engine room ventilation summer2015
TRANSCRIPT
Engine Room Ventilation
Prof. Dr. Ali HammoudBAU-2015
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Generator Room
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المقدمة
ابأصح الى , فيه الفضل يعود والذي اللقاء هذا في الكرام والمهندسين بالحضور نرحب. لبنان في الكهربائية المولدات وتجار المبنية العقارات وتجار
لـيـا ــاع الصوت رفع الى فعنــا يـد , فـقـط الـنـفـعـيـة المصلحة على المبني , هؤالء سلوك إن. نمـتـهـن وحـده الـذي الـعـلـمـي بإســـلــوبــنـا بوجــههـم "
"كهربائيـا "مولدا يـبـنـيـه الذي للـمـنـشـأ وقـدم لبنان في العقارات تجار أحد تكرم إذ هــمــه اتالمولد وبائع . فيه المولد لـيـدفــن العقار في الـمـيـّـتــه الزوايا إحـدى يـخـتار فـإنـه
"شروطــا تتطلب المولد غرفة أن "علمــا ؟ الــسـنـة في باع "ا مـولــد كــم : الوحـيـد علمية ال وأن يجب كما دوره المولد يؤدي حتى - والـتهـوئة المســـاحــات حيث من - خــاصــة
. بسرعة االفتراضي عمره يستهلك اجهاتحت التي األساسية المبادئ بعض ومبسط موجز بشكل لكم سنقدم المحاضرة هذه في. الشأن بهذا الحلول و المشاكل من "بعضا موجز بشكل لكم سنعرض كما المولدات غرف
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شروط السالمة العامة لغرف المولد والمازوت والشودیرات (2005)
)شوديرات,مولد,مازوت(أبواب مقاومة للحريق تفتح الى الخارج –).شوديرات,مولد,مازوت(وكشف للحريق انذارنظام –).شوديرات,مولد,مازوت(احتياطية للطوارئ انارةنظام –).شوديرات,مولد,مازوت(ويدوي الي اطفاءنظام –.)وديراتش,مولد,مازوت(يمنع وضع أي تجهيزات كهربائية غير تلك الخاصة بالغرفة ومنع استعمال االنارة المتدلية–).مازوت,واحدة أو أكثر تنفيسة( تهوئةتجهيز أنابيب –.)شوديرات,مولد,مازوت( تهوئة–).شوديرات,مولد(في بفلترالمجاورة بمترين مجهز االبنيةأعلى من داخون–.الطوابق السفلية اوفي الطابق األرضي بهاتخزن المحروقات في غرف خاصة –).مازوت(ملم 3سماكة صفائح خزانات المازوت ال تقل عن –).مازوت(مازوت في الغرفة الواحدة ليتر 10000مجموع سعة الخزانات –).مازوت(اليةلتجميع المازوت الفائض مجهزة بمضخة جورة–
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شروط السالمة العامة لغرف المولد والمازوت والشودیرات
).مازوت(تجهيز الخزانات بمؤشر لتحديد كمية المحروقات المختزنة–).شوديرات,مازوت(صمام قطع –).مازوت(تأريضبواسطة مأخذ باالرضيةيجب وصل الخزانات –).مازوت(جهاز لوقف الدفق خارج غرفة التخزين–).شوديرات,مولد,مازوت(ترك ممرات كافية للصيانة –).شوديرات,مولد,مازوت(عزل +سم 15 اوسم 20سماكة جدران الغرف –).شوديرات,مولد(سم 20عتبة بعلو –.في الطوابق السفلية أو األرضية فقط بهافصال تاما ويسمح والشوديراتتفصل غرف المولد والمازوت –).مولد(المولد مركز على قواعد فنية لمنع االرتجاج–).مازوت(عتبة بعلو يمنع تسرب كمية المحروقات في أكبر الخزانات أو نصف الكمية في مجموع الخزانات–).شوديرات,مولد,مازوت(تجميع المازوت بجورةمجاري في غرفة المولد متصلة –).مولد(برميل للزيت المستعمل–.من مساحة الغرفة فراغ% 60تأمين –.سم 220ارتفاع غرفة المولد ال يقل عن –
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Why design ??
The upcoming data and images’ source is the Beirut Fire Department
Fire
Four things must be present at the same time in order to produce Fire:
Fuel Oxygen Heat Sustaining Chemical Reaction
0
20
40
60
80
100
Num. of Fire
83
64
91
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2006200720082009
Yearly average: 78.5 per year FIRES CAUSED BY “bad ” of generator rooms & Electrical Panels
Note that Beirut region has the smallest electricity cut‐off period in Lebanon.
