What type of heat exchanger is effective for flue gas at around 300 degrees?
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A company owns 26 various types of kilns, but the flue gas temperature is only around 300 degrees. Apart from using it for drying raw materials, what other ways are there to make better use of this waste heat? If all the flue gas is utilized in a waste heat boiler to generate steam, could electricity be produced, in addition to steam for industrial and domestic use? This post was last edited by lizhongjun2008 on 2008-10-9 11:15.]
For such temperatures, a heat pipe heat exchanger is the most suitable option, as it is appropriate for recovering heat sources in the range of 200–400 degrees. If the heat source exhaust gas you intend to recover comes from a kiln, the heat-exchanged hot air can be fed into the kiln as secondary air, which helps save energy and reduce operating costs.
In addition to the above uses, it can also be used for heat exchange with water, utilizing the hot water for industrial or domestic purposes.
A shell-and-tube heat exchanger can be used, with flue gas flowing through the shell side to heat the water inside the tube side. The heated water can be used to supply hot water for the employees’ bathrooms, allowing them to take baths, which helps save energy and improves overall efficiency. Additionally, if there is an excess of hot water, it can be sold to bathhouses in the community, thereby increasing the organization’s income. It’s a win-win situation.
In that case, the flue gas flows through the shell side and is used to heat the water inside the tube side, which makes scaling more likely; there is so much dust in the flue gas
Original poster, it would be best if you could tell us the composition of the smoke, as well as whether steam or hot water is needed; only then can we come up with a reasonable solution.
This is an energy-saving and emission-reduction project carried out by our company; currently, the client has not provided any detailed information. Refractory tunnel kilns that use water gas as fuel, with flue gas temperatures of 300 degrees; there are multiple such kilns. Some of the waste heat from the flue gas is utilized as heat for raw materials, while the remaining waste heat is intended to be recovered using waste heat boilers or high-efficiency heat exchangers. However, I am not very familiar with heat exchangers suitable for this temperature range, and I hope everyone can offer some help.
Several possible solutions: 1. Use a heat pipe heat exchanger to heat the combustion air； 2. Install a waste heat boiler to produce steam. (Production of 10bar steam should be considered.) ； 3. Produce hot water. However, attention must also be paid to the corrosion issue on the flue gas side at low temperatures.
Water-tube heat exchangers can be used to produce steam or hot water; if steam is required, steam at 1.3 MPa can be generated, and if steam is not needed, hot water can be produced for residential heating.
Given that the project involves flue gas from kilns, it is unlikely that the heat source is for domestic use, as kilns are generally located at a distance from residential areas. It is recommended to use heated air supplied to the furnace, as this can improve combustion efficiency, reduce fuel consumption, and help achieve emission reduction.
Install an air preheater so that hot air can be fed into the furnace; this improves combustion efficiency, reduces fuel consumption, and lowers the exhaust gas temperature.