JP3303943B2 - Method of removing microorganisms in heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing microorganisms in a heat exchanger using ozone gas.

[0002]

2. Description of the Related Art Conventionally, in a thermal power plant or the like, there is a condenser which is a kind of a heat exchanger for cooling steam used for power generation. In order to cool this type of condenser, seawater is usually used to continuously circulate through the condenser.
However, a large amount of microorganisms and the like are contained in seawater, and when they proliferate, inconveniences such as blockage of minute heat transfer tubes in the condenser and deterioration of the heat exchanger are caused. Therefore, there is an ozone treatment method for removing microorganisms using ozone gas having a bactericidal action for the purpose of avoiding propagation of microorganisms.

[0003] As this type of ozone treatment method, for example, a method disclosed in Japanese Patent Publication No. 59-34279 is known. That is, all the seawater in the condenser is drained, and then the ozone gas is injected into the condenser to remove microorganisms and the like with the ozone gas.

[0004]

However, microorganisms and the like are not sterilized by the ozone gas itself, but are sterilized by activated oxygen generated immediately after being decomposed by contact with moisture contained in the air or the like. Depending on the dry state after draining the cooling water from the condenser, the ozone gas is hardly decomposed into activated oxygen. For this reason, the amount of activated oxygen generated in the condenser is reduced, and there is a problem that the germicidal action of microorganisms is reduced.

[0005] The present invention has been made in view of the problems existing in such conventional techniques, and an object of the present invention is to make it possible to easily decompose ozone gas into activated oxygen. It is an object of the present invention to provide a method for removing microorganisms in a heat exchanger capable of obtaining an effective sterilizing action.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a heat exchanger for exchanging heat discharged from equipment with cooling water, wherein the microorganisms propagated in the heat exchanger are sterilized. in the sterilization method of the heat exchanger for injecting the ozone gas to, and discharging the cooling water from the heat exchanger, drain into the heat exchanger
The gist of the invention is to mix and inject water-saturated air from which excess water has been removed by an air discharger and ozone gas.

[0007]

According to the present invention thus constructed, after draining the cooling water from the heat exchanger, excess water is removed by the drain discharger.
The obtained water-saturated air and ozone gas are mixed and injected.
Then, the ozone gas comes into contact with the saturated steam contained in the moisture-saturated air and is quickly decomposed into activated oxygen. Therefore, a large amount of activated oxygen is generated even with a small amount of ozone gas, and a strong bactericidal action can be obtained. In addition, drain drain
Injection of moisture-saturated air from which excess moisture has been
During sterilization, microorganisms adhering to the heat exchanger
The formation of a water film covering the surface can be prevented. One
In other words, activated oxygen is biased against microorganisms in this water film.
Contact evenly, so that the inside of the heat exchanger is evenly sterilized
be able to.

[0008]

【Example】

(First Embodiment) A first embodiment in which the present invention is applied to a cooling unit for a thermal power plant will be described below with reference to the drawings.

As shown in FIG. 1, a cooling unit 1 for a thermal power plant is installed on a steam discharging path in order to cool and reuse high-temperature steam discharged from a generator during thermal power generation. . The cooling unit 1 includes a condenser 2 as a heat exchanger. The condenser 2 has a seawater supply pipe 3 connected to a seawater supply port (not shown),
Seawater discharge pipe 4 connected to a seawater outlet not shown
It is connected to the.

On the seawater supply pipe 3, a partition valve 5 for adjusting the supply amount of seawater is provided. A partition valve 6 for adjusting the amount of seawater discharged is provided on the seawater discharge pipe 4. Therefore, the cooling seawater taken in from the supply port is discharged from the discharge port through the seawater supply pipe 3, the condenser 2, and the seawater discharge pipe 4. Then, when cooling the steam, heat exchange is performed between the seawater supplied to the condenser 2 and the high-temperature steam,
As a result, the steam is cooled to a predetermined temperature. A drain pipe 22 having a drain valve 21 for drainage is connected to the condenser 2. One side of the condenser 2 is connected to an ozone gas supply pipe 7 having a valve 23, and a distal end of the pipe 7 is connected to a compressor 8.

An air introduction pipe 25 having a valve 24 is connected between the condenser 2 and the valve 23 on the pipe 7. On the pipe 7, an air volume adjusting valve 9 capable of adjusting the air volume from the compressor 8 is interposed. An ozonizer 10 for generating ozone is connected to the pipe 7 via an ozone supply pipe 11 having an ozone injection adjusting valve 12. The humidifier 1 is placed on the pipe 7.
3 is connected via a moisture supply pipe 14 having a humidification adjusting valve 15.

A drain trap 19 is interposed on the pipe 7 between the ozone supply pipe 11 and a connection point with the humidification adjusting valve 15. Drain trap 1
At 9, the air mixed with moisture from the humidifier 13 is adjusted to moisture-saturated air, and the excess moisture of the moisture is discharged to the discharge pipe 20.
Is discharged through.

