Interview Questions.

Question 1. What Are Some Common Causes Of Gas Pipeline Vibration 20 Carbon Steel Line?

Answer :

Check / keep in mind the subsequent:

 The higher strain range and /or the smaller pipe diameters activates me to investigate the opportunity that the fuel is attaining crucial glide somewhere downstream inside the pipe. When a gas gets to essential flow, sonic booms (generating vibration) are predicted. In reality, one of the primary approach with the aid of which the extra stress within the pipe is misplaced.
 If the source is a compressor, search for surging.
If the source is a tower, search for stress biking within the tower
 Look at critical flow via any manage valve that may be in the line.
Question 2. While There, Are Many Tests Available To Detect Leaks On Vessels, Is There A Technology Available To Quantify The Leak, Or Measure The Flow Through A Leak?

Answer :

The RheoVac air in-leak screen by Intek, Inc. In Westerville, OH is a viable meter that offers the real air in-leakage glide charge. It also gives you exhauster capacity and a vacuum satisfactory analyzing. 

Chemical Interview Questions
Question 3. Is There Any Way To Repair A Valve That Is Passing Leaking Internally Without Taking Our Process Offline?

Answer :

A 600 psig, 3" steam line is experiencing "passing" or inner leakage. If you order to update the valve, the system might must be taken offline. A brief technique to the problem is sought to get the plant to their subsequent scheduled shut down ANSWER Research on-flow leak sealing offerings. This problem is quite common. What they could do in this case is drill a hollow into the pass valve at the upstream side but not absolutely into the road. They could then faucet the hollow and install one among your injection fittings, which is like a small plug valve. They might then take a protracted 1/8" drill bit and drill thru the open injection becoming and into the pressurized line.

The drill bit is then eliminated and our injection gadget is then connected. Sealant (heavy fibers and grease) is pumped into the road and caught in the flow, so one can bind up in opposition to the leaking seat on the skip valve. If finished properly, this technique may be both powerful and secure.

Question 4. When Using A Pumping Loop To Mix Two Miscible Fluids In A Tank, When Can The Content Are Considered Well Mixed?

Answer :

A rule of thumb is to show the tank over three (three) times after which pattern the tank for mixture properties. By "flip the tank over”, we mean to force the entire quantity of the tank via the pump as a minimum 3 instances. More turnovers can be necessary, however 3 instances is a good place to begin.

Question 5. What Are Some Good Uses Of Low-grade Steam At 12 Atm And 1920c?

Answer :

There are numerous traditional methods to appoint waste steam in an running plant:

You can generate energy thru a steam turbine-generator set. The power is typically positioned returned in the line; that is the concept at the back of the "Co-Gen" concept used nowadays in lots of USA vegetation. Steam mills can efficiently use saturated steam deliver all the way down to 75 - 100 psig. In unique conditions, they have used down to 50 psig as a turbine steam deliver. I have used steam as little as a hundred psig.
You can pre-warmness system streams that require pre-heating; this is completed by applying warmness exchangers.
You can appoint the waste steam as a refrigeration source by means of employing it in vacuum jet ejectors and producing 50 of cooling water.
You need to keep in mind those as viable alternatives if you could pick out the heating, cooling and power conservation requirements. An financial analysis is needed to discover the most appealing alternative. You usually utilize a Discounted Cash Flow analysis to base your selection and that means you have to study each case as to financial savings generated. A fourth method is probably that you may use the steam for environmental heating (if you stay in a cold climate).

BioChemistry Interview Questions
Question 6. What Is A Good Way To Get Started In Doing A Plant-extensive Steam Consumption Analysis?

Answer :

It is doubtful as to whether or no longer you realize the whole steam consumption. If you do not, one manner to get it's far to take the nominal capacity of the boiler in terms of heat, i.E. The entire rated Btu/hr. This is typically available both via the documentation you have got for the boiler or maybe on the nameplate. You also must understand the steam stress you're producing. Using the steam tables, get the enthalpy of the steam and divide it into the nominal boiler capability to get the whole price. I wish which you also recognize how plenty of the capability you are the use of, 50%, seventy five% and so forth. Multiply this via the entire lb/hr to get your fee.

Another way to get the ability is through using the quantity of boiler feed water you're sending to the boiler and the acknowledged degree of steam you are generating. Do not neglect to consist of the blow down to your warmness & mass stability. Getting the price to every plant is greater hard if you are missing in instrumentation. Use as tons plant instrumentation as possible; glide meters, stress and temperature indicators. If you do now not have a meter in every header to every plant, then see if you have them in sections or to pieces of equipment using the steam. Another manner is to degree the quantity of condensate you are returning to the boiler. If you are dumping the condensate, you will be capable of accumulate and measure the amount in a pail from every supply. Another manner is to use the system.

Question 7. Are There Any General Rules For Flushing Slurry Lines?

Answer :

Slurry strains must be flushed with a minimum fluid speed of 10 toes/s and the overall flushing liquid quantity have to same three-6 times the total piping volume.

Analytical Chemistry Interview Questions
Question 8. What Is Pneumatic Conveying?

Answer :

Pneumatic conveying is a technique of transferring bulk solids from one region to every other with the assist of a service fuel. A differential pressure is implemented internal a conveying line. The waft constantly movements from a vicinity of better to decrease strain.

Question nine. What Types Of Pneumatic Conveying Systems Are Typically Used?

