Membrane filtration system

Patent metadata

Field	Value
Publication number	US-9932250-B2
Application number	US-201514860525-A
Country	US
Kind code	B2
Filing date	Sep 21, 2015
Priority date	Sep 15, 2010
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

According to one embodiment, a membrane filtration system includes a raw water tank, a pretreatment membrane module, a raw water feed line, a high-pressure RO membrane module, a high-pressure line, a preceding power recovery unit which pressurize the pretreated water by transmitting the pressure of the concentrate to the pretreated water, a succeeding power recovery unit which pressurize the raw water by transmitting a remaining pressure of the concentrate to the raw water, a concentrate discharge line, a first pressure transmission line communicating to the power recovery unit by being branched from the high-pressure line, a second pressure transmission line communicating to the power recovery unit by being branched from the raw water feed line, and a valve provided in the drain line to regulate a discharge of the concentrate from the power recovery unit in accordance with a pressure loss in the pretreatment membrane module.

First claim

What is claimed is:

1. A membrane filtration system, comprising:
a raw water tank configured to accommodate a raw water containing solutes and insoluble components;
a pretreatment membrane module that separates and removes the insoluble components from the raw water fed from the raw water tank;
a raw water feed line having a raw water feed pump to feed the raw water from the raw water tank to the pretreatment membrane module;
a high-pressure reverse osmosis membrane module provided in downstream of the pretreatment membrane module to separate and remove the solutes from pretreated water providing treated water as permeate and concentrate as retentate;
a low-pressure reverse osmosis membrane module provided in downstream of the high-pressure reverse osmosis membrane module and to which a pressure lower than that applied to the high-pressure reverse osmosis membrane module is applied to separate and remove remaining solutes from the treated water;
a high-pressure line having a high-pressure pump to feed the pretreated water to the high-pressure reverse osmosis membrane module at a predetermined high pressure;
a preceding power recovery unit having a positive-displacement pump to which a portion of each of brine and the pretreated water are fed and which pressurize the pretreated water by transmitting pressure of the concentrate to the pretreated water;
a succeeding power recovery unit having a positive-displacement pump to which a portion of each of the concentrate from the preceding power recovery unit and the raw water are fed and which pressurize the raw water by transmitting a remaining pressure of the concentrate to the raw water;
a concentrate discharge line through which the concentrate discharged from the high-pressure reverse osmosis membrane module flows to transmit pressure of the discharged concentrate to the positive-displacement pump of the preceding power recovery unit;
a communicating line communicating the preceding power recovery unit and the succeeding power recovery unit and through which the concentrate from the preceding power recovery unit flows;
a first pressure transmission line branched from the high-pressure line and communicating to the preceding power recovery unit and through which a portion of the pretreated water to be fed to the high-pressure reverse osmosis membrane module flows;
a second pressure transmission line branched from the raw water feed line and communicating to the succeeding power recovery unit and through which a portion of the raw water to be fed to the pretreatment membrane module flows;
a drain line to discharge the concentrate from the succeeding power recovery unit;
a pressure regulating valve provided in the drain line to regulate a discharge of the concentrate from the succeeding power recovery unit in accordance with a pressure loss in the pretreatment membrane module;
a treated water tank arranged in a subsequent stage of the pretreatment membrane module to accommodate the pretreated water having passed through the pretreatment membrane module;
a water conveyance line having a conveying pump to feed the pretreated water from the treated water tank to the high-pressure pump; and
a back washing line branched from the water conveyance line between a downstream side of the conveying pump and the high-pressure pump, and communicating to the pretreatment membrane module, to guide the pretreated water that feeds to the high-pressure pump to the pretreatment membrane module by driving of the conveying pump,
wherein the pretreatment membrane module generates the pretreated water, which is processed by the high-pressure reverse osmosis membrane module to provide the treated water.

2. The system according to claim 1 , further comprising:
a first manometer that measures a pressure upstream of the pretreatment membrane module;
a second manometer that measures a pressure downstream of the pretreatment membrane module; and
a controller that determines a membrane differential pressure ΔP of the pretreatment membrane module from measured pressures of the first and second manometers, regulates the pressure of the concentrate discharged from the high-pressure reverse osmosis membrane module by opening the pressure regulating valve if the determined membrane differential pressure ΔP is smaller than or equal to a set pressure value Pc, and maintains the pressure regulating valve closed if the determined membrane differential pressure ΔP is larger than the set pressure value Pc.

Assignees

• Toshiba Kk

Inventors

• Matsushiro Takeshi
• Yokokawa Katsuya
• Kurokawa Futoshi
• Namba Ryo
• Matsui Koichi
• Yamagata Hideaki
• Hiraga Yuka
• Murayama Seiichi
• Tokimoto Hiroyuki

Classifications

• B01D61/10

  Accessories; Auxiliary operations · CPC title

• B01D61/58

  Multistep processes · CPC title

• B01D61/022

  Operations & Transport · mapped topic

• C02F2103/06

  Contaminated groundwater or leachate · CPC title

• C02F1/444

  by ultrafiltration or microfiltration · CPC title