Key words: intelligent differential pressure transmitter Differential Flowmeter range spare parts

Foreword
Microprocessor-based intelligent instrument to follow the scene at the scene of the bus and, equally, on-site application of intelligent instruments
Fieldbus for the development and application to provide a good foundation and make new problems for the experts. The scene at this stage
Intelligent instruments, just as described in the literature, because the protocol is not compatible, and the balance of conventional instruments 4-20 mA
Analog transmission of a point. Transition is a product of last resort. Also can not really adapt to the scene of the bus at the scene really smart instrumentation. It can not control system to reduce the initial installation costs. Can not give full play to its own function of the superior and more intelligent instrument can not be achieved at the interface between the exchange of information and operation.
However. Smart, after all, represents a new transmitter - the rise of the transmitter, it adopted many of today's high-tech.
Sensing technology, digital processing technology, microelectronics, and is often compared to the transmitter, with high precision, good stability, high reliability,
Wide range, range, and other than the specific. More advantage is that it achieved a number of communications. Through communication with the same
The agreement DCS system or communications controller at the scene of the smart transmitter make changes to the various parameters, settings, remote debugging
, human-computer dialogue. On-line monitoring of data. And all the smart instrumentation, smart transmitter also has a sound self-diagnosis function.
It can be said that the current transmitter is a smart alternative past, the scene on behalf of the future development of a new instrument transmitter.
2 intelligent application of differential pressure transmitter
Following on the practical application of the smart transmitter example, to play their various characteristics, process control solution measured King in the various questions: What should be pointed out that the market there are various types of smart transmitter. Intrinsic feature Different characteristics, the article cited by the individual examples are not necessarily of a general. Readers called Kam.
2.1 verify the actual original design Pressure
I plant copper caustic washing Section renewable positions. There is a differential pressure flowmeter for measuring air flow. For the regeneration of the air after the copper scrap copper than the regulation. The flowmeter design differential value of 10 KPa. But has been unable to operate normally. Site operators can only be judged by virtue of experience, control air traffic, to the process to operate with arbitrariness, blindness; door when. Excessive air in the system will increase the oxygen content and the threat of system security. Taking into account the air flow of small, small pipe technology, and original design parameters in the corresponding arts bias exists, so that verification of the original design is not very meaningful differential value.
Pressure in applications after the transmitter. Differential pressure transmitter with the smart use of input differential value of the function. Units from the provisions of the series of selected, the actual value differential design verification become very convenient, in coordination with staff positions, the actual measurement of the differential value of the work flow meter and the largest differential value. Surprisingly, the biggest differential value as high as 100 KPa. Is the original design value of 10 times, no wonder the original Differential Flowmeter not functioning properly. This differential value, with smart terminal to amend the transmitter on the limits of measurement, and the air traffic measurement automatically solved history can not solve, the problem has long been troubled.
In Differential Flowmeter applications, especially in low flow rate, measured on the pipeline, there may be the [Arts and a detailed parameters and the actual situation
there are serious deviations, and other family issues. Juice Pressure from the original value of a serious error, Lead to abnormal flow meter package. At this point, the smart use of differential pressure transmitter can play the role of simple things, use it directly before and after the actual measurement of the pressure to cut expenditure, which amended the original design values so that the difficult problems solved.

2.2 simplify the system of links
Intelligent Pressure transmitter only a simple set and access to the square root of the input signal differential between the output signal, thus free from the use of the prescribing Differential Flowmeter links. Simplify the measurement, control system components. Benefits is self-evident. At the same time. Prescribing small signal after the removal of another unique feature. There are two ways with small signal. One common prescription - kind, with the output signal is less than a complete resection points. As shown in Figure l.
Called "zero-removal method": The second is less than the output signals with points. Differential input and output signals into a linear relationship shown in Figure 2, called "linear manner with . " Resection of the way with two points in the 0% -20% between the continuous-tuning. Comparative figures 1 and 2 know. Linear manner with the minimum flow measurements, the benefit of the operation at the scene.
2.3 meters to reduce the number of spare parts
Nitrogen in enterprises, the main line of ammonia converter imports of hydrogen fluoride gas mixture flow measurements are large and small flow measurement of the flow measurement said.
Large flow for the reactor when normal production. Flows for the small reactor catalyst updated temperature reduction stage.
With conventional differential pressure transmitter to achieve when. The temperature reduction stage, to be installed on small range differential pressure transmitter (Our real value differential to 16 KPa, a furnace heated up when the security levels (that is, small traffic) control of measurement in temperature reduction phase after the reactor input Normal production. Also to be re-installed National Cheng Kung University range differential pressure transmitter (the actual value differential for 254 KPa). Differential pressure transmitter is usually routine. Do not have such a large range than. The need for full production, the flow of Measuring actually equipped with two differential pressure transmitter.
Intelligent use of differential pressure transmitter range than large. And have since set up, since the ability to check. Carried out by its main line of flow measurement.
Only through smart terminal in the control room to carry out small scale and large-value differential pressure differential value of the revised completion of the same purpose. To avoid the dismantling of conventional differential pressure transmitter calibration. Reduce the maintenance of instruments, to reduce the number of spare parts table.
The range of conventional differential pressure transmitter Yu than not. As familiar with the 1151 differential pressure transmitter. Range than is 6:1,
while the smart transmitter range can be achieved than at least 30 1. Generally up to 50:1. It is obvious. If you use smart transmitter as conventional 4-20 mA output transmitter of spare parts, spare instrumentation can greatly reduce the size and number.
2.4 for various parameters of the scene show
Instrumentation for simple settings, you can make intelligent transmitter LCD module containing a variety of data show. For example,
Pressure for the delivery. LCD can directly input and the corresponding pressure on the unit,
sent by the differential that allows LCD unit set the direction of traffic engineering and other values. In some cases can be omitted instructions at the scene first instrument, such as pressure gauges, and so on
without affecting the flow meter rotor at the scene of surveillance and operation. LCD display modules are compulsory self-diagnosis display, once measured parameters beyond the range or the transmitter itself fault, LCD will display an error code to replace the original set of parameters, to timely troubleshooting. If smart terminal, from the transmitter in the process of reading out more information.
3 technical issues to be improved
In use also found. Intelligent Transmitter still needed improvement of technical problems.
(1) how to achieve the transmitter of encryption to ensure that all data set the authority.
(2) how to reduce the transmitter in the communication, power supply requirements. Commissioning the scene to facilitate and safeguard.
(3) how to detect the transmitter of other information, such as temperature, the process of media pressure, differential pressure values, can be displayed on the smart terminal separated from the content. Amounted to a form more use.
(4) communications breakthrough agreement on how fragmented the situation and realize the standardization of communications, and open.
4 Conclusion
Although the price slightly higher than the smart transmitter conventional analog transmitter, but its cost performance of conventional instruments can not
And. Only a few cases of the above sum up the characteristics of the smart transmitter, there are other advantages but not limited to the length of itemized.
In short, even without the corresponding DCS system with matching, a reasonable choice intelligent transmitter, and there is no Dacaixiaoyong problems,
Automatic Control staff can help increase production efficiency and reduce the workload instrument to reduce instrumentation spare parts and broaden the work of thinking,
Provide new ways to solve the problem, new ideas and ultimately improve the production process automation level.
Is called "smart differential pressure transmitter of the initial application." Mainly due to the smart transmitter will not truly
The digital communications functions combined with the DCS system, fully reflects its comprehensive advantages. Used only as a conventional transmitter for
Generation, use some of its characteristics to solve problems in practical work. Aside intelligent instruments as the scene of the initial experience Dedication to peer.