Snamprogetti Urea Production And Purification
Snamprogetti Urea Production and PurificationBachelor Assignment Chemical EngineeringCHBOST-0913/06/2016Winfried de Haas (S2571102)Marcelle Hecker (S2732513)Marc Van der Linden (S2383926)Ron Meulman (S2190737)Jesus Rodriguez Comas (S2453622)606261
Executive SummaryThe purpose of this project was to model a Snamprogetti urea manufacturing plant with thecapacity to produce 12,500 kg/h of molten urea (99.6 wt% pure), and to investigate thetechnology, equipment, and hazards involved in the process.The further intention of the project was to gain an insight into the operations of the plant anddetermine whether the modelled process could be operated more sustainably by reducing thesteam consumption of the system.The discovery of urea’s industrial importance as a fertilizer dates back decades and thispermitted steady and successful evolution of the production process. The technology toproduce the organic substance commercially from ammonia and carbon dioxide feed stockshas therefore been carefully developed and fine-tuned for almost 100 years by variouslicensors. 1The early process developments were largely concerned with improving operating conditions,to ensure higher conversions and thus lower raw material expenses. The Saipem(Snamprogetti), Stamicarbon, and Toyo Engineering processes employed in industry todaycan achieve around 99% conversion of raw materials through the use of the total recycle andstripping technologies developed. 1However, as the importance of sustainable plant operation has become more evident, researchin chemical manufacturing has become focused on achieving the same results in a moreefficient and sustainable manner. Our project also addressed this matter, by investigating thesteam consumption of the Snamprogetti wastewater treatment facility.By modelling the Snamprogetti process, utilising Aspen Plus modelling software, it wasdetermined that 12,500 kg/h of urea could be produced from 7600 kg/h of ammonia and 9200kg/h of carbon dioxide. The steam consumption of this process was investigated and could bedivided into 10 t/h of medium pressure steam demand and around 6 t/h low pressure steamdemand.By focusing on the steam consumption of the wastewater treatment section of the plant, itwas identified that 6.8 wt% urea was evaporated during the final concentration stage of theprocess and entered the wastewater treatment facility. This wastewater required hydrolysingto ensure that less than 10 ppm urea was left in the process condensate to comply withemission regulations.The idea of reducing steam consumption in the wastewater plant by reducing the ureaconcentration in the water requiring treatment led to the modelling of two possibleimprovements for the original plant design.The improvements both relate to recycling the urea, which was evaporated in the vacuumsection of the plant to ensure the urea does not enter the wastewater treatment section. Thefirst solution was a scrubbing system modelled for the vacuum section. It was based on aconcept developed by Urea Casale (the urea recycle system, URS) and produced wastewatercontaining 23 ppb urea. The second idea was an alternative to the scrubbing system, wherecondensers were used instead of scrubbers. This system produced water with 402 ppm urea.Urea Production and Purification (CHBOST-09)Page 1 of 233
Both systems were found to require less MP steam and more LP steam than the originalmodel. The scrubbing system allowed for the complete removal of the hydrolyser, whereasthe condensing system still required the unit to reduce the urea concentration in the effluentto safe levels. Therefore, the scrubbing system reduced MP steam consumption by 2000 kg/h,and the condensing system reduced MP steam consumption by 1800 kg/h. However, unlikethe condensing system, the scrubbing system also required the introduction of 600 kg/h ofwater to supply the scrubbers with scrubbing medium.Thus, the goal of reducing total steam consumption in the wastewater section was achievedby introducing either of the two urea recycle systems to the model. Despite the model notbeing a precise representation of reality, we therefore recommend the addition of either ofthese improvements to reduce MP steam consumption of the process.To ensure the recommended solutions are financially attractive to potential investors, furtherresearch should be carried out on the cost and efficiency of the two alternatives regarding theequipment required in each case. The availability and price of resources (water, natural gas,steam) must also be taken into account to fully determine whether the calculated steamsavings will translate to significant fuel savings in the utility section, as this will determinethe extent to which the recommended recycling systems will improve the sustainability of themanufacture of urea.Urea Production and Purification (CHBOST-09)Page 2 of 233
