Category: Pulp & Paper Objective Questions

Pulp and Paper Multiple Choice Questions on “Mechanical Sensors”.

1. __________ sensors are utilised to measure variables such as point, velocity, acceleration, force, press, levels and flow.
a) Humidity
b) Optical
c) Thermal
d) Mechanical
Answer: d
Clarification: Mechanical sensor is an object whose function is to detect changes in its environment, and then provide a corresponding output. It’s a type of transducer; sensors might provide various types of output, but typically utilize electrical or optical signals.

2. __________ sensors rely on a change of capacitance, resistance, inductance, or reluctance.
a) Point
b) Humidity
c) Proximity
d) Thermal
Answer: a
Clarification: A point sensor is any device that permits point measurement. It could either be an absolute point sensor or a relative one (displacement sensor). Point sensors could be linear, angular, or multi-axis.

3. A potentiometric displacement sensor utilizes a wire of high resistance with a wiper in electrical contact with the wire.
a) True
b) False
Answer: a
Clarification: As the object moves across the wire, the resistance of the circuit changes. By measuring the resistance, the point of the object along the wire is known.

4. Variable inductance is achieved by the utilization of __________ core in the shape of a rod which is wraped by a hollow coil of wire.
a) Ferrimagnetic
b) Ferromagnetic
c) Paramagnetic
d) Diamagnetic
Answer: b
Clarification: As the ferromagnetic core enters the coil the inductance of the coil is replaced. With reluctance sensors, the magnetic flux coupling b/w 2 or more coils is varied by a ferromagnetic core. Inductance is a calculation that relates electrical flux to the current.

5. __________ sensors is a type of transformer and are the basis of the prevalent L.V.D.T . The signal is easily conditioned to give out a D.C. voltage that in linearly proportional to point over part of the range of motion of the core.
a) Speed
b) Temperature
c) TIR
d) Reluctance
Answer: d
Clarification: It’s a type of sensor that are the basis of the prevalent L.V.D.T. linear variable differential transformer. The sensitivity could be on the order of 0.001 mm movement.

6. __________ could be utilized as a point sensor by measuring a time pulse of __________ takes to echo back to the transmitter. It is similar in principle to a radar.
a) Radiation
b) Reflection
c) X- ray
d) Ultrasound
Answer: d
Clarification: Ultrasounds are sound waves with frequencies which are greater than the upper audible limit of human hearing. Ultrasound is no different from ‘normal’ (audible) sound in its physical properties, except in that humans couldn’t hear it. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

7. The __________ factor is the relative change in resistance divided by relative change in length i.e., the definition of strain.
a) Screw
b) Gauge
c) Pit
d) Kraft
Answer: b
Clarification: Strain gauge is the ratio of relative change in electrical resistance R, to the mechanical strain ε. Metal strain gauges have a gauge factor of about 2; thus a strain of 0.1% would cautilise a 0.24 Ω change in a 120 Ω strain gauge.

8. If a fluid is at rest, one refers to static _________ If a fluid is in motion, one refers to dynamic _________ which is a function of the motion of the fluid.
a) Pressure
b) Gravitational force
c) Viscosity
d) Density
Answer: a
Clarification: The force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure

9. Strain ___________ could be mounted on diaphragms to measure pressure; this method has been miniaturized onto integrated circuits.
a) Sensors
b) Lobes
c) Gauges
d) Gears
Answer: c
Clarification: The most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate.

10. The temperature of a heated metal filament depends on the gas pressure since the gas molecules could conduct heat from the filament.
a) True
b) False
Answer: a
Clarification: Very less pressure i.e., very high vacuums, which signifies a gas phase, requiring specialized techniques. Pressure below 10_-3 could be measured with ionization gauges.

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Pulp and Paper Multiple Choice Questions on “Wood Chip Measurement”.

1. Which is the ideal definition in bulk density?
a) Natural-dry weight of pulp
b) Oven-dry weight of chips
c) Natural-dry weight of chips
d) Oven-dry weight of pulp
Answer: b
Clarification: The bulk density is the oven-dry weight of chips (or sawdust, or other wood residue) contained in a given volume of space.

2. Bulk density of the chips depend on the specific gravity of wood source.
a) True
b) False
Answer: a
Clarification: The bulk density is the oven-dry weight of chips (or sawdust, or other wood residue) contained in a given volume of space.

3. Bulk density of the chips depends on the chip geometry.
a) True
b) False
Answer: a
Clarification: The bulk density is the oven-dry weight of chips (or sawdust, or other wood residue) contained in a given volume of space.

