UVM-CP-24-SD
CHILLER GENERATOR SYSTEM UNIT 1 AND 2
SYSTEM DESCRIPTION
December 2011
University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
PREFACE
This System Description has been designed to assist you in meeting the requirements of Module
UVM-CP-24 of the Central Heating and Cooling Plant Operator Training and Certification
Program. It contains information about the Chiller Generator System Unit 1 and 2. This
includes system purpose, flow path, and details about major system components and operation.
You should review chapter objectives. In doing so you will be better prepared to learn the
required information. You should also walk down the system and identify the components and
controls. Should you have additional questions about the system, ask your Supervisor.
Operators are responsible for learning the information contained in this document. They are also
responsible for making proper inspections, recording and logging information, reporting
problems of the Chiller Generator System Unit 1 and 2.
A separate document, System Operating Procedure (UVM-CP-24-SOP), covers detailed
operation of the Chiller Generator System Unit 1 and 2.
December 2011
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
CHILLER GENERATOR SYSTEM UNIT 1 AND 2
TRAINING SYSTEM DESCRIPTION
TABLE OF CONTENTS
1.0 Introduction .......................................................................................................................... 4 1.1 Purpose ............................................................................................................................. 4 1.2 Basic System Description ................................................................................................ 4 1.3 System Flow Path ............................................................................................................. 4 2.0 System Major Components ................................................................................................. 8 2.1 Compressor..................................................................................................................... 10 Compressor .......................................................................................................................... 10 2.2 Steam Turbine ................................................................................................................ 11 Steam Turbine Data ............................................................................................................ 12 Steam Turbine Data ............................................................................................................ 12 2.3 Evaporator ...................................................................................................................... 14 2.4 Condenser ....................................................................................................................... 14 Condenser Data ................................................................................................................... 15 2.5 Steam Condenser Package ............................................................................................ 16 2.7 Power Panel .................................................................................................................... 18 2.8 OptiView Control Center .............................................................................................. 19 List of Figures:
Figure 1 – Compressor .................................................................................................................. 10 Figure 2 – Steam Turbine ............................................................................................................. 12 Figure 3 – Steam Turbine Emergency Stop .................................................................................. 13 Figure 4 – Evaporator ................................................................................................................... 14 Figure 5 – Condenser .................................................................................................................... 15 Figure 6 – Steam Condenser Package ........................................................................................... 17 Figure 7 – Power Panel and OptiView Control Center................................................................. 18 Figure 8 –OptiView Control Center ............................................................................................. 19 December 2011
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
List of Drawings
Drawing 1 – Chiller Generator System (Typical) Block Diagram ................................................. 5
Drawing 2 – Refrigerant Flow Diagram ......................................................................................... 6
Drawing 3 – Steam and Condensate Flow Diagram ....................................................................... 7
References:
University of Vermont Diagrams
University of Vermont York Chiller Manual
York Model YST MaxE Steam-Turbine Drive Centrifugal Liquid Chiller Operating and
Maintenance Manual
York OptiView Control Center MaxE Steam Turbine Drive Centrifugal Liquid Chiller
Operation Manual
December 2011
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University of Vermont
Chiller Generator System Unit 1 and 2
1.0
Central Heating and Cooling Plant
UVM-CP-24-SD
Introduction
Chapter Objectives:
Describe the purpose of the Chiller Generator System Unit 1 and 2.
1. State, from memory, the purpose of the Chiller Generator System Unit 1 and 2.
2. Draw a simplified diagram of the Chiller Generator System Unit 1 and 2.
3. Describe the flow path and how the Chiller Generator System Unit 1 and 2 performs their
functions.
4. State, from memory, the names and purpose of the major Chiller Generator System Unit
1 and 2 components.
5. List the normal Chiller Generator System Unit 1 and 2 operating parameters.
1.1
Purpose
The purpose of the Chiller Generator System Units 1 and 2 is to provide chilled water for
campus air conditioning and equipment that require cooling.
1.2
Basic System Description
The Unit 1 and Unit 2 Chillers are York YST Steam Turbine Driven Centrifugal Compressor
Chillers manufactured by Johnson Controls. The Chillers operate on Refrigerant R-134a. Each
Chiller system includes the Compressor, Evaporator, Condenser, Steam Turbine, Steam
Condenser, Lubrication Systems, Power Panel, OptiView Control Center, and all interconnecting
unit piping and wiring.
The Chiller Generator System is manufactured by Johnson Controls under their York brand.
Other manufacturers supply some components.
