STANDARD OPERATING PROCEDURE AND
SAFETY GUIDE FOR SHELL AND TUBE
HEAT EXCHANGER APPARATUS
(Located in Rm. B-24 Head Hall)
Prepared
June 9th, 2011
Table of Contents
\
Table of Contents ........................................................................................................................ ii
1. Scope ........................................................................................................................................2
1.1 Objective ............................................................................................................................2
1.2 Regulations ........................................................................................................................2
2. Apparatus Overview and Objective: ........................................................................................2
2.1 Apparatus overview ...........................................................................................................2
3. Hazards Evaluation and Controls:- ..........................................................................................7
3.1 Possible fire event ..............................................................................................................7
3.2 Ventilation..........................................................................................................................7
3.3 Kinetic, Thermal and Acoustic ..........................................................................................7
3.4 Electrical ............................................................................................................................8
3.6 Gauge Oil ......................................................................... Error! Bookmark not defined.
3.7 Mercury ............................................................................ Error! Bookmark not defined.
3.8 General, physical and equipment concerns ........................................................................8
3.9 Access ................................................................................................................................9
3.10 Training ............................................................................................................................9
3.11 Personal Protective Equipment ........................................................................................9
3.12 Incident Report.................................................................................................................9
4. Operation................................................................................................................................10
4.1 Qualified Personnel ..........................................................................................................10
4.2 Experiment preparation ....................................................................................................10
4.3 Lab Instructions ...............................................................................................................11
4.3.1. Instructor Responsibilities: .....................................................................................11
4.3.2. Data/Instrument Locations and Functions ..............................................................11
4.4 Operating Procedure ........................................................................................................12
4.4.1 Startup and procedure ..............................................................................................12
4.4.2 Shutdown ................................................................. Error! Bookmark not defined.
5.0 Inspections ...........................................................................................................................15
5.1 Periodic & Operational Inspections .................................................................................15
6.0 Typical Tests ........................................................................................................................16
i
B-24, Head Hall Floor Plan
Figure 1: B-24 Floor Plan, Head Hall
1
1. Scope
1.1 Objective
This standard operating procedure is intended to provide operating
instructions and safety information for the Department of Chemical
Engineering’s shell and tube heat exchanger experimental apparatus located
in B-24, Head Hall. This document is intended as a guideline and
supplement to proper training that must be provided by qualified personnel
before the apparatus is operated. The aim of this document is to ensure that
safe work practices have been developed for the heat exchanger
experimental work. This SOP is primarily concerned with the assembly,
procedure, hazards of the experiment and safety precautions that must be
taken to avoid injuries.
1.2 Regulations
This document has been developed in accordance with the Environmental
Health and Safety Office of the University of New Brunswick.
2. Apparatus Overview and Objective:
2.1 Apparatus overview
The experimental apparatus is used to measure the overall heat transfer
coefficients for a shell and tube heat exchanger using the log mean
temperature difference (LMTD) method and the number of transfer units
(NTU) method. The rate at which heat is transferred with the use of a shell
and tube heat exchanger can vary according to flow rates, temperature
gradients, and flow direction (counter or co-flow). Shell and tube heat
exchangers are commonly used in the industry because they are relatively
inexpensive and are able to combine near counter-current flow with crossflow. This combination results in a much higher heat transfer coefficient for
the shell and tube heat exchanger when compared to a pipe-in-pipe style heat
exchanger. They allow for the transfer of heat efficiently without any
mixing of the two media’s undergoing the heat exchange. This lab will help
to further the students understanding of how to optimize the amount of heat
being transferred when using a shell and tube heat exchanger.
2
The apparatus for the shell and tube heat exchanger is comprised mainly of a
base unit, for controlling the experimental conditions, and a small shell and
tube heat exchanger (l x w x h: 400 x 230 x 110 mm). The shell and tube
heat exchanger is designed for either counter-flow or co-flow operation. The
shell and tube heat exchanger has a heat transfer area of 20,000 mm2,
contains seven tubes (Stainless Steel, 6 mm diameter, 1 mm wall thickness),
four baffle plates, and an outer transparent shell (PMMA, 50 mm
diameter, 3 mm wall thickness). There are four water connectors with quick
action hose couplings to easily connect the hot and cold water supply to the
heat exchanger. The water connectors on the heat exchanger are male
connectors for the hot water tubes and female connectors for the cold water
tubes. The tubes containing the hot and cold water are connected to the heat
exchanger as shown in the picture below.
