Discussion is welcome on the analysis and comparison of technical solutions for the post-treatment processes in methanol-to-propylene (MTP) production on a million-ton scale
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This post was last edited by jordan569 on 2013-1-6 at 21:41. Since there are currently no production facilities capable of producing propylene from million-ton quantities of methanol, either domestically or internationally, Datang’s MTP facility can be considered to be of such scale. However, it is difficult to find information regarding comparisons of its process technologies; the reaction and regeneration systems in this facility may be kept confidential, but the post-processing techniques for the materials resulting from the reactions should not constitute any confidential technology. Seeking help: Analysis and comparison of technical solutions for the post-treatment process in methanol-to-propylene (MTP) production. The materials resulting from the MTP reaction should include methane, ethylene, ethane, propane, propylene, various butylenes, n-butane and isobutane, pentenes, pentanes, methanol, dimethyl ether, water, and so on. Since the temperature in the MTP reactor is high while the pressure is low, these materials are likely to be in gaseous form. From an energy-saving perspective, what type of separation process would be appropriate for the subsequent processing of this gas? The first step is definitely cooling; the subsequent processes are quite complex – compression? Deep cold? Or compression + cryogenic cooling? For MTP reprocessing on a million-ton scale, direct compression results in excessive energy consumption! It must be compressed at least to the vapor pressure of propylene at 40 degrees. Technicians from large oil refineries, large petrochemical companies, large design institutes, and large engineering firms are welcome to participate in the discussion on this topic. Process engineers from companies such as Luoyang Institute, Wuhuan, Tianchen, and Global are especially welcome to participate in the discussion. This post can serve as a starting point to spark further discussion. . . . This post was last edited by 1681818 on 2008-4-13 21:22. Note: $ # , $ $
The MTP unit is temporarily divided into 6 units: the reaction unit, the regeneration unit, the gas separation unit, the compression unit, the distillation unit, and the by-product treatment unit (mainly the ethylene purification unit). Based on process calculations, turbine compressors are to be used for 4 stages of compression of the hydrocarbons; in addition, there are also propylene compressors and turbines. The exact numbers cannot be disclosed at present
As for the cooling issue, the propylene refrigeration process is used, with both cold and heat being recycled. The refrigeration process primarily relies on throttling for cooling, with propylene being used extensively for cooling throughout the entire MTP process. The scale of its air cooler should also be very large
I’d like to correct this: in the context of the so-called million-ton-scale MTP projects mentioned by the original poster, the term \"million-ton-scale\" refers to quantities measured in terms of methanol. The Datang MTP project is said to produce 460,000 tons of polypropylene, but when converted to methanol, this amount is approximately 1.67 million tons. The capacity of 1.67 million tons of methanol per plant is based on the \"large-scale methanol\" production process mentioned by Lüzhi Company. The gasifier corresponding to such a large methanol plant is quite large as well. The larger the furnace, the greater the possibility of deflagration. Personally, I think a breakthrough in this bottleneck has not yet been achieved at present.
I would be very grateful if that expert could send me some information on the production of propylene from methanol! QQ: 610433708@qq.com :handshake :handshake
As far as I know, they are generally divided into reaction regeneration, quenching and compression, absorption stabilization, propylene separation, and some auxiliary tasks. These auxiliary positions include heat transfer oil, refrigeration stations, etc.
Large-scale methanol production places high demands on the stability and durability of gasification furnaces, and current gasification technologies are not yet capable of meeting such requirements.
This post was last edited by firefox1981 on 2009-6-29 08:52. Subsequent processing involves heat exchange between the materials involved in the process as well as with circulating water; after the temperature is reduced, compression and separation take place. Of course, the substance still exists in a gaseous state after cooling, and propylene refrigeration is widely used in projects like the Datang project. In terms of energy consumption, heat loss is low, which meets energy-saving requirements. After separation, a specific substance can be selected as needed, while the rest can be used as fuel gas or liquefied gas. Lurgi’s technology is excellent: most of the materials are reused after reprocessing, which increases production with minimal by-products
Question: How should the separated ethylene and C5–C8 olefins be handled?
Currently, there are some patents that describe the separation of MTO and MTP, but there are still very few compared to those related to the reaction process. Regarding the separation of MTP products, the separation techniques used for ethylene can be used as a reference to some extent. The temperature of the gas phase coming out of the reactor is quite high, so a quenching unit similar to those used in ethylene production facilities is necessary ； For stepwise distillation, a certain pressure is required for the product, and a compression unit is necessary; if the product contains acidic gases, an acid gas removal unit must be installed ； The subsequent separation process needs to be designed with factors such as low energy consumption and simple operation in mind ； It is important to note that the MTP product contains certain oxides, which are not present in ethylene plants; therefore, an appropriate oxide removal method must be selected to ensure that the propylene and ethylene products meet the required standards!
For C4+ hydrocarbons, especially olefins, a common practice nowadays is to return them to the earlier reaction stage for reprocessing in order to produce ethylene and propylene. There are many ways to carry out reprocessing, which depend on the catalyst used; this can increase the overall yield of ethylene and propylene.