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6.

Technical calculations

Industrial production requires a daily check of the plant capacity, product output yield, consumption of energy etc. by collection of various production data and calculations. Examples of some useful technical calculations are given in the following sections.

6.1.

Evaporation and product output

The symbols used in the examples consist of three letters, the meaning of which is as follows:
First letter Second letter Third letter
E = evaporator F = feed R = rate (kg/h)
D = spray dryer E= evaporation S = total solids (%)
B = fluid bed P = product
Table. 6.1. Evaporation, symbols used in the examples consist of three letters, the meaning of which is as follows
a) Evaporation and product rate from the evaporator:
[6,1]
[6,2]
[6,3]
[6,4]
[6,5]
b) Evaporation and product rate from the spray dryer:
[6,6]
[6,7]
[6,8]
[6,9]
[6,10]
[6,11]
c) Evaporation and product rate from the fluid bed:
[6,12]
[6,13]
[6,14]
[6,15]
[6,16]
[6,17]
d) Example:
 
Evaporator feed rate: EFR = 50000 kg/h
Total solids of evaporator feed: EFS = 12.2 %
Total solids of the concentrate: EPS = 48.0 %
Total solids of powder from spray dryer: DPS = 94.2 %
Total solids of powder from fluid bed: BPS = 97.2 %
 
Notice that DFR = EPR, BFR = DPR, DFS = EPS and BFS = DPS.
The results are given in table below..
Calculated Calculation Result Equation
EPR = DFR 50000x12.2/48 = 12708.3 [6,3] and [6,6]
 EER 50000-12708.3 =  37291.7 [6,1]
DPR = BFR 12708.3x48/94.2 = 6475.6 [6,8] and [6,12]
DER 12708.3-6475.6 = 6232.7 [6,7]
BPR 6475.6x94.2/97.2 = 6275.7 [6,15]
BER 6475.6-6475.7 =  199.9 [6,13]
Table. 6.2.
There are examples of calculations in all the following sections and the results are rounded up to the reasonable decimals. However, the calculations have been made using the exact figures.
6.2.

Heating of atmospheric air

If an amount Aa of atmospheric air with humidity ya is to be heated from a temperature t1 to a temperature t2, the amount of heat Q necessary is calculated by the equation:
[6,18]
If Aa =30000 kg/h, ya =0.009 kg/kg, t1=15°C and t2=200°C then from equation [3,8] ca1=0.240, ca2=0.245 and from equation [3,10] cv1=0.445 and cv2=0.463 kcal/kg/°C. The result is:
[6,19]
6.3.

Mixing of two air stream

Two quantities of air A1 and A2, with humidities y1 and y2 and temperatures t1 and t2 are to be mixed, the temperature t3 of the mixed air calculated by a simplified method is as follows:
[6,20]
Example: 
A1 = 50000 kg/h, A2 = 10000 kg/h, t1 = 90°C, t2 = 20°C,
y1 = 0.0442 kg/kg and y2 = 0.007 kg/kg:
[6,21]
For a more precise calculation, heat capacities of air must be considered. From equation [3,8] values are ca1 = 0.240 kcal/kg/°C at 90°C and ca2 = 0.241 kcal/kg/°C at 20°C and calculation of the resulting air humidity y3 and enthalpy h3 is by:
[6,22]
[6,23]
The enthalpy of both components using heat capacities of water vapour from equation [3,10] at 20°C cv1 = 0.445,at 90°C cv2 = 0.451 and using equation [3,11]:
[6,24]
[6,25]
The enthalpy of the resulting air mixture is then:
[6,26]
[6,27]
Using equation [6,22] which is another form of equation [3,11] the resulting temperature t3 is:
[6,28]
The values ca3 and cv3 are calculated from equation [3,8] and equation [3,10] using the approximate mixing temperature calculated by [6,19], i.e. 78°C which are 0.241 and 0.450 kcal/ kg/°C respectively.
[6,29]
In comparison with the simplified calculation there is a difference of 1.04°C.
6.4.

