Pumps nptel pdf download

Akshay Kumbhar , Student at Dr. Patil Pratishthan's Padmashree Dr. Patil Institute Of Engineering and Technology. Yengandul Balrajbhai. Show More. Views Total views. Actions Shares. No notes for slide. Centrifugal pump lecture 1 1. Impulse, Buoyancy A collection chamber in the casing converts much of the Kinetic Energy energy due to velocity into Head or Pressure. Impellers Head The point on the system curve that intersects the pump curve is known as the operating point. Pump Flow Rate Thank You.

Total views 14, On Slideshare 0. From embeds 0. Number of embeds Downloads Shares 0. Comments 0. Likes Week 2 : Radial and axial flow pumps. Week 3 : Radial flow pump operational issues. Week 4 : Pump Design: Degrees of reaction. Week 5 : Pump characteristics and system design.

Week 7 : Hydraulic Turbine: Impulse Turbine. Week 8 : Hydraulic Turbine: Reaction Turbine. Books and references 1. Douglas, J. Gasiorek, J. Swaffield and L. Jack, Fluid Mechanics, Pearson Education, Ans: To avoid the formation of other compounds during cracking. Vinyl chloride cracking is a very selective cracking that we wish to happen. The selective cracking needs very clean feed stock. Why quenching is carried out? Ans: The selective cracking reaction is a reversible reaction.

Therefore, by doing cold ethylene dichloride quenching, we are suppressing the backward reaction and ensuring that only vinyl chloride gets formed in good quantities. Can heat integration be carried out in the process?

Ans: IN principle it can be done but in reality no. The reason is that if quenching is not done immediately, then vinyl chloride can get converted back to the ethylene dichloride. Therefore, though there is a hot stream available, heat integration cannot be done due to prevalent process conditions. Can a partial condenser be used in the last distillation column to serve for both quenching, distillation reflux and produce vapour for the ethylene dichloride?

Ans: Yes, this arrangement will be excellent as all requirements in the process will be met by going for a partial condenser. But it all depends on the quenching tower requirements and hence if ethylene dichloride needs to be cooled more than its boiling point, then partial condenser will not serve the purpose. What is the effect of pressure on quenching. This question is interesting as the reaction occurs at 4 atm and quenching occurs at higher pressure?

Ans: Quenching is an operation used for minimizing temperature. As such its not absorption where pressure plays an important role. As such, the effect of pressure will not be significant in the quenching operation. A dowtherm fluid is a heat transfer fluid , which is a mixture of two very stable compounds, biphenyl and diphenyl oxide.

The fluid is dyed clear to light yellow to aid in leak detection. The regenerated water reaches the absorber through a heat integrated exchanger. The heavy ends are obtained as bottom product. What is Dowtherm? Ans: Dowtherm is an organic liquid that can attain to temperatures upto o C.

In this example, the operating temperature is about - oC and therefore usage of Dowtherm fluid is perfect. In what way compression is beneficial to the absorption? Ans: It is a known fact that absorption is most favoured at low temperature and high pressure. Therefore, compression of the cooled product gases will be very beneficial to maximize the dissolution of ethylene oxide in the water.

Of course, along with ethylene oxide other light ends and heavy ends also dissolve in water and we have no control over that. Why again another compressor is used before the stripper? Ans: The second compressor aids to enhance the boiling points of the mixtures. Thereby, water can be used as a cooling fluid in the distillation columns, as the boiling point of the products is enhanced by compression.

In this regard, it should be noted that ethylene oxide has a boiling point of Why ethylene and air are separately compressed? Ans: This is due to the danger of generating an explosive mixture during compression step of the mixture.

What process modifications are possible for the flowsheet? Discuss the energy integration capacity of the process? Ans: In this process, the heat integration drastically reduced process steam requirements.

Steam is only required in the strippers and fractionators. This steam can be generated using waste heat recovery units using dowtherm fluid as the hot fluid to generate the steam.