4. Bulk density of the chips depends on the chip size distribution.
a) True
b) False
Answer: a
Clarification: The bulk density is the oven-dry weight of chips (or sawdust, or other wood residue) contained in a given volume of space.

5. According to the rule of thumb what is the value of chips yielded by the wood of 1 cubic meters?
a) 3.5 cubic meters
b) 2.6 cubic meters
c) 0.2 cubic meters
d) 6.8 cubic meters
Answer: b
Clarification: Rules of thumb are derived in order to identify an operating window that minimizes the volatilization of metals during thermochemical conversion of CCA in treated wood, while ensuring a good quality of charcoal product.

6. How much a bone dry unit is equal to in sawdust?
a) 3600 lb
b) 12000 lb
c) 2400 lb
d) 8000 lb
Answer: c
Clarification: A bone dry unit is the equal to 2400lb of sawdust.

7. How many units does a bone density unit of packed Douglas chips contain?
a) 400
b) 600
c) 800
d) 200
Answer: d
Clarification: A Bone density unit, B.D.U. of packed Douglas chips occupies approximately 200 cubic feet

8. A Kraft unit is 200 cubic. feet. of wood chips, sawdust, or other wood particles.
a) True
b) False
Answer: a
Clarification: A unit is considered as a mixture of wood chips, sawdust, or other wood particles. It all weighs to 200 cubic feet.

9. One unit of Doughlas-fir or western hemlock sawdust is about __.
a) 10 cubic feet of solid wood
b) 300 cubic feet of solid wood
c) 1000 cubic feet of solid wood
d) 80 cubic feet of solid wood
Answer: d
Clarification: One unit of Douglas-fir or western hemlock sawdust is about 80 cubic feet of solid wood.

10. What is the value of after converting B.D.U. to cubic meter of wood chips.
a) 3.55
b) 2.3598
c) 1.06
d) 6.3
Answer: d
Clarification: Approximate conversion factors of wood 0.45 specific gravity in various forms. It is converted by multiplication action.

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Pulp and Paper Multiple Choice Questions on “Recovery Boiler”.

1. The purpose of the recovery boiler is to recover the inorganic chemicals as smelt, burn the organic chemicals so they are not discharge from the mill as pollutants, and recover the heat of combustion in the form of heat.
a) True
b) False
Answer: a
Clarification: The purpose of the recovery boiler is to recover the inorganic chemicals as smelt, burn the organic chemicals so they are not discharge from the mill as pollutants, and recover the heat of combustion in the form of heat. Smelt is sodium carbonate and sodium sulfide.

2. There are three zones in recovery boilers; which are as follows in top to bottom order?
a) Oxidation, drying and reducing zone
b) Reducing, drying and oxidation zone
c) Drying, oxidation and reducing zone
d) Drying, reducing and oxidation zone
Answer: a
Clarification: The upper section is the oxidizing zone, the middle section is the drying zone, and the bottom section is the reducing zone where, in a bottom bed of char, the sulphur compounds are converted to Na₂S.

3. What is the full form of ESP in Recovery boiler?
a) Emergency shutdown point
b) Emergency shutdown procedure
c) Emergency start procedure
d) Emergency shared procedure
Answer: b
Clarification: Due to the possible adverse reaction of molten smelt with water, all recovery boilers have an ESP in the event of trouble.

4. The newest recovery boilers may support 2500-3000 tons of pulp production per day.
a) True
b) False
Answer: a
Clarification: The recovery boiler is the largest and the most expensive equipment in the Kraft mill costing over 100 million dollars.

5. Which of the following is the chemical react. in the recovery boiler in addition to combustion?
a) 2NaOH + CO₂U → Na₂CO₂+H₂O and Na₂SO₂ +4C ↔ 6Na₂S + 4CO
b) 2NaOH + CO₂ → Na₂CO₂ and Na₂SO₂+4C ↔ 4CO
c) 2NaOH + CO₂ → Na₂CO₂+H₂O₂ and Na₂SO₂+4C ↔ Na₂S +4CO₂
d) 2NaOH + CO₂ → Na₂CO₂+H₂O and Na₂SO₂+4C ↔ Na₂S +4CO
Answer: d
Clarification: The lower zone is deficient in oxygen, so reduction reaction occurs. This allows the sulfur (S) in the smelt to occur as Na₂S₂O₂ or Na₂SO₂, which could be unsuitable for fresh liquor.

6. Which of the following is the reaction which takes place in the Oxidation zone in the Recovery Boiler?
a) CO+1/2O₂ → CO₂
b) Organics →C+CO+H₂
c) C+H₂O → CO+ H₂
d) 2C+ O₂→2CO
Answer: a
Clarification: Oxygen is made to react with the species. Simple oxidation reaction.

