District Heating/Cooling System Optimization - The PERTAN Group
District Heating/Cooling System Optimization - The PERTAN Group
District Heating/Cooling System Optimization - The PERTAN Group
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<strong>District</strong> <strong>Heating</strong>/<strong>Cooling</strong><br />
<strong>System</strong> <strong>Optimization</strong>:<br />
Principles and Examples<br />
from US Army Studies<br />
Szenarienvorschläge für die<br />
„sanfte Energiewende“ –<br />
„Strukturoptimierung in<br />
Flächengebieten“, SWM<br />
September 20, 2009<br />
Dr. Stephan Richter<br />
GEF Ingenieur AG<br />
Ferdinand-Porsche-Str. 4a<br />
69181 Leimen<br />
Germany<br />
www.gef-ingenieur-ag.de<br />
1
Agenda<br />
1. Overview and Technical Description of a Central Energy <strong>System</strong><br />
2. Operation Modes with Variable Temperature-Variable Flow <strong>System</strong>s<br />
3. Contributions and Outcomes from Energy Assessments<br />
I. Conceptual Ideas<br />
II. Searching for ECMs<br />
I. Examples from the Fort Bragg <strong>Heating</strong> and <strong>Cooling</strong> Master Plan Study<br />
II. Experiences from about 25 On-Site Assessments<br />
2
Overview on Central Energy <strong>System</strong>s<br />
• Purpose of Central Energy <strong>System</strong>s<br />
- Provide heating and/or cooling to a group of buildings generated in a<br />
Central Energy Plant (CEP)<br />
- Heat can be used for space heating, Domestic Hot Water (DHW)<br />
preparation and for technical purposes (e.g. pressing units,<br />
dehumidification, sterilization, technical shaping etc.)<br />
- <strong>Cooling</strong> can be used for air conditioning, dehumidification and heat removal<br />
from processes<br />
• Basic Principles<br />
- <strong>The</strong> CEP generates thermal energy at a certain temperature. <strong>The</strong> thermal<br />
energy is then transported in pipelines from the CEP to the location of use.<br />
Mostly the transport medium is water or steam. At the location of use a part<br />
of the energy content is taken from the water and the temperature is<br />
reduced (= heating) or raised (cooling). <strong>The</strong> water is then transported back<br />
to the CEP and used again.<br />
- <strong>The</strong> temperature of the transported water depends on the requirements of<br />
the users: Requirements are the temperatures itself and the energy<br />
capacity.<br />
3
Central Energy <strong>System</strong>s at a Glance<br />
Combined Heat and Power Generation for <strong>District</strong> <strong>Heating</strong><br />
Turbine and Generator<br />
Boiler<br />
Transformer<br />
Power Line<br />
Heat Users and Substations<br />
Central Heat<br />
Exchanger<br />
Return Pipe<br />
Supply Pipe<br />
4
Central Energy <strong>System</strong>s at a Glance<br />
Distribution Pumps<br />
Supply Pipe<br />
Bypass<br />
Building<br />
Substation<br />
Δp<br />
DHW<br />
Space<br />
<strong>Heating</strong><br />
Boiler<br />
Return Pipe<br />
Water Treatment<br />
5
Central Energy <strong>System</strong>s at a Glance<br />
Distribution Pumps<br />
Supply Pipe<br />
Bypass<br />
Building<br />
Substation<br />
Δp<br />
DHW<br />
Boiler<br />
Space<br />
<strong>Heating</strong><br />
Return Pipe<br />
Water Treatment<br />
6
Pressure Diagram<br />
Pressure Drop<br />
Pump<br />
CEP<br />
Heat Users<br />
Problem:<br />
horizontal distance between CEP and User<br />
As distance to heat users increases the result is a greater pressure drop. A increase of sea<br />
level high results into a greater pressure drop, too.<br />
Differential pressure at the critical building needs to be higher than 10 to 14 psi<br />