Dry air rate, water vapour rate and air density

Using figures from the previous example and equations [3,5] through [3,7] and [3,13], the dry air rates Adn, water vapour rates Avn and air densities ρn are:
[6,30]
The volume of air V is calculated as follows:
[6,31]
Thus:
 
V1 = A1/ρ1 = 50000/0.9484 = 52722 m3/h
V2 = A2/ρ2 = 10000/1.1997 = 8336 m3/h
V3 = A3/ρ3 = 60000/0.9804 = 61199 m3/h
6.5.

Air velocity in ducts

Using a Pitot tube (Fig.6.1.) it is possible to measure the static pressure Ps, dynamic pressure Pd and total pressure Pt.
Pitot tube with U-tube
Fig.6.1. Pitot tube with U-tube
[6,32]
[6,33]
and,
[6,34]
where: 
Pd = dynamic pressure in mm water gauge
g = gravity constant 9.81 m/s²
ρ = density of air kg/m³
v = air velocity in m/s.
6.6.

Air flow measurements

In practice, it is not easy to measure exactly the amount of air passing through a duct, filter or spray dryer. The methods available are listed below:
 
a) Measuring the air velocity and duct area.
 
If the air velocity is measured by Pitot tube or by wind or hot wire anemometer in a duct of SA
area, then the volume of air flow V in m3/h is:
[6,35]
Knowing the air temperature t and humidity y, the air rate A in kg/h can be calculated using equations [3,12], [3,13] and [6,23]. In a similar way, for round ducts of diameter D, the equation is:
[6,36]
b) Measuring pressure drop across the cyclone:
[6,37]
where: 
A = air rate in kg/h
D = cyclone diameter in m
n = number of cyclones
ρ = density of air in kg/m3
ΔP= pressure drop across the cyclone in mm WG
K = cyclone constant
 
The cyclone constant depends upon the cyclone design and powder loading in air. For various types of the cyclones constants lay between 200 - 1000, the exact values being proprietary manufacturer know-how. However, if the air flow has been measured by one of the described methods and at the same time the pressure drop over the cyclone measured the cyclone constant can be calculated backwards and used in later routine measurements.
 
c) Measuring the amount of heat necessary for air heating:
 
If air is heated from a temperature t1 to a temperature t2 the amount of air can be calculated from the amount of heat used and the temperature difference. In principle the same method of calculation is used for steam, oil, gas and electric air heaters.
 
The basic equation is:
[6,38]
where: 
E = efficiency of the heater
t1 = air temperature at heater inlet
t2 = air temperature at heater outlet
ca1 = heat capacity of air at heater inlet
ca2 = heat capacity of air at heater outlet
X = the heat consumed kcal/h.
 
Calculation of X for various types of heaters is explained below.
 
c1) Measuring of the condensate from the steam heater:
 
X for the equation [6,30] is:
[6,39]
where: 
W = amount of the condensate in kg/h
hs = enthalpy of steam at heater inlet in kcal/kg
hc = enthalpy of the condensate (which is equal to the temperature)
 
c2) Measuring of gas or oil consumption:
 
X for equation [6,30] is:
[6,40]
where: 
G = amount of oil in kg/h or gas in Nm3/h
Qh = caloric value of the fuel in kcal/kg or kcal/Nm3.
 
c3) Measuring of consumption of electricity:
 
X for the equation [6,30] is:
[6,41]
d) Measuring the water evaporation rate:
 
The dryer is operated on water under constant t1 and t2 for at least 1 hour to obtain stable conditions. The amount of water, supplied to the dryer over a period of time is measured. The most suitable way is to measure the level difference h in a cylindrical feed tank of diameter D. The volume and weight of the evaporated water and the evaporation rate are:
[6,42]
[6,43]
[6,44]
where: 
D = feed tank diameter in m
h = level difference in m
t = time of measuring in s
ρw = density of water at feed temperature tf in °C
DER = rate of evaporation in kg/h.
 
