Transcript 3 - Systecore Inc.

Engineering Presentation
Variable Speed Pumping in Hydronic Systems
• Why use VFD or VSD Pumps?
• What are they and how do they work
• Back to the basics – reading constant speed curves
• Basics – Understanding trimmed impeller curves
• Basics – Understanding multiple speed curves
• Basics – Understanding VFD curves
• Applications – when and where to use VFD’s
• Questions
1
It is very often a 98% efficient boiler is
placed in a 20% efficient system resulting
in little to no savings in energy
consumption.
 We suggest putting your energy toward
balancing production (boilers) with
consumption (Air Handling Units, fin tube
radiation, etc) by providing the proper
distribution (pumping and balance).

ECM technology with wire to water
savings up to 80%, at very effective cost
points with Variable Speed, ECM motor
and system control built into the pump
itself.
 These pumps are the one stop solution to
system efficiency, correcting the system
and distribution efficiency with boiler
efficiency.
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Patterson Pumps has excelled in their design and
efficiencies offering better design point operating
efficiency; most often offering a step down in HP
for identical flow and head applications resulting
in higher wire to water efficiency in addition to
improving the system efficiency.
We have paired Premium Efficient Pumps with
Premium Efficient Motors with the Cloud line of
Variable Speed Drives.
Train
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Consumption
Production
Distribution
Variable Speed Pumping
Variable Volume Pumping
Cv’s / GPM of Coil or slightly greater 1#
Coils etc / Importance of Flow Limiting
Cv =gpm/delta P square root
For the coldest day of the year ~2 % of the total operating period
Transition period (coldest design day)
But how is the system working during the remaining 98 % of the operating
period?
Transition period
Transition period with standard Pumps
Oversizing causes by worst case situation
H = Pumping Head HPU
Q = Flowrate VPU
H
Transition period
Increase of the pumping head /
system noises possible
Unnecessary energy consumption
Duty point on coldest day of the year
Q
200 gpm = 2,000,000 Btu/Hr
500 x 20
300 gpm = 2,000,000 Btu/Hr
500 x 15
400 gpm = 2,000,000 Btu/Hr
500 x 10
Checking the system Delta T can suggest the system
Load
Checking the Boiler Delta T vs gas consumption gives
the real efficiency.
System Curve vs the Pump curve.
Variable Speed Pumping in Hydronic Systems
Why use VFD’s?
Global Studies Carried out by the European Commission
• Pumping systems account for 22% of the world’s electrical power demand
• Air Compressors 18%, Fans 16%, Cooling Compressors 7%, Other equipment 37%
• In some industrial plants pumps account for over 50% of the electrical load
• Rotodynamic (centrifugal) pumps account for 73% of all pumps
• Positive displacement (usually piston or screw types) account for 27%
• Over 95% of all pumps are oversized due to multiple butt covering!
• Up to 90% energy savings can be achieved using proper VFD techniques
• The pump can run closer to it’s Best Efficiency Point more frequently
The result of the effect of the Affinity Law is if we can operate a
125 Hp pump at half it’s speed and maintain the desired result of
it’s overall function it consumes only 5 Hp!
Pumps save electrical energy by
properly applying them, check the
HP of 200 gpm @ 45’ vs the HP of
200 gpm @ 12’.
This is really nice.
Now check out the Boiler operating
at 30% vs. the Boiler operating at 85
– 95% Efficient.
Really Really REALLY NICE Savings.
Variable Speed Pumping
Why use VFD’s?
• Impeller hydraulic forces are reduced with the square of the speed change
• Bearing life is proportional to the SEVENTH power of the speed change
• Longer seal life
• Less vibration and flow harmonics
• Lower cycling (more continual flow rates)
• Lower flow velocities
• Better air removal
• Longer glycol life
• Lower friction loss
• Quieter systems
• No need for energy hogs
• Pressure compensated by-pass valves
• Wild loop unit heaters
• Longer accessory life (zone valves, expansion tanks etc – soft starting)
Variable Speed Pumping
Why use VFD’s? Life Cycle Costs!
LCC = Cic + Cin + Ce + Co + Cm + Cs
• Cic – Purchasing cost (total can be less with VFD – ie: no bypass)
• Cin – Installation and commissioning cost (can be less with VFD)
• Ce – Lifetime energy cost (high savings with VFD)
• Co – Operation cost (labour the same)
• Cm – Maintenance cost (lower with VFD)
• Cs – Cost of lost production (lower with VFD – longer equipment life)
Properly applied VFD equipment can produce investment paybacks less than 2 years!
Basic Heat Theory – the Facts!
Is Flow Important in Hot Water Heating or Cooling?
Heat always moves from high temperature to low
temperature areas. Without temperature differential
there is no heat movement!
Remember – Heat takes the path of least resistance (least
insulation) – it does not rise. Hot air rises!
What is a BTU? It’s the amount of energy it takes to raise
one pound of water one degree F.
One Calculation to determine flow!
BTU = 500 (constant) x Usgpm x ΔT Temp Diff

