JP2012097964A - Filtration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filtration system for preventing deposition of sludge in a lower water tank in a cooling tower.SOLUTION: The filtration system which filtrates circulating cooling water stored in the lower water tank of an open circulating type cooling water system cooling tower for cooling the circulating cooling water by making the circulating cooling water make contact with external air, includes a filter for filtrating the circulating cooling water, a supply pipe for supplying the circulating cooling water in the lower water tank to the filter, and a return pipe for returning treated water treated by the filter to the lower water tank. The return pipe is extended into the lower water tank, and installed to circulate along an inner wall of the lower water tank. In the return pipe installed to circulate, a plurality of discharge ports for discharging the treated water toward the inner circumferential side is provided at predetermined intervals.

Description

  The present invention relates to a technique of a filtration system for filtering circulating cooling water stored in a lower water tank of an open circulation cooling water system cooling tower.

  In buildings and petrochemical plants, etc., cooling water widely used for the purpose of cooling refrigerator refrigerants and process fluids is generally (1) open circulation cooling water system, (2) closed circulation cooling water system, ( 3) It is classified into three types of transient cooling water systems. Among these, the open circulation type cooling water system is said to recycle and use the cooling water by evaporating a part of the cooling water whose temperature has risen in the heat exchanger in the cooling tower and cooling the cooling water by the latent heat of evaporation. It has a structure.

  In an open circulation type cooling water system, hardness components such as calcium and magnesium and silica etc. in the cooling water are concentrated by circulating the cooling water, so these components precipitate in the cooling water and are provided in the cooling tower as sludge. Deposited in the lower tank. Moreover, when earth and sand etc. are taken in into a cooling tower from the outside, these will accumulate in the lower water tank in a cooling tower as sludge.

  If the sludge accumulated in the lower water tank in the cooling tower circulates with the cooling water and adheres to and accumulates on the heat exchanger, it reduces the heat transfer efficiency of the heat exchanger or causes corrosion of metal materials such as the heat exchanger and piping. It is known to cause problems such as damage.

  In order to prevent sludge from accumulating in the lower water tank in the cooling tower, for example, in Patent Document 1, a part of the cooling water is drawn from the lower water tank in the cooling tower and is filtered by a filter provided outside the cooling tower. A filtration system that captures and separates sludge from cooling water and then returns the treated water to the lower water tank in the cooling tower has been proposed.

JP 2001-246203 A

  An object of this invention is to provide the filtration system which prevents that sludge accumulates in the lower water tank in a cooling tower.

  The present invention is a filtration system for filtering the circulating cooling water stored in a lower water tank of an open circulating cooling water system cooling tower that cools the circulating cooling water by bringing the circulating cooling water into contact with outside air. A filter for filtering cooling water, a supply pipe for supplying circulating cooling water of the lower water tank to the filter, and a return pipe for returning treated water treated by the filter to the lower water tank, The return pipe is installed in the lower water tank so as to circulate along the inner wall of the lower water tank, and the return pipe installed so as to circulate is subjected to the treatment toward the inner peripheral side. A plurality of discharge ports for discharging water are provided at predetermined intervals.

  Moreover, the said filtration system WHEREIN: It is preferable that the end of the said supply piping is connected to the connection port provided in the said lower water tank, and the said connection port is arrange | positioned in the center part of the said lower water tank.

  Moreover, in the said filtration system, it is preferable that the direction of the said discharge port shall be the range from a horizontal direction to 45 degrees downward with respect to a horizontal direction.

  According to the present invention, it is possible to prevent sludge from accumulating in the lower water tank in the cooling tower.

It is a schematic cross section which shows an example of the structure of the cooling tower which installed the filtration system which concerns on this embodiment. It is a schematic plan view of a lower water tank. (A) is a partial schematic plan view of the return pipe of the extended portion, and (b) is a schematic cross-sectional view of the return pipe along the AA line of (a). (A)-(c) is a partial schematic plan view which shows the other form of the return piping of an extending part. It is a schematic plan view of the lower water tank which shows the other form of the return piping of an extension part. (A), (b) is a schematic perspective view of the lower water tank which shows the other form of the return pipe of an extension part.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic cross-sectional view showing an example of a configuration of a cooling tower in which a filtration system according to the present embodiment is installed. The cooling tower 1 of the present embodiment is an open circulation type cooling water system cooling tower 1 that cools the circulating cooling water by bringing the circulating cooling water into contact with outside air. The lower part of the cooling tower 1 shown in FIG. 1 is a lower water tank 10 in which circulating cooling water is stored, and a part of the side wall of the cooling tower 1 above the lower water tank 10 is a louver for taking in outside air. 12, a filler 14 is installed inside the cooling tower 1 near the louver 12, and a fan 16 is installed above the cooling tower 1. A cooling water inlet 18 is provided at the center of the lower water tank 10 of the cooling tower 1 shown in FIG. Further, the cooling tower 1 shown in FIG. 1 is provided with the filtration system and the circulation system of the present embodiment.

