Download

Industrial Energy Savings
Opportunities for Food
Processing
Presented by:
Nosh Makujina
Cascade Energy

Agenda
• Energy use breakdowns
• Refrigeration energy savings
opportunities
• Lighting energy savings opportunities
• Compressed air energy savings
opportunities
• Pumping system energy savings
opportunities
• Case studies
2

Major Food Processor & Cold
Storage Energy Users
• Electricity
– Refrigeration
– Compressed Air
– Lighting
– Pumping & Fans/Blowers
– Battery Chargers
– Nitrogen Generation / Scrubbers
– HVAC
• Natural Gas
– Boilers / Steam
• Cookers/peelers
• Blanchers
• CIP / Washdown
• Pasteurizers
– Dryers
– Fryers
– HVAC
3

Sample Energy Source
Breakdowns
Facility Type Electricity Nat. Gas
Potato Processing 19% 81%
Dairy 54% 46%
Vegetable Processing 70% 30%
Refrigerated Warehouses >95%

Sample Electricity Use
Breakdowns
Refrigeration
Lighting
Compressed Air
Nitrogen/Scrubbers
Pumps/Fans
Miscellaneous
Facility Type
Refrigerated Warehouse 65% 15% 20%
Fruit Storage 75% 15% 10%
Dairy 60% 9% 15% 10% 6%
Potato Processing 50% 8% 3% 24% 15%
5

Sample Industrial Refrigeration
Loads
Freeze Tunnel - Vegetables
Blast Freezer – Meat & Fruit
Freezer or Cooler
Refrigerated Warehouse
Popsicle Machine
6
Spiral Freezer – Meat and
Prepared Foods
Scraped-Surface HX
Ice Cream & Puree
Plate HX
Ice Cream and
Prepared Foods
Flake Ice
Maker

Major Refrigeration
Components
Evaporator Coils
Condensers
7
Compressors

8
Refrigeration Controls

Refrigeration Savings Potential
• Retrofit projects
– Based on control trend data, data
loggers or engine room logs
– 10% to 30%+ savings
• New construction projects
– Based on projected performance of
building and processes
– 20% to 40%+ savings
9

Introduction to Efficiency
1. Reducing System Lift
2. Improving Part Load Performance
3. Equipment-Specific Upgrades
4. System Design
5. Reduction of Refrigeration Loads
6. O&M and Commissioning
10

Reducing System Lift
• Raise Suction: More Capacity
(Ton of Refrigeration, or TR)
• Lower Discharge: Less Power
(Brake Horsepower, or BHP)
• Reduce “Lift”: Higher
Efficiency (BHP/TR)
11

Increasing Suction Pressure
• Rule of thumb savings: 2%
compressor savings per degree F
increase in suction
• Common approaches
– Simply raise set-point
– Reduce pressure drop or other
bottlenecks
– Larger evaporators or heat
exchangers
– Correctly match suctions to loads
12

Reducing Discharge Pressure
• Rule of thumb savings: 1.5%
compressor savings per degree F
reduction in condensing
temperature
• Common approaches
– Larger condensers
– Reducing minimum condensing
pressure requirements
13

Improving Part Load Performance – Fan &
Compressor VFDs
Evaporator and Condenser Fan VFDs
Compressor VFD
with Air Conditioner
14
Compressor Inverter-Rated Motor

Evaporator Equipment
Upgrades
TR/HP
Coil Efficiency vs Face Velocity
7.0
6.5
6.0
5.5
More Efficient / Larger Evaporator Coils
5.0
High Efficiency Fan Blades
4.5
4.0
550 600 650 700 750
Face Velocity (fpm)
15
Defrost Float Drainers
Evaporator Defrost Hoods & Socks

Compressor Equipment
Upgrades
Inefficient Liquid Injection Cooling…….
…..Efficient Thermosiphon Cooling
Compound Compressor Selection
16
Screw Compressor Economizers

MBH per Fan/Pump HP
Condenser Equipment Upgrades
Evaporative Condenser Efficiency Comparison
400
350
300
250
200
150
100
Forced Draft - Axial
Induced Draft - Axial
50
Forced Draft - Centrifugal
0
- 5,000 10,000 15,000 20,000 25,000 30,000
Nominal Heat Rejection - MBH
High-Performance
Water Spray Nozzles
High-Efficiency Condenser Selection
(High Btu Rejection per Horsepower)
17

Refrigeration Controls Upgrade
Old Compressor Control Panel
Modern Compressor Microprocessor Panels
Old Pressure Switch Control
Modern Computer Control
18

Reduced Refrigeration Loads
Increased Insulation Levels
Freezer & Cooler Door Upgrades
19