Thus in this process, it is observed that for 1 ton of ethylene oxide produced, only 0. This is all possible due to significant heat integration in the process.

Therefore, the reaction will be gas-liquid reaction - Ethylene oxide is the limiting reactant The bottom product from the last distillation tower is the heavy ends product. Ans: Liquids have higher mass transfer coefficients than solids. Therefore, if the reaction needs be facilitated with two components, if they are in liquid phases, then reactions could be faster. Therefore, pressure can play an important role in both altering the selectivity as well as conversion of the series reactions scheme.

Ans: Ammonia dissolves instantaneously in water to form ammonia solution. This chemical affinity of ammonia is very difficult to get it through. On the other hand, despite using flash unit, some ammonia will remain the water consisting of ethanolamines and heavy ends.

Why vacuum is used in the second and third distillation towers? Ans: The diethanol and triethanolamines dissociate at high operating temperatures. Therefore, vacuum is used to reduce the operating temperature of the distillation columns second and third. What process modifications you can suggest for better operation? Ans: When higher quantitites of di or triethanolamine is desired, then the monoethanolamine can be sent to another reactor in which ethylene oxide is added.

Can solvents extraction be used instead of vacuum distillation for the separation of di and triethanolamines? Ans: No, this is due to the reason that solvents tend to have similar solubility factors for both di and triethanolamines. Here, sulfonation reaction takes place.

Jacketed arrangement will be preferred for the tray absorption column to circulate the refrigerated brine in the cooling jacket. Subsequently, pure propylene is sent to mix with the fresh feed stream. Before sending to the unit, the propylene is cooled to room temperature so as to have identification conditions as the fresh feed stock. The top product is a mixture of isopropyl ether and water.

The top product is a low boiling azeotrope. This stream upon gravity settling will produce the isopropyl ether as the top product which is sent as a reflux stream to the azeotropic column. The bottom product is a mixture of isopropanol and water is recycled back to the isopropyl alcohol column along with the bottom product generated from the ether separating column.

It finds use in pharmaceutical applications because of the low toxicity of any residues. Isopropanol is also used as a chemical intermediate in some industrial processes. It is also used as a gasoline additive. Why refrigerated brine is used in the sulfonation reactor? Ans: The reaction temperature is room temperature 25 — 30 oC. Therefore, refrigerated fluid is used. Brine is used here, as refrigerated is antifreeze and can allow solution to reach lower temperatures without freezing problem.

Ans: Apart from costs, the total condenser produces a single stream and this is of no use as propylene must be separated and sent as a gas back to the sulfonation reactor. All this is achieved in a single process unit by using partial condensation principle. Why is isopropyl ether circulated back to the sulfonation reactor?

Ans: To suppress the side reaction and hence decomposition of sulfonation to less valued product. Present the working principle of an azeotropic distillation column? Ans: The azeotropic distillation column is fed with the azeotrope mixture and another component which forms a low boiling heterogenous azeotrope with the feed azetropic mixture components as one of the products and a purer compound as the other product.

The low boiling azeotrope is then sent to a gravity settler that separates the heterogeneous phases into two products namely the azeotropic agent and an impure mixture of the original components.

The impure mixture is actually fed to one of the distillation columns in the process flow sheet at a location that matches with the purity of the stream.

What happens to the water in which acid gets dissolved in the hydrolyzer cum stripper column? Ans: Here, the stream is a weak acid stream that is fed to a multiple effect evaporator to concentrate the weak acid solution to a strong acid solution. The strong acid solution then can be used as one of the raw materials in the process. Can you do heat integration for the partial condenser with the sulfonation reactor?

Ans: No, the reason is that sulfonation reaction is highly exotermic and heat needs to be quickly removed. This is not possible when vapors are used as the cooling stream as gas phase heat transfer coefficients are significantly lower than the liquid phase heat transfer coefficients. Can a partial condenser be used for the ether column? Ans: Yes, the reason is that there is no hard and fast rule that isopropyl ether be added in the liquid phase to the sulfonation reactor.

