KR100952155B1 - An acid cleaning apparatus and acid cleaning method for a multiple stage flashing facility - Google Patents

Abstract

The present invention relates to a multi-stage evaporative desalination plant (MSF: Multiple Stage Flash), and more particularly, to an acid washing apparatus of a multi-stage evaporative desalination plant that allows the condenser tube of the desalination plant to be easily washed with an acid solution. In the multi-stage evaporative desalination plant equipped with an evaporator divided into a heat recovery section and a heat shield section, the acidic injecting acidic acid into the evaporator is connected to the discharge pipe for discharging the concentrated salt water of the heat shield section. A liquid storage tank; A transfer pump for forcibly transferring the acidic liquid of the acidic liquid storage tank to the discharge pipe; It is configured to include; an opening and closing valve for opening and closing the transfer of the acidic liquid of the acidic liquid storage tank.

Accordingly, the hassle of installing a separate mobile acid washing device for acid cleaning of the desalination plant is eliminated, and as the facility capacity of the desalination plant is increased, the hassle of having to newly manufacture a mobile acid washing unit is eliminated, and the evaporator and the mobile acid are removed. This eliminates the hassle of installing temporary piping to connect to the cleaning device.

MSF, Desalination Plants, Washing

Description

An acid cleaning apparatus and acid cleaning method for a multiple stage flashing facility}

The present invention relates to a multi-stage evaporative desalination plant (MSF: Multiple Stage Flash), and more particularly, an acid washing apparatus of a multi-stage evaporative desalination plant that allows the condenser tube of the desalination plant to be easily washed with an acid solution. It relates to an acid washing method using the same.

In general, desalination facilities produce fresh water that can use seawater and sewage as domestic or industrial water. In general, multiple stage evaporation (MSF) and multiple effect distillation (MED) are mainly used. In addition, there is a reverse osmosis method using pressure as a membrane filtration method and a hybrid type using a mixture of the above methods.

In particular, the desalination plant by the multi-stage evaporation method is composed of a plurality of stages 111, as shown in Figure 4, is provided with an evaporator 110 divided into a heat recovery section (110a) and a heat shield section (110b). The stage 111 includes a condenser 112, a water separator 113, and a flashing chamber 114.

In addition, one side of the evaporator 110 is a brine heater (Brine Heater) for heating the preheated circulating brine (Recycling Brine) preheated to the operating temperature using the heat energy of the low-pressure steam supplied through the steam supply pipe ( 120 is provided, the other side of the evaporator 110 is provided with a deaerator (130) for removing carbon dioxide and oxygen contained in the feed-up (Make-up) flowing into the last stage of the evaporator.

Then, the condensate recovery pump 140 is connected to the brine heater 120 so that the condensed water in the brine heater 120 to the power generation facility for reuse, the concentrated brine so that the circulating brine can circulate inside the evaporator Brine Recirculation Pump (150) is provided, the fresh water pump 160 for sending the fresh water condensed by the evaporator to the post-treatment process and the concentrated brine discharge pump 170 for discharging the concentrated brine reaching the last stage of the evaporator (170). ) Is provided.

A vacuum system 180 is provided as a means for removing non-condensable gases such as carbon dioxide and air that are not condensed in the evaporator 110, and the vacuum system 180 is supplied through the steam supply pipe 181. A first pre-ejector 182 and a second pre-ejector 183 are provided, which eject the middle pressure steam to the internal nozzle to drastically reduce the pressure, and are sucked from the evaporator by the difference in pressure. First, second, and third condensers (184, 185, 186) for condensing non-condensable gas with cold concentrated brine introduced through the concentrated brine inlet (189) are provided, and a third condenser is provided. The condensed water inside is discharged to the atmosphere through the concentrated brine discharge pipe 187, and the non-condensable gas inside the third condenser 186 is discharged to the atmosphere through the gas discharge pipe 188.

The desalination plant by the multi-stage evaporation method configured as described above flows into the concentrated brine heater 120 through the condenser 112 of each heat recovery section by the concentrated brine circulation pump 150 and is supplied from the steam supply pipe 181. It is heated by the heat of condensation of low pressure steam.

In addition, the heated circulating brine is sequentially introduced into the evaporation chamber 114 of the stage 111, which is maintained at a low pressure, and the introduced circulating brine is violently flashed due to the low pressure around the evaporation chamber. Evaporation is continued while the incoming circulating brine is cooled to the boiling point corresponding to the pressure of the stage, and then flows to the next stage to repeat the process as described above and gradually increase the concentration. .