1.3
System Flow Path
Water from the Cooling Towers flows through the tubes in the Evaporator where boiling
refrigerant evaporates and absorbs heat from the water. The refrigerant rises and passes through
Eliminators that remove any water droplets. The dry refrigerant gas flows to the Compressor
suction. The Compressor raises the temperature and pressure of the refrigerant through
centrifugal force. The higher-pressure refrigerant gas exists the Compressor and enters the
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Condenser where the latent heat of the refrigerant is removed and the refrigerant condenses to a
liquid by water flowing through the tubes. The liquid refrigerant passes through a subcooling
section in the bottom of the Condenser where the liquid refrigerant is cooled to a lower
temperature again by water inside tubes. The higher-pressure refrigerant liquid then expands
into the Evaporator through a Level Control Valve controlled by the OptiView Control Center
based on the signal from a Refrigerant Level Sensor located in the Subcooler.
The water that is chilled in the Evaporator is pumped to the point of use, which includes campus
air conditioning and equipment requiring cooling.
The Compressor is direct driven by a variable speed condensing Steam Turbine. High pressure
steam from the High Pressure Steam Header is used to power the Steam Turbine. The Steam
Condenser condenses exhaust steam from the Steam Turbine to water and the condensate is
collected in the Hotwell. When the Level Measurement Transmitter senses Condenser Hotwell
is full, surplus condensate is returned to the Boilers.
Drawing 1 – Chiller Generator System (Typical) Block Diagram
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Drawing 2 – Refrigerant Flow Diagram
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Drawing 3 – Steam and Condensate Flow Diagram
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University of Vermont
Chiller Generator System Unit 1 and 2
2.0
Central Heating and Cooling Plant
UVM-CP-24-SD
System Major Components
Chapter Objectives:
1. Describe how the Chiller Generator System Unit 1 and 2 Components perform their
functions and how they interface with other system components.
2. Draw from memory a diagram of the Chiller Generator System Unit 1 and 2 showing
major components.
3. State from memory the names and purposes of Chiller Generator System Unit 1 and 2
major components.
4. Describe the construction of and flow paths through the major components.
The Chiller Generator System Units 1 and 2 each consist of the following major components:
1.
Compressor
2.
Steam Turbine
3.
Evaporator
4.
Condenser
5.
Steam Condenser Package
6.
Power Panel
7.
OptiView Control Center
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Drawing 3 – Chiller Components
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University of Vermont
Chiller Generator System Unit 1 and 2
2.1
Central Heating and Cooling Plant
UVM-CP-24-SD
Compressor
The Compressor is the part of the Chiller that pressurizes refrigerant gas before it is sent to the
Condenser (also called the Refrigerant Compressor). Dry refrigerant gas flows to the
Compressor suction. The Compressor raises the temperature and pressure of the refrigerant
through centrifugal force. This higher-pressure refrigerant gas exits the Compressor and enters
the Condenser. The Compressor is mounted to a Driveline Base and connected to the Steam
Turbine with a flexible disc coupling.
Figure 1 – Compressor
Compressor
Manufacturer
York
Type
Open drive single impeller centrifugal
Drive
Steam Turbine
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University of Vermont
Chiller Generator System Unit 1 and 2
2.2
Central Heating and Cooling Plant
UVM-CP-24-SD
Steam Turbine
The Steam Turbine is a high efficiency multistage design operating at a nominal 4500 rpm
design maximum speed.
The Steam Turbine is packaged on a Driveline Base. The Driveline Base has a mating flange on
the shaft end of the package that bolts directly to the Compressor D-flange face providing a rigid
interface between the Steam Turbine and the Compressor.
The Steam Turbine casing is horizontally split to allow longitudinal thermal expansion without
affecting alignment or efficiency of the Steam Turbine.
Protection against overspeed is built into the automatic speed control for the Chiller System. The
Steam Turbine operating speed is controlled by a Governor Valve that is integrated with the
Chiller controls. The Governor Valve controls flow throughout the entire operating range of the
Steam Turbine. If the speed sensed by the automatic controls exceeds the maximum speed of
4500 rpm it will automatically begin closing the Governor Valve. If the speed should continue
to increase the controls will continue to send a signal to close the Governor Valve.
If the automatic speed controls should fail to slow the Turbine by closing the Governor Valve in
an overspeed condition, the software overspeed logic will de-energize the Turbine Trip Solenoid
at a programmable setpoint that is usually set 50 rpm below the mechanical trip activation speed.
A mechanical spring loaded overspeed device will trip at 110 percent of maximum design speed.
This mechanical overspeed trip mechanism will immediately close the Overspeed Trip Butterfly
Valve.
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Figure 2 – Steam Turbine
Steam Turbine Data
Manufacturer
York
Nominal design maximum operating
speed
4500 rpm
Design
Horizontal split-case, multistage
Model
KG
Steam Turbine Data
There is an overspeed trip that can be used by the Operator in an emergency. The
EMERGENCY STOP knob at the base of the Steam Turbine activates this manual trip. The
manual trip is connected to the same linkage as the mechanical trip.
