Is there any problem if the temperature of natural gas flue gas is reduced to less than 100 degrees?
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Dear friends, after using natural gas as fuel for heat exchange, due to process reasons, the flue gas temperature is maintained at around 230°C, which is a huge waste of emissions. Neng Yi can consider that since natural gas is a very clean energy source, there is basically no SO2 in the flue gas, and there is no problem of low-temperature SO2 condensation and corrosion of materials. He wants to use the waste heat in the flue gas to heat the air and reduce the use of natural gas. Please discuss, can the flue gas temperature be within 100°C, and what is the economics? If you have implemented it before, please tell us about your experience in this area. Thanks.
Theoretically, it can certainly be done, by preheating the air, preheating the fuel, or preheating the hot water, etc.! But I didn't do it!
In this situation, using a heat pipe heat exchanger is the best choice. Our factory produces this kind of heat exchanger. If you are interested, please contact me.
It is perfectly fine to add a condensation heat exchange device behind the smoke exhaust outlet. To put it bluntly, it is just a heat exchanger. Boilers for hot water and heating are now generally equipped with this device, and the theoretical thermal efficiency can reach 100%, saving energy and reducing consumption.
If there is no dew point corrosion, it should be OK, but the poster said there is no SO2 corrosion, so if there is other corrosion, it still needs to be considered.
Theoretically it's possible, just add a flue gas condenser at the end~! This is generally done.
Absolutely, the economy can be guaranteed.
It is possible to reduce the exhaust gas temperature to less than 100°C, but the heated air temperature must be below 80°C. It would be better if water is heated, because it is easy to achieve. The heated air preheater will be very large and uneconomical.
The exhaust gas temperature of our thermal storage condensing boiler is lower than 60 degrees. You can totally do that!
It can be achieved by adding a preheater for heat exchange and preheating the air. I would like to ask a question, is there any relationship between the flue gas temperature and whether smoke exhaust is mandatory?
The temperature to which the flue gas can be reduced after burning various fuels should be determined based on the dew point temperature of the flue gas after combustion. It should generally be about 20 degrees higher than the dew point temperature.
Yes, by adding a condensing heat exchanger, the overall comprehensive thermal efficiency can reach 105% (according to China's thermal calculation standards). From the perspective of energy saving, it is also in line with* * requirements. Even if there is a small amount of S in the flue gas, the condensed water produced will be corrosive, and there are also NO compounds. Therefore, the added heat exchanger must consider corrosion issues and pay attention to material selection. At the same time, the discharge of condensed water must also be considered, and it must be treated before being discharged.
If it is to heat air and drop it below 100 degrees, you should determine the air flow rate based on the flow rate and temperature of the flue gas. Since the latent heat of vaporization in the flue gas is relatively high, a large amount of heated air is required. Moreover, just blindly pursuing lowering the exhaust smoke temperature will increase the investment and operating costs of the equipment. A comprehensive economic cost ratio needs to be carried out to determine the optimal point.
Sir, you have to think about it. Have you ever measured the sulfur content in natural gas? Don’t just speculate. Almost all natural gas contains sulfur, but the amount varies. The flue gas contains 500ppm sulfur, and dew point corrosion can occur at about 130 degrees. It is feasible to add an air preheater, but it depends on the S content in your flue gas. If 130 degrees is the dew point, the design temperature of your flue gas must be 150 degrees anyway (it reaches the dew point when it's windy, rainy, or snowy). From 230 to 150 degrees, you have to carefully calculate how much heat you can recover and how much you have to invest in the entire flue gas circulation system such as preheaters and fans. Besides, even if there is no S in the flue gas, the flue gas temperature cannot be too low. If the flue gas temperature is too low, either increase the height of the chimney or add an induced draft fan, and the cost must be carefully calculated.
Heating hot water should also work. Is it cost-effective? How to calculate?