Showing posts with label Efficiency & performance. Show all posts
Showing posts with label Efficiency & performance. Show all posts

How to calculate the quantity of lime stone required to reduce SO2 emission ??















We know that, Lime stone is nothing but Calcium carbonate (CacO3)

 

Lime stone (CaCo3) on heating gets converted into slaked lime and carbon dioxide

 

i.e,

CaCo3 + Heat = Cao + Co2

Shall calculate, quantity of CacO3 required for converting into Cao.

Molecular weight of Ca = 40 g/mol

Molecular weight of Oxygen = 16 g/mol

Molecular weight of Carbon = 12 g/mol

Molecular weight of Sulphur = 32 g/mol

Sulphur on heating gets converted into Sulphur di-oxide (SO2)

Therefore we have,

CaCo3 + Heat = Cao + CO2

(40+12+3X16) + Heat = (40+16) + (12+2X16)

100 + Heat           = 56 + 44

1 + Heat = 0.56 + 0.44-----------I

This implies, 1 kg of calcium carbonate (CaCO3) on heating gets converted into 0.56 kg of slaked lime & 0.44 kg of CO2

Further,Sulphur present in coal, on combustion gets converted into sulphur dioxide (SO2)

Shall calculate, quantity of SO2 generated on combustion of 1 kg of sulphur

 

S + O2 = SO2

32 + 2X16 = 32+2X16

32 + 32 = 64

1 + 1 = 2-----II

This means, 2 kg of SO2 will produce on combustion of 1 kg of sulphur.

Further,Slaked lime (Cao) reacts with Sulphur dioxide (SO2) & converts into Calcium sulphate (CaSO4)

i.e

Cao + SO2 + O2 = CaSO4

(40+16) + (32 + 2X16) + 16 = (40+32+4X16)

56 +(32 + 2X16) + 16 = 136

56 + 64 + 16 = 136

0.875 + 1 + 0.25 = 2.12------III

This means, 1 kg of So2 needs 0.875 kg of Cao to produce  2.42 kg of Calcium sulphate

i.e, On burning 1 kg of sulphur there produces 2 kg of SO2 (refer equation-II), hence Cao required to reduce sulphur from 1 kg So2 = 2 X 0.875 = 1.75 kg

Similarly referring equation-I, 1 kg of calcium carbonate (CaCO3) on heating gets converted into 0.56 kg of slaked lime(Cao)

Therefore  lime stone required for 1 kg sulphur to convert it into CaSO4 is;

 

1.75/0.56 = 3.125 kg

Considering 95% efficiency for above combustion, total lime stone required for 1 kg sulphur to get converted it into CaSo4 is;

3.125 X 105% = 3.28 kgs-------IV

 

Demonstration with example.

A 50 MW coal based power plant has specific fuel consumption 0.75 kg/kwh.The sulphur content in the coal is 0.75%, the maximum permissible limit of sulphur in the coal is 0.5%.Calculate the amount of lime stone required to reduce SO2 emission.

 

Assuming SO2 emission at 0.5% sulphur in coal is normal.

Extra % of sulphur in coal is = 0.75-0.5 = 0.25%

Coal consumption per day

Specific fuel consumption = 0.75 kg/kwh

Total power generation in a day = 50 X 1000 X 24 = 1200000 kw

Total coal consumption = 1200000 X 0.75 / 1000 = 900 MT/day

Extra Sulphur burned  = 900 X 0.25% = 2.25 MT or 2250 kg/day

Lime stone required to reduce SO2 emission is 2250 X 3.28 = 7380 kg (refer equation-IV)

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What is the significance of Drain cooler approach (DCA)??

 










In the context of feed water heaters, "DCA" could stand for "Drain Cooler Approach." The drain cooler approach in feed water heaters is a parameter that represents the temperature difference between the temperature of the extracted steam and the temperature of the drain (condensate) leaving the feed water heater.

 

Feed water heaters are devices used in power plants to preheat the water before it enters the boiler. The heat for this preheating process comes from extracting steam from various stages of the turbine. The drain cooler approach is a key parameter to monitor and control because it affects the overall efficiency of the power plant.

 

A lower drain cooler approach means that more heat is transferred from the extracted steam to the feed water, increasing the overall efficiency of the power plant. It's an important factor in designing and operating feed water heaters to optimize the thermal performance of the power generation system.

 

DCA is the temperature difference between the drains (steam condensate) leaving the heater and the temperature of feed water entering the heater. For more cycle efficiency TTD value should be small.

 

 Significance of DCA. 

1-It gives the feed back on performance of heat exchanger

2-Higher TTD is nothing but thee is more difference between saturation temperature of steam and feed water leaving the heater.This indicates the poor performance of heater.Similarly lower TTD is nothing but thee is small difference between saturation temperature of steam and feed water leaving the heater.This indicates the good heat transfer between steam and feed water & hence there is better performance of heater

3-The concept of "temperature approach" is closely related to ΔT. The temperature approach is the difference between the temperature of the hot fluid and the temperature of the cold fluid at the end of the heat exchanger. A smaller temperature approach is often desired to maximize heat transfer efficiency, but it is limited by practical considerations.

