39
Design S2 Title: Production of 1,4-butanediol Authors: Nick Pinkerton, Karen Schmidt, and James Xamplas Date Presented: March 14, 2014 Introduction 1,4-butanediol (BDO) is traditionally made from petroleum- derived feedstocks in a variety of processes such as the Reppe (acetylene-based), Mitsubishi (butadiene-based), and Davy (maleic acid-based) processes (Nexant.com). Recently, because of the continually high price of crude oil and the desire to be environmentally-conscious, there has been a push toward the use of feedstocks derived from biomass. Bio- succinic acid can be easily used in the Davy process as a substitute for maleic acid to form the end product, BDO (Nexant.com). It is this process that Team S2Kool4Skool has chosen to develop for a new bio-butanediol plant, because the Davy method is mature and requires no new innovations, and because an appropriate feedstock of bio-succinic acid is now available. The plant will be located in East Carroll Parish, Louisiana. This county is also home to Myriant; located in Lake Providence, they are the largest domestic provider of bio-succinic acid (Icis.com). Furthermore, Lake Providence is conveniently located on the Mississippi River, which will allow for affordable transportation of our bio-based butanediol product. The intent of this project is to produce 45,000 metric tonnes of 99.5 wt% 1,4-butanediol per year in a new plant in Lake Providence, LA. The plant will run 24 hours per day for 350 days out of the year, allowing approximately two weeks for a maintenance shutdown. As there are several techniques for producing 1,4 butanediol in industry, the first step was to determine a synthesis path. Based on the chosen path, reaction kinetics, and required production rate of the process, a reactor system was then designed. Next, the process was designed to deliver the

butanodiol

Embed Size (px)

DESCRIPTION

El butanodiol se conoce como un producto de fermentación bacteriana desde los inicios del siglo pasado. De hecho durante la Segunda Guerra Mundial la producción de 2,3- butanodiol mediante fermentación fue de un gran interés, principalmente porque servía como precursor para la fabricación de 1,3-butadieno. Sin embargo, ninguno de los procesos desarrollados fue aplicado a escala comercial y poco a poco fueron abandonados con la introducción de las tecnologías petroquímicas.

Citation preview

Design S2Title: Production of 1,4-butanediolAuthors: Nick Pinkerton, Karen Schmidt, and James XamplasDate Presented: March 14, 2014Introduction1,4-butanediol (BDO) is traditionally made from petroleum-derived feedstocks in a variety of processes such as the Reppe (acetylene-based), Mitsubishi (butadiene-based), and Davy (maleic acid-based) processes (Nexant.com). Recently, because of the continually high price of crude oil and the desire to be environmentally-conscious, there has been a push toward the use of feedstocks derived from biomass. Bio-succinic acid can be easily used in the Davy process as a substitute for maleic acid to form the end product, BDO (Nexant.com). It is this process that Team S2Kool4Skool has chosen to develop for a new bio-butanediol plant, because the Davy method is mature and requires no new innovations, and because an appropriate feedstock of bio-succinic acid is now available. The plant will be located in East Carroll Parish, Louisiana. This county is also home to Myriant; located in Lake Providence, they are the largest domestic provider of bio-succinic acid (Icis.com). Furthermore, Lake Providence is conveniently located on the Mississippi River, which will allow for affordable transportation of our bio-based butanediol product. The intent of this project is to produce 45,000 metric tonnes of 99.5 wt% 1,4-butanediol per year in a new plant in Lake Providence, LA. The plant will run 24 hours per day for 350 days out of the year, allowing approximately two weeks for a maintenance shutdown.As there are several techniques for producing 1,4 butanediol in industry, the first step was to determine a synthesis path. Based on the chosen path, reaction kinetics, and required production rate of the process, a reactor system was then designed. Next, the process was designed to deliver the reactants to the reactor at the proper operating conditions, and the separations, purification, and waste management steps were designed. Cost estimates were made using costing software and hand calculations. Finally, the process was iterated and optimized to reduce costs.BackgroundGeneral informationBDO is an organic chemical with the molecular formula. It is also a diol with its two hydroxyl groups located at the terminal carbons. BDO has a boiling point of 235 degrees C and is therefore a colorless liquid at standard temperatures and pressures (Nicnas.gov.au).There are many precursors that petrochemical synthesis of BDO uses. The commonality between all of the precursor acids is that they are hydrogenatable. In replacement of one of these petrochemical precursors, our team has been tasked with the challenge of deriving BDO from the bio-based precursor succinic acid. This catalyzed reaction will take place in the presence of hydrogen as the hydrogenating component shown below:

As described in the above reaction, there will need to be at least 4:1 stoichiometric ratio of hydrogen gas to succinic acid. Two moles of water will also be produced along with each mole of BDO. This reaction is exothermic, which requires the reactor to be continuously cooled to maintain our reactor temperature. There are also side products that are produced which include tetrahydrofuran (THF) and -butyrolactone (GBL); however, thanks to catalyst selectivity these byproducts are produced in small quantities.Market analysisButanediol has a quickly expanding market due to new technological evolutions and its growing use as a chemical intermediary in advanced materials. With biological routes being optimized, the potential of biomass-derived chemicals is tremendous. The global demand of BDO was estimated at 1.5 million metric tons in 2011 and is projected to grow at an annual rate of 4.5% for the next several years (Nexant.com). Unlike other chemical products, BDOs profitability and attractiveness to producers lies in its downstream potential. Figure 1 below demonstrates several potential downstream products that can be directly or indirectly synthesized from BDO. The largest of these contributors include THF and GBL.

