The newly launched Nernst 1735 acid dew point analyzer is a special instrument that can measure the acid dew point temperature in the flue gas of boilers and heating furnaces online in real time. The acid dew point temperature measured by the instrument can effectively control the exhaust gas temperature of boilers and heating furnaces, reduce equipment low-temperature sulfuric acid dew point corrosion, improve operating thermal efficiency, increase boiler operating safety and extend equipment life.
After using Nernst 1735 acid dew point analyzer, you can accurately know the acid dew point value in the flue gas of boilers and heating furnaces, as well as oxygen content, water vapor (% water vapor value) or dew point value and water content (G grams/KG per kilogram) and humidity value RH. The user can control the exhaust gas temperature within a certain range slightly higher than the acid dew point of the flue gas according to the display of the instrument or two 4-20mA output signals, so as to avoid low-temperature acid corrosion and increase the safety of boiler operation.
In industrial boilers or power plant boilers, petroleum refining and chemical enterprises and heating furnaces. Fossil fuels (natural gas, refinery dry gas, coal, heavy oil, etc.) are generally used as fuels.
These fuels contain more or less a certain amount of sulfur, which will produce SO2 in the process of peroxide combustion. Due to the existence of excess oxygen in the combustion chamber, a small amount of SO2 further combines with oxygen to form SO3, Fe2O3 and V2O5 under normal excess air conditions. (flue gas and heated metal surface contain this component).
About 1 ~ 3% of all SO2 is converted to SO3. SO3 gas in high-temperature flue gas does not corrode metals, but when the flue gas temperature drops below 400°C, SO3 will combine with water vapor to generate sulfuric acid vapor.
The reaction formula is as follows:
SO3 + H2O ——— H2SO4
When sulfuric acid steam condenses on the heating surface at the tail of the furnace, low-temperature sulfuric acid dew point corrosion will occur.
At the same time, the sulfuric acid liquid condensed on the low-temperature heating surface will also adhere to the dust in the flue gas to form sticky ash that is not easy to remove. The flue gas channel is blocked or even blocked, and the resistance is increased, so as to increase the power consumption of induced draft fan. Corrosion and ash blockage will endanger the working condition of boiler heating surface. Since the flue gas contains both SO3 and water vapor, they will produce H2SO4 vapor, resulting in the increase of acid dew point of flue gas. When the flue gas temperature is lower than the acid dew point temperature of the flue gas, H2SO4 steam will adhere to the flue and heat exchanger to form H2SO4 solution. Further corrodes the equipment, resulting in heat exchanger leakage and flue damage.
In the supporting devices of the heating furnace or boiler, the energy consumption of the flue and heat exchanger accounts for about 50% of the total energy consumption of the device. The exhaust gas temperature affects the operating thermal efficiency of heating furnaces and boilers. The higher the exhaust temperature, the lower the thermal efficiency. For every 10°C increase in the exhaust gas temperature, the thermal efficiency will decrease by approximately 1%. If the exhaust gas temperature is lower than the acid dew point temperature of the flue gas, it will cause equipment corrosion and cause safety hazards to the operation of heating furnaces and boilers.
The reasonable exhaust temperature of heating furnace and boiler should be slightly higher than the acid dew point temperature of flue gas. Therefore, determining the acid dew point temperature of heating furnaces and boilers is the key to improving operating thermal efficiency and reducing operating safety hazards.
Post time: Jan-05-2022