Cast iron plate air preheater
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In refinery tubular heating furnaces, shell-and-tube and heat-pipe air preheaters are widely used; the increase in sulfur content in the fuel leads to a decrease in the dew point temperature, resulting in severe corrosion. It is understood that cast-iron plate air preheaters are widely used in foreign technologies; what is the principle behind their corrosion resistance? How is the exhaust temperature determined? How are the service life and investment of this equipment calculated?
This post was last edited by dongjiang1001 on 2011-11-8 at 14:24. It is sufficient to keep the exhaust gas temperature 20 degrees above the dew point temperature.
The plate-type air preheater is primarily an exchanger used for gas heat exchange; it is employed to recover heat from flue gas, heat the combustion air, and save fuel gas. It can function as a preheater in flue gas with temperatures as high as 760 degrees. The function of an air preheater is to recover heat and reduce consumption; it is primarily used in hydrogen production converters or cracking furnaces in large chemical enterprises, as well as in devices that convert raw materials such as natural gas, refinery petroleum gas, and naphtha into hydrogen, serving as a heater for the combustion air. It has a wide range of applications and has already replaced traditional tube-sheet air preheaters and heat-pipe air preheaters abroad. Wide range of applicable fuels: natural gas, liquefied petroleum gas, naphtha, coal, sulfur recovery, etc. Application prospects: Technical advancements in large-scale chemical plants have opened up new possibilities for the use of plate-type air preheaters. The construction of hydrogen production facilities with a capacity of over 100,000 M3 makes plate-type air preheaters an essential choice, as tubular air preheaters are too large to be installed in such facilities. The flat air preheaters produced by the Dutch company APEX have demonstrated excellent performance in large-scale projects such as Nanjing Yangba Company, Shanghai BASF Ethylene, CNOOC’s 800,000-ton urea plant, CNOOC’s 600,000-ton methanol plant, and Qinghai Zhonghao’s 600,000-ton methanol plant. Advantages of plate-type air preheaters: compact structure with an elastic design that prevents thermal expansion; a wide range of material options, including carbon steel, stainless steel, cast iron, glass, etc.; no need for maintenance, with a service life of up to 30 years; small size, suitable for large-scale installations, occupying only 1/3 of the volume of tubular air preheaters. It features high heat exchange efficiency and a wide range of applicable fuels.
The explanation is very detailed; I’ve learned from it, thank you!
This post was last edited and replied to by dongjiang1001 on 2011-8-22 08:26. Reply 1# cpedl2007: Our company has developed a new type of air preheater made of rare earth alloy and finned plates, by drawing on foreign technologies related to cast iron air preheaters. It effectively prevents low-temperature dew point corrosion. Please leave your email address and I’ll send you the materials.
This post was last edited by zgj2405 on 2011-11-27 at 12:00. Are there any practical application examples? Could the person at Haidyou on the 6th floor send some information to my email? Thank you!
This post was last edited by zgj2405 on 2011-11-27 at 12:00. Friend on floor 6, in terms of cast iron materials, their resistance to acid corrosion is not very good; therefore, some cast iron components are protected using anodic protection. I’m curious about the acid resistance of the new rare earth alloys you mentioned – are there any relevant test data available? I’m interested in your products; if you have any related information, please send it via EMAIL. Thank you!
What is the plate thickness of the cast iron finned plate air preheater? What is the maximum pressure difference that can be tolerated between the air and the flue gas?
Reply to 1# cpedl2007 to view the short message.
Our company’s 1 million-ton natural gas methanol plant uses plate-type air preheaters imported from the United States. The pressure drop and temperature levels do not meet the design specifications. When the plant was put into operation in July of this year, at 70% load, the pressure drop on the air side reached 2100 Pa (the designed value being 1100 Pa), while the pressure drop on the flue gas side reached 2000 Pa (the designed value being 1500 Pa). The induced draft fan reached its maximum speed at 75% load, and it is no longer possible to increase the load any further. The flue gas exit temperature is above 240 degrees. Could everyone please help analyze this? Thank you:victory:
Consider checking the seal of the partition to see if a poor seal between the flue gas and air is causing an increase in resistance.