Figure 2: Shell and Tube Heat Exchanger
The apparatus can be set up to run under co-flow or counter-flow conditions
depending on how the cold water connectors are set up. At the end of each
3
connector, on the half attached to the tube, there is a temperature sensor
which sends a signal back to the base unit.
The base unit consists of all the necessary controls, indicators, and displays
for temperatures and flow rates. A picture of the base unit is shown below.
Figure 3: Base Unit
The unit is switched on using the large master switch. Next to that there is a
temperature controller for the hot water in the tank which is found behind
the base unit. The heater switch, located below the control, must be turned
for the water to be brought to the set temperature. The heater will not turn on
if the level of the water in the tank is low. This is indicated by the tank
water low indicator light, which will turn red when water needs to be
added to the tank. The hot water tank is filled with water supplied from the
building by pressing the green cold water supply valve button. The tank
should also be full before turning on the pump, using the pump switch,
which pumps hot water through the heat exchanger. The flow rates for both
the hot and cold water are controlled using the hot and cold water control
valves. The temperatures and flow rates of the cold and hot circuit are
displayed on the four display screens shown above. The display switch
4
changes the display from showing the cold circuits properties to the hot
circuits. The mixer switch, mixer speed control, computer input and the
display for the middle temperature are not used in this experiment. A
stopwatch is also required when completing this experiment. There are
more pictures displayed below for further understanding.
Figure 4: Building Water Supply Valve
Figure 5: Side of Base Unit
5
Figure 6 & 7: Temperature Sensor and Tubing connections
Figures 6 and 7 shows the connections to the base unit for the tubes and the
sensors attached to the ends of them. Figure 4 shows the building water
supply valve, which brings in all the fresh water to fill the hot water tank
and is also used to run through the cold water circuit. Figure 5 shows where
the supply water enters the system, the cold water drain tube, and the hot
water drain tube.
6
3. Hazards Evaluation and Controls:3.1 Possible fire event
The shell and tube heat exchanger experiment is not of high risk for causing
a fire. However, in the event of a fire evacuate the room immediately. Pull
the nearest fire alarm (located outside room). Should you return to attempt to
extinguish the fire, do not do so alone and make only one attempt. If
unsuccessful, leave immediately. If successful, stay at the scene and have
someone alert the Security and Traffic office (ph. # 4830) and the
Environmental Health and Safety office (ph. # 5075). Please refer to Figure
1 (B-24 Head hall floor plan) to see the locations of fire extinguishers, fire
alarm pull station.
3.2 Ventilation
Ventilation fans and ductwork are installed such that there shall be fresh air
introduced into the room and ambient air exhausted from the room at all
times the room is occupied. These fans are controlled by wall switches. If at
any time the fresh air supply or room exhaust fans are not working then
contact Facilities Management immediately (ph # 4889). The room itself is
under negative pressure causing the flow of air into the room from other
areas.
3.3 Kinetic, Thermal and Acoustic
The apparatus poses no kinetic threat under normal conditions, however the
system does pose some thermal threat due to the hot water required to run
the experiment. The hot water is heated up in the hot water tank in the back
of the apparatus. When the apparatus is turned on the water can be brought
up to temperatures around 85 (80 °C is the suggested maximum controller
setting ). To avoid potential burns, the tank should not be touched when the
experimental apparatus is in operation and for some time after it is shut off.
The hot water from the tank is pumped through tubing and through the heat
exchanger. The tubing and connectors to the heat exchanger (containing the
hot water) can become extremely hot as well and caution should be taken
when working around them. This is why only the cold water tubes should be
switched when changing from co-flow to counter-flow, as to avoid handling
the hot tubes and connectors.
The experimental apparatus does not pose any acoustic threat, however
nearby experiments may produce loud noises and if anyone partaking in the
7
experiment is made uncomfortable, then earplugs can be worn to reduce the
sound.
