How to calculate the specific fuel consumption of Power plant??

Specific Fuel Consumption (SFC) in Power Plants refers to the amount of fuel required to generate a unit of energy output. It is a key performance metric used to assess the efficiency of different power generation systems.

Specific fuel consumption (SFC)= Fuel consumption in kg/hr / Power generation in Kwh

Specific fuel consumption (SFC)= Specific steam consumption (SSC) / Steam to fuel ratio (SFR)

Factors affecting the Specific fuel consumption:

1-Steam consumption of the Turbine: Higher steam consumption of steam Turbine leads to more Specific fuel consumption (SFC).

2-Main steam parameters like pressure & temperature: Should be always on higher side but within design limit.

3-Boiler efficiency: High efficiency boilers consumer lesser fuel and hence Specific fuel consumption (SFC) will be on lower side.

4-Turbine efficiency: High efficiency Turbines will have higher out put on lesser input, hence Specific fuel consumption (SFC) of such Turbines is LESS

5-Fuel type & quality: High GCV fuel firing power plants will have lesser Specific fuel consumption (SFC).

6-Boiler operator competency: Efficient Operation of the Boiler, Turbine and other power plant equipment depends on the skill & competency of the operators.

7-Plant load factor: Operation of the Power plant units on higher loads or optimised loads leads to lower Specific fuel consumption (SFC) & Vice Versa, that is operation of plant on partial loads results into more fuel consumption and hence leads in more Specific fuel consumption (SFC).

8-Atmospheric conditions: Atmospheric conditions like temperature, pressure & humidity play a very vital role on achieving best efficiency of power plant equipment.

Specific fuel consumption (SFC) is also termed in terms of heat rate.

Heat rate = Energy consumed in kcal/ Power generation

It is measured in terms of kcal/kwh

Specific fuel consumption (SFC) is different for different fuels, fuels having higher heating value or calorific value will have lesser Specific fuel consumption (SFC) & fuels having lower calorific value will have higher specific fuel consumption.

It’s always recommended that Specific fuel consumption (SFC) should LESS.

Power plants having lesser Specific fuel consumption (SFC) are in more profit.

How to calculate the specific fuel consumption???

Specific steam consumption (SSC) is the amount of steam consumed by Turbine is always lesser to achieve lesser Specific fuel consumption (SFC). It’s measured in kg/kwh or MT/MW.

Similarly, Stam to fuel ratio (SFR) is the amount of steam generated on burning 1 MT or 1 Kg of fuel. It’s measured in kg/kg or MT/MT.

Examples:

1-Calculate the specific steam consumption of a 50 MW thermal power plant, which consumes around 960 MT of coal to generate 1200 MW power.

Given data,

Power generation = 1200 MW

Fuel consumed = 960 MT

Specific fuel consumption (SFC)= Fuel consumption in kg/hr / Power generation in Kwh

Specific fuel consumption (SFC)= 960/1200 =0.8 kg/kwh or 0.8 MT/MW

2-A 225 MW Thermal power plant’s steam turbines Specific steam consumption (SSC) is 3.5 MT/MW and it’s Boiler’s Steam to fuel ratio (SFR) is 4.5. Calculate the specific steam consumption of that plant

Given data,

Specific steam consumption (SSC) = 3.5

Stam to fuel ratio (SFR) = 4.5

Specific fuel consumption (SFC)= Specific steam consumption (SSC) / Steam to fuel ratio (SFR)

Specific fuel consumption (SFC)= 3.5/4.5 =0.78 Kg/kwh or 0.78 MT/MW

Indian Boiler Regulations-2024 Publication

3-A Boiler consumes 25 MT of bio mass to generate 55 MT of steam per hour at pressure 67 kg/cm2 and temperature 490 deg C, which is used to run the 12 MW condensing Turbine. What would be the specific fuel consumption of this plant?

