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  • g/kWh to mg/nm3 for diesel generator

    Dear All,

    can any body help me to convert the following,

    there is a diesel engine of 440 kwe (550 KVA), its NOx emissions are 444 g/kWh.
    Please convert it in mg/nm3.

    your prompt cooperation in this regard would be much appreciated.

    waiting....

  • #2
    Re: g/kWh to mg/nm3 for diesel generator

    Originally posted by warifir View Post
    Dear All,

    can any body help me to convert the following,

    there is a diesel engine of 440 kwe (550 KVA), its NOx emissions are 444 g/kWh.
    Please convert it in mg/nm3.

    your prompt cooperation in this regard would be much appreciated.

    waiting....
    That figure seems incredibly high. Are you sure that isn't the fuel consumption? If it is NOx, it is perhaps the worst engine ever built.

    Anyway 440 kW x 444 g/kWh = 195360 g/h = 195.360 kg/h. You would have to determine the total exhaust volume during the hour to calculate concentration.

    Comment


    • #3
      Re: g/kWh to mg/nm3 for diesel generator

      Originally posted by JohnS View Post
      That figure seems incredibly high. Are you sure that isn't the fuel consumption? If it is NOx, it is perhaps the worst engine ever built.

      Anyway 440 kW x 444 g/kWh = 195360 g/h = 195.360 kg/h. You would have to determine the total exhaust volume during the hour to calculate concentration.
      Dear JohnS,

      thank u so much for your reply. basically the diesel engine is from Germany. and the value of NOx was written like this way "4,44 g/kWh" and i couldn't understand whether the value is "444 or 4.44" that's why i had the big value. Anyways thank u so much for your reply. i will get the exhaust volume and then check the final value in mg/nm3. ok tc cya...thanks once again.

      Comment


      • #4
        Re: g/kWh to mg/nm3 for diesel generator

        Originally posted by warifir View Post
        Dear JohnS,

        thank u so much for your reply. basically the diesel engine is from Germany. and the value of NOx was written like this way "4,44 g/kWh" and i couldn't understand whether the value is "444 or 4.44" that's why i had the big value. Anyways thank u so much for your reply. i will get the exhaust volume and then check the final value in mg/nm3. ok tc cya...thanks once again.
        It is a decimal comma. Many European countries (other than English speaking ones) use a comma as the decimal marker. It is 4.44, so divide by 100.

        The figure is still VERY high. Heavy truck engines manufactured in 2007 and after are spec'd at 0.2 g/bhph, about 0.27 g/kWh, about 16-fold better. I don't know what standards apply to staionary engines.
        Last edited by JohnS; 01-16-2012, 09:32 AM.

        Comment


        • #5
          Re: g/kWh to mg/nm3 for diesel generator

          Originally posted by JohnS View Post
          It is a decimal comma. Many European countries (other than English speaking ones) use a comma as the decimal marker. It is 4.44, so divide by 100.

          The figure is still VERY high. Heavy truck engines manufactured in 2007 and after are spec'd at 0.2 g/bhph, about 0.27 g/kWh, about 16-fold better. I don't know what standards apply to staionary engines.
          Dear JohnS,

          Please assist that below calculations are correct or not? because Nox values looks under the limit,


          Nox = 4.44 g/kWh

          Power = 440 kWe

          Required: NOx value in mg/nm3

          therefore,

          440 kWe x 4.44 g/kWh = 1,953.6 g/hr

          Now, the total exhaust gas volume in one hour is = 4,980 m3/hr

          1,953.6 g/hr
          ------------
          4,980 m3/hr


          Ans: 0.392 g/m3

          and so we get, 392 mg/m3

          JohnS, if my answer is right then the NOx value is under control without any catalytic converter. please reply me ASAP i will be very thankful to you.

          if answer is not correct and i did a mistake then plz assist.
          Last edited by warifir; 01-17-2012, 12:15 AM.

