Ammonium nitrate is typically a white solid and is the salt produced from the reaction of ammonia and nitric acid (Figure 1). The ammonia is the product of the reaction between nitrogen and hydrogen, the two main hydrogen production process for ammonia are natural gas and coal which is predominately used in China.

The ammonia feed for the production of ammonium nitrate is liquid anhydrous ammonia, it is stored as a liquid under pressure to prevent it from escaping to the atmosphere as it becomes a toxic gas. This is the main issue with using anhydrous ammonia and so it must be stored in a safe and secure location (Dana A. Shea, 2013). The nitric acid that is used in the production of ammonium nitrate can be feed into the process; similar to ammonia, or it can be made during the process by reacting nitrogen dioxide and water. There are issues with nitric acid due to it being corrosive and a strong oxidising agent, therefore it must be stored securely so it is not exposed to other substances, so it is not able to react and explode.

What Are Some of The Properties Of Ammonium Nitrate?

Ammonium nitrate is soluble in water, it is highly hydroscopic and is not very reactive, and is stable on its own. The chemical symbol of Ammonium nitrate is NH₄NO₃ its molar mass is 80.043 g/mol, it has ionic bonding and contains two ions: a cation, the ammonium ion (NH₄⁺) and an anion, the nitrate ion (NO₃^–) (Figure 2). The boiling point of ammonium nitrate is 210 deg and its melting point is 169.6 deg and it has a density of 1.72 g/cm^{3 (Pubchem, 2018)}. Ammonium nitrate was discovered in 1659 by a German chemist called Johann Rudolf Glauber.

Ammonium nitrate doesn’t regularly occur in nature due to it being soluble in water and is easily washed away by rainwater, it has been found in certain desert regions however it is found as a mixture with other minerals, but this is rare (Encyclopedia, 2018).  Ammonium nitrate is mostly sold as a solid, the two processes to produce solid ammonium nitrate are prilling and granulation. Prills are produced by sending concentrated ammonium nitrate, which is known as melt, down a prilling tower leaving the bottom of the tower as a solid. Granulation involves using a rotary drum to spray small seed particles of ammonium nitrate with melt to produce granules (United States Environmental Protection Agency, 2018). 

The Ammonium Nitrate Market 

The ammonium nitrate global market size was estimated to be $4.67 billion in 2016, and the global production is estimated to achieve 1700 kilotons by 2022 (Global Information, 2018). The reason that the ammonium nitrate market is so large is due to the high demand for fertilisers and explosives around the world. The ammonium nitrate market is dominated by Europe, the USA, and China in terms of production and consumption, with over 70% of consumption and over 80% of production occurring in these regions (Grand View Research, 2017). 

In today’s market ammonium nitrate prill has two primary applications, the main use of ammonium nitrate prill is in fertilisers, which accounted for nearly 60% of the ammonium nitrate market in 2016 (figure 3). The other main use of ammonium nitrate is in explosives. Ammonium nitrate prill is very important for the agricultural industry as it is one of the key components in fertilisers. 

Fertilisers are typically made up of nitrogen, phosphorous, potassium compounds, and other trace elements (madehow, 2018). Fertilisers work by replacing the chemical components that are taken up by the plants from the soil, this leads to an optimum growing environment for the plants. Ammonium nitrate prills are highly soluble in soil and contain a high nitrogen content (about 33.5%). Nitrogen is an important nutrient for plants as it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide. 

Furthermore, nitrogen is a major component of amino acids that make up proteins, and if a plant doesn’t have proteins it will die. Furthermore, nitrogen is a significant component in nucleic acids such as DNA that allows cells to grow and reproduce (Crop Nutrition, 2018). Therefore, it is evident that nitrogen is very important for plants and with Ammonium nitrate prill having such a high nitrogen content and being inexpensive it is very useful for the agricultural industry. 

Ammonium nitrate prill is used in the manufacturing of explosives, this is due to it being an oxidizing agent and its explosive nature when it reacts with other compounds. ANFO is an extremely explosive compound and it is formed from the mixture of 94% prilled ammonium nitrate (AN) and 6% Fuel Oil (FO) (Cook, 1974), it’s a widely used explosive and accounts for 80% of all blasts that occur in the United States (Green, 2006). The reason that ANFO is so widely used in industries such as mining, quarrying, and demolition, is due to ANFO being low-cost and easy to use (Cook, 1974).   

What are Some Issues with Ammonium Nitrate? 

Issues with ammonium nitrate arise from storage and handling.  In the event of a fire, ammonium nitrate can melt and releases toxic fumes and if it reacts with water, it can form ammonium hydroxide solution which can cause irritation and burns. Thus, it is evident that ammonium nitrate has deadly reciprocations if not handled and stored in a safe and secure condition (Health and Safety Executive, 2018). Furthermore, due to ammonium nitrate being an oxidising agent when it comes into contact with other substances it can react with it can cause large explosions. This has led to incidents such as the Oklahoma bombing which used an ammonium nitrate bomb to destroy a building and killed 168 people (CNN, 2018).

Due to the risk of ammonium nitrate being used as a bomb for acts of terror, the sale of ammonium nitrate is closely monitored; for example, in the United States where the department of homeland security has multiple statutory authorities working for it that regulate the production and sale of ammonium nitrate for security purposes (Dana A. Shea, 2013). Due to the monitoring of ammonium nitrate, it is becoming increasingly harder to buy ammonium nitrate-based fertilisers on a small scale, this has affected the ammonium nitrate market as alternatives such as urea can be used in its place. However, using urea as a fertiliser is problematic as it can lose 40% of its nitrogen content if there is no rainfall within 2 days of it being used. 

The Future of Ammonium Nitrate 

In the future the restrictions that governments have on ammonium nitrate-based fertilisers may tighten; innovation will be the key for the future of fertilisers that rely on ammonium nitrate. A new technology that has recently been produced is a fusion of ammonium nitrate and ammonium sulfate, this fusion produces a product that is less explosive and is more efficient as a fertiliser. It is not regulated so it can be bought by anyone (FUSN, 2018). However, the drawback with this fusion is that it is relatively new and hasn’t been on the market long enough to become an established competitor for ammonium nitrate, which has been used in fertilisers for a very long time and will continue to be used around the world for the foreseeable future. 

Even with competition and innovations, the market for ammonium nitrate will continue to grow, this is due to continued high demand for explosives and fertiliser globally and the simplicity of producing ammonium nitrate and using it. The increased demand for explosives is due to increased military activity around the world and the increased mining in countries such as the USA, India, and Argentina for valuable metals and minerals. This has resulted in more mines opening which require blasting products, thus increasing the demand for ammonium nitrate. The high demand for fertilisers by the agricultural industry is due to the increasing global population, especially in China which uses the largest amount of nitrogen-based fertiliser in the world due to its high population which is increasing (figure 4).

References

CNN. (2018, March 25). Oklahoma City Bombing Fast Facts. Retrieved from CNN: https://edition.cnn.com/2013/09/18/us/oklahoma-city-bombing-fast-facts/index.html

Cook, M. A. (1974). The Science of Industrial Explosives. Salt Lake City: ireco chemicals.