Figure 1. BDO downstream potential flow chartThe current market demand of BDO is being supplemented by several global chemical companies. These companies include BASF, BioAmber, Purac, Myriant, DSM, Mitsubishi Chemical, Roquette, and OPXBIO. The market shares of these companies were not available for this product; however, with the consistent growth of the BDO market our team feels that the market is not saturated or impenetrable. The current market price of BDO fluctuates between $3.06 and $3.31 per kg for US-made products (Orbichem.com). These prices correlate to a nearly 7 billion dollar industry.Process alternatives1,4-butanediol is traditionally made from petroleum-derived feedstocks in a variety of processes (Ingram and Le, 2013). Recently, because of the continually high price of crude oil and the desire to be environmentally-conscious, there has been a push toward the use of feedstocks derived from biomass. Several companies are currently implementing bio-routes of producing butanediol. Genomatica is using a bioengineered microorganism to convert sugar feedstocks directly to BDO via fermentation (Burk et al., 2011), but most companies are instead using microorganisms to convert sugar to succinic acid. The bio-succinic acid can be easily used in the Davy process as a substitute for maleic acid to form the end product, which is the path that most are choosing, although research is being conducted on alternative pathways (Chung et al., 2013).Process overviewThe newly proposed plant can be divided into four stages: pre-reactor, reactor, post-reactor and distillation. Each section is an integral part to the overall process and demands close attention. See the complete process flow diagram in Figure 2.

Figure 2. Process flow diagramPre-reactorThis chemical process begins with two feedstocks: hydrogen gas and bio-succinic acid. The hydrogen gas will be obtained from a pipeline at 150 atm and will be used in molar excess inside the reactor. The bio-succinic acid will be purchased by Myriant Corporation which is located near the planned plant site. The pricing for this feedstock is approximately $2.12 per kg. The plant will require 63,000 metric tonnes of bio-succinic acid per year to meet the proposed plant capacity. First the bio-succinic acid feed is pumped up to 150 atm to match the hydrogen gas feed, and then it is mixed with the hydrogen gas prior to being sent into heat exchanger E-101 for heating. The heat exchanger brings the two feeds up to 110oC and sends them to the jacketed packed bed reactor.ReactorThe hydrogenation reaction occurs inside of the reactor thanks to the packed catalyst bed. The catalyst used is 0.4% Fe, 1.9% Na, 2.66% Ag, 2.66% Pd, 10.0% Re on 1.5mm carbon support. With this catalyst, BDO is produced with over 90% selectivity and minimal side reactions of THF and GBL (Bhattacharyya and Manila, 2011). The reaction has an operating pressure of 2000-4000 psi and internal reactor temperature of 165C. This temperature allows for about 99.7% conversion of succinic acid (Bhattacharyya and Manila, 2011). Due to the exothermic nature of the reaction, a cooling jacket is required which utilizes downstream cold streams to cool the internal bed to maintain the desired reaction temperature.Post-reactorThe effluent of the reactor is sent back to E-101 as the hot stream. After exiting E-101, the reactor product stream is sent to a secondary exchanger, E-102, where utility cooling water is used to reduce the temperature to an acceptable temperature prior to sending it to a pressure let-down valve. At this point the pressure of the stream is taken from 150 atm to 1 atm. This large pressure drop allows for the stream to split into its vapor and liquid portions in a gas-liquid separator. The vapor stream of the gas liquid separator is primarily hydrogen gas and sent to a flare for disposal. The liquid effluent is at approximately 45oC leaving the separator and is therefore pumped to the reactor jacket for the reaction cooling mentioned previously. After running through the reactor jacket, the stream enters the separation processes.DistillationThe first distillation column, T-101, is a 10 stage column whose primary purpose is separating the THF from the product feed. Due to THFs lower boiling point, the byproduct comes off of the top of the column with mostly water. This distillate is sent to the plant's THF waste storage tank that has the capacity of two weeks. The bottoms of the column is sent to the subsequent distillation column that separates the BDO from the GBL and water. The relatively close boiling points of BDO and GBL, 235oC and 204oC, respectively, create a difficult separation that requires a 15 stage column. The distillate of the column is approximately 23% GBL with balance water. This stream is sent to a storage tank with similar sizing parameters as the THF storage tank. The bottom stream is the final 99.5wt% BDO product. This stream is sent to the final product tank, S-104. Depending on our customer demands and the plant location we have the ability to barge, rail or pipe our product to its final destination. Due to low purity of the byproducts, future iterations are needed to optimize either purifying byproducts or selling impure byproducts. There is definitely an available market for these byproducts that should be researched more extensively to increase profit.Mass and energy balancesUsing an Aspen HYSYS simulation we were able to record the material and energy streams going in and out of the process system. As expected, the material and energy totals for the inlet and outlet streams add together to equal 0. This proves that our system is mathematically prudent and thermodynamically feasible. The total mass flow of the system is 15,639 kg/h and the total energy in and out of the system is 1.41e8 kJ/h.HYSYS simulationThe HYSYS simulation was performed using the NRTL ideal fluid package. After using AspenPlus to verify that the HYSYS package had the appropriate vapor-liquid equilibrium information between THF and water, and between GBL and water, we concluded it was feasible to proceed with that fluid package. The simulation consists of a reactor, a gas-liquid separator, 2 pumps, 3 heaters, a valve, and 2 distillation columns (see Figure 3). The simulation successfully converted the succinic acid feed into the desired products. Also, the combination of the two distillation columns was able to effectively separate the BDO to obtain a 99.5% pure product with 99.5% recovery. In addition, a set was made between the energy required to heat stream 12 and the energy required to cool the reactor so that these values were made equal. Lastly, the condenser and reboiler duties were used in four heat exchangers in order to determine the appropriate size of this equipment as well as the necessary utility flow rates.

