Removes catalyst ultra-fine powder and emulsified oil from chilled and washed water
Ceramic membrane is used in the field of coal chemical oil-water separation. It can separate emulsified oil and ultra-fine catalyst particles in water. The removal rate of emulsified oil is over 90%, and the removal rate of catalyst is up to 99%. It can effectively solve the problems of water washing towers and heat exchangers. Blocking problem, guarantee the stable operation of the device; save investment and land occupation, short process, simple operation, suitable for technical transformation of coal chemical projects.
I. Craft background
Methanol-to-olefins (MTO) units are the key units of coal-to-olefins projects. In the actual production process, MTO product gas still contains a small amount of catalyst fines and oily substances after passing through a three-stage cyclone, and is used in subsequent water systems. Condensation, accumulation, and emulsification form sludge and emulsion, which accelerates the blockage of equipment such as trays, heat exchangers, and air coolers in the water system. At the same time, it also makes it difficult to separate the reused water and increases the energy consumption of the device.
Aiming at the emulsified oils and catalysts in the quench water and wash water of the MTO process, Jiangsu Jiuwu High-tech Co., Ltd. developed a ceramic membrane separation technology to purify the quench water and wash water to solve the problem of emulsification oil and catalyst blocking the equipment in the water system.
Second, process characteristics
(1) High separation accuracy and thorough removal of impurities. The separation precision of ceramic membrane is as high as 50nm, which can completely remove catalyst ultra-fine powder and emulsified oil in quenching water and washing water, and the separation efficiency is above 99%.
(2) No need to add chemicals. The quench water and washing water can be directly processed into the ceramic membrane separator without the need to add flocculants or demulsifiers, which saves the cost of medicine.
(3) The process is simple. The ceramic membrane separation system does not require complicated pretreatment, simple process, high system integration and easy operation.
Third, the process overview
This process uses ceramic ultrafiltration membrane cross-flow filtration technology to remove catalysts and emulsified oil impurities from quench water and wash water. The quench water and washing water are driven by the pump into the ceramic membrane filter, the catalyst ultrafine powder and emulsified oil are trapped in the concentrated liquid by the ceramic membrane, and the purified water is filtered through the ceramic membrane to penetrate into the system and continue to be used. The ceramic membrane has high filtration accuracy and good water quality. It completely solves the impact of impurities in the quench water and washing water on the MTO water system equipment, avoids the blockage of the trays, heat exchangers and air coolers, greatly extends the equipment operation time, and improves system stability. And reduce energy consumption.
Fourth, technical advantages
(1) Advantages of water production . Due to the small particle size of the catalyst particles, 80% of which is below 10 μm, the conventional hydrocyclone separator has a poor separation effect. Even the separation efficiency of the high-efficiency micro-swirl separator does not exceed 90%, and the water-producing catalyst content is about 30mg / L. The ceramic membrane separation accuracy is as high as 50nm, the separation efficiency of the catalyst granule emulsified oil particles is more than 99%, and the content of water-producing catalyst and emulsified oil is less than 5mg / L.
(2) Cost advantage . Take the MTO device of a coal chemical company in Baotou as an example. After the device entered the commercial operation phase in 2011, due to the blockage of the heat exchanger during the production operation, it needs to be cleaned 3 times a week, each cleaning cost about 20,000 yuan, The annual cleaning cost is about 3 million yuan; the main water washing tower tray is blocked, and the tower is partially shut down for cleaning. During the product gas release torch, the methanol consumption is more than 3 million yuan; xylene injection is used to solve the tray jam problem and the annual xylene consumption is The cost is over 1 million yuan. In addition, energy consumption is greatly increased due to system blockage. If ceramic membrane separation technology is used to solve the problems of catalyst and emulsified oil in quench water and washing water, the annual operating cost can be saved over 7 million yuan.
(3) Energy saving and environmental protection advantages . In order to solve the problem of MTO water system clogging, some companies consider switching to compressor turbine condensate instead of purified water, but this will lead to waste of purified water resources and increase sewage discharge. If ceramic membrane separation technology is used, there is no need to change the design of the water system, directly improve the quality of purified water, reduce the external discharge of sewage, and because the injection of xylene in the system is avoided, the COD discharge of sewage can be reduced.