Given data,

Fuel consumption = 25 MT

Steam generated = 50 TPH

Power generation = 12 MW

Steam to fuel ratio (SFR) = Steam generated per hour / Fuel consumed per hour

Steam to fuel ratio (SFR) = 55 / 25 =2.2

Specific steam consumption (SSC) = Steam consumption by Turbine TPH / Power generated in MW

Specific steam consumption (SSC) = 50 / 12

Specific steam consumption (SSC) = 4.16 MT/MW

Specific fuel consumption (SFC)= Specific steam consumption (SSC) / Steam to fuel ratio (SFR)

Specific fuel consumption (SFC)= 4.16 / 2.2 =1.89 MT/MW

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12-troubleshooting guide for Boiler Feed Pumps (BFP)

 

                           

                       12-troubleshooting guide for Boiler Feed Pumps

SL No.	Problem	Root cause	Remedy/Action to be taken
1	High bearing vibrations   What are the reasons for high bearing vibration in Boiler feed pump (BFP)	More clearance in bearing	Maintain bearing clearance within the limit as recommended by OEM
		Contaminants/burs in oil	Replace the oil
		Pump operation in re circulation mode for long time.	Operate the pump at the flow > 30% of rated capacity Pump should not be operated more than 30 min in recirculation mode
		Miss alignment for axial vibrations	Check & correct the alignment
		Looseness in foundation bolt or coupling bolts for vertical vibrations	Tighten the bolts
		Imbalance for horizontal vibrations	Check & conduct balancing test at OEM shop
		Over load operation	Operate the Turbine at or within its maximum capacity
		Looseness in impeller	Inspect the pump thoroughly & rectify the errors in impeller fitment
		Malfunction of the vibration sensor	Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.
2	High bearing temperature (Journal)   What are the reasons for high bearing temperature in BFP?	Low lube oil level	Check for any leakages, if there arrest the leakages Top up the oil.
		High lube oil temperature	Check for cooling water flow, remove the blockages if any.
		Over load operation	Operate the pump at or within rated flow
		Less clearance in bearing	Maintain bearing clearance within the limit as recommended by OEM
		Malfunction of the temperature sensor	Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.
3	Cavitation/abnormal sound   What are the reasons for cavitation in Pumps?	Low suction pressure	Check the reason for low suction pressure & Normalise
		High feed water temperature at pump’s suction	Reduce the steam flow to deaerator & maintain the suction temperature as pre-design pressure. If pump suction pressure is low, it may reach the vapour temperature leading into steam formation inn pump.
		Low deaerator level	Normalise the deaerator flow by increasing make up water or process return condensate.
		Low deaerator operating pressure	Increase & maintain the Deaerator pressure as per rated pressure
		Low suction water	1.Check for suction valve throttling & increase the suction water flow 2.Check for clogging of pump strainer due to any foreign materials.
		High flow	Reduce the flow & maintain as per OEM design.
4	More Balance leak off pressure   What is the reason for more balance leak off pressure in BFP?	Worn out balance discs	Inspect & replace the discs
		More clearance in balance & counter balance discs	Inspect & adjust the clearance as per OEM manual
		More suction pressure	Maintain the suction pressure as per OEM recommended
		Blocked balance leak off pressure impulse line	Check & clear the line Read>>>Boiler feed pumps SOP
		Higher pump discharge pressure	Maintain the discharge pressure as per OEM recommended
		High discharge flow	Maintain the discharge flow as per OEM recommended
		Faulty pressure gauge	Replace the pressure gauge
5	Low Balance leak off pressure   What is the reason for less balance leak off pressure in BFP?	Less clearance in balance & counter balance discs	Inspect & adjust the clearance as per OEM manual
		Improperly fitted balance discs	Inspect & adjust the clearance as per OEM manual
		Low suction pressure	Check & increase the suction pressure
		Low discharge pressure	Check & ensure the correct discharge pressure
		Leakages in balance leak off line	Arrest the leakages
		Faulty pressure gauge	Replace the pressure gauge
6	Pump overheating   What is the reason for pump over heating?	High feed water temperature	Maintain the feed water temperature as per design
		Operating the pump at higher flow	Optimise the discharge flow
