Section 5 - Reduction System Flashcards
Draw the reduction system
Page 29 fig 13
What does the reduction system consist of
smooth reduction rolls and sifting machines
What is the aim of the reduction system
To reduce the various grades of the endosperm released on the breaks to flour, without damaging the bran and germ
What is reduction
Gradual grinding and sifting of various particle sizes until they are fine enough for flour
What differential do reduction rolls run at
1.25:1
What do sifting machines do
Dress out the flour at each stage down the system
Grade the stocks that need further grinding
Separate the stocks which eventually go to wheatfeed
What does the reduction system do
Grinds purified semolina and middlings on numerous stages of smooth rolls
Sifts out and dresses flour made by these rolls to make the final separation
How many sieves can be in each section
Up to 30
How many reduction passages are there now
10, fallen from 13 in the 50s
What did the total surface fall from and to
40mm/100kg/24hrs to 8-10mm
How is a low reduction passage surface possible
A result of flake disruptors, impact detachers, and high capacity sifters, with lower stock temps
What surface is used in a long system
up to 40mm/100kg/24h
What is the roll of a detacher
To break up clumps of endosperm flakes so they can be sifted
Whats another name for a detacher
Flake disrupter
Where do you find flake disrupters
Head reduction passages between rolls and sifters
What factors enabled shorter systems to be developed
Introduction of pneumatic mill (cooler stock allow more work without the risk of overheating)
Improvement in the roller mill (Replacement of brass bearings with cooler trouble free roller bearings allow rolls to be run at higher speeds)
Provision of efficient water cooling system for grinding rolls
Improvements in capacity and dressing efficiency of plansifter
detachers
peelers or debranners
What is the advantage of a short system
Less plant is required for a given capacity - smaller buildings are less expensive and easier to maintain keep clean and sueprvise
What is the roll surface on a short system
10mm/100kg/24h
What are pin mills used for
To break up flakes while also grinding reduction stocks without creating starch damage
What are the advantages of a roll water cooling system
Cooler grinding of stocks
less condensation
improved dressing of stock
consistent grinding results
aid to improved water absorption
What are the disadvantages of a roll water cooling system
Capital cost of installation
Additional maintenance costs
increased energy costs
water leaks
What is the aim of flour dressing?
To extract any flour released on reduction rolls and ensure remaining stocks are completely free from any flour or dust
What is the method of dressing
Plansifter
Where is starch damage usually obtains
Head end of reduction rolls
