Sequencer for process instruments

Description

JWT Sequencers- For Process Analyzers The Problem: you have some expensive process analyzers for *****, Sodium, Silica, Phosphate, or other process chemistry. They are expensive to buy, and expensive to operate. How can you get the most value for your money? The Solution: A JWT sequencer can turn your analyzer into a multi-stream instrument. Just one process instrument can be used for multiple sample streams (the number is theoretically unlimited) and will operate completely unattended. Our sequencer includes a PLC mounted in an enclosure, an operator station for control, and a solenoid valve manifold for switching the sample streams to the instrument. The sequencer includes a complex computer program that controls all the functions necessary to provided accurate analysis for each sample, and to sequence streams as fast as possible. Our experience works for you. We have years of experience in this field, and have in-depth experience with most process analyzers. Anyone can make a sequencer. But few companies can make a sequencer that include the features of our sequencer, features that are designed to provide you with accurate chemistry control. The purpose of a chemical analyzer is to provide accurate readings, and to allow you to control your chemistry. For power plants, especially the latest generation, chemistry is of critical importance. Poor control increases the potential for corrosion and stress-corrosion cracking, and may result in expensive replacement of condenser tubes, turbine blades, and process piping. A poorly designed sequencer can affect the chemistry readings, and in the long run can result in disaster for the plant. Don’t be fooled by cheap imitations. A JWT sequencer is the best that you can buy, and we back them up with a guarantee: our sequencers will NEVER be proven to affect the chemistry readings when properly set up and installed, and we will gladly refund your money if you can prove otherwise. Considerations when sequencing: When sequencing, there are many things that you need to take into account, such as….. 1. How the materials of construction affect the chemistry readings. 2. Dead spaces or crevices allow contaminants to hide out and affect the next reading. 3. Sequencing between samples of largely differing concentration can affect the subsequent reading, particularly when going from a sample of high concentration to one of low concentration. 4. The sample velocity is critical. Low flow can result in ions being absorbed onto the tubes and valves (thus contaminating the lines) which can affect the next reading. It’s important to keep the sample flow from one stream to the next as close to the same as possible, to reduce the potential for this problem. 5. Plastics are notorious for permeability to gasses. When measuring ***** (dissolved oxygen) the materials used must be impermeable to gasses to eliminate affecting the readings. (A typical ***** measurement in a power plant is in the range of ***0 ppb. The concentration in air is over 8 ppm. Even a slight permeability can ruin your ***** readings. 6. Solenoid valves must have a small internal dead space, and the common ports must be as small as possible. 7. Solenoid valve manifolds that flow in one direction can result in a huge dead space, and can make your chemistry readings bad by contaminating the sample. 8. The software must be easy to use, and simple to understand. Otherwise, the operators may adjust the sequencer in a way that results in errors. 9. Preferably, the sequencer will allow the plant control system to interact with the sequencer to provide remote control and collection of data (readings). Features of JWT Sequencers The features are almost too many to mention, but can be roughly grouped by our “standard” sequencers, and our “custom” sequencers. The standard sequencers are designed for one analyzer, and come prepackaged and include a set of features for most sequencing applications. Our custom sequencers can include any options you prefer, limited only by your imagination and budget, and come fully programmed and tested. Standard Sequencers Can turn the sequencer OFF, or PAUSE the sequencer at any stream. In PAUSE, you can advance to any sample. Includes 1 dry contact output per stream, or one ***0 mA output per stream. Separate models are used for continuous analyzers or for batch type analyzers. The batch type analyzers must include an “end-of-cycle” contact closure to indicate when the current analysis cycle is complete. Continuous analyzer models include an adjustable “delay time”. This is the length of time it takes the analyzer to settle out at the new reading after switching streams. Concentration adjustment feature allows automatic change in cycle times when switching between samples of greatly differing concentration. Analog output models provide “track and hold” for each sample stream. This makes the sequencer appear to the plant control system as one analyzer for each stream, and provides a continuous output. (The output is held at the last reading when on the other samples.) Custom Sequencers Custom sequencers can perform the functions of the standard sequencers, but can also include many additional features. Multiple analyzers can be sequenced in one sequencer. We recommend a larger operator station (a color touch-sensitive display is preferred) to improve the ease of control with multiple analyzers. If you have a large control panel, we can include analog inputs for all the other analyzers. These can be displayed on the operator station, or transmitted to the plant control system via Ethernet, Modbus, or other protocol. Replacing analog wiring with a single communications cable results in a savings that will easily offset the cost of the sequencer. Alarm displays to alarm chemistry readings, or other system alarms. PID control for your chemical feed pumps. We’ve done all of the above, and more. Please contact us for additional information.