Still the number of fire accidents caused by generators is dramatically high.
In Beirut
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Causes of Fire in Generator Rooms
1‐ Not following the safety regulation , codes & standards2‐ Bad ventilation (Overheating) & Oil leakage of the engine can
cause burning3‐ No automatic or Manual fire fighting system4‐ Presence of Electrical panels in the generator room 5‐ Bad Maintenance etc..
Our main concern is the Bad ventilation (Overheating) in closed area
Gemmayzeh 26/10/2008
.الطوابق السفلية اوفي الطابق األرضي بهاتخزن المحروقات في غرف خاصة
غرفة يمنع وضع أي تجهيزات كهربائية غير تلك الخاصة بال.)شوديرات,مولد,مازوت(المتدلية االنارةومنع استعمال
Video showing“Natural Ventilation” of electrical generators in addition to unsafe cabling
Diesel Tank right on top of the generator !
Control panel right next to generator !
Damaged area nearly 4m radius
الطريق الجديدة 05‐03‐2011
Smoke extraction fans
Diesel tanks close to water tanks and electric cables
Msaytbeh 31‐7‐2009
That’s why it is obviously important to set up rules, standards and regulations for generator rooms in the country.
Ali Hammoud, PhD
Electrical Panel
Ali Hammoud, PhD
Ali Hammoud, PhD
Ali Hammoud, PhD
Control panel right next to generator !
Ali Hammoud, PhD
Engine room ventilation (Heat removal by air).
Objectives:To provide a suitable environment that permits 1. The Generator to operate properly during its
service life. 2. The operators to work comfortably and
effectively. 3. Prevent Engine Overheat and Shut Down of
System.33
Outlines Factors that should be considered in designing the room
ventilation.1. The heat dissipated from the engine & alternator in the
room.2. The amount of air required to remove the dissipated
heat from engine to maintain a suitable room temperature not to exceeding 120F.
3- The amount of air needed for engine combustion.4- Fan size to supply the total amount of air required. 5- The total area of louvers & grilles.6- Engine back pressure calculation.
Hot air out from the
room
Cold air entering the room
Fresh air for cooling the radiator
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This arrangement is not a typical one. Usually, the Radiator Fan mounted on the Engine discharges the whole air quantity required to ventilate the room. But due to bad location of the engine and the sudden change in the direction of the duct at the outlet of the axial fan, it may result in reduction in flow rate due to increases in duct resistance .The reduction in flow rate may lead to overheating the engine and also to shut down the engine. An additional fan in series might be installed to assist the Radiator Fan in overcoming the pressure losses in the air path. Care should be taken when installation the second fan in the path or at the end of the duct. This method is satisfactory as long as the designer understands its strengthsand weaknesses . It is recommended to use identical axial fan having the same performance .Another small fan installed in the room to remove the heat from the generator room.
21,168 Cfm
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H.EX
Remote Mounted Radiator Cooling• The radiator can be mounted remotely (not mounted directly at
the engine). The remote/close system uses the same radiator typeexcept it is mounted outside the building, but within closeproximity to the Generator set.
• The remote radiator may be mounted either vertically orhorizontally. In general, the radiator will have an electric fan toprovide cooling air and a heat exchanger to transfer the heat toradiator . It is also possible to utilize the engine mounted coolantpump to provide coolant water flow if the head of the pump deliverenough pressure to overcome losses.
• If a new pump is installed the water flow rate should not exceedthe capacity of the engine pump.
• The piping system friction loss between engine and radiator must be calculated .
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Routing Considerations & types(Generator Set with Remote Radiator) Maintaining recommended air temperatures in the engine room is impossible without proper routing of the ventilation air. The following principles should be considered when designing an engine room ventilation system :
• Ventilation air should be exhausted from the engine room at the highest point possible, preferably directly over the engine.
• Avoid short‐circuiting between air inlets and outlets .
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• Avoid ventilation air supply ducts that blow cool air directly toward hot engine components. This mixes the hottest air in the engine room with incoming cool air, raising the average engine room temperature. This also leaves areas of the engine room with no appreciable ventilation.
• For engines that draw combustion air directly from the engine room, the routing should provide the coolest possible air to engine/turbocharger inlet.
