02-Design Abstract1-设计文档集2-Abstract

The Project of Using 72kt/a Sulfur to Produce Carbon Disulfide from ZRCC- Project Design Summary3CONTENT1. Introduction12. Process Planning22.1 Raw material pretreatment22.2 Claus desulfurization section32.3 The exhaust gas hydrogenation reduction section52.4 Carbon disulfide production section63. Energy-saving design83.1 Heat exchanger network optimization83.2 Methane membrane separation technology94. Plant location & Layout125. Economic analysis145.1 Net cash flow145.2 Estimation of static benefit indicators146. Conclusions15151. IntroductionThe project is to design a set of desulfurization equipment for the ZRCC, and also using the produce of desulfurization to product carbon disulfide. The equipment uses the gas besides sulfur element from the ZRCC to meet emissions standards and product the produce. This process includes raw material pretreatment, Claus desulphurization, tail gas hydrogenation reduction and sulfur methane synthesis four sections. The design process contains 202,000 tons of sulfur-containing waste gas, and the recovery of sulfur is 72,000 tons per year, producing 85,000 tons per year of carbon disulfide, and the desulfurization rate is 99.96%, producing a 99.1% purity. The overall process flow chart is as follows.Fig. 1.1 the overall process flow chart2. Process PlanningThis process comprehensive utilization to the total sulfur-containing waste gas from the ZRCC, the pretreatment of raw materials gathers the gas, then with the oxygen enriched air according to the proportion into the Claus system of desulfurization, exhaust into the hydrogenation process after reaction, the sulfur component will be converted to hydrogen sulfide, the next using the PC enrich the hydrogen sulfide in posterior circulation. The produce sulfur from the Claus section is vaporized and blended with natural gas into a reactor to produce carbon disulfide. The project will be deep desulfurization the gas from the ZRCC to emission standards, then uses the product to produce the carbon disulfide. Designed to deal with sulfur-containing waste gas 202 thousand tons per year, sulfur recovery 72 thousand tons per year, production of carbon disulfide 85 thousand tons per year.2.1 Raw material pretreatmentFig. 2.1 the process flow chart of raw material pretreatmentIn this section, the sulfur-containing waste gas is pressurized by a multi-stage (secondary) compressor after passing through a heat exchanger so that the feedstock reaches a feed rate of 40 C and 2.5 MPa into the absorption tower (T0101) which use the propylene carbonate to absorb the H2S, to ensure that H2S fully absorbed in the case, as much as possible to remove CO2, for the Claus section to facilitate. Tower exhausts to meet the requirements, after the flare system directly emptied. The bottom is rich in H2S-containing propylene carbonate. Rich liquid goes through a pressure reducing valve and a heat exchanger, to 100 , 0.4 MPa feed conditions, then into the desorption tower (T0102) for fractionating. The enrichment gas of H2S from the top of the tower, after compressed into the hydrogen sulfide storage tank to prepare for the use of Claus section. The bottom of the tower for the analysis of the PC, containing a small amount of water, into the water-containing PC tank.2.2 Claus desulfurization sectionFig. 2.2 The process flow chart of Claus desulfurization section（1）Burner sectionIn this section, the gas from the H2S tank reacts with oxygen-enriched in proportion to the oxygen-enriched burner, and one third of the H2S is oxidized to SO2 by oxygen. Then, into the oxygen-deficient combustion furnace Claus reaction, and the COS hydrolyze, the reaction equation is as follows.2H2S + SO2=S2 + 2H2OCOS + H2O=CO2 + H2SAfter two steps of the burner section, the outlet gas is diverted through a shunt valve, 90% of the high temperature gas enters the waste heat boiler for heat exchange, after the multi-stage (secondary) compressor pressure so that the gas reaches 170 , 0.11 MPa, and then into the sulfur condenser to condense, condensed liquid sulfur into the liquid sulfur storage tank, non-condensable gas and the rest high temperature gas about 10% blend, and the temperature is about 300 after mixing, into the Claus section.Note: The use of oxygen-enriched air combustion, the purpose is to reduce the gas volume, thereby reducing the follow-up equipment volume, reduce equipment costs.