The drying air rate A is then:
[6,45]
where: 
t1 and t2 = the air inlet and outlet temperatures,
ca1 and ca2 = heat capacities of air at t1 and t2,
cv2 = heat capacity of water vapour at t2
tf = feed temperature,
Ar = surface area of the dryer in m²,
ts = spray dryer surrounding temperature,
K = radiation constant in kcal/m²/h.
6.7.

Barometric distribution law

The barometric pressure in an altitude of m meters above sea level is calculated:
[6,46]
where: 
p0 = barometric pressure at sea level at 0°C,
M = molecular weight of air (= 0.029 kg/mol),
g = gravity constant (= 9.807 m/s2),
R = gas constant (=8.3144 J/K/mol)
T = absolute temperature in °K, and
m = altitude in m.
6.8.

The heat balance of a spray dryer

The spray dryer in operation is a system where air and product move through under changing temperatures and humidities and as the product is concerned, also changing physical properties. Entering components are: drying gas, which is usually heated ambient air, some auxiliary air flows (as cooling air, fines transport air etc.) and the feed to be dried. The humidity of the entering air corresponds to the ambient air humidity, possibly increased somewhat by moisture generated during combustion (in case of direct gas heating) or by moisture picked up by the air on passage through the building. The feed is the milk concentrate. Exhaust air and powder leave the system. The exhaust air is made up of all entering air flows plus water formed from the evaporation and besides it contains also some traces of the dried solids (fine particles). The dry products in powder form contain practically all the feed solids, but have residual moisture. The amount of air necessary to evaporate a required amount of water from a given amount of feed can be found by calculating all the individual heat requirements necessary for evaporating the water, heating or cooling each individual component from its inlet to its outlet temperature, while compensating for heat losses. The sum of these contributions is then recalculated into the air rate on the basis that the drying air enters the system with a temperature t1 and leaves with a temperature t2.
 
The following example is a demonstration of the calculation of the heat requirement and drying air rate of a spray dryer as specified below by points a) through g). The source of drying air is ambient thus the inlet humidity is considered as ambient humidity ya:
 
a) The drying air of the inlet temperature t1 and humidity ya, and the drying air rate Ad (which has to be calculated),
b) The auxiliary cooling air for the atomizing device of temperature tc, humidity ya and rate Ac,
c) The fines transport air of temperature tt, humidity ya and rate At,
d) The feed concentrate of temperature tf, rate DFR and solids content DFS,
e) Recycled fines, collected from all cyclones, into the dryer in the amount given by ratio R to the total powder production and temperature tt (i.e. the same as of fines transport air).
 
The mass flows at the outlet of the system are:
 
f) The exhaust air consisting of all the entering air flows plus the moisture generated during drying, having final temperature t2 and humidity y2,
g) The powder consisting of the feed solids plus some residual moisture.
 
For the calculation, the operating conditions at the inlet and the outlet have to be first set. Product experience, knowledge of the drying installation and applied process is used to estimate the permissible air inlet temperature and feed total solids content and the required air outlet temperature for the specified powder moisture. Besides there is also some heat loss due to the radiation from the equipment surface of area SA. The radiation coefficient is K and the surrounding temperature around the dryer is estimated to be 20°C above the ambient temperature. Having fixed the operating parameters the heat balance can be calculated as follows:
 
Heat of evaporation:
[6,47]
Heat of product solids:
[6,48]
Heat of cooling air:
[6,49]
Heat of fines transport air:
[6,50]
Heat of fines:
[6,51]
Heat of radiation loss:
[6,52]
The sum of heat requirements:
[6,53]
The drying air rate:
[6,54]
Example: Calculate the drying air rate and size of dryer for following duty:
 
Feed rate: DFR = 4000 kg/h
Feed concentration: DFS = 48 %
Feed temperature: tf = 60 °C
Product solids content: DPS = 95 %
Ambient temperature: ta = 15 °C
Ambient humidity: ya = 0.01 kg/kg
Inlet temperature: t1 = 200 °C
Outlet temperature: t2 = 80 °C
Cooling air rate: Ac = 200 kg/h
Fines transport air: At = 500 kg/h
Transport air temperature tt = 60 °C
 