Figure 3. HYSYS simulationHealth and safetyChemical propertiesInherent to this process are a number of toxic chemicals. Table 1 summarizes the important safety data including hazard type, odor, color, and exposure limits.

As shown in the above table, the chemicals that this facility will be dealing with will be relatively mild and non-life threatening. Regardless of their perceived threat, chemicals should always be handled with care especially when they are at high temperatures and pressures.Safety proceduresFire. There are many flammable materials that will be included in this process; therefore, fire safety is imperative for all employees. There are countless possible causes of ignition and care should be taken while handling any flammable material whether in the lab or in the field.In case a fire is present on, the following protocol should be implemented: Small fire: Use DRY chemical powder. Large fire: Use alcohol foam, water spray, or fog. Call for backup if unable to control. Immediately contact supervisor and emergency personnel on site. Evacuate to safe distance in case of fires around any hazardous materials or pressure vessels.Spills. Process chemical spills will eventually occur in a plant of this scale. Small spills are likely to occur in a laboratory setting. Large spills could be a result of loss of containment in the system. We must ensure that all personnel are aware of proper spill mitigation protocol. Small spill: Dilute with water and mop or absorb with inert dry material. Dispose of in proper receptacle. Large spill: Keep away from sources of ignition and heat. Prevent rundown to any drains or sewers. Call for assistance on disposal. Absorb material with DRY earth or other non-combustible materials. If spill is due to a loss of containment in the system, quickly consult the PLC and shut any valves to prevent further loss.Exposure. We must ensure that our employees are aware of the possible toxicity levels of each substance and how to handle exposure. The chemicals that are being used in this process are known chemical irritants to the eyes, skin, and throat. Safety measures must be in place to acknowledge this hazard. Due to the possibility of high pressure releases, we will have 2-minute emergency oxygen masks placed strategically throughout the plant to ensure the safety of any operator in the presence of a large release.If exposed to the process chemicals, find nearest eye wash station or safety shower immediately and flush exposed skin for at least 15 minutes. Remove any contaminated clothing. Seek medical attention immediately.Storage. Store chemicals in segregated and approved areas. Any closed containers for laboratory purposes should be placed in cool, well-ventilated areas.The calculated capital costs from Aspen Economic Analyzer are reported in Table 2 for all process equipment. The size of the reactor was calculated from the liquid hourly space velocity given in the 2011 ISP patent (Bhattacharyya and Manila, 2011) and a void fraction estimate of 0.4. Storage tanks were sized to contain up to two continuous weeks of material. The number of distillation trays in each tower and the flow rates through pumps, vessels, and the flare were calculated in HYSYS. Heat exchange areas were given in Aspen Energy Analyzer or from HYSYS.

In addition to the above equipment, our plant will require an ion exchanger to produce deionized process water from the municipal water. This is estimated to cost $42,000 in capital cost.Cash flow analysisSummarizing the important takeaways from the economic analysis, this process will return a revenue of 144 MM$ annually. Offset by production costs, the yearly cash flow is approximately 2.7 MM$, except for in the years in which the catalyst must be reinstalled (approximately every 5 years). At a cost of 2.5 MM$, the cash flows in those years decrease to approximately 0.2 MM$. This analysis assumes the plant will take 2 years to construct, and will operate at 50% in its first year. Furthermore, an interest rate of 10% was assumed with a tax rate of 38% (the maximum for corporate gains taxes). Using the 7-year MACRS depreciation method, the 20 year NPV for the project is 4.3 MM$. With an IRR of 15.1%, which is greater than the assumed interest rate, this project looks to be profitable. Further optimization techniques should be used in future iterations to further increase profitability. See Tables 3 and 4 for key economic information.

Sensitivity analysisAs seen in Figure 4, the economic evaluation of this process is influenced the most by changes in the sales price and feed cost. A 20% increase in sales price will result in an approximate 120 MM$ increase in NPV whereas a decrease of the same percentage will result in over a 120 MM$ decrease in NPV. Inversely, a 20% increase in feed cost will result in a 115 MM$ decrease in NPV and a 20% decrease in feed cost will result in a 60 MM$ increase in NPV.