Crop Nutrition. (2018). Nitrogen in Plants. Retrieved from Crop Nutritionhttps: https://www.cropnutrition.com/efu-nitrogen

Dana A. Shea, L.-J. S. (2013). Regulation of Fertilizers: Ammonium Nitrate and Anhydrous Ammonia.Washington: Congressional Research Service.

Encyclopedia. (2018, November 4). Ammonium Nitrate. Retrieved from Encyclopedia.com: https://www.encyclopedia.com/science/academic-and-educational-journals/ammonium-nitrate

FUSN. (2018). Product Data shee 26-0-0-14s. Retrieved from FUSN: http://simplotfusn.com/documents/FUSN-PDS.pdf

Global Information. (2018). Global Ammonium Nitrate Market 2018-2022. Retrieved from Global Information: https://www.giiresearch.com/report/infi666003-global-ammonium-nitrate-market.html

Grand View Research. (2017). Ammonium Nitrate Market Analysis By Application (Fertilizers, Explosives), By Region (North America, Europe, Asia Pacific, CSA, MEA), Competitive Landscape, And Segment Forecasts, 2018 – 2025. Retrieved from Grand View Research: https://www.grandviewresearch.com/industry-analysis/ammonium-nitrate-market

Green, E. M. (2006, june). Explosives regulation in the USA. Retrieved from Crowell: https://www.crowell.com/documents/DOCASSOCFKTYPE_ARTICLES_408.pdf

Health and Safety Executive. (2018). STORING AND HANDLING AMMONIUM NITRATE. Retrieved from Health and Safety Executive: http://www.hse.gov.uk/pubns/indg230.pdf

madehow. (2018). Fertilizer. Retrieved from How Products Are Made: http://www.madehow.com/Volume-3/Fertilizer.html

Pubchem. (2018). Ammonium Nitrate. Retrieved from Pubchem: https://pubchem.ncbi.nlm.nih.gov/compound/ammonium_nitrate#section=Top

Study. (2018). Ammonium Nitrate: Uses & Formula. Retrieved from study.com: https://study.com/academy/lesson/ammonium-nitrate-uses-formula.html

The conversation. (2020). Ammonium nitrate and iodine: a look back at the explosive history of two essential substances. Retrieved from The conversation: https://theconversation.com/ammonium-nitrate-and-iodine-a-look-back-at-the-explosive-history-of-two-essential-substances-146448

United States Environmental Protection Agency. (2018). Ammonium Nitrate. Retrieved from https://www3.epa.gov/ttnchie1/ap42/ch08/final/c08s03.pdf?fbclid=IwAR2ZJNM6V7HjFAQBOoHm6TxQmXDdYT2hzczUF0YEXOQ1uTbT6S7bLRW9xQ8

Dr. Adam Zaidi

Dr. Adam Zaidi, PhD, is a researcher at The University of Manchester (UK). His doctoral research focuses on reducing carbon dioxide emissions in hydrogen production processes. Adam’s expertise includes process scale-up and material development.’

The post Everything You Need To Know About Ammonium Nitrate appeared first on Engineeringness.

SHOP stands for shell higher olefin process and is a chemical process that produces Linear alpha olefins (LAO) from the raw material of ethylene. The SHOP process and mechanism was discovered in 1969 by shell chemists notably Wilhelm Keim in Emeryville California. The SHOP process came at a very important time and its success is due to several factors; the first factor was the cost of producing LAO was high and was only done by using a combination of wax and the Ziegler polymerization, the SHOP overcame the high costs as it processes to produce LAO’s was economically and environmentally better than the wax-splitting and Ziegler methods. Another factor is the demand for ethylene which is produced by the petrochemical industry being far smaller than the supply, thus with the abundance and low cost of ethylene it was the ideal hydrocarbon to use for the SHOP process. Another reason is that in the late 1960’s due to the negative ecological effects of detergents that caused foaming of surface water, theses detergents where being produced from branched fatty alcohols, thus the negative impact of the detergents put pressure on companies such as Shell to innovate and produce a detergent that didn’t cause ecological harm. The SHOP processes solved the ecological issue due to the branched fatty alcohols used in detergents by replacing them with linear fatty alcohols, which worked at lower temperatures and had better washing performances than the detergents that contained branched fatty alcohols (Keim, 2013).

The SHOP process was commercialized by Dutch Shell In 1977 and is used internationally with production exceeding 1 million tonnes annually. LAO are olefins which are alkenes with the general formula CnH2n and are distinguished from other alkenes/olefins due to the carbon double bond being located at the alpha position such as 1-butene and 1-hexene (figure 1).

Figure 1: 1-Butene (left) and 1-Hexene (right) examples of linear alpha-olefins.

Linear Alpha-Olefin Market

The market for LAO is constantly expanding with the highest uses in North America (40%), middle east (19%), Western Europe (16%) and China (10%) (figure 2). From 2012 – 2016 the global consumption of LAO increased by 5.4%, this is due to the increased demand for products that are manufactured using LAO such as; oilfield chemicals, detergents, surfactants and polyethylene comonomers. The projection for the LAO market for the future is an increase of around 3.6% during 2016-2021 with an estimated market value of 15.85 billion by 2023 (PRNewswire, 2018).

One of the main reasons for the projected increase is a new 200,000-tonne production plant being constructed in Qatar, this will increase the current annual global production by approximately 20% (Keim, 2013). Other factors for the projected increase of the alpha-olefins market is due to the continued high demand for alpha-olefins due to the low price of ethylene, the high demand for polyolefin comonomers, the high demand for speciality chemicals and the need for LAO in the oil industry and shale-based natural gases which are the driving force as both of these industries are projected to continue growing and will thus increase the demand for LAO (IHS Markit, 2017).

Figure 2: A Breakdown of SHOP market (IHS Markit, 2017).

Linear Alpha-Olefin Production Methods

LAO’s are produced in two main methods; the first method which is the most popular is the Oligomerization of Ethylene and the second method is the Fischer-Tropsch synthesis. The Oligomerization of Ethylene is the most used process for the production of ethylene as the undesired products that are produced at the end of the process can be recycled till extinction thus this makes the process have very small waste and increases the amount of product produced thus making the process very profitable. Fischer-Tropsch synthesis is used less for the production of LAO’s as Fischer-Tropsch as it produces a range of substance such as; alkanes, alkenes and alcohols. Also, the LAO’s produced must be separated and purified, this will cause the cost of the process to be high as more equipment is needed for the separation and purification. Furthermore, due to the importance of the position of the carbon double bond for LAO production companies will choose SHOP due to SHOP only producing LAO’s.

LAO’s that are produced from the SHOP process has a range of uses; the shorter chain LAO such as C4 – C8 are predominantly used in the production of polyethylene, LAO of chains of C10 – C14 are used in making surfactants for detergents. LAO with chains C16 – C18 is primarily used as a lubricating fluid and LAO with chain C20 and greater which are the least used types of LAO and are used in linear alkylbenzenes, which are used in household detergents as a surfactant (Students, 2015).