Heating fluid standard is 20 degree ΔT
◦ Today with Energy Conservation this will vary.
◦ Heating systems 20 – 40 is standard, and
engineers tend to use boiler efficiency
standards where higher ΔT relates to higher
efficiency.
◦ Higher ΔT relates to lower flows and lower
pumping cost and lower distribution cost.

Cooling fluid standard is 10 degree ΔT

You have to watch for humidification issues.
ΔT review
1,000,000 Btu/Hr
1,000,000 Btu/Hr
100gpm x 500 x 20
 500 x 20 = 10,000
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500 constant for
water
50gpm x 500 x 40
 500 x 40 = 20,000

ΔT and outlet
temperature can
make anything
work
GPM relates to ΔT
GPM = BTU/HR
500 x ΔT
1,000 #/hr =
1 #/hr
1,000,000 Btu/Hr
=
1,000 Btu/Hr
1 ton = 12000 Btu/Hr
Formula’s
Heating Basics – Pump Sizing
What’s the head, capacity, voltage, pipe size & type, and overall application?
You need to know… FLOW – based on heat transfer (the Train)
1. BTU output of the boiler(s) for the primary pump(s) and loop loads for secondary
pump(s)
2. Design temperature differential (ΔT delta T) – dependant on application, local
climate etc
3. Calculate flow based on laws of thermodynamics (definition of a BTU)
Example: 250,000 BTU/Hr = 500 (constant) x 25 USGPM x 20 deg F
Calculate: Flow for 300,000 BTU/hr @ 20 deg F design differential?
30 Usgpm
Calculate: Flow for 100,000 BTU.hr @ 15 deg F differential?
13.3333 USGPM
Calculate: How many BTU’s will 80 USGPM transfer @ 40 deg F?
1,600,000 BTU or 1.6 MBH!
System Friction Loss (Head)
Is it a Pump or a Circulator?
Head H Ft
only one
thermostatic
Both
thermostatic
valves
valve
is
open
are open
intersecting
point = new
operation point
Flow Q USGPM
What to do with excess head
Typical Pumped Primary (Constant Speed Circulator)
Zone Valved Secondary
What to do with excess head
Constant Speed Circulator
Set point of pressure
bypass valve
Safety Margin When Calculating Piping
Oversizing caused by friction loss safety factors
planned piping duty curve
planned operating point
Curve A
actual piping duty curve
A
B
Curve B
actual operating point
DH
corrected operating point
C
Flowrate Q
Flow velocity v
DH = Safety margin when
A
B
Power
saving DP
C
Flowrate Q
calculating piping
means ~ 30% less
current consumed
Adjustment of the Pumping Capacity
Trimming Impellers?
Why Not?
24
50%
• Decreases Pump Efficiency
60%
70%
• One Way Trip
75%
20
79%
75%
16
70%
H.[FT]
12
8
4
10
20
30
40
50
60
70
80
90
100 110 120 130 140
US.gpm
Adjustment of the Pumping Capacity
Changing the speed – manual multiple speed
n1
H1
n2

Q1

H1

P1
Pumping Head H Ft
H2
Q2 Q1
Volume Flow Q USGPM
Q2
H2
P2
=
n1
n2
2
=
()