7
Agenda<br />
1. Overview and Technical Description of a Central Energy <strong>System</strong><br />
2. Operation Modes with Variable Temperature-Variable Flow <strong>System</strong>s<br />
3. Contributions and Outcomes from Energy Assessments<br />
I. Conceptual Ideas<br />
II. Searching for ECMs<br />
I. Examples from the Fort Bragg <strong>Heating</strong> and <strong>Cooling</strong> Master Plan Study<br />
II. Experiences from about 25 On-Site Assessments<br />
8
Heat Demand Depends on the Ambient Temperature<br />
105 MW<br />
20°F 40°F 60°F 80°F 100°F<br />
3.5x10 8 BTU<br />
90 MW<br />
correlation factor ~ 0.75 to 0.9<br />
3.0x10 8 BTU<br />
Total Sum of Heat Demand<br />
75 MW<br />
60 MW<br />
45 MW<br />
30 MW<br />
15 MW<br />
2.5x10 8 BTU<br />
2.0x10 8 BTU<br />
1.5x10 8 BTU<br />
1.0x10 8 BTU<br />
5.0x10 7 BTU<br />
0 MW<br />
0.0 BTU<br />
-15°C 0°C 15°C 30°C 45°C<br />
Outdoor Temperature<br />
9
Satisfying the Heat Demand by Adapting the Flow and the<br />
Supply Temperature<br />
Power<br />
P<br />
Central<br />
Energy<br />
<strong>System</strong><br />
= Flow × Heat Capacity<br />
= Q&<br />
= m&<br />
× c × ΔT<br />
p<br />
of<br />
Water<br />
× Temperaturedifference<br />
Variable Parameter:<br />
‣ Supply and Return Temperature<br />
‣ Water Flow (= Water Velocity)<br />
Approach<br />
Keep the flow dm / dt and the return temperature T R constant and vary the<br />
supply temperature T S<br />
10
Central <strong>Heating</strong> <strong>System</strong> Supply Temperature Curve<br />
150°C<br />
0°F 20°F 40°F 60°F 80°F 100°F 120°F<br />
300°F<br />
135°C<br />
280°F<br />
Supply Temperature<br />
120°C<br />
105°C<br />
90°C<br />
75°C<br />
260°F<br />
240°F<br />
220°F<br />
200°F<br />
180°F<br />
160°F<br />
60°C<br />
140°F<br />
-20°C -10°C 0°C 10°C 20°C 30°C 40°C 50°C<br />
Outdoor Temperature<br />
11
Why Shall the Supply Temperatures be as Low as Possible?<br />
Efficiency of Plant Type<br />
Geothermal<br />
@ 100°C = 215°F<br />
Efficiency<br />
1990 Design Hard Cole CHP @ 530°C = 990°F<br />
Waste Incineration Plant<br />
@ 390°C = 735°F<br />
Biomass Plant @ 450°C = 840°F<br />
=<br />
T Warm<br />
T<br />
T Cold<br />
Warm<br />
T<br />
Combined Cycle Plant<br />
@ 1100°C = 2010°F<br />
2035 Design Hard Cole CHP<br />
@ 700°C = 1290°F<br />
Energy can<br />
be used<br />
not be used<br />
30 120 210 300 390<br />
T cold in°C = Return Temp from Distribution <strong>System</strong><br />
−T<br />
Warm<br />
Cold<br />
‣ In an existing system a reduction of<br />
the return temperature (= a better<br />
use of provided temperature) can<br />
increase the distribution system’s<br />
capacity.<br />
‣ More users can be supplied by the<br />
same diameters and installation<br />
costs.<br />
‣ In case of new network constructions<br />
one can use smaller<br />
diameters and, thus, save costs.<br />
‣ Flow, pressure drop and electricity<br />
for pumps can be reduced.<br />
‣ <strong>The</strong> ratio of power to heat<br />
generation increases if less<br />
heat/steam is taken from the<br />
turbine (e.g. in Munich a additional<br />
power generation of 100 GWh el per<br />
year can be achieved).<br />
12
Agenda<br />
1. Overview and Technical Description of a Central Energy <strong>System</strong><br />
2. Operation Modes with Variable Temperature-Variable Flow <strong>System</strong>s<br />
3. Contributions and Outcomes from Energy Assessments<br />
I. Conceptual Ideas: Examples from the Fort Bragg <strong>Heating</strong> and <strong>Cooling</strong><br />
Master Plan Study<br />
II. Experiences from about 25 On-Site Assessments<br />