（2）The first Claus sectionIn this section, the outlet gas of the burner section is diverted through the shunt, 70% of the gas enters the first Claus section, and after the heat exchanger heats up to 330 C, enters the first Claus reactor and controls the combustion furnace. The oxygen-to-air feed rate of the section is precisely controlled by a feed ratio of H2S to SO2 is 2: 1. The main reactions are the Claus reaction and the hydrolysis reaction of COS, the reaction equation is.2H2S + SO2=S2 + 2H2OCOS + H20=H2S + CO2The outlet gas is pressurized to 0.11 MPa by the compressor, condensed into the sulfur condenser, condensed liquid sulfur into the liquid sulfur storage tank, and non-condensable gas is mixed with 30% of the high temperature gas of the other outlet of the diversion valve. The temperature is About 200 after mixing and then into the second Claus section.（3）The second Claus sectionThe exhaust gas from the first Claus section is heat exchanged to 260 C and then direct into the second Claus reactor. The main reaction is the Claus reaction, the reaction equation is:2H2S + SO2=S2 + 2H2OThe outlet gas is pressurized to 0.11 MPa by a compressor and condensed in the sulfur condenser, then the liquid sulfur into the liquid sulfur storage tank, and non-condensable gas enters the exhaust gas hydrogenation reduction section.2.3 The exhaust gas hydrogenation reduction sectionFig. 2.3 The process flow chart of the exhaust gas hydrogenation reduction section（1）Tail gas hydrogenation sectionIn this section, the exhaust gas from the second Claus section through a pressure reduce valve and heat exchanger, then into the adiabatic flash tank to condense the water, and the non-condensable gas through the heat exchanger to exchange the temperature to 260 , so that can directly into the hydrogenation reactor for hydrogenation, the reaction equation is.SO2 + 3H2=H2S + 2H2OCOS + H2O=H2S + CO2CS2 + 2H2O=2H2S + CO2The outlet gas from the hydrogenation reactor enters the H2S enrichment section .（2）Exhaust gas H2S enrichment sectionThe hydrogenation reactor outlet gas is pressurized by a multi-stage (secondary) compressor after heat exchange by a heat exchanger, followed by an adiabatic flash. After the dehydration of the gas into the H2S absorption tower (T0401) to absorb, after the PC absorbed the exhaust, after the flare system to meet the discharge standards, can be directly emptying. Absorbent solution through the pressure reduce valve, heat exchanger heat transfer to 52 , 0.12 MPa feed conditions, then into the desorption tower (T0402) for fractionating. The top of the H2S gas is pressurized by the compressor and passed into the H2S tank. Bottom with a small amount of water PC solution, into the water-containing PC storage tank.（3）PC dehydration sectionMaterials from the water-containing PC storage tank, through the heat exchanger heat transfer to 50 , into the dehydrated tower (T0403) for dehydration. The bottom of the high-purity PC send into the high-purity PC storage tank for recycling. The gas from top of the tower contains a small amount of PC, emptied by the flare system.2.4 Carbon disulfide production sectionFig. 2.4 The process flow chart of the carbon disulfide production section（1）In this section, the sulfur from the liquid sulfur storage tank, through the heat exchanger to vaporize into the flash tank. The sulfur form in the high temperature is S2 as the same as control the feed temperature at about 700 . Natural gas is pressurized to 1.5 MPa by the compressor, into the heat exchanger heat to 200 .