The SHOP process (figure 3) converts ethylene into LAO’s by using a variety of catalysts and the three main steps of the SHOP process; oligomerization of ethylene, isomerization and metathesis. The oligomerisation of ethylene this produces alpha-olefins C4-C8, C10-C14 and C16-C40, the desired alpha-olefins can be separated and sold or they C10-C14 alpha-olefins can be turned into alcohols by undergoing linear hydroformylation and then undesired alpha-olefins are sent to the next stage of the process. The second step is the isomerisation of carbon chains C4-C8 and carbon chains of C16-C40 and greater and converts them into internal olefins. The third step and last step is the metathesis which produces new internal olefins with the desired internal olefins C10-C14 being separated by distillation and then undergo hydroformylation and are converted into linear alpha olefins and then into alcohols and the undesired are sent back to isomerization’s part of the process and are recycled to extinction to produce the desired products (ETH Zurich, 2018).

Figure 3: SHOP process diagram schematic (Keim, 2013).

Oligomerization

The oligomerization of ethylene (C2H4) is carried using a homogenous nickel catalyst with a polar solvent at the process conditions of 90-100 ℃ and 40 bar with excess ethylene (Equation 1) (ETH Zurich, 2018). The polar solvent used is 1,4-butanediol, the 1,4-butanediol doesn’t act as a solvent for the products but the reactants and the catalyst, this makes recycling the catalyst easier as the 1,4-butanediol can be separated easily.

Equation 1: oligomerization of ethylene (C₂H₄) using a homogenous nickel catalyst.

The mechanism for oligomerization of ethylene (figure 4) starts with the catalyst precursor being converted into a nickel hydride complex which is the active catalyst intermediate, this is done by using a catalyst precursor which can include oxygen-phosphorus chelate (figure 5). The catalyst precursor has a chelate part and an organic part, the chelate part controls the length of the chain that is produced, and the organic part stabilizes the complex (figure 5) (Rothenberg, 2015). Ethylene is then inserted into the nickel hydride complex; the length of the carbon chain increases due to the insertion of ethylene and then β – hydride elimination occurs which transferrers the hydride atom from the ligand at the beta-position to the metal centre (Interactive Learning Paradigms Incorporated, 2015) thus terminating the chain and produces oligomers of different chain length, polyethylene, wax and regenerates the nickel hydride complex (Rothenberg, 2015).

Figure 4: The mechanism for Oligomerisation of ethylene (Keim, 2013)

Figure 5: examples of catalyst precursors (Hartwig, 2010)

The process of oligomerization of ethylene involves using the nickel catalyst to oligomerize ethylene to produce a broad range of alpha-olefins, the alpha-olefins that are produced are even-numbered and exhibit Flory-Schulz distribution. The alpha-olefins that are produced from the oligomerization of ethylene are then sent separated using distillation, with the alpha-olefins that are desired C4-C10 and C12-C18 being separated and the undesired products being recycled or sent to the next stage of the process which is isomerisation. The Flory-Schulz distribution indicates that oligomerization process favours polymers that are short-chain rather than a long chain, this is extremely useful the alpha-olefins that are produced majority short chain, with 41% being C4-C8 alpha-olefins, 40.5% C10-C18 alpha-olefins and the remaining 18.5% being C20 or greater alpha -olefins (Wittcoff, 2013). Producing these shorter chains alpha-olefins is economically advantageous as the shorter chain alpha-olefins with carbon chains C4-C8 and C10-C18 have direct commercial value and are separated and sold. Furthermore, C10-C14 LAO can undergo hydroformylation, which turns the C10-C14 alpha-olefins into C11-C15 alcohols with an aldehyde intermediate using an octacarbonyl catalyst with ligands such as tributylphosphine (equation 2) (Wittcoff, 2013).

Equation 2: linear hydroformylation of C10 alpha-olefins into C11 alcohol (Wittcoff, 2013)

Isomerization

The next step of the process is isomerisation, this carried out at the process conditions 80 -140 ℃ and 4-20 bar and uses heterogeneous catalysts such as; solid potassium, alkaline alumina or magnesium oxide granules (Hartwig, 2010) and involves the isomerisation of light alpha-olefins (C4-C10) and heavy alpha-olefins (C20+) into internal olefins. Internal olefins have the carbon double bond within the chain and not on the outer carbons. Undertaking isomerisation will cause the alpha-olefins to have the position of the double bonds change position and will result in several internal isomers forming which can be either cis or trans-isomers. This is witnessed in the isomerisation of 1-octene to form a mixture of mainly internal olefins such as 2-octene, 3-octene and 4-octene and a tiny amount of the original alpha-olefin is also found (equation 3) (King Fahd University of Petroleum & Minerals, 2018). After the isomerisation of an alpha-olefin into an internal olefin, the internal olefins are sent to a mixer where they are mixed and are sent to the next stage of the SHOP process where they internal olefins are subjugated to olefin metathesis.

Equation 3: Isomerisation of 1-octene (King Fahd University of Petroleum & Minerals, 2018)

Metathesis

Olefin metathesis causes new carbon double bonds to form, the mixture of short and long-chain internal olefins is passed over an alumina-supported molybdate catalyst that operates at 100-125 ℃ and 10 bar (Mol, 2004), the long and short-chain internal olefins in the mixture then react with one another and produce a statistical distribution of a mixture of linear internal olefins of that include carbon chains which are odd and even (equation 4) (Wittcoff, 2013).

Equation 4: Olefin metathesis of C4 and C20 internal olefins into C12 internal olefins (Wittcoff, 2013).

The species in the catalyst that acts as the active centres for olefin metathesis is the Mo4+ or the Mo5+ (Molybdenum ions). For the formation of the active species the formation of an -allyl complex is important and is the initiation step, and the formation of the active species is by prepared by in situ reductions of the catalyst by the olefin feed (DWYER, 2006). The process of olefin metathesis produces 10-15% of the desired linear internal olefin which has a carbon chain of C10-C14, the desired products are separated from the remaining 85-90% of the undesired products by distillation. The undesired products are then recycled and undergo isomerization and olefin metathesis until extinction. Using this recycling stream more than 96% of the products are C10-C14 linear internal olefin. The desired products form the metathesis stage (C10-C14 linear internal olefin) can undergo two different processes; the first process is linear hydroformylation, this causes linear internal olefins to be converted into linear aldehydes using a catalyst and in the presence of hydrogen. The catalyst is an octacarbonyl catalyst with ligands such as tributylphosphine (Wittcoff, 2013). The catalyst causes the reduction of the aldehyde as it causes the migration of the position of the carbon-carbon double bond to the primary position and then converts the intermediate aldehyde to be converted into C11-C14 alcohols which are used in plasticizers and precursors to detergents, an example of this is converting C12 internal olefins to C14 alcohol (equation 5) (Wittcoff, 2013). The second process involves alkylating the linear internal olefins to creates linear alkylbenzenes, which are used in household detergents as a surfactant (DWYER, 2006).