Table of ContentsExecutive Summary. 1Abbreviation list . 4Chapter 1. Introduction . 5Chapter 2. Process and Technology . 62.1 Chemistry . 62.2 Process Description. 82.3 Technology . 15Chapter 3. Utilities . 273.1 Utility Requirements . 273.2 Utility Specification . 27Chapter 4. Mass and Energy Balance . 304.1 Aspen PFD . 304.2 Stream Summary . 344.3 Control . 36Chapter 5. Equipment List and Specification . 395.1 Equipment List . 395.2 ISBL and OSBL Specification . 48Chapter 6. Research into Process Improvement . 496.1 Early ideas for improvement . 496.2 Promising ideas for improvement . 506.3 Conclusions and Recommendations . 59Appendix 1. Basis of Design . 61Appendix 2. Aspen Model . 90A2.1 Stream Summary Aspen file . 90A2.2 Aspen Model Description . 102Appendix 3. Hazard Analysis. 115A3.1 Hazop Study . 115A3.2 Two scenarios with widespread effect . 174A3.3 Chemical Exposure Index . 180A3.4 Fire Explosion Index. 188Appendix 4. Substances and Specifications . 192A4.1 MSDS and Vademecum . 192A4.2 Material Specifications . 200Appendix 5. Derivation of Equipment Size . 203Appendix 6. Stream Results for Model Improvements . 220Appendix 7. References . 230Urea Production and Purification (CHBOST-09)Page 3 of 233
Abbreviation listASH analyzer switch highCEI chemical exposure indexCFD computational fluid dynamicsCSTR continuous stirred-tank reactorCW cooling waterEXPV expansion valveFEI fire explosion indexFIflow indicatorFIC flow indicator controllerFPV flow pneumatic valveFFC flow fraction controlFLflow lowHAZOP hazard and operability studyHPhigh pressureIcurrentISBL inside battery limitLAH level alarm highLAL level alarm lowLHlevel highLIC level indicator controllerLLlevel lowLPlow pressureLPV level pneumatic valveLSH level switch highLSL level switch lowMED mediumMOC material of constructionMPmedium pressureMSDS material safety data sheetNFPA national fire protection associationNo.numberNRV non return valveOSBL outside battery limitUrea Production and Purification SVTAHTALTETICTPVTSHTSLTTUpressurepressure alarm highpressure alarm lowprocess flow diagramprocess and instrumentation diagrampressure indicatorpressure indicator controllerparts per billionparts per millionpressure pneumatic valvepressure switch highpressure switch lowpressure safety valvepressure transmittersafety valvetemperature alarm hightemperature alarm lowtemperature elementtemperature indicator controllertemperature pneumatic valvetemperature switch highto safe locationtemperature transmittervoltagePage 4 of 233
Chapter 1. IntroductionUrea is an organic white compound manufactured worldwide, in various shapes and sizes,from ammonia and carbon dioxide. It is most commonly used by the agricultural industry as afertilizer, but is also used as an intermediate product in the production of melamine and hasthus found uses in the manufacture of plastics. 2Due to its importance in farming, the technology to commercially produce urea dates back tothe early 1920s. 1 Over the lifetime of the process the technology has experienced manyoverhauls and had many improvements implemented. Urea was initially produced in a ‘oncethrough’ process, where any unreacted materials were discarded and the overall conversion ofCO2 to urea was around 75%. Today, the stripping technology and recycle processes, furtherdiscussed in the chemistry section of this report, have enabled conversions of up to 99%. 1Due to the complexity of the modern day process, a variety of techniques to produce ureahave been patented. The best-known licensors of the technology are Saipem (Snamprogetti),Stamicarbon, and Toyo-Engineering.To develop an understanding of the urea production process, the Snamprogetti technologylicensed by Saipem was investigated and modelled in Aspen process modelling software. Theaim of reproducing the Snamprogetti process was not only to gain an insight into the process,but also to identify any areas where improvements could be made in future to steer the plantin a more sustainable direction.As was previously mentioned, many improvements have already been made and continue tobe made by the licensors of the technology and engineering companies dedicated torevamping ammonia and urea plants. However, as society becomes more aware of itsenvironmental footprint and the large part the chemical processing industry plays, theresearch for process improvements has become mainly focused on sustainability.By modelling a 12500 kg/h urea producing plant and researching the chemistry, thetechnology, the equipment, and the hazards involved in the process, the areas of possibleimprovement were revealed. As