（2）The gaseous sulfur is mixed with natural gas into the CS2 reactor for reaction. To prevent methane from coking, the natural gas is controlled from the center of the reaction tube, and the gaseous sulfur is fed from the edge of the reaction tube and the reaction temperature is controlled at 650 C. Reactor outlet gas through the heat exchanger, then into the sulfur condenser, recycling the liquid sulfur into the sulfur storage tank.（3）Non-condensable gas is pressurized by the compressor pressure, and then through the heat exchanger into the condenser condensation, the material reached 14.4 (bubble point temperature), 2.5 MPa feed conditions. then into the desorption tower (T0301) for fractionating. The bottom products of the high-purity CS2 then into the carbon disulfide product storage tank. The top of the tower for the high concentration is H2S gas, then compressor pressure into the H2S tank, to prepare for the use of Claus section.3. Energy-saving design3.1 Heat exchanger network optimizationFig. 3.1 Optimization of the design before the programThis project involved in many Utilities. In order to make full use of Energy, this project by using the Aspen Energy Analyzer software, according to the pinch and threshold design method, combined with the actual situation of the factory equipment arrangement, in meeting the design goal utility cost minimum and equipment cost minimum, under the condition of the various process flows and heat of the matching between the utility, designed a kind of optimum matching scheme of cold and hot flow stocks. More details will be shown in the Aspen process simulation source files and PID drawings.The heat exchanger network number is 29, according to the minimum principle of heat exchanger units, removed a number of heat exchangers, such as heat exchanger energy is very small, even close to 0 kJ/h, which the heat exchangers are not reasonable so that can be removed.Fig. 3.2 The heat exchanger network after optimizationThe number of heat exchangers required for the optimized heat exchanger network is 16, include 6 heat exchangers, after that the structure is more streamlined, and the energy consumption can be saved by 34.36%.Table 3.1 Utility informationThe cold Utilities /(kJ/h)The hot Utilities /(kJ/h)Total amount/(kJ/h)The amount of utility before optimization136533020.658847841.719538086.2The amount of utility after optimization120382994.87860778.0128243772.8Saving energy/%11.83%86.64%34.36%3.2 Methane membrane separation technologyTable 3-2 Permeation rate of gas molecules in asymmetric composite membranes of Polyimide (30 )Serial numberComponentPermeation rate Ji/GPU1CH43.52CO21123H2S1794H2O40005O219.66N23.6We used the MATLAB software to simulate the membrane separation process, and the details information as follows.3.2.1.The program information：clc;clear all%逆流接触的模型_membrane separatorna(1)= 516.3832; nb(1)= 588890; ni(1)= 271874; S=3900; N=1000000; ds=S/N; P_h=17*101325; P_l=101325; %Qa=1/0.0224*0.76*36*76*10-6/101325;%Qb=1/0.0224*0.76/13*36*76*10-6/101325;%Qa=4.219108624*10-6;Qb=215.7772696*10-6;na1_(1)=1E-11;nb1_(1)=1E-11;for i=1:N;na(i)=na(1)-na1_(i);nb(i)=nb(1)-nb1_(i);na1_(i+1)=na1_(i)+Qa*ds*P_h*na(i)/(na(i)+nb(i)+ni(1)-P_l*na1_(i)/(na1_(i)+nb1_(i)+ni(1); nb1_(i+1)=nb1_(i)+Qb*ds*P_h*nb(i)/(na(i)+nb(i)+ni(1)-P_l*nb1_(i)/(na1_(i)+nb1_(i)+ni(1); endR=na(N)/na(1) %甲烷的分离比R_2=nb(N)/nb(1)%硫化氢的分离比hydrogen_1=na1_(N+1)%被富集的那一侧的甲烷摩尔量hydrogen=na(N)%剩下出口的甲烷摩尔量xishouji_1=nb1_(N+1)%被富集的那一侧的吸收剂摩尔量xishouji=nb(N)%剩下出口的吸收剂摩尔量2.The resultsR =0.8870R_2 =0.0144hydrogen_1 =58.3646hydrogen =458.0187xishouji_1 =5.8043e+05xishouji =8.4569e+03The results of MATLAB show that when the effective area is 3900 m2, the polyimide film can achieve separation effect.4. Plant location & LayoutThis factory will be located in ZRCC. Considering the topography and geological structure of the plant and the nature and characteristics of the product and the technological process of the project, the layout of the general factory is finally determined.Fig.4.1 General layout行政区发展用地生产区辅助生产区2辅助生产区1储罐区装卸区 Fig.4.1 Plant functional area 5. Econom