For the technology related to 300,000 tons of caustic soda and brine, which is better: Pohr or Kemfilm?

The basic processes for forming pores and removing films are similar; just use the cheaper option

Both processes have their advantages and disadvantages. In terms of process maturity and the number of manufacturers using them, Kay Membrane has an edge. However, the use of a particular technology depends on various factors such as skill level and the ability to control the process; therefore, multiple considerations are needed when making a choice, and it depends on what the user prioritizes. Kai membrane filtration technology (1) Pre-reaction. The pre-reaction mainly removes Mg2+ and most of the Ca2+ from the brine. NaOH, Na2CO3 are added to the reactor respectively to react with Mg2+ and Ca2+ in brine, forming insoluble Mg(OH)2 and CaCO3 precipitates. To remove Mg2+ completely, the amount of NaOH added must exceed the theoretical requirement; this process calls for an excess of 100–300 mg/L of NaOH. (2) Pretreatment. Various impurities present in the raw salt enter the brine during the salt production process. Natural organic substances such as bacteria, algae, and humic acid in the brine are oxidized by NaClO into smaller molecules, which are then removed in the pre-treatment unit through adsorption and coprecipitation by FeCl3; some insoluble mechanical impurities are also removed at the same time. The brine after the preliminary reaction contains a large amount of Mg(OH)2 precipitate, which appears as gelatinous floccules that are extremely difficult to settle. This also hinders the proper operation of the Kaier membrane filter; therefore, the Mg(OH)2 is removed first using a pretreatment unit. First, the brine is fed into a pressurized dissolved air tank, where the pressure is maintained at 0.18–0.30 MPa; under this pressure, a certain amount of air dissolves in the brine (typically 5 L of air per 1 m3 of brine). When the brine enters the preprocessor, the pressure drops suddenly; the air contained in the brine escapes, resulting in the formation of numerous tiny bubbles. Under the action of the flocculant, these tiny bubbles combine with the mechanical impurities present in the brine to form particles with a lower apparent density, which then rise to the surface of the preprocessor where they form sludge. This sludge is removed at regular intervals through the sludge discharge holes. Some of the particles with higher density sink, forming settled sludge, which is discharged through the sludge outlet holes. The clear liquid flows out from the clear liquid outlet. (3) Post-reaction. When a sodium carbonate solution is added to saltwater, it reacts with the Ca2+ ions in the saltwater to form an insoluble CaCO3 precipitate. The reaction equation is: Ca2+ + CO32- → CaCO3. To remove Ca2+ completely, the amount of sodium carbonate added must exceed the theoretical requirement; in this process, an excess of 300–500 mg/L of sodium carbonate is used. (4) Filter. Brine is passed under certain pressure through membrane bags with a pore size of 0.22–0.50 μm; impurities are trapped, thereby yielding pure concentrated brine. The entire filtration system is automatically controlled via a PLC; based on the quality of the pretreated brine, the operating parameters for the Kaier membrane filter are set as follows: filtration cycle time of 1200–1500 seconds, maximum backwash time of 30 seconds, settling time of 60 seconds, and sludge discharge time of 15 seconds. The filtration cycle is repeated 5 times, and the pickling period is about 10 days (or when the filtration pressure exceeds 0.05 MPa). Pore membrane filtration technology: The pore membrane is a PTFE-based, seamless membrane that is formed through single extrusion; it has a smooth surface, does not stick to surfaces, features a low friction coefficient, and exhibits strong corrosion resistance. All its components are resistant to chlorine corrosion, making it suitable for use in pickling processes. Its pore size is 0.2μm, with a filtration flux of ≥0.5 m3/(m2·h). It can handle water or solutions with a suspended solids concentration of 2.8 g/h, and it possesses hydrophobic properties – that is, it has a low water absorption rate

The process technology is the same; the differences are as follows: the membrane tubes of Kai Membrane have a thickness of 1 mm, with a filtration flux of 0.4 m3/m2. Pre-wetting is required, and they must be kept and transported in a wet state, using titanium flanges； The Porex membrane (an improved version of the Gore membrane) has a membrane tube thickness of 0.5 mm, a filtration flux of 0.5–0.6 m3/m2; it does not require pre-wetting, can be stored and transported in a dry state, and uses CPVC flanges. In terms of usage, there is no difference; the only choices lie in investment and after-sales service. The prices aren’t cheap either.

Use more Kai membranes; they are quite good. Which organization do you work for?

This post was last edited by 181128425 on 2009-8-15 at 13:55. A few days ago, someone from the Xian manufacturer came to me; I found that the technology used was quite good. The investment required is 50% to 60% of that for Kay Membrane systems, and no pre-treater is needed. It enables the simultaneous removal of calcium and magnesium, while sulfate ions still need to be removed in advance. The filtration system features two stages of filtration, with an internal layer of organic molecular sphere filler 1 to 2 millimeters thick, covering a depth of 50 centimeters; this layer floats on top of the filtered saltwater. I’m not sure what the actual performance will be like. It seems that Tianye’s 300,000-ton facility uses this same technology

Is someone upstairs promoting CN Company? Have you tried it yourself? Have you seen it in person? Have you seen the effect in use? Have you seen the CN filters used in all of Tianye’s 300,000 tons of production? **It has been said: Without investigation, there is no right to speak! Can a filtration layer 50 cm thick, composed of organic molecular spheres with a diameter of 1–2 mm (which sound nice, but are actually similar to those small foam particles used in polystyrene insulation materials), achieve the same level of precision as the sand filters that have been used in the past? Don’t forget that there is also a Doul tank in front of the sand filter; this device doesn’t contain anything at all and simply filters out the turbid saltwater. Everyone should also use their brains to think about it, conduct thorough investigations, keep track of the progress of this technology, and then exchange ideas with one another to see if it is possible to meet the requirements for ion-exchange membrane brine. Users from Shandong and Henan can visit Huaxiang Chemical in Xin County, Shandong – it is located near the Second Oil Extraction Plant of the Zhongyuan Oilfield. Users in the south can go and check out Xindong and Jiangdong in Changzhou. Which friend has seen **Tianye’s application in use? Please share your insights here.