The values for operating parameters were estimated from product experience with respect to the required quality specification. The powder temperature is estimated to be 5°C below the outlet air temperature, fines recirculation ratio R = 0.5, radiation loss coefficient K = 3.0 kcal/ m2/h and dryer surface area 300 m2. The heat capacities of air and water vapour are taken from Equation 3.8 and 3.10 (ca1=0.245, ca2 = 0.241, caa = 0.24, cat = 0.241, cv1 = 0.463, cv2 = 0.45, cva = 0.444 and cvt = 0.448kcal/kg/°C). The product is whole milk with 28% fat, thus the heat capacity of solids, using values from Table 3.2. is:
 
cs = (28 * 0.5 + (100 - 28) * 0.3)/100 = 0.356 kcal/kg/°C
 
Calculation (according to equations [6,9], [6,7] and [6,39] through [6,46]:
 
DPR = 4000 * 48/95 = 2021.1 kg/h
DER = 4000 - 2021.1 = 1978.9 kg/h
Qev = 1978.9 * (597.3 + 0.45 * 80 - 60) = 1134530.5 kcal/h
Qpr = 2021.1 * (80 - 5 - 60) * (0.356 * 95 / 100 + (1 - 95 / 100)) = 11768.6 kcal/h
Qco = 200 / 1.01 * ((80 * 0.241 - 15 * 0.24) + * (80 * 0.45 - 15 * 0.444)) = 3163.0 kcal/h
Qtr = 500 / 1.01 * ((80 * 0.241 - 60 * 0.241) + 0.01 * (80 * 0.45 - 60 * 0.448)) = 2431.3 kcal/h
Qfi = 2021.1 * 0.5 *(80 - 5 - 60) * (0.356 * 95 / 100 +(1 - 95 / 100)) = 5884.3 kcal/h
Qrl = 300 * 3.0 * (80 - 15 - 20) = 40500.0 kcal/h
ΣQ = 1134530.5 + 11768.6 + 3163 + 2431.3 + 5884.3 + 40500 = 1198277.7 kcal/h
Adr = 1198277.7 / (200 * .245 - 80 * .241 + 0.01 * (200 * .463 - 80 * 0.45)) = 39565 kg/h
 
The above calculation can be simplified by neglecting the air moisture content and powder moisture and using for heat capacities of air and of water vapour constants 0.24 and 0.46 kcal/ kg/°C respectively:
 
Qev = 1978.9 * (597.3 + 0.46 * 80 - 60) = 1136113.7 kcal/h
Qpr = 2021.1 * 0.356 * (80 - 5 - 60) = 10792.4 kcal/h
Qco = 200 * 0.24 * (80 - 15) = 3120.0 kcal/h
Qtr = 500 * 0.24 * (80 - 60) = 2400.0 kcal/h
Qfi = 2021.1 * 0.356 * (80 - 5 - 60) = 5396.1 kcal/h
Qrl = 300 * 3.0 / (80 - 15 - 20) = 40500.0 kcal/h
ΣQ = 1198322.2 kcal/h
Adr = 1198322.2 / (0.24 * (200 - 80)) = 41608 kg/h
 
This comparison demonstrates that the simplified calculation results in more than 5% higher amount of air and emphasizes the importance of calculation on the enthalpy basis. The difference is even greater if the available ambient air has high humidity values. The absolute humidity of the exhaust air is:
[6,55]
Total exhaust air = 39565.4 + 200 + 500 + 1978.9 = 42244.3 kg/h
Exhaust air density Vexair and volume Vexair are then:
[6,56]
[6,57]
The dryer should have two main cyclones of cyclone constant 380 operating at a pressure drop of 150 mm WG. The cyclone diameter according to the equation [6.29] will be:
[6,58]