high-utility consumption translates to unsustainableoperation and high operating costs, the greatest steam users were identified as potentialtargets for process improvement.It was decided to further investigate the steam supply to the wastewater section of the plant inorder to limit the effect any possible improvements would have on the more complex ureaproducing and purifying sections of the plant.With the incentive to improve the sustainable operation of the urea production plant andreduce the operating cost of the process, it was the purpose of this project to furtherinvestigate whether the steam demand of the wastewater treatment section could be reducedand provide insights and results formulated in this paper.Urea Production and Purification (CHBOST-09)Page 5 of 233
Chapter 2. Process and Technology2.1 Chemistry2.1.1 HistoryUrea has a long and interesting history. It was first discovered in 1727 by the Dutch scientistHerman Boerhaave, when he was able to isolate the compound from urine. 3, 4 A century later,in 1828, urea was synthesized in a chemical lab for the first time. The reaction, which wasdiscovered by Friedrich Wöhler, was a milestone in chemistry, since it was now possible tomake an organic compound from two inorganics substrates without the participation of livingorganisms. The reaction discovered by Wöhler is as follows:AgNCO NH4 (NH2)2CO AgClFigure 1: Friedrich Woehler reactionResearch on the synthesis of urea has continuously progressed since it was first discovered.In the beginning of the 20th century, urea was commercially synthesized by the hydration ofcyanamide obtained from calcium cyanamide 5:CaCN2 H2O CO2 CaCO3 CNNH2CNNH2 H2O CO(NH2)2Figure 2: first commercial synthesis of ureaAfter the invention of the Haber-Bosch process in 1913, where ammonia is synthesized fromhydrogen and atmospheric nitrogen on an industrial scale, both ammonia and carbon dioxidewere easier to obtain. This made it possible to develop a new synthesis route for urea. Thenew route, invented in 1922, is known as the Bosch-Meiser process. In this process, ammoniaand carbon dioxide are reacted in two reversible steps:Figure 3: Bosch-Meiser processFirst, liquid ammonia reacts with gaseous carbon dioxide, forming ammonium carbamate.This reaction is fast and exothermic. In the second slow and endothermic step, ammoniumcarbamate is decomposed to urea and water. The overall reaction is exothermic, since theUrea Production and Purification (CHBOST-09)Page 6 of 233
energy released in the first equilibrium reaction is much higher than the heat needed for thedecomposition of ammonium carbamate (see Figure 3).Although the total reaction is exothermic, full conversion of the substrates is never achieved.The conditions in the process should thus be chosen to increase the conversion towards ureaas much as possible. However, the conditions that favor the first equilibrium are detrimentalto the second one and the conditions that favor the second equilibrium negatively affect thefirst one.The optimal conditions in the synthesis of urea are therefore a compromise: the reaction iscarried out at high temperatures (around 190 C), which enhances the dehydration ofammonium carbamate, but diminishes the production of ammonium carbamate. This iscompensated for by carrying out the reaction under high pressures, thereby shifting the firstequilibrium towards ammonium carbamate formation. Furthermore, the vessel in which thisreaction is carried out should be of a considerable size, to allow the slow formation of urea toreach equilibrium.2.1.2 Development of commercial urea processesSince the conversion of urea is incomplete, the product of the reaction should be purified andseparated from unreacted ammonia, water and unchanged ammonium carbamate. In the past,the ammonium carbamate was separated by lowering the pressure to atmospheric conditions,so that ammonium carbamate could decompose to ammonia and carbon dioxide. This type ofprocess is called “once-through”. Recycling the ammonia and carbon dioxide to make ureawas not considered economical, since they would need to be compressed again. Thus,ammonia was used to make other products, like ammonium nitrate or ammonium sulfate,while carbon dioxide was thrown away.After some years of research, some processes were invented where it was possible to reusethe substrates in the same process. This was done by depressurizing in stages: first to 18-25bar and then to 2-5 bar. Afterwards, the solution was passed through a carbamatedecomposer, from where the ammonia and carbon dioxide were recombined and passedthrough a carbamate condenser, whereas the remaining ammonium carbamate was recycledto the previous section.This recycle process (known as “total recycle”) has two