What the person from Haiyou upstairs said is correct; I am not optimistic about CN filters. I think the Kaimo membrane technology is more mature, and I support that technology.

Everyone agrees that the accuracy of saltwater treatment using Huawei’s ceramic membrane technology is excellent; the process is quite reasonable. As is the case with any solution, there are advantages and disadvantages. Ceramic membranes require more space and incur higher costs for replacement, which is also acknowledged by everyone. Porcelain membranes take up the least space and have the simplest processing requirements, but barium sulfate can clog the filtration tubes, making it difficult to clean them and thus reducing the filtering area – this fact is also recognized by all

Friend on the seventh floor, have you seen it? Could you give me an introduction? !

Our company is also planning a 300,000-ton ion-exchange membrane caustic soda project, which is currently in the preliminary process research stage. For the brine purification system, we have investigated processes using Kaimo membrane, Gore membrane, CN membrane, ceramic membrane technologies, as well as the Dow sand filtration and carbon tube technology. The carbon tube process has been rejected due to its high operating costs. The organic membrane process has been widely applied, so no further details are provided on it. Overall, it is considered a mature process with stable operation, but it involves high initial investment and high operating costs. We focused our research on the ceramic membrane process and the CN membrane process; we did not inform either manufacturer about this. The preliminary conclusions are as follows: First, both of these new processes simplify the workflow compared to the membrane-based process, enabling the integrated removal of impurities such as calcium and magnesium. They eliminate the floating clarification tank used in the membrane-based process, thereby reducing initial investment costs. Additionally, they address the problems associated with poor control of the floating tanks in some manufacturers’ systems. From a process perspective, these new processes represent an advancement over the membrane-based method ； II. The effluent quality parameters for both the ceramic membrane process and the CN membrane process can meet the requirements for brine water. We have examined the ceramic membrane process used by Hukou Xinkangda and the CN membrane process used by Jintan Jindong, and in both cases the suspended solids level in the effluent is less than 1 MG/L. Furthermore, our sample testing results confirmed the feedback from users. III. In both the ceramic membrane process and the CN membrane process, the operating time of ion exchange membrane caustic soda systems was slightly over two years, less than three years; this is inferior to the operating time and performance achieved by membrane-based processes. For example, the ceramic membrane process at Hukou Xinkangda operated for about two years and five months, while the CN membrane process at Jintan Jindong operated for about two years and two months ； At Hukou Xinkangda, the capacity of ceramic membrane technology is 50,000 tons per year for ion-exchange membrane caustic soda, while at Jintan Jindong, the capacity using CN membrane technology is 150,000 tons per year for ion-exchange membrane caustic soda. Ceramic membrane technology allows for three months longer operation time compared to CN membrane technology, but its capacity is slightly lower. Each of the two has its advantages and disadvantages. IV. The Kaimo process shares similar principles to the Gore process; it is relatively mature and has been used in many applications, so no further details are needed. V. Service life of membrane modules: Organic membranes have a guaranteed service life of 3 years, inorganic ceramic membranes have a guaranteed service life of 5 years, and CN membranes have a guaranteed service life of 6 years ； Kai Membrane now offers membrane cleaning solutions, and the membrane lifespan of some manufacturers can reach 4 years ； Since the operating time of both ceramic membranes and CN membranes is less than 3 years, it is currently not possible to determine their guaranteed lifespan. It is understood that the CN membrane is a spherical filter media made of polymer materials. The main reason for its replacement is the loss of filter media that occurs during sludge discharge; we observed a small amount of such filter media in the salt sludge tank on site. According to Jintan Jindong, no replacement has been necessary yet after more than two years of operation, and the operating costs associated with this technology are the lowest among various alternatives. This was one of the main reasons why Jintan chose the CN membrane technology in the first place. Ceramic membranes suffer from issues such as membrane clogging and reduced flux; it has been found that because barium sulfate is very fine and sticky, once it enters the membrane pores of 50 nanometers in size, neither acid washing nor alkali washing can remove it, resulting in a decrease in membrane flux. High-pressure backwashing can easily cause damage to the membrane modules, and due to the brittleness of ceramic membranes, they are prone to damage during replacement. VI. In terms of operating costs, both CN membranes and ceramic membranes are patented products of their respective manufacturers, supplied exclusively, which makes it difficult to control the costs of spare parts ； The membrane principle allows for the use of Gore and Kay membrane modules, which are interchangeable, which is beneficial for controlling operating costs. Based on the above points, we communicated with the design institute, which recommended the Kaimo membrane process. Our next step is to conduct in-depth investigations and discussions regarding the Kaimo membrane process, ceramic membrane process, and CN membrane process. I just created an account and hope to get some good advice on the Haichuan platform; I ask all experts for their guidance!