In fact, it should be added as a vapour phase only and therefore, partial condenser should be used in place of total condenser to save costs as well as meet the process specifications. The tube is packed with the porous copper catalyst - The reactor is operated at — oC using flue gas for heating. The flue gas is passed in the shell side of the shell and tube reactor. The condensed isopropanol and acetone are sent for fractionation.

One important property for which it is used as laboratory solvent is because does not form an azeotrope with water. Acetone is also used in various medical and cosmetic applications. It also forms an important component in food additives and food packaging.

Is pure isopropanol required as feedstock in the reactor? Therefore, if the azeotrope itself can be used as feedstock, then one can save azeotropic column costs if an acetone plant is constructed next to the isopropanol. Yes, isopropanol azeotrope can be used as a feed stock. In this case, the water will not react and will condense in the condenser after the reactor. Ans: The condenser removes the condensable components from the product vapors.

If condenser is not used, then the hot vapors move to the absorber and absorber load and degree of separation should be pretty high and hence higher cost. Apply lechartlier principle and suggest what pressures be operated in the reactor. Eventually comment on the existing pressures? Ans: If we apply Lechartlier principle, dehydrogenation reaction is favoured by lower pressures.

However, higher pressures are used in this case. If the pressure of the system does not play a critical role in the conversion, then higher pressures are favoured as they reduce the size of the reactor significantly for the throughput available.

Also, higher pressures are favourable for absorption and reduce the water load in the absorption column. Why is water from the isopropanol fractionators cooled and sent to the water absorber unit? Ans: This is due to the fact that absorption is favoured at lower temperature and higher pressure.

Why is isopropanol again sent to the compressor along with the feed? Ans: The operating pressures of the absorber, acetone fractionator and isopropanol fractionators reduce sequentially as the stream progresses to the right side. Therefore, the last column produces the product with about atmospheric pressure only. Therefore, to bring it back to 5 atm as in the reactor conditions, the stream has to be compressed along with the feed stream. In that way it controls the reaction temperature.

The benzene stream is recycled to enter the compressor. What alternative reactor arrangement is possible if pure propylene feed is used? Ans: When pure propylene is used, then there is no propane for quenching. Therefore, the packed bed reactor shall be provided a cooling jacket which can control the temperature of the reactor. Comment on the sequence of distillation columns separating propane, benzene and cumene in series?

Ans: The distillation columns are so arranged so that lighter components are separated first followed by heavier components. Since no component is present which will decompose on long time heating, this arrangement is followed.

If not, the component which can decompose upon long time heating will be separated first following by the lighter to heavier component sequence in the remaining components. In what way propane quenching plays a role in the reactions? Ans: Propane quenching reduces polymerization of cumene and formation of polyalkyl benzenes. How can one suppress polyalkylbenzene formation?

Ans: By using high feed ratio of benzene to propylene and using propane as a diluent 5. Is further heat integration not possible? Ans: A further heat integration can be carried out using hot vapors in the distillation column to be as hot streams in the reboilers of various distillation columns. In what way higher pressure in the product vapors from the reactor are beneficial for the deprpopanizer unit?

Ans: The depropanizer unit requires condensation of propane vapors in the condenser. Therefore, higher pressures to the extent of 25 atms will enhance propane boiling point to about 25 — 30oC for which cooling water can be used as the cooling media in the condenser.

If not, refrigerant needs to be used and the refrigerant will require a refrigerating unit along with the process. This is much much expensive than using cooling water as the cooling media. The reactor is maintained at — oC. The contact time for fluidization is in the order of seconds. The products absorbed in the water include acrylonitrile, acetonitrile and other heavy ends.

The azeotropic distillation column vapour is partially condensed to obtain a vapour, aqueous and organic layer. The vapour consists of Light ends and HCN and is let out. The organic layer consists of acrylonitrile and heavy ends is sent for further purification. The aqueous layer is sent as a reflux to the azeotropic column. In other words, addition of water enabled the formation of a heterogenousazeotropic mixture at the top.