()
n1
n2
n1
n2
3
Adjustment of the Pumping Capacity
Changing the speed – the VFD way!
Pumping Head H %
100
93
81
64
49
36
25
1,0 • n
0,9 • n
0,8 • n
speed at 60 Hz
0,7 • n
0,6 • n
speed at 50 Hz
0,5 • n
speed at
approx. 40 Hz
0,4 • n
Volume Flow Q USGPM
Speed Control
Electronic continuous speed control (Constant Pressure)
◦ Automatic differential pressure control
1. The sensor determined the
actual pumping head. (actual
value)
nmax
2
Pumping Head H Ft
H2
H1
3
Q1
non-regulated pump
1
Q2
Volume Flow Q USGPM
2. The electronic discerned
the difference between the set
value (point 1) and the actual
value. (point 2)
3. The controller reduced the
speed and moves the
pumping head at the actual
value now. (point 3)
Speed Control Strategies
Electronic continuous speed control
◦ control modes
 ∆p-c
 differential pressure constant
 ∆p-v
 differential pressure variable (max head is
twice min head)
 ∆p-T
 temperature guided differential pressure
control
 ∆p-cv
 combination from differential pressure constant
(second and third area of characteristic) and
differential pressure variable (first area of characteristics)
◦ Operation modes
 Automatic  night setback (let down function)
 manual regulator
 DDC (Direct Digital Control)
Speed Control Comparisons
Comparison of the power consumption
power draw P1 W
max.-characteristic (non-regulated)
Dp constant
Dp variable
volume flow Q m³/h
“Delta PC” vs “Delta PV” ???
Delta PC or Constant Pressure (differential)
Delta PV or Pressure Variant (max head twice min)
H
Δpc
Saves energy, because the load-controlled
pump adjusts to system changes
Δpv
Q
Speed Control Methods
∆p-c  differential pressure constant
◦ Constant Pressure Differential Across
the Pump (H
)
◦ If the inlet pressure consistant (pump
away from the tank) this operates like
a pressure setpoint pump
set value
◦ Excellent in low friction loss systems
(flat friction loss curves)
◦ Independent of the number of the
opened thermostatic valves
Speed Control Method
Pumping Head H Ft
∆p-c  differential pressure constant
nmax
2
ncontrolled
3
Hset value
Dp-c
1
∆p-c
Hset value-min
Volume Flow Q USGPM
Typical Heating Pipe System with Dp-c Pump Control
2m
2m
H
[m]
4
2m
3
Δp-c-duty curve
2
2m
1
0,12
0,03
0,5 m
0,3
0
0
2,03
2,12
2,5
2,3
2,0 m
0
2
1
4 m3/h
3
1
2
3
4
Q [m3/h]
Speed Control Methods
∆p-v  differential pressure variable
◦ The maintained differential pressure-set
value of the pump is changing linear
between H and ½ H .
set value
set value
◦ Used in high friction loss systems with steep
friction loss curves
◦ The required differential pressure decreases
rapidly with less flow
Speed Control Methods
Pumping Head H Ft
∆p-v  differential pressure variable
Hset value
nmax
2
ncontrolled
1
3
½ Hset value
Hset value-min
Volume Flow Q USGPM
Typical Heating Pipe System with Dp-v Pump Control
2m
2m
H
[m]
Δp-c-duty curve
4
2m
3
2
2m
1,1
0,5
0,1
2m
1
0
0
2,1
3,1
2,5
4m
2,0
0
4 m3/h
3
2
1
1
2
3
4
Q [m3/h]
VFD Pump Applications – Things to Consider
• Type of Boiler
• Low mass boilers might not like low flows
•Heat Exchangers Laminar Flows
• Flow Switch Operation
• Paddle type flow switches might not activate
• Requires a change to control (setpoint or differential)
• Pressure
• Flow
• Temperature
• Level
•No change, not a VFD application
•Three Way Valves / Temperature or Pressure?
• Simplicity and Reliability of Equipment
Energy Rebate Template - Custom
Template A -- (Tertiary Coil/Unit Pumps)
Before Retrofit
The existing pump _Taco Model CC250C, 5.5, A4B2C1TL, _75_gpm @ _25_’tdh,
Supply _var_F, Return _+4_F 4∆T
1.0_hp _460_Voltage, _3_Phase, Actual _3.2_ Amp Draw, Average Hours Operation_8760__