7. Which of the following is the reaction which takes place in the Drying zone in the Recovery Boiler?
a) Organics→C+CO+ H₂
b) CO+1/2 O₂→ CO₂
c) C+ H₂O→CO+ H₂
d) 2C+ O₂→2CO
Answer: a
Clarification: This is the part where black liquor is injected to the system.

8. Which of the following is the reaction which takes place in the Reduction zone in the Recovery Boiler?
a) Na₂SO₂+4C→Na₂S+4 CO
b) 2C+ O₂→2CO
c) CO+1/2 O₂→CO₂
d) H₂S+1/2 O₂→SO₂+ H₂O
Answer: a
Clarification: This is the part where sulfur compounds are converted to Na₂S.

9. Fill in the blank.
thermal efficiency =(__________)/total heat input
a) steam to heat
b) heat to steam
c) heat recovery
d) cogeneration
Answer: b
Clarification: Many of the heat loss has occurred as steam in flue gases from water in black liquor.

10. What is cogeneration?
a) Producing electricity from steam
b) Producing steam from electricity
c) Producing light from steam
d) Producing power from steam
Answer: a
Clarification: Cogeneration is the process of producing electricity from steam and utilizing the waste heat as steam in chemical processes.

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Pulp and Paper Multiple Choice Questions on “Fiber Penetration and Approach”.

1. _________ is a measure of the solids content and the dry weight of fibers and other solids divided by the net wet weight of stock weight and expressed as a percentage.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: b
Clarification: Consistency is a measure of the solids content and the dry weight of fibers and other solids divided by the net wet weight of stock weight and expressed as a percentage. The consistency of stock at the headbox can be as low as 0.3%.

2. _________ are large mixing vessels utilized to dis-integrate purchased pulp, broke, and recycled paper into a relatively dilute slurry which can be processed inside the mill.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: c
Clarification: Hydrapulpers are large mixing vessels utilized to dis-integrate purchased pulp either wet lap at 50 percent solids or dry sheets at 80-85 percent solids, broke is the paper that must be re-processed inside the mill, and recycled paper into a relatively dilute slurry which can be processed within the mill.

3. The _________ is a disturbed storage test that holds back stock prior to being sent to the paper making process.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: a
Clarification: The machine chest is a disturbed storage test that holds back stock prior to being sent to the papermaking process. If the any other equipment shuts down temporarily, the paper machine could continue running by drawing pulp from the machine chest.

4. The _________ is a mini box in which pulp enters prior to the fan pump for utilized in the paper machine.
a) Machine chest
b) Consistency
c) Hydrapulper
d) Stuff box
Answer: d
Clarification: The stuff box is a mini box that pulp enters prior to the fan pump for use in the paper ma chine. Pulp enters at a regulated 3-4 percent consistency through a stock or stuff valve and maintains a constant head to precisely control the flow rate to the fan pump.

5. Stock and re-circulated white water are not mixed together at the primary fan pump, a very large pump.
a) True
b) False
Answer: b
Clarification: Stock and re-circulated white water are not mixed together at the primary fan pump, a very large pump.

6. The _________ is a device for the stock going to a paper machine with a partial vacuum.
a) Machine chest
b) Deculator
c) Hydrapulper
d) Stuff box
Answer: b
Clarification: The deculator’s a device for the stock going to a paper machine with a partial vacuum. This causes small air bubbles that are entrained in the stock to expand, separate from the stock, and come to the surface of the stock. Dissolved gases will also be removed to some extent.

7. Pulp is screened through small holes or slots to remove shives, dirt, and other large particles. The reject material is usually refined and screened, and the final rejects discarded to the sewer system.
a) True
b) False
Answer: a
Clarification: Pulp’s screened through small holes or slots to remove shives, dirt, and other large particles. The rejected material is usually refined and screened, and the final rejects discarded to the sewer system. Vibratory flat screens and rotary screens are open, gravity flow systems, which could have high frequency vibration to help the screening action.

8. _________ were introduced in the 1950s for headbox approach systems and were enclosed, pressurized screens of high capacity.
a) Lining screen
b) Content screen
c) Head box
d) Pressure screens
Answer: d
Clarification: Pressure screens were introduced in the 1950s for headbox approach systems and were enclosed, pressurized screens of high capacity which demonstrates the principle of operation as do Plates 30 to 32. One crucial modification was that the reduction in the screen slot width from 0.50 mm (0.020 in.) prior to 1970, which is still utilized for corrugating medium.