Table of contents

  1. 1.Introduction
  2. 2.Evaporation
    1. 2.1. Basic principles
    2. 2.2. Main components of the evaporator
    3. 2.2.1. Heat exchanger for preheating
    4. 2.2.1.1. Spiral-tube preheaters
    5. 2.2.1.2. Straight-tube preheaters
    6. 2.2.1.3. Preheaters to prevent growth of spore forming bacteria
    7. 2.2.1.3.1. Direct contact regenerative preheaters
    8. 2.2.1.3.2. Duplex preheating system
    9. 2.2.1.3.3. Preheating by direct steam injection
    10. 2.2.1.4. Other means to solve presence of spore forming bacteria
    11. 2.2.1.4.1. Mid-run cleaning
    12. 2.2.1.4.2. UHT treatment
    13. 2.2.2. Pasteurizing system including holding
    14. 2.2.2.1. Indirect pasteurization
    15. 2.2.2.2. Direct pasteurization
    16. 2.2.2.3. Holding tubes
    17. 2.2.3. Product distribution system
    18. 2.2.3.1. Dynamic distribution system
    19. 2.2.3.2. Static distribution system
    20. 2.2.4. Calandria(s) with boiling tubes
    21. 2.2.5. Separator
    22. 2.2.5.1. Separators with tangential vapour inlet
    23. 2.2.5.2. Wrap-around separator
    24. 2.2.6. Vapour recompression systems
    25. 2.2.6.1. Thermal Vapour Recompression – TVR
    26. 2.2.6.2. Mechanical Vapour Recompression - MVR
    27. 2.2.7. Condensation equipment
    28. 2.2.7.1. Mixing condenser
    29. 2.2.7.2. Surface condenser
    30. 2.2.8. Vacuum equipment
    31. 2.2.8.1. Vacuum pump
    32. 2.2.8.2. Steam jet vacuum unit
    33. 2.2.9. Flash coolers
    34. 2.2.10. Sealing water equipment
    35. 2.2.11. Cooling towers
    36. 2.3. Evaporator design parameters
    37. 2.3.1. Determination of heating surface
    38. 2.3.2. Heat transfer coefficient
    39. 2.3.3. Coverage coefficient
    40. 2.3.4. Boiling temperature
    41. 2.4. Evaporation parameters and its influrence on powder properties
    42. 2.4.1. Effect of pasteurization
    43. 2.4.1.1. Bacteriological requirements
    44. 2.4.1.2. Functional properties of dried products
    45. 2.4.1.2.1. Heat classified skim milk powders
    46. 2.4.1.2.2. High-Heat Heat-Stable milk powders
    47. 2.4.1.2.3. Keeping quality of whole milk powders
    48. 2.4.1.2.4. Coffee stability of whole milk powders
    49. 2.4.2. Concentrate properties
  3. 3.Fundamentals of spray drying
    1. 3.1. Principle and terms
    2. 3.1.1. Drying air characteristics
    3. 3.1.2. Terms and definitions
    4. 3.1.3. Psychrometric chart
    5. 3.2. Drying of milk droplets
    6. 3.2.1. Particle size distribution
    7. 3.2.2. Mean particle size
    8. 3.2.3. Droplet temperature and rate of drying
    9. 3.2.4. Particle volume and incorporation of air
    10. 3.3. Single-stage drying
    11. 3.4. Two-stage drying
    12. 3.5. Expansion of air bubbles during drying
    13. 3.6. Extended Two-stage drying
    14. 3.7. Fluid bed drying
  4. 4.Components of a spray drying installation
    1. 4.1. Drying chamber
    2. 4.2. Hot air supply system
    3. 4.2.1. Air supply fan
    4. 4.2.2. Air filters
    5. 4.2.3. Air heater
    6. 4.2.3.1. Indirect: Gas / Electricity
    7. 4.2.3.2. Direct heater
    8. 4.2.4. Air dispersers
    9. 4.3. Feed supply system
    10. 4.3.1. Feed tank
    11. 4.3.2. Feed pump
    12. 4.4. Concentrate heater
    13. 4.4.1. Filter