Answer :

Essentially, there are  sorts of pneumatic conveying structures. In dilute section structures, the solids are suspended within the provider gasoline and transported to their destination. In dense section systems, the solids-to-gas ratio is plenty higher. The gas in these structures acts greater like a piston to push the product to its final vacation spot. Dilute phase systems are extra normal than dense phase structures due to the fact they are able to appoint high quality pressure displacement or a vaccum gadget. Dense segment conveying is beneficial if the product degrades effortlessly (works at decrease velocities) or is especially abrasive.

Quality Control Chemist Interview Questions
Question 10. What Is The Most Common Carrier Gas Used In Pneumatic Conveying?

Answer :

While many packages utilize air as a provider gasoline, others aren't appropriate for using air. For example, if the substance being conveyed reactions with moisture within the air or if there may be a hazard of dust explosions, nitrogen is in all likelihood desire.

Question 11. What Are Some Common Problems Associated With Dense Phase Pneumatic Conveying?

Answer :

Dense section pneumatic conveying, typically experiences one common trouble from gadget to gadget: plugging inside the line because of a malfunctioning booster valve. Dense segment systems require these booster structures to introduce new, pressurized air. These boosters are almost always followed through a check valve. If the check valve becomes stuck, the product is allowed to plug the road.

Organic Chemistry Interview Questions
Question 12. What Are Some Common Problems Associated With Dilute Phase Pneumatic Conveying?

Answer :

Probably the maximum common problem encountered in dilute phase pneumatic conveying is the sporting of the rotary valve that serves as an air lock in which the product is delivered into the machine. If excess air is authorized to bypass by means of the rotary valve, this will cause bridging of the cloth the glide may be slowed or stopped.

Chemical Interview Questions
Question 13. What Is Some Common Piping Materials Used To Transport Slurries?

Answer :

When deciding on a piping fabric to transport slurries, corrosion and erosion considerations should be accounted for.

Some of the most popular piping materials include:

 Carbon Steel
 Stainless Steel
 High Density Polyethylene (HDPE)
 Acrylonitrile butadiene stryene (ABS)
 Unplasticized polyvinyl chloride (uPVC)
 Fiberglass reinforced plastic (FRP)
 Elastomer-coated carbon steel
Question 14. How Can You Prevent Bridging In A Dilute Phase Pneumatic Conveying System?

Answer :

Manufacturers of these systems advise bin agitation or blowing air into the pinnacle of the feeding bin. These methods can save you first-rate particle from bridging near the rotators valve. Two types of particles which can be in particular at risk of bridging encompass titanium dioxide and calcined- kaolin clay.

Question 15. What Is The Best Way To Handle Bend Or Turns In Slurry Piping Systems?

Answer :

Even long radius elbows need to be averted in slurry pipes and features. They are often the site of intense erosion or solid/liquid separation. Only gentle pipe bends or sweeps need to be used to show a slurry line. Industrial enjoy has proven that a bend-radius-to-pipe-diameter ratio of 3-five is usually recommended.

Polymer Chemistry Interview Questions
Question sixteen. How Can You Determine The Proper Pipe Thickness For A Slurry Line?

Answer :

Design of slurry piping systems must comply with ANSI/ASME B31.1 and B31.11 Codes. A simple equation for this calculation is as follows: t = (PD) / (2S) + C in which: t = pipe wall thickness, in. P = most design strain of the pipe, psig S = maximum allowable design stress, psig C = corrosion or erosion allowance, in.

Question 17. What Is The Practical Particle Size Limit For Pneumatic Conveying?

Answer :

As a rule, pneumatic conveying will paintings for particles up to two inches in diameter with a standard density. By "usual density”, we mean that a 2 inch particle of a polymer resin may be moved through pneumatic conveying, however a 2 inch lead ball might now not.

Oil and Gas Interview Questions
Question 18. What Can Cause Bulk Solids To Stop Flowing From A Bin?

Answer :

Causes of such issues can fall into considered one of two categories: Material power or Bin Geometry: Factors which could have an effect on cloth strength encompass. Moisture is specifically with debris, which fuse collectively with moisture.

BioChemistry Interview Questions
Question 19. What Is The Most Common Cause Of Solid Size Segregation In Bulk Solid Systems?

Answer :

Many engineers usually point without delay to the pneumatic conveying machine as a supply of such a hassle. The truth is that during maximum cases, segregation happens because of the differences in sizes of the articles. As a rule-of-thumb, if the dimensions ratio extends out of doors of round 1:1.3, then there'll maximum likely be segregation. This being said, one must check out the system chargeable for determining the particle length in preference to the pneumatic conveying device if this trouble is going on. Reference: Richard Farnish, the Wolfson Centre for Bulk Solids Handling Technology

Question 20. How Can One Determine The Particle Size Distribution For A Given Bulk Solid?

Answer :

While there are excessive-tech techniques of appearing such an evaluation (laser-diffraction and video imaging system are to be had), the handiest manner is to apply a sieve stack. For example, to analyze a selected stable, one would stack several extraordinary mesh sizes right into a cylinder with the largest mesh establishing on the top and progress down through the cylinder to finer mesh. The cylinder might include a pan on the lowest. Before beginning, weight the check sample, every piece of mesh, and the pan. Then, the sample is loaded into the pinnacle of the take a look at cylinder and the cylinder is exposed to a mixture of actions (shaken) to permit the solids to skip thru the best mesh sizes.

Geochemistry Interview Questions
Question 21. What Is A "saltation Velocity" And How Is It Used In Designing Pneumatic Conveying Systems?

Answer :

The saltation pace is defined as the real gas velocity (in a horizontal pipe run) at which the particles of a homogeneous strong waft will start to fall out of the fuel circulate.

