Smart Pressure Transmitter
Published on：2015-3-4 10:38:39 Hits：
Microprocessor-based smart field instruments to follow the fieldbus produced, and similarly, the application of smart field instruments
Also provides for the development and application of fieldbus a good foundation and raise new questions for the experts. Stage scene
Intelligent instruments, just as described in the literature, due to incompatible communications protocols, as well as taking into account the conventional instruments 4-20mA
Holding point analog signal transmission. Is a last resort for a transitional product. Can not really adapt fieldbus really intelligent field instruments. It does not reduce the initial installation cost control system. Can not fully play its itself has superior features, but can not achieve the mutual exchange of information and operations between smart field instruments.
However. After all, represents a new smart transmitter - Rise generation transmitter, which uses a lot of today's high-tech. As
Sensor technology, microelectronics digital processing technology, compared with the constant current transmitter, with high accuracy, good stability, high reliability,
Wide measuring range, turndown ratio and large specific. Advantage is that it implements the digital communication. By having the same communication
Agreement DCS system or field communication controller can be of various parameters changed smart transmitter, set and achieve far
Debugging process, human-computer dialogue. Online monitoring of various data. Like all smart instrumentation, smart transmitter also has a perfect
Self-diagnostic function. It can be said that the current smart transmitter is an alternative to the past, the new transmitter site on behalf of the future instrument development.
Application 2 Smart Pressure Transmitter
The following examples on the practical application of smart transmitters, and play its various features, the settlement process control measurement King appeared in a variety of problems: the need to point out that there are various types of smart transmitters on the market. Inherent feature will feature different, so individual cases cited herein do not necessarily have a common nature. Readers called Kam.
2.1 Differential actual verification of the original design
I plant copper caustic regeneration section positions. There is a differential pressure flowmeter for measuring air flow. Liquid air for regeneration after scrap copper ratio adjustment. The differential pressure flowmeter is designed 10KPa. But has been unable to operate normally. Site operators only by virtue of experience to judge, control the air flow to the craft to operate with arbitrariness, blindness; the door. Excessive amount of air causes the system to increase the oxygen content and threat to system security. Considering that the air flow is small, small pipes, and original design appropriate process parameters bias, so that the original design theory verification differential value becomes meaningless.
After the application of intelligent pressure transmitter. Using intelligent pressure transmitter has a function to display the input differential values. Units can be selected from a series of provisions, the actual differential pressure proven design has become very convenient, in cooperation with staff positions, the actual measured value of the differential pressure flowmeter work with maximum differential pressure values. Surprisingly, the maximum differential pressure values as high as 100KPa. 10 times the value of the original design, no wonder the original differential pressure flowmeter not run properly. Click differential value, with intelligent terminal modifications on the measuring transducer limits, to achieve the automatic measurement of air flow. Historically solve unsolved problems has long problem.
In the differential pressure flowmeter applications. Particularly in low flow, small pipe, there may be engineering [a detailed process parameters or
There is a serious error and other problems with the actual situation. Rise to the original value of the differential pressure based sauce serious error, causing the entire flowmeter exception. At this point, citing Smart Pressure Transmitter can play the role of simplify, use it to measure the actual pressure orifice directly before and after the original design values corrected accordingly, so that the difficult problem solved.
2.2 simplified system consisting link
Smart Pressure Transmitter only be obtained through a simple set square root of the input differential signal output signal, which can be exempted from the use of prescribing aspects of differential pressure flowmeter. Simplifies the measurement, control structure of the system. Benefits are self-evident. At the same time. After prescribing low-cut also has a unique feature. There are two low-cut way. One of the common prescription is - like, when the output signal is less than complete resection resection points. Shown in Figure l. Called "zero-removal mode": the other is in the output signal is less than the cut point. The output signal to the input differential pressure signal into a linear relationship. Shown in Figure 2, called "linear resection." Two resection cut point between 0% -20% continuously adjustable. Comparing Figure 1
And Figure 2 shows. Linear resection in the lower flow rate measurement, benefit-site operations.
2.3 meter to reduce the number of spare parts
Nitrogen businesses, ammonia synthesis reactor main import of hydrogen, fluorine mixed gas flow measuring large flow measurement and flow measurement of small
Said. Large flow of normal production for the synthesis of the tower. Catalyst for the synthesis of small flow tower updated TPR stage. Conventional
Achieved when the differential pressure transmitter. In TPR stage, to be mounted on a small-scale differential pressure transmitter (Our actual differential value 16KPa, were safe when heating furnace gas (ie, low flow) measurement and control; at the end of the stage after TPR, synthetic tower investment Normal production. and the need to re-dress into large-scale differential pressure transmitter (actual differential pressure is 254KPa). Typically conventional differential pressure transmitters. does not have such a large range of ratios. for full production needs, the flow actually measuring the differential pressure transmitter is equipped with two.
Using intelligent pressure transmitter range ratio. And a self-setting, self-checking capabilities. Conducted with its mainline flow measurement.
Only by a small-scale intelligent terminal modifications and large range differential pressure differential pressure values in the control room, to accomplish the same purpose. Avoid the conventional differential pressure transmitter calibration disassembly. Reduce instrument maintenance work, reducing the number of spare tables.
Conventional differential pressure transmitter range less than Yu. Like the familiar 1151 differential pressure transmitters. Turndown ratio of 6: 1, and the wisdom
The transmitter can range than can be achieved at least 30; 1. Generally up to 50: 1. Obvious. If you use smart transmitters as conventional 4-20mA output transmitter spare, can greatly reduce the size and number of spare instruments.
2.4 to facilitate various parameters on-site display
Instrument for simple setup, you can make smart transmitter built-LCD module to display a variety of data. As
Pressure by the transmitter. LCD display allows direct input pressure and the corresponding units, differential pressure transmitters subject, to make the LCD indicating unit
Custom traffic engineering values, etc. In some cases you can omit the scene once indicating instrument, such as pressure gauges, flowmeters, etc.
Without affecting the on-site monitoring and operation. LCD display module with mandatory self-diagnosis display function, once measured parameter out of range or transmitter failure itself, LCD will display an error code to replace the original set parameters showed beneficial timely troubleshooting. If through the intelligent terminal, you can read more process information from the transmitter.
3 technical problem to be improved
Also found in use. Smart Transmitter there still need to improve the technical problems.
(1) how to implement the encryption on the transmitter, various setting data to ensure authority.
(2) how to reduce demands on the power supply when the transmitter during communication. Convenient on-site commissioning and maintenance.
Content (3) how to detect other information transmitters, such as ambient temperature, process medium static pressure, differential pressure, etc. can be displayed on a smart terminal separated. To achieve a multi-purpose table.
(4) how to break the fragmented situation on the communication protocol to standardize communications, open technology.
Although the price is slightly higher than the conventional Smart Transmitter analog transmitter, but they are not conventional instruments can cost performance
And. Only a few cases summarized above smart transmitter characteristics, there are other advantages of the limited space and can not enumerate.
In short, even if there is no corresponding ancillary DCS system, a reasonable choice of smart transmitters, there is no overkill problem,
Controls who can help increase productivity, reduce the workload of the instrument, the instrument to reduce spare parts, to broaden the work of thinking,
New methods, new ideas to solve problems, and ultimately improve the level of automation of the production process.
It is called "the primary application of smart differential pressure transmitter." The main reason is not the true meaning of the Smart Transmitter
Digital communication functions and DCS systems combine to fully reflect its comprehensive advantages. Only as a conventional transmitter for
Generation, the use of some of its features to solve practical problems. As the field of smart metering applications tentatively primary experience
Dedication to peers.
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