    14. 4.4.2. Homogenizer/High-pressure pump
    15. 4.4.3. Feed line
    16. 4.5. Atomizing device
    17. 4.5.1. Rotary wheel atomizer
    18. 4.5.2. Pressure nozzle atomizer
    19. 4.5.3. Two-fluid nozzle atomizer
    20. 4.6. Powder recovery system
    21. 4.6.1. Cyclone separator
    22. 4.6.2. Bag filter
    23. 4.6.3. Wet scrubber
    24. 4.6.4. Combinations
    25. 4.7. Fines return system
    26. 4.7.1. For wheel atomizer
    27. 4.7.2. For pressure nozzles
    28. 4.8. Powder after-treatment system
    29. 4.8.1. Pneumatic conveying system
    30. 4.8.2. Fluid bed system
    31. 4.8.3. Lecithin treatment system
    32. 4.8.4. Powder sieve
    33. 4.9. Final product conveying, storage and bagging-off system
    34. 4.10. Instrumentation and automation
  5. 5.Types of spray drying installations
    1. 5.1. Single stage systems
    2. 5.1.1. Spray dryers without any after-treatment system
    3. 5.1.2. Spray dryers with pneumatic conveying system
    4. 5.1.3. Spray dryers with cooling bed system
    5. 5.2. Two stage drying systems
    6. 5.2.1. Spray dryers with fluid bed after-drying systems
    7. 5.2.2. TALL FORM DRYER™
    8. 5.2.3. Spray dryers with Integrated Fluid Bed
    9. 5.3. Three stage drying systems
    10. 5.3.1. COMPACT DRYER™ type CDI (GEA Niro)
    11. 5.3.2. Multi Stage Dryer MSD™ type
    12. 5.3.3. Spray drying plant with Integrated Filters and Fluid Beds - IFD™
    13. 5.3.4. Multi Stage Dryer MSD™-PF
    14. 5.3.5. FILTERMAT™ (FMD) integrated belt dryer
    15. 5.4. Spray dryer with after-crystallization belt
    16. 5.5. TIXOTHERM™
    17. 5.6. Choosing a spray drying installation
  6. 6.Technical calculations
    1. 6.1. Evaporation and product output
    2. 6.2. Heating of atmospheric air
    3. 6.3. Mixing of two air stream
    4. 6.4. Dry air rate, water vapour rate and air density
    5. 6.5. Air velocity in ducts
    6. 6.6. Air flow measurements
    7. 6.7. Barometric distribution law
    8. 6.8. The heat balance of a spray dryer
  7. 7.Principles of industrial production
    1. 7.1. Commissioning of a new plant
    2. 7.2. Causes for trouble-shooting
    3. 7.3. Production documentation
    4. 7.3.1. Production log sheets
    5. 7.3.2. General maintenance log book
    6. 7.3.3. Product quality specification
    7. 7.3.4. Operational parameter specification
    8. 7.4. Product quality control
    9. 7.4.1. Process quality control
    10. 7.4.2. Final quality control
  8. 8.Dried milk products
    1. 8.1. Regular milk powders
    2. 8.1.1. Regular skim milk powder
    3. 8.1.2. Regular whole milk powder
    4. 8.1.3. Whole milk powder with high free fat content
    5. 8.1.4. Butter milk powder
    6. 8.1.4.1. Sweet butter milk powder
    7. 8.1.4.2. Acid butter milk powder
    8. 8.1.5. Fat filled milk powder
    9. 8.2. Agglomerated milk powders
    10. 8.2.1. Agglomerated skim milk powder
    11. 8.2.2. Agglomerated whole milk powder
    12. 8.2.3. Instant whole milk powder
    13. 8.2.4. Agglomerated fat filled milk powder
    14. 8.2.5. Instant fat filled milk powder
    15. 8.3. Whey and whey related products
    16. 8.3.1. Ordinary sweet whey powder
    17. 8.3.2. Ordinary acid whey powder
    18. 8.3.3. Non-caking sweet whey powder