Figure 4. Sensitivity analysisTo alleviate the risk associated with feed price, the team researched the price forecasting of bio-succinic acid. We compared the bio-succinic acid price to the adipic acid price over the six years between 2006 and 2012. The price of bio-succinic has remained relatively stable over this time period. Adipic acid, which is a common petrochemical precursor for BDO production, has had large fluctuations in price that result in unstable cash flows and uncertainty from shareholders. Thankfully, the stability of bio-succinic acid is a good sign that this process has a huge potential to be profitable especially if the demand for BDO continues to rise as projected.DiscussionAs described previously, the Davy process was selected as the most promising process of BDO production. The modified Davy process involves the hydrogenation of bio-succinicic acid with a Pa,Ag,Re catalyst and hydrogen gas. This process has many advantages, one being that it has mature technology that has been improved over the last 20 years. Additionally, the conversion to of succinic acid is virtually complete. Finally, overall plant yields can reach as high as 94 mol%.Streams ahead of the pressure valve (PRV-101) are at approximately 1.51e4 kPa, and streams after the pressure valve are between 100 and 450 kPa. Furthermore, operating temperatures do not exceed 200C, including safety factors. These operating conditions contribute to the feasibility of the process, as all the components can be designed with reasonable dimensions (wall thickness, cap type, etc.).Of particular interest are the large costs of the reactor and pump P-101. The reactor costs nearly 2 MM$ because it has a moderate size with a liquid volume of 16.7 m3, and it operates at 150 atm, which requires a strong stainless steel shell for safety purposes. Pump P-101 has such a large capital cost because it is a centrifugal multistage pump that also needs to be made of stainless steel to withstand pressuring the succinic acid feed to 150 atm.Financial indicators for the proposed plant suggest that it will be moderately profitable, and additional optimization should be performed before making the capital investment. There is a fair amount of risk associated with the implementation of this production facility, and the return at this juncture may not justify the risk.The process design and simulation in HYSYS has relied on several key assumptions, which are cause for certain limitations to the results. First, the conversions and selectivity of the catalyst, while taken from literature sources, are assumed to be true. Furthermore, the assumption of negligible side reactions and products was made. It is possible that small waste products in the form of succinates also form in the reactor. Therefore, the main limitation of this model is generally due to reaction specifications.There are certain safety concerns that go along with the proposed process. First, there are many pipes and vessels that will be at a pressure of approximately 150 atm. Extra insulation and protection must be applied to the piping that contains highly pressurized fluids, to prevent operator injury. Furthermore, the PFR is at a slight risk for runaway reactions due to the exothermic nature of the reaction. The temperature of the reactor must always be monitored by an operator, and the jacket cooling system requires a backup system as well. A benefit of this process is that there are no toxic or severely hazardous components in the process. Additionally, there are no instances of temperature greater than 200C.The process design will be fitted with instrumentation and controls to ensure stable operation. These controls, including sensors and valves, minimize potential damage to components due to variation in plant conditions, as well as optimizing the overall performance. For example, the piping entering the tower will be fitted with a control loop. In the direction of flow, a sensing instrument first detects the pressure of the fluid, and then sends a signal to the controller. If the pressure is not within the operating limits, the actuator is signaled to close or open a control valve which is located farther down the stream.ConclusionThe Evanston Chemical Engineering Division suggests a process that produces 45,000 tonnes/year of 99.5 wt% 1,4-butandeiol to enter the market with an appropriate market share. The feasibility of producing BDO as a significant process was investigated. A wide range of BDO production processes were researched, with a modified Davy process being identified as having the most potential. Using a Pa,Ag,Re catalyst on carbon support, this process converts bio-succinic acid to BDO with approximately 94% conversion. This process was designed in Aspen HYSYS, and economic analysis was conducted in Aspen Economic Analyzer. Total capital costs of the project are 12.2 MM$, with a simple payback period of 5.2 years. Total operational costs annually are 139.7 MM$. The process design was successful, with the capability of producing the desired production of BDO.RecommendationsGiven the moderate profitability of this process design, it is recommended that Evanston Chemicals explores further optimization techniques to increase the profitability of this process. This includes investigating sales of the -butyrolactone byproduct, recycling process water, and further optimizing utility streams for the distillation tower.Second, we would like to investigate recycling the 2300 kg/h of water produced in the reaction. Our succinic acid enters the reactor as a 50 wt% solution in water, so we should look into replacing some of this with the product water. Not only will this decrease our water bill, but it will also lower the cost of ion exchange.ReferencesBhattacharyya A, Manila MD, inventor; ISP Investments Inc., assignee. Catalysts for maleic acid hydrogenation to 1,4-butanediol. United States Patent US 7935834 B2. 2011 May 3.Burk MJ, Stephen J, Dien SJV, Burgard AP, Niu W, inventor; Genomatica Inc., assignee. Compositions and methods for the biosynthesis of 1,4-butanediol and its precursors. United States Patent US8067214 B2. 2011 Nov 29.Chung SH, Kim MS, Eom HJ, Lee KY. Hydrogenation of Succinic Acid Using Ruthenium Nanoparticles Embedded Catalysts. Proceedings of 2013 AIChE Annual Meeting; 2013 Nov 6; San Francisco, USA.Icis.com. Chemical industry awaits for bio-succinic acid potential [Internet]. Surrey: Reed Business Information Limited; c2015 [cited 2015 Feb 26]. Available from:http://www.icis.com/resources/news/2012/01/30/9527521/chemical-industry-awaits-for-bio-succinic-acid-potential/.Ingram A, Le B. 1,4-butanediol/tetrahydrofuran (BDO/THF) [Internet]. Wheaton: Nexant Inc.; c2011- [updated 2013 Apr; cited 2015 Feb 28]. Available from:http://thinking.nexant.com/sites/default/files/report/field_attachment_abstract/201304/2012_3_abs.pdf.Nexant.com. Is Bio-Butanediol Here to Stay [Internet]? Wheaton: Nexant Inc.; c200015 [cited 2015 Feb 28]. Available from:http://www.nexant.com/about/news/bio-butanediol-here-stay.Nicnas.gov.au. Butanediol (1,4-butanediol) factsheet [Internet]. Sydney: National Industrial Chemicals Notification and Assessment Scheme [cited 2015 Feb 28]. Available from:http://www.nicnas.gov.au/communications/publications/information-sheets/existing-chemical-info-sheets/other-information-sheets.Orbichem.com. Chemical Market Insight & Foresight-On A Single Page 1,4-Butanediol [Internet]. Tecnon OrbiChem; c2004-15 [cited 2015 Feb 26]. Available from:http://www.orbichem.com/userfiles/CNF%20Samples/bdo_13_11.pdf.