In order to adjust the concentration of the total circulating brine to reach the final stage, a part is discharged through the Brine Blowdown Pump 170, and the steam generated inside each evaporation chamber 114 is separated from the separator 113. Granules of salts that may be contained therethrough are removed, exchange heat with circulating brine flowing through the condenser 112 tube, and condense them into fresh water to be transferred to a post-treatment process through a distillate pump 160. Will be.

In addition, in the multi-stage evaporative desalination plant as described above, foreign matter is precipitated in the evaporation chamber 114, the condenser 112, and the water separator 113 provided in the evaporator 110. As there is a problem of contamination of fresh water produced in the desalination plant, it is necessary to periodically clean the evaporator.

In order to clean the evaporator 110, a mobile acid washing apparatus 300 is used to circulate and wash an acid solution capable of dissolving foreign substances into the evaporator 110, and the mobile acid washing apparatus 300 is typically After the acid dilution tank 302 and the transfer pump 303 is installed in the trolley 301 to move the trolley to a position where it is easy to work, the supply pipe 304 for circulating acidic liquid in the pipe connected to the evaporator 110 and A temporary pipe such as a recovery pipe 305 is installed, and the distilled water supply pipe 306 to which the distilled water is supplied to the acid dilution tank and the acidic liquid storage tank 307 are connected to each other so that the distilled water and the acidic liquid are separated from the acid dilution tank 302. The dilution is performed while being circulated into the evaporator 110 while being circulated.

However, as the conventional mobile acid washing apparatus as described above requires a separate large-capacity transfer pump 303 and temporary piping for circulating the acidic liquid, manpower and equipment required for washing work are excessively required. In addition, it takes a lot of time to connect the temporary piping has a problem that the overall operation stop time of the desalination plant is long.

In addition, when the capacity of the desalination plant is increased, the size of the mobile acid washing apparatus must also be increased, so that there is a problem of having to manufacture a separate mobile acid washing apparatus again.

Accordingly, the present invention has been made to solve the conventional problems as described above, the object of the present invention is that it is possible to acid wash the inside of the evaporator using a conventional pipe in a simple configuration without using a mobile acid washing apparatus. An acid washing apparatus of a multi-stage evaporative desalination plant is provided.

In addition, an object of the present invention is to allow the corrosion inhibitor to be added at the same time when the acidic liquid is injected.

On the other hand, it is an object of the present invention to provide an acid washing method of a multi-stage evaporative desalination plant that can easily and quickly acid wash the evaporator while minimizing additional equipment.

In addition, an object of the present invention is to minimize the corrosion of the pipe by the acid solution.

It is also an object of the present invention to remove air and carbon dioxide contained in the washing water during the washing operation without additional equipment.

In order to achieve the above object, the present invention is a multi-stage evaporative desalination plant equipped with an evaporator divided into a heat recovery section and a heat shield section, the evaporator is connected to the discharge pipe for discharging the concentrated salt water of the heat shield section An acid solution storage tank for injecting an acid solution into the inside of the container; A transfer pump for forcibly transferring the acidic liquid of the acidic liquid storage tank to the discharge pipe; Opening and closing valve for opening and closing the transfer of the acidic solution of the acidic storage tank; includes, Corrosion inhibitor storage tank to supply and mix the corrosion inhibitor for inhibiting the corrosion of the pipe to the acidic liquid discharged from the acidic liquid storage tank is It is characterized in that the further provided.

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On the other hand, the present invention is provided with an evaporator divided into a heat recovery section and a heat shield section, the multi-stage evaporation desalination equipment having a concentrated brine heater for heating the concentrated brine circulating the inside of the evaporator using a high temperature steam. An acid washing method comprising: distilled water injection step of filling distilled water into the heat recovery section and a heat shield section; By operating one or more transfer pumps disposed between the heat recovery section and the heat shield section, the distilled water injected in the distilled water injection step circulates inside the multi-stage evaporative desalination plant, and at the same time, hot steam to the concentrated brine heater. A circulation and heating step of heating the distilled water by supplying it; An acid solution injection step of intermittently injecting an acid solution into distilled water circulating between the heat recovery section and the heat shield section; After acidified distilled water circulates between the heat recovery section and the heat shield section for a certain time, seawater is introduced into the heat shield section to neutralize the acidified distilled water, and the neutralized distilled water is discharged to the outside of the desalination plant by washing the inside of the evaporator. Neutralizing step to make; Washing and rinsing the effluent by circulating the seawater after the distilled water and the acidic liquid are completely discharged; It is configured to include.

