Considerations for selecting a chimney for a heat transfer oil furnace
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Hello everyone: Our company has 3 furnaces with a capacity of 12,000 kcal each. These furnaces currently use 70-meter-high red brick concrete chimneys. Due to the use of wet sulfur removal methods, the concrete has begun to leak and corrode, resulting in the formation of many white crystals on the outer surface of the upper part of the chimneys. Therefore, the company is considering replacing it with a fiberglass chimney or a chimney with a carbon steel core and stainless steel lining. I would appreciate guidance on the advantages and disadvantages in terms of cost-effectiveness and applicability.
A layperson, offering some preliminary thoughts to stimulate further discussion. Is this a coal-fired boiler? The process in which the flue gas after combustion undergoes wet flue gas desulfurization before being discharged through the chimney? What are white crystals? Is red brick corrosion acidic corrosion? What is the temperature of the flue gas? What is the flue gas flow rate? Brick construction is the cheapest option for 70 meters in height. FRP needs a steel frame for support and fixation; it is resistant to corrosion but not to temperature changes. What is the process of lining carbon steel with stainless steel? How can layer corrosion be addressed? The cost is also the highest
Thank you for the guidance; I have no experience in chimney design. The leader gave a task, and I’m forcing myself to carry it out. The white crystals are likely sodium salts. Sample names: Ca mg/L, K mg/L, Mg mg/L, Na mg/L, Al mg/L, Cu mg/L, Fe mg/L, Ni mg/L, Pb mg/L, Zn mg/L. Top layer: 22000, 2600, 9070, 118000, 3910, 56, 4630, 60, 53, 208. Inner layer: 39600, 1070, 350, 4860, 4230, 59, 3170, 8, 273, 33. Middle outer layer: 1530, 4840, 9000, 84000, 19700, 179, 449, 84, 66, 884. The flue gas temperature is around 110; the gas flow rate is unknown
In the same spirit of offering suggestions for further discussion, our company’s heat transfer furnaces use natural gas, and the chimneys are made of stainless steel
What desulfurization process, at a temperature of 110°C? How long has the brick-concrete chimney been in use? I can give you a reasonable suggestion regarding fiberglass chimneys.
Is the inner lining of a brick-concrete chimney made of fiberglass?
It’s better to switch to stainless steel right away; we use stainless steel anyway, so it’s a one-time solution.
Fiberglass chimneys do not have sufficient temperature resistance, and chimneys with a carbon steel lining and stainless steel interior also seem to be inadequate in terms of preventing corrosion. The anti-corrosion method using ND steel + glass phosphide sheets can be employed, or the Savrin anti-corrosion method can be used.
From the perspective of a layperson, and considering the actual conditions in my workplace, it is likely that the main component of these white crystals is sodium sulfate. NaOH is commonly used for sulfur removal through wet methods; in the absence of a rapid cooling process, the flue gas often contains a large number of crystalline particles； As far as I know, the heat resistance temperature requirement for fiberglass-reinforced plastic materials is below 90°C. The furnaces in our company were designed by foreigners, and the desulfurization section at the rear is made of fiberglass-reinforced plastic; it is explicitly required that the temperature be kept at ≤90°C.
There are many such processes: fiberglass, carbon steel, and titanium alloy for lining concrete chimneys
In wet flue gas desulfurization, the temperature at the exhaust gas outlet is usually very low, so fiberglass can be used entirely; in addition, three steel pipes can be employed to create a triangular pyramid-shaped support structure