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PSE FINAL > PSE Core Concepts > Flashcards

PSE Core Concepts Flashcards

1
Q

When and in what country was paper invented?

A

105 AD China

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2
Q

What is the technical definition of paper?

A

A web consisting of cellulose fibers deposited from water suspension and then dried to form inter-hydrogen bonds

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3
Q

How much paper and board does the US manufacture each year?

A

74 million tons/yr

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4
Q

What % does the US manufacture of the total world production?

A

19%

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5
Q

How much paper and board is made each year?

A

400 million tons

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6
Q

What is the per-capita consumption of paper in the US each year, in lbs? How does this compare to China?

A

US - 500 lb/year
China - 165 lb/yr

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7
Q

What are the three major broad grades of paper? What % does each represent of the total production in the US each year?

A

Printing/ Writing: 30%
Tissue: 10%
Board: 60%

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8
Q

What is the largest grade of paper produced in the US, by weight?

A

Uncoated free sheet

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9
Q

What is the largest grade of paperboard produced in the US, by weight?

A

Containerboard

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10
Q

What is “market pulp”?

A

Thick sheets of raw fiber sold to mills that have paper machines but not a pulp mill

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11
Q

What is “fluff pulp”?

A

Long, hammer milled fibers that are used in absorbent consumer products

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12
Q

What are the two types of paperboard that go into a corrugated box?

A

Linerboard and corrugating medium

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13
Q

Of all the paper and board produced in the US each year, what % comes from recyled paper and board?

A

37%

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14
Q

What % of all paper and board produced in the US is recovered each year, instead of being sent to the landfill?

A

67%

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15
Q

Major structures/ areas in wood, if shown a photo of drawing.

A

Outer bark, inner bark, cambium, sapwood, heartwood, phloem, ray parenchyma, xylem

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16
Q

What function does each section of the tree have?

A

Outer bark- protect tree
inner bark- conduct sap
cambium- grows to make new fibers
sapwood- conducts water and minerals, stores nutrients
heartwood- support,
phloem- carries and dissolves sugars
ray parenchyma- carry nutrients

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17
Q

What is it in wood that actually ends up in paper?

A

Fibers

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18
Q

How are hardwoods and softwoods different, physically?

A

Harwoods cotain vessel elements and have shorter fibers
Softwoods have longer fibers

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19
Q

What different properties do hardwoods and softwoods contribute to a sheet?

A

Hardwoods create for better smoothness
Softwood fibers are stronger

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20
Q

Why do many trees have light and dark rings?

A

They indicate different growing seasons, lightrings are spring wood and dark rings are summerwood

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21
Q

What are the three main compounds/ polymers found in wood? What do they look like? What is their funtion? In general, what % by weight of the wood is each?

A

Cellulose: linear polymer, 50%
Hemi-cellulose: branched polymer, 25%
Lignin: network polymer, 25%

22
Q

What is paper, chemically?

A

A biopolymer, cellulose

23
Q

How many layers does a wood fiber have?

A
  1. P, S1, S2, S3
24
Q

What is the general goal of any pulping process?

A

Liberate fibers for papermaking

25
Q

Name the four general/broad categories of pulping used in the paper industry.

A

Mechanical pulping: no lignin removal, higher yield, low cost, low quality

Semi chemical pulping: some lignin removal

Chemical pulping: total lignin removal, low yield, high cost, high quality

repulping: recycled fibers

26
Q

What kinds of products is each type of pulping used for? What are the major steps involved in each?

A

Mechanical pulping: inexpensive printing grades

Semi-chemical: corrugating medium

Chemical: bleached grades

27
Q

What do the following abbreviations stand for?
SGW, PGW, TMP, CTMP

A

Stone-ground wood mechanical pulping
Pressurized-ground wood mechanical pulping
Thermomechanical pulping
Chemi-thermomechanical pulping

28
Q

What are the three main types of chemical pulping process? What major active chemicals are used in each process?

A

Kraft: NaOH + Na2S
Soda: NaOH
Sulfite: SO2

29
Q

What one chemical distinguished the kraft process from the soda process?

A

Na2S

30
Q

Where does the “kraft” process get its name?

A

Kraft is german for strong, and the kraft process makes for strong pulps

31
Q

Why is the kraft process the most predominant chemical pulping process in the world?

A

Acceptable for all wood species, efficient chemical recovery system, high quality pulp, low cost, comparatively simple

32
Q

What are the two main ways that a kraft pulping is carried out?

A

Batch digester or continuous digester

33
Q

What is “H-Factor”? How is it calculated? How is it used to control a kraft cook?

A

Time + Temperature

34
Q

What is “kappa number” what does it measure, and how is it used to control pulping?

A

Measures the lignin left in pulp after pulping.

35
Q

What is AA? EA? Sulfidity?

A

AA: Active Alkali –> NaOH + Na2S
EA: Effective Alkali –> NaOH + 1/2 Na2S
Sulfidity: Ratio of Na2S to AA

36
Q

What is “brownstock”?

A

unbleached and uncleaned pulp

37
Q

What is “black liquor”? Where is it produced? Where is it separated from fibers?

A

Spent white liquor filled with chemicals and biomass. It is produced in brownstock washing, where the black liquor is separated from the fibers

38
Q

What is the general goal of any bleaching process, for any pulp type?

A

Increase brightness

39
Q

What does D-E-D-E-D bleaching sequence stand for?

A

Chlorine Dioxide, extraction, etc.

40
Q

What is ECF bleaching? TCF?

A

ECF - elementally chlorine free, no ClO2
TCF - totally chlorine free, no chlorine at all

41
Q

What are the three basic steps involved in the conversion of black liquor to white liquor?

A

Evaporation, incineration, and recausticizing

42
Q

What is the job of the recovery boiler?

A

Combustion of black liquor to make white liquor in the kraft pulping process

43
Q

Why is evaporation of black liquor done using multiple effects?

A

Save steam, energy

44
Q

What is refining? Why is it carried out on papermaking stock? What effect does it have on fibers? On the paper sheet?

A

Refining improves sheet strength. Pulp fibers cannot deliver enough wet or dry strength to produce a successful sheet in their natural state

45
Q

What is freeness? What does it measure? How is it used in the paper mill?

A

How freely water drains from a fiber slurry. This is an indication of the amount of refining via the generation of fines from P and S1 layers

46
Q

What are the basic categories/types of additives used for papermaking? What is the role of each type?

A

Retention Aids
Sizing agents
Fillers
Strength Additives
Dyes and Pigments
pH Control Additives
Specialty Additives
Operation Improvement

47
Q

What is the headbox? What are its roles on the paper machine?

A

Holds/ delivers stock onto the paper machine wet end

48
Q

What are the three main forces used to remove water on the paper machine wet end?

A

Gravity, vacuum, and press

49
Q

What are the three main types of paper machine wet ends?

A

Fourdrinier, top-wire former, and gap former

50
Q

Identify the main features and components of the forming section, the vacuum section and the press section.

A
51
Q

What is formation? What affects it?

A

How the fibers are oriented in the mat, microturbulence improves formation

PSE FINAL (2 decks)

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