  The structure of the circulation system is not particularly limited as long as it circulates the circulating cooling water in the lower water tank 10 to the filler 14 of the cooling tower 1, but the circulation system of the present embodiment is a circulation pipe 20. A pump 22 is provided. One end of the circulation pipe 20 is connected to a circulation connection port (not shown) provided in the cooling water suction port 18 of the lower water tank 10, and the other end is extended from the side wall of the cooling tower 1 to the inside of the cooling tower 1. , Open to the atmosphere toward the filler 14. The circulation pipe 20 is provided with a pump 22 and a heat exchanger 24.

  The filtration system of this embodiment includes a supply pipe 26, a pump 28, a filter 30, a return pipe 32, and blow pipes 34a and 34b. One end of the supply pipe 26 is connected to a filtration connection port (not shown) provided in the cooling water suction port 18 of the lower water tank 10, and the other end is connected to a filter 30. A pump 28 is installed in the supply pipe 26. One end of the return pipe 32 is connected to the filter 30, and the other end is extended from the side wall of the cooling tower 1 into the lower water tank 10 of the cooling tower 1. One end of the blow pipe 34 a is connected to the supply pipe 26, and the other end extends from the bottom of the cooling tower 1 into the cooling tower 1, and reaches the atmosphere above the liquid level of the circulating cooling water stored in the lower water tank 10. It is open. One end of the blow pipe 34b is connected to the supply pipe 26 on the downstream side of one end of the blow pipe 34a, and the other end is open to the atmosphere.

  FIG. 2 is a schematic plan view of the lower water tank. As shown in FIG. 2, in the present embodiment, the return pipe 32 a of the return pipe 32 that extends into the lower water tank 10 (hereinafter may be referred to as an extended part) is the inner wall of the lower water tank 10. It goes around and has a rectangular shape. Fig.3 (a) is a partial schematic plan view of the return piping of an extension part, and FIG.3 (b) is a schematic cross section of the return piping in the AA line of Fig.3 (a). As shown in FIG. 3 (a), a plurality of discharge ports 36 are provided at predetermined intervals in the return pipe 32a of the extending portion. Here, the predetermined intervals are not limited to equal and substantially equal intervals, and may be different intervals. The plurality of discharge ports 36 provided in the return pipe 32a of the extended portion are arranged on the inner peripheral side of the return pipe 32a of the extended portion (that is, opened toward the inner peripheral side). As will be described later, as shown in FIG. 2, the treated water treated by the filter 30 is discharged from the discharge port 36 toward the inner peripheral side of the return pipe 32a.

  Below, operation | movement of the cooling tower 1 shown in FIG. 1 is demonstrated.

  The pump 22 is operated, and the circulating cooling water in the lower water tank 10 is supplied from the circulation pipe 20 to the heat exchanger 24. The circulating cooling water is heat-exchanged by the heat exchanger 24, becomes cooling water whose water temperature has risen, and is sprinkled from the upper part of the cooling tower 1 to the filler 14 through the circulation pipe 20. The cooling water sprayed on the filler 14 comes into contact with the air sucked from the louver 12 by the fan 16, partly evaporates and becomes a cooling water whose water temperature is lowered by releasing the latent heat of evaporation, and the lower water tank 10 falls and is stored.

  By circulating the circulating cooling water in this way, hardness components such as calcium and magnesium, silica, and the like in the circulating cooling water are concentrated. Sludge is generated when these components become supersaturated and precipitate in the circulating cooling water, or when earth and sand are taken into the cooling tower 1 from the outside, and microbial metabolites are mixed. Therefore, the filtration system of this embodiment is operated periodically or continuously to remove sludge.

  In the filtration system of the present embodiment, first, the pump 28 is operated, and the circulating cooling water including the sludge in the lower water tank 10 is supplied from the supply pipe 26 to the filter 30. And the sludge in circulating cooling water is removed in the filter 30. The treated water that has passed through the filter 30 passes through the return pipe 32 and is returned into the lower water tank 10.

  As shown in FIG. 2, in the lower water tank 10, treated water is discharged from the discharge port provided in the return pipe 32a of the extending portion toward the inner peripheral side of the return pipe 32a. In this manner, the treated water is convected toward the center of the lower water tank 10 by discharging the treated water from the plurality of discharge ports toward the inner peripheral side of the return pipe 32a. Therefore, the sludge in the lower water tank 10 is present in a relatively floating and dispersed state in water, and accumulation at corners of the lower water tank 10 is suppressed.