In addition, in the acidic liquid injection step, it is characterized in that the corrosion inhibitor to prevent corrosion of the pipes are injected at the same time.

In addition, in the acidic liquid injection step, all the ventilation valves installed in the evaporator is opened so that air and carbon dioxide are completely discharged to the outside of the evaporator.

Accordingly, the present invention provides an acid washing apparatus of a multi-stage evaporative desalination plant that allows acid washing of the inside of the evaporator using a conventional pipe in a simple configuration without using a mobile acid washing apparatus. Not only does the hassle of installing a separate mobile acid washer for the sake of disappearing, but also increases the capacity of the desalination plant. The hassle of installing pipes is eliminated.

In addition, an object of the present invention is to add a corrosion inhibitor at the same time when the acidic liquid is injected, it is possible to minimize the corrosion of the pipe to further increase the service life of the desalination plant, as well as the equipment required for injecting the corrosion inhibitor Will have the effect of minimizing.

On the other hand, the present invention provides an acid washing method of a multi-stage evaporative desalination plant that can easily and quickly acid wash the evaporator while minimizing the need for additional equipment, thereby minimizing operation downtime of the desalination plant for cleaning. Not only will the efficiency be further increased, but also the effect of reducing the manpower requirements for acid cleaning of the desalination plant.

In addition, the present invention by minimizing the corrosion of the pipe by the acidic liquid, it is possible to keep the pipe clean to easily prevent the generation of rust in the fresh water, as well as to further increase the service life of the desalination plant Will have

In addition, the present invention can remove the air and carbon dioxide contained in the wash water during the washing operation without additional equipment, thereby having an effect of more efficiently reducing the damage of the evaporator by air and carbon dioxide.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic block diagram showing an embodiment of the present invention, as shown in the present invention relates to an acid washing apparatus 200 for washing the evaporator 110 of the multi-stage evaporative desalination plant using an acidic solution. As an acid solution storage tank 201, a transfer pump 202 and an on / off valve on one side of a multi-stage evaporative desalination facility having an evaporator 110 divided into a heat recovery section 110a and a heat shield section 110b. When combined with an acid washing device consisting of 203, it is possible to perform a washing operation simply and quickly without the hassle of installing a separate mobile washing device when acid washing the evaporator (110).

The acidic liquid storage tank 201 stores an acidic liquid for acid washing the condenser 112 and the like in the evaporator 110, and is formed as a conventional storage tank for storing a liquid, and is typically used for desalination equipment. Hydrogen chloride (HCl 33%) solution used for the acid wash is stored so that the acidic solution is circulated along the pipe of the desalination plant to clean various foreign matters accumulated in the interior of the pipe and the inside of the evaporator (110).

At this time, the acidic liquid storage tank 201 is connected to the discharge pipe discharged from the brine in the heat shield section 110b, the acidic liquid supplied from the acidic liquid storage tank 201 is smoothly along the piping of the desalination plant. It is desirable to allow circulation.

The transfer pump 202 is to force the acidic liquid stored in the above-described acidic liquid storage tank 201 to the pipe of the desalination plant, the concentrated salt water in the acidic liquid storage tank 201 and the heat shield section (110b). It is coupled between the discharge pipe is discharged to prevent the backflow of the acidic liquid by the pressure of the washing water to circulate the desalination plant during the washing process of the desalination plant while a certain amount is smoothly supplied to be added to the washing water.

The on-off valve 203 opens and closes to supply or block the acidic liquid stored in the above-described acidic liquid storage tank 201, and is formed as a normal on-off valve to open only when the acidic liquid is supplied. To prevent the contamination of fresh water due to unnecessary addition of acidic liquids.

Accordingly, the separate pipe is connected every time the desalination plant is washed with an acidic solution, and the trouble of installing a mobile washing unit coupled to a trolley disappears, and when the facility capacity of the desalination plant is increased, the mobile washing is performed. Increasing the capacity of the device will eliminate the hassle of creating a new one.

In addition, one side of the acidic storage tank 201 is stored in the corrosion inhibitor to be supplied with a corrosion inhibitor to prevent the pipe from being corroded by the acidic liquid discharged from the acidic liquid storage tank 201 is mixed with the acidic liquid. By further including the tank 204, it is preferable to easily inject and mix the corrosion inhibitor during the cleaning of the desalination plant using the acidic liquid.