In designing, the saltation pace is used as a foundation for deciding on the layout fuel pace in a pneumatic conveying gadget. Usually, the saltation gas speed is expanded by a element, that is dependent on the nature of the solids, to reach at a design gas pace.
For instance, the saltation velocity thing for quality particles may be about 2.Five while the component may be as excessive as five for direction particles inclusive of soybeans could.

Question 22. What Are Some Characteristics Of Bulk Solids That Can Affect Their Ability To Flow Properly?

Answer :

Four (four) main elements to recollect include moisture content material, temperature, particle size (and shape), and time at relaxation.

An increase in moisture content will usually make solids extra "sticky". Some solids will absorb moisture from the air, which is why nitrogen is regularly used as a provider fuel (among other reasons).
For a few solids, their potential to go with the flow may be adversely impacted with the aid of temperature or even the period of time that the debris are exposed to a selected temperature. For instance, soybean meal flows nicely at ninety °F but begin to form massive bridges at a hundred °F.
Generally, the finer a bulk strong turns into, the more cohesive the debris. Round particles are commonly less difficult to handle than "stringy" or oddly formed debris. As particles rest in a bin, they can compact together from their personal weight. This can create strong bonds among the debris.
Often instances, re-starting up drift can destroy these bonds and the solids will go with the flow as ordinary, but this will depend upon the weight at given places inside the bin.
Question 23. What Is A Good Method Of Steam Tracing Large Vessels?

Answer :

One common method to warmness tracing tasks is a "platecoil" concept. If you're unfamiliar with this kind of equipment, you must go to one of the hyperlinks underneath. Depending to your tank(s) or application, the platecoil can effortlessly steam trace (or heat-up) your manner. The technique of software is easy and automatically completed by means of sub-contractors. New heat-tracing cements have made this method even extra green and much less high-priced than what we had in the beyond. The platecoils can be pre-fashioned to suit your tank's cylindrical shell or elliptical heads. Flat surfaces are very clean.

Platecoils are a brief, low-price, and safe installation. Most platecoils are observed in stock, off-the-shelf in stainless construction. I even have used them to winterize tanks in addition to to lessen viscosities in heavy polyols and other high molecular weight compounds even as processing or all through garage. One of the quality functions of this sort of tracing is that it isn't always invasive -- depending on the application, you will be able to set up the platecoils whilst the tank is working. Still any other interesting feature is that you could use them as an meeting internal of tanks --- as internal heaters. You can use steam, Dowtherm, warm oil or method streams within the coils. You can easily insulate over them to preserve warmth or to guard personnel. Another aid could be a guide via Spirax Sarco (link below). This ebook includes loads of data on steam tracing, high-quality practices, traps, regulating valves.

Chemistry Interview Questions
Question 24. Is It Advisable To Cool A Fin Fan By Spraying Demineralized Water On It?

Answer :

Fin fan has carbon steel tubes with aluminum fins RESPONSE In a similar service, the fin fan suffered outside corrosion while spraying it with demin water. The salt and oxygen within the air corrodes the air-cooler.

The gas is piped generally from an outside cylinder garage facility to a procedure control panel at about 60 psig. The panel-output chlorine strain is 15 psig and a go with the flow rate of about 0.03 scfm. Occasionally the drift manipulate gadgets in the system panel are contaminated by what appears to be liquid chlorine. It appears that temperature variations within the iron shipping pipe might also have a few influence at the liquid formation.

The condensation temperature of gaseous chlorine at 65 psig is 54 deg F. Thus, in case your transport line is lengthy, it's far pretty likely that ambient temperatures decrease than 54 deg F ought to bring about cooling the line enough to reason condensation of the chlorine fuel. If you lower the delivery pressure to twenty-five psig, the condensation temperature would be 24 deg F ..., which should significantly decrease the likelihood of bloodless ambient temperature inflicting the gas to condense.

Analytical Chemistry Interview Questions
Question 25. How Can You Control The Ph Level In Our Cooling Water With Respect To Ammonia Contamination?

Answer :

A cooling tower in a urea production facility is experiencing very high ammonia degrees (2 hundred to three hundred ppm) within the cooling water. The ammonia level fluctuates with wind course.

RESPONSE if your cooling water has 200-three hundred ppm of ammonia, you've got a trouble, which have to be solved. You may additionally have a water-cooled technique warmth exchanger, which has a tube leak this is leaking ammonia into your cooling water. Or the ambient air for your urea plant has a full-size ammonia content (from diverse fugitive leak sources consisting of piping flanges, manipulate valve packing glands, pump and compressor seals, and many others.) and while the wind blows that ambient air into the cooling tower, the ammonia is absorbed inside the cooling water. 

In both event, you have got an dangerous state of affairs, which need to be corrected. Contacting a organisation this is specialised in those varieties of water treatment issues can be a wise decision (Ex/ Nalco).

Question 26. How Can You Keep Our Seawater Used For Heat Rejection Clean Before Entering Our Heat Exchangers?

Answer :

Seawater is used as a cooling agent in condensers and coolers. Intermittent injection of chlorine gas is used to cast off marine growth. The device is a as soon as via type. The band displays before the suction of the pumps are speculated to take away scales and different suspended materials. The band monitors are not nicely functioning. Cooling water go with the flow is ready 2.6 million gallons in line with hour.

The prescreening and cell displays are not a sufficient safety for the recirculating water. This is a totally not unusual problem. In easy salt water the organic grow in the cooling water pipes is the primary problem (mussels, barnacle, algae, and many others.). After the lifestyles cycle is finished they die and blocking the condenser tubes. To solve this particles problems use self-cleansing Debris Filters (DF) without delay mounted in the front of the waterbox of the warmth exchangers.