Diseo S2Ttulo: Produccin de 1,4-butanodiolAutores: Nick Pinkerton, Karen Schmidt, y James XamplasFecha Presentado: 14 de marzo 2014Introduccin1,4-butanodiol (BDO) se hace tradicionalmente a partir de materias primas derivadas del petrleo en una variedad de procesos tales como la Reppe (basado acetileno-), Mitsubishi procesos (butadieno-based), y Davy (a base de cido maleico-) (Nexant. com). Recientemente, debido al continuo alto precio del petrleo crudo y el deseo de ser consciente del medio ambiente, ha habido un empuje hacia el uso de materias primas derivadas de la biomasa. Bio-cido succnico se puede utilizar fcilmente en el proceso de Davy como un sustituto de cido maleico para formar el producto final, BDO (Nexant.com). Es este proceso que el equipo S2Kool4Skool ha optado por desarrollar una nueva planta de bio-butanodiol, debido a que el mtodo de Davy es maduro y no requiere de nuevas innovaciones, y debido a una alimentacin adecuada de cido succnico bio ya est disponible. La planta se encuentra en Carroll Parish Oriente, Louisiana. Este condado es tambin el hogar de Myriant; ubicado en Lake Providence, son el mayor proveedor nacional de cido succnico bio (Icis.com). Por otra parte, Lake Providence est situado a orillas del ro Mississippi, lo que permitir el transporte asequible de nuestro producto butanodiol de base biolgica. La intencin de este proyecto es producir 45.000 toneladas mtricas de 99,5% en peso de 1,4-butanodiol por ao en una nueva planta en Lake Providence, LA. La planta funcionar 24 horas al da durante 350 das al ao, lo que permite aproximadamente dos semanas para una parada de mantenimiento.Como hay varias tcnicas para producir 1,4 butanodiol en la industria, el primer paso fue determinar una ruta de sntesis. Basado en el camino elegido, la cintica de reaccin, y la tasa de produccin requerida del proceso, un sistema de reactor fue entonces diseado. A continuacin, el proceso fue diseado para entregar los reactivos al reactor a las condiciones de funcionamiento adecuadas, y las separaciones, la purificacin, y los pasos de gestin de residuos fueron diseados. Las estimaciones de costos se realizaron con un costo de software y manuales clculos. Finalmente, el proceso se itera y optimizado para reducir los costos.Informacin generalBDO es un producto qumico orgnico con la frmula molecular. Tambin es un diol con sus dos grupos hidroxilo situados en los carbonos terminales. BDO tiene un punto de ebullicin de 235 grados C y por lo tanto es un lquido incoloro a temperaturas y presiones estndar (Nicnas.gov.au).Hay muchos precursores que utiliza la sntesis petroqumica de BDO. La coincidencia entre todos los cidos precursores es que son hidrogenable. En sustitucin de uno de estos precursores petroqumicos, nuestro equipo se ha encargado el desafo de derivar BDO a partir del cido succnico precursor de base biolgica. Esta reaccin catalizada se llevar a cabo en presencia de hidrgeno como el componente de hidrogenacin se muestra a continuacin:+ CalorComo se describe en la reaccin anterior, no tendr que ser al menos 4: 1 relacin estequiomtrica de gas de hidrgeno a cido succnico. Dos moles de agua tambin sern producidas con cada mol de BDO. Esta reaccin es exotrmica, lo que requiere el reactor a ser enfriado continuamente para mantener la temperatura de nuestro reactor. Hay tambin productos secundarios que se producen, que incluyen tetrahidrofurano (THF) y -butirolactona (GBL); sin embargo, gracias a la selectividad del catalizador estos subproductos se producen en pequeas cantidades.Anlisis de mercadoButanodiol tiene un mercado en rpida expansin debido a las nuevas evoluciones tecnolgicas y su creciente uso como intermediario qumico en materiales avanzados. Con rutas biolgicas estn optimizando, el potencial de productos qumicos derivados de la biomasa es tremendo. La demanda mundial de BDO se estim en 1,5 millones de toneladas mtricas en 2011 y se prev que crezca a una tasa anual del 4,5% para los prximos aos (Nexant.com). A diferencia de otros productos qumicos, la rentabilidad de BDO y atractivo para los productores radica en su potencial de aguas abajo. Figura 1 a continuacin muestra varios productos derivados potenciales que pueden ser directa o indirectamente sintetizados a partir de BDO. El mayor de estos contribuyentes incluye THF y GBL.

Figura 1. BDO diagrama de flujo aguas abajo potencialLa demanda actual de BDO mercado est siendo complementada por varias compaas qumicas globales. Estas empresas incluyen BASF, Bioamber, Purac, Myriant, DSM, Mitsubishi Chemical, Roquette y OPXBIO. Las cuotas de mercado de estas empresas no estaban disponibles para este producto; Sin embargo, con el crecimiento constante del mercado de BDO nuestro equipo siente que el mercado no est saturado o impenetrable. El precio actual de BDO mercado flucta entre $ 3.06 y $ 3.31 por kg para los productos fabricados en Estados Unidos (Orbichem.com). Estos precios se correlacionan con una industria de casi 7 mil millones de dlares.