O&M Evaporator Coils
• Clean evaporator coils regularly.
• Rebuild leaky or inoperable valves.
• Calibrate temperature probes &
regulators.
20

21
Calibrate Pressure Regulators

Condenser O&M
• Clean nozzles and
strainers
• Clean tubes
• Clean drift eliminators
• Check and set water
header pressure
• Service belt drives
• Prevent recirculation and
saturation
• Treat condenser water
• Check and purge noncondensables
• Deal with poor
environment
22

23
Plugged Water Distribution

Broken Distribution System
This condenser is only 8 months old!
24

Water Treatment is Critical
Sample of Critical Condenser Tube Scaling
25

Lighting
• Reducing lighting energy reduces space
refrigeration load.
• Reduce lighting connected load.
– Pulse-start metal halide
– T8 or T5 fluorescent
• Insulated fixtures for freezers
• Implement advanced controls.
– Motion detectors
• Bi-level for metal halide or HPS
• Partial or full fluorescent cycling
26

Lighting
Retrofit Lighting Examples (ambient
environments)
• Incandescent to compact fluorescent
• T12 fluorescent to T8 fluorescent
• HID to Fluorescent
• Old T8 to New T8
• Reduced Wattage T8s
• Toggle switch to occupancy sensor
• Breakers to relays and timeclocks
27

Lighting
28
Freezer Lighting Example
• Existing lights 400 W MH HID (458
Watts)
• Replacement lights, 6 lamp T5HO with
occupancy sensor (352 Watts)
• Results in 25% less power with 10%
increase in Lumens.
• Does not include occupancy sensor
savings

29
Compressed Air – The Energy Hog

Why Use Compressed Air:
• Safe (relatively) – can be used in
wet/explosive environments
• Compressed air powered equipment
is often less expensive
• Convenient – pipe, tubing, hose
30

Why NOT to use Compressed Air:
• Very inefficient
– 80%+ of compressor power is rejected
as heat
– 15% or less of input energy is available
for useful work
– To get 1 HP of useful work, 7-8 HP of
compressor work is required
– This is at full load. At part load the
story is even worse…
31

Power
Modulating Control – Common
• Modulation = choke
off air flow to
compressor inlet to
reduce air
production
• Lowest first cost
• Little or no tank
capacity required
• Terrible part load,
70% power at 0%
capacity
Modulating Part Load
100%
75%
50%
25%
0%
0% 25% 50% 75% 100%
Capacity
32

Typical Food Processing Systems
• Compressors
– Several oil flooded screws
– Modulating controls on screws
– Reciprocating compressors for small
users
– Minimal tank capacity
– No control system, manual on/off
• Dryers
– Usually refrigerated, some desiccant
33

Typical Food Processing Systems
34
• Header Pressure – 100 to110 psig
• Piping – May be undersized due to plant
growth
• Air Users
– Leaks – 15% to 50% of demand
– Clean Up
– Open Air Blows
– Pumps & Motors
– Maintenance Tools
– Sorting and Packaging Equipment
– Valves and Cylinders

General Compressed Air Efficiency
Opportunities
• Improve compressor part load
efficiency
• Reduce compressor operating pressure
• Reduce compressed air loads
• Improve dryer efficiency
35

Saving $$ With Compressed Air
• Efficient Part Load Controls
– First Method: Load/Unload
system
• Load/unload controls: May
already be installed
• Tanks: Need large volume to
pack with air during loaded
operation, and draw air from
during unloaded operation.
Absolutely necessary for an
efficient system!!!
• Flow controller Valve: A fancy
pressure regulator. Holds
plant air pressure steady while
tank pressure cycles up and
down. Not required, but a
good idea.
36

kW
PSIG
Typical Load/Unload Operation
100
Tank Pressure (Blue) Header Pressure (Pink)
95
90
85
80
75
70
15:05 15:15 15:25 15:35 15:45
120
Compressor Power
100
80
60
40
20
0
15:05 15:15 15:25 15:35 15:45
37

Power
Variable Speed Compressors
– Variable frequency drive (VFD) adjusts compressor speed
to match pressure setpoint
– Made by every major compressor supplier
– Can put VFDs on some existing compressors
– Much less tank volume required
– First cost is 20% to 40% more than standard compressor
– Part load efficiency is very good
100%
Variable Speed Part Load
75%
50%
25%
0%
0% 25% 50% 75% 100%
Capacity
38

Efficient Part Load Controls
Continued…
• Multiple compressor systems may need a
control system to start/stop compressors.
• These are custom solutions – one size
does not fit all.
– If you have compressors that unload well,
it may be best to install load/unload
system.
– If you are buying a new compressor
anyway, it may be best to upgrade to a
variable speed compressor.
39