13
Current Conditions: Overview on the Central Plants and<br />
Distribution <strong>System</strong> – <strong>Heating</strong><br />
14
Overview <strong>Heating</strong> <strong>System</strong>s<br />
82 nd <strong>Heating</strong><br />
96x10 6 BTU/h<br />
icl. DUCT Burner:<br />
140x10 6 BTU/h<br />
C-Area<br />
Faith Barracks<br />
Peak load<br />
12x10 6 BTU/h<br />
COSCOM<br />
50x10 6 BTU/h<br />
C-Area<br />
Peak load<br />
40x10 6 BTU/h<br />
Steam and<br />
Hot Water<br />
M-Area<br />
Peak load<br />
5x10 6 BTU/h<br />
D-Area<br />
Zone 1<br />
Peak load<br />
4x10 6 BTU/h<br />
E-Area<br />
Zone 1<br />
Peak load<br />
4x10 6 BTU/h<br />
CMA<br />
109.5x10 6 BTU/h<br />
D-Area<br />
Zone 2+3<br />
Peak load<br />
8x10 6 BTU/h<br />
4x10 6 BTU/h<br />
H-Area<br />
Peak load<br />
12x10 6 BTU/h<br />
E-Area<br />
Zone 2<br />
Peak load<br />
5x10 6 BTU/h<br />
SOCOM<br />
40x10 6 BTU/h<br />
15
SOCOM (<strong>Heating</strong> Zone 1) – Log Data<br />
175°C<br />
SOCOM Hot Water Zone 1<br />
HW Zone 1 Supply<br />
HW Zone 1 Return<br />
120m³/h<br />
500gpm<br />
300°F<br />
150°C<br />
100m³/h<br />
250°F<br />
125°C<br />
80m³/h<br />
400gpm<br />
200°F<br />
100°C<br />
60m³/h<br />
300gpm<br />
150°F<br />
75°C<br />
50°C<br />
40m³/h<br />
200gpm<br />
100°F<br />
25°C<br />
20m³/h<br />
100gpm<br />
50°F<br />
0°C<br />
0m³/h<br />
0 2000 4000 6000 8000 10000 12000 14000<br />
0gpm<br />
Hours since October 05<br />
16
SOCOM (<strong>Heating</strong> Zone 1) – Model Parameter<br />
Total building heat load (from PNNL FEDS<br />
model):<br />
4.46×10 6 Btu/h = 1,306 kW<br />
Peak load taken from log data 4.10 ×10 6 Btu/h = 1,200 kW<br />
Load factor ( peak load / total load<br />
) 84%<br />
Peak temperatures T supply<br />
/T return<br />
340°F/250°F = 170°C/120°C<br />
Water mass flow calculated by flow model 84.5 gpm = 19.2 m³/h<br />
Δp @ CEP calculated by flow model 33.4 psi = 2.3 atm<br />
17
SOCOM (<strong>Heating</strong> Zone 1) – Results of Flow Model<br />
Line colors<br />
critical building<br />
Rectangle colors<br />
CEP<br />
18
Operating a Modern Variable Flow Hot Water <strong>System</strong> –<br />
Hydraulic Flow Analysis in Peak Load Case<br />
supply<br />
return<br />
Pump<br />
CEP<br />
19
Current Conditions: Overview on the Central Plants and<br />
Distribution <strong>System</strong> – <strong>Cooling</strong><br />
20
Overview <strong>Cooling</strong> <strong>System</strong>s<br />
82 nd <strong>Heating</strong><br />
1820 tons<br />
C-Area<br />
Faith Barracks<br />
Peak load<br />
800 tons<br />
COSCOM<br />
1344 tons<br />
C-Area<br />
Peak load<br />
2600 tons<br />
82 nd <strong>Cooling</strong><br />
4400 tons<br />
M-Area<br />
Peak load<br />
1000 tons<br />
D-Area<br />
Zone 1<br />
Peak load<br />
600 tons<br />
H-Platons<br />
H-Plant<br />
2000 tons<br />
2000 tons<br />
E-Area<br />
Zone 1<br />
Peak load<br />
1000 tons<br />
CMA<br />
D-Area<br />
Zone 2<br />
H-Area<br />
E-Area<br />
Zone 2<br />
SOCOM<br />
3413 tons<br />
Peak load<br />
480 tons<br />
Peak load<br />
1100 tons<br />
Peak load<br />
740 tons<br />
2100 tons<br />
21
H-Plant (<strong>Cooling</strong>) – Log Data<br />
100°F<br />
40°C<br />
H-Plant Chilled Water<br />
CW Supply<br />
CW Return<br />
1200m³/h<br />
5000gpm<br />
80°F<br />
30°C<br />
1000m³/h<br />
800m³/h<br />
4000gpm<br />
20°C<br />
600m³/h<br />
3000gpm<br />
60°F<br />
400m³/h<br />
2000gpm<br />
10°C<br />
40°F<br />
200m³/h<br />
1000gpm<br />
0°C<br />
0m³/h<br />
0 2000 4000 6000 8000 10000 12000 14000<br />
Hours since October Oktober 05<br />
0gpm<br />
22