Equation 5: Linear hydroformylation of C12 internal olefin to C14 alcohol (Wittcoff, 2013).

References

DWYER, C. L. (2006). Metathesis of Olefins. In G. P. Chiusoli, Metal-Catalysis in Industrial Organic Processes (pp. 208-209). Sheffield: RSC publishing.

ETH Zurich. (2018). The Shell Higher Olefins Process (SHOP). Retrieved from ETH Zurich: https://www.ethz.ch/content/dam/ethz/special-interest/chab/icb/van-bokhoven-group-dam/coursework/Catalysis/2018/HomCat4_olefins_Part3_SHOP.pdf

Hartwig, J. F. (2010). Organotransition Metal Chemistry – From Bonding to Catalysis. California: University Science Books.

IHS Markit. (2017, March). Linear Alpha-Olefins. Retrieved from IHS Markit: https://ihsmarkit.com/products/linear-alpha-olefins-chemical-economics-handbook.html

Interactive Learning Paradigms Incorporated. (2015, March 31). Beta-Hydride Elimination. Retrieved from Interactive Learning Paradigms Incorporated: http://www.ilpi.com/organomet/betahydride.html

Keim, W. (2013, October 15). Oligomerization of Ethylene toa-Olefins: Discovery and development of the Shell Higher Olefin Process(SHOP). Retrieved from Wiley Online Library: https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.201305308

King Fahd University of Petroleum & Minerals. (2018). ISOMERIZATION OF OLEFINS. Retrieved from King Fahd University of Petroleum & Minerals: http://faculty.kfupm.edu.sa/chem/belali/CHEM%20620/Chapter%202/CHAPTER%202_ISOMERIZATION%20OF%20OLEFINS.pdf

Mol, J. C. (2004). Industrial applications of olefin metathesis. Journal of Molecular Catalysis A: Chemical, 39-45.

PRNewswire. (2018, July 31). Global $15.85 Billion Alpha Olefins Market by Type, Application and Geography – Forecast to 2023. Retrieved from PR Newswire: https://www.prnewswire.com/news-releases/global-15-85-billion-alpha-olefins-market-by-type-application-and-geography—forecast-to-2023–300689141.html

Rothenberg, G. (2015). Catalysis: Concepts and Green Applications. Amsterdam: Wiley.

Students, I. C.-F. (2015). Industrial Chemistry – For Advanced Students. Detroit: De Gruyter.

Wittcoff, H. (2013). Industrial Organic Chemicals (3rd Edition). New Jersey: Wiley.

Dr. Adam Zaidi

Dr. Adam Zaidi, PhD, is a researcher at The University of Manchester (UK). His doctoral research focuses on reducing carbon dioxide emissions in hydrogen production processes. Adam’s expertise includes process scale-up and material development.’

The post An In Depth Guide To The Shop Process appeared first on Engineeringness.

This article explores the principles behind vapour pressure, including key laws such as Raoult’s Law and the Antoine Equation.

What Is Vapour Pressure?

Vapour pressure is the pressure exerted by the vapour of a substance in thermodynamic equilibrium with its condensed phases (solid or liquid) in a closed system. At a given temperature, the vapour pressure represents the tendency of molecules to escape from the liquid or solid phase into the gaseous phase.

As temperature increases, more molecules have the energy to escape into the vapour phase, leading to an increase in vapour pressure.

This property does not depend upon quantity. It can be calculated by using the Antoine equation which expresses vapour pressure as a function of temperature.

What Is The Antoine Equation?

The Antoine Equation is an empirical relationship that describes the variation of vapour pressure with temperature. It is widely used because of its simplicity and accuracy for a broad range of substances.

Where:

T – Temperature of the liquid or substance

P – Vapour Pressure of a liquid or substance

A, B & C – are liquid or substance specific constants/ coefficients

The equation can be rearranged to calculate temperature as follows:

In fractional distillation, this property plays an important role as the design of the column depends upon vapour pressure differences.

A Brief History of The Antoine Equation

The Antoine Equation was developed by French engineer and chemist Louis Charles Antoine in 1888. Antoine’s work was pivotal in providing a practical tool for engineers and scientists to calculate vapour pressures at different temperatures, especially in the design and operation of distillation columns and other separation processes.

What Are The Units of Vapour Pressure?

In general value of V_p is measured in the same units of pressure. As we know that there are different units available for a measure of pressure like:

• kg/cm²
• PSI
• N/m²
• kPa
• Bar
• Pascal

Factors That Affect Vapour Pressure

Some of the key factors which affect the vapour pressure are:

• Temperature
• Solute concentration and nature
• Boiling point

How Does Temperature Affect Vapour Pressure?

As you increase the temperature of the solid or liquid in a system then its V_p will also increase and vice versa for when it decreases.

How Does Solute Concentration And Nature Affect Vapour Pressure?

If you add more non-volatile solute to dissolve into a volatile solvent then the vapour pressure of the solvent will reduce, hence, in this example the more solute you add the lower the vapour pressure of the solute gets. 

Factors That Do Not Affect Vapour Pressure

Volume

V_p does not increase or decrease with respect to the volume of its system.

Surface Area

The surface area of the solid or liquid in contact with the gas will have no effect on the vapour pressure of the system.

What is Raoult’s Law? 

Raoult’s Law is a principle that relates the vapour pressure of an ideal solution to the vapour pressures of its individual components and their mole fractions. It states that the partial vapour pressure of each component in a solution is proportional to its mole fraction in the solution and its vapour pressure when at the same temperature. It can be represented in the formula below:

Where:

P_solution – Vapour Pressure of the solution

X_solvent – Mole fraction of the solvent

P_solvent – Vapour Pressure of the pure solvent

Raoult’s law can be used to estimate the contribution of individual components of a liquid or solid mixture to the total pressure exerted by the system.

We can use Raoult’s Law to calculate the vapour pressure of a given liquid. So Raoult’s Law is very helpful in the design of distillation columns. Using Raoult’s Law we can calculate the required temperature under a given vacuum in a distillation system.

A Brief History of Raoult’s Law

Raoult’s Law was first discovered by French chemist François-Marie Raoult in 1887. Raoult’s work on the connecting properties of solutions, such as freezing point depression and boiling point elevation, led to the development of this law. Although Raoult’s Law applies strictly to ideal solutions, it laid the groundwork for understanding the behaviour of real solutions, particularly in chemical engineering and thermodynamics.

Vapour Pressure of Water

At 25 degrees Celsius, the vapour pressure of water is 23.8 mmHg. At 100 degrees Celsius, water reaches its boiling point, and the vapour pressure becomes equal to one atmosphere (which is equivalent to 760 mmHg).

Hassan Ahmed

Hassan graduated with a Master’s degree in Chemical Engineering from the University of Chester (UK). He currently works as a design engineering consultant for one of the largest engineering firms in the world along with being an associate member of the Institute of Chemical Engineers (IChemE).

The post A Comprehensive Guide to Vapour Pressure | Understanding Key Laws and Their Applications appeared first on Engineeringness.