Once Part Load Efficiency is Good…
40
• Reducing Air Demand = Big Energy Savings
– Leak reduction
– No-air-loss drains on tanks & dryers
– Engineered nozzles on blows. No tubing blows!
– Convert to non-air devices
– Take low pressure users off compressed air
system, install blower systems where possible
– Dryer air losses
• Get away from heatless desiccant dryers (15% purge)
• Convert to heated desiccant dryers (7% purge) or
better yet…
• Convert to refrigerated dryers (0% purge). Cheaper to
heat trace and insulate outdoor pipe than supply purge
losses.
• Install purge controls on trim desiccant dryers.

Improve Full Load Efficiency by:
• Reducing Pressure Settings
– Almost all devices will operate at 60 psig
with adequate local air storage
– Upgrade users
• Remote tanks, near users
• Dedicated tanks, after regulators
– Fix piping bottlenecks
– Aim for 80 to 90 psig header pressure
– Saves compressor power (.5% per psi)
– Lower header pressure reduces air demand
saving even more power
41

System Designer Notes
• Avoid air consuming equipment when possible
• Don’t purchase equipment which specifies >80 psig
supply requirement
• Size piping generously, assume large plant growth
• Design for refrigerated drying, 40°F dewpoint
• Get an air audit prior to purchasing a new
compressor. This is an ideal time to do upgrades and
select ideal equipment.
• 70% of the total life cycle cost for a typical air
compressor is energy. First cost and maintenance
are almost insignificant in comparison.
42

Pumps
• Things to look for:
• Throttle valve-controlled systems
• Bypass (recirculation) line normally open
• Multiple parallel pump system with same
number of pumps always operating
• Constant pump operation in a batch
environment
• Pump not used for different function than
originally intended
43

44
Throttled Pump Discharge

Constant Flow Systems
• Solutions for inefficient systems with
constant flow requirements:
• Trim Pump Impeller: Low cost solution
where only a small change in flow is
necessary
• New Pump: Medium cost solution where a
large change in flow is necessary
• VFD Pump Control: High cost solution
where a new pump is not possible
45

Variable Flow Systems
• Ideal for “closed loop” applications
where there is no net elevation gain
• VFD control of pumps based on
maintaining critical pressure in system
• May need to replace bypass lines with
2-way valves to create variable flow
situation
46

Case Studies
• Compressed Air
– Controls
– Application
• Refrigeration
– Central Control System
– Evaporator Fan VFD’s
47

Case Studies Compressed Air
• Convert the air compressors to
load/unload control
• Disable the throttling feature of the
compressors
– Add 3,000 gallons of air tank capacity
• Replace undersized filters
48

Case Studies Compressed Air
Load/Unload Compressors
• Project Economics
• Annual energy savings: 100,000
kWh/yr
• Annual cost savings: $4,000
• Implementation cost: $12,600
• Energy Trust incentive: $6,300
• State tax credit: $3,200
• Final cost with incentives: $3,100
• Simple Payback:
0.8 yrs
49

Case Studies Compressed Air
• Convert from compressed air injection
aeration of wastewater to mechanical
aeration
• Eliminate use of compressed air
• Eliminate circulations pumps (30 hp)
• Install a VFD controlled mechanical mixer
(30 hp) that adjusts speed to maintain
dissolved oxygen levels
50

Case Studies Compressed Air
Wastewater Aeration
• Project Economics
• Annual energy savings: 240,000
kWh/yr
• Annual cost savings: $7,700
• Implementation cost: $70,000
• Utility incentive: $35,000
• State tax credit:
$17,850
• Final cost with incentives: $17,150
• Simple Payback:
2.3 yrs
51

Case Studies Refrigeration
• Install central control system
– Properly stage compressors
– Increase suction pressure from tighter
controls
– Reduce minimum head pressure from
tighter controls
– Manage condenser VFDs
52

Case Studies Refrigeration
Project Economics
• Annual energy savings 2,200,000
kWh/yr
• Annual cost savings $105,000
• Implementation Cost $320,000
• Utility Incentive (50%) $160,000
• Final Cost with incentives $160,000
• Simple Payback
1.5 yrs
53

Case Studies Fruit Storage
Evaporator Fan VFD’s
Project Economics
• Annual energy savings 1,300,000 kWh/yr
• Annual cost savings $44,000
• Implementation Cost $117,000
• Utility Incentive (50%) $58,000
• Final Cost with incentives $58,000
• Simple Payback
1.3 yrs
54