Wood yard 3 miles 1 1 st CHP-turbine room HIGH-PRESSURE STEAM is routed from the wood-CHP boiler to the turbine. TURBINE BLADES spin at nearly 100 revolutions per second. Steam acting on the turbine blades creates mechanical energy in the TURBINE. The mechanical energy output from the turbine drives the SHAFT that connects the turbine and the GENERATOR. As the shaft spins, it rotates coils within magnets inside the generator, converting mechanical energy to electricity. The GENERATOR produces electricity at 13.8 Kv, which is sent to a transformer in a substation at a nearby power plant to increase voltage to 115 kV, matching voltage on the transmission system (the grid). Some of the electricity is used for plant operations at various voltages (4160 and 480 volts) via TRANSFORMERS, switchgear, and circuit breakers in the plant. This production of electricity by the turbine-generator reduces the HIGH-PRESSURE STEAM to EXTRACTED STEAM, which is exported to a HEAT EXCHANGER to transfer the energy to the District Energy HOT WATER SUPPLY. Low-pressure steam that cannot be utilized for heating and cooling must be cooled and the heat released through cooling towers. 1 2 3 4 5 6 CHP can capture almost 2X the amount of usable energy compared to traditional power plants HIGH-PRESSURE STEAM 1250 PSI EXTRACTED STEAM 20 PSI HEAT EXCHANGER HOT WATER SUPPLY 180° - 250°F RETURN WATER ) 160° F SHAFT TURBINE BLADES (inside TURBINE unit) GENERATOR TRANSFORMER 25 MW electricity Coils District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
Transcript
Wood yard3 miles
1st
1st
CHP-turbine room
HIGH-PRESSURE STEAM is routed from the wood-CHP boiler to the turbine.
TURBINE BLADES spin at nearly 100 revolutions per second. Steam acting on the turbine blades creates mechanical energy in the TURBINE.
The mechanical energy output from the turbine drives the SHAFT that connects the turbine and the GENERATOR. As the shaft spins, it rotates coils within magnets inside the generator, converting mechanical energy to electricity.
The GENERATOR produces electricity at 13.8 Kv, which is sent to a transformer in a substation at a nearby power plant to increase voltage to 115 kV, matching voltage on the transmission system (the grid). Some of the electricity is used for plant operations at various voltages (4160 and 480 volts) via TRANSFORMERS, switchgear, and circuit breakers in the plant.
This production of electricity by the turbine-generator reduces the HIGH-PRESSURE STEAM to EXTRACTED STEAM, which is exported to a HEAT EXCHANGER to transfer the energy to the District Energy HOT WATER SUPPLY.
Low-pressure steam that cannot be utilized for heating and cooling must be cooled and the heat released through cooling towers.
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CHP can capture almost 2Xthe amount of usable energycompared to traditional power plants
HIGH-PRESSURE STEAM 1250 PSI
EXTRACTED STEAM 20 PSI
HEAT EXCHANGER
HOT WATER SUPPLY 180° - 250°F
RETURN WATER 160° F
SHAFTTURBINE BLADES
(inside TURBINE unit) GENERATOR
TRANSFORMER
25 MW electricity
Coils
District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
1000 tons OF WOOD CHIPS EACH DAYto generate electricity and heat
Biomass (WOOD CHIPS) moves through a conveyor that drops the wood chips down into five METERING BINS.
The METERING BINS control the flow of WOOD CHIPS into the BOILER, to optimize combustion conditions. NATURAL GAS is injected to increase the combustion temperature and stability.
The boiler walls are lined with pipes filled with water, which absorb the heat from the combustion and raise the temperature of the water to HIGH-PRESSURE STEAM. High-pressure steam traverses the SUPERHEATER, which prepares the steam to be sent to the TURBINE.
EXTRACTED STEAM captured from the electricity generation process is used to heat water for the District Energy HOT WATER SUPPLY.
The combustion of the WOOD CHIPS and NATURAL GAS creates combustion gases (EXHAUST GAS), which pass from the boiler through an ELECTROSTATIC PRECIPITATOR, which removes particulate before exhaust gas is released through the stack.
