20102 设计文档集0-Abstract

80 thousand tons / year MMA production project of Maoming petrochemical Project summaryWORTH DOING 15Project summary1. Project introductionMethyl methacrylate was produced from the ethylene cracking unit of the general plant and the isobutene in the carbon four extractor of butadiene extraction unit, which extended the industrial chain of the enterprise.This project is done for the Maoming branch of Sinopec to design a plant with a annual output of 80 thousand tons of methyl methacrylate,using isobutene from C4 raffinate oil as feedstock. It is built in the industrial transfer industrial park of Maoming. In the process design, the team takes into account economic efficiency and cleaner production. The idea is clear and highlights are highlighted in the following aspects:The recycling process of methanol, industrial soft water and other substances can be realized in the process to raise the utilization ratio of atoms and realize clean industrial production.The process flow is optimized by heat pump distillation, medium pressure steam of pagoda, internal heat integrated azeotropic distillation column, pre azeotropic distillation and membrane separation technology.High purity isobutylene was prepared by pretreatment of carbon four oil by MTBE synthetic cracking process, and methyl methacrylate was prepared by two step oxidation and esterification process, and the subsequent three wastes were treated in detail.A slurry bed reactor was used to improve the reaction capacity. The internal heat integrated azeotropic distillation column was used to improve the separation capacity. The pre azeotropic distillation and film separation combined process improved the quality of the product.2. Determination of raw materials and productsThis project is done to be a 80 thousand ton / MMA plant. The raw materials are isobutylene from the carbon four raffinate of Sinopec Maoming ethylene cracking unit and butadiene extractor. Table 1 consists of carbon four extractive oil.Table 1 carbon four extractive oil compositionRaw material compositioncontentpropane0.0002Cyclopropane0.0009Isobutane0.038N-butane0.14acetylene0.0005trans-2-butene0.07531-butene0.26isobutene0.43cis-2-butene0.03491,3- butadiene0.0004propylene0.0065Vinyl acetylene0.00651- butyyne0.0066Other0.0002In total1The product of this project is high purity methyl methacrylate with a content of 99.99%. Table 2 is a product of methyl methacrylate.Table 2 product compositionProduct compositioncontentMethyl methacrylate0.9999water0.00013. process planningThis project programme was determined after product selection and process demonstration, i.e., isobutylene was obtained from C4 raffinate oil by methanol etherification and cracking method, and methacrylic acid was prepared by two step method of isobutylene. The technological process consisting of raw material pretreatment section, MAL synthesis section, MMA synthesis and purification section was designed, and the whole process steady state simulation and optimization were realized. The process is shown in Figure 1. See the chemical process system in the fourth chapter of the preliminary design manual.Figure 1 process flowIn the raw material preprocessing section, the excess methanol from the tank is mixed with the carbon four oil in the mixer after the methanol purifier, then into the MTBE synthesis reactor, and the isobutene in the raw carbon four is mostly converted to MTBE, and a small amount of unreacted isobutene and the supplemental methanol are entered into the MTBE reaction distillation column respectively. After reaction and separation of the rectifying tower, the carbon four was discharged at the top of the tower, and MTBE and residual methanol were entered into the MTBE cracking reactor. The MTBE ether in the MTBE reactor was cracked to produce isobutene and methanol, and the products after the cracking and the supplemental water entered the methanol absorption tower respectively. The mixture of water and methanol into the dehydrating tower at the top of the methanol absorption tower the high purity isobutene into the MAL synthesis section, the mixture of water and methanol is discharged from the bottom of the tower, and the water is discharged from the bottom of the tower to the methanol absorption tower, the top of the tower is discharged from the methanol;. Crude methanol enters methanol recovery tower. The main organic impurities are diisobutene and a small amount of methanol. The azeotropic substances are discharged at the top of the tower.In the MAL section, the high purity isobutene，steam from the pretreatment section of the raw material and the excess air enters the mixer and subsequetly lead to the MAL reactor.; The isobutene and the oxygen in the air in the MAL reactor produces methyl acrolein; The products after the reaction and the circulating water from the MMA synthesis and refining section respectively go to the quench tower, and the reactants are cooled. The reaction products after the cooling are discharged at the top of the tower into the dewatering tower, and the waste water is discharged at the bottom of the tower to the waste water treatment station. The reaction products and the recycled methanol are separated into the dehydrating tower and the reaction products are dehydrated. The reaction products after the dehydration are discharged into the MAL purification tower at the top of the tower. The bottom of the tower is discharged from the tower to the cooling tower, and the reaction product after dehydration enters the MAL purification tower with the circulating methanol from the MMA synthesis and refining