9. What is the name of the instrument?

a) Rotator cleaner
b) Centrifugal cleaner
c) Binary cleaner
d) Conical cleaner
Answer: b
Clarification: Centrifugal energy which is produced when parts are rotated inside a sealed process chamber, provides thorough penetration, solubilization, and contaminant removal .

10. What is the name of the hidden content?

________ = {(weight of dry material) / (weight of suspension)} x 100%

a) Stuff box
b) Consistency
c) Fan pump
d) Machine chest
Answer: b
Clarification: Consistency’s a calibration of the solids content which is the dry weight of fibers and other solids divided by the total wet weight of stock weight and expressed as a percentage. It could be as low as 0.3%.

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Pulp and Paper Multiple Choice Questions on “Kraft Liquor Calculations”.

1. The _________ is the sum of all of the Na salts in the liquors (as Na₂O) that contribute to AA in the kraft cycle, specifically NaOH, Na₂S, Na₂CO₃, and Na₂O.
a) Base
b) Total alkali
c) Total acid
d) Buffer
Answer: b
Clarification: The total alkali’s the sum of all of the Na salts in the liquors (as Na₂O) that are capable of being converted to AA in the kraft cycle, specifically NaOH, Na₂S, Na₂CO₃, and Na₂O.

2. _________ is the sum of all of the bases in the white liquor that could be titrated with strong acid.
a) Total titratable alkali
b) Active alkali
c) Total chemical
d) Total alkali
Answer: a
Clarification: T.T.A. is the sum of all of the bases in the white liquor that could be titrated with strong acid. It’s considered as NaOH, Na₂S, and Na₂CO₃ (as Na₂O), although small amounts of Na₂CO₃.

3. The sum of the active ingredients in the pulping process is called active alkali.
a) True
b) False
Answer: a
Clarification: White liquor’s a strongly alkaline sol. mainly of NaOH and Na₂S. It’s utilized in the first stage of the Kraft process in which lignin and hemicellulose are separated from cellulose fiber for the production of pulp.

4. _________ is the sum of Na chemicals that will produce OH^– during kraft pulping.
a) Active akali
b) Effective alkali
c) Causticity
d) Sulfidity
Answer: b
Clarification: NaOH is completely ionized and for every 2 sodium atoms of Na₂S, there’ll be one OH^– produced.

5. In the _________ sulfidity’s the ratio of Na₂S to the active alkali, expressed as a %.
a) Green liquor
b) Red liquor
c) White liquor
d) Black liquor
Answer: c
Clarification: Generally, a mill runs in the vicinity of 25 to 30% sulfidity, depending largely on the wood species pulped. Sulfidity inc. the rate of de-lignification, which occurs by nucleophilic action of the hydrosulfide anion (H.S.) and appears to protect cellulose against degradation.

6. The _________ is the ratio of NaOH to active alkali, expressed as a %.
a) Active alkali
b) Liquor to wood ratio
c) Causticity
d) Sulfidity
Answer: c
Clarification: The causticity’s the ratio of NaOH to active alkali, depicted as a percentage; therefore, causticity + sulfidity = 100%. The term sulfidity’s utilizes much more than the term causticity, and both give the same information.

7. The _________ is the ratio of NaOH to NaOH and Na₂CO₃.
a) Sulfidity
b) Causticity
c) Causticizing efficiency
d) Reduction efficiency
Answer: c
Clarification: This is a calculation of how efficient causticizing is; it represents the percentage of the Na₂CO₃ from the recovery boiler that is converted back into useful NaOH cooking chemical. A value of 77-80% is typical.

8. The ratio of Na₂S to the sum of Na₂S and Na₂SO₄ in green liquor expressed as a percentage. What’s the name of the topic?
a) Sulfidity
b) Causticity
c) Causticizing efficiency
d) Reduction efficiency
Answer: d
Clarification: The reduction efficiency’s the ratio of Na₂S to the sum of Na₂S and Na₂SO₄ in green liquor expressed as a %. This’ a calc. of the reduction efficiency in the recovery boiler. This value should be high, as 95 percent, and is not routinely measured in the mill.

9. Derive the conversion factor of 0.775 utilized to express the weight of NaOH on an Na₂O basis.
a) 0.775 g Na₂O
b) 3.254 g Na₂O
c) 15.775 g Na₂O
d) 0.456 g Na₂O
Answer: a
Clarification: 1st, the molar relationship b/w these 2 species is expressed.
2 NaOH andbarr; Na₂O + H₂O
Gravimetric factor’s determined as follows:
1g NaOH X 1 mol NaOH(40g NaOH)^-1 x 1 mol Na₂O(2 mol NaOH)^-1 x 62g Na₂O(1 mol Na₂O)^-1 = 0.775g Na₂O.

