Method of Filtering Water

Patent metadata

Field	Value
Publication number	US-2019169050-A1
Application number	US-201716319328-A
Country	US
Kind code	A1
Filing date	Jul 11, 2017
Priority date	Jul 21, 2016
Publication date	Jun 6, 2019
Grant date	—

Abstract

A method of operating a filtration unit of a filtration system includes
feeding, during filtration, feed water containing suspended particulate material to an inside of each of a plurality of hollow fibres through a first inlet and a second inlet of each hollow fibre while simultaneously removing a filtrate from an outside of each of the hollow fibres through an outlet of a filtration elements. In addition, the method includes feeding, during back-washing, back-wash water to the outside of the hollow fibres through the outlet of the filtration element. Further the method includes discharging, in a first back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres from one end thereof. Still further, the method includes discharging, in a second back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres from the other end thereof.

First claim

1 . A method of operating a filtration system, the method comprising:
feeding, during filtration, feed water containing suspended particulate material to an inside of each of a plurality of hollow fibres through a first inlet of each of the hollow fibres and a second inlet of each of the hollow fibres while simultaneously removing filtrate from an outside of the hollow fibres through an outlet of at least one filtration element, wherein a filtration system comprises at least one filtration unit including a filtration vessel containing the at least one nitration element wherein the at least one filtration element comprises a plurality of the hollow fibres, wherein each hollow fibre has a first inlet at a first end thereof and a second inlet at a second end thereof, wherein the first inlet and the first outlet of each hollow fibre is in fluid communication with the inside of the hollow fibre, and wherein the outlet of the at least one filtration element is in fluid communication with the outside of the hollow fibres; and feeding, during back-washing, back-wash water to the outside of the hollow fibres through the outlet of the at least one filtration element; discharging, in a first back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres through the first inlets thereof; and, discharging, in a second back-wash cycle, back-wash water containing entrained particulate material from the inside of the hollow fibres through the second inlets thereof, wherein the first and second back-wash cycles may be performed sequentially in either order.

2 . The method of claim 1 , wherein the at least one filtration element has a first outlet and a second outlet arranged at a first end and a second end, respectively, thereof; and, during filtration, removing filtrate from the outside of the hollow fibres simultaneously through both the first and second outlets of the at least one filtration element.

3 . The method of claim 1 , wherein the filtration vessel of the at least one filtration unit contains a plurality of filtration elements each having a first and a second back-wash cycle, and performing the back-wash cycles for the plurality of filtration elements sequentially in any order.

4 . The method of claim 3 , wherein the filtration vessel of the at least one filtration unit contains a first filtration element having a first and a second back-wash cycle (Cycles A and B) and a second filtration element having a first and a second back-wash cycle (Cycles C and D) and:
(i) in Cycle A, feeding the back-wash water to the outlet of the first filtration element and removing back-wash water containing entrained particulates from the first inlets of the first filtration element; (ii) in Cycle B, feeding the back-wash water to the outlet of the first filtration element and removing back-wash water containing entrained particulates from the second inlets of the first filtration element; (iii) in Cycle C, feeding the back-wash water to the outlet of the second filtration element and removing back-wash water containing entrained particulates from the first inlets of the second filtration element; and, (iv) in Cycle D, feeding the back-wash water to the outlet of the second filtration unit and removing back-wash water containing entrained particulate from the second inlets of the second filtration element; and, wherein performing Cycles A to D is effected sequentially in any order.

5 . The method of claim 1 , wherein the filtration vessel contains a plurality of filtration elements each having a first back-wash cycle and a second back-wash cycle, and performing the first back-wash cycles for each of the filtration elements simultaneously and performing the second back-wash cycles for each of the filtration elements simultaneously, in either order.

6 . The method of claim 1 , wherein the filtration vessel contains from four to twelve filtration elements each having a first and a second back-wash cycle, and backwashing the filtration elements in two or more subsets each subset comprising at least two filtration elements and backwashing the two or more subsets are successively in any order by performing the first back-wash cycles for each subset of filtration elements simultaneously and performing the second back-wash cycles for each subset of filtration elements simultaneously in either order.

7 . The method of claim 1 , wherein the filtration system comprises a plurality of filtration units and the filtration vessels of the plurality of filtration units each contain a plurality of filtration elements located at first, second and optional successive positions in the filtration vessels, each filtration element having first and second back-wash cycles, and wherein some or all of the filtration units are back-washed by performing:
the first back-wash cycles for the filtration elements located at the first positions of the filtration vessels simultaneously; the second back-wash cycles for the filtration elements located at the first positions of the filtration vessels simultaneously; the first back-wash cycles for the filtration elements located at the second positions of the filtration vessels simultaneously; the second back-wash cycles for the filtration elements located at the second positions of the filtration vessels simultaneously; the first back-wash cycles for the filtration elements located at the or each optional successive positions of the filtration vessels simultaneously; and the second back-wash cycles for the filtration elements located at the or each optional successive positions of the filtration vessels simultaneously; wherein the simultaneous back-wash cycles for the elements located at the first, second and optional successive positions in the filtration vessels are performed sequentially in any order.

8 . The method of claim 7 , further comprising back-washing of the filtration element of each filtration unit every 50 to 60 minutes.

9 . The method of claim 7 , wherein, during filtration, providing the feed water for the plurality of filtration unit at a pressure in the range of 2 to 10 bar gauge, preferably, 2.5 to 5.5 bar gauge and at a flow rate of feed water to the first and second inlets of the hollow fibres of each of the plurality of filtration elements in the range of 1.4 to 2.5 m 3 /hour.

10 . The method of claim 9 , further comprising, during back-washing, providing the back-wash water for the at least one filtration unit at a pressure in the range of 1.5 to 3.0 bar gauge and a flow rate of the back-wash water to the at least one filtration element during either the first back-wash cycle or the second back-wash cycle in the range of 40 to 50 m 3 /hour.

11 . The method of claim 7 , wherein the plurality of the filtration units are arranged in a rack comprising two or more banks of filtration units and the banks of filtration units are back-washed sequentially in any order.

12 . The method of claim 1 , further comprising periodically adding at least one cleaning chemical to the back-wash water, wherein the cleaning chemical is selected from: (1) acids such as organic acids (in particular citric acid) or protic acids (in particular, hydrochloric acid) for removing inorganic mineral scales from the filtration system; (2) bases such as sodium hydroxide or potassium hydroxide that target organic species that foul the membrane; (3) oxidants or disinfectants such as sodium hypochlorite, chlorine gas or hydrogen peroxide for removing organic materials or biofilms from the membranes; and, (4) surfactants to remove organic materials and inert particles from the membranes.

13 . A filtration unit comprising

Assignees

• Bp Exploration Operating Co Ltd

Inventors

• Crouch John Henry
• Lomax James
• Williams John Dale

Classifications

• B01D61/18

  Apparatus therefor · CPC title

• B01D2315/20

  Operation control schemes defined by a periodically repeated sequence comprising filtration cycles combined with cleaning or gas supply, e.g. aeration · CPC title

• B01D2315/08

  Fully permeating type; Dead-end filtration · CPC title

• B01D2317/04

  Elements in parallel · CPC title

• B01D2321/04

  Backflushing · CPC title