4-the terminal temperature difference is a key parameter in the analysis, design, and optimization of heat exchange systems. It plays a vital role in determining heat transfer rates, efficiency, and the size of heat exchangers, ultimately impacting the performance and cost of thermal systems in various engineering applications

5-Station heat rate will improve

6-Cycle efficiency will increase

7-Less steam consumption for feed water heating


Click here to know about Terminal temperature difference in feed water heaters


Calculation of DCA

1-A HP heater is used to heat the feed water from 170 °C to 190 °C by using turbine bleed steam at 17 kg/cm2 and 340 °C. The condensate returning from heater is at 180 °C, calculate the DCA of heater.

We have,

DCA = Temperature of condensate leaving the heater – Temperature of feed water entering the heater

DCA = 180 - 170 = 10 °C

Note: For best performance, heaters are designed to get DCA 3 to 5 °C at full operation capacity.

 

2-A LP heater is used to heat the feed water from 55 °C to 70 °C by using turbine extraction steam at 1.1 kg/cm2 and 125 °C. The condensate returning from heater is at 75 °C, calculate the DCA of heater.

We have,

DCA = Temperature of condensate leaving the heater – Temperature of feed water entering the heater

DCA = 75 - 55 = 20 °C

Note: For best performance, heaters are designed to get DCA 3 to 5 °C at full operation capacity.


For more>>>visit: powerplantandcalculations.com

 

What is the significance of Terminal temperature difference (TTD) in feed water heaters ???



 

 


 

 

 

 

 

 

 






The Terminal Temperature Difference (ΔT or delta T) is a crucial concept in the field of heat transfer and thermodynamics. It represents the temperature difference between the hot and cold fluids in a heat exchanger at the point where they leave the heat exchanger. The significance of terminal temperature difference lies in its impact on the efficiency and performance of heat exchange processes.

 

Terminal temperature difference is the difference between the saturation temperature at the operating pressure of the inlet steam to the heater and the temperature of the feed water leaving the heater.

The heating steam temperature they are talking about is the saturation temperature of the steam for the given supply pressure. The highest pressure heater is almost always receiving steam that is still superheated (Energy above saturation temp/pressure) If the incoming steam has 15 degrees of superheat, and the outgoing feed water absorbs all of that and is heated to 2 degrees above the saturation temperature of the supplied heating steam pressure, You have a negative 2 degree TTD.

Most of the other heaters are heated with steam from further down the turbine steam path, and have very little or no super heat in their steam, therefore, no negative TTD.

 

Click here to read more >>>>about HP heaters

Terminal temperature difference provides feedback on the feed water heater’s performance relative to heat transfer

 Significance of TTD.

 

1-It gives the feed back on performance of heat exchanger

2-Higher TTD is nothing but thee is more difference between saturation temperature of steam and feed water leaving the heater.This indicates the poor performance of heater.Similarly lower TTD is nothing but thee is small difference between saturation temperature of steam and feed water leaving the heater.This indicates the good heat transfer between steam and feed water & hence there is better performance of heater

3-The concept of "temperature approach" is closely related to ΔT. The temperature approach is the difference between the temperature of the hot fluid and the temperature of the cold fluid at the end of the heat exchanger. A smaller temperature approach is often desired to maximize heat transfer efficiency, but it is limited by practical considerations.

4-the terminal temperature difference is a key parameter in the analysis, design, and optimization of heat exchange systems. It plays a vital role in determining heat transfer rates, efficiency, and the size of heat exchangers, ultimately impacting the performance and cost of thermal systems in various engineering applications

5-Station heat rate will improve

6-Cycle efficiency will increase

7-Less steam consumption for feed water heating


Read more>>>> on Drain cooler approach-DCA


 Calculation of TTD of feed water heater.

 1-A HP heater is used to heat the feed water from 125 °C to 160 °C by using MP steam at pressure 13 kg/cm2 at temperature 280 °C, calculate the TTD.

We have,

TTD = Saturation temperature of inlet steam - Feed water outlet temperature

Saturation temperature of inlet steam at 13 kg/cm2g pressure = 195.6 °C

TTD = 195.6 - 160 = 35.6 °C

Note: For best performance, heaters are designed to get TTD 3 to 5 °C at full operation capacity.

 2-A LP heater is used to heat the feed water from 80 °C to 110 °C by using LP steam at pressure 2.5 kg/cm2A at temperature150 °C, calculate the TTD.

 We have,

TTD = Saturation temperature of inlet steam - Feed water outlet temperature

Saturation temperature of inlet steam at 2.5 kg/cm2g pressure = 125°C

 TTD = 125-110= 15 °C

 3-A HP heater is used to heat the feed water from 105°C to 140 °C by using MP steam at pressure 8 kg/cm2 at temperature 220 °C, calculate the TTD.