Chemical response Interview Questions
Question 27. We Have Some Pieces Of Metals That Have Been "powder Coated", How Does That Work?

Answer :

Powder coatings are similar to paint, but they are usually a good deal extra durable. Rather than including a solvent to the pigments and resins in paint, as is commonly the case, powder coatings are carried out to the surface in a first-class granular shape. They are generally sprayed on so they keep on with the surface. Once the surface has been sufficiently spray coated, the piece is baked at excessive temperatures, and the pigment and resins portions melt and shape a long lasting, shade layer.

Quality Control Chemist Interview Questions
Question 28. What Industries Require Filtered Compressed Air?

Answer :

Almost every chemical procedure, electricity plant food processing etc. Plant has some form of air-operated device... From manipulate valves to air operated pumps... And all have an air compressor delivering filtered air.

Question 29. What Are Some Good Tank Mixing Rules Of Thumb?

Answer :

For fluid with viscosities under 10,000 Cp, baffles are tremendously advocated. There ought to be four baffles, 90 stages aside. The baffles need to be 1/12th the tank diameter in width and ought to be spaced off the wall through 1/fifth the baffle width. The off- wall spacing allows to do away with dead zones. If baffles are used, the mixer should be established inside the vertical function inside the middle of the tank. If baffles are not used, the mixer must be mounted on an perspective, ~15 tiers to the proper and located off center. This breaks up the symmetry of the tank and simulates baffles although now not almost as excellent as baffles.

The reason of baffles is to prevent solid frame rotation all factors in the tank are transferring on the same angular pace and no top to bottom turnover. The formation of a big principal vortex is a feature of strong frame rotation. However, small vortices that journey around the fluid floor, disintegrate, and reform are extra a characteristic of the extent of agitation.

Petroleum Engineering Interview Questions
Question 30. What Is A Good Source Of Equations For Calculating Discharge Flowrates From Accidental Releases?

Answer :

If you're interested in the calculation of discharge drift fees from unintentional releases, read the online technical article "Source Terms for Accidental Discharge Flow" at the internet site beneath. It offers the equations used for a variety of not unusual types of unintentional gas or liquid releases and explains how to use them.

Question 31. What Is The Definition Of "exact" Cooling Tower Water?

Answer :

Generally speaking, cooling tower water should have a pH among 6 and 8, a chloride content no more than 750 ppm, a sulfate content material (SO4) underneath 1200 ppm, and a sodium bicarbonate (NaHCO3) content underneath two hundred ppm. Additionally, cooling tower water need to now not be heated beyond one hundred twenty °F to keep away from plating out of treatment chemical substances in technique coolers.

In addition, if loose chlorine is used for biological increase manage, it must be introduced intermittently with a loose residual now not to exceed 1 ppm and this should be maintained for short periods.

Question 32. When Specifying A Cooling Tower, Should I Look Up Historic Wet Bulb Temperatures For My Area Or Should I Take Measurements?

Answer :

If that is a brand new set up, appearance up ancient moist bulb temperatures for place and make sure to record them to the cooling tower producer as "ambient moist bulb temperatures". The manufacturer will regulate this temperature for that reason to estimate an "entering moist bulb temperature".

If you have got an present tower this is to be replaced, take several wet bulb temperature measurements near the air inlet in the course of the most up to date months. Report this as the "coming into moist bulb temperature" to the tower manufacturer.

The difference between the ambient and the getting into wet bulb temperatures is to account for wet recirculation from the tower exit returned to the tower front. The getting into wet bulb temperature continually better than the ambient wet bulb temperature.

Electrochemistry Corrosion Interview Questions
Question 33. Is There A Rule Of Thumb To Estimate The Footprint Of A Cooling Tower During Design Phase?

Answer :

Over the years, this one has regarded to face the check of time:
Every million Btu/h of tower capability would require about one thousand ft2 of cooling tower basin area.

Organic Chemistry Interview Questions
Question 34. What Could Be A Possible Cause For Sudden Foaming In A Cooling Tower?

Answer :

Assuming that no different modifications have been made, especially to the water treatment chemical compounds, the maximum commonplace outcome to this mystery is a leaking warmness exchanger.
Begin a scientific check of all the heat exchangers that use the cooling tower water and look into them very well for leaks. Even small amounts of a few chemicals can cause huge foaming issues inside the tower. In addition, now not all of these additives will set off a conductivity alarm.

Question 35. What Factors Should Be Compared When Evaluating Cooling Tower Bids?

Answer :

Examining the subsequent factors have to allow for an inexpensive assessment of cooling towers:

Purchased price
Installed value
Fan power intake
Pump energy intake
Water use
Water remedy fees
Expected protection charges
Worker safety necessities
Environmental protection
Expected provider existence
Question 36. For A Heat Exchanger, Will The Overall Heat Transfer Coefficient Increase Along With An Increase In Lmtd (log Mean Temperature Difference) Around The Unit?

Answer :

The normal warmth switch coefficient is usually weakly dependent on temperature. As the temperatures of the fluids trade, the degree to which the general heat transfer coefficient will be affected depends on the sensitivity of the fluid's viscosity to temperature. If each fluids are water, for example, the overall warmth transfer coefficient will no longer vary a lot with temperature because water's viscosity does now not trade dramatically with temperature. If, but, one of the fluids is oil which can also have a viscosity of one thousand cP at 50 °F and 5 cP at 400 °F, then indeed the overall heat transfer coefficient could be a great deal higher at better temperatures because the oil side might be proscribing.