3.4 Electrical
The shell and tube heat exchanger apparatus is comprised of one main piece
of electrical equipment which is the base unit. The base unit is the central
control system for the experimental apparatus and consists of many separate
electrical components. The majority of the wiring is covered by a casing on
the base unit which is powered by the plug and socket shown below (20A,
208 V, 3ØY). If any work needs to be done on the unit that requires the
casing to be taken off, the system should be locked out before doing so (see
Lockout and Tag-out of Hazardous Energy). The power supply cable has a
thick insulation and therefore poses no threat if handled carefully. If the plug
needs to be taken out of the socket it will need to be gripped and slightly
twisted counter-clockwise while extracting it. Always check the apparatus
for bare, frayed or cut electrical cables before operating it. If a fuse blows or
wires become bare then the lab technician/instructor should be notified
immediately.
Figure 7: Power Supply
3.8 General, physical and equipment concerns
A fuse may occasionally blow in the apparatus when attempting to start the
pump. It will be evident that this occurred because the pump will not turn
on, because there is no flow in the hot water circuit. If this occurs then
contact the lab technician for assistance. This is more apt to happen when
the apparatus is being started up after not being used for a long period of
8
time. The cold water flow rate will vary due to building use and cannot be
prevented. The flow of cold water can range from 0~4.7 L/min and the hot
water flow ranges from 0~1.5 L/min. It is best to operate in the middle
ranges of these values.
3.9 Access
All personal in the B-24 laboratory should be preauthorized by the lab
faculty supervisor or be under the supervision of authorized personal (lab
technician or teacher assistant). No person other than the faculty member in
charge or specifically authorized personal are permitted to modify or
conduct experiments with the shell and tube heat exchanger apparatus.
3.10 Training
All individuals operating the shell and tube heat exchanger apparatus shall
be required to receive training in the proper operation and maintenance of
the apparatus and its controls. Training will include such topics as the
complete assembly, operation, disassembly, and controls for the apparatus.
Training programs shall be administered only by qualified personnel at
UNB.
3.11 Personal Protective Equipment
Following personal protective equipment is required while doing the
fluidized beds experiment:
• Lab Coat
• Safety Goggles/Glasses
Other personal protective equipment should be used in the experiment if
required to avoid any injury.
3.12 Incident Report
In the event of an injury in the lab the situation must be dealt with according
to the internal accident reporting procedure (Reference # 7901-B, Safety
Handbook). The university accident report form will be filled out within 24
hours of the accident by the person in charge of the area at the time. This
form is to be filled out for all accidents regardless of their severity. A copy
must be sent to the Security and Traffic office, the Environmental Health
9
and Safety office and to Risk Management at the Budget Office.
4. Operation
4.1 Qualified Personnel
These notes in the operation section will provide a guideline to the
individual who has been trained by qualified personnel to operate the shell
and tube heat exchanger apparatus. Only after the individual has been
trained and is confident with the apparatus set up, operation and shutdown
procedures should he or she attempt to operate the apparatus using these
notes. Do not proceed if you are not properly trained or are unsure of the
safe operation of this apparatus.
4.2 Experiment preparation
The following procedures should be followed in preparation for this
experiment, so as to avoid any accidents or malfunctions:
• Prior to turning on the system the cold water control valve should be
in its OFF position (completely turned clockwise) and the hot water
control valve should be fully OPENED (turn counter-clockwise).
• The switches for the heater, pump, and mixer should all be in there
OFF position.
• The temperature control should be set to its minimal starting point.
• A stopwatch should be made available for the experiment.
• Open the main water supply valve shown in figure 4.
• When the system is turned on, by turning the master switch, the tank
indicator light should be checked along with a visual inspection of the
water level in the heating tank. If the light is ON, or level is LOW,
then refill the tank by pressing the green cold water supply button.
The light will turn off when the tank is full. It should also be
monitored visually to insure it does not overflow.
• The starting temperature chosen for the hot water to be run at (~ 40°C
would be sufficient) should be set. The heater can then be turned on.
Approximately 10 minutes will be required for the water to warm up
to the set temperature. When it reaches the set temperature, the Green
Light on the temperature controller will turn OFF. This should be
done before the experiment begins.
10
• The pump will also need to be tested to insure it is working. If the
pump does not turn on, or there is no measureable flow when it is
activated, then contact the lab technician for assistance.