section, and the oxygen free air is collected at the top of the tower. The mixture of methyl acrolein and methanol is discharged into the MMA synthesis and refining section.In the MMA synthesis and refining section, the mixture of MMA and methanol from the MAL synthesis and refining section and the methanol are added into the MMA synthesis slurry bed reactor. The air is pressurized into a MMA slurry bed reactor to react with methacrolein and methanol to produce methyl methacrylate. The oxygen poor air is in a slurry bed reactor. The upper part is discharged, the methyl methacrylate reacted with the excess methanol to the internal heat integrated azeotropic distillation column; the mixture of water and methyl methacrylate and methanol into the internal heat integrated azeotropic distillation column, and the methanol is discharged into the top of the tower and divided into three strands, which circulate back to this section respectively, and MAL The dehydrating tower and MAL purification tower in the section of the industrial section, the uncondensable air in the MMA slurry bed is discharged from the top of the tower, and the bottom of the tower produces methyl methacrylate and water mixture to enter the phase separator; in the phase separator, methyl methacrylate and water are separated automatically into the separation, and the water phase is divided into three parts to the section respectively. The internal heat integrated azeotropic distillation column, the pre reaction mixer and the quench tower of the MAL synthesis section are circulated, the ester interconnects to the pre boiling distillation column, the mixture of methyl methacrylate and water enters the azeotropic distillation tower, the azeotrope of methyl methacrylate and water is discharged into the membrane separation unit at the top of the tower, and most of the water components are membrane After separation, waste water treatment was carried out, methyl methacrylate and a small amount of water components were returned to the pre distillation distillation column, and the pre azeotropic distillation tower bottom was produced with high purity methyl methacrylate and sent to storage tank with inhibitor.4.Energy saving design4.1 Optimization of heat transfer networkIn this project, the amount of public utilities is more. In order to make full use of the energy, this project uses the Aspen Energy Analyzer8.4 software, according to the pinch design method, combined with the actual situation, to carry out the flow share matching, designed an optimal cold and heat flow matching scheme. At the same time, the optimized heat exchanger network is returned to process simulation and PID drawings. See the Aspen Plus process simulation source files and PID drawings.The matching scheme of heat exchanger network in all sections of the plant is shown in Figure 2, and the energy saving effect is shown in Figure 3.Figure 2 matching scheme for heat transfer network in whole process Figure 3 energy saving comparison before and after optimization4.2 Application of heat pump distillationThe use of heat pump distillation in the raw material pretreatment section has the advantages of simple equipment, less investment, good separation effect and low running cost. After Aspen Plus simulation, the total energy consumption of heat pump rectification is reduced by 53.9%. See innovative instructions. The heat pump distillation is simulated in Aspen Plus as shown in Figure 4Figure 4 Simulation of heat pump distillation in Aspen Plus4.3 Medium pressure steam for the by-product of a quench towerIn the MAL synthesis section, a large amount of heat can be used in the quench tower, so the cooling tower is designed to be a form of medium pressure steam, and the medium pressure steam of the by-product is used in the MTBE cracking reactor of the raw material pretreatment section. The detailed description of the process is simulated in Aspen Plus, as shown in Figure 5.Figure 5 medium pressure steam for the by-product of a quench tower4.4 Internal heat integrated azeotropic distillation columnThe internal thermal azeotropic distillation column was used in the separation and separation of methyl methacrylate and methanol in the MMA synthesis and purification section. The process not only improves the separation efficiency, but also saves 11.2% of heat energy and saves 50% of cooling capacity. See innovative instructions in detail. The process is simulated in Aspen Plus as shown in Figure 6.Figure 6 simulation of internal thermal azeotropic distillation column in Aspen Plus4.5 Combined process of pre azeotropic distillation and membrane separationIn the MMA synthesis and refining section, in order to achieve high purity of methyl methacrylate, the team innovatively adopted the combined process of pre azeotropic distillation and membrane separation. The technology can not only greatly improve the quality of products, but also lower energy consumption. See innovative instructions. The simulation of the process in Aspen Plus is shown in Figure 7.Figure 7 Simulation of combined process of pre azeotropic distillation and membrane separation in Aspen Plus5.equipment designThe design process of this project is mainly designed for the MMA synthetic reactor and the MTBE synthesis reaction distillation column. The selection of heat exchangers, tanks, pumps, compressors and other equipment is made. See the specification of typical equipment design.5.1 Liquid solid expansive bed reactorIn the process of MTBE synthesis, the liquid solid expansive bed reactor can not only improve the mass transfer effect, guarantee the utilization of the