Realize that the overall heat switch coefficient is dictated by the nearby warmness switch coefficients and the wall resistances of the warmth exchanger. The nearby heat switch coefficients are dictated by way of the fluid's physical houses and the speed of the fluid through the exchanger. So, for a given warmth exchanger, fluid drift rates, and characteristics of every fluid....The region of the exchanger and the overall heat transfer coefficients are fixed (theoretically besides....As the overall warmness transfer coefficient does vary slightly along the length of the exchanger with temperature as I've mentioned and the U-fee will lower over the years with fouling).

Polymer Chemistry Interview Questions
Question 37. What Is Condensate Lift?

Answer :

This is a time period that is usually used to suggest how a whole lot pressure is required to 'lift' condensate from a steam lure or different tool to it is destination at a condensate go back line or condensate vessel. The first photograph underneath shows a state of affairs wherein a properly sized manipulate valve is used on a steam heater. During nominal operation, the utility steam undergoes a nominal 10-25 psi strain loss through the valve. For typical software steam (150 psi or better), this can go away a stress on the steam trap exit this is regularly adequate to raise the condensate to its vacation spot. For example, if the steam losses 20 psi via the valve and another 15 psi via the heater and piping, that can depart up to 265 feet of head to push the condensate to the header. In this example, there may be little want for a condensate pump.

On the opposite hand, if the control is simply too huge, it's going to only be some percent open for the duration of normal operation and the steam can go through a stress loss of 50-75 psi or even better! In addition to imparting terrible control for the heater, it additionally reduces the available head for condensate raise. In this example, or if the steam deliver pressure is rather low, it is able to be necessary observe the steam entice with a separation vessel and a condensate pump to push the condensate to the go back line.

Question 38. What Type Of Heat Exchangers Are Most Commonly Used For A Large-scale Plant-cooling Loop Using Seawater As The Utility?

Answer :

Commonly referred to as a "secondary cooling loop" or SECOOL, a closed loop water system is circulated thru a processing plant close to a sea. Process warmth is transferred into the closed loop water and then this water is circulated through warmth exchangers to transfer (reject) the warmth to seawater. This is a hallmark plate and frame heat exchanger utility.

The higher warmness transfer coefficients which can be to be had in plate and frames exchangers (PHEs) will minimize the hooked up value because the cloth of production of preference it Grade 1 Titanium (better U-cost manner decrease location). To fight pluggage the slender passages in the exchangers, the seawater is typically run thru huge automatic backflush strainers designed in particular for seawater. Periodically, those strainers will opposite glide and "blowdown" particles to clean the strainer. This technique has been used for many years with first rate fulfillment.

Question 39. Can Condensate Control In A Reboiler Cause Water Hammer Problems?

Answer :

 It could be very commonplace to manipulate reboilers on distillation columns via this approach. This is not to mention that this manage approach is the high-quality for any heat exchanger the use of steam for heating. For instance, if there is an appreciable degree of subcooling of the condensate, the incoming steam can revel in "fall apart" (or thermal water hammer) whilst it's far exposed to the cool condensate. In reboilers, the manner fluid is sincerely being vaporized so little or no subcooling of the condensate takes location.

This makes for a good opportunity for condensate level manage in a vertically oriented shell and tube reboiler. The degree controller is commonly located on a vessel this is installed at the side of the shell side of the reboiler. This will allow for complete condensate drainage (if vital) and there's no need to weld at the shell of the exchanger

Question 40. Why Is A Vacuum Breaker Used On Shell And Tube Heat Exchangers That Are Utilizing Steam As The Heating Utility?

Answer :

Vacuum breakers are regularly hooked up at the shell aspect (steam aspect) of shell and tube exchangers to allow air to enter the shell in case of vacuum conditions developing in the shell. For an exchanger including this, the shell aspect ought to already be rated for full vacuum so the vacuum breaker is not a stress (vacuum) remedy tool. Development of vacuum inside the shell should permit condensate to construct within the unit and water hammer may additionally result.

Oil and Gas Interview Questions
Question forty one. What Is A Barometric Condenser?

Answer :

Single-level or multi-degree steam-jet-ejectors are frequently used to create a vacuum in a system vessel. The exhaust from such ejector systems will contain steam (and possibly different condensable vapors) as well as non-condensable vapors. Such exhaust streams can be routed right into a "barometric condenser" that is a vertical vessel where the exhaust streams are cooled and condensed via direct touch with downward flowing cold water injected into the pinnacle of the vessel.

The vessel is hooked up in order that its bottom is at least 34 ft (10.Four meters) above the ground, and the effluent cooling water and condensed vapors waft thru a 34-foot period of vertical pipe referred to as a "barometric leg" into small tank referred to as a "hotwell". The "barometric leg" lets in the effluent coolant and condensed vapors to exit regardless of what the vacuum is in the technique vessel. Such a gadget is referred to as a "barometric condenser". The non-condensable vapors are withdrawn from the top of the condenser through using a vacuum pump or possibly a small steam ejector. The effluent coolant and condensed vapors are removed from the hotwell with a pump.

Question 42. What Is The Best Way To Control An Oversized, Horizontally Oriented Shell And Tube Steam Heater?

Answer :

A used shell and tube warmth exchanger is for use in steam heating duty. The warmness exchanger is larger than vital and the manipulate scheme to be hired is being investigated. The steam to be used may be 65 psia-saturated steams. The process fluid is a liquid brine fluid.

 The real stress in the heater, whilst the steam is condensing is dependent on the condensing fee and the general dirty U. Tubes can be plugged to lessen the quantity of warmth transfer area, so long as the manner facet (tube) velocity does no longer get too high. Calculate the wanted area and then the required steam glide rate. An orifice can be sized to govern the steam waft fee; however, at decreased loads the condenser may also enjoy partial vacuum conditions so ensure that the shell is rated for full vacuum. When this partial vacuum situation does arise, choked glide will be skilled via the steam control valve. The Cv trim value could want to be sized such that the choked flow does not exceed what is wanted. This is tricky and calls for numerous trim size alternate outs.