    19. 8.3.4. Non-caking acid whey powder
    20. 8.3.5. Fat filled whey powder
    21. 8.3.6. Hydrolysed whey powder
    22. 8.3.7. Whey protein powder
    23. 8.3.8. Permeate powders
    24. 8.3.9. Mother liquor
    25. 8.4. Other Dried Milk Products
    26. 8.5. Baby food
    27. 8.6. Caseinate powder
    28. 8.6.1. Coffee whitener
    29. 8.6.2. Cocoa-milk-sugar powder
    30. 8.6.3. Cheese powder
    31. 8.6.4. Butter powder
  9. 9.The composition and properties of milk
    1. 9.1. Raw milk quality
    2. 9.2. Milk composition
    3. 9.3. Components of milk solids
    4. 9.3.1. Milk proteins
    5. 9.3.2. Milk fat
    6. 9.3.3. Milk sugar
    7. 9.3.4. Minerals of milk
    8. 9.4. Physical properties of milk
    9. 9.4.1. Viscosity
    10. 9.4.2. Density
    11. 9.4.3. Boiling point
    12. 9.4.4. Acidity
    13. 9.4.5. Redox potential
    14. 9.4.6. Crystallization of lactose
    15. 9.4.7. Water activity
    16. 9.4.8. Stickiness and glass transition
  10. 10.Achieving product properties
    1. 10.1. Moisture content
    2. 10.2. Insolubility index
    3. 10.3. Bulk density, particle density, occluded air
    4. 10.4. Agglomeration
    5. 10.5. Flowability
    6. 10.6. Free fat content
    7. 10.7. Instant properties
    8. 10.7.1. Wettability
    9. 10.7.2. Dispersibility
    10. 10.7.3. Sludge
    11. 10.7.4. Heat stability
    12. 10.7.5. Slowly dispersible particles
    13. 10.7.6. Hot water test and coffee test
    14. 10.7.7. White Flecks Number (WFN)
    15. 10.8. Hygroscopicity, sticking and caking properties
    16. 10.9. Whey Protein Nitrogen Index (WPNI)
    17. 10.10. Shelf life
  11. 11.Analytical methods
    1. 11.1. Moisture content
    2. 11.1.1. Standard oven drying method (IDF Standard No.26-1964 [32])
    3. 11.1.2. Free moisture
    4. 11.1.3. Total moisture
    5. 11.1.4. Water of crystallization
    6. 11.2. Insolubility index
    7. 11.3. Bulk density
    8. 11.4. Particle density
    9. 11.5. Scorched particles
    10. 11.6. Wettability
    11. 11.7. Dispersibility
    12. 11.8. Other methods for determination of instant properties
    13. 11.8.1. Sludge
    14. 11.8.2. Slowly dispersible particles
    15. 11.8.3. Hot water sediment
    16. 11.8.4. Coffee test
    17. 11.8.5. White flecks number
    18. 11.9. Total fat content
    19. 11.10. Free fat content
    20. 11.11. Particle size distribution
    21. 11.12. Mechanical stability
    22. 11.13. Hygroscopicity
    23. 11.14. Degree of caking
    24. 11.15. Total lactose and α-lactose content
    25. 11.16. Titratable acidity
    26. 11.17. Whey Protein Nitrogen Index (WPNI)
    27. 11.18. Flowability (GEA Niro [31])
    28. 11.19. Lecithin content
    29. 11.20. Analytical methods for milk concentrates
    30. 11.20.1. Total solids
    31. 11.20.2. Insolubility index
    32. 11.20.3. Viscosity
    33. 11.20.4. Degree of crystallization
  12. 12.Troubleshooting operations
    1. 12.1. Lack of capacity
    2. 12.2. Product quality
    3. 12.3. Deposits in the system
    4. 12.4. Fire precaution
    5. 12.5. Principles of good manufacturing practice
    6. 12.6. The use of computer for quality control and trouble-shooting
  13. References
Reference: Schlünder,E.U.:Dissertation Techn.Hochschule Darmstadt D 17, 1962.