We have,

TTD = Saturation temperature of inlet steam - Feed water outlet temperature

Saturation temperature of inlet steam at 8 kg/cm2g pressure = 170 °C

TTD = 170 - 140 = 30 °C

 Note: For best performance, heaters are designed to get TTD 3 to 5 °C at full operation capacity.

 4-A LP heater is used to heat the feed water from 47 °C to 78 °C by using LP steam at pressure 0.62 kg/cm2A at temperature 87 °C, calculate the TTD.

 We have,

TTD = Saturation temperature of inlet steam - Feed water outlet temperature

Saturation temperature of inlet steam at 0.62 kg/cm2g pressure = 87 °C

TTD = 87 - 78 = 9 °C

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How do you calculate the quantity of condensate generated in steam lines???

 How do you calculate the quantity condensate generated in steam lines???

 












How does condensation happens in steam line?

Condensation formation in steam lines is a common issue in steam distribution systems, and it can lead to various problems, including

  • Reduced energy efficiency,
  • Equipment damage,
  • Operational issues.
  • Poor steam quality
  • Disturbances in process

How does condensation happens in steam line?

Condensation occurs when hot steam comes into contact with a surface that is cooler than its dew point temperature, causing the steam to lose heat and change phase into water droplets. Here are some factors to consider when dealing with condensation in steam lines:

Calculation:

A 100 TPH Boiler operating at of working pressure 87 kg/cm2 and 515 deg C supplies steam to 20 MW Turbine.The pressure and temperature at Turbine inlet are 85 kg/cm2 and 505 deg C, calculate the quantity of condensate formed.

 

Solution:

Enthalpy of steam at 87 kg/cm2 and 515 deg C =819 kcal/kg

Enthalpy of steam at 85 kg/cm2 and 505 deg C =814 kcal/kg

Enthalpy difference = 819-814 = 5 kcal/kg

Enthalpy of evaporation at average steam pressure 86 kg/cm2 is =332 kcal/kg

There fore,quantity of condensate generated = (100 X 5 / 332) =1.5 TPH

 

A process is situated at 500 meter from Turbine exhaust line.The exhaust pressure is 3 kg/cm2 and 150 deg C temperature and the steam paameters at process are 2.2 kg/cme and 138 deg C, quantity of steam supplied for process is 75 TPH.Calculate the condensation formed in steam line

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Solution:

Enthalpy of steam at 3 kg/cm2 and 150 deg C =657 kcal/kg

Enthalpy of steam at 2.2 kg/cm2 and 138 deg C =654 kcal/kg

Enthalpy difference = 657-654 = 3 kcal/kg

Enthalpy of evaporation at average steam pressure 2.6 kg/cm2 is =519 kcal/kg

There fore,quantity of condensate generated = (75 X 3 / 519) =0.43 TPH

 

What are the factors to be considered when dealing with steam line and condensation

 

How do you reduce steam condensation?

 

Temperature Differential: The primary cause of condensation is the temperature difference between the steam and the surrounding environment. To minimize condensation, you can either insulate the steam lines to maintain the steam's temperature or increase the temperature of the surrounding environment.

 

Insulation: Proper insulation of steam lines is crucial. High-quality insulation helps to maintain the temperature of the steam and prevents it from coming into contact with cooler surfaces. Insulation materials like fiberglass, mineral wool, or foam are commonly used for this purpose.

 

Steam Traps: Steam traps are essential components in steam systems. They are used to remove condensate from the steam lines while allowing steam to pass. Regular maintenance and inspection of steam traps can prevent condensate buildup.

 

Proper Sloping: Steam lines should be installed with a slight downward slope in the direction of condensate flow. This helps the condensate to drain away from the steam-carrying pipe, reducing the chances of condensate buildup.

 

Drainage Points: Install drainage points at low spots in the steam lines or at points where condensation is likely to occur. These drainage points should be equipped with proper traps and drains to remove condensate effectively.

 

Steam Pressure: Maintaining the proper steam pressure in the lines can also help reduce condensation. Lowering the pressure can reduce the temperature differential, which decreases the likelihood of condensation.

 

Steam Quality: Ensure that the steam quality is high. Wet or low-quality steam is more likely to condense. Proper steam generation and water treatment are essential to achieve high-quality steam.

 

Air Venting: Properly vent steam lines to remove air, which can contribute to temperature variations and condensation issues.

 

Monitoring and Maintenance: Regularly monitor steam lines for signs of condensation, such as water droplets or corrosion. Perform routine maintenance to address any issues promptly.

 

Heat Tracing: In some cases, heat tracing systems can be used to maintain the temperature of the steam lines, preventing condensation.

 

Pipe Material: The choice of pipe material can also impact condensation. Some materials, like copper, conduct heat more effectively and may be less prone to condensation compared to others.

 

Addressing condensation in steam lines is essential for the efficient and safe operation of steam systems. It helps prevent damage to equipment, ensures consistent steam quality, and reduces energy losses. Proper design, insulation, and maintenance are key to minimizing condensation-related issues in steam lines.


For more>>>>>Read Power plant and calculations

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