• Provide Sound Attenuators at Air Intake & Discharge path to maintain acceptable noise level outside the Generator Room.
• Supply Air to the Room shall be from the Alternator Side.
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Routing Considerations & types
Ventilation Type 1
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Ventilation Type 2
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Ventilation Type 3
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Ventilation Type 4
Short cut
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Multiple Engines
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Incorrect air flow distribution
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Engine Room VentilationNotes
1. Room pressure should be slightly higher than atmospheric pressure to ensure complete combustion.
2. Consider the heat generated by other equipments installed in the engine room.
3. Consider the highest safe temperature that other temperature sensitive equipments can be subjected to ,such as electric equipments.
4. Engine room temperature should not exceed 48°C (120°F). 53
Required Ventilation Airflow in “engine room”
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FairCombustionTCp
PQV
)(
Qv = Volume Flow Rate in m3/hrP = Heat To Be Extracted in KWρ = Air Density in Kg/m3 at air temperature
38°C (100°F). The density is equal to 1.099kg/m3 (0.071 lb/ft3)
ΔT = Temperature Difference Between DesiredIndoor & The Design Outdoor Dry Bulb in oK.
Cp = Air Specific Heat Capacity (0.017 kW xmin/kg x °C), (0.24 Btu/LBS/°F)
Engine is On
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Engine is off
3
( )(
32 1 155.7 m /min1.099 0.017 11
1820 53400.071 0.24 20
V
v
v
P KwQ FCp T
Q
Q CFM
The required heat to remove heat dissipation from engine (shut)
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Combustion air quantity & Factor
• Approximate consumption of combustion air for a diesel engine is 0.1 m3 /brake kW.min (2.5 ft3/bhp. min) . ( Manufacturer catalogue )
• F = Routing factor based on the ventilation type discussed previously.
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• For a 400 KVA type FG Wilson generator. Perkins (Radiator‐Mounted Type).
• To calculate the required air flow rate for cooling the generator room , assume a Type 1 routing configuration.
• From the catalogue ,The heat rejection is 1820 Btu/min (32kW ), and the permissible rise in engine room temperature is 20°F (11°C).
• Note: Max engine room temperature is 120°F (48 °C)
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Engine Room Ventilation Example
Generator DataFG Wilson catalogue :400 KVA (320 kW),a) Air flow required for cooling the generator radiator is:
21168 CFM (599.4 m3/min).b) Air flow required for combustion, is :
833 CFM (23.6 m3/min)c) The heat rejected by radiation from each generator (engine plus
alternator) is 1820 Btu/min ( 32 kW) d) The generator dimension L x w x h ( in meters) is :
3.5 m X 2.7 m X 2.15 m• Now, based on these data(a & b ) we can size the intake grille & ( c) is
used to calculate the required air flow for cooling the generator room and fan sizing.
60Perkins 2206A‐E13TAG2/5
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Notes• It is to be clarified that the 21,168 cfmindicated in the Catalogue has several components:Ventilation to remove heat rejected into the Room (6,173 cfm) + Ventilation required to remove heat rejected fro the Radiator mounted on the Engine + miscellaneous requirements.
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Solution: • The estimated ventilation flow rate
required to remove the Heat Rejected from Engine into the Room, including combustion air.
63CFMQ
Q
airCombustionTCp
KwPQ
v
v
V
61738332024.0071.0
1820
/minm18023.611017.0099.1
32
1))((
3
Remote Radiator
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Engine is off
CFMQ
Q
TCpKwPQ
v
v
V
53402024.0071.0
1820
/minm7.55111017.0099.1
32
1)((
3
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Heat radiated by the generator
HRG = Heat Radiated by the Generator (kW), (Btu/min) P = Generator Output at Maximum Engine Rating (kW) η = Generator Efficiency .
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9.56)1()Btu/min(:
)1()(
PHRGUnitsUSIn
PkWHRG
If no data is available from catalogue:
Example
• 320 kW standby generator set has a generator efficiency of 92%. The generator radiant heat for this generator can be estimated as follows.
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kWPHRG 6.25)92.01(320)1()kW(
min/14569.5625)Btu/min( ButHRG
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gy gRemote Mounted Radiator Cooling
& Energy saving
The heat rejected from water radiator is used to heat the water heater as can be seen in the following figures
Generator Room Louver size
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• Openings with louvers should be twice the area of an unobstructed opening to provide proper air flow.
