Principle of reverse osmosis equipment

The reverse osmosis device produces 70m of water at an inlet temperature of 25 ℃3/h， The recovery rate is 75%, and the initial desalination rate is 98%. The reverse osmosis device is equipped with a low-pressure flushing function when it is turned on. When the reverse osmosis device is turned on, the raw water pump is first used to perform low-pressure flushing on the RO device to exhaust the air inside the RO membrane and membrane shell, and then the high-pressure pump is started to produce water; The reverse osmosis device is designed to run continuously for 2 hours and perform a low-pressure flushing on the RO membrane. Before the scale impurities on the concentrated water side of the RO membrane become solid, they are flushed out and discharged from the RO membrane; Perform concentrated water replacement during shutdown, using RO produced water to replace the concentrated water inside the RO membrane, preventing impurities on the concentrated water side from settling on the surface of the RO membrane during shutdown. At the same time, taking advantage of the corrosive nature of RO produced water, trace scale substances deposited on the surface of the RO membrane can be soaked off. All of these low-pressure flushing and concentrated water replacement are aimed at timely removal of impurities such as inorganic salts and bacteria, preventing their deposition on the surface of the RO membrane, reducing the cleaning frequency of membrane components, and slowing down the degradation of performance parameters such as water production and desalination rate. The low-pressure flushing and concentrated water replacement are carried out automatically.

Reverse osmosis instructions

1、 Reverse osmosis equipmenttechnological process

Raw water → Raw water tank → Raw water pump → (fungicide dosing) → Quartz sand filter → Activated carbon filter → (scale inhibitor dosing) → 5 μ security filter → High pressure pump → Primary reverse osmosis device → Intermediate water tank → Secondary reverse osmosis device → Secondary pure water tank

2、 Introduction to Reverse Osmosis Equipment Process

1Raw water tank (box)

Cache raw water

2. Boosting pump

Supply pre-processing system to provide pressure

3、Quartz sandfilter：

Quartz sand filters mainly use appropriately graded quartz sand and operate at a suitable filtration rate to remove impurities such as sediment, suspended solids, colloids, etc. from raw water, reduce the SDI (Pollution Index) value, preliminarily purify the raw water, reduce the turbidity of the incoming water, and ensure the SDI (Pollution Index) of the filtered effluent15≤ 4, meet the water inlet requirements for subsequent equipment.

4activated carbonfilter：

Activated carbon is made by activating carbon containing substances such as wood, coal, and fruit shells (cores) through chemical or physical methods. It has a large number of micropores and a huge specific surface area, thus possessing strong physical adsorption ability and effectively adsorbing organic pollutants in water. In addition, during the activation process, some oxygen-containing functional groups are formed on the non crystalline parts of the activated carbon surface, which enable the activated carbon to have chemical adsorption and catalytic oxidation and reduction properties, effectively removing some metal ions from water. Activated carbon filters mainly remove some organic matter and free residual chlorine from water.

5、Add scale inhibitorDevice:

The system uses a certain amount of scale inhibitor to prevent dissolved solids such as sulfates, carbonates, silica, etc. on the concentrated water side of the RO membrane element from scaling on the surface of the RO membrane while selecting to pass through fresh water, which affects the performance of the RO membrane.

Our company suggests adding a high-efficiency scale inhibitor specifically designed for reverse osmosis to the system. This type of scale inhibitor has an LSI index of 2.5 on the concentrated water side of reverse osmosis and will not cause scaling of hardness ions due to concentration.

The scale inhibitor device consists of a metering pump and a dosing tank. The metering pump is produced by Milton Roy Company in the United States and runs smoothly, stably, and accurately. The dosage and preparation of the medication need to be manually operated.

6Security filter：

In order to ensure that the reverse osmosis membrane components are not damaged by fine particulate impurities and affect the effluent volume of reverse osmosis, the system is equipped with a security filter, which contains a polypropylene filter element with a filtration accuracy of 5.0 μ m and a stainless steel shell structure.

7、high-pressure pump

In order to overcome the osmotic pressure of the RO membrane, external pressure needs to be provided to the RO membrane, which is the pressure required for the normal operation of the RO membrane. This pressure is provided by a high-pressure pump. This system uses a high-pressure pump from the south, which has a SUS304 stainless steel structure for its flow components. It has the characteristics of small volume, high efficiency, and low noise.

8. Reverse osmosis membrane

The membrane element of the reverse osmosis device is made of polyamide composite membrane provided by Dow Chemical Company in the United States. The element is composed of three layers of thin film composite, with a surface layer of aromatic polyamide material and a thickness of about 2000 angstroms. It is supported by a layer of microporous polysulfone, which can withstand high pressure and has good resistance to mechanical tension and chemical erosion. The element has a relatively large water production flux and is resistant to NaCl and CaCl2、 MgCl2Has a removal rate of over 99%.

9、Reverse osmosis membrane shell

The membrane pressure vessel adopts fiberglass pressure membrane tubes specially designed for roll type RO components. Pressure resistant to 300psi, smooth inner wall, easy to install and remove

10Auxiliary configuration of reverse osmosis device:

The reverse osmosis device is equipped with electric butterfly valves, automatic fast flushing discharge valves, and automatic concentrated water replacement valves. Stainless steel valves and fittings are used for the high-pressure pump. The reverse osmosis device is also equipped with flow meters, conductivity meters, pressure gauges, and other indicators to monitor the operating conditions of the RO device. Each set is equipped with a sampling valve and a centralized sampling plate, which can be used to sample and detect water quality at any time.

11Electrical specifications：

（1）All low-voltage power distribution panels use GGD2 type distribution panels.

（2）Control of proportioning and dosing

This system controls the start and stop of the corresponding metering pump based on the corresponding pre-treatment system and reverse osmosis system, thereby achieving quantitative dosing. The metering pumps for fungicides, reducing agents, and scale inhibitors are interlocked with the corresponding process flow pumps for start and stop.

（3）Preprocessing filter control

The start-up and operation process of the device are automatically controlled by PLC. At the same time, a local instrument panel and a local operation panel are set up, where relevant process parameters can be read out and relevant water pumps and automatic valves can be operated on the local operation panel. Online detection instruments are installed for important parameters such as flow rate..

（4）Reverse osmosis system (RO) control

The RO system is also equipped with a local instrument panel and a local operation panel, where relevant process parameters of the RO can be read out, such as conductivity, flow rate, etc ORP、 Pressure, etc; And it can start and stop the RO inlet high-pressure pump and related automatic valves on the local operation panel. Online detection instruments are installed for important parameters such as conductivity, flow rate, ORP, etc., and an over limit alarm function is set.

（5）Reverse osmosis (RO) start stop protection

When the RO is put into operation, in order to prevent the high-pressure pump from suddenly starting to increase pressure and causing high-pressure impact on the RO membrane components, a slow opening valve is set between the outlet of the high-pressure pump of the RO device and the RO membrane components. The valve is controlled by a programmable logic controller (PLC) to gradually increase the pressure of the reverse osmosis membrane components to a certain level. When the RO is stopped, rinse the RO membrane components automatically with RO product water for about 3-5 minutes to avoid the deposition and scaling of high concentration salts in concentrated water on the surface of the RO membrane, which may affect its performance.