The total condenser in this column generates both aqueous and organic layers. The organic layer is rich in acetonitrile and heavy ends where as the aqueous layer is sent back as a reflux to the azeotropic column. Why is oxalic acid added in the acrylonitrile purification column? Ans: One of the byproducts of the ammonoxidation of propylene are cyanohydrins. These organic compounds readily dissociate to form volatile compounds.

These volatile compounds are severely polluting compounds. Therefore, to avoid this, oxalic acid is added to the purification column in order to form complex compounds with these cyanohydrins and these compounds eventually enter the heavy end products. A careful analysis of the process flowsheet shown indicates that while absorption is favoured at lower temperatures and higher pressures, exactly opposite conditions exist for the reactor outlet stream at about 1 atm pressure and — oC.

What additional process modifications are suggested? Ans: Cooling the vapour product stream from oC to about 50oC in a series of heat exchangers. Since vapour is involved, extended area exchangers will be beneficial. Heat integration with the reboilers of any of the distillation columns is also beneficial. Pressurizing the vapour pressure to higher pressure and allowing it to enter the scrubber at the same temperature.

This is beneficial but compressor costs will be enormous. Therefore, in the light of the process costs, cooling the vapour stream is beneficial than compression to favour good absorption. In certain processes for acrylonitrile production, cyanohydrins removal is desired. If so, what process modifications are suggested? Ans: Cyanohydrins are in the bottom product obtained in the product splitter. Therefore, the bottom product can be sent to a reactor where cyanohydrins can be converted to acrolein and these acroleins can be separated and sent back to the ammonoxidation reactor fluidized beds.

In that case, oxalic acids are not used and the heavy ends will not also get produced significantly and therefore process topology will be somewhat different from what is being shown here. Is a partial condenser required in the acetonitrile azeotropic column? Ans: No, the reason is that the bottom product from the product splitter consists of heavy ends, acetonitrile and water and does not consist of lighter ends and HCN. Therefore, a partial condenser is not required and a total condenser producing two separate liquid phase streams that separate upon gravity is required.

A feed stock heater is not shown in the process. However, reactor operating conditions are indicate high temperature operation. How is the feed stock heated?

Ans: The heat for achieving the feed to desired temperature is provided by superheated steam that is mixed along with the feedstock.

Typical feed molar composition is propylene 7, ammonia 8, steam 20 and air Additional heat for the reaction is obtained from the highly exothermic reaction in the fluidized bed catalytic reactor. What are the advantages of the fluidized catalytic reactor when compared to a packed bed reactor? Ans: It is well known that the heat and mass transfer coefficients of gases are predominantly lower than those of the liquids.

Therefore, fluidization principle effectively enhances bulk phase mass and heat transfer coefficients of the gas solid catalytic reaction. In other words, due to fluidization, less contact time that is required in the process, higher conversions can be achieved.

The aldehydes can be subsequently subjected to hydrolysis to obtain short as well as long chain alcohols. These are o Dimerization of propylene to obtain 2-methylpentene o Isomerization of 2-methylpentene to obtain 2-methylpentene o Pyrolysis of 2-methylpentene to obtain isoprene along with methane as a side — product.

At these conditions, the mixture is in the liquid phase. From the flash tower a vapour and liquid stream are produced. The bottom product consists of propylene and dimerized product i. The top propylene product is then recycled back to mix with the fresh propylene feed stock and enter the mixer unit.

The quenching then produces a gas liquid mixture which is sent to a phase separator unit. What solvent can be used in the quenching process? Ans: HBr can be readily absorbed into water. Therefore, water can be used as a solvent in the quenching process. There is a patent available where it says that acetone can be used to recover HBr. More details can be obtained of this patent by furthering the search on the patent data base using the internet.

In the process flow sheet given the HBr recovery is not shown. Do you think the flow sheet is correct. Suggest any modifications to the flow sheet? Ans: Yes, the flowsheet has an error in that sense. The flowsheet should give a section for HBr recovery where HBr is recovered in the quenched solvent and the fresh HBr gas is allowed to enter the pyrolysis furnace along with the steam.