A discharge ozone treatment tower 18 is provided at an outlet of the condenser 2.
Is connected through an exhaust pipe 16 provided with a valve 17. The unreacted ozone gas after the ozone treatment in the exhaust ozone treatment tower 18 is decomposed and released to the atmosphere after eliminating its toxicity.

Next, a method for removing microorganisms that have propagated in the condenser 2 with ozone gas will be described. In performing the ozone treatment, the partition valves 5 and 6 are closed, the drain valve 21 and the air introduction valve 24 are opened, and the seawater in the condenser 2 is discharged to the outside. Thereafter, the drain valve 21 and the air introduction valve 24 are closed, and the condenser 2
The connection between the internal area and the external area is interrupted.

Then, the air volume adjusting valve 9, the ozone injection adjusting valve 12, the humidifying adjusting valve 15 and the valve 17 are simultaneously opened. Then, the pipe 7, the inside of the condenser 2, and the exhaust pipe 16 are communicated. When the compressor 8 is operated, the compressed air is supplied from the compressor 8 to the humidifier 13.
Is sent to the drain trap 19 via the pipe 7 together with the moisture from the pump. The humidity is adjusted to a predetermined level in the drain trap 19, and only moisture-saturated air from which excess moisture has been removed is discharged. The discharged moisture-saturated air is supplied to the ozonizer 10.
The mixture is mixed with the ozone gas generated in the step (1), and the mixture is pressure-fed into the condenser (2).

The ozone gas injected into the condenser 2 comes into contact with saturated steam contained in the moisture-saturated air and is efficiently and quickly decomposed into activated oxygen. The activated oxygen and the microorganisms in the condenser 2 come in contact with each other to be sterilized. At this time, since the moisture-saturated air and the ozone gas are mixed immediately before being injected into the condenser 2, they are not decomposed into activated oxygen in the pipe 7, and are activated immediately after being injected into the condenser 2. Decomposed into oxygen.

Also, during sterilization, the saturated steam contained in the mixture of the moisture-saturated air and the ozone gas does not form a water film on the inner surface of the condenser 2, so that the activated oxygen decomposed from the ozone gas is hindered by the water film. Without contacting the inside of the condenser. That is, the activated oxygen is uniformly contacted with the microorganisms without bias, and the bactericidal power is made uniform. After the sterilization treatment, the exhausted ozone is introduced into the exhausted ozone treatment tower 18 via the exhaust pipe 16, and is decomposed into oxygen from the exhausted ozone treatment tower 18 and discharged to the atmosphere.

Therefore, by mixing ozone gas and moisture-saturated air, the ozone gas is rapidly decomposed into activated oxygen in a short time, and a large amount of activated oxygen is generated even with a small amount of ozone gas. Obtainable. Therefore, the sterilization ability can be improved, and the size of the ozonizer can be reduced. That is, it is possible to reduce the running cost such as the manufacturing cost, the equipment cost, and the operating cost of the cooling unit 1.

Also, by mixing ozone gas with moisture-saturated air whose humidity has been adjusted by the drain trap 19,
During sterilization, it is possible to prevent the formation of a water film covering the surface of the microorganisms attached to the condenser 2. That is, since the activated oxygen is not hindered from contacting the microorganisms in the water film, the inside of the condenser 2 can be uniformly sterilized.

Further, the ozone gas is rapidly decomposed into activated oxygen in a short time, so that the sterilization time can be shortened. As a result, the stop time of seawater circulation (circulating cooling water) during sterilization can be greatly reduced.

It should be noted that the present invention is not limited to the above embodiment, and may be appropriately changed as follows without departing from the spirit of the present invention. (1) For example, each valve 15, 17, 21, 23, 24
May be changed to any type of solenoid valve or manual valve.

(2) A blower may be used instead of the compressor 8. (3) The waste ozone after the sterilization treatment may be returned to the input system such as the pipe 7 and reused.

[0023]

According to the present invention as described in detail above, by easily decomposes the ozone gas to the activated oxygen, low
It can be obtained a strong bactericidal action even in amounts of ozone gas
At the same time, the excess water is
By injecting Japanese air, heat exchanger during sterilization
To prevent the formation of a water film inside, and evenly kill the inside of the heat exchanger.
It has an excellent effect of being able to germ .

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a cooling unit in the present embodiment.

[Explanation of symbols]

2: Condenser (heat exchanger) 19: Drain trap (drain )
Ejector)

Continued on the front page (72) Inventor Atsushi Kawachi 1st character small needle in Inuyama City, Aichi Prefecture Energy Support Co., Ltd. References JP-A-2-57167 (JP, A) JP-A-4-15060 (JP, A) JP-B-59-34279 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) F28F 19/01

Claims (1)

(57) [Claims] 1. A method for removing microorganisms in a heat exchanger for exchanging heat discharged from equipment with cooling water, the method comprising injecting ozone gas to sterilize microorganisms propagated in the heat exchanger. Drain the cooling water from the heat exchanger and drain into the heat exchanger
A method for removing microorganisms in a heat exchanger, which comprises mixing and injecting moisture-saturated air from which excess moisture has been removed in a heat exchanger and ozone gas.