  In general, when sludge accumulates, sludge becomes agglomerated with circulating cooling water, passes through the circulation piping, and adheres to and accumulates on the heat exchanger, reducing the heat transfer efficiency of the heat exchanger, and heat exchangers and piping. There is a risk of causing problems such as corrosion of metal materials such as. Therefore, maintenance such as periodically cleaning the inside of the cooling tower is required. However, in the present embodiment, as described above, sludge is relatively floated and dispersed in water, and sludge accumulation is suppressed, so that the filtration efficiency by the filter 30 is improved and the sludge lump is circulated. The harmful effects of passing through 20 can be suppressed. As a result, it is possible to reduce the number of maintenances such as periodic cleaning.

  The detailed configuration of each part will be described below.

  It is preferable that the space | interval of the discharge port 36 provided in the return piping 32a of an extension part is the range of 300-500 mm. Moreover, it is preferable that the magnitude | size of the discharge port 36 is the range of (phi) 3-5 mm. Further, as shown in FIG. 3B, the direction (direction) of the discharge port 36 is preferably in a range from the horizontal direction to the 45 ° downward direction with respect to the horizontal direction. If the interval, size, and direction of the discharge ports 36 are outside the above range, the treated water is difficult to convect toward the inner peripheral side of the return pipe 32a (substantially, the treated water is directed toward the center of the lower water tank 10). In some cases, sludge accumulates in the corners of the lower water tank 10 or the like.

  FIGS. 4A to 4C are partial schematic plan views showing other forms of the return piping of the extending portion. As shown in FIG. 4 (a), a plurality of discharge ports 36 facing in the horizontal direction and a plurality of discharge ports 36 facing downward (for example, 45 °) with respect to the horizontal direction may be randomly arranged at predetermined intervals. . Thereby, since the treated water discharged toward the inner peripheral side of the return pipe 32a becomes a turbulent flow, the dispersibility of the sludge in the lower water tank 10 is improved, and sludge accumulation can be further suppressed. Moreover, as shown in FIG.4 (b), since the process water discharge | released toward the inner peripheral side of the return piping 32a also becomes a turbulent flow by providing a level | step difference in the return piping 32a, in the lower tank 10 Dispersibility of sludge is improved, and sludge accumulation can be further suppressed. FIG.4 (c) is the figure which looked at return piping from upper direction. As shown in FIG.4 (c), you may install the shielding board 38 which changes the flow of the treated water discharge | released from the discharge port 36 in the return piping 32a. Thereby, since the treated water discharged toward the inner peripheral side of the return pipe 32a becomes a swirling flow, the dispersibility of the sludge in the lower water tank 10 is improved, and sludge accumulation can be further suppressed.

  FIG. 5 is a schematic plan view of a lower water tank showing another form of the return pipe of the extending portion. The part of the return pipe 32a extending into the lower water tank 10 circulates along the inner wall of the lower water tank 10, but as shown in FIG. 5, the part where the return pipe 32a is not installed partially. It may be provided. That is, if the sludge in the lower water tank 10 can be dispersed by the treated water that convects toward the inner peripheral side of the return pipe 32a, the return pipe 32a of the extended portion is completely along the inner wall of the lower water tank 10. There is no need to go around. For example, the return pipe 32 may circulate at least 3/4 of the inner circumference along at least the inner wall of the lower water tank 10.

  6A and 6B are schematic perspective views of a lower water tank showing another form of the return pipe of the extending portion. As shown in FIG. 6 (a), a cooling water suction port 18 having a filtration connection port (not shown) arranged in a rectangular parallelepiped lower water tank 10 is provided, and a supply pipe (not shown) is provided in each filtration connection port. In the case of the lower water tank 10 that is connected, the return pipe 32a is provided between the circulation pipe 40 that circulates along the inner wall of the lower water tank 10 and the cooling water suction port 18 (between the connection ports). It is preferable to include a connecting pipe 42 that connects the 40 longitudinal pipes. Although not shown in the figure, a plurality of discharge ports are provided at predetermined intervals on the inner peripheral side of the circulation pipe 40 and the connection pipe 42. As shown in FIG. 6B, the rectangular parallelepiped lower water tank 10 is divided into a plurality of chambers (10a, 10b, 10c) by a separator, and a cooling water suction provided in each chamber (10a, 10b, 10c). In the case of the lower water tank 10 in which a supply pipe (not shown) is connected to a filtration connection port (not shown) of the port 18, the return pipe 32a is provided for each of the divided chambers (10a, 10b, 10c). It is preferable to arrange | position so that it may wrap around along the inner wall.