main disadvantages. Firstly, the flowscheme of such a process is rather complex, and so is the amount of process equipmentneeded. Secondly, since there is a considerable amount of water recycled in the carbamatesolution, the conversion of urea is lowered, thereby lowering the overall efficiency of theplant. For this reason, in the early 1960s, the Dutch company Stamicarbon came up with thestripping concept. This invention not only solved both aforementioned issues, but alsoimproved the heat recovery of the process.The position of both equilibriums involved in the synthesis of urea depends on the partialpressures of the reactants. In the total recycle process, the overall pressure reduction lowersthe partial pressure of both reactants, enhancing the decomposition of ammonium carbamate.The stripping concept works by not lowering the partial pressure of only one of the reactants.This is done by feeding carbon dioxide to the stripper and then rerouting it to the reactor,instead of feeding it directly to the reactor. This way, the ammonia in the stripper is ‘strippedUrea Production and Purification (CHBOST-09)Page 7 of 233
out’, lowering the partial pressure of ammonia and thus enhancing the decomposition ofammonium carbamate.The stripping technology was then modified by competitors, such as Montedison, ToyoEngineering Corporation, Urea Casale and Snamprogetti (now Saipem). For this project, theSnamprogetti technology was further investigated and modelled.In contrast to other stripping processes, the Snamprogetti technology does not use carbondioxide as stripping agent, but instead stripping is carried out with ammonia, or thermally.The stripping agent is also not fed directly to the stripper, as is the case with Stamicarbontechnology, but instead the excess of ammonia present in the synthesis solution is used as‘self-stripping’ medium.2.2 Process Description2.2.1 BFD of the processNH3CO2HP synthesisMP decompositionLP decompositionMoltenUreaVacuumconcentrationMP ammoniarecoveryLPcarbamaterecover
section of the plant to ensure the urea does not enter the wastewater treatment section. The first solution was a scrubbing system modelled for the vacuum section. It was based on a concept developed by Urea Casale (the urea recycle system, URS) and pro
Sep 08, 2015 · UREA, DRY 1. IDENTIFICATION PRODUCT NAME: UREA, DRY PRODUCT FORM: MIXTURE SYNONYMS: UREA GRANULAR; UREA MICROPRILLS, UREA PASTILLE; UREA PRILLS PRODUCT USES: AGRICULTURAL, INDUSTRIAL AND FEED GRADE CHEMICAL 2. HAZARDS IDENTIFICATION Causes skin irritatio
Apr 27, 2011 · Accordingly, beginning in August 2001, Technip was an "issuer" within the meaning of the FCPA, Title 15, United States Code, Section 78dd-l. 7. Snamprogetti Netherlands B.V. ("Snamprogetti") was a Dutch corporation headquartered in Amsterdam, The Netherlands, and a wholly owned subsidiary of Snamprogetti S.p.A., an Italian EPC company
activated carbon for urea may be caused by using the activated carbon of different sources. 0 50 100 150 200 0 102040 Activated carbon(g) Concentration of urea(mg/L) 0 5 10 15 20 25 Removal of urea(%) urea removal Fig. 1: Adsorption effect on urea with activated carbon. In order to explain the adsorption o
supplying reliable, efficient and economical urea plants since its establishment 40 years ago. TEC has engineered and constructed, as of the end of 2000, 93 urea plants and 10 urea granulation plants based on TEC technologies, giving a quarter of the world’s total production capacity by t
September 2021 Sales Promotion and Marketing Strategy of Nano Urea (liquid) 883 63 urea consumption of 35.04 million MT, production was 24.6 million MT while import was 9.83 million MT. Imported quantity of urea during 2020-21 was almost four times than the quantity imported during 2005-06. This shows increasing import dependency to meet
Jun 21, 2018 · Hydroxyethyl Urea is a derivative of urea, singly substituted with 2-ethanol. Figure 1. Hydroxyethyl Urea Physical and Chemical Properties This ingredient is a low molecular weight, highly water soluble, hygroscopic solid.3 Light microscopic examination revealed that the particles of Hydroxyethyl Ur
Release Curves for Various Methylene Urea Chains Slow Release Nitrogen – Delay N availability – N available through chemical/biological breakdown – Release rate determined by: Chemical structure Molecular weight Environmental conditions urea mono-methylene urea
2021 ULI AsiaPac Awards for Excellence P r o j e c t C a t e g o r y / S e c t o r Indicate the main pr oject categor y for your project. You can fur ther describe it in the following sections. Select P r o j e c t T y p e Describe your project type, e.g. new de velopment, refurbishment, redevelopment, repurposing, cultural/industrial heritage