Alternativas de proceso1,4-butanodiol se hace tradicionalmente a partir de materias primas derivadas del petrleo en una variedad de procesos (Ingram y Le, 2013). Recientemente, debido al continuo alto precio del petrleo crudo y el deseo de ser consciente del medio ambiente, ha habido un empuje hacia el uso de materias primas derivadas de la biomasa. Varias compaas estn implementando actualmente bio-rutas de produccin de butanodiol. Genomatica est utilizando un microorganismo de bioingeniera para convertir materias primas de azcar directamente a BDO a travs de la fermentacin (Burk et al., 2011), pero la mayora de las empresas estn en lugar de utilizar microorganismos para convertir el azcar a cido succnico. El cido bio-succnico se puede utilizar fcilmente en el proceso de Davy como un sustituto de cido maleico para formar el producto final, que es el camino que la mayora estn eligiendo, aunque la investigacin se lleva a cabo en las vas alternativas (Chung et al., 2013) .Descripcin general del procesoLa planta recin propuesto se puede dividir en cuatro etapas: pre-reactor, reactor, post-reactor y de destilacin. Cada seccin es una parte integral del proceso global y exige mucha atencin. Vea el diagrama de flujo del proceso completo en la figura 2.

Figura diagrama de flujo 2. ProcesoPre-reactorEste proceso qumico comienza con dos materias primas: de gas de hidrgeno y cido bio-succnico. El gas de hidrgeno se obtiene a partir de una tubera a 150 atm y se usa en exceso molar en el interior del reactor. En primer lugar la alimentacin de cido succnico-bio se bombea hasta 150 atm para que coincida con la alimentacin de gas hidrgeno, y luego se mezcla con el gas de hidrgeno antes de ser enviado al intercambiador de calor E-101 para la calefaccin. El intercambiador de calor ocasiona dos alimentaciones hasta 110oC y los enva al reactor de lecho empaquetado con camisa.ReactorLa reaccin de hidrogenacin se produce en el interior del reactor gracias a la lecho de catalizador empaquetado. El catalizador utilizado es de 0,4% de Fe, 1,9% de Na, 2,66% Ag, 2.66% de Pd, 10,0% en Re 1.5mm soporte de carbono. Con este catalizador, BDO se produce con ms del 90% de selectividad y secundarios mnimos reacciones de THF y GBL (Bhattacharyya y Manila, 2011). La reaccin tiene una presin de funcionamiento de 2000-4000 psi y temperatura interna del reactor de 165 C. Esta temperatura permite la conversin sobre el 99,7% de cido succnico (Bhattacharyya y Manila, 2011). Debido a la naturaleza exotrmica de la reaccin, se requiere una camisa de refrigeracin que utiliza corrientes fras aguas abajo para enfriar el lecho interno para mantener la temperatura de reaccin deseada.Post-reactorEl efluente del reactor se enva de nuevo a E-101 como la corriente caliente. Despus de salir E-101, la corriente de producto del reactor se enva a un intercambiador secundario, E-102, en donde se utiliza la utilidad de agua de refrigeracin para reducir la temperatura a una temperatura aceptable antes de enviarlo a una vlvula de bajada de presin. En este punto se toma la presin de la corriente de 150 atm a 1 atm. Esta gran cada de presin permite el flujo a dividirse en porciones vapor y lquido en un separador gas-lquido. La corriente de vapor del separador de gas lquido es principalmente gas hidrgeno y enviado a una antorcha para su eliminacin. El efluente lquido est a aproximadamente 45oC abandona el separador y por lo tanto se bombea a la camisa del reactor para el enfriamiento de reaccin mencionado anteriormente. Despus de ejecutar a travs de la camisa del reactor, la corriente entra en los procesos de separacin.

DestilacinLa primera columna de destilacin, T-101, es una columna de 10 etapas, cuyo propsito principal es separar el THF de la alimentacin del producto. Debido a la baja temperatura de ebullicin del THF, el subproducto se desprende de la parte superior de la columna con todo agua. Este destilado se enva a THF tanque de almacenamiento de residuos de la planta que tiene la capacidad de dos semanas. Los fondos de la columna se enva a la columna de destilacin posterior que separa el BDO desde el GBL y agua. Las relativamente cercanos puntos de ebullicin de BDO y GBL, 235oC y 204oC, respectivamente, crean una separacin difcil que requiere una columna de 15 etapas. El destilado de la columna es de aproximadamente 23% GBL con agua el equilibrio. Esta corriente se enva a un tanque de almacenamiento con parmetros de tamao similares a las del tanque de almacenamiento de THF. La corriente de fondo es la 99.5wt% producto final BDO. Esta corriente se enva al tanque de producto final, S-104. Dependiendo de nuestras demandas de los clientes y de la ubicacin de la planta que tenemos la capacidad de irrumpir, por ferrocarril o pipa nuestro producto a su destino final. Debido a la baja pureza de los subproductos, se necesitan iteraciones futuras para optimizar cualquiera de los subproductos de la purificacin o la venta de subproductos impuros. Definitivamente hay un mercado para estos subproductos que deben ser investigados ms ampliamente para aumentar los beneficios.Balance de energa y masaUsando una simulacin Aspen HYSYS pudimos registrar los flujos de materiales y energa que entran y salen del sistema de proceso. Como era de esperar, los totales de materia y energa para los flujos de entrada y salida se suman a la igualdad 0. Esto prueba que nuestro sistema es matemticamente prudente y termodinmicamente factible. El flujo de masa total del sistema es 15.639 kg / h y la energa total dentro y fuera del sistema es 1.41e8 kJ / h.Simulacin HYSYSLa simulacin HYSYS se realiz utilizando el paquete de fluido ideal NRTL. Despus de usar AspenPlus para verificar que el paquete HYSYS tena la informacin de equilibrio vapor-lquido apropiado entre THF y agua, y entre GBL y agua, llegamos a la conclusin que era factible para proceder con ese paquete de fluido. La simulacin consiste en un reactor, un separador gas-lquido, 2 bombas, calentadores, 3, y una vlvula de 2 columnas de destilacin (vase la Figura 3). La simulacin convirti con xito la alimentacin de cido succnico en los productos deseados. Adems, la combinacin de las dos columnas de destilacin era capaz de separar eficazmente el BDO para obtener un producto puro 99,5% con una recuperacin del 99,5%. Adems, un conjunto se hizo entre la energa necesaria para calentar la corriente 12 y la energa necesaria para enfriar el reactor de manera que estos valores se hacen iguales. Por ltimo, se utilizaron las funciones de condensador y rehervidor en cuatro intercambiadores de calor con el fin de determinar el tamao apropiado de este equipo, as como los caudales necesarios utilidad.

