NO X EMISSIONS FROM HEAVY FUEL OIL BOILERS M. LAKS*, D. STEFANOVSKI, J. DIMZOVA Environmental Laboratory, FARMAHEM, Kicevska 1, 1060 Skopje, Macedonia E-mail: ekolab@farmahem.com.mk
Scope of investigation Farmahem Environmental Laboratory is an accredited testing laboratory according to ISO 17025:5 by IARM in the field of air, noise and water. For the emission measurement in air, Farmahem has 7 accredited measuring parameters which include nitrogen oxides, oxygen and temperature. The 66 measurements of emissions from boilers that use fuel oil (light and heavy fuel oil) were performed in the period of 9 2015. The thermal power of the tested boilers was in the range from 0,2 MW up to 50 MW. The boilers did not have an installed system for reduction of nitrogen oxides (pre or post system of reduction of NO x ). The emission limit value for nitrogen oxides NO x from boilers that use fuel oil is mg/m 3, according to the Rulebook for limit values for emission levels and types of pollutants in waste gases and vapors emitted by stationary sources into the air, Official Gazette of R. Macedonia No. 141/2010).
Equipment and methods The measurements of nitrogen oxides, oxygen and temperature have been performed with Testo XL/454. The concentrations of oxygen, nitrogen monoxide and nitrogen dioxide have been determined by the electrochemical cell. The temperature was determined by a thermocouple. The measurements have been performed in the period from several minutes up to 2 hours. The test of homegenity has been performed before testing for oxygen according to MKC EN 15259:9. The Quality assurance (QA) and Quality control (QC) were carried out with internal calibration using certified reference gases and leakage test. The measurement sites for emission of gases and flow satisfied the criteria specified in method МКС ISO 10780:8 and MKC EN 15259:9.
Results from emission of NO x from boilers that use light fuel oil and limit value of NO x mg/m3 3%O2 380 360 340 320 280 260 240 220 180 160 140 120 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Boiler No. Limit value measured value
Real measurement of emission for boiler that use light fuel oil and have values for NO x close to the limit value Emission of NOX by boiler that use light fuel oil mg/m 3 3%O2 150 10:37 10:38 10:39 10:40 10:41 11:12 11:13 11:14 11:15 11:16 11:29 11:30 11:31 11:32 11:33 11:38 11:39 11:40 11:41 11:42 Average concentration of NO x and expanded uncertainty (k=2) Emission of NOX from boiler that use light fuel oil measured value of ELV mg/m 3 3%O2 360 340 320 280 260 240 220 0 1 boiler Average value of NOX ELV
Results from emission of NO x from boilers that use heavy fuel oil and limit value of NO x 900 850 750 mg/m 3 3%O2 650 550 450 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Boiler No. Limit value measured value
Real measurement for boiler that use heavy fuel oil and have values for NO x close to the emission limit value Sample of measurement of emission of from boiler that use heavy fuel oil mg/m 3 3%O2 450 150 09:10 09:20 09:30 Measured value of NOX ELV Average concentration of NO x and expanded uncertainty (k=2) Emission of from boiler that use heavy fuel oil 450 mg/m 3 3%O2 2 boiler that use heavy fuel oil ELV 0 2 boiler
Nitrogen oxides emission factors Nitrogen content in fuel Temperature (flame temperature and combustion air temperature) Excess air
Impact of temperature on nitrogen oxides emission Comparisation of emission of Nox and temperature (mg/m 3 3%O 2 ) FT ( o C) 0 900 0 13:04:32 13:05:02 13:05:32 13:06:02 13:06:32 13:07:02 13:07:32 13:08:02 13:08:32 13:09:02 13:09:32 13:10:02 13:10:32 13:11:02 13:11:32 13:12:02 13:12:32 13:18:19 13:18:49 13:19:19 14:05:45 14:08:18 14:08:48 14:09:18 14:09:48 14:10:18 FT (mg/m 3 3%O2) 750 650 550 11:27 11:28 11:29 11:30 11:41 11:42 Comparisation of emission of Nox and temperature 11:43 11:48 11:49 11:54 11:55 12:22 12:23 12:24 12:25 12:34 12:35 12:36 12:37 12:38 12:50 12:51 12:52 260 240 220 180 160 140 120 FT (oc) FT 0 900 08:59:28 09:00:18 09:01:08 09:01:58 09:02:48 09:03:38 09:04:28 09:05:18 09:06:08 09:06:58 09:07:48 09:08:38 09:44:29 09:45:19 09:46:09 09:46:59 09:47:49 09:54:43 09:55:33 09:56:23 FT 09:57:13 09:58:03 09:58:53 09:59:43 10:00:33 10:01:23 10:02:13 10:03:03 10:03:53 150 FT FT ( o C) (mg/m3) 280 260 240 220 180 160 140 FT 120 10:37:04 10:38:04 10:39:04 10:40:04 10:41:04 11:12:43 11:13:43 11:14:43 11:15:43 11:16:43 11:29:55 11:30:55 11:31:55 11:32:55 11:33:55 11:38:44 11:39:44 11:40:44 11:41:44 11:42:44
Impact of excess of air on nitrogen oxides emission Comparisation of emission of and excess air (mg/m 3 3%O2) ( o C) 750 650 550 450 11:27 11:28 11:29 11:30 11:41 11:42 11:43 11:48 11:49 11:54 11:55 12:22 12:23 12:24 12:25 12:34 12:35 12:36 12:37 12:38 12:50 12:51 12:52 1,40 1,30 1,20 1,10 1,00 λ lambda (mg/m 3 3%O2) 275 225 175 150 125 2,00 1,90 1,80 1,70 1,60 1,50 1,40 1,30 1,20 1,10 1,00 λ 0 900 1,30 1,25 1,20 1,15 1,10 1,05 1,00 excess of air 10:37 10:38 10:39 10:40 10:41 11:12 11:13 11:14 11:15 11:16 11:30 11:31 11:32 11:33 11:38 11:39 11:40 11:41 11:42 11:29 08:59:28 09:00:18 09:01:08 09:01:58 09:02:48 09:03:38 09:04:28 09:05:18 09:06:08 09:06:58 09:07:48 09:08:38 09:44:29 09:45:19 09:46:09 09:46:59 09:47:49 09:54:43 09:55:33 09:56:23 09:57:13 09:58:03 09:58:53 09:59:43 10:00:33 10:01:23 10:02:13 10:03:03 10:03:53 λ λ
Conclusions Emission limit value Light fuel oil: the measured values for concentration of NO x satisfied the emission limit value for all boilers that use light fuel oil. Heavy fuel oil: the measured values for concentration of NO x exceeded the emission limit value for all boilers that use heavy fuel oil. Impact of temperature and excess of air: NO x emission is proportional with temperature of flue gases, but it s not crucial factor for achieving of emission limit values of NO x. Future trend: All boilers that operate with heavy fuel oil have to install a system for reduction of nitrogen oxides. Thank you for your attention!