After Retrofit
New WILO Stratos Model __2 x 3 – 35 __, _75gpm @ _13_’tdh
Supply __var_F, Return _+9__F 9∆T
_3/4_hp _230_Voltage, _1_Phase, Actual _0.5_ Amp Draw, Average Hours Operation_8760__
TWO-PHASE
KILOWATT (kW) = VOLTS x AMPERES x POWER FACTOR x 2
1000
THREE-PHASE
KILOWATT (kW) = VOLTS x AMPERES x POWER FACTOR x 1.73
1000
New WILO Pump
0.21kW = 0.5 x 230 x .91 x 2
0.21 x 24 x 365 x 0.07 = $129.00/year
Old Taco Pump
2.32kW = 3.2 x 460 x .91 x 1.73
2.32 x 24 x 365 x 0.07 = $1,423.00/year
Savings Per Year
$1,294.00
Boiler Manufacturer _____________________, Model ___________________________
BTU Output ________________, Current ∆T Supply F______Return F_________
Efficiency at Current ______∆T, and ________Return Water Temperature.
After WILO Stratos VFD programming to Design Conditions
New Operating ∆T Supply F______Return F_______
Boiler Efficiency at Design ∆T __________________
MCF average usage at _____% Boiler Efficiency operation at lower than design ∆T and
higher Return Temp.
MCF proposed usage at ____% Boiler Efficiency at Design.
All Boiler Manufacturers state their efficiency based upon given ∆T and inlet water
temperature, each manufacturer will have many different designs so it is imperitave to get
this information from them to deturmine design and current operating conditions. It is not
uncommon to find most boilers designed to 20 degree ∆T for 80% efficiency operating at
under 10 degree ∆T and 50% or lower efficiency.
The WILO Stratos VFD controller built in can correct this deficiency with no external inputs
required. This pump utilizes ECM technologies for electrical savings as well as Variable
Speed control and management to improve boiler efficiencies as well as pump efficiency.
Evaporator Fouling
Fouling in the evaporator tubes will also increase energy costs. Fouled evaporator tubes can cause a drop in refrigerant evaporating
pressure that reduces its density. As a result, the compressor must pump the gas to a higher pressure to remove an equivalent
amount of heat from the chilled water. Again, the compressor must work harder, which increase energy requirements.
Fouling of 0.001 Increases Energy Consumption by 10%
Based on $0.07 per kWH electricity cost and Power Factor of $ 0.91 on a Efficient Chiller at 40% load = $ 0.25 kW/Ton
Based on $0.07 per kWH electricity cost and Power Factor of $ 0.91 on a Efficient Chiller at 100% load = $ 0.57 kW/Ton
An Example of a 500 Ton Chiller operating at 100% for 2000 hours a season, which if you averaged a seasonal load this is fairly
common and fouling often exceeds 0.0042.
When making ICE for thermal storage units you can modify the hours and still reach the same costs.
Fouling of
0.0008
0.0017
0.0025
0.0033
Reduction in Chiller Efficiency kW/Ton/100% load Wasted Energy/Ton/Season 500 Ton
9%
0.62
$100.00
18%
0.672
$204.00
27%
0.724
$308.00
36%
0.775
$410.00
$ 50,000.00
$102,000.00
$154,000.00
$205,000.00
Side stream filtration down to 100 micron filtration can save real energy dollars on chiller efficiency.
______________________ Tower Basin & Condenser Tube Cleaning Cost
______________________ Cooling Water Chemical Treatment Cost / Filtering out Solids reduces Bioside Cost by 20%
______________________ Condenser Efficiency x Tonage x kW/Ton x 2000 hours/season (Clean vs. Fouled)
______________________ Make Up Water Savings keeping TSS counts down
One chiller manufacturer states without proper solids filtration efficiency is reduced by 10% in the first 24 hours of operation and
continues down for the remainder of the season.