameter of the flow passage 11F upstream and downstream of the hole <NUM>, and is advantageously a dimension of approximately <NUM>/<NUM>, for example. Thus, the hole <NUM> in the flow-passage narrowing portion <NUM> is what is called an orifice.

Since the pressure reduction mechanism <NUM> of the pressure reduction device <NUM> is configured as described above, high-temperature and high-pressure steam is reduced in pressure by passing through the hole <NUM> in the pressure reduction device <NUM>. Thus, the fluid (i.e., the steam and the drain liquid) reduced in pressure is supplied into the steam trap <NUM>. This sufficiently lowers the degree of exposure of the steam trap <NUM> to high-temperature and high-pressure steam and can accordingly extend its service life. As described above, the pressure reduction device <NUM>, i.e., the pressure reduction mechanism <NUM>, can contribute to extending the service life of the steam trap <NUM>.

Next, a second embodiment will be described. A steam trap system according to the second embodiment includes a pressure reduction mechanism <NUM> and a steam trap <NUM> provided downstream thereof. The steam trap <NUM> is the one already described. Thus, the pressure reduction mechanism <NUM> according to the second embodiment will be mainly described below. Note that, in the following, constituent elements equivalent to constituent elements already described are denoted by the same reference signs as the above, and overlapping description will be omitted.

The pressure reduction mechanism <NUM> is embodied as a pressure reduction device <NUM>. As illustrated in <FIG>, the pressure reduction mechanism <NUM> of the pressure reduction device <NUM> includes a pressure reduction part <NUM>, and includes a plurality of flow-passage narrowing portions <NUM>. The plurality of flow-passage narrowing portions <NUM> are disposed to be spaced in a flow direction FD. Each flow-passage narrowing portion <NUM> is formed to include a flat plate-shaped portion extending substantially perpendicularly to the flow direction FD and having a hole <NUM>. That is, the pressure reduction part <NUM> of the pressure reduction mechanism <NUM> includes pressure reduction components in a plurality of stages. Here, three flow-passage narrowing portions <NUM> are provided, but the number of flow-passage narrowing portions <NUM> may be two or four or more.

<FIG> is a schematic view illustrating the three flow-passage narrowing portions <NUM> in a flow passage 111F in the pressure reduction device <NUM> as seen from an upstream side, and <FIG> is a cross-sectional view of the pressure reduction device <NUM> taken along the IIIB-IIIB line of <FIG>. Note that a description will be continued below on the assumption that the pressure reduction device <NUM> is used in an orientation as illustrated in <FIG>.

As is obvious from <FIG>, the hole <NUM> in each of the plurality of flow-passage narrowing portions <NUM> is disposed to be offset from the hole <NUM> in the adjacent flow-passage narrowing portion(s) <NUM>, that is, offset in a direction perpendicular to the axis AL of the flow passage 111F. In the pressure reduction device <NUM>, a most upstream hole 32H1 is positioned substantially at the cross-sectional center, a middle hole 32H2 in the flow direction is provided to be located on a lower side in a vertical direction VD, and a most downstream hole 32H3 is provided to be located on an upper side in the vertical direction VD. This can lower the degree to which steam having passed through one hole <NUM> directly passes through the next hole <NUM>, and accordingly enhance the pressure reduction effect. Note that the reason for positioning the most downstream hole 32H3 on the upper side in the vertical direction is mainly to prevent backflow of a drain liquid (i.e., liquid water) through the hole 32H3, as schematically illustrated in <FIG>.

Since the pressure reduction mechanism <NUM> of the pressure reduction device <NUM> is configured as described above, high-temperature and high-pressure steam is reduced in pressure by passing through the plurality of holes <NUM> one by one. Hence, in the steam trap system according to the second embodiment, steam and the like reduced in pressure in a stepwise manner by the plurality of holes <NUM> in the pressure reduction mechanism <NUM> is supplied into the steam trap <NUM>. This sufficiently lowers the degree of exposure of the steam trap <NUM> to high-temperature and high-pressure steam and can accordingly extend its service life.

Note that, in the pressure reduction device <NUM>, the sizes of the holes <NUM> in the plurality of flow-passage narrowing portions <NUM> are the same but may be different. For example, as illustrated in <FIG>, the upstream hole 32H1 may be the largest in diameter, and the holes 32H2 and 32H3 may be smaller in this order. Further, the holes 32H1, 32H2, and 32H3 may be offset not only in the vertical direction VD but also in a horizontal direction HD, as illustrated in <FIG>. In the case of providing a plurality of flow-passage narrowing portions <NUM>, the sizes and positions of their holes <NUM> are advantageously designed with at least one of, and preferably both of, pressure reduction of steam and backflow of a drain liquid into consideration. Note that it is possible to select a linear arrangement of the plurality of holes <NUM> in the flow direction, i.e., an arrangement in which the plurality of holes <NUM> overlap each other in a drawing corresponding to <FIG> or <FIG>.

While two embodiments and modifications thereof have been described above, the present invention is not limited to these. For example, the pressure reduction devices <NUM> and <NUM> are mechanically mounted in a detachable manner to the steam trap <NUM>. However, the pressure reduction devices <NUM> and <NUM> may be fixed to the steam trap <NUM> by welding or the like. Also, in the above embodiments and the like, a single hole <NUM> is provided in a single flow-passage narrowing portion <NUM>. However, a plurality of holes may be provided in a single flow-passage narrowing portion <NUM>.

Also, the pressure reduction mechanisms are not limited to the configurations including the hole(s) <NUM>, i.e., orifice(s), and may be formed to include a movable part, for example. For instance, the pressure reduction mechanisms may have a pressure reducing valve to enable adjustment of the pressure reduction effect via adjustment of the opening degree of that valve.

Also, the steam trap systems including the pressure reduction mechanisms may comprise a nozzle-type steam trap having a different configuration from that of the above steam trap <NUM>. Alternatively, the steam trap systems including the pressure reduction mechanisms may comprise a steam trap of a type other than the nozzle type, e.g., a steam trap including a movable part.

Claim 1:
A pressure reduction mechanism (<NUM>, <NUM>) to be provided upstream of a steam trap (<NUM>) so as to reduce a pressure of a fluid to be supplied into the steam trap, comprising
a pressure reduction part (<NUM>), wherein
the pressure reduction part includes a flow-passage narrowing portion (<NUM>), and
the flow-passage narrowing portion defines and forms a hole (<NUM>) extending in a flow direction and having such a dimension as to always permit a free flow of steam therethrough.