Low-nox Boiler Information For Lattner H.e. Miniature 3

Transcript

LATTNER BOILER COMPANY Low-NOx Boilers Lattner WLF Model 9.5 HP to 50 HP Lattner HE Model 3 HP to 9.5 HP ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ SCAQMD-Approved for California & Texas Less than 30 ppm NOx (corrected 3% O2) Lattner burner (see figure 3) Pre-mix combustion gas technology Improved efficiency Tubeless; Very low maintenance Small footprint Large hand holes for easy inspection and cleanout ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ SCAQMD-Approved for California & Texas Less than 30 ppm NOx (corrected 3% O2) Webster power burner (see figure 4) Flue gas re-circulation technology Four pass gas travel Improved efficiency Tubeless; Very low maintenance Removable panels for pressure vessel access Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Basic Instructions for Start-Up of Lattner Low-NOx Boilers The burner system of the Lattner low-NOx boiler consists of a gas valve with built-in pressure regulator, motor driven blower, pre-mix burner tubes and electronic ignition and flame monitoring. The system is basically similar to any boiler with a forced draft power burner and must be started in a similar fashion to any boiler with this type burner. In order to properly start the burner you will need the following items: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Combustion analyzer Stop watch Calculator Knowledge of the BTU content of the fuel gas. Method of measuring the fuel gas input in cubic feet per hour. Formula for calculating BTU input to the burner Formula for calculating NOx corrected to 3%. The maximum is 30 ppm. CO2 / O2 / Excess Air ratio curve chart Carbon monoxide tester “U” tube manometer or aneroid gas pressure gauge Before attempting to actually start the boiler, check the function of the low water cutoffs and pressure controls. The gas piping must be properly purged up to the point of connection to the gas train. It is necessary to make sure the voltage to the boiler is correct. The boiler should then be started with the fuel gas shut off to make sure no valves will open during the burner pre-purge cycle. After this check is confirmed, the gas valve to the burner train can be opened and the burner started. It is absolutely necessary to determine the firing rate of the boiler by actually determining the volume of fuel gas supplied to the boiler. Using a stop-watch and reading the fuel gas volume in cubic feet for a specific period of time at the gas meter, the actual volume of gas in cubic feet per hour is calculated using the formula for calculating the BTU input to the burner. Further calculation using the actual BTU per cubic foot of gas, the exact firing rate can be determined. (Contact the gas utility supplier to determine the BTU per cubic foot content of the fuel gas). Adjust the fuel gas pressure regulator on the combination gas valve until the BTU input matches the BTU input rating of the boiler. As the fuel gas input is changed, readjustment of the air shutter will be required to prevent the loss of burner flame. Use the combustion analyzer probe to sample the flue gas below any draft regulator (if used). In general, the 02 reading obtained on the combustion analyzer may be around 4% or slightly higher. Adjust the air shutter on the burner blower to change the readings. As air shutter adjustments are Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers made, the fuel gas pressure regulator will require minor adjustments to maintain the correct fuel gas BTU input to the burner. Any pressure regulator readjustment may also require minor changes in the air shutter adjustment. Adjust the air shutter while observing the NOx readings on the analyzer. Adjust the air shutter to obtain low NOx readings. The finalized burner adjustments are those that will produce the lowest corrected NOx readings using the formula for calculating NOx corrected to 3% calculation. Boiler is SCAQMD certified for 30 ppm NOx. Check the flue gas content for carbon monoxide. The reading must be below 400 parts per million but preferably around 40 parts per million. The “U” tube manometer or aneroid gas pressure gauge is used only to observe any changes in the manifold gas pressure as adjustments are being made. After any adjustments are finalized, record these readings for future use. These readings will probably be about 2 Inches water column pressure. Formula for calculating NOx corrected to 3% 02: Corrected value = 17.95 20.95 - 02% x ppm NOx Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Gas Input Determination by Gas Meter Measurement The gas input to a burner should be determined by “clocking” the gas meter. Failure to apply meter correction factors can lead to over firing which could result in boiler damage or an unsafe operating condition. When determining gas flows using a gas meter, several factors must be considered to obtain an accurate measurement. The inlet gas pressure and temperature to the meter must be determined and the inlet gas pressure and temperature that was used to calibrate the gas meter must be known. The calibration pressure (commonly referred to as base pressure) and temperature may be marked on the meter dial or nameplate. If this information is not on the meter then use 4 oz (7 iwc) as base pressure and 60°F as the calibration pressure and temperature. The formula for calculating the gas flow is as follows: CFH = Cu. Ft. x 3600 x Press. Corr. x Temp. Corr. Time CFH – Cubic feet per hour Cu. Ft. – Cubic feet of gas clocked 3600 – number of seconds in one hour Press. Corr. – Correction factor for inlet gas pressure different than base pressure (see figure 1) Temp. Corr. – Correction factor for inlet gas temperature different than calibration temperature (see figure 1) Time – Time in seconds required to measure Cu. Ft. Example: For example, assume the meter is calibrated with a base pressure of 4 oz and temperature of 60°F and you measure the inlet pressure to the meter as 5 psi with a gas temperature of 70°F. You determine it takes 42 seconds for 50 cu. ft. of gas to flow through the meter. For 5 psi, the pressure correction factor is 1.324 and for the 70°F the temperature correction factor is .981. The calculation is: CFH = 50 x 3600 x 1.324 x .981 42 CFH = 5566 cubic feet per hour gas flow Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers For heat input to the boiler, the CFH gas flow must be multiplied by the BTU content of the gas. Typically, the BTU content for natural gas is 1000 BTUs per cubic foot of gas and this number can be used if the actual number is not known. In the above example, if the BTU content of the gas is 1050 BTUs per cubic foot, then the heat input would be: Heat Input = CFH x BTU per Cu. Ft. = 5566 x 1050 = 5,844,300 BTUs per Hour Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Figure 1 Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Figure 2 Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Figure 3 Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com LATTNER BOILER COMPANY Low-NOx Boilers Figure 4 Lattner Boiler Company 1411 9th St. SW Cedar Rapids, IA 52404 T: (319) 366-0778 F: (319) 366-0770 W: www.lattner.com