Water softening is used to remove the hardness from water, which is primarily caused by the presence of minerals like calcium and magnesium. The use of water softening has several benefits:

• Prevention of Scale Buildup: Hard water can lead to the accumulation of scale inside pipes, boilers, and appliances like washing machines and water heaters, which can reduce their efficiency and lifespan.
• Improved Cleaning: Soft water enhances the effectiveness of soap and detergents, resulting in cleaner dishes, laundry, and surfaces, and can reduce the amount of soap needed for tasks.
• Appliance Longevity: Appliances that use water, like dishwashers and coffee makers, last longer and work more efficiently when scale buildup is minimized by using softened water.
• Better Water Quality: Softened water can improve the taste and smell of drinking water in some cases, especially if the hardness was causing a noticeable taste or odor.
• Skin and Hair Health: Hard water can leave skin feeling dry and hair looking dull due to excess minerals. Soft water can alleviate these issues, leading to softer skin and more manageable hair.

Water softening is thus an important process for residential, commercial, and industrial settings to protect infrastructure and improve the efficiency and effectiveness of cleaning and heating processes.

What Is Ion Exchange?

Ion exchange serves a broad spectrum of applications, yet it is chiefly employed for water softening by employing gel resins. This process is done in a cyclical sequence within a fixed bed, made up of four primary phases, Loading phase, Displacement Phase, Regeneration phase and finally Washing Phase.

Ion Exchange Phases In Water Softening

Loading Phase

In this initial step, the solution flowing through the resin bed undergoes ion exchange. The resin selectively absorbs divalent cations, specifically calcium (Ca2+) and magnesium (Mg2+), from the water. As a result of this exchange, an equivalent amount of sodium ions (Na+) is released from the resin into the water. The efficiency of this phase hinges on the rate at which equilibrium between the resin and the solution is achieved. The desired outcome is the effective replacement of hardness-causing ions with sodium ions from the resin, thereby softening the water.

Displacement Phase

Following the loading phase, the next step involves preparing the resin for regeneration. This is done by displacing the ions that have accumulated during the loading phase with a concentrated sodium chloride solution, facilitating the removal of divalent cations from the resin sites. The goal is to prepare the saturated resin for regeneration by displacing the hardness ions with a high concentration brine solution.

Regeneration Phase

During this critical step, the previously absorbed divalent ions are replaced by sodium ions from the regenerating solution. This replenishes the resin’s ion exchange capacity, making it ready for another cycle of ion exchange. The aim here is to restore the ion exchange capacity of the resin by replacing the hardness ions with sodium ions, using a concentrated salt solution.

Washing Phase

The final stage of the cycle entails thoroughly washing the resin to eliminate any residual regenerating solution. This ensures that the resin is clear of high-concentration sodium ions, which could otherwise contaminate the softened water in the subsequent loading phase. The final objective is to remove any excess brine from the resin, ensuring it is ready for the next cycle without introducing excessive sodium into the treated water.

This ion exchange cycle is optimally modeled when the mass transfer between the solution and the resin is rapid, allowing for the system to reach equilibrium quickly, a condition often described by a specific equilibrium expression. This expression accounts for the selectivity of the resin towards divalent over monovalent ions, ensuring a favorable exchange process.

The progression of the ion exchange is well approximated using simple stoichiometric or shock-wave front theory for adsorption, assuming plug flow. This means that the front of the ion exchange wave moves down through the bed in a uniform front, with the resin behind or upstream of the front remaining in equilibrium with the feed composition. The end of the cycle is marked by a breakthrough when the ion exchange front reaches the end of the bed, indicating that the bed’s capacity for ion exchange has been fully utilized and necessitates regeneration.

Adrian Michaels

Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).

The post Unlocking the Full Potential of Water Softening | Harnessing Ion Exchange For Superior Water Quality appeared first on Engineeringness.

• Fluid bed drying is a highly efficient method of drying various materials.
• It involves suspending the material in a fluidized state, allowing for rapid and uniform drying.
• Fluid bed dryers are commonly used in industries such as pharmaceuticals, food processing, and chemicals.
• They offer advantages such as reduced drying time, improved product quality, and energy efficiency.
• Proper maintenance and monitoring are essential for optimal performance and safety of fluid bed dryers.

Introduction

Fluid bed drying is a widely used technique in various industries for drying different types of materials. It offers numerous advantages over traditional drying methods, making it a preferred choice for many manufacturers. This article will explore the concept of fluid bed drying, its applications, benefits, and maintenance requirements.

The Science Behind Fluid Bed Drying

Fluid bed drying operates on the principle of fluidization, which involves suspending solid particles in a fluidized state. In this process, a gas or liquid is passed through a bed of solid particles, causing them to behave like a fluid. The fluidization creates a highly efficient heat and mass transfer environment, allowing for rapid and uniform drying of the material.

Applications of Fluid Bed Drying

Fluid bed drying finds extensive use in various industries due to its versatility and efficiency. Some common applications include:

1. Pharmaceutical Industry

In the pharmaceutical industry, fluid bed dryers are used for drying granules, powders, and pellets. This drying method ensures uniform drying and prevents the formation of lumps or agglomerates. It is crucial for maintaining the quality and stability of pharmaceutical products.

2. Food Processing

Fluid bed drying is employed in the food processing industry for drying fruits, vegetables, grains, and other food products. It helps in preserving the nutritional value, flavor, and texture of the food while removing excess moisture. This method is particularly useful for producing dehydrated fruits and vegetables.

3. Chemical Industry

The chemical industry utilizes fluid bed dryers for drying various chemicals, including fertilizers, pigments, and catalysts. The uniform drying achieved through fluid bed drying ensures consistent product quality and reduces the risk of chemical reactions or degradation.

Advantages of Fluid Bed Drying

Fluid bed drying offers several advantages over conventional drying methods:

1. Reduced Drying Time

Fluid bed drying allows for rapid and efficient drying due to the increased surface area and enhanced heat transfer. This results in shorter drying cycles and increased productivity for manufacturers.

2. Improved Product Quality

Fluid bed drying ensures uniform drying, preventing the formation of hot spots or uneven moisture distribution. This leads to improved product quality, consistency, and reduced risk of spoilage or degradation.

3. Energy Efficiency

Fluid bed dryers require less energy compared to other drying methods due to their efficient heat transfer mechanism. The fluidization process minimizes heat loss and maximizes energy utilization, resulting in cost savings for manufacturers.

4. Versatility

Fluid bed dryers can handle a wide range of materials, including powders, granules, crystals, and even heat-sensitive substances. This versatility makes them suitable for diverse industries and applications.

5. Easy Scale-up

Fluid bed drying can be easily scaled up or down to accommodate different production volumes. Manufacturers can adjust the size and capacity of the fluid bed dryer to meet their specific requirements without significant modifications.

Maintenance and Safety Considerations

Proper maintenance and monitoring are essential for ensuring the optimal performance and safety of fluid bed dryers. Some key considerations include:

1. Regular Cleaning

Fluid bed dryers should be cleaned regularly to remove any accumulated particles or residues. This helps maintain the efficiency of the drying process and prevents contamination of subsequent batches.