H-Plant (<strong>Cooling</strong>) – Model Parameters<br />
Total building cooling load (from<br />
PNNL FEDS model):<br />
1581 tons = 5,554 kW<br />
Peak load taken from log data 1110 tons = 3,900 kW<br />
Load factor ( peak load / total load<br />
) 70%<br />
Peak temperatures T supply<br />
/T return<br />
43°F/52°F = 6°C/11°C<br />
Water mass flow calculated by<br />
flow model<br />
Δp @ CEP calculated by flow<br />
model<br />
2947 gpm = 669.4 m³/h<br />
124.7 psi = 8.6 atm<br />
23
H-Plant (<strong>Cooling</strong>) – Results of Flow Model<br />
CEP<br />
critical building<br />
Line colors<br />
Rectangle colors<br />
24
Interconnection of the Central Plant and Distribution<br />
<strong>System</strong> – <strong>Cooling</strong><br />
25
Connected <strong>Cooling</strong> Net in the Central <strong>Cooling</strong><br />
<strong>System</strong><br />
critical buildings<br />
CEP<br />
CEP<br />
CEP<br />
CEP<br />
critical buildings<br />
26
New <strong>Cooling</strong> Pipes Required to add Bldg. to the Central <strong>Cooling</strong><br />
<strong>System</strong> and Locations where larger Pipe Diameters are Needed<br />
‣ To interconnect the heating<br />
systems, the green pipes are<br />
additionally required<br />
‣ <strong>The</strong> pipes in blue must have<br />
larger diameters to interconnect<br />
the systems<br />
‣ Pipes that need to have larger<br />
sizes are required due to the<br />
growth of the system in red<br />
27
New <strong>Cooling</strong> Pipes Required to add Bldg. to the Central <strong>Cooling</strong><br />
<strong>System</strong> and Locations where larger Pipe Diameters are Needed<br />
28
Heat Generation incl. Heat for Absorption Chillers<br />
<strong>Heating</strong> Load<br />
60 MW<br />
50 MW<br />
40 MW<br />
30 MW<br />
20 MW<br />
10 MW<br />
0 MW<br />
Boiler:<br />
peak: 118.2x10 6 BTU/Hr<br />
annual: 1.5x10 9 BTU p.a.<br />
Duct-Bruner:<br />
peak: 44x10 6 BTU/Hr<br />
annual: 15.3x10 9 BTU p.a.<br />
Gas Turbine<br />
Heat from 82nd <strong>Heating</strong> GT for 82nd <strong>Heating</strong> Absorption Chiller<br />
Heat from CMA New GT<br />
Heat from New CMA GT for NEW CMA 1-Stage-Absorption Chiller<br />
Duct Burner<br />
Boiler<br />
Demand<br />
New CMA Gas Turbine:<br />
peak: 34x10 6 BTU/Hr<br />
annual: 79.9x10 9 BTU p.a.<br />
Gas Turbine:<br />
peak: 36x10 6 BTU/Hr<br />
annual: 263.9x10 9 BTU p.a.<br />
Potential of additional heat for<br />
absorption chiller for 365 days per<br />
year chilled water supply<br />
New CMA Gas Turbine:<br />
peak: 34x10 6 BTU/Hr<br />
annual: 154.7x10 9 BTU p.a.<br />
82nd <strong>Heating</strong> Gas Turbine:<br />
peak: 10x10 6 BTU/Hr<br />
annual: 32.0x10 9 BTU p.a.<br />
1000 2000 3000 4000 5000 6000 7000 8000<br />
200x10 6 BTU/Hr<br />
180x10 6 BTU/Hr<br />
160x10 6 BTU/Hr<br />
140x10 6 BTU/Hr<br />
120x10 6 BTU/Hr<br />
100x10 6 BTU/Hr<br />
80x10 6 BTU/Hr<br />
60x10 6 BTU/Hr<br />
40x10 6 BTU/Hr<br />
20x10 6 BTU/Hr<br />
0x10 6 BTU/Hr<br />
Hours<br />
29
Suggestion: Using Pre-Insulated Bonded Pipe<br />
Components of pre-insulated bounded pipe<br />
system:<br />
Water carrying pipe made from steel.<br />
Bonding insulation made from PUR foam having<br />
a leak detection system.<br />
Jacket pipe made from polyethylene (PE).<br />
It is recommended to engage a quality control<br />
and management system during the<br />
installation of the pipes to ensure the proper<br />
installation. Sensible issues are the bevel<br />
seams, the bushings and the adding of<br />
insulating foam at field welded connections, the<br />
sand bed, the proper connection of the leak 30<br />
detection system and the expansion cushions.
