By CC 2019-10-23 09:22:57
Small gas boiler burner selection method
1, the basic principles of burner selection
1. According to the fuel type used by the user, the gas commonly used in China is divided into two categories: natural gas and artificial gas according to the acquisition method. The gas used should have composition and calorific value analysis report;
2. Select the type of burner according to boiler performance, furnace structure and flue gas emission requirements;
3. The output heat power of the burner should be matched with the rated output of the boiler. The shape of the flame, such as the length and diameter, should be compatible with the structure of the furnace;
4, the burner adjustment range should be large, should be able to adapt to the needs of boiler load changes, to ensure complete combustion under different conditions;
5. Flue gas emissions and noise must meet the requirements of environmental protection. The main pollutants for flue gas emission control include: particulate matter, sulfur dioxide, nitrogen oxides, mercury and its compounds, blackness of flue gas, and discharge requirements in addition to comply with GB13271 In addition to the air pollution emission standards, it is also subject to local environmental protection restrictions;
6, should choose a simple structure, reliable operation, easy to adjust control and maintenance, high control of the burner;
7. Comprehensive comparison of burner brand, cost performance, service life and after-sales service;
8. In addition to the resistance of the customer service boiler body, the wind pressure of the combustion should also overcome the resistance of the energy saver and the flue gas system.
2, burner selection
2.1. The following basic parameters should be determined before selecting the burner correctly.
1. Local environmental protection restrictions on boiler smoke pollutant emissions;
2. The heat output of the burner, the rated thermal power of the boiler, and the heat value of the hot road and gas under the rated working condition of the boiler;
3. The resistance of the combustion chamber (the back pressure of the furnace), the energy saver and the flue gas system during normal operation of the boiler.
4. The calorific value of the fuel (generally calculated according to the low calorific value, there should be an analysis report)
5, gas pressure before the valve
2.2, the choice of burner type
At present, small boiler burners generally use two types of combustion, diffusion combustion and premixed combustion, and generally select combustion methods according to boiler load size and flue gas emission requirements. Burners produced by different burner manufacturers have different furnace types. The user or designer should fully communicate with the burner supplier to confirm the burner operating parameters, the furnace structure and size requirements, and the low nitrogen type. The burner must also confirm the NOx emission index to avoid ambiguity or supply and demand disputes during use.
2.3, burner output thermal power confirmation
The output heat power meter of the burner corresponds to the fuel consumption of the boiler. The fuel consumption of the boiler is calculated according to the rated thermal power and thermal efficiency of the boiler: the output heat power of the burner = (1.1-1.15)* The rated thermal power of the boiler / filtration Thermal efficiency
Note: The rated thermal power of steam boilers is calculated at 700 kW per ton.
2.4 Selection of burner working points
According to the burner operating characteristic curve provided by the burner manufacturer, the burner output thermal power is taken as the abscissa, the combustion chamber pressure (furnace back pressure) is taken as the ordinate, and the intersection point is marked as the full load working point on the working characteristic curve. This point should fall within the corresponding full load working area, and the closer to the right side boundary, the more ideal, so that the burner is more economical and can ensure a larger adjustment space for the partial load point and the full load point.
2.5, the choice of burner model
After the burner full load working point is determined, the model marked with the working characteristic curve can be selected, and the selected burner is tentatively selected. In addition, determine with the supplier whether the geometry of the burner flame matches the combustion chamber. If the combustion chamber is too small, the flame will directly wash the heated surface, the fuel will be quenched, the combustion will be incomplete, the boiler thermal efficiency will be reduced, the flue gas partner will exceed the standard, and the carbon on the heated surface will affect the stable and safe operation of the boiler; the combustion chamber is too large and the flame fullness is poor, resulting in The combustion chamber temperature is low, which affects the effective heat transfer of the heated surface.
On the other hand, it is worth noting that the burner output provided by the general data is calculated for an altitude of 100 m, an ambient temperature of 20 ° C, and an atmospheric pressure of 100 kPa (1 atm). For high altitude areas, atmospheric pressure is low, air is thin, and the oxygen content in the air is lower than in the plain area, and should be fully considered when selecting the burner. Burners designed under standard conditions, when operating at high altitudes, the oxygen content in the air and the pressure of the fan are reduced, resulting in incomplete combustion, reduced combustion temperatures, reduced thermal and thermal efficiencies, and increased CO emissions, such as If certain measures are not taken, it will inevitably affect the operation of the boiler. Therefore, the ambient air temperature, altitude, and the burner should be calculated when the burner is selected, and whether the selected burner can be burned normally in the local area.
2.6, gas valve selection
According to the heat of the low heat of the fuel, the output heat of the burner, the pressure of the gas supply, the pressure of the combustion chamber (the back pressure of the furnace), the reference table of the gas valve group diameter, the valve diameter is selected, and some manufacturers will also be equipped with different voltage regulators. The valve spring is adapted to different pressure-receiving pressure ranges. The user selects the spring specification of the pressure-regulating valve according to the approximate pressure value before the solenoid valve inlet (note the pressure value given in the general table, plus the back of the furnace).