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Published on:2015-11-10 9:42:57 Hits:

Keywords: intelligent differential pressure transmitter differential pressure flowmeter measurement range of spare

Foreword

Microprocessor-based smart field instruments to follow 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 expert studies. Present site

Intelligent instruments, just as described in the literature, due to incompatible communications protocols, as well as taking into account conventional 4-20mA instrumentation

Hold point analog signal transmission. It is a last resort transitional product. We can not really adapt fieldbus really intelligent field instruments. It does not reduce the initial installation cost control system. We can not give full play to its own has superior features, but can not achieve the mutual exchange of information and operations between smart field instruments.

However. After all, it represents a new smart transmitter - rise on behalf of the transmitter, which uses a lot of high-tech today. Such as 

Sensor technology, microelectronics digital processing technology, now often compared to the transmitter, with high accuracy, good stability, high reliability,

Wide measuring range, turndown ratio and large specific. Advantage is that it implements the digital communication capabilities. By having the same communication

Agreement DCS systems or field communication controller can be of various parameters smart transmitter is changed, set and achieve far

Cheng debugging, human-computer dialogue. Online monitoring various data. Like all smart instrumentation, smart transmitters also have a sound

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 of 2 Smart Pressure Transmitter

The following examples concerning the practical application of smart transmitters, to play its various features, the settlement process control measure in view emerging issues: the need to point out that there are various types of smart transmitters on the market. Inherent functionality will feature different, so individual cases cited herein do not necessarily have common properties. Readers called Kam.

2.1 The actual verification of the original design Pressure

I plant copper caustic regeneration section positions. There is a differential pressure type flow meter for measuring air flow. Liquid air for regeneration after copper copper ratio adjustment. The design of the differential pressure flowmeter is 10KPa. But it has been unable to operate normally. Site operators only by virtue of experience to judge, control the air flow to the process operation partner to 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 theoretical verification of the original design differential value becomes meaningless.

After the application of intelligent pressure transmitter. Using intelligent differential pressure transmitter has a function to display the input differential values. Units can be selected from a predetermined range, the actual design verification differential value becomes 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 value as high as 100KPa. It is 10 times the original design value, no wonder the original differential pressure flowmeter can not operate normally. Click differential value, smart terminal modifications on measurement transducer limits, to achieve the automatic measurement of air flow. Historically resolved not resolved, it has long been plagued by problems.

In the differential pressure type flow meter applications. Especially in the measurement of small flow, a small pipe, there may be work [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 juice serious error, leading the entire flowmeter exception. In this case, the reference smart differential pressure transmitter can serve to simplify the role actually use it directly measuring the pressure before and after the orifice, thus correcting the original design value, 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 part of the use of prescribing differential pressure flowmeter. Simplify measurement, control configuration of the system. Benefits are self-evident. Simultaneously. After prescribing low-cut but also has unique. There are two low-cut way. One with ordinary prescription device - like, when the output signal is less than the cut point completely removed. Shown in Figure l. Called "zero cut way": The second is the output signal is less than the cut point. Differential output signal with the input signal into a linear relationship. Shown in Figure 2, called "linear resection." Both resection cut point between 0% -20% continuously adjustable. Comparing Figure 1

And Figure 2 shows. Linear resection measurement when the lower limit of the flow rate, good for live action.

Reduce the number of spare parts 2.3 meter

Nitrogen enterprises, ammonia synthesis tower main import hydrogen, fluorine mixed gas flow measuring a large flow measurement and flow measurement of small

Say. Great flow for the synthesis column normal production. Low flow for the synthesis of Catalyst updated TPR stage. Conventional

When the differential pressure transmitter to achieve. In TPR stage, to be mounted on a small-scale differential pressure transmitter (Our actual differential value 16KPa, carried out when electric heating safe air (ie, small flow rate) measurement and control; after TPR end phase synthesis column input normal production. and the need to re-dress larger than the range differential pressure transmitter (actual differential pressure is 254KPa). Typically conventional differential pressure transmitter. does not have such a large range than. is full production needs, the flow in fact it equipped with two measuring differential pressure transmitter.

Using intelligent differential pressure transmitter range ratio. And a self-setting, self-checking capabilities. Performed with its mainline flow measurement.

Only through the intelligent terminal to modify small-scale and large range differential pressure differential pressure in the control room, to accomplish the same purpose. Avoid the conventional differential pressure transmitter disassembly check. Reduce instrument maintenance work, reducing the number of spare parts table.

Conventional differential pressure transmitter range is not more than Yu. Like the familiar 1151 differential pressure transmitter. Turndown ratio of 6: 1, and wisdom

Transmitter turndown ratio can reach at least 30; 1. Generally up to 50: 1. Obvious. If you use smart transmitter 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

Simple instrument set, you can make intelligent transmitter built-LCD module to display a variety of data. Such as 

Pressure by the transmitter. LCD display allows direct input pressure and the corresponding units, differential pressure transmitter that enables LCD indicates Unit

Custom traffic engineering values, etc. In some cases you can omit the scene once indicating instrument, such as pressure gauges, rotameters, etc.

Without affecting the field of monitoring and operation. LCD display module has forced self-diagnosis display function, once the measured parameter is out of range or the transmitter itself fault, LCD will display an error code to replace the original set parameters of the display, which will help in time 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 exist technical problems still need to improve.

(1) How to achieve the transmitter encryption to ensure the authority of the various setting data.

(2) how to reduce demands on the power supply when the transmitter during communication. Easy on-site commissioning and maintenance.

Contents (3) How to measure other information transmitters, such as ambient temperature, process medium static pressure, differential pressure, etc. can be displayed on the smart terminal separated. To achieve a multi-purpose table.

(4) how to break the fragmented situation on the communication protocol, standardized communications, open technology.

4 Conclusion

Although the price is slightly higher than the conventional Smart Transmitter analog transmitter, but its cost performance but not with conventional instruments can

And. Only a few cases above summarizes the 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 systems, smart transmitters reasonable choice, there is no question of overkill,

Automation can help staff increase productivity, reduce workload instruments, reducing meter spare parts, 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 intelligent differential pressure transmitter." The main reason is not the true meaning of the Smart Transmitter

Digital communication and DCS systems combine fully reflect its comprehensive advantages. Only as an alternative to conventional transmitters

On behalf of, the use of some of its characteristics to solve real work problems. As the field of smart metering applications tentatively primary experience

Dedication to peers.


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