Comparison between Reality and Drawings<br />
31
Schematic of Pre-Insulated Bonded Pipes<br />
Buried Valve<br />
Anchor<br />
T-Junktion<br />
Elbow<br />
Expansion<br />
Cushion<br />
Bushing<br />
32<br />
32
Cost Savings by Using European Type Standard Pre-<br />
Insulated Bonded Pipes Compared to Steel-Jacket Pipes<br />
75.0 Mil. EURO<br />
Total 5-Years Costs for replacing Steel-Jacket Steam Pipes by Kind<br />
Total 5-Years Costs for replacing Steel-Jacket Steam Pipes by Pre-Ins. Bounded Pipes<br />
Total 5-Years Savings<br />
62.5 Mil. EURO<br />
50.0 Mil. EURO<br />
37.5 Mil. EURO<br />
25.0 Mil. EURO<br />
12.5 Mil. EURO<br />
0.0 Mil. EURO<br />
-12.5 Mil. EURO<br />
-25.0 Mil. EURO<br />
2005 2010 2015 2020 2025 2030 2035<br />
5-Years Phase<br />
33
Agenda<br />
1. Overview and Technical Description of a Central Energy <strong>System</strong><br />
2. Operation Modes with Variable Temperature-Variable Flow <strong>System</strong>s<br />
3. Contributions and Outcomes from Energy Assessments<br />
I. Conceptual Ideas: Examples from the Fort Bragg <strong>Heating</strong> and <strong>Cooling</strong><br />
Master Plan Study<br />
II. Experiences from about 25 On-Site Assessments<br />
34
Central Energy <strong>System</strong>s at a Glance<br />
Combined Heat and Power Generation for <strong>District</strong> <strong>Heating</strong><br />
Turbine and Generator<br />
Boiler<br />
Transformer<br />
Power Line<br />
Heat Users and Substations<br />
Central Heat<br />
Exchanger<br />
Return Pipe<br />
Supply Pipe<br />
35
Potentials for ECMs in Distribution Piping <strong>System</strong><br />
1. Central Plant<br />
2. Piping and related Construction<br />
3. Man Holes<br />
4. Operation Modes<br />
36
1. Central Plants<br />
• Oversized or undersized pumps<br />
• Wrong/missing controls for VF-pumps<br />
• High return temperatures from field (e.g. cavitation of pumps)<br />
• Poor water treatment<br />
• Missing deaerator<br />
• Wrong sized expansion tank<br />
• Poor piping insulation<br />
• Leakages on fittings, valves, pipes, …<br />
• Oversized or undersized boilers<br />
• All problems with boilers/chillers (Presentation Al Woody/Scot Duncan)<br />
37
2. Piping <strong>System</strong><br />
• Oversized or undersized pumps (pressure drops)<br />
• Poor insulation<br />
• Improper junctions (welding, bushings, …)<br />
• Wrong connection of leak detection system wires or missing leak detection<br />
system<br />
• Missing corrosion protection if steel pipes<br />
• Missing/undersized stress/expansion compensation<br />
• Temperature too high regarding the demand (e.g. steam for space heating and<br />
DHW)<br />
• Too high differential pressure at critical bldg.<br />
• Leakages<br />
• Missing/unadjusted expansion compensation and anchors<br />
• If concrete ducts: missing down-grade in ducts<br />
• If steam: condensate losses and problems with steam traps (steam flashes)<br />
• Missing venting at high points<br />
38
3. Man Holes (if needed or existing)<br />
• Flooded man holes by groundwater, rain, …)<br />
• Uninsulated valves, fittings, …<br />
• Leaky or missing covers<br />
• Missing pump/drainage in man holes<br />
• Oversized man holes<br />
39
4. Operation Modes<br />
• Too high supply water temperatures regarding usage and demand<br />
• Constant supply temperatures<br />
