Why cannot plate heat exchangers be used in the absorption towers of large and medium-sized acid production plants using smelting flue gas?
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This post was last edited by in the blink of an eye on 2018-7-7 at 20:58. The use of heat exchangers plays an important role in improving the purification process; lead intercoolers are now rarely seen. In earlier years, when in the blink of an eye was working in a factory, one acid production facility used an air-filled intercooler process for purification. The application of plate exchangers in the sulfuric acid drying process was not so successful; Daye Nonferrous Metals once used plate exchangers, but corrosion and perforation of these exchangers occurred shortly after their use. In 2005, when I was leading a team at Daye Plant*, I saw the old acid production equipment’s waste plate frames (without plates installed). At that time, Daye was still using C276 material, while for the second-phase dry absorption project at Jinlong Copper Industry, heat exchangers made of Hastelloy D205 were employed. Since the acid temperature is above 90 degrees, welding (laser welding) can only be used on the acid side. Subsequently, 2 plate exchangers made of material D205 were also purchased for the ADB project at Tongling Jinchang Smelting Plant (formerly Tongling Non-ferrous Metals Second Smelting Plant). About a year after the new sulfuric acid system for the ADB project at the Tongling Jinchang Plant was put into operation, blockages were detected in the plate exchangers. Despite installing backwash circuits, the resistance of these exchangers continued to increase, and ultimately it was necessary to replace them with shell-and-tube type anodic protection acid coolers. It can be said that the D205 plates used by Jinlong Copper Industry have a longer service life, but they were also replaced in 2006 with shell-and-tube anodic protection acid coolers. Recently, during a visit to factories in the industry, I saw the plate exchangers used in absorption towers on site, and I was extremely surprised at that time.
During the project feasibility study phase, it is important to visit as many sites as possible to examine the equipment setups at large and medium-sized factories in the industry and to learn from their experiences and lessons. Under no circumstances should you skimp on that little amount spent on travel expenses – avoiding redundancy can save millions, even tens of millions!
It’s just that there aren’t many hardworking technicians like you in China; otherwise, ZTE wouldn’t be in such a situation!
We have been using plate exchangers for dry absorption for many years now
Using a plate exchanger in the drying tower is no problem; since the acid temperature is low, a detachable plate exchanger can be used. Plate exchangers are rarely used in the absorption towers of large-scale acid production plants.
If the sealing strips used in plate exchangers can withstand higher acid temperatures, such as gaskets that can resist 120 degrees, then there is no problem using detachable plates in the absorption tower. Not long ago, in the factory, the absorption tower plates were replaced to enable acid-water exchange; the original water side was converted to the acid side, and fluororubber gaskets were used. However, whenever the flue gas load decreased, the plate exchanger began to leak water and acid, and the problem resolved again once the load increased.
Most inspections these days are led by managers, and they usually concern equipment for which a decision has already been made. There isn’t much genuine effort in conducting the kind of inspections you mentioned; ultimately, it comes down to the influence of technical personnel, with some even sticking to their previous habits
We originally used anodic protection, then switched to plate exchange – but we faced problems with clogging, long maintenance times, and high costs for the rubber strips; eventually we returned to anodic protection.
We use a heat exchanger for acid cooling; the acid that comes out of this heat exchanger passes through another plate heat exchanger before going to the final acid tank
On what scale is acid production carried out? For example, what is the annual acid production volume?