Please participate in the discussion on the usage of platinum mesh in nitric acid plants
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Currently, the price of platinum mesh has started to rebound after reaching a bottom, making it an excellent time for replacement. The platinum mesh used in nitric acid production facilities comes in binary, ternary, and flat-weave types. We are not sure which type is used in your factory (or in any factories you are aware of). Please participate in the discussion by answering the following questions: 1. What is the scale of the facility, and what processing technology is employed? (Our case: 80,000 tons per year, full-pressure process.) 2. What type of platinum mesh is used in the oxidation furnace – binary, ternary, flat-weave, or something else? How many meshes are used in total? (Our case: We use three-dimensional mesh, five meshes in total.) 3. How often is the platinum mesh replaced under normal circumstances? (Our case: Every six months.) 4. What is the wear rate of the platinum mesh? (Our case: The wear rate is 0.102 g per ton of nitric acid produced.) This post was last edited by chen3jun on 2009-3-21 01:14
One set of 270,000 tons per year and one set of 105,000 tons per year, French GP double pressurization； Sanyuan Network ； 105,000 tons/year: 7 sets (one oxidation furnace each), 270,000 tons/year: 14 sets (two oxidation furnaces each) ； Replaced every six months
30,000 tons per year; the ternary mesh needs to be replaced every 2 years – 4 units are required, giving a total capacity of 105,000 tons per year; French GP dual-pressure system； Binary network ； 105,000 tons/year, 6 sets (per oxidation furnace), replaced every six months
Recently, some companies that sell platinum mesh came to our factory and strongly recommended using binary mesh, claiming that we were the only ones in the country still using triangular mesh. It seems that’s not the case though; a piece of binary mesh costs more than 40,000 yuan more than one of triangular mesh. Our triangular mesh should work just fine, so we have no intention of switching to binary mesh. Please continue to participate in the survey!
A binary network is used for the pressurized method, while a ternary network is used for the normal-pressure and low-pressure methods; this is the best approach considering catalytic efficiency, cost, and consumption
We use the 50,000-ton pressurization method with a binary mesh; the operation duration is 80 days, and the consumption is 0.25. We are currently exploring the patterns of mesh usage.
The atmospheric pressure method generally uses a ternary mesh, while the pressurized, double-pressurized, and high-pressure methods generally use a binary knitted mesh. Therefore, the price of the platinum mesh cannot be used alone as the sole criterion for choosing its type. Given the severe pollution caused by the atmospheric pressure method, **environmental protection laws and regulations are becoming increasingly strict, and manufacturers that use this method are currently under great environmental pressure. At present, newly built or planned nitric acid production facilities in China basically adopt the double-pressure method. It is understood that in the international market, double-pressure nitric acid production plants almost all use the FTC catalytic network manufactured by the German company Heraeus. It is said that this catalyst offers good performance, low platinum consumption, and reduced usage of precious metals. However, since it is a patented technology, it is not clear whether it indeed belongs to the binary network type.
The consumption of platinum mesh depends not only on the amount of acid produced; a key factor is that the airflow distribution must be even, otherwise localized excessive consumption may occur； At the same time, offset flow can cause deterioration in the process flow system. It seems that foreign countries still have a greater advantage in terms of technology in this area.
One set of 270,000-ton double-pressing system, one set of 80,000-ton pressing system, two sets of DA540 units using the comprehensive method – all equipped with ternary knitted mesh. Double pressurization: 14 nets ； Pressure: 6 sheets ； Comprehensive method: 6 sheets.
70,000 tons per year, using the medium-pressure process; the platinum mesh consists of a binary structure with wire diameters of 0.076 mm, and both woven and flat-woven types are used. Eight such meshes are employed, with a replacement interval of 3.5 months. The consumption of platinum mesh is 130 mg per ton of 100% nitric acid.
It is a ternary mesh, but its overall metal content differs significantly from that of domestic ternary meshes; it belongs to a composite mesh type, with each mesh having a different metal content
In fact, Platinum Net has a history of over 170 years; there are no issues with either DEC from China National Chemical Industry Corporation’s Taiyuan Precious Metals Division or FTC from Halliburton, and the costs associated with maintenance are low, with minimal initial investment required. The platinum consumption of DEC is around 70 mg.
1. Plant scale and the process used ( ours: 150,000 tons per year, full-pressure process). 2. What type of platinum mesh combination is used in the oxidation furnace. 3. How often does it need to be replaced under normal circumstances (in our case: every six months). 4. What is the loss rate of the platinum mesh (in our case: the loss rate is 0.08 g per ton of nitric acid)
At normal pressure, it is generally replaced every about 1 year; for medium-pressure double-pressurized systems, it is replaced every 6 months; and for high-pressure furnaces, it is replaced every 3 months
At present, the platinum-catalyzed nets used by most nitric acid manufacturers are those made of platinum-rhodium binary alloys; ternary alloys are gradually being phased out. Binary alloy nets have significant advantages in terms of strength and conversion rate.
Many manufacturers are now using Shanghai Pait’s Eco-Cat netting, which is said to be based on technology from British firm SGS. The platinum consumption is quite low, and the ammonia consumption is not very high either.
270,000 tons per year of dilute nitric acid – French GP double-pressure system; each oxidation furnace is equipped with 7 mesh screens, made of binary warp-knitted material; platinum consumption: 120 mg (per ton of 100% nitric acid)
The platinum meshes produced by Kunming Guiyan Platinum Industry are also good; both ternary and binary types are available