TOC Analyzer Pitfalls Part 2
In the first part of TOC analyzer pitfalls, suggestions for avoiding some of the pitfalls related to Sample System in TOC analysis were mentioned. Let’s continue with other components of conventional High Temperature Combustion TC (Total Carbon) / TOC and conventional Process UV/Persulfate TOC analyzers.
Carrier Gas
The carrier gas may be air, nitrogen or oxygen. The presence of an unstable carrier or failure to control the carrier as a critical parameter will badly affect the accuracy of the TOC analyzer’s analysis. The carbon dioxide produced in the oxidation that takes place in the reactor is measured by non-dispersive infrared (NDIR) technology as a volume percent of the total gases that are emitted by the reactor. Thus, variation in the carrier gas flow will induce an error in the TOC analyzer’s analysis. In order to avoid this pitfall, a Mass & Flow Controller can be used. In terms of maintenance, loss of carrier gas can adversely affect the components of the TOC analyzer. In the UV/ Persulfate Reactor, this loss would mean that the corrosive persulfate, acid and sample would be forced up into capillaries, pressure gages and flowmeters.
Reactors
Reactors
UV/Persulfate Reactor
The UV lamp is the most important component of a UV/PERSULFATE reactor. The TOC analyzer’s UV lamp should be able to completely break the bond between the carbon atoms and should be able to produce an oxidation reaction in which all the carbon is converted into carbon dioxide. For this, a power spectral density of 185 nm and 254 nm is required which the TOC analyzer manufacturers must provide. Insufficient UV energy will affect the calculations in TOC analysis.
High Temperature Combustion Reactor
A high temperature combustion reactor has more maintenance requirements and failure modes than the UV/Persulfate Reactor. Furnace temperature control and monitoring features from the TOC analyzer are required. The ‘overtemprature’ alarm should go off and shut down must occur as this prevents reactor/furnace assembly destruction. Catalyst poisoning monitoring is important as it can cause an error in the results of TOC analysis. You should also be aware of the condition of the reactor assembly and problems like reactor clogging. Monitoring of the reactor assembly will help in locating sub-system leaks and condition of the structure within the TOC analyzer. Neglecting reactor assembly monitoring will result in destruction of components and loss of data.
[...] the second part of TOC analyzer pitfalls, the pitfalls relating to carrier gas used in TOC analyzer’s analysis and reactor of High [...]