catalyst, but also improve the heat transfer effect, prevent the local superheat damage in the reactor and reduce the selectivity of two polyisobutylene.Figure 8 density distribution map of the axial diameter of the reactor5.2 Bubble column reactorIn the synthesis of methyl methacrylate, slurry bed reactor with bubbling column is selected. The reactor is gas-liquid-solid three-phase operation, in which liquid-solid two-phase can be treated as homogeneous. The reactor has no moving parts and does not need to be sealed for the agitator; the maintenance cost is low; the intraparticle diffusion resistance is small, and the catalyst utilization rate is high; compared with the agitated reactor as long as the plane space is small; compared with the fixed bed reactor, the high effective heat transfer rate can be brought about by the high liquid circulation rate. See equipment selection and typical equipment designANSYS15.0 is used to simulate the distribution of gas and liquid when the gas distributor is optimized.Fig. 9 gas-liquid distribution diagram of gas distributor5.3 Internal thermal azeotropic distillation columnInternal heat integrated azeotropic distillation column was used to separate methyl methacrylate and methanol in the MMA synthesis and refining section. The inner tower is the rectification section, the plate type tower is adopted, the outer tower is the distilling section, and the bulk Bauer ring is chosen. Heat transfer between high temperature distillation section and low temperature distillation section was carried out to save energy. Both towers were hydraulically checked by CUP-Tower and Aspen Plus V9 software, and both of them met the operation requirements.The temperature distribution of the optimized structure of the tower is analyzed by COMSOL Multiphysics 5.3a. The results are shown as follows.Fig. 10 analysis chart of temperature distribution6. Cleaner productionThis project is a clean production process for the production of methyl methacrylate, which is mainly embodied in the use of two step oxidation and esterification to avoid the production of intermediate methacrylic acid, improve the utilization of raw materials, and recycle waste water to reduce the production of waste water.7. Site selection and layout of factoryThis project will be located at the industrial transfer industrial park of Maoming, Guangdong, near the general plant Sinopec Maoming petrochemical branch.As one of the oil refining bases in Guangdongs petroleum and chemical industry, the park is one of the oil refining bases in which the public facilities are perfect. The enterprise cluster makes the internal industrial chain advantage obvious; the four waste oil from the raw material is directly from the general plant, which is convenient and quick; the three wastes treatment and public engineering are supplied by the supporting industry; the park has also obtained the government policies to help preferential and fund management. Gold technology support, pay attention to the healthy and sustainable development of industry.Figure 11 map of site selection8. Analysis of safety environmentIn this project, Risk System software is used to identify the major hazard sources of methyl methacrylate, carbon four oil, methanol and other storage tanks in the factory area. Based on the physical properties of the material, the source phase analysis of the tank area is carried out. Then, the model prediction of the pool fire accident and the boiling liquid expansion steam explosion are carried out according to the results of the source phase analysis. Prediction and steam cloud explosion model forecast and analyze the damage range of the accident; in addition, ALOHA software is used to simulate the steam cloud explosion, BLEVE accident, pool fire accident and poisoning accident, and the noise evaluation of the plant area and its surrounding environment by using EIAN software; and the production of factory area using Aspen Epselon. The raw sewage was analyzed and evaluated, and the environmental impact assessment was carried out by using the EIAW water quality evaluation and prediction software, and the HAZOP analysis software, the road chemical fire and the explosion hazard index were used to evaluate the risk pre evaluation of the major hazard sources and set up the control system of SIS, DCS and ESD. The stability control of the system.9. Analysis of economic effectThe economic and technical analysis of the factory follows the relevant economic indicators and analysis methods. After fully understanding the market price, the Aspen Economic Analyzer is used to carry out the auxiliary calculation, and the investment, profit and cash flow of the whole plant are estimated and explained in detail. The calculation shows that the total investment of the plant is 663 million 310 thousand and 400 yuan, the annual profit is 309 million 560 thousand yuan, and the investment recovery period is 6.3 years. The analysis results show that our plant is economically feasible and has high economic benefits. Please refer to the fourth chapter - fifth chapter of the feasibility study report.Table 3 comprehensive economic and technical indicatorsSerial numberIndex nameCompanynumerical value1Design scalekt/a82Annual operating timeHour / year80003Total investment in engineering projectsTen thousand yuan65870.14Investment in fixed assetsTen thousand yuan36548.55Direct material feeTen thousand yuan / year64593.86General officerpeople887Annual costTen thousand yuan / year125524.58Total output value of the whole plantTen thousand yuan / year171442.89Total annual net profitTen thousand yuan / year31867.