JPH0523975Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is an engine in a drainage pump station,
This relates to a cooling water cooler used for a reduction gear or a private power generator.

(Conventional technology) Conventionally, the engines and reducers at drainage pump stations were
As shown in FIGS. 4 to 6, a cooler 3 is provided between the discharge pipes 2 of the drainage pump 1, and the cooling water is cooled by the waste water passing through the discharge pipes 2. The cooler 3 has a plurality of linear cooling pipes 5 arranged in a casing 4 parallel to the discharge pipe 2 and concentrically, and both ends of the cooling pipe 6 are connected to a cooling water supply port 8. The cooling water outlet 9 is connected to a separate partition chamber 7, and the cooling water is cooled by drainage.

In general, in this type of cooler 3, the diameter C of the pitch circle passing through the center of the cooling pipe 5 is made larger than the inner diameter D of the discharge pipe 2, and the cooling pipe 5 is arranged on the outer periphery than the inner diameter D of the discharge pipe 2. (For example, JP-A-59-
56087 or Utility Model Application Publication No. 59-144368).

This is to prevent garbage such as cloth and vinyl contained in the drainage from the drainage pump 1 from getting caught in the cooling pipe 5, and to prevent damage to the cooling pipe 5 due to collisions with pieces of wood, etc. The purpose was to minimize the pressure loss caused by the cooler 3 to the main stream of waste water.

In other words, the total head of the drainage pump 1 used for flood and storm surge countermeasures is generally standardized in the range of several meters to more than ten meters (for example, the Technical Standards for Lifting and Drainage Pump Equipment of the Japan Construction Mechanization Association), and the This is because if the pressure drop caused by the device 3 is excessive, there is a risk that it will not be able to comply with this standard, and an increase in the pressure drop will immediately lead to an increase in the pump driving force, which will be uneconomical.

(Problems to be Solved by the Invention) In the conventional cooler, the inner diameter of the casing 4 housing the cooling pipe 5 is also larger than the inner diameter D of the discharge pipe 2. For this reason, air entering from the pump suction port during pump operation accumulates at the top of the casing 4 of the cooler 3, and a portion of the cooling pipe 5 is exposed to this air portion, thereby reducing the cooling capacity of the cooler 3. There was a problem with that.

In addition, normally, such a drainage pump 1 forms a siphon during operation, and the pressure at the top of the siphon is often a negative pressure below atmospheric pressure, so the air accumulated at the top of the casing 4 of the cooler 3 In order to evacuate the air, separate equipment such as a vacuum pump was required.

Furthermore, although the cooling pipe 5 was provided at a position on the outer periphery of the main flow where the main flow does not directly collide with it, the cooling effect tends to decrease as the cooling pipe 5 moves away from the main flow.

Therefore, in order to obtain a sufficient cooling effect, it is necessary to increase the heat transfer area by increasing the length or number of cooling pipes 5, and as a result, the casing 4 (i.e., the cooler 3) It had the problem of increasing its size.

It is empirically known that the extra-tube heat transfer coefficient, which represents the heat transfer performance on the outer surface of the cooling tube 5 of this type of cooler 3, is proportional to the average flow velocity V outside the tube to the 0.8th power. (For example, Proceedings of the Japan Society of Mechanical Engineers No.
833-2), increasing the diameter of the casing 4 lowers the average flow velocity V outside the tube and lowers the heat transfer coefficient outside the tube, which creates a vicious cycle in which a larger heat transfer area is required and the casing 4 becomes larger. I had fallen into a trap.

(Means for Solving the Problems) In order to solve the problems, the present invention provides that in the above type of cooler, the diameter C of the pitch circle passing through the center of the cooling pipe 5 is changed to the inner diameter D of the discharge pipe 2. It is smaller and larger than the inner diameter D of the discharge pipe 2 minus the outer diameter E of the cooling pipe 5.

(Example) Next, an example of the cooler according to the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows the conventional cooler 3 in which the cooling pipe 5 is arranged so that the diameter C of the pitch circle passing through the center of the cooling pipe 5 is smaller than the inner diameter D of the discharge pipe 2 by the outer diameter E of the cooling pipe 5. FIG. 3 shows an example in which the pitch circle diameter C is slightly smaller than the discharge pipe inner diameter D.