Geochemistry Interview Questions
Question forty three. Is It Ever Advantageous To Use Shells In Series Even Though It May Not Be Necessary?

Answer :

Usually you layout for the least variety of shells for an item. However, there are instances while it is greater good value to add a shell in series to the minimum configuration. This can be while there may be a quite low drift in the shell facet and the shell move has the bottom warmness transfer coefficient. This happens when the baffle spacing is close to the minimum. The minimal for TEMA is (Shell I.D. /5). Then adding a shell in collection gives a higher speed and heat transfer because of the smaller flow region inside the smaller exchangers which are required.

Question 44. What Is Some Good Advice For Specifying Allowable Pressure Drops In Shell And Tube Exchangers For Heavy Hydrocarbons?

Answer :

Frequently method engineers specify 5 or 10 PSI for allowable pressure drop inner heat exchanger tubing. For heavy beverages which have fouling characteristics, that is normally not enough. There are cases where the fouling excludes the use of tabulators and using greater than the normal tube stress drop is fee powerful. This is specifically real if there is a fantastically better warmth switch coefficient on the outdoor of the tubing. The following example illustrates how Allowable stress drop could have a big impact at the surface calculation. A propane chiller changed into cooling a fuel treating liquid that had an average viscosity Of 7.5 cP.

The effect at the calculated surface become as follows: Allowable tube stress drop Exchanger surface five PSI 4012 Sq. Ft. 25 PSI 2104 Sq. Ft. 50 PSI 1419 Sq. Ft. You can see that the usage of 25-PSI pressure drop decreased the surface by way of almost one-1/2. This would bring about a rate reduction for the heat exchanger of approximately 40%. This financial savings offset the value of the pumping power.

Question 45. What Is A Good Approximation For The Heat Transfer Coefficient Of Hydrocarbons Inside three/four" Tubes?

Answer :

Use the following equation to estimate the warmth transfer coefficient while liquid is flowing internal 3/four inch tubing: Hio = one hundred fifty./sqrt(avg. Viscosity) Where: Hio (BTU/ft2-hr-0F Viscosity (cP) that is constrained to a maximum viscosity of 3 cP.

Question 46. What Is A Good Relation To Use For Calculating Tube Bundle Diameters?

Answer :

The following are equations for one tube pass bundle diameter whilst the tube rely is understood or preferred: 30 Deg. DS = 1.052 x pitch x SQRT(matter) + tube O.D. Ninety Deg. DS = 1.Thirteen x pitch x SQRT(be counted) + tube O.D. Where: Count = Number of tubes DS = Bundle diameter in inches Pitch = Tube spacing in inches

Question 47. What Effect Does Choking A Vertical Thermosiphon Have On The Heat Transfer Rate?

Answer :

Choking down on the channel outlet nozzle and piping reduces the move price thru a warmth exchanger. Since the tubeside heat-switch price depends on pace, the heat transfer is decrease at reduced recirculation fees. A rule of thumb says that the internal go with the flow region of the channel outlet nozzle and piping need to be the same as the glide area inside the tubing. Shell Oil in an experimental examine confirmed that a ratio of 0.7 in nozzle flow region/tube waft vicinity reduced the warmth flux through 10%. A ratio of 0.4 cut the heat flux nearly in half of.

Question forty eight. How Can One Quickly Estimate The Additional Pressure Drop To Be Introduced With More Tube Passes?

Answer :

When the calculated stress drop within the tubes is underutilized, the envisioned pressure drop with accelerated quantity of tube passes is new tube DP = DP x (NPASS/OPASS)3 Where NPASS = New wide variety of tube passes. OPASS = Old variety of tube passes this will be an amazing estimate if gain isn't taken of the increase in warmness transfer. Since the increased number of tube passes gives a higher pace and increases the calculated warmth switch coefficient, the wide variety of tubes for use will lower. Fewer tubes boom the brand new stress drop. For a better estimate of the brand new strain drop, add 25% if the warmth transfer is all sensible warmth. Source: Gulley Computer Associates

Question forty nine. Can Large Temperature Differences In Vaporizers Cause Operational Problems?

Answer :

Large temperature variations in warmth exchangers where liquid is vaporized are a caution flag. When the temperature differences attain a sure fee, the cooler liquid can not reach the heating floor because of a vapor film. This is known as movie boiling. In this circumstance, the heat transfer deteriorates due to the lower thermal conductivity of the vapor. If a layout evaluation suggests that the temperature distinction is close to causing film boiling, the vaporizer should be began with the boiling aspect complete of pretty cooler liquid.

This manner, you do not begin flashing the liquid. The liquid is slowly heated up to a extra strong condition. If the vaporizer is steam heated, the steam stress should be reduced as a way to reduce the temperature difference. With steam heating, take a close examine the layout if the MTD is over 90 0F that is close to the crucial temperature difference in which film boiling will begin.

Question 50. When Should One Be Concerned With The Tube Wall Temperature On The Cooling Waterside Of A Shell And Tube Exchanger?

Answer :

When designing heat exchangers wherein hot technique streams are cooled with cooling water, test the tube wall temperature. Hewitt says that wherein calcium carbonate may also deposit heat, switch surface temperatures above 140 0F ought to be prevented. Corrosion effects should also be taken into consideration at hot tube wall temperatures. As a difficult rule of thumb, make this test if the inlet manner temperature is above 2 hundred 0F for mild hydrocarbon beverages and 300-400 0F for heavy hydrocarbons. Consider using Aircoolers to convey the process fluid temperature down earlier than it enters the water-cooled exchanger.