• Constant flow<br />
• Steam distribution for space heating and DHW<br />
• Unadjusted codensate pumps in Bldg.<br />
• Too high return temperatures while flow is constant<br />
• …<br />
40
Variable Speed Pumps do not Work Proper<br />
Solution<br />
<strong>The</strong> variable speed pumps, frequency drivers, isolation valves and valve actuators must be<br />
replaced with new variable flow equipment. This enables the adaptation of the mass flow in<br />
the central system to meet the cooling load of the building served by central chilled water.<br />
41
Flooded Trenches and Man Holes<br />
Savings<br />
Normally pipes found in flooded pits require replacement<br />
after 15 years rather than after 30 years at a total cost<br />
estimated to be $ 360,000. This investment can be<br />
postponed by 15 years. Averaging this cost over 15 years<br />
results in an annual saving of about $ 24,000.<br />
Payback<br />
<strong>The</strong> resulting payback period is 0.125 years or one<br />
month.<br />
42
Stop Leaks – Fix Broken Release Valve<br />
Savings<br />
A 465 gal/hr leak equals about 4,000<br />
kgal/yr while the costs for 1 kgal of city<br />
water are $ 4. Thus, the annual<br />
savings are about $ 16,000.<br />
Investment<br />
<strong>The</strong> cost for a 1” valve including a full<br />
day of labor is about $ 500.<br />
Payback<br />
<strong>The</strong> resulting payback period is 0.03<br />
years or 11 days.<br />
43
Problems with Pipe Installation Requires Quality<br />
Management and Control of this type of Construction<br />
44
2 <strong>System</strong>s within a few Feet Distence<br />
#3700<br />
2 Boilers<br />
4,580 MMBH<br />
total<br />
HW 180°F<br />
60…70 psi<br />
seasonal<br />
4 Bldg.<br />
peak: 1,371 MMBH<br />
annual: 1,921 mmBTU<br />
#3700<br />
4 Bldg.<br />
1 Chiller<br />
240 tons total<br />
peak: 94 tons<br />
annual: 1,128 mmBTU<br />
#3709<br />
2 Boilers<br />
4,580 MMBH<br />
total<br />
HW 180°F<br />
60…70 psi<br />
seasonal<br />
4 Bldg.<br />
peak: 1,371 MMBH<br />
annual: 1,921 mmBTU<br />
#3709<br />
4 Bldg.<br />
2 Chillers<br />
250 tons total<br />
peak: 94 tons<br />
annual: 1,128 mmBTU<br />
45
Poor Piping Insulation in CEP<br />
46
Uninsulated Fittings<br />
47
Brocken Insulation in Overgound Piping<br />
48
Fibre Glas Condensate Pipe after Steam<br />
Flusehes<br />
49
Man Holes Without Cover and Pumps<br />
50
Man Holes Without Cover and Pumps<br />
51
Leakages in Pipes without Leakges Control<br />
and Detection <strong>System</strong><br />
52
Unsealed Foam Opening<br />
53
Poorly Installed Bushing<br />
54
Highly Corroted Equipment<br />
55
Steam Leakages<br />
56
Uninsulated Flange<br />
57
Flooded Man Hole<br />
58
Leaky Valve in Man Hole<br />
59
Swimming Pool in Man Hole<br />
60
Who is GEF Ingenieur AG ?<br />
GEF is a engineering and energy economic<br />
consulting and design company for energy<br />
supply, focused on district heating. We are<br />
developing economic solutions in the field of<br />
energy supply, media transport and environment<br />
related technologies for our customers since<br />
almost 25 years.<br />
GEF Office in Leimen, Germany<br />
www.gef-ingenieur-ag.de<br />
GEF Office in Chemnitz, Germany<br />
Our neighborship in Leimen<br />
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