2. Inspection of Components

All components of the fluid bed dryer, including filters, fans, and heating elements, should be inspected periodically for wear and tear. Any damaged or malfunctioning parts should be replaced promptly to avoid operational issues.

3. Temperature and Pressure Monitoring

Monitoring the temperature and pressure inside the fluid bed dryer is crucial for safe and efficient operation. Regular checks and calibration of sensors and gauges should be performed to ensure accurate readings.

4. Training and Safety Protocols

Operators should receive proper training on the operation and maintenance of fluid bed dryers. They should also follow established safety protocols to prevent accidents or injuries during operation.

Conclusion

Fluid bed drying is a highly efficient and versatile method for drying various materials in industries such as pharmaceuticals, food processing, and chemicals. It offers advantages such as reduced drying time, improved product quality, and energy efficiency. However, proper maintenance and monitoring are crucial for optimal performance and safety. By understanding the science behind fluid bed drying and implementing appropriate maintenance practices, manufacturers can harness the benefits of this drying technique and enhance their production processes.

Adrian Michaels

Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).

The post Fluid Bed Drying: Efficient and Versatile Drying Method appeared first on Engineeringness.

• The FBD process is a widely used method in the pharmaceutical industry for drying and granulation.
• It involves the use of a fluidized bed to suspend and agitate particles, allowing for efficient drying and granulation.
• The FBD process offers several advantages, including uniform drying, improved product quality, and reduced drying time.
• Proper control and monitoring of process parameters are crucial for achieving optimal results in the FBD process.
• Regular maintenance and cleaning of the fluidized bed equipment are essential to ensure its efficient operation.

Introduction

The FBD (Fluidized Bed Drying) process is a widely used technique in the pharmaceutical industry for drying and granulation. It involves the use of a fluidized bed, where particles are suspended and agitated by a stream of air or gas. This article will explore the FBD process in detail, discussing its principles, applications, advantages, and key considerations for optimal operation.

Principles of the FBD Process

The FBD process operates on the principle of fluidization, where a bed of solid particles is transformed into a fluid-like state by passing a gas or liquid through it. In the case of the FBD process, air or gas is used to fluidize the bed of particles. This fluidization creates a turbulent and agitated environment, allowing for efficient heat and mass transfer.

Fluidization and Particle Suspension

When the gas or air velocity is increased, it reaches a point where the drag force exerted on the particles overcomes their weight, causing them to become suspended in the fluidized bed. This suspension allows for uniform contact between the particles and the drying or granulating medium, ensuring efficient heat and mass transfer.

Heat and Mass Transfer

The fluidized bed provides an ideal environment for heat and mass transfer due to its high surface area and efficient mixing. As the particles are suspended and agitated, the drying or granulating medium can penetrate the bed, rapidly transferring heat to the particles and evaporating moisture. Similarly, during granulation, the binder solution can evenly coat the particles, leading to uniform granule formation.

Applications of the FBD Process

The FBD process finds extensive applications in the pharmaceutical industry, particularly in the drying and granulation of pharmaceutical powders and granules. Some common applications include:

Drying of Active Pharmaceutical Ingredients (APIs)

The FBD process is widely used for drying APIs, ensuring their stability and shelf-life. The fluidized bed allows for uniform drying, preventing the formation of hot spots and ensuring consistent product quality.

Granulation of Pharmaceutical Powders

The FBD process is also employed for granulation, where fine powders are transformed into granules with improved flowability, compressibility, and uniformity. The fluidized bed facilitates the even distribution of the binder solution, leading to uniform granule formation.

Advantages of the FBD Process

The FBD process offers several advantages over other drying and granulation methods:

Uniform Drying

The fluidized bed ensures uniform contact between the drying medium and the particles, resulting in uniform drying throughout the bed. This eliminates the risk of over-drying or under-drying, leading to consistent product quality.

Improved Product Quality

The FBD process allows for precise control over process parameters, such as temperature, airflow, and residence time. This control ensures that the drying or granulation process is optimized, leading to improved product quality with desired characteristics.

Reduced Drying Time

The efficient heat and mass transfer in the fluidized bed significantly reduce the drying time compared to other methods. This not only improves productivity but also minimizes the risk of degradation or loss of volatile components in the product.

Considerations for Optimal FBD Process

To achieve optimal results in the FBD process, several key considerations should be taken into account:

Process Parameters

Proper control and monitoring of process parameters, such as temperature, airflow, and residence time, are crucial for achieving the desired drying or granulation outcomes. Regular calibration and adjustment of equipment are necessary to maintain optimal process conditions.

Equipment Maintenance

Regular maintenance and cleaning of the fluidized bed equipment are essential to ensure its efficient operation. This includes cleaning the filters, inspecting the nozzles, and checking for any signs of wear or damage. Proper maintenance helps prevent equipment malfunction and ensures consistent performance.

Conclusion

The FBD process is a widely used method in the pharmaceutical industry for drying and granulation. It offers several advantages, including uniform drying, improved product quality, and reduced drying time. Proper control and monitoring of process parameters, as well as regular equipment maintenance, are crucial for achieving optimal results in the FBD process. By understanding the principles and applications of the FBD process, pharmaceutical manufacturers can enhance their drying and granulation processes, leading to high-quality products and improved efficiency.

Adrian Michaels

Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).

The post The FBD Process: Drying and Granulation in Pharmaceuticals appeared first on Engineeringness.

Key Takeaways

– Fiberglass springs are a type of spring made from fiberglass material.
– They offer several advantages over traditional metal springs, including lightweight, corrosion resistance, and high strength.
– Fiberglass springs are commonly used in various industries, such as automotive, aerospace, and sports equipment.
– The manufacturing process of fiberglass springs involves the use of fiberglass strands and resin to create a strong and flexible composite material.
– Proper maintenance and care are essential to ensure the longevity and performance of fiberglass springs.

Introduction

Springs are an essential component in many mechanical systems, providing support, cushioning, and flexibility. Traditionally, springs have been made from metal materials such as steel or bronze. However, with advancements in technology and materials, fiberglass springs have emerged as a viable alternative. In this article, we will explore the world of fiberglass springs, their advantages, applications, and the manufacturing process behind them.

Advantages of Fiberglass Springs

Fiberglass springs offer several advantages over their metal counterparts. One of the key benefits is their lightweight nature. Fiberglass is a composite material made from glass fibers and resin, resulting in a significantly lighter spring compared to metal springs. This weight reduction can have a positive impact on various applications, such as automotive and aerospace industries, where reducing overall weight is crucial for fuel efficiency and performance.

Another advantage of fiberglass springs is their corrosion resistance. Unlike metal springs, fiberglass springs are not susceptible to rust or corrosion, making them ideal for outdoor or marine applications. This corrosion resistance ensures the longevity and durability of the springs, even in harsh environments.