2
VQA
1‐Suction Face velocity Vs=275 ft/min2‐The Delivery Flow Velocity Vd=500 ft/min
Fan selection & size• The selection of fan size is usually determined by
ventilation air volume, pressure requirements and space limitations within the engine room.
• In reality Fan sizing involves much more than just selecting a fan that will deliver the airflow volume needed to meet the cooling air and combustion air requirements.
• It requires a basic understanding of fan performance characteristics and ventilation system design parameters .i.e pressure drop in duct and fittings to select a fan operate at BEF or nearly so.
• Refer to lecture chapter 7 ( Fan selection) Dr. Hammoud
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Program
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Ventilation Requirements to prevent temperature rise above recommended limit
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Back pressure of an exhaust pipe system
I. Formula:
The following formula is used to calculate the back pressure of an exhaust system
P=CLRQ2 / D5
P=back pressure (in Hg)C=0.00059 for engine combustion air flow of 100 to 400 cfm=0.00056 for engine combustion air flow of 400 to 700 cfm=0.00049 for engine combustion air flow of 700 to 2000 cfm=0.00044 for engine combustion air flow of 2000 to 5400 cfm
L=length of exhaust piping in ft
for elbows the equivalent length of straight pipe is calculated as follows:
Length (ft) 45 elbow = 0.75 x diameter (inches)Length (ft) 90 elbow = 1.33 x diameter (inches)
R= Exhaust density in pounds per cubic foot
R= 41.1/(exhaust temp F + 460 F)
Q=exhaust gas flow in ” cfm”
D=inside diameter of exhaust pipe in “ inches”
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The data shown in the accompanied table is for the same generator.Now suppose we need to check if the 4 inches pipe diameter is used for exhaust gas will be satisfactory ?The length of the pipe is 100 ft with 2 , (45 deg elbows) & 4 (90 deg elbows) .
Perkins 2206A‐E13TAG2/5
II- Example Back pressure calculation for MF 100 KVA
1) Engine technical data: From the corresponding catalogueMax . Allowable back pressure =3 in HgExhaust gas flow =2281cfmCombustion air flow =833 CfmExhaust gas temperature = 1166 F (630 °C)
2) Total length for 4” exhaust pipe:No of 90° elbows =4No of 45° elbows =2Equivalent length in ft(4”) =2x0.625x4”+ 4x1.33x4” =22ftLength of straight pipe (4’’) =60 m inside shaft
=5m horizontal (as quantified on drawings)=216ft
Total EFFECTIVE length (4’’) =238.6 ft
3) Back pressure calculation:R =41.1/(1166+460) =0.025Q =2281 cfmC =0.00049Total Effective length =238.6 ft(Pressure drop 4’’) =0.00049x238.6x0.025x[2281)]2 /(4)5
= 14.5 in HgP total = 14.5 ›3 in Hg (rejected,a larger diameter shall be
selected)
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Example : for 6” diameter pipe, The Pressure drop in ft for 90 Elbow = 16 in /12 =1.33 ft x 4=5.32 ft
Le/D
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Transformer room
ventilation
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Example calculation of Transformer room ventilation in basementDesign Parameters:
Room area = 147.0 m²Room height = 4.2 mRoom volume = 617.4 m³Temperature difference ∆T = 7°C (55°C – 48°C)Number of transformer (1500 kVA) = 6 Nos.Heat dissipation for each transformer = 19.0 kWTotal heat dissipation = 114.0 kW
Forced mechanical ventilation shall be proposed as follows:
Fan air flow (IN LPS) =
=3 Nos. makeup air fans (2 duty + 1 standby) are provided each having capacity of 14000 cfm.All the above extract and makeup air fans shall be controlled through BMS.
Transformer room ventilation
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Number of air change for some practical
Application
Fire Pump Room Ventilation Ventilation rate for Fire Pump Room shall be minimum 10 ACH during fire mode and individual air conditioning during standby mode.
Generator Room Ventilation Ventilation rate for Generator Room shall be minimum 6 ACH during fire mode.
Fire Command Center Ventilation Ventilation rate for Fire Command Center Room shall be
minimum 10 ACH during fire mode and individual air conditioning during standby mode.
Test rig
2011
87
Collector
Circulator pumps location
Circulator pumps set +accessories
Heat exchanger
Heat exchanger
Heat exchangers
Supply & returns pipes
98
THANKS