| The excessive moisture content in chloride methanes(CMS) will cause hydrolyzation, over acidification and generation of HC1 in CMS products, as a result to increase the corrosion of equipment in manufacturing and consuming process. The moisture content in CMS products manufactured from natural gas thermal chlorination tends to surpass the limitation standard quite easy, since this process needs to clean the rectifying tower with boiling water and steam aperiodically to remove the high boiling point compounds which accumulate gradually in the tower. The moisture content remained after tower boiling will be brought into the system, resulting in excess of moisture content and acid value limitation of product. It seriously influences the quality of product. Therefore it is a urgent task to decreasethe water content in CMS to a limitation less than 50 ppm in the NG thermal chlorination process.Study was made in this thesis based on the current production condition of thermal chlorination process in Honghe Chemical INC. The suggested measures are as follows:1. Reducing byproducts of high boiling point compound by improving the rawmaterial natural gas purification;2. Controlling the quality of crude chlorination liquid rigidly.It was demonstrated by the manufacturing data, that the content of C2+ components in the raw material natural gas, such as ethane, affects the by-reaction of chlorination greatly. If the value of Ci is below 100 ppm, the amount of high boiling point compounds produced is decreased to a very low value. On the other hand, the excessive moisture content can be removed by rectifying the crude chlorination liquid as CMS and water can form azeotropic mixture which has a different boilingpoint with CMS.The test experiment indicates that better result can be expected when applying hh-4 molecular sieve absorbent to using PSA to remove ethane and other Ci components from the raw material natural gas in thermal- chlorination method for producing chlorinated methane. To match this, the suitable adsorption pressure is 0.4-0.45MPa, desorption vacuum is 0.08-0.09MPa and circulating time is 20-21 minuets. In the reformed technological equipment of 8-tower vacuum desorption flow, the author has reviewed some key technological conditions. For example, the change of impurity content of purified gas along with the absorption pressure as well as the circulating cycle can influence the rate and purity of gas product. The result indicates that: (1) Gas products of different purity can be produced through adjusting absorption cycle. But, the lower the C2+ content, the lower the rate of product Considering both meeting the requirement of product purity and bringing equipment ability into full play, it is better to control the rate of product as 50-52% and make the C2+ content less than lOOppm. (2) Along with the extension of absorption cycle, the rate of product will rise to some extent while the C2+ content will rapidly climb. So, it is better to control the absorption cycle as 20-21 minutes. After transformation, the purification equipment runs smoothly, operates reliably, and the time of washing tower caused by blocking tower is obviously reduced.In this thesis, the author has determined the design plan of applying azeotropic distillation to semifinished chlorinated solution in order to further reduce the moisture content of chlorinated methane. And the author has finished the technological design of azeotrope tower and some main subsidiary equipment, such as reboiler, condenser and so on. The design result indicates that according to the productivity of this equipment, in order to reduce the moisture content of semifinished chlorinated solution from 120ppm to 50ppm, the actual required tray number of float valve tower is 23, and the corresponding height and diameter of tower are respectively 12m and 0.8m. This design work has provided necessary condition for the further innovative work.
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