  The connection port for filtration to which one end of the supply pipe 26 is connected may be provided at any position of the lower water tank 10, but is preferably provided at the center of the lower water tank 10. Like this embodiment, the return piping 32a extended in the lower water tank 10 is arrange | positioned so that it may circulate along the inner wall of the lower water tank 10, and treated water is sent to the return piping 32a to the inner periphery. Since the discharge port 36 that discharges toward the side is provided, the fluid in the lower water tank 10 easily flows toward the center of the lower water tank 10, and sludge also easily flows in the center. Therefore, if the connection port for filtration is provided in the central portion of the lower water tank 10, the sludge can be easily taken from the connection port for filtration, so that the sludge removal rate by the filter 30 can be improved. The central portion is, for example, a region within 1/3 from the center with respect to the distance from the center to the inner wall in the horizontal section of the lower water tank 10.

  The filter 30 which concerns on this embodiment will not be restrict | limited especially if the sludge in circulating process water can be removed, For example, a membrane filtration apparatus, a filter medium filling filter, etc. can be mentioned. Although there is no restriction | limiting in particular in the filtration membrane used for a membrane filtration apparatus, MF membrane, UF membrane, etc. can be used suitably. Although there is no restriction | limiting in particular in the filter medium used for a filter medium filling filter, Sand, anthracite, etc. can be used suitably.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

Example 1
The cooling tower shown in FIG. 1 was operated under the following conditions, and the turbidity of the circulating cooling water flowing through the circulation piping was measured. The lower water tank and the return pipe extending in the lower water tank of the cooling tower in Example 1 used the lower water tank and the return pipe shown in FIG.

  The operation condition of Example 1 was that the filtration system was operated for 17 days after the operation was performed without operating the filtration system for 5 months from the start of the test. Sampling of the turbidity of the circulating cooling water was performed immediately after the start of the test, 5 months later, 1 day after the filtration system was activated, and 10 days after the filtration system was activated. The results are summarized in Table 1.

<Cooling tower of Example 1>
Cooling tower: Open cooling tower 400RT
Filter: One sand filtration device
Maximum flow rate: 8m ³ / h
Filter media type: sand
Filter media weight: 100kg
Filtration area: 0.2288 m ³
Filtration tank dimensions: Height 870mm x φ530mm
Discharge port diameter: φ4mm
Distance between discharge ports: 300mm
Direction of discharge port: 45 degrees below the horizontal direction

(Example 2)
The test was performed under the same conditions as in Example 1 except that the cooling tower capacity was 1000 RT and two sand filtration devices were installed. Sampling of the turbidity of the circulating cooling water was carried out in the same manner as in Example 1, immediately after the start of the test, 5 months later, 1 day after the filtration system operation, and 10 days after the filtration system operation. The results are summarized in Table 2.

  As can be seen from Tables 1 and 2, in both Examples 1 and 2, the turbidity of the circulating cooling water increased from the start of the test to the operation of the filtration system, but the turbidity and SS were increased by operating the filtration system. The concentration decreased, and the turbidity was 1 or less 10 days after the filtration system was activated. As in Examples 1 and 2, the return pipe extending into the lower water tank is arranged so as to circulate along the inner wall of the lower water tank, and the treated water is put into the return pipe extended into the lower water tank. By installing a discharge port that discharges toward the circumferential side, the convection of the circulating cooling water in the lower aquarium has been improved, and sludge accumulation at the corner of the lower aquarium has been suppressed. It was considered that the turbidity and SS concentration of the circulating cooling water were reduced because the sludge removal rate could be improved. Thereby, compared with what the filtration system of Example 1 and 2 is not installed, the frequency | count of maintenance, such as cleaning in a lower water tank, can be reduced.

  DESCRIPTION OF SYMBOLS 1 Cooling tower, 10 Lower water tank, 10a-10c chamber, 12 louvers, 14 Filler, 16 Fan, 18 Cooling water suction inlet, 20 Circulation piping, 22, 28 Pump, 24 Heat exchanger, 26 Supply piping, 30 Filter 32, 32a return pipe, 32a return pipe, 34a, 34b blow pipe, 36 discharge port, 38 shielding plate, 40 loop pipe, 42 connecting pipe.

Claims (3)

A filtration system for filtering the circulating cooling water stored in a lower water tank of an open circulating cooling water system cooling tower that cools the circulating cooling water by bringing the circulating cooling water into contact with outside air,
A filter for filtering the circulating cooling water;
A supply pipe for supplying the cooling water in the lower tank to the filter;
A return pipe for returning the treated water treated by the filter to the lower aquarium,
The return pipe is extended into the lower water tank and installed so as to circulate along the inner wall of the lower water tank,
The return pipe installed so as to circulate is provided with a plurality of outlets for discharging the treated water toward the inner circumference side at a predetermined interval.   2. The filtration system according to claim 1, wherein one end of the supply pipe is connected to a connection port provided in the lower water tank, and the connection port is disposed in a central portion of the lower water tank.   The filtration system according to claim 1 or 2, wherein the direction of the discharge port is in a range from a horizontal direction to a downward direction of 45 ° with respect to the horizontal direction.

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