Figure 2 is a block diagram showing an acid washing method of a multi-stage evaporative desalination plant according to the present invention, Figure 3 shows an acid washing process of a multi-stage evaporative desalination plant according to the present invention, the acid washing apparatus configured as described above The process of washing the multi-stage evaporative desalination plant by using the distilled water injection step (S1) of filling the distilled water into the evaporator 110 as shown, while circulating the distilled water injected into the evaporator 110 at a constant temperature Circulation heating and heating step (S2), acidic solution injection step of adding an acidic solution to the distilled water circulating the evaporator 110 (S3), neutralization by mixing the acidified distilled water and seawater and discharged to the outside of the desalination plant Step (S4), after all the acidified distilled water is discharged through the washing and rinsing step (S5) to circulate the sea water to wash the evaporator 110 so that a quick and smooth washing The.

Figure 3a is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the distilled water injection step, in the above-described distilled water injection step (S1) of the evaporator 110 composed of a heat recovery section (110a) and the heat shield section (110b). Filling the distilled water in each stage 111, first of all discharged seawater and concentrated brine filled in the desalination plant, and then fresh water produced by the desalination plant as shown and stored separately stored (fresh water) When backflow by using the pump 160 to be introduced into the heat shield section 110b, the distilled water is introduced into the heat recovery section 110a through a pipe between the heat shield section 110b and the heat recovery section 110a, and the evaporator. All of the interior of 110 is filled with distilled water to complete the primary preparation for acid washing.

Figure 3b is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the circulation and heating step (S2), after all the distilled water is filled in the evaporator 110 through the above-described distilled water injection step (S1) The condenser 112 of the stage 111 disposed in the heat recovery section 110a via the evaporation chamber 114 of the stage 111 disposed in the heat shield section 110b by operating the circulation pump 150 and Through the brine heater 120 and the evaporation chamber 114 of the heat recovery section 110a in turn to be repeatedly circulated.

At this time, it is preferable to supply low pressure steam (about 105 ° C., 1.2Bar) to the above-described concentrated brine heater 120 so that distilled water is heated, so that a smooth washing operation by high temperature distilled water can be performed.

Figure 3c is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the acidic liquid injection step (S3), after the distilled water is heated to an appropriate temperature for washing through the above-described circulation and heating step (S2) Opening and closing valve 203 for supplying, and operating the transfer pump 202 so that the acidic liquid stored in the acidic liquid storage tank 201 is added to and mixed with the distilled water circulated to make the distilled water acidic.

Accordingly, the acidified distilled water can circulate inside the evaporator 110 to wash various foreign matters accumulated in the evaporator 110.

In addition, in the acidic solution injection step (S3), in order to maintain the pH concentration of the distilled water properly, it is preferable to inject the acidic solution intermittently, while the acidic solution is injected, the evaporator 110 at a predetermined time interval about 10 minutes. It is desirable to prevent the pH value of the distilled water from being excessively increased by checking the pH concentration of the distilled water circulating), and after the acidic solution is injected, calcium ions (Ca ++) and copper ions (Cu ++) are added every 30 to By checking at intervals of 60 minutes, it is preferable to prevent damage of the evaporator 110 by calcium ions and copper ions.

In addition, in the acidic liquid injection step (S3), it is preferable to minimize the corrosion and damage of the pipe by the acidic liquid by allowing the acidic liquid and the corrosion inhibitor to prevent corrosion of the pipe at the same time to be injected and mixed with distilled water, acidic In the liquid injection step, it is preferable to open all the ventilation valves installed in the evaporator 110 so that the air and carbon dioxide contained in the distilled water are completely discharged to the outside of the evaporator 110 so that the washing can be performed smoothly.

Figure 3d is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the neutralization step (S4), after the cleaning of the evaporator 110 through the above-described acidic liquid injection step (S3) is completed, the heat shield section (110b) Seawater is introduced to neutralize the distilled water, and the neutralizing step (S4) is performed to completely discharge the neutralized distilled water to the outside of the desalination plant.

In the neutralization step (S4) by allowing the seawater to enter the inside of the evaporator 110 through the seawater inlet of the desalination equipment in the state of distilled water, acidified distilled water is mixed with the seawater to gradually neutralize the acidity, At the same time, by operating the concentrated brine discharge pump 170 connected in the heat shield section 110b to allow the mixed water of distilled water and sea water circulating inside the evaporator 110 to be discharged to the outside of the desalination plant, and this operation is performed for a predetermined time. By sustaining for a while, the acidified distilled water is completely discharged from the desalination plant to prevent further corrosion of the desalination plant and contamination of fresh water produced at the desalination plant.

