How to calculate power plant emissions – solution to problem of a reader
How to calculate power plant emissions – solution to problem of reader
Hi,
Please find on the next page a snippet of my spreadsheet showing the solution. The model was calibrated to the above municipal solid fuel analysis at 80% excess air firing for combustion of municipal solid waste to meet the given SO2 emission of 15.75 mg/Nm3.
Assuming 26% thermal efficiency and given firing rate of 185,000 metric tons per year of 7018 hours (around 80% capacity factor), your plant must be generating over 52.41 MW of power with 9% plant own use (parasitic load assumed).
The fuel should have a sulfur analysis of 0.57% Sulfur (dry basis) in order to give such emission.
At 31.30% moisture in the wet fuel, this translates to 0.39% Sulfur (wet basis).
Once the sulfur in the wet fuel is known, the problem is solved:
kg SO2 per metric ton fuel (wet) = (0.39 / 100) x (mw of SO2 / mw of S) x (1000 kg / metric ton)
= (0.39 / 100) x (64.0648 / 32.0660) x (1000) = 7.806 kg SO2 per metric ton (tonne) of wet fuel
My excel model basically has all the formulas in it, so using goal seek to meet a particular gas analysis (15.75 mg SO2/Nm3) will provide the sulfur (S) content of the fuel and therefor its equivalent sulfur dioxide (SO2) content from the ratio of molecular weights.
If you are interested in my calculation sheet, kindly use the DONATE button and remit the requested amount of $100 representing my daily rate for a half day’s consultancy. My website with the said DONATE button via PAYPAL is shown below:
http://www.energytechnologyexpert.com
Regards,
Marcial T. Ocampo
B.S. Chemical Engineering (University of the Philippines)
M.S. Chemical Engineering (University of the Philippines)
M.S. Combustion & Energy (University of Leeds, UK)
Energy Technology & Pricing Expert
Business Development Consultant
Project Finance and Financial Modeling
email mars_ocampo@yahoo.com
web www.energytechnologyexpert.com
P.S. Please see next page for a portion of the spreadsheet.
| Great blog! | ||||||||||||||
| I need help converting waste incineration emissions from mg/Nm3 to kg/tonne waste. | ||||||||||||||
| for example if the total waste in a year incinerated is 185000 tonnes and SO2 is | ||||||||||||||
| emitted at 15.75mg/Nm3 and the plant is in operation for 7018 hours a year what is SO2 in kg/t? | ||||||||||||||
| Thanks in advance and keep up the good work! | ||||||||||||||
| Given Data: | ||||||||||||||
| 185,000 | metric tons (tonnes) of municipal waste | |||||||||||||
| 15.75 | mg/Nm3 of SO2 | |||||||||||||
| 7,018 | hours per year operation | |||||||||||||
| Problem: | Determine kg SO2 per tonne of waste | |||||||||||||
| Assumptions: | ||||||||||||||
| 1) Assumed Fuel | Municipal Solid Waste | from Fuels sheet | ||||||||||||
| 11,836 | Gross Heating Value, Btu/lb | from Fuels sheet | ||||||||||||
| 11,340 | Net Heating Value, Btu/lb | from Fuels sheet | ||||||||||||
| 2) Ultimate Analysis, % weight (dry basis) | ||||||||||||||
| 40.61 | %C | from Fuels sheet | ||||||||||||
| 5.39 | %H | from Fuels sheet | ||||||||||||
| 0.57 | %S | Vary cell Y53 to zero by varying cel A28 (press ctrl + d) | ||||||||||||
| 30.13 | %O | from Fuels sheet | ||||||||||||
| 0.29 | %N | from Fuels sheet | ||||||||||||
| 23.01 | %ASH | Adjust ash so that total is 100% (by difference) | ||||||||||||
| 100.00 | Total Dry Fuel | |||||||||||||
| 31.30 | %H20 | from Fuels sheet | ||||||||||||
