| Polyteramemethylene Ether Glycol,also known as tetrahydrofuran polyether,pTMEG for short.It is a homopolymer made by monomer tetrahydrofuran(THF)via cationic open-loop polymerization.Polytetrahydrofuran is one of the main raw materials for making polyurethane and polyurethane elastomers.The production processes of polytetrahydrofuran mainly include homogeneous catalyst process,heterogeneous catalyst process,heteropoly acid catalyst process and CONSER process of Italian.The production process of PTMEG is heterogeneous catalyst.The process is divided into four processes:polymerization process,filtration process,narrow chemical process and alcohol hydrolysis process.The technology of filtration and narrowing process was studied in this paper,mainly focusing on the following three aspects:the actual capacity of the plate and frame filter press in the filtration process,the optimal low molecular removal rate of narrow chemical sequence and economic benefits.The main work is as follows:1.Filtration process.(l)Change the cooling method of filter cake through process optimization,ehange the original nitrogen and circulating water cooling method to the continuous nitrogen cooling method,and reduce the content of PTMEG in waste filter cake.After optimization,the content of PTMEG in filter cake decreased from 57.90%to 51.10%.(2)Reduce the feed proportion of methanol sodium and magnesium sulfate,and increase the cumulative treatment amount of plate and frame filter press.Through the tracking of the carbonyl ratio and alkali value of the PTMEG index,it is concluded that 210 ppm is the optimal feed ratio of methanol sodium,and 720 ppm is the optimal feed ratio of magnesium sulfate.Under the optimal feed ratio of methanol sodium and magnesium sulfate,the single cumulative treatment amount of single plate frame increases by 15 tons on average.(3)As a filter aid,rice husk ash is used to adjust the amount of pre-coating for the plate and frame filter press.By comparing the cumulative treatment amount of the plate and frame filter press with different amount of pre-coating,the optimal amount of pre-coating is 180 kg.In the case that the precoated capacity of the fixed plate frame is 180 kg,the cumulative capacity of the plate frame filter press under the situation of continuous feeding flow of rice husk ash is compared,and it is concluded that the optimal continuous adding flow is 9 kg/h,and the single cumulative capacity of the single plate frame increases by 32 tons.2.Narrow chemical sequence.Investigated the influence of two factors on the removal rate of low molecular,the first factor for short film evaporator temperature,the fixed narrow chemical feed rate,raise the temperature of short film evaporator,track and analyze PTMEG products molecular weight,viscosity and molecular weight ratio index,it is concluded that when short film evaporator temperature is 220? for the optimal conditions,the molecular weight and viscosity can satisfy the requirements of customers;The second factor is the speed of short-range film evaporator,which increases the speed of short-range film evaporator.lt is concluded that 90 Hz is the optimal speed of the agitator,and the molecular weight and viscosity meet the customer's requirements,and the optimal low molecular removal rate is 2.51%.3.Economic and environmental benefits.Through the process optimization of filtration and narrow chemical sequence,the annual economic benefit is estimated to be 2,915,100 yuan.The filter cake of the plate and frame filter press is general solid waste,and the yield of filter cake is reduced by 93.64 tons in the whole year through process optimization.For other production enterprises in the same industry,it has certain reference significance in protecting the environment,saving energy and reducing pollution. |
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