Condensation principle
The composition of natural gas is 99% methane (CH4), containing a large number of hydrogen (H), after combustion of flue gas contains a large number of water steam, by theoretical calculation, the water steam in the flue gas accounted for about 18%; The proportion of water steam in the flue gas after combustion of diesel boiler is about 12%. If water vapor is condensed into water, the latent heat of vaporization is recovered, and the potential of heat recovery is very large. The recovery method is to install a condenser for the boiler, so as to convert the traditional boiler directly into a condensing boiler.
Usually the efficiency of a boiler is calculated in terms of a low calorific value. When a conventional boiler has a calibrated thermal efficiency of 90%, this efficiency corresponds to a low calorific value. Condensing boiler is also in accordance with the low calorific value to calculate its thermal efficiency, its initial thermal efficiency reaches 95~96%, plus the condensation release of about 5% of the latent heat (in the case of the latent heat of water steam is fully used 40~50%), condensing boiler can improve the thermal efficiency of the boiler to more than 100%.
Condensing boiler design concept
1. Condensing system design
The design criterion of condensing boiler is to control the flue gas temperature below the dew point temperature.
Steam boiler condensation system
1 If the feed water temperature is 20℃, the feed water enters the boiler after being preheated by the condenser, and is connected with the boiler in series. The condenser is used as the preheating device of the boiler feed water.
2: If the feed water temperature reaches 104℃(thermal deaeration is adopted), the condenser is designed as an independent system form, and the soft water (20C) not fed into the deaerator will exchange heat with the flue gas to achieve the purpose of flue gas condensation.
2. Material design of condenser
The products of oil and gas combustion contain harmful substances such as SO2 and NOx, which dissolve in the flue gas so that the condensate has strong acidity. So the condensate waste heat recovery device must use corrosion resistant materials. Our company's condenser tube uses the most ideal "sulfuric acid low temperature dew point corrosion resistance" special steel ND steel, acid corrosion resistance, chloride ion corrosion resistance is excellent. Corrosion resistant asphalt paint is sprayed on the surface of condenser flue steel plate in contact with flue gas.
3, condensate water recovery and discharge
Boiler emissions mainly include COx, NOx, SOx, among which NOx, SOx can form acid rain; CO2 can form a greenhouse effect. Therefore, it is very important to control the emission of atmospheric pollutants from boilers. On the one hand, condensing boilers reduce pollution emissions due to their high efficiency and fuel consumption. On the other hand, condensed water can absorb part of COx, NOxSOx, greatly reduce the emission of pollutants. Because the condensate is acidic, you can set up a neutral pool to discharge the condensate into the neutralization pool, and check the PH value of the neutralization pool regularly.
Structural characteristics of condensing boiler
Boiler body structure characteristics
1. The overall layout of WNSL condensing boiler adopts horizontal wet back structure, low position of the combustion chamber center, symmetrical distribution of heat exchange smoke pipe, uniform and stable heat transfer load, which is conducive to the working medium side of the water circulation, to minimize the occurrence of water shortage accidents, improve the safety of the boiler.
2. The reasonable application of corrugated furnace liner and threaded smoke pipe to strengthen heat transfer element not only strengthens turbulent heat transfer of high temperature flue gas but also effectively absorbs thermal expansion and cold contraction of furnace body
3, the boiler adopts large furnace bladder, large pot shell, the maximum heating surface, complete combustion, not easy to accumulate carbon, fuel saving, has the characteristics of high efficiency, strong overload capacity.
condenser
1, arranged on the top of the boiler, compact structure, no floor area
2, countercurrent layout structure, heat exchange temperature difference, good heat transfer performance
3, the use of special ND steel material, good resistance to condensation water corrosion, greatly improve the service life
4, adopt reasonable flue structure, condensate water is easy to discharge collection and treatment
Automatic control system
1, the use of burner PID regulation technology, configuration of European imported burner, to achieve the best configuration of air fuel ratio, so as to achieve the full combustion of fuel
2. The boiler water supply adopts frequency conversion water supply mode. By changing the running frequency of the pump motor to change the water intake at the same time, the power of the pump is changed to achieve energy saving water supply and reduce power consumption.