With this configuration, when air accumulates at the top of the casing 4, the water level drops to the upper end of the discharge pipe 2, but a portion of the surface of the cooling pipe 5 near the top of the casing 4 is slightly filled with air. The inside is only exposed. When the drain pump 1 is actually in operation, the water surface is irregularly undulating due to the water flow, and the exposure of the cooling pipe 5 to the air becomes smaller, so that the decrease in the cooling effect is negligible.

Furthermore, since the inner diameter of the casing 4 of the cooler 3 can be made smaller, the drop in the average flow velocity V outside the tube is also smaller, and as a result of the above-mentioned extra-tube heat transfer coefficient being increased, the length and number of cooling tubes 5 can be made smaller. The entire structure can be made compact, which is advantageous in terms of production costs and installation space.

On the other hand, the pressure drop that the cooler 3 gives to the main stream can be approximated by applying Weisbach's experimental formula for an orifice in a pipe, where d is the inner diameter of the partition chamber 7 where the cooling pipes 5 gather, and D is the inner diameter of the discharge pipe 2. can be calculated and expressed as follows.

HL=KVo ² /2G Here, HL: Pressure drop that one partition gives to the main stream of waste water, K: Resistance coefficient, Vo: Average flow velocity in the discharge pipe section, G: Gravitational acceleration.

That is, if the outer diameter E of the cooling pipe 5 is appropriately selected,
It is possible to make the inner diameter d of the partition chamber 7 0.9D or more, and as a result, the value of the resistance coefficient K becomes 0.3 or less according to Weisbach's experiment, and the pressure drop of the entire cooler 3 is lower than that of the conventional structure. This can be kept sufficiently small to within twice the amount.

In addition, the cooling pipe 5 is sandwiched between the partitions 7, which have both ends fixed, and is placed in a position where the main flow does not collide directly with the cooling pipe, so there is little risk of damage from collisions with wood chips, etc. Since the flow velocity is high, there is little possibility that dust such as cloth or vinyl gets entangled in the cooling pipe 5, and in these respects it is not inferior to the conventional structure.

(Effect of the invention) As is clear from the above explanation, according to the invention, the cooling pipe can be arranged so that the pitch circle diameter C passing through the center of the cooling pipe is slightly smaller than the inner diameter D of the discharge pipe. Even if air accumulates at the top of the cooler casing, the reduction in cooling effectiveness due to the exposure of the cooling pipe to the air is suppressed to a negligible level, and the inner diameter of the casing can be made smaller, making it possible to replace the conventional structure. In comparison, the decrease in the average flow velocity V outside the cooling pipe is small, and the heat transfer coefficient outside the pipe is increased. As a result, the length and number of cooling pipes can be reduced, and the entire cooler can be made compact.

Therefore, it is advantageous in terms of manufacturing cost and installation space.

On the other hand, with respect to the small pressure loss imparted to the main stream, which was a feature of the conventional structure, the pressure loss in the structure according to the present invention is sufficiently suppressed to within twice that of the conventional structure. It also has the same durability as conventional structures against dust getting entangled in the cooling pipes and collisions with woodcutters, etc.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the cooler according to the present invention, Fig. 2 is a sectional view of the cooler according to the present invention;
3 and 3 are cross-sectional views taken along the line A-A in FIG. 1 of the first and second embodiments, FIG. 4 is a diagram showing an application example of the cooler of the present invention, and FIG. 5 is a diagram of a conventional cooler. FIG. 6 is a sectional view taken along the line B--B in FIG. 5. 1... Drain pump, 2... Discharge pipe, 3... Cooler, 4... Casing, 5... Cooling pipe, 7... Partition room.

Claims (1)

[Scope of utility model registration request] Inside the casing provided between the discharge pipes of the drainage pump, a plurality of straight cooling pipes are arranged parallel to the discharge pipes and concentrically, and both ends of the cooling pipes are connected to the partition chamber. In the cooler, the diameter C of the pitch circle passing through the center of the cooling pipe is smaller than the inner diameter D of the discharge pipe, and the diameter C of the pitch circle passing through the center of the cooling pipe is smaller than the inner diameter D of the discharge pipe. A cooler characterized in that it is configured to be larger than a dimension obtained by subtracting an outer diameter E of a cooling pipe from D.