          Comment


          • #6
            Re: g/kWh to mg/nm3 for diesel generator

            Originally posted by warifir View Post
            Dear JohnS,

            Please assist that below calculations are correct or not? because Nox values looks under the limit,


            Nox = 4.44 g/kWh

            Power = 440 kWe

            Required: NOx value in mg/nm3

            therefore,

            440 kWe x 4.44 g/kWh = 1,953.6 g/hr

            Now, the total exhaust gas volume in one hour is = 4,980 m3/hr

            1,953.6 g/hr
            ------------
            4,980 m3/hr


            Ans: 0.392 g/m3

            and so we get, 392 mg/m3

            JohnS, if my answer is right then the NOx value is under control without any catalytic converter. please reply me ASAP i will be very thankful to you.

            if answer is not correct and i did a mistake then plz assist.
            The calculation looks correct. I don't know what your limit is for a stationary engine.

            Comment


            • #7
              Re: g/kWh to mg/nm3 for diesel generator

              Originally posted by JohnS View Post
              The calculation looks correct. I don't know what your limit is for a stationary engine.
              Dear JohnS,

              can you tell me the limits of diesel NOx in USA, in mg/nm3?

              and please let me know whether natural gas produces higher NOx or Diesel fuel?

              your kind cooperation in this regard will be highly appreciated.

              Comment


              • #8
                Re: g/kWh to mg/nm3 for diesel generator

                Originally posted by warifir View Post
                Dear JohnS,

                can you tell me the limits of diesel NOx in USA, in mg/nm3?

                and please let me know whether natural gas produces higher NOx or Diesel fuel?

                your kind cooperation in this regard will be highly appreciated.
                The US does not specify it that way. For passenger car and light truck, the limits are in grams per mile. For heavy truck (and coach), off-road equipment, marine, and stationary engines, the limits are grams per brake horsepower hour, regardless of how the shaft power is used. The regulations do not consider the volume of exhaust. Each category above has its own limits by year of manufacture, with stationary engine the least regulated. (the above "mixed" units are easily converted to SI; divide approximately by 1.61 km/mi or 0.746 kW/bhp)

                Natural gas is normally burned at stoichiometry (or very nearly) and has low NOx. It naturally produces lower CO and HC than gasoline and is easily cleaned up with after-treatment. Diesel is normally burned lean (excess air) to control CO, HC, PM, but this tends to produce high NOx. With tighter NOx regulation, after-treatment is required in heavy truck and coach. The other limits are lax enough that after-treatment may be avoided. Probably in the future, all of the limits in various categories will converge towards those for heavy truck engines.

                There are so many categories and years (and power level) with different limits you will have to Google to find what you want. The EPA has pretty good lists.

                Comment


                • #9
                  Re: g/kWh to mg/nm3 for diesel generator

                  Originally posted by JohnS View Post
                  The US does not specify it that way. For passenger car and light truck, the limits are in grams per mile. For heavy truck (and coach), off-road equipment, marine, and stationary engines, the limits are grams per brake horsepower hour, regardless of how the shaft power is used. The regulations do not consider the volume of exhaust. Each category above has its own limits by year of manufacture, with stationary engine the least regulated. (the above "mixed" units are easily converted to SI; divide approximately by 1.61 km/mi or 0.746 kW/bhp)

                  Natural gas is normally burned at stoichiometry (or very nearly) and has low NOx. It naturally produces lower CO and HC than gasoline and is easily cleaned up with after-treatment. Diesel is normally burned lean (excess air) to control CO, HC, PM, but this tends to produce high NOx. With tighter NOx regulation, after-treatment is required in heavy truck and coach. The other limits are lax enough that after-treatment may be avoided. Probably in the future, all of the limits in various categories will converge towards those for heavy truck engines.

                  There are so many categories and years (and power level) with different limits you will have to Google to find what you want. The EPA has pretty good lists.
                  Dear JohnS,
                  Thank u so much for ur prompt replies. U know y i m confuesd for diesel cuz we r the dstrbutor of both gas n diesel generators. For gas generators,we have nox values in mg/nm3 and these are around 1200 mg/nm3. But for diesel we have the values in g/kwh n when i convert it according to the method which u have checked then it gives around 400 mg/nm3. That's y i m much confued that how a diesel engine can give lowest values of nox than gas engine, even without catalytic convertr. Even the size of both engines r same n both are power generation units. That's y i m keep asking. Sorry for any inconvenience this may have caused.
                  Last edited by warifir; 01-17-2012, 07:21 AM.