		Operating the pump at flow < 30% of rated	1.Increase the flow beyond 30% 2.Do not operate the pump with discharge valve closed for long time.
		Low suction flow	Check the strainer & clean Check the suction valve & ensure it’s open 100%
		Cavitation	Ensure suction pressure & temperature are as per design
		Bearing failure	Replace the bearing or maintain the clearance
		Continuous operation of the pump	Follow pump change over schedule.  Boiler feed pumps SOP
		Internal rubbing due to improper thermal expansion	1.Ensure uniform expansion of pump.   2.Do not start pump as soon as hot water induced into it. Allow it for some times for uniform thermal expansion.
7	Journal bearing failure   What is the reason for BFP pump bearing failure??	No lubrication	1.Ensure proper oil level. 2.Follow lubrication & lubricant replacement schedule.
		Insufficient cooling & operation of the pump at higher bearing temperatures	1.Ensure bearing temperature is in the range of 50 to 70 deg C. 2.Ensure proper cooling water is flowing in & out of the bearing cooling jacket.
		Operating the pump at lower speed for long time	Ensure the pump will be operated at speed >80% to ensure proper splitting of lubricant oil to bearing liners
		Starting of the pump at lower speed	Always start the pump at speed reference > 50% Ensure pump will attain its 50% speed (1500 rpm) in initial 10-12 seconds, this will protect the bearing from lack of lubrication at initial lower speed.
		Frequent start & stop of the pump	Ensure pump will not be started or stopped frequently
		Starting of the pump with discharge valve opened	Never start the pump with discharge valve open to avoid sudden jerk load to the pump, which not only damages the bearing even harms pumps internals, coupling & motor
		Stopping of the pump with discharge valve opened	Never stop the pump with discharge valve open to avoid sudden jerk load to the pump, which not only damages the bearing even harms pumps internals, coupling & motor Boiler feed pump SOP
8	Insufficient discharge flow or pressure   What is the reason for low discharge or low discharge pressure from Boiler feed pump?	Pump is running on partial load or lesser speed	Increase the speed
		Discharge valve throttled	Ensure 100% opening of the discharge valve
		Suction valve throttled	Ensure 100% opening of the suction valve
		Air lock	Ensure proper priming of the pump. Keep open drain/vent provided at suction strainer for 3 sec.
		ARC (Automatic recirculation) valve stuck or passing	Servicing of the ARC valve
9	Frequent tripping of pump during start up   Why does the pump trip during start up?	Discharge valve Open	Close the discharge valve & start the pump
		Pump jam	1.Ensure proper lubrication 2.Ensure uniform thermal expansion
		Electrical related problems	Check at Motor & Panel side and rectify the identified problems
10	Excessive Noise & Vibration   What are the reasons for excessive noise & vibrations in pumps?	Cavitation in pump	Ensure suction pressure & temperatures are normal
		Pump air lock	Ensure proper priming of the pump
		Bearing damage/worn out	Inspect and replace if needed
		Internal rubbing	Inspect & replace damaged internals
		Pipe lines vibrations	Inspect supports & rectify if required
11	Mechanical seal leakage/Gland leakage   What are the reasons for Mechanical seal failure in pumps?	Improper installation	Check & reinstall the seals
		Seals parts damaged	Check the root cause & replace the damaged parts
		Frequent start & stop of the pump	Ensure pump will not be started or stopped frequently
		Worn out shaft sleeve	Replace the sleeve
		Jerk loads on seals	Ensure discharge valve is closed before starting or stopping of the pump
12	Pump consuming more power   What are the reasons for more power consumption by Boiler feed pumps?	Automatic Recirculation Valve (ARC) passing	Get done the overhauling of valve
		Bearing friction	Maintain required clearance in bearing
		Internal rubbing	Replace the worn-out parts
		Lesser efficiency of coupling & motor	Replace the worn-out couplings Verify motor load & efficiency
		Higher flow	Ensure pump is delivering flow as per design
		Lower pump efficiency	1-Check pump hydraulic power 2-Check fluid temperature & suction pressure and ensure both are as per design. 3-Ensure pump’s discharge pressure is as per design

 

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