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Figure 3 – Steam Turbine Emergency Stop
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University of Vermont
Chiller Generator System Unit 1 and 2
2.3
Central Heating and Cooling Plant
UVM-CP-24-SD
Evaporator
The Evaporator is a shell and tube, flooded type heat exchanger. A Distributor Trough provides
uniform distribution of refrigerant over the entire shell length. Stainless steel mesh eliminators
or suction baffles are located above the tube bundle to prevent liquid refrigerant carryover into
the Compressor. A Liquid Level Sight Glass is located on the side of the shell to aid in
determining proper refrigeration charge. The Evaporator shell contains dual Refrigerant Relief
Valves.
Figure 4 – Evaporator
2.4
Condenser
The Condenser is a shell and tube type heat exchanger, with a discharge gas baffle to prevent
direct high velocity impingement on the tubes. A separate Subcooler is located in the Condenser
to enhance performance. Dual Refrigerant Relief Valves are located on the Condenser shell.
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
The removable compact Water Boxes are fabricated of steel. Integral steel water baffles provide
the required pass arrangements. Stub-out water nozzle connections with Victraulic grooves are
welded into the Water Boxes.
Figure 5 – Condenser
Condenser Data
Manufacturer
ITT Standard
Type
Shell and tube
Water box design working pressure
150 psig
Water box tested pressure
225 psig
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University of Vermont
Chiller Generator System Unit 1 and 2
2.5
Central Heating and Cooling Plant
UVM-CP-24-SD
Steam Condenser Package
The Steam Condenser Package consists of a Steam Condenser, Single Hotwell (condensate)
Pump, single Vacuum Pump, Hotwell Condensate Level Control System, and an Atmospheric
Relief Valve.
The Steam Condenser is provided to condense steam exhausted from the Steam Turbine.
Cooling water supply for the Steam Condenser is piped from the outlet of the Condenser. The
Steam Condenser is a shell and tube heat exchanger. Steam condenses on the outside of the
tubes. Condensing water flows inside the tubes. Subcooling sections in both ends of the
Condenser cool non-condensibles (mainly air) sufficiently below the condensing temperature to
reduce the capacity of the Vacuum Pump. Cooling water end plates are provided on each end of
the Steam Condenser so that tubes may be accessed without having to disturb the water piping
connections. An Atmospheric Relief Valve protects the steam side of the system.
The Hotwell Pump is a 5 hp, 3600 rpm motor driven direct connected pump with a maximum
suction pressure of 5 psig. The Hotwell Pump is automatically controlled during operation to
remove condensate as it builds up in the Steam Condenser.
The Vacuum Pump is a 7.5 hp, 1800 rpm motor driven direct connected single stage liquid ring
type pump designed for continuous operation. As liquid moves outwards, air is drawn into the
pump, compressed and expelled through the discharge port into a Discharge Separator that
separates the water from the air. Approximately 3.5 gpm of makeup water is required to
maintain the Liquid Seal Ring while the Vacuum Pump is in operation.
The Level Control System automatically controls the condensate level in the Hotwell during
operation. The Level Measurement Transmitter senses the condensate level in the Hotwell and
sends a signal to the OptiView Control Center, which in turn sends a control signal to position
the Condensate Recirculation Valve and the Condensate Overboard Valve. The Level Control
System includes a visual magnetic Level Gauge. High Level Trip and Low Level Alarm
Switches are wired to the OptiView Control Center to provide the safety functions required.
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University of Vermont
Chiller Generator System Unit 1 and 2
Central Heating and Cooling Plant
UVM-CP-24-SD
Figure 6 – Steam Condenser Package
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University of Vermont
Chiller Generator System Unit 1 and 2
2.7
Central Heating and Cooling Plant
UVM-CP-24-SD
Power Panel
The Power Panel contains all motor contactors and circuit protectors, the Compressor Oil Pump
Variable Speed Drive, and the Control Power Transformer. The Power Panel enclosure is
installed adjacent to the OptiView Control Center. The Main Power Disconnect Switch is
mounted on the door of the Power Panel.
Figure 7 – Power Panel and OptiView Control Center
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University of Vermont
Chiller Generator System Unit 1 and 2
2.8
Central Heating and Cooling Plant
UVM-CP-24-SD
OptiView Control Center
The OptiView Control Center provides control of the entire Chiller, including Steam Turbine and
Steam Condenser monitoring. The Control Panel includes a color Liquid Crystal Display (LCD)
surrounded by “soft” keys, which are defined based on the Screen displayed at that time,
mounted in the middle of a keypad interface and installed in a locked enclosure. The Screen
details all operations and parameters, using graphical representation of the Chiller and its major
components.
Figure 8 –OptiView Control Center
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