                  Comment


                  • #10
                    Re: g/kWh to mg/nm3 for diesel generator

                    Are the gas engines operated lean or at stoichiometry? Lean raises NOx substantially and generally requires active NOx aftertreatment (as it does in diesel, the problem is the excess O2)

                    Here is an example of a commercial natural gas engine (rated for heavy vehicle use) that meets 0.2 g/bhph NOx (about 0.27 g/kWh). It uses a conventional three-way catalyst.
                    http://www.cumminswestport.com/products/islg.php

                    Edit: May I suggest checking the exhaust flow calculation. That seems very high. At 25:1 air/fuel, which is pretty lean, it would suggest around 280 L of diesel per hour. I'm not sure how you derived it, but I think something is off.
                    (I assumed air mass 1.2 kg/m, 25:1 mass air fuel ratio, and diesel density 0.85 kg/L) If you overstate the exhaust volume, the NOx concentration is understated.
                    Last edited by JohnS; 01-17-2012, 08:58 AM.

                    Comment


                    • #11
                      Re: g/kWh to mg/nm3 for diesel generator

                      Dear JohnS,

                      the gas generator which i was talking about was lean engine.

                      anyways,

                      here are the spec of the diesel generator.

                      Power = 440 KWe

                      Rpm = 1500

                      Cylinder = 10-V

                      Displacement = 17.5 Liters

                      Compression Ratio = 17.5:1

                      Aspiration = 29 m3/min

                      Air Density = 1.184 kg/m3

                      Exhaust Gas Temp at stack = 540 C

                      Exhaust Gas Volume at stack = 83 m3/min

                      Max. Allowable Back Pressure = 15 Kpa

                      Please take a look of the given data and if you think that there is any discrepancy plz let me know. i know my continuous questions r keep engaging you but your cooperation is admirable. i just wanna know where is the error OR this engine will give almost 400 mg/nm3 . [if it happens and diesel generator will give NOx under mentioned limit without catalytic u dont know that will be great.]
                      Please assist.
                      Last edited by warifir; 01-17-2012, 10:51 PM.

                      Comment


                      • #12
                        Re: g/kWh to mg/nm3 for diesel generator

                        Originally posted by warifir View Post
                        Dear JohnS,

                        the gas generator which i was talking about was lean engine.

                        anyways,

                        here are the spec of the diesel generator.

                        Power = 440 KWe

                        Rpm = 1500

                        Cylinder = 10-V

                        Displacement = 17.5 Liters

                        Compression Ratio = 17.5:1

                        Aspiration = 29 m3/min

                        Air Density = 1.184 kg/m3

                        Exhaust Gas Temp at stack = 540 C

                        Exhaust Gas Volume at stack = 83 m3/min

                        Max. Allowable Back Pressure = 15 Kpa

                        Please take a look of the given data and if you think that there is any discrepancy plz let me know. i know my continuous questions r keep engaging you but your cooperation is admirable. i just wanna know where is the error OR this engine will give almost 400 mg/nm3 . [if it happens and diesel generator will give NOx under mentioned limit without catalytic u dont know that will be great.]
                        Please assist.
                        Is the engine either super-charged or a two-cycle engine? I don't understand how aspiration can be that high. At 1500 rpm, a four cycle engine could aspirate (max) 750 times its displacement per minute (2cycle, 1500). Since some pressure drop will occur in air cleaner, intake manifold, etc, aspiration should be somewhat lower.

                        The exhaust volume is obviously at exhaust temperature, otherwise it would not be that much higher than intake. As the US does not specify emissions in grams per cubic meter, I don't know the conventions, but I would think they use the volume of the exhaust at ambient conditions. For national air quality (not exhaust) the US uses milligrams per cubic meter for certain pollutants and conditions are that the data is corrected to 1 atm, 25 C.