10. Fill in the blank.
________ = {(NaOH) / (NaOH + Na₂CO₃)} x 100%
a) Na₂CO₃
b) NaOH
c) CO₃
d) Na
Answer: b
Clarification: The causticizing efficiency is the ratio of NaOH to NaOH and Na₂CO₃. This’s a calculation of how efficient causticizing is; it represents the percentage of the Na₂CO₃ from the recovery boiler that’s converted back into useful NaOH cooking chemical. A value of 77 to 80% is typical.

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Pulp and Paper Multiple Choice Questions on “Surface Tension and Sizing”.

1. Identify the equation used to calculate pore sizes.

l² = rty cosθ/2ŋ

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: a
Clarification: Lucas used this equation to calculate pore sizes in paper based on the speed of the rise of organic liquids in paper strips. Lucas used organic liquids since they would not change the pore sizes by swelling or hydration.

2. Identify the equation to give actual capillary action.

P^α – P^β= 2y / R

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: b
Clarification: This equation is modified to give the actual capillary rise for H₂O by solving for the force of H₂O and the wettability of the glass by the H₂O. If the H₂O completely wets the glass. Here, r is the capillary tube radius, p is the density of a phase, g is the acc. due to gravity, and h is the height of the H₂O.

3. Identify the equation to give actual capillary action.

y = 1/2(ρ_α – ρ_β)ghr / cosθ

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: b
Clarification: This equation is modified to give the actual capillary rise for H₂O by solving for the force of H₂O and the wettability of the glass by the H₂O. If the H₂O completely wets the glass. Here, r is the capillary tube radius, p is the density of a phase, g is the acc. due to gravity, and h is the height of the H₂O.

4. 3 contact angles of a droplet on a flat surface

a) True
b) False
Answer: a
Clarification: Either at 90 degrees or an acute angle or an obtuse angle. Contact angel is the angle, normally measured through the liquid, where a liquid–vapor interface contacts a solid surface.

5. Find the hidden term

if adhesive > cohesive then 0 degree

a) 10 degrees
b) 180 degrees
c) 100 degrees
d) 90 degrees
Answer: d
Clarification: The contact angle is a measure of the adhesive force of the liquid with the surface relative to the cohesive forces in the liquid. It is generally measured through the liquid, where a liquid–vapour interface contacts a solid surface.

6. Find the hidden term

if adhesive > cohesive then 90 degree

a) 10 degrees
b) 180 degrees
c) 100 degrees
d) 90 degrees
Answer: b
Clarification: The contact angle is a measure of the adhesive force of the liquid with the surface relative to the cohesive forces in the liquid. The angle, conventionally measured through the liquid, where a liquid–vapour interface contacts a solid surface.

7. _________ is easily wetted by H₂O and, H₂O on _________ gives a low contact angle that approaches zero; this causes the water to be drawn into the capillaries. [/expand]
a) Starch
b) Lignin
c) Cellulose
d) Pulp
Answer: c
Clarification: Cellulose is easily wetted by H₂O and, H₂O on cellulose gives a low contact angle that approaches zero; this causes the H₂O to be drawn into the capillaries.

8. Internal sizing agents are generally _________ materials. The polar portion attaches to the fiber or fines directly through a covalent bond or indirectly through a caustic element such as alum.
a) Amphoteric
b) Amphitaric
c) Non polar
d) Polar
Answer: b
Clarification: Internal sizing agents are generally amphipathic having polar and nonpolar moieties on the same molecule materials. The polar portion more importantly, it is chemically reactive attaches to the fiber or fines directly through a covalent bond.

9. Identify the equation used to calculate pore radius from which water will condense.

r = (2yV) / RT ln (p_o/p)

a) Lucas
b) Wettability
c) Kelvin
d) Pascal
Answer: a
Clarification: A water droplet with a (+ve) radius has a slightly higher vapor pressure than a flat surface of H₂O. When with a (-ve) radius has a lower vapor pressure, which allows condensation to occur.

10. Inverse _________has been utilized to characterize surface energy; in pulp and paper this has been accomplished with treated and untreated pulps.
a) Gas chromatography
b) Silver test
c) Stone test
d) Sulfurication
Answer: a
Clarification: It’s a common type of chromatography utilized in analytical chemisty for separating and analyzing compounds that could be vaporized without decomposition. Typical uses of G.C. include testing the purity of a particular substance, or separating the different components of a mixture.

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