Advanced CAE provides a one-stop shop for all your analysis needs, from FEED, design, factory manufacturing, commissioning, start-ups, supplying of spare parts and upgrading to on-site maintenance. We also offer specially formulated practical training programs for specific applications.
An Analyser System consists of analyser, process, take off point, sample probe, sample transport line, sample conditioning system, calibration system, sample disposal, analyser shelter/cabinet/rack/pipe stand, power distribution, signal handling, analyser shelter safety system, utilities handling and distribution, etc. Hence it is a Total System.
Advanced CAE is an independent system integrator free of any preferential ties to major analyser vendors. As a result, we retain the flexibility to manufacture our systems with any analyser vendor that our customer selects. Upon understanding our customers’ requirements, we will select the best features within the analyser to deliver the best all-rounded solution for each application.
Although most analysers are designed and built to install in the field without further protection, grouping of analysers together in one shelter has become more popular. Installing equipment in an analyser shelter protects the analysers against adverse ambient condition that may cause errors in the analyser readout. Grouping analysers in this manner also leads to easier maintenance than with separately installed analysers.
The great advantages of choosing a pre-fabricated analyser shelter are that the complete, assembled analyser systems are pre-piped and pre-wired to all the analysers and sample conditioning systems. All necessary utilities and power distributions are also pre-installed at the factory. The complete, assembled system are then fully tested with test gases and shipped to site as a single package. By doing all of this at the factory minimum site installation work is required and our customers save themselves valuable time.
A Sample Conditioning System is designed and built to provide the correct process parameters to the analyser, which can control the process at optimum efficiency to produce on specs end products. The primary objective of a Sample Conditioning System is to extract sample from the process stream and deliver it to the process analyser to ensure that:
A Sample Conditioning System is made up of various components like pumps, pressure regulator, filter, flowmeter, heat exchanger, etc. in a sequence specific for the analyser and sample process condition.
Atmospheric balancing is a technique applied for adjusting the sample pressure to atmospheric pressure where the sample pressure is expected to fluctuate. It is commonly used for process gas chromatograph analyser applications. This can be done by installing a solenoid valve to block the sample to the analyser and another 3-way solenoid value to vent the sample to atmosphere before sample injection.
As analysers are relatively expensive, such as process gas chromatographs, in order to save some cost such analyser systems are designed to use a multi-stream switching system. However, possibility of cross contamination between different streams is highly possible.
One way to eliminate cross contamination is to incorporate “Double Block and Bleed Systems” into the Sample Conditioning Systems. This type of system uses two air-operated valves (AOVs) for each stream. When the valves are de-energized, the tubing between them is vented to the atmosphere, thus preventing contamination. A secondary bypass is used to scavenge all sample lines, keeping all samples current. The double block valve is to prevent sample contamination to the other streams in case the first valves leaked.
For gas samples, Electrical or Steam Heating/Tracing is applied to the sample lines or Sample Conditioning System components to maintain the sample above its dew point otherwise condensation may occur.
As the process line has a higher fluid velocity at the centre, by installing a sample probe to at least one third of the pipe diameter there will be turbulent mixing. This method of sampling is more likely to give better representative process data and rapid responses to the process changes to the analyser. It also eliminates the possibility of suspended solids in the sample which tends to travel from the pipe walls.
Pressurization is the process of supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapour, a combustible dust or an ignitable fibre. Basically, there are three types of pressurization as below:
Basic requirement as type Z pressurization must be satisfied and in addition, a cut-off switch shall be incorporated to de-energize power automatically from all circuits within the protected enclosure not approved in Division 1 upon failure of the protective gas supply. The cut-off switch shall supply an alarm signal output from the protected enclosure.
(Information extracted from NFPA496 “Standard for Purged and Pressurized Enclosure for Electrical Equipment)
Normally, prior to commissioning phase, a pre-commissioning activity is carried out to demonstrate that all analysers are calibrated and providing reliable data with the certified test standards. During the plant’s initial start-up, the process sample should not be introduced immediately into the Sample Conditioning System since it may not cope with unstable plant conditions. When the plant condition is reasonably stable, before putting the sample into the Sample Conditioning System, it is good practice to commission the fast-loop system first to flush the sample back to the return lines. Then commission the system to prevent the possibility of analyser failure and downtime.
The Plant Laboratory has always been the Quality Control benchmark point and it is difficult to convince people to change their mindset. It is unfortunate that operations team are likely to believe the laboratory results even though the on-line analyser may be correct. In such circumstances, the following factors should be evaluated:
As analyser calibration is one of the criteria for maintaining high reliability and confidence for the operation personnel in operating a process plant; a calibration schedule is usually established after plant start-up. For an initial start-up, analysers may be calibrated with test standards at least twice a month and drop to once a month when operation is confident on the reliability of that analyser.
Usually the HVAC pressurization fans are sized to achieve the required shelter pressure as specified. A common problem is due to heavy leaks of pressurization through the analyser doors and panels. This leak is normally significant for small shelters and needs rectification immediately before pressurization is achievable. The second common problem lies in the over-sizing of the shelter louver, which can be eliminated by adding weights to limit the air flowing out of the shelter. Precaution must be taken to ensure that the required Air Changes inside the shelter are maintained.
Our engineers are experienced in handling analysers and are able to conduct training sessions for our client in their usage. We can also engage the analyser vendor to conduct specific training for clients upon request.
A process analyser is a rather unique electronic instrument that operates on an analytical chemical basis. In order to maintain this equipment with high service efficiency, there are some pre-requisite training needs which analytical maintenance personnel should acquire. CAE is committed to provide training course in these areas of specialized field.