• If there is a fair amount of bubbles visible in the heat exchanged then
the heat exchanger should be removed from the apparatus (by
unscrewing the four knobs holding it in place). Then the cold water
control should be opened to allow water to flow through the heat
exchanger. While is occurs the heat exchanger should carefully be
tilted back and forth to remove the bubbles.
4.3 Lab Instructions
4.3.1. Instructor Responsibilities:
The apparatus script/manual provided with the apparatus and this document
(SOP) should be read and understood. These documents provide all the
necessary information regarding the apparatus components specifications,
startup procedure, operation, hazards involved & safety precautions to be
taken while using this apparatus. The lab instructor shall remain in the room
while the experiment is in progress. After the student group has assembled
and before any explanation has begun, the instructor shall relay all safety
precautions and hazards as outlined in Section 3. Inform the students that
they must contact the instructor should any problems or concerns arise
during the experiment. Make the group aware of the fire extinguisher
locations, fire alarm pull stations, phone and exits. Any student from the
group missing any personal protective equipment shall not be allowed by the
instructor to enter the laboratory B-24 and shall not proceed with the
experiment.
4.3.2. Data/Instrument Locations and Functions
• Temperature Sensors. The sensors are located on the tube side
connectors to the heat exchanger. They send signals to the base unit to
be displayed.
• Digital displays. The digital displays are located on the face of the
base unit and show temperatures and flow rates for the hot and cold
circuit.
11
• Stopwatch. The stopwatch is found in the locker assigned for the
experiment and should be made available for the students at the
beginning of the experiment.
4.4 Operating Procedure
4.4.1 Startup and procedure
After preparing for the experiment and following the steps listed in section
4.2, the instructions below must be followed to perform the experiment.
The effects on the overall heat transfer coefficient, in the shell and tube heat
exchanger, is analyzed by completing trials during steady and unsteady
conditions, changes over measured time intervals, and by changing the flow
configurations.
The first set of trials should be completed with the heat exchanger set up for
counter-flow operation. For this the cold water outlet tube must be
connected next to the hot water inlet connection. The cold water inlet tube
must therefore be connected next to the hot water outlet connection. The
tubing can be followed back to the base unit to check which tube is for the
inlet and which is for the outlet. The connectors are quick action and easy to
use. If they need to be switched refer to figures 8 and 9 for guidance. The
heater should already be turned on at this point and the water should be
warmed up to around 40°C to begin the trials. If the water has not already
been preheated then follow the instructions found in section 4.2. Once
everything is ready the first set of trials can begin.
• First there should be two set flow rates, a high and a low, for both the
cold and hot water to give a total of four combinations. The cold water
has a wider range of flow rates, so the low can be set around 1 L/min
and its high can be around 2 L/min. The hot water flow rate has a
smaller range so the low can be set around 0.5 L/min while the high
can be around 1.2 L/min.
• When the flow rates are set it may take a minute for the system to
reach steady state. When this is reached the values of the temperatures
can be read off the displays and recorded. The display switch will
have to be turned in order to get values from both the hot and cold
circuit. This should be done quickly to insure the results are taken at
roughly the same time.
• The flow rates will fluctuate during regular operation, mostly the cold
water flow rate will do this. This is because the building water supply,
12
where the cold water comes from, is always in use and therefore will
cause the flow to constantly change.
• The flow rates will have to be constantly monitored and recorded over
the trials and an average flow rate will have to be determined during
the trial period.
The second situation only includes one trial; this is the transient to high
temperature trial. For this the stopwatch will be required. Both flows
should be set to the high flow rate used in the last trial.
• The temperature controller is set from 40°C to 70°C, however the
instant this is changed, data will need to be recorded.
• The stop watch is required for this trial, after the temperature has been
changed a designated person will have to announce when every time
interval has passed. This is a set and constant time interval and could
be every 30 seconds or every minute.
• After each time interval all the data for the hot and cold circuits will
have to be recorded. This should be done in less than 10 seconds to
keep the data accurate.
• The flow rates should be recorded as constant (averaged) over the
time period.
• The data can stop being recorded when the hot water reaches within
2°C of the set temperature.
Four more trials at 70°C can be completed following the same method as the
countercurrent trials at 40 °C (first set that were explained). These are the
trials for steady operation at high temperatures. When changes are made
time should be given to allow the system to stabilize before recording any
data.
