How to calculate power plant emissions - solution to problem of a reader

How to calculate power plant emissions – solution to problem of a reader

October 30th, 2009 Posted in environmental impacts, power plant emissions

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

energydataexpert@gmail.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

Tags: environmental impacts, pollution emissions, power generation, power generation technologies, power generation technology, power plant, power plant design, power plant emissions

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