In addition to being lightweight and corrosion-resistant, fiberglass springs also offer high strength. The composite nature of fiberglass allows for a combination of flexibility and strength, making them suitable for applications that require both. This strength is particularly beneficial in industries such as sports equipment, where fiberglass springs are used in various sporting goods like tennis rackets and archery bows.

Applications of Fiberglass Springs

Fiberglass springs find applications in a wide range of industries. One of the most common uses is in the automotive industry, where they are used in suspension systems. The lightweight nature of fiberglass springs helps reduce the overall weight of the vehicle, improving fuel efficiency and handling. Additionally, their corrosion resistance ensures a longer lifespan, reducing maintenance costs.

The aerospace industry also benefits from the use of fiberglass springs. They are used in aircraft landing gear systems, providing shock absorption and support during takeoff and landing. The lightweight and high strength properties of fiberglass springs contribute to the overall performance and safety of the aircraft.

Sports equipment manufacturers have also embraced fiberglass springs in their products. Tennis rackets, for example, utilize fiberglass springs in the form of composite frames, providing a balance of flexibility and strength for optimal performance on the court. Archery bows also benefit from fiberglass springs, offering improved accuracy and power.

Apart from automotive, aerospace, and sports equipment, fiberglass springs are used in various other applications. These include industrial machinery, marine equipment, and even furniture manufacturing. The versatility of fiberglass springs makes them a popular choice across different industries.

Manufacturing Process of Fiberglass Springs

The manufacturing process of fiberglass springs involves several steps to create a strong and flexible composite material. It starts with the selection of high-quality fiberglass strands, which are typically made from glass fibers coated with a protective resin. These strands are then woven together to form a mat or fabric.

Next, the fiberglass fabric is impregnated with a resin, typically epoxy or polyester, to create a composite material. The resin acts as a binding agent, holding the fiberglass strands together and providing additional strength. The impregnated fabric is then shaped into the desired spring form using molds or other shaping techniques.

Once the spring shape is achieved, the composite material is cured or hardened through a process called polymerization. This process involves subjecting the spring to heat or ultraviolet light, allowing the resin to fully cure and bond with the fiberglass strands. The resulting fiberglass spring is then trimmed, finished, and inspected for quality control.

Conclusion

Fiberglass springs offer a range of advantages over traditional metal springs, making them a popular choice in various industries. Their lightweight nature, corrosion resistance, and high strength properties make them ideal for applications where weight reduction, durability, and performance are crucial. From automotive suspension systems to aerospace landing gear and sports equipment, fiberglass springs have proven their worth. Understanding the manufacturing process behind fiberglass springs helps appreciate the intricate engineering and craftsmanship involved in creating these versatile components. Proper maintenance and care are essential to ensure the longevity and optimal performance of fiberglass springs, making them a reliable choice for many mechanical systems.

Adrian Michaels

Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).

The post The Advantages and Applications of Fiberglass Springs appeared first on Engineeringness.

Aircraft bleed air is the source for the inerting gas that is used to inert the fuel tank. The bleed air is compressed air taken for the from high or low engine compressor stages of the gas turbine upstream of the fuel-burning stage (Figure 1) (Airbus, 2018). Upon exit of the compressor, the bleed air is at a pressure of 40 PSI and temperature of 200-250, due to this high temperature the bleed air needs cooling down, this is done by using compression and expansion turbines or air-cooled heat exchangers to reduce the temperature, as it is far too hot for the cabin and in the fuel inerting system if the bleed air was introduced at 200-250 degrees, it would cause the fuel to burn in the fuel tank and damage the fuel tank (Skybrary, 2019).

Issues With Bleed Air

Bleed air isn’t without its issues, cases of bleed air leakage are rare and are considered abnormal in the aviation industry. The major threat of bleed air is the risk of a leak of which can lead to overheating, a loss of system functions, melting of aircraft components, the release of emissions of ozone and other gases in the bleed air stream lead to environmental damage (Shao, 2018), noxious fumes can be released into the cabin and a fire could break  out (AOPA, 2011). Furthermore, the high demand for Nitrogen needed from the bleed air which can cause strain on the bleed air system due to the need for maintaining ullage oxygen concentration below 12%.

Fuel Weight Penalty

The uses of bleed air for fuel inerting leads to a large fuel weight penalty. Fuel weight penalties are factors that influence an aircraft’s performance due to added weight, external and momentum drag and performance changes (SAE International, 2004). The issues with using bleed air are high demand of bleed air required to inert the fuel tank which requires the engines to draw in more air which puts more stress on smaller aircraft that have smaller engines and struggle to draw in enough air which leads to greater fuel consumption. Also, with the components of the OBIGGS such as heat exchanges, valves and pipework, this adds weight and requires greater fuel consumption which adds to flying costs for airliners.

The bleed air required to inert the fuel tank changes at different stages of an aircraft’s flight, the stages are; low for climbing and cruising, medium in approach and high in descent (Airbus, 2009). During high and medium phases, the requirement for bleed air is large and this puts a huge strain on an aircraft bleed air system with smaller aircraft struggling much more than larger aircraft due to their smaller bleed air systems, these high bleed air demands require more fuel to be consumed to meet the requirements for inerting which cause a fuel weight penalty (Moir, 2020).

Inerting Methods

The methods used to inert a fuel tank are one of two methods; ullage washing and fuel scrubbing (Federal Aviation Administration, 1998).

• Ullage washing involves injecting an inert gas usually Nitrogen into the ullage of the fuel tank, which displaces the oxygen in the ullage space.

• Fuel scrubbing comprises of small inert gas bubbles being sent into the bottom of the fuel tank and rising to the top and displacing the dissolved oxygen with the dissolved oxygen being removed and dissolved Nitrogen being added which reduces the concentration of oxygen that is in the ullage (Administration, Fuel Tank Protection, 2019).

Inerting Technologies  

Several fuel inerting technologies that are not suitable for commercial aircraft, such as; the Halon Extinguishing System is very expensive, Explosive Resistant Foam adds a lot of weight leading to a fuel weight penalty and Liquid Nitrogen System that requires frequent resupplying and has logistical issues (Yan, 2014). A breakthrough was perceived when OBIGGS was developed which is cheaper than the other inerting technologies and was lightweight, doesn’t have any major logistical issues, requires few moving parts, is highly reliable (Shao, 2018), don’t require pre-flight or post flights checks and can be monitored by aircraft crew by onboard computers (Figure 2) (Smith, 2014). 

OBIGGS

The OBIGGS system works by inerting the fuel tank with Nitrogen-enriched air (NEA) which is 90-98% pure Nitrogen (Figure 3) (Burns, 2004) and reduces the risk of the oxygen concentration rising above 12% which is the upper limit imposed by the FAA for civilian aircraft for ullage oxygen concentration, as any higher oxygen concertation can lead to combustion and by removing one part of the fire triangle which is an oxygen supply no combustion can occur thus no explosion can occur. The inert gas is produced from the aircraft bleed air and ASM that contains hollow fibre membranes (Figure 4) (Smith, 2014) that separate the Nitrogen which is used to inert the fuel tank (Yan, 2014). 