In addition, after the neutralization step (S4) is completed and the acidified distilled water is completely discharged, only the seawater is introduced into the evaporator 110 and then circulated to the residue of foreign matter remaining in the evaporator 110 and the residual of the acidic liquid By proceeding the washing and rinsing step (S5) so that the water can be completely removed, it is preferable to complete the washing of the evaporator (110).

1 is a schematic circuit diagram of a multi-stage evaporative desalination plant according to an embodiment of the present invention.

Figure 2 is a block diagram showing an acid washing method of a multi-stage evaporative desalination plant according to the present invention.

Figure 3 shows the acid washing process of the multi-stage evaporative desalination plant according to the present invention,

   Figure 3a is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the distilled water injection step,

   Figure 3b is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the circulation and heating stages,

   Figure 3c is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the acidic liquid injection step,

   Figure 3d is a schematic circuit diagram of a multi-stage evaporative desalination plant showing the operating state of the neutralization step.

Figure 4 is a schematic circuit diagram showing an example of a conventional multi-stage evaporative desalination plant.

※ Explanation of codes for main parts of drawing

110: evaporator 110a: heat recovery section

110b: train section 111: stage

112 condenser 114 evaporation chamber

120: concentrated brine heater 150: concentrated brine circulation pump

160: fresh water pump 170: concentrated salt discharge pump

200: acid washing device

   201: acidic liquid storage tank 202: transfer pump

   203: on-off valve 204: corrosion inhibitor storage tank

Claims (5)

delete In the multi-stage evaporative desalination plant equipped with an evaporator 110 divided into a heat recovery section 110a and a heat shield section 110b, An acidic liquid storage tank 201 connected to a pipe for discharging concentrated brine of the thermal barrier section 110b and injecting an acidic liquid into the evaporator 110; A transfer pump 202 for forcibly transferring the acidic liquid from the acidic liquid storage tank 201 to a pipe for discharging the concentrated brine; Includes; opening and closing valve 203 for opening and closing the transfer of the acid solution of the acid solution storage tank 201, Acid of the multi-stage evaporative desalination plant further comprises a corrosion inhibitor storage tank 204 for supplying and mixing the corrosion inhibitor for inhibiting the corrosion of the pipe to the acid liquid discharged from the acidic liquid storage tank 201. Washing device. An evaporator 110 divided into a heat recovery section 110a and a heat shield section 110b is provided, and a concentrated brine heater 120 for heating concentrated brine circulating inside the evaporator 110 using high temperature steam. In the acid washing method of the multi-stage evaporative desalination plant equipped with Distilled water injection step (S1) of filling distilled water into the heat recovery section (110a) and the heat shield section (110b); Distilled water injected in the distilled water injection step (S1) by operating one or more concentrated brine circulation pump 150 disposed between the heat recovery section (110a) and the heat shield section (110b) to the inside of the multi-stage evaporative desalination plant. At the same time, the circulation and heating step (S2) for heating the distilled water by supplying hot steam to the concentrated brine heater (120); An acid solution injection step (S3) of injecting and mixing an acid solution into distilled water circulating between the heat recovery section (110a) and the heat shield section (110b); After acidified distilled water circulates between the heat recovery section 110a and the heat shield section 110b for a predetermined time, the sea water is introduced into the heat shield section 110b to neutralize the acidified distilled water, and the inside of the evaporator 110 is removed. Neutralization step (S4) for discharging the neutralized distilled water to the outside of the desalination plant while washing; Washing and rinsing (S5) of washing the evaporator 110 by circulating the seawater after the distilled water and the acidic liquid are completely discharged; Acid washing method of a multi-stage evaporative desalination plant comprising a. The method of claim 3, wherein In the acidic solution injection step (S3), the acid washing method of the multi-stage evaporative desalination plant, characterized in that the corrosion inhibitor to prevent corrosion of the pipe is injected at the same time. The method of claim 4, wherein In the acidic liquid injection step (S3), the acid washing method of the multi-stage evaporative desalination plant, characterized in that all the ventilation valves installed in the evaporator 110 is opened so that air and carbon dioxide is completely discharged to the outside of the evaporator (110). .

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