| 3) Ultimate Analysis, % weight (wet basis) | ||||||||||||||
| 27.90 | %C | calculated | ||||||||||||
| 3.70 | %H | calculated | MW S | MW SO2 | ||||||||||
| 0.39 | %S | calculated | 32.0660 | 64.0648 | 0.781 | kg SO2 per 100 kg fuel | ||||||||
| 20.70 | %O | calculated | 7.806 | kg SO2 per metric ton fuel | ||||||||||
| 0.20 | %N | calculated | ||||||||||||
| 15.81 | %ASH | calculated | ||||||||||||
| 31.30 | %H20 | calculated | ||||||||||||
| 100.00 | Total Wet Fuel | |||||||||||||
| Solution: | Municipal Solid Waste firing (80-100% excess air) – assume 80% excess air firing | |||||||||||||
| Press ctrl + d to converge model to 15.75 mg/Nm3 SO2 in the flue gas | ||||||||||||||
| 0.781 | lb SO2 per 100 lb of fuel = kg SO2 per 100 kg fuel | |||||||||||||
| 7.806 | kg SO2 per metric ton fuel | ANSWER TO YOUR PROBLEM | ||||||||||||
| 9.422% | % excess Oxygen in flue gas (dry gas) at 80% excess air firing | |||||||||||||
| As Measured | 6% | Reference | ||||||||||||
| Flue Gas | lb mole/ | % vol | % vol | ppm V | mg / Nm3 | ppm V | mg / Nm3 | |||||||
| lb/100 lb | 100 lb | (WET) | (DRY) | (DRY) | (DRY) | (DRY) | (DRY) | |||||||
| CO2 | 102.229 | 2.323 | 9.039% | 10.499% | Actual | |||||||||
| H2O | 33.066 | 1.835 | 7.142% | mg/Nm3 | ||||||||||
| SO2 (COMPUTED) | 0.781 | 0.012 | 0.047% | 0.055% | 5.51 | 15.75 | 7.13 | 20.41 | 15.75 | |||||
| NO2 (MEASURED) | 0.000 | 0.000% | 0.000% | 10.00 | 20.54 | 12.96 | 26.61 | Variance | ||||||
| CO (MEASURED) | 5.00 | 6.25 | 6.48 | 8.10 | 0.00 | |||||||||
| O2 | 66.708 | 2.085 | 8.112% | 9.422% | ||||||||||
| N2 (fuel) | 0.200 | 0.007 | 0.028% | 0.032% | ||||||||||
| H2O | 31.300 | 1.737 | 6.761% | |||||||||||
| N2 (air) | 498.415 | 17.699 | 68.871% | 79.992% | ||||||||||
| wet gas | 732.698 | 25.698 | 100.000% | 100.000% | ||||||||||
| dry gas | 1.800 | 22.126 | ||||||||||||
| From % wt | Table 2 – Calculation of Combustion Products and Theoretical Oxygen Requirements – Molar Basis (Babcock & Wilcox, p. 9-4) | |||||||||||||
| Molecular | Analysis | Moles per | Analysis | Gross HV | Net HV | Combustion | Molecular | Oxygen | Theoritical Air, lb/100 lb fuel | |||||
| No. | Substance | Formula | Weight | % wt | 100 lb fuel | % vol | btu/lb | btu/lb | Products | Weight | Required | O2 (moles) | N2a | Air |
| 1 | Carbon | C | 12.0110 | 27.90 | 2.3229 | 35.40 | 14093 | 14093 | CO2 | 44.0098 | 1.00 | 2.3229 | ||
| 2 | Hydrogen | H2 | 2.0159 | 3.70 | 1.8354 | 27.97 | 61095 | 51625 | H2O | 18.0153 | 0.50 | 0.9177 | ||
| 29 | Sulfur | S | 32.0660 | 0.39 | 0.0122 | 0.19 | 3980 | 3980 | SO2 | 64.0648 | 1.00 | 0.0122 | ||
| NOX | NO2 | 46.0055 | 0.00 | 0.0000 | 0.00 | NO2 | 46.0055 | 1.00 | 0.0000 | |||||
| CO | CO | 28.0104 | 0.00 | 0.0000 | 0.00 | 4347 | 4347 | CO | 28.0104 | -0.50 | 0.0000 | |||
| 3 | Oxygen | O2 | 31.9988 | 20.70 | 0.6469 | 9.86 | O2 | 31.9988 | -1.00 | -0.6469 | ||||
| 4 | Nitrogen | N2 | 28.0134 | 0.20 | 0.0071 | 0.11 | N2 (fuel) | 28.0134 | 0.00 | |||||
| 32 | Water Vapor | H20 | 18.0153 | 31.30 | 1.7374 | 26.48 | H2O | 18.0153 | 0.00 | |||||
| Ash | 15.81 | N2 (air) | 28.1610 | 2.6059 | ||||||||||
| TOTAL | 15.2394 | 100.00 | 6.5619 | 100.00 | 6208 | 5858 | 83.3847 | 276.8972 | 360.2819 | |||||
| GIVEN | 5858 | 23.14% | 76.86% | 100.00% | ||||||||||
| 31.9988 | 28.1610 | 28.9660 | ||||||||||||
| per lb fuel | 0.834 | 2.769 | 3.603 | |||||||||||
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November 25th, 2009 at 8:05 am
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