Flue gas desulfurization by wet method followed by whitening process route for coke ovens
Thread Content
Current environmental regulations require that wet flue gas desulfurization should not produce any white smoke (vapor); therefore, whitening systems are needed. Theoretically, when the flue gas temperature is around 65 degrees, it would be more energy-efficient to first cool the gas to remove the condensed water before reheating it. What are everyone’s thoughts on this? Does anyone have any successful experience in this area?
For the wet flue gas desulfurization in our boilers, a water washing step was added to eliminate whitening; the results were satisfactory, and the environmental protection agency approved it
Can steam be eliminated by simply washing with clean water, or by cooling the spray water using a heat exchanger to increase the amount of spray water? Please explain how you do it. Thank you
The commonly used whitening methods can be divided into two categories: First, flue gas heating – the desulfurized flue gas is heated from 45–55°C to 70–80°C; this process is affected by the humidity of the flue gas, as well as the ambient temperature and humidity. II. Direct mixing of flue gas: The desulfurized flue gas is mixed with a certain proportion of air (or hot air) to achieve the effect of eliminating whiteness. We have adopted measures: there are two options. The first is to cool and dehumidify the wet flue gas first, and then use a gas-liquid separator to eliminate the whitening effect of the flue gas.
High-efficiency blade separator technology: High-efficiency vertical blade separators are capable of handling conditions with a very high gas-liquid ratio, especially in situations where excessive amounts of liquid entrainment can lead to slug flow. Advantages: Higher liquid separation efficiency, wider operating range with flexibility, suitable for applications with high gas-liquid ratios, suitable for situations involving slug flow, and easy to retrofit existing vertical separators
High-efficiency blade separator technology: The size of the container housing required for designing efficient separation blades is typically 20-30% smaller than that needed with traditional mesh designs, which means lower investment costs and less space requirement. The high-efficiency separation blades are made of smooth stainless steel, making them resistant to damage and clogging. The costs associated with their daily operation, maintenance, and shutdown for repairs are very low, and their service life is much longer than that of traditional wire meshes.
Whitening is a current hot topic and also our main business area. The commonly used method for this purpose is condensation reheating, which meets the environmental regulations in many regions. In many places, environmental regulations only set requirements regarding the condensation temperature; this approach can indeed reduce pollution emissions, but it cannot achieve complete whitening. If whitening is required, the flue gas needs to be heated again.
Based on the current actual operating conditions, even when heated to 70–80°C, the steam cannot be eliminated
The dew point of exhaust gas is generally above 130 degrees Celsius, so it needs to be preheated to above 130 degrees Celsius!
It needs to be considered in conjunction with the saturation curve; it is related to many factors, and complete whitening is achievable