Figura 3. Simulacin HYSYS

Salud y seguridadPropiedades qumicasInherente a este proceso son una serie de productos qumicos txicos. La Tabla 1 resume los datos de seguridad importantes, incluyendo el tipo de peligro, el olor, el color y los lmites de exposicin.

Como se muestra en la tabla anterior, los productos qumicos que esta instalacin estar tratando sern relativamente suaves y no amenaza la vida. Independientemente de su amenaza percibida, productos qumicos siempre deben ser manejados con cuidado, especialmente cuando estn a altas temperaturas y presiones.Los procedimientos de seguridadFuegoHay muchos materiales inflamables que se incluirn en este proceso; por lo tanto, la seguridad contra incendios es imprescindible para todos los empleados. Hay un sinnmero de posibles causas de ignicin y se debe tener cuidado al manipular cualquier material inflamable ya sea en el laboratorio o en el campo.En caso de un incendio est presente en el siguiente protocolo debe aplicarse: Pequeo incendio: Utilizar polvo qumico SECO. Gran incendio: Utilizar espuma de alcohol, agua pulverizada o niebla. Convocatoria de copia de seguridad si no se puede controlar. ponerse en contacto inmediatamente con el personal supervisor y de emergencia en el lugar. Evacuar a distancia de seguridad en caso de incendios alrededor de cualquier material peligroso o recipientes a presin.DerramesDerrames de productos qumicos de proceso finalmente se producirn en una planta de esta escala. Los derrames pequeos pueden producirse en un entorno de laboratorio. Los derrames grandes podran ser el resultado de prdida de contencin en el sistema. Debemos asegurarnos de que todo el personal est consciente de protocolo adecuado de mitigacin del derrame. Derrame pequeo: Diluir con el agua y limpiar, o absorber con material inerte seco. Deseche en un recipiente apropiado. Gran derrame: Mantener alejado de fuentes de ignicin y calor. Prevenir resume a cualquier desage o alcantarillas. Pedir ayuda para la eliminacin. Absorber el material con tierra SECA u otros materiales no combustibles. Si el derrame se debe a una prdida de contencin en el sistema, consulte rpidamente el PLC y cerrar todas las vlvulas para evitar una mayor prdida.ExposicinDebemos asegurarnos de que nuestros empleados son conscientes de los posibles niveles de toxicidad de cada sustancia y cmo manejar la exposicin. Los productos qumicos que se utilizan en este proceso son conocidos irritantes qumicos para los ojos, la piel, y la garganta. Las medidas de seguridad deben estar en su lugar de reconocer este peligro. Debido a la posibilidad de los comunicados de alta presin, tendremos mscaras de oxgeno de emergencia de 2 minutos colocados estratgicamente por toda la planta para garantizar la seguridad de cualquier operador en la presencia de una gran liberacin.Si se expone a los productos qumicos de proceso, encontrar ojo ms cercana estacin de lavado o ducha de seguridad inmediatamente y lave la piel expuesta durante al menos 15 minutos. Quite la ropa contaminada. Busque atencin mdica de inmediato.AlmacenamientoGuarde los productos qumicos en reas segregadas y aprobados. Todos los recipientes cerrados para fines de laboratorio deben ser colocados en lugares frescos y bien ventilados.Ciencias econmicasCosto de equiposLos costos de capital calculadas de Aspen Analizador Econmico se presentan en la Tabla 2 para todos los equipos de proceso. El tamao del reactor se calcula a partir de la velocidad espacial horaria del lquido dado en la patente ISP 2011 (Bhattacharyya y Manila, 2011) y una estimacin de la fraccin de huecos de 0,4. Se dimensionaron Los tanques de almacenamiento para contener hasta dos semanas continuas de material. Se calcularon el nmero de bandejas de destilacin en cada torre y las tasas de flujo a travs de bombas, vasos, y la bengala en HYSYS. Zonas de intercambio de calor se dan en Aspen Energa analizador o desde HYSYS.

Adems de los equipos anteriormente, nuestra planta requerir un intercambiador de iones para producir agua des ionizada proceso del agua municipal. Esto se estima que costar 42.000 dlares en el costo de capital.Anlisis de flujo de efectivoResumiendo los robos de baln importantes desde el anlisis econmico, el proceso volver un ingreso de 144 MM $ al ao. Desplazamiento por los costos de produccin, el flujo de efectivo anual es aproximadamente 2,7 MM $, excepto en los aos en los que el catalizador debe ser reinstalado (aproximadamente cada 5 aos). A un costo de 2,5 MM $, los flujos de efectivo en los aos disminucin de aproximadamente 0,2 MM $. Este anlisis supone la planta tardar 2 aos para construir, y funcionar a 50% en su primer ao. Por otra parte, una tasa de inters del 10% se asumi con un tipo impositivo del 38% (el mximo de ganancias corporativas de impuestos). Utilizando el mtodo de depreciacin MACRS 7 aos, el VAN 20 aos para el proyecto es de 4,3 MM $. Con una TIR del 15,1%, que es mayor que la tasa de inters tcnico, este proyecto parece ser rentable. Tcnicas de optimizacin adicionales deben ser utilizados en futuras iteraciones para aumentar an ms la rentabilidad. Ver Tablas 3 y 4 para la informacin econmica clave.