The following trial is completed using the stopwatch. This trial is for taking
measurement for the transient from counter-current to co-current flow.
The high flow rates set in the first trials are again used for this one. The
temperature controller is left at 70°C.
• The instant the changes are made from counter-current to co-current
the stopwatch needs to be started along with the immediate recording
of data.
• To make the change, only the cold water tubing needs to be switched.
To do this the connections are easily disconnected by slightly pushing
13
on the easy release connection piece which is connected to the heat
exchanger. Pictures are shown on the following page for better
understanding. The change should be done quickly to achieve good
data. However not too quickly to avoid causing damage to the
equipment. If it does not go well then this step can simply be repeated.
Figure 8 & 9: How to Release Connectors
Note: The hot water connectors should not be changed during the
experiment. If they need to be disconnected for other reasons the release is
done by slightly pulling on the same piece shown above (opposed to pushing
it in) which is found on the hot water tube side. This should not been done
forcefully, if it does not disconnect easily then ask a lab technician for
assistance.
• When the connection is made, the temperatures for the hot and cold
circuits should be record. This transient takes place quickly so the data
will have to be collected as quickly as possible. Therefore try to get as
many measurements as best can, with the time of each recorded
temperature set. The average flow for both circuits over the time
period should be observed and recorded as well.
After the transition from counter-current to co-current has been completed,
and the system has reached steady state, four trials for steady operation at
high temperature can be done. These are completed following the same
steps as the first four trials explained above but at a temperature of 70°C and
using co-current flow. Further combinations can be tested if desired by the
individuals completing the trial. When changes are made time should be
given to allow the system to stabilize before recording any data.
14
After this is done and the experimental data collection is completed the
apparatus can be shutdown.
4.4.2 Shutdown
After the final trial has been completed theses steps must be followed.
• Insure that the pump switch, heater switch, and even the mixer switch
are in the OFF position. After that, the master switch can be turned
OFF.
• The cold water flow control valve should be turned completely OFF
(by turning it fully clockwise), while the hot water flow control valve
should be left OPENED (turned counter-clockwise)
• The building supply valve shown in figure 4 should be CLOSED.
• If the device is not to be used for a while the hot water tank should be
drained by opening the drain valve shown in figure 5.
• Any water that may have spilled or leaked out should be cleaned up
and the stopwatch should be put away.
5.0 Inspections
Inspections at regular intervals will be performed on the apparatus to ensure
that the apparatus is kept in a safe and well maintained condition. Regularly
check for bare & cut electrical wires in the apparatus.
5.1 Periodic & Operational Inspections
Visual inspections are the responsibility of the person who is conducting
experiments on a regular basis with the Heat Exchanger apparatus and
should be carried out each time before operating apparatus. A complete
periodic inspection of the apparatus shall be performed by the person who is
conducting experiments on a regular basis with this apparatus. This will alert
the lab faculty supervisor of any deficiencies in the apparatus. The
deficiencies such as those listed below shall be examined during both the
periodic & operational inspection. The lab faculty supervisor will determine
if the deficiencies will affect the safe operation of the apparatus.
15
Deficiencies
a.
b.
c.
d.
e.
Worn, cut or bare electrical wires
Any leaks in the tubing, connectors, tank, heat exchanger, base unit
Check to insure water is able to flow through the apparatus
Pump operation
Any damage to the overall apparatus
6.0 Typical Tests
The actual test procedure will be outlined in the lab script as issued by the
professor. The trials usually consist of four trials with altering flow rates at a
low and high temperature. This is done while the heat exchanger is set up for
counter current flow; the transient from the lower to higher temperature is
also studied. The shell and tube heat exchanger is also changed to co-flow.
Typically data is recorded during this change. The steady operation at high
temperature during co-flow is the final aspect usually studied during this
experiment. The temperatures and flow rates read from the displays are
recorded throughout each trial. The data recorded is typically used to
determine the overall heat transfer coefficient for each scenario using both
the log-mean temperature difference method (LMTD) and the number of
transfer units method (NTU). The results should contribute to furthering the
understanding of how to maximize heat transfer in a shell and tube heat
exchanger. These concepts are essential knowledge for operating shell and
tube heat exchangers which are commonly used in the chemical engineering
industry.
Refer to the lab script for theory and experimental information.
16