mechanical, electrical, control/automation ...€¦ · morris sallick industrial supplies, inc....

Morris Sallick Industrial Supplies, Inc. Mechanical, Electrical, Control/Automation & Instrumentation Process Engineering

HUMIDITY & DEWPOINT CONTROL

Packaging – Avoids clogged equipment – Reduces cleaning frequency – Allows fast wrapping with

polypropylene

Pan Coating – Improves surface finish – Speeds water-based drying – Eliminates picking & sticking

Hygroscopic Material Conveying / Storage – Eliminates Clogging and Sticking – Eliminates Product Waste – Improves Product Consistency

Spray Drying/Instantizing – No clogs in product collectors – Allows smaller fluid beds – Increases throughput of towers

Low-Temperature Drying – Improves product quality – Fast drying at low temperature

Enrobers – Eliminates skirting – Eliminates condensation – Improves sanitation



Refrigerated Warehouses – Eliminates fog / condensation – Eliminates slippery floors – Improves worker safety – Prevent mold growth.

Meat Processing – Eliminates condensation dripping onto

product. – Reduces pull down time after wash

down = increased production time. – Improves worker comfort.

Loading Docks – Extends cooler defrost cycle – Reduces labor with no chipping ice

off floors, doors & racks. – Shift latent load to lower cost utility

(natural gas).

Spiral Freezers – Eliminates conveyor defrost – Eliminates floor icing – Reduce ice buildup on evaporator

coils – Improves refrigeration COP – Eliminates ice on downstream

weighing machinery



Air is circulated across a cold coil and cooled to saturation

Further cooling condenses moisture from the air stream

Dew point reduction is limited by minimum practical coil temperatures

Air is delivered at saturated conditions



70°F 56 gr/lb

25 °F 19 gr/lb

FOG FROST


HUMIDITY & DEWPOINT CONTROL Hygroscopic materials don’t stick

together Products flow freely through

conveyers and hoppers Improved product quality with

finished product (no clogging) Eliminates condensation dropping

onto product - hygiene risk Prevents costly shutdowns,

production interruptions and product loss

Return to production quicker – Product clogging often results in

downtime. – DH helps dry cleaned equipment.



Silo Conveying Mixing and blending Drying- fluid bed, spray

tower Coating Cooling tunnels Freezing Storage


HUMIDITY & DEWPOINT CONTROL Storage – Silo

Removes condensation

Prevents mold growth

Stops caking

Dry air

Prevention of clogging

Elimination of condensation

Prevents mold growth

Sizing

•Typically .5 AC/H for the volume of the silo (once through system)

•Once Through System



• As air is compressed and the air volume decreases

• The moisture content of the air remains the same, causing the dew point to shift and increase

• High humidity will be absorbed by product, or can stick to line especially on cold spots.

Desiccant Unit

Filter

Silo

Valve

Vacuum Pump

Mixing Vessel

Pneumatic Conveying


HUMIDITY & DEWPOINT CONTROL Storage

• Reduces waste in storage

• Prevents sticking and lumpy material

• Prevents mold

• Eliminates condensation (ice)

• Prolongs shelf-life and quality


HUMIDITY & DEWPOINT CONTROL 10% RH Room - Typical Schematic

Bypass only at low load

300 cfm leaves the roomthrough cracks and doors

F E

D C A

BDifferentialpressurecontrol

P

G

LocationAirflow( cfm )

Temp( ° F )

Moisture( gr/lb )

A 800 91 147B 3000 70 11C 3800 66 20D 3800 86 4E 3800 86 4F 3800 60 4G 500 70 11

H

F

F

CC

T

C

T

F

C

Room control for humidity and temperature

Face and bypass for tight humidity control


HUMIDITY & DEWPOINT CONTROL Spray Tower Problems

• Production rate varies by season

• Drying time too long

• Inconsistent quality of the powder

• Production stops • Product scrap • Lack of flexibility


HUMIDITY & DEWPOINT CONTROL Spray Dryers, Approach

• Using desiccant technology to dry the outside air required for the process.

• Provide a consistent low dew point.

• Desiccant wheel removes moisture while also heating the process air (energy savings)



Typical Production Losses Related to Moisture in the Air

0

10

20

30

40

50

60

70

80

90

January February March April May June July August September October November December

Hu

mid

ity

Gr/

Lb

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

% lo

st o

f p

rod

uct

ion

Minimum 20% of the production is lost each year



Actual Example of Drying Time Summer vs. Winter

• Batch consists of 4 cycles • Summer cycle 110 min. • Winter cycle 90 min. • Prep is down time between

cycles • Winter batch 20% faster

processing time

0

100

200

300

400

500

600

Summer Winter

DryingPrepTotal



• Production rate varies by season • Drying time to long • Consistant quality of the powder • Non predictable parameters • Production stops • Product scrap • Lack of flexibility

Fluid Bed


HUMIDITY & DEWPOINT CONTROL Typical Process Freezer

(Lower Level)

Suction Side Of Freezer Product Flow

Moisture Leakage

Ice Buildup on Evaporator Coils

Packaging Area (Upper Level)

Product Flow

Packaging Area


HUMIDITY & DEWPOINT CONTROL Design conditions in process freezer applications without dehumidification



Makeup Air System with Tunnels Condition air at

product entrance and exit to remove infiltration load


HUMIDITY & DEWPOINT CONTROL Air System with Vestibule

Condition air at product entrance and exit to remove infiltration load



• Reduction in defrost cycles in freezer

• Reduction in ice on inlets and outlets of conveyors

• More throughput • Coils working more efficiently • Able to stay in production



Freezer Storage Issues

• Ice forms at all openings • To hold 32°F and below

temperatures, coils must supply below freezing temperatures

• Product drying is not allowed • Large infiltration load (doors)


HUMIDITY & DEWPOINT CONTROL Loading Docks

Humidity Issues • Ice Build-up On Freezer Ceiling

and Around Door Frames • Fogging, Wet Floors,

Condensation and Moisture • Mold/Mildew • Energy Management and

Facility Productivity • Worker Comfort & Safety

• Loading dock doors and seals (assuming dock doors remain shut until truck is backed into place)

• Conveyers and open areas underneath loading docks

In these applications the primary source of moisture is a result of infiltration from:


HUMIDITY & DEWPOINT CONTROL Dehumidification System Flow Diagram



Free Flowing Powders



Desiccant enhanced dehumidifier doesn`t need to cool to as low a temperature, so it saves significant energy over conventional systems

Desiccant enhanced dehumidifier

Cooling-Reheat dehumidifiers Require 30% to 40% additional

cooling to achieve same dew point

mechanical, electrical, control/automation ...€¦ · morris sallick industrial supplies, inc....

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