Claims:We Claim:
1) A seawater desalination treatment system (100), comprising:
a pre-treatment section (20) configured to receive seawater for pre-filtration; and
an intake section (10) consisting of an intake head (5) configured to receive the pre-filtered seawater for dislodging of deposits therefrom in a series of cleaning steps, wherein the cleaning steps comprises of disinfection for a predetermined time coupled with backwash at a predetermined flow rate for a predefined time period.

2) The seawater desalination treatment system (100), as claimed in claim 1, wherein the disinfection comprises of treatment with sodium hypochlorite or chlorine of concentration ranging between 5-50ppm.

3) The seawater desalination treatment system (100), as claimed in claim 1, wherein the predetermined time period for disinfection is between 1-20 min.

4) The seawater desalination treatment system (100), as claimed in claim 1, wherein the disinfection is followed by soaking for about 1-60 min prior to the backwash.

5) The seawater desalination treatment system (100), as claimed in claim 1, wherein the backwash comprises of high-pressure cleaning in the reverse direction post the disinfection at the flow rate of 2-4 times intake flow.

6) The seawater desalination treatment system (100), as claimed in claim 1, wherein the predefined time period for the backwash is between 1-60 min.

7) The seawater desalination treatment system (100), as claimed in claim 1, wherein the intake section (10) comprises of an intake pipe of varying diameter between 300mm to 1500mm to draw the seawater.

8) The seawater desalination treatment system (100), as claimed in claim 1, wherein the pre-treatment section (20) is configured to receive the seawater for pre-filtration using auto self-cleaning filter and multigrade or a sand filter.

9) The seawater desalination treatment system (100), as claimed in claim 1, wherein the intake section (10) is flushed with the pre-filtered seawater at a flow rate of 2-4 times intake flow for 1-60 min.

10) The seawater desalination treatment system (100), as claimed in claim 1, wherein a pH between 1-5 is maintained for 1-60 min during the backwash.
, Description:FIELD OF INVENTION

[0001] The present invention is directed to fouling prevention system and method, and more particularly to an in-situ fouling prevention method in the intake system of seawater desalination plant.

BACKGROUND OF INVENTION

[0002] The intakes of the seawater desalination plants are frequently prone to failures due to a decrease in the seawater flow through the intake system to the plant predominantly due to fouling problems. During the operation of the seawater desalination system both the inorganic and organic matter tend to settle over some time and also form a scale thereon. As a result of this phenomenon, the flow of seawater through the intake gets reduced gradually, and affects the capacity of the plant. Therefore, the intake system has to be frequently cleaned manually to maintain the flow and capacity of the plant. However, frequent cleaning results in the loss of production and also increases the maintenance cost, which remains a challenge for this industry.
[0003]In a conventional seawater desalination plant, the intake system is periodically cleaned manually during annual or bi-annual shutdowns. Cleaning of the intake calls for professional divers and support manpower, which is expensive and time-consuming. Hence, to operate the seawater desalination plant at optimum capacity throughout the year, a Clean-in-Place system is necessary as the water produced from these plants is necessary for a continuous supply of water to industries / domestic purposes. Though the existing seawater desalination plants have a dosage of chlorine to prevent/ remove the biofouling, it is not effective in removing the inorganic and organic debris that gets settled on the intake pipe.
[0004] Thus, none of the contemporary solutions are capable of minimizing this fouling at cost effective measures. In the background of foregoing limitations, there exists a need for a system and method which is capable of preventing fouling in intake system of seawater desalination plant at optimum capacity and enhanced efficacy.
OBJECT OF THE INVENTION

[0005] The primary objective of the present disclosure is to provide a system and method for prevention of biological and inorganic fouling in intake system of a seawater desalination plant.
[0006] In one other objective of the present disclosure, a sustainable solution for preventing fouling in seawater desalination is proposed.
[0007] Another objective of the present disclosure is to provide an economic and cost –effective system and method of preventing fouling in seawater desalination at reduced maintenance cost.
[0008] Another objective of this disclosure is to develop an in situ cleaning process of the intake system in a seawater desalination plant.
[0009] Another objective of this disclosure is to provide an automated system and method for prevention of fouling in the intake system of a seawater desalination plant.
[0010] In yet another objective of the present disclosure, an efficient process of reducing scaling of deposited biomass and other inorganic foulants on the pipes of system is provided.
SUMMARY OF THE INVENTION

[0011] The present invention is directed to a seawater desalination treatment system comprising of a pre-treatment section configured to receive seawater for pre-filtration; and an intake section consisting of an intake head configured to receive the pre-filtered seawater for dislodging of deposits therefrom in a series of cleaning steps, wherein the cleaning steps comprises of disinfection for a predetermined time coupled with backwash at a predetermined flow rate for a predefined time period.