The fresh solvent can be then sent to a cooler and sent to the quench tower and the existing recycle stream to the quenching tower will not be there. Instead, this stream will go to the stripper as a feed stream. Can we not do heat integration partially for the pyrolysis furnace with the vapour products?

Ans: HBr is very corrosive and therefore, if we go for heat integration using the vapour product, then the shelf life of the pyrolysis furnace will be minimized. Ans: Yes, and this is not shown in the process flow sheet. Some impurities such as some light ends that might dissolve with the solvent will have to be purged, if not these can cause coking problems and can cause unwanted organics in the pyrolysis furnace reactor.

What sort of regeneration would you recommend for the isomerisation catalyst? Ans: Heating the catalyst in oxygen or air to remove coke would be beneficial to regain the activity of the isomerisation catalytic bed. Suggest what changes will be there in the process flow sheet if pure propylene instead of a mixture of propylene, propane and C1-C2 components is used? Ans: The C1-C2 tower and C3 towers can be replaced with a single tower after flash unit.

This new unit will separate all light ends in trace amounts in a single tower with middle product being 2-methylpentene and heavy ends as bottom product. Therefore, a complex distillation unit arrangement would be at the maximum required replacing three distillation columns in series. In that case, two molecules of aldehydes react to obtain a higher order aldehyde.

Various applications of these compounds include plasticizers for polymerization reactions, solvents, detergent raw materials etc. To do so, cold liquid stream obtained after phase separation is recycled.

The phase separator separates the unreacted synthesis gas by considering the propylene in the feed stock to be limiting and the liquid product stream. The liquid product stream is partially recycled back to the reactor to serve as a diluent to control the temperatures in the packed bed reactor. The flow sheet presented corresponds to production of butanol from propylene. If higher order alcohols are desired, how does the flow sheet get modified?

In such case, the cold liquid stream from the phase separator enters the dimerization reactor to convert lower order aldehydes to higher order aldehydes.

Suppose we wish to produce both short chain and long chain aldehydes and do not wish to produce alcohols then how does the process topology change? Ans: When both short and long chain aldehydes are required, then we have to allow the cold liquid from the phase separator to enter the dimerization reactor partially only.

Then the dimerization reactor product as well as the phase separator stream enter the decatalization unit to achieve catalyst recovery. Can the hydroformylation reactor be used as a dimerization reactor as well? Ans: Yes, in this way, we can produce all desired products in a single reactor and we can avoid dimerization reactor. But the balance between cobalt and zinc catalysts will dictate the product composition palette. Why high pressure is required in the hydroformylation reactor?

Ans: Higher pressures enable the formation of a complex between Cobalt and the hydrocarbons participating in the reaction. If higher pressure is not existent, the cobalt complex can decompose and this does not favour higher conversions. Can the series of distillation columns in the separator network be replaced with a complex distillation column? Ans: Yes, this is possible and this is recommended as the light end and heavy end products are not significant in make and the aldehyde products are the actual products that are desired.

A complex distillation reduces the number of columns required, enables complex interaction between both vapour and liquid streams and facilitates drastic reduction in the cost. Therefore, catalyst regeneration needs to be carried out very frequently. The product withdraw and stoppage of the feed flow to the reactor unit is carried out using valves. Air pre- heating is done using steam in an extended area heat exchanger equipment. Therefore during regeneration, another set of valves operate to allow the pre- heated air in and enable the product withdrawal after the combustion.

The hydrocarbon mixture consists of unreacted feed stock and butadiene and some heavy ends. The separation of n-butane, other hydrocarbons with butadiene is one of the difficult separations and they cannot be separated using ordinary distillation.

Therefore, a complicated route of separation is followed next that involves azeotropic distillation using ammonia. This solution is generated by absorbing ammonia into fresh cuprous ammonium acetate solution.