Question 51. When An Expansion Is Joint Needed On The Shell Side Of A Shell And Tube Heat Exchanger?

Answer :

A fixed tube sheet exchanger does now not have provision for enlargement of the tubing whilst there is a distinction in metal temperature between the shell and tubing. When this temperature difference reaches a sure point, a spread joint within the shell is needed to relieve the pressure. It takes a miles decrease metal temperature difference when the tube steel temperature is hotter than the shell steel temperature to require a selection joint. Typically, an all metal exchanger can take a maximum of about 40-0F steel temperature difference while the tube side is the hottest. When the shell side is the freshest, the most is normally 150 0F. Usually if a diffusion joint is required, it is due to the fact the maximum allowable tube Compressive strain has been surpassed. According to the TEMA manner for comparing this pressure, the compressive strain is a strong characteristic of the unsupported tube span.

Question 52. What Kind Of Concerns Is Associated With Temperature Pinch Points In Condensers?

Answer :

Be extra careful when condensers are designed with a small pinch factor. A pinch factor is the smallest temperature distinction on a temperature vs warmth content plot that indicates each streams. If the actual pressure is less than the process design running stress, there can be a tremendous loss of heat transfer. This is mainly authentic of fluids that have a relative flat vapor pressure plot like ammonia or propane. For instance: If an ammonia condenser is designed for 247 PSIA operating stress and the real strain is 5 PSI less and the pinch point is eight 0F, there can be a sixteen% drop in heat switch.

Question fifty three. What Factors Go Into Designing The Vapor Space Of Kettle Type Reboiler?

Answer :

The length of the kettle is decided with the aid of several factors. One component is to offer sufficient area to gradual the vapor velocity down enough for nearly all the liquid droplets to fall go into reverse by way of gravity to the boiling surface. The quantity of entrainment separation to layout for depends on the character of the vapor destination. A distillation tower with a massive disengaging area, low tower efficiency, and high reflux rate does now not require as plenty kettle vapor space as ordinary.

Normally the vapor outlet is focused over the bundle. Then the vapor comes from two one-of-a-kind directions as it approaches the opening nozzle. Only in uncommon cases are those two vapor streams identical in quantity. A simplification that has been significantly used is to anticipate the best vapor waft is 60% of the whole. In one case, where this would purpose an undersized vapor space is while there is a much larger temperature difference at one stop of the kettle then the other. The minimal top of the vapor area is usually eight inches.

Question fifty four. Is There A Quick Rule-of-thumb To Estimate A Gas Side Heat-transfer Rate Inside The Tubes Of A Shell And Tube Heat Exchanger?

Answer :

If you need to estimate a gasoline warmness transfer price or see if a program is getting an affordable gas charge, use the following: h = 75 X Sq. Root(Op. Stress/one hundred) The operating pressure is expressed as absolute. This is for inside the tubes. The rate will be lower for the shell side or if there's more than one exchanger.

Question fifty five. Are There Any Alternatives To Scraping A Shell And Tube If A Capacity Increase Will Make The Pressure Drop Across The Exchanger Too Large?

Answer :

When an boom in capacity will cause excessive stress drop, you could not ought to junk the heat exchangers. A noticeably cheaper alteration is to reduce the range of tube passes. Other possibilities are arranging the exchangers in parallel or the use of lowfins or different unique tubing.

Question 56. What Is A Good Method Of Minimizing Shell Side Pressure Drop In A Shell And Tube Exchanger?

Answer :

When shell pressure drop is vital and impingement protection is needed, use rods or tube protectors in pinnacle rows in preference to a plate. These create much less pressure drop and better distribution than an impingement plate. An impengement plate causes an abrupt 90-degree flip of the shell circulation, which reasons more strain drop.

Question 57. What Are Some Good Strategies For Curing Tube Vibration In Shell And Tube Exchangers?

Answer :

Most glide-triggered vibration takes place with the tubes that bypass via the baffle window of the inlet zone. The unsupported lengths ultimately zones are usually longer than, those within the rest of the package. For 3/four inch tubes, the unsupported duration can be 4 to five toes. The remedy for detachable bundles, where the vibration is not extreme, is to stiffen the package. This may be performed by using placing steel slats or rods between the tubes. Normally this only wishes to be done with the primary few tube rows. Another answer is to add a shell nozzle opposite the inlet to reduce the inlet fluid velocity in half of. For non-detachable bundles, that is the satisfactory answer. Adding a distributor belt at the shell could be a very good solution if it had been no longer so steeply-priced.

Question fifty eight. What Are Some Of The Consequences Of An Undersized Kettle Type Reboiler?

Answer :

The impact might be a decrease within the boiling coefficient. A boiling coefficient relies upon on a nucleate boiling factor and a two-segment aspect that depends on the recirculation price. An undersized kettle will now not have enough space at the sides of the package for top recirculation. Another effect is high entrainment or even a -segment mixture going lower back to the tower.

Question 59. Are Some Heat Transfer Services More Prone To Tube Vibration That Others For A Shell And Tube Exchanger?

Answer :

Bundle vibration can purpose leaks because of tubes being reduce at the baffle holes or tubes being loosened at the tubesheet joint. There are services which can be more likely to reason package deal vibration than others are. The maximum probably carrier to motive vibration is a unmarried-phase fuel operating at a pressure of one hundred to three hundred PSI. This is specially proper if the baffle spacing is more than 18 inches and unmarried segmental.