[0012] These and other aspects, features and advantages of the present invention will be described or become apparent from the following detailed description of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Fig. 1 is a seawater desalination treatment system, in accordance with one exemplary embodiment of present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] Before the present phenomenon of fouling prevention system and method in a seawater desalination plant is described, it is to be understood that this disclosure is not limited to the particular system and method for achieving so, as described, since it may vary within the specification indicated. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present invention, which will be limited only by the appended claims. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. The disclosed embodiments are merely exemplary methods of the invention, which may be embodied in various forms.
[0015] In accordance with one general embodiment of present disclosure, and as shown in Fig. 1, the seawater desalination plant 100 comprises three main stages namely a) Intake section10 b) Pre-treatment section 20, and c) Seawater Reverse Osmosis section 30. The intake section 10 is the heart of any seawater desalination system 100 with which the seawater 1 is drawn for treatment and usage. Hence, for the successful operation of the seawater desalination plant, the performance of the intake section 10 at optimum efficiency is required.
[0016] As commonly known, seawater 1 contains many faunal and floral entities including inorganic matter. To prevent these particles from entering into the intake section 10, an intake head 5 with a sieve 7 made of exotic metal is provided in accordance with one specific embodiment of present disclosure. As discussed in aforementioned sections, during the operation of the intake section 10, the inorganic and organic matter tend to settle and also form a scale on the intake head 5 and the intake pipe 6. As a result of this phenomenon, the flow of seawater through the intake section 10 gets reduced gradually, impairing efficient treatment of seawater.
[0017] In accordance with one general embodiment of present disclosure, a mechanical system with a cleaning protocol is developed to frequently flush to disinfect and remove all the deposited biomass/ fauna and flora and other inorganic foulants, such as silica and scales formed in the pipes and on the intake head 5 placed on the sea bed. In accordance with one preferred embodiment of present disclosure, the modified system of cleaning disinfects and dislodges the deposits on the intake head 5 through a sequence of cleaning steps. First is the initiation step of disinfection with sodium hypochlorite or chlorine followed by high-pressure cleaning in the reverse direction (backwash). The disinfection step coupled with a fast backwash will render the pores of the intake sieve 7 clean. This Cleaning-in-Place (CIP) will be followed at regular intervals to maintain efficacy of the intake section 10.
[0018] In one working embodiment of present disclosure, the seawater is drawn from sea through an intake section 10. Referring to Fig. 1, it can be seen that an HDPE (high-density polyethylene) pipe6 of varying diameter (300 mm to 1500 mm) draws the seawater to the pump suction 8 from where it is pumped to the desalination plant for further processing. The direction of the flow of water in the intake section10 will be from the sea to the desalination plant. The intake head 5 will be placed on the seabed 2 at about 1– 2 km from the shore 3. The intake head 5 is designed with a sieve 7 for preventing the fish and other living organisms from entering the intake section 10. Since the sea is rich in micro-nutrients there is every possibility of excessive bio-growth which has to be prevented or removed frequently to avoid fouling.
[0019] In the existing plants, chlorine in the form of hypochlorite is dosed to prevent biological growth, but the sediments and other inorganic matter will remain and gets accumulated over some time on the intake head 5. This accumulated inorganic and organic debris will reduce the flow and has to be manually cleaned to retain the flow and efficiency of the system 100.
[0020] In present disclosure, an in-situ cleaning process of the intake section 10 through a method of step-wise backwash system, is conceptualized. In one general embodiment, the intake section 10is backwashed at the desired flow rate with sodium hypochlorite of concentration ranging from 5 – 50 ppm through a dosing line 4, followed with a filtered water backwash at the desired flow rate through a backwash line 9, so that the fouling and debris settled on the intake head gets dislodged, thus cleaning the entire system 100 and maintaining the seawater flow without any manual intervention.
[0021] This system first disinfects coupled with rigorous flushing to dislodge the debris settled on the intake section 10. The highlighted portion of the pipeline shown in Fig.1 is the new mechanism introduced at the intake section 10 before the intake pump 8. Through this pipe 6, filtered water from the filtered water tank in the RO plant 15 will be pumped at high velocity along with hypochlorite to clean both the bio-fouling /scales sticking on the intake section 10 and inorganic and organic debris settled in the intake pipe 6 and the intake head 5. Precisely, the filtered water from the RO pretreatment section is pumped into the intake pipe 6 before the intake pump 8 in a reverse direction at a predetermined flow rate. This cleaning protocol involves a six-step process.
[0022] Since the system is a CIP process, cleaning can be done online without shutting down the plant, thus providing a method for the intake section 10 to operate at the optimum efficiency without manual intervention for cleaning and plant shutdowns. The system efficiency is maintained and also much of maintenance cost is saved. A system of backwashing the intake pipe 6 and the intake head 5 with a backwashing protocol is developed. Filtered water in the pre-treatment section 20 of the desalination plant is obtained after passing the seawater through an auto self-cleaning filter 11 and the multigrade or sand filter 12. This filtered water is collected in a storage tank 13. Filtered water is pumped at a flow rate of 2 – 4 times the intake flow through the intake pipe 6 before the intake pump 8 as shown in Fig.1. Filtered water will be pumped at a higher flow rate thus dislodging all the settled material in the intake pipe 6 and the intake head 5. The sequence of cleaning in place protocol will be as follows:
[0023] 1. Flushing the intake line with filtered water at a flow rate of 2 – 4 times the intake flow for 1 – 60 minutes.
2. Flushing the line with 5 – 50 ppm of sodium hypochlorite for 1 – 20 minutes.
3. Stop the flushing and soaking for about 1 – 60 minutes.
4. Flushing the line with filtered water at a flow rate of 2 – 4 times the intake flow for 1 – 60 minutes.
5. A low pH: 1 – 5 flushing for about 1 – 60 minutes.
6. Flushing the line with filtered water at a flow rate of 2 – 4 times the intake flow for 1– 60 minutes.
[0024] The above steps of cleaning can be done at one stretch or in a separate sequence of Steps [1,2,3,4] or [4,5,6] depending on the extent of the fouling of the organic and inorganic fouling in the intake pipeline. In one specific embodiment, the flushing line is connected before the intake pipe 6 and process is performed before the intake pump 8. Preferably, a valve is provided to prevent the backwash flow into the intake pump 8.
[0025]The foregoing description is a specific embodiment of the present disclosure. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.