                        You will need to check the regulations you must comply with, but I believe the exhaust volume is over-stated about 2:1 as a result of being specified at exhaust temperature, and the air intake seems high for rpm and displacement.

                        Also, in the US, the emissions limit would not consider the efficiency of the generator itself and use electricl power output, it would be based on shaft output of the engine. However, I don't know what country this is in, or the specific emission laws which apply.

                        Finally, and this points out the problem with a g/m specification, just blow fresh air into the exhaust stream and dilute it until you meet spec.

                        Comment


                        • #13
                          Re: g/kWh to mg/nm3 for diesel generator

                          Originally posted by JohnS View Post
                          Is the engine either super-charged or a two-cycle engine? I don't understand how aspiration can be that high. At 1500 rpm, a four cycle engine could aspirate (max) 750 times its displacement per minute (2cycle, 1500). Since some pressure drop will occur in air cleaner, intake manifold, etc, aspiration should be somewhat lower.

                          The exhaust volume is obviously at exhaust temperature, otherwise it would not be that much higher than intake. As the US does not specify emissions in grams per cubic meter, I don't know the conventions, but I would think they use the volume of the exhaust at ambient conditions. For national air quality (not exhaust) the US uses milligrams per cubic meter for certain pollutants and conditions are that the data is corrected to 1 atm, 25 C.

                          You will need to check the regulations you must comply with, but I believe the exhaust volume is over-stated about 2:1 as a result of being specified at exhaust temperature, and the air intake seems high for rpm and displacement.

                          Also, in the US, the emissions limit would not consider the efficiency of the generator itself and use electricl power output, it would be based on shaft output of the engine. However, I don't know what country this is in, or the specific emission laws which apply.

                          Finally, and this points out the problem with a g/m specification, just blow fresh air into the exhaust stream and dilute it until you meet spec.
                          Dear JohnS,

                          Engine is obviously 4-cycle at 1500 rpm.
                          i can not say that the specs are not correct because i gave you the whole data from the product literature of the engine therefore it can not be wrong, engine origin is GERMANY.

                          at last what can i say except that your cooperation was great and so much admirable... i m still trapped in this problem.. and no way out

                          Comment


                          • #14
                            Re: g/kWh to mg/nm3 for diesel generator

                            Originally posted by warifir View Post
                            Dear JohnS,

                            Engine is obviously 4-cycle at 1500 rpm.
                            i can not say that the specs are not correct because i gave you the whole data from the product literature of the engine therefore it can not be wrong, engine origin is GERMANY.

                            at last what can i say except that your cooperation was great and so much admirable... i m still trapped in this problem.. and no way out
                            I would urge you to consult with the engine manufacturer. The specs may not be "wrong" but may be stated at some other operating condition, for example at max flow. Since you risk compliance issues, you must be sure that the specs you are relying on are stated in accord with the compliance measurement protocol.

                            If the engine is naturally aspirated, I do not see how it can aspirate more than 13 m/min at 1500 rpm. The exhaust at ambient conditions would be about 13-14 m/min, but higher at exhaust temperature. You need to know the exhaust conditions the regulation assumes.

                            Comment


                            • #15
                              Re: g/kWh to mg/nm3 for diesel generator

                              Originally posted by JohnS View Post
                              I would urge you to consult with the engine manufacturer. The specs may not be "wrong" but may be stated at some other operating condition, for example at max flow. Since you risk compliance issues, you must be sure that the specs you are relying on are stated in accord with the compliance measurement protocol.

                              If the engine is naturally aspirated, I do not see how it can aspirate more than 13 m/min at 1500 rpm. The exhaust at ambient conditions would be about 13-14 m/min, but higher at exhaust temperature. You need to know the exhaust conditions the regulation assumes.
                              Dear JohnS,

                              well, yes i think i will have to consult with the manufacturer. No, engine is not naturally aspirated, it is turbocharged and intercooled. And as per your suggestions i m going to prepare a report so that i can find or assume the conclusion little bit.
                              thank you so much john, if i find something, i will get back to u. take care, cya

                              Comment

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