Anlisis de sensibilidadComo se ve en la figura 4, la evaluacin econmica de este proceso es influenciado ms por los cambios en el precio de venta y el costo de alimentacin. Un aumento del 20% en el precio de venta se traducir en un 120 MM $ incremento aproximado en NPV mientras que una disminucin del mismo porcentaje resultar en ms de un 120 MM $ disminucin de VAN. A la inversa, un aumento del 20% en el costo de alimentacin se traducir en un 115 MM $ disminucin de VAN y una disminucin del 20% en el costo de alimentacin se traducir en un 60 MM $ incremento en VAN.

Figura 4. Anlisis de sensibilidadPara aliviar el riesgo asociado con el precio de alimentacin, el equipo investig el pronstico de precio del cido succnico bio. Se compar el precio cido succnico bio al precio de cido adpico en los seis aos entre 2006 y 2012. El precio de la bio-succnico se ha mantenido relativamente estable durante este perodo de tiempo. cido adpico, que es un precursor comn petroqumico para la produccin de BDO, ha tenido grandes fluctuaciones en los precios que dan lugar a flujos de efectivo inestables y la incertidumbre de los accionistas. Afortunadamente, la estabilidad del cido succnico bio es una buena seal de que este proceso tiene un enorme potencial para ser rentable, especialmente si la demanda de BDO sigue aumentando a medida proyectada.DiscusinComo se ha descrito anteriormente, se seleccion el proceso de Davy como el proceso ms prometedor de la produccin de BDO. El proceso de Davy modificado implica la hidrogenacin de cido-bio succinicic con un Pa, Ag, Re catalizador y gas hidrgeno. Este proceso tiene muchas ventajas, un ser que tiene tecnologa madura que se ha mejorado en los ltimos 20 aos. Adicionalmente, la conversin a la de cido succnico es prcticamente completa. Por ltimo, el rendimiento global de la planta puede llegar tan alto como 94% en moles.Streams por delante de la vlvula de presin (PRV-101) se encuentran en aproximadamente 1.51e4 kPa, y arroyos despus de la vlvula de presin se encuentran entre 100 y 450 kPa. Por otra parte, las temperaturas de funcionamiento no excedan los 200 C, incluyendo factores de seguridad. Estas condiciones de funcionamiento contribuyen a la viabilidad del proceso, ya que todos los componentes pueden ser diseados con dimensiones razonables (espesor de pared, de tipo tapn, etc.).De particular inters son los grandes costos del reactor y la bomba P-101. El reactor cuesta casi 2 MM $, ya que tiene un tamao moderado, con un volumen de lquido de 16,7 m3, y que opera a 150 atm, que requiere una fuerte carcasa de acero inoxidable para fines de seguridad. Bomba P-101 tiene un costo tan grande de capital, ya que es una bomba centrfuga multietapa que tambin tiene que ser de acero inoxidable para resistir presionar a la alimentacin de cido succnico a 150 atm.Indicadores financieros para la planta propuesta sugieren que ser moderadamente rentable, y la optimizacin adicional se debe realizar antes de hacer la inversin de capital. Hay una buena cantidad de riesgo asociado con la aplicacin de esta planta de produccin, y la vuelta en esta coyuntura puede no justificar el riesgo.El diseo de procesos y simulacin en HYSYS se ha basado en varios supuestos clave, que son motivo de ciertas limitaciones a los resultados. En primer lugar, las conversiones y selectividad del catalizador, mientras tomados de fuentes de la literatura, se asumen para ser verdad. Adems, se hizo la suposicin de reacciones secundarias insignificantes y productos. Es posible que los productos de desecho pequeas en forma de succinatos tambin se forman en el reactor. Por lo tanto, la principal limitacin de este modelo se debe generalmente a las especificaciones de reaccin.Hay ciertos problemas de seguridad que van junto con el proceso propuesto. En primer lugar, hay muchas tuberas y recipientes que estarn a una presin de aproximadamente 150 atm. Aislamiento adicional y proteccin deben ser aplicadas a la tubera que contiene fluidos altamente presurizados, para evitar lesiones al operador. Adems, el PFR es en un ligero riesgo de reacciones incontroladas debido a la naturaleza exotrmica de la reaccin. La temperatura del reactor debe ser siempre supervisado por un operador, y la chaqueta sistema de refrigeracin requiere un sistema de copia de seguridad tambin. Un beneficio de este proceso es que no hay componentes txicas o extremadamente peligrosas en el proceso. Adems, no hay instancias de temperatura mayor que 200 C.El diseo del proceso ser equipado con la instrumentacin y controles para garantizar un funcionamiento estable. Estos controles, incluyendo sensores y vlvulas, minimizar el dao potencial a los componentes debido a la variacin en condiciones de la planta, as como optimizar el rendimiento global. Por ejemplo, la tubera de entrar en la torre estar equipada con un bucle de control. En la direccin del flujo, un instrumento de deteccin detecta primero la presin del fluido, y luego enva una seal al controlador. Si la presin no est dentro de los lmites de funcionamiento, el actuador se sealiza para cerrar o abrir una vlvula de control que se encuentra ms abajo en el arroyo.