References

Administration, F. A. (2019). Fuel Tank Protection. Retrieved from Federal Aviation Administration: https://www.fire.tc.faa.gov/Systems/FuelTank/Ullage

AOPA. (2011, March 1). SYSTEM SYNOPSIS: BLEED AIR MALFUNCTIONS KNOWING WHAT TO DO WHEN HOT BLEED AIR BECOMES TOO HOT. Retrieved from AOPA: https://www.aopa.org/news-and-media/all-news/2011/march/01/system-synopsis-bleed-air-malfunctions

Federal Aviation Administration. (1998). Fuel Tank Inerting. Atlantic City: Federal Aviation Administration.

Moir, A. S. (2020). Design and Development of Aircraft Systems Third Edition . Chichester: Wiley.

Smith, D. E. (2014). FUEL TANK INERTING SYSTEMS FOR CIVIL AIRCRAFT. Retrieved from mountainscholar: https://mountainscholar.org/bitstream/handle/10217/88618/Smith_David_colostate_0053N_12699_rev.pdf?sequence=1

Dr. Adam Zaidi

Dr. Adam Zaidi, PhD, is a researcher at The University of Manchester (UK). His doctoral research focuses on reducing carbon dioxide emissions in hydrogen production processes. Adam’s expertise includes process scale-up and material development.’

The post A Breakdown | Aircraft Fuel Inerting appeared first on Engineeringness.

The reaction rate, r_i (also referred to as the rate of reaction) is a measure of how fast a reaction is and is defined using several ways:

$r_i = \frac{1}{V}\frac{∆N_i}{∆t} = \frac{Moles of species ‘i‘ formed}{Volume of fluid \times time}$

${r_i}^{‘} = \frac{1}{M}\frac{∆N_i}{∆t} = \frac{Moles of species ‘i‘ formed}{Mass of solid \times time}$

${r_i}^{‘‘} = \frac{1}{S}\frac{∆N_i}{∆t} = \frac{Moles of species ‘i‘ formed }{Surface area \times time}$

${r_i}^{‘‘‘} = \frac{1}{V_s}\frac{∆N_i}{∆t} = \frac{Moles of species ‘i‘ formed}{Volume of solid \times time}$

${r_i}^{‘‘‘‘} = \frac{1}{V_r}\frac{∆N_i}{∆t} = \frac{Moles of species ‘i‘ formed}{Volume of reactor \times time}$

One of the benefits of the reaction rate is that if the reactor is scaled up the rate of reaction will be the same, which simplifies the process of reactor scale up, so no long equations are needed every time the reactor volume changes. Thus, the reaction rate is an intensive quantity as its magnitude is independent of the size of the system (i.e. changing reactor size).

For reagents, reaction rates are negative and for products the reaction rates are positive, this is because reagents are used up in reactions, and products are formed. An example of this would be the reaction:

$aA + bB \to \mathrm{cC}$

to write this out in terms of reaction rates, the species (A, B, or C) and the stoichiometric coefficient (a, b and c) are required, and the concept stated above: the reagents being negative and the products being positive.

$–\frac{r_A}{a} = –\frac{r_B}{b}=\frac{r_C}{c}$

(1.0)

Example: To prove that the reactions rates are equal

A reactor with fluid volume 1 m³ has a reaction with the reaction time being 10 seconds, and we are told that 5 moles of B are formed, prove that the rates are equal.

Hint: use the reaction rate definitions, looking closely at parameters you have been given and equation 1.0.

Show Answer

Rate Equations

For any chemical reaction equation, a rate equation can be used which links the forward reaction rate with the concentration or pressure of the reactants. These are more complicated functions of reagents and (sometimes) product concentrations for a non-elementary reaction.

Reactions can be classified under these terms:

• Homogeneous: consists of only one phase
• Heterogeneous: more than one phase needed for the reaction
• Catalytic or noncatalytic
• Exothermic or endothermic
• Elementary or nonelementary
• Single reaction or multiple reactions (and within latter: series or parallel, and combinations)

Writing out a rate equation:

Taking an example reaction:

$A + B \to \mathrm{C}$

The rate equation would simply be:

$–r_A = K_A{C}_A^a{C}_B^b$

And using equation 1.0 we know that the rate equation concerning species B would be the same as that of species A. K is the rate constant which is proportionally constant that indicates the relationship between the molar concentration of reactants and the rate of a chemical reaction (Helmenstine, 2018), and the rate constant concerning each species is:

$\frac{K_A}{a}=\frac{K_B}{b}$

Given a rate equation:

$–r_A = K_A{C}_A^a{C}_B^b$

The reagents a and b are not always the stoichiometric coefficients, we say that the reaction n order concerning A and b^th order concerning B and the overall order is n = a + b.

The molecularity of an elementary reaction is the number of molecules involved in the reaction. The order can be fractional values and molecularity is always a whole number.

Equilibrium Constant

For an equilibrium reaction, the rate of the forward reaction is the same as the rate of the backward reaction and the concentration doesn’t change.

$–r_{A, forwards }= r_{A, backwards}$

(1.2)

For the reaction:

$\mathrm{aA} + \mathrm{bB} \rightleftharpoons \mathrm{cC} + \mathrm{dD}$

The equilibrium constant K_C (also written as K_eq or K) can be defined as:

$K_C = \frac{{\left[C\right]}_{eq}^c{\left[D\right]}_{eq}^d}{{\left[A\right]}_{eq}^a{\left[B\right]}_{eq}^b}$

(1.3)

The position of the equilibrium is determined by the entropy change, the enthalpy change, and the conditions the reaction is under such as temperature and pressure.

Assuming the reaction is elementary (stoichiometric coefficients are usually 1 for all species) the forward and backward reaction can be stated:

$r_{A, forwards }= –k_1{\left[A\right]}^a{\left[B\right]}^b$

$r_{A, backwards} = k_{–1}{\left[C\right]}^c{\left[D\right]}^d$

k₁ represents the rate constant for the backward reaction and k_-1 represents the rate constant for the forward’s reaction

Thus, we can know to prove equilibrium constant K_C equation 1.3, by first using equation 1.2:

$–k_1{\left[A\right]}_{eq}^a{\left[B\right]}_{eq}^b = k_{–1}{\left[C\right]}_{eq}^c{\left[D\right]}_{eq}^d$

when rearranged will give:

$K_C = \frac{{\left[C\right]}_{eq}^c{\left[D\right]}_{eq}^d}{{\left[A\right]}_{eq}^a{\left[B\right]}_{eq}^b}$

References

Helmenstine, A. M. (2018, September 27). What Is the Rate Constant in Chemistry? Retrieved from ThoughtCo: https://www.thoughtco.com/reaction-rate-constant-definition-and-equation-4175922

Dr. Adam Zaidi

Dr. Adam Zaidi, PhD, is a researcher at The University of Manchester (UK). His doctoral research focuses on reducing carbon dioxide emissions in hydrogen production processes. Adam’s expertise includes process scale-up and material development.’

The post An In Depth Guide To Basic Reaction Kinetics appeared first on Engineeringness.