Question 60. Is There A Difference In Mtd (suggest Temperature Difference) Between "e" And "j" (divided Flow) Type Shell And Tube Heat Exchangers?

Answer :

Divided glide (shell type J) does no longer have the same correction as the standard go with the flow sample (shell type E). Thermal layout application make this correction issue mistake. True, there may be very little difference at correction factors above zero.Ninety. However, there may be a distinction at decrease values. For example, Equal outlet temperatures Shell kind "E" correction Fn = 0.805 Shell type "J" correction Fn = 0.775 Cold outlet 5F better than warm outlet Shell kind "E" correction Fn = zero.765 Shell kind "J" correction Fn = 0.65 Contact us in case you do now not have MTD correction thing charts for divided flow. TEMA has one chart for a unmarried shell but it gives excessive values for the above examples and it's miles hard to read on this variety.

Question sixty one. How Is Plate Heat Exchangers Used In An Ammonia Refrigeration System?

Answer :

Plate warmth exchangers are broadly utilized in ammonia refrigeration structures, and that they can be tons smaller than the equivalent tubular exchanger can. They work excellent flooded. A flooded exchanger gadget needs a manner to separate the liquid from the vapor. A regular device has a vessel, which acts as knockout drum, accumulator, and header tank in a single, together with the heat exchanger. Liquid ammonia flows from the vessel to the exchanger, and liquid/vapor is lower back to the center of the drum. Vapor is removed from the top of the drum. The liquid/vapor aggregate from the exchanger has a decrease density than the liquid entering the exchanger, so gravity affords the using pressure to flow into the refrigerant.

Question sixty two. What Is An Effective Means Of Removing Silicon From Aluminum?

Answer :

Silicon is widely recognized for its chemical inertness, (i.E. It tends no longer to react with many other chemical substances). Depending on what form of silicon you're managing, this will or may not be clean to remedy. If the silicon is from a lubricant, it is probably the graphitic shape, that is soluble in a robust combination of nitric, and hydrofluoric acids, neither of which I could advocate for you to use...Nor hydrofluoric acid isn't always smooth to come back by. If it is silicon from an acidic form (likely some other form aside from a lubricant), you must strive ammonia. In either case, go away your acetone at domestic...It's going to NEVER paintings! UPDATE: An ammonia answer worked thoroughly in this situation.

Question 63. What Does The Catalystic Converter On An Automobile Really Do?

Answer :

A catalytic converter is a device that uses a catalyst to convert three harmful compounds in automobile exhaust gas into harmless compounds. The 3 dangerous compounds are:

Hydrocarbons (within the form of unburned gas)
Carbon monoxide (fashioned by the combustion of fuel)
Nitrogen oxides (created whilst the heat within the engine forces nitrogen in the air to mix with oxygen).
Carbon monoxide is a poison for any air-respiration animal. Nitrogen oxides result in smog and acid rain, and hydrocarbons produce smog. In a catalytic converter, the catalyst (within the form of platinum and palladium) is lined onto a ceramic honeycomb or ceramic beads which might be housed in a muffler-like package connected to the exhaust pipe. The catalyst enables to transform carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides returned into nitrogen and oxygen.

Question 64. Who Built The First Production Scale Pla (polylactic Acid) Facility?

Answer :

The first manufacturing scale PLA (polylactic acid) facility changed into constructed by using Cargill Dow in The Blair, Nebraska, and USA. The facility is designed to devour forty,000 bushels of corn in step with day and produce three hundred million lb/12 months of PLA.

Question sixty five. What Is The Largest Application For Surfactants?

Answer :

About 60% of overall surfactant market is composed of the detergent and cleaning merchandise market. These types of compounds are offered in large volumes at low prices.

Question sixty six. How Can You Separate Hydrogen Peroxide Into Hydrogen And Oxygen?

Answer :

This is without difficulty executed. Just expose hydrogen peroxide to air. The oxygen within the air will oxidize the hydrogen peroxide into its component gases. It occurs some distance too slowly for industrial or maximum other functions (an enzyme catalyst may be used to speed up the process). However, neither hydrogen nor oxygen is produced in this manner in industry. The enzyme catalyst is referred to as "catalase".

Question 67. What Is A Solvent?

Answer :

According to the US Solvent Council, "A solvent is a liquid which has the capacity to dissolve, suspend, or extract other materials with out chemical exchange to the cloth or solvent. Solvents make it possible to process, practice, easy, or separate substances.

Question sixty eight. What Is The Easiest Way To Extract Hydrogen From Water And The Safest Way To Store It?

Answer :

Electrolysis (because of this splitting using energy) of water is the technique for producing hydrogen from water. The most secure manner to commercially save it would be to apply a palladium "sponge", due to the fact palladium adsorbs several hundred instances it's very own volume in hydrogen. One could want to supply a compound with a very high surface area, which has a skinny coating of palladium. This kind of cloth is usually used as a catalyst in chemical processes.

Question 69. What Are The Three Classes Of Organic Solvents?

Answer :

Typically, organic solvents can be break up up within the following lessons: Oxygenated, Hydrocarbon, and Halogenated. Oxygenated solvents consist of alcohols, glycol ethers, ketones, esters, and glycol ether esters. Hydrocarbon solvents consist of aliphatics and aromatics. Halogenated solvents consist of those which might be chlorinated primarily.

Question 70. What Is Happening When Paint Dries?

Answer :

During the manufacture of paint, solvents are brought to make the paint thinner so that it could be carried out to diverse surfaces. Once the paint is carried out, the solvents evaporate and the resins and pigments that make up the paint for a thin, stable layer at the floor.