Ash remaining from the combustion is beneficially reused whenever possible, primarily for agriculture purposes.
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District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
Wood yard3 miles
1st
1st
coal-natural gas boilers
COAL is dispatched onto a flat GRATE, to allow combustion air to contact the coal. The grate moves the coal into the boiler for combustion at ~2300°F.
The boiler walls are lined with pipes filled with water, which absorbs the heat from the combustion and raise the temperature of the FEEDWATER to STEAM.
The STEAM from this process travels to a HEAT EXCHANGER to transfer the energy to the District Energy HOT WATER SUPPLY. Once heat is removed from the steam through the heat exchanger, it is condensed to water which is returned to the BOILER as FEEDWATER and cycled back through the pipes in the boiler walls.
As the COAL burns, it produces EXHAUST GAS and ASH. The gases and lighter ash (fly ash) are filtered through a CYCLONE before final release from the stack as exhaust gas. The heavier ash (bottom ash) is collected at the bottom of the boiler and removed.
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coal boilers are primarily used to
meet peak needsduring winter months
High-pressure STEAM 150 PSI HEAT EXCHANGER
FEEDWATER
COAL
CYCLONEHOT WATER SUPPLY 180° - 250°F
RETURN WATER 160° F
EXHAUST GAS
GRATE
Bottom ASH
Fly ASH
Inside BOILER reaches 2300°F
Natural gas
District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
Wood yard3 miles
1st
1st
natural gas-oil boilers
HEAT EXCHANGER
FEEDWATER
Fuel injector
HOT WATER SUPPLY 180° - 250°F
NATURAL GAS
OIL
STEAM 150 PSI or HOT WATER
300 - 340 ° F output
EXHAUST GAS
Return water 160° F
Inside BOILER reaches 2300°F
NATURAL GAS-OIL BOILERShave a combined capacity of
106 MW THERMAL
ENERGY
the 4
NATURAL GAS is injected into the boiler under pressure, where it is ignited. Natural gas is continually added to sustain the fire and temperature (~2100 - 2400°F). The boilers primarily run onnatural gas, with the option of OIL when natural gas is not readily available.
The boiler walls are lined with pipes filled with water, which absorbs the heat from the combustion and raise the temperature of the FEEDWATER to STEAM. Two of the boilers export STEAM. Two of the boilers export HOT WATER.
When steam is exported from a boiler, it uses a heat exchanger to transfer the energy to the District Energy HOT WATER SUPPLY. When hot water is exported, it can heat the hot water supply directly.
Once heat is removed from the STEAM through the HEAT EXCHANGER, it is condensed to water which is returned to the BOILER as FEEDWATER and cycled back through the pipes in the boiler walls.
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District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
Wood yard3 miles
1st
delivery and storage area
THERMAL STORAGE TANK
WOOD STORAGE SILOS
Additional fuel delivery
Transport trucks have MOVING FLOORS for efficient
unloading of wood
WOOD DELIVERY BAY
ASH removal
COOLING TOWERS
VAPOR
45 truckloads 1,000 tons
of biomass wood chip fuel is delivered to the plant each day
OR
UPTO
The WOOD STORAGE SILOS hold more than 600 tons of wood fuel, the amount the plant burns overnight.
The THERMAL STORAGE TANK is 72 feet high by 80 feet in diameter and stores 2.5 million gallons of water. It is 1 of 2 tanks used in the system.
The WOOD DELIVERY BAY allows 2 trucks to simultaneously unload. Delivery trailers are equipped with MOVING FLOORS for efficient unloading. A series of conveyor belts moves the wood fuel from the delivery bay to the storage silos.
Wood ASH is removed from the system, trucked to other locations, and either used in landfill cover or for agricultural land applications.
COOLING TOWERS are used to reduce the heat of steam to condense the steam to a liquid before releasing it to the atmosphere as VAPOR.
District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
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1 2 3 4
District Energy St. Paul Tour Signs contain original material developed for educational purposes. Please do not utilize this artwork or content for your own purposes without express permission from District Energy St. Paul.
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