Application of intelligent valve positioner in engineering practice Application of intelligent electric valve positioner in practice

Application of intelligent valve positioner in engineering practice Application of intelligent electric valve positioner in practice

Abstract: Control in the control valve, control valve in the valve positioner. The choice of valve positioner will directly affect the overall performance and quality of regulating valve and control system. Select intelligent valve positioner, improve the overall performance of the regulating valve, to achieve the overall improvement of control performance.
Key words: intelligent valve positioner engineering LCD fault diagnosis In petrochemical engineering design and engineering practice, we will choose a variety of systems and more kinds of detection and control instruments. Why is that? Because we want to achieve the control of the process, to achieve our required control effect. The realization of the control system includes three parts: detection, controller and regulating unit. Among them, the key to the application of the control unit is the control valve. The valve positioner is one of the most important accessories of the valve, it can be said that the valve positioner is the brain and soul of the valve.
With the practice of engineering design and international standards, we feel that the common valve positioner is more and more difficult to meet the requirements of engineering design and practice. Especially in advanced control systems and optimization control schemes emerge in endlessly, intelligent design has become a general requirement. From the realization of the overall performance and economic benefits of the control system is larger than the base point, we more and more choose intelligent valve positioner.
As an engineering designer, the author has used the intelligent valve positioner produced by major instrument manufacturers at home and abroad. Combined with their own experience in engineering design and service, Siemens intelligent valve positioner as the main, considering other manufacturers, talk about the application of intelligent valve positioner in engineering practice.
The advantages of an intelligent valve positioner
1) improve the performance of the regulating valve and control system
The control precision of the intelligent valve positioner is very high, which can realize the precise control of the regulating valve, so as to improve the control level of the system. In addition, intelligent valve positors make it easy to set the valve characteristic curve, such as equal percentage characteristics, Siemens PS2 series offers 1:25,1:33,1:50 features, ABB TZ>2) save gas, energy and cost
We require continuously in line with the international, but in the world *** big petrochemical company’s cost is controlled very well and our country after so many years of effort but still has very big gap with the world advanced level? From a small point of view, we did not calculate the economic accounts when we did the project. Take the instrument wind as an example, the production of a vertical instrument wind the minimum energy consumption is 1.6MJ, one degree of electricity is 3.6MJ, industrial electricity is generally 1 yuan/degree, not considering the water removal, oil removal, dust removal, equipment investment and instrument workers wage costs, the average production of a vertical instrument wind is 0.44 yuan. Domestic locator and some intelligent locator manufacturers, due to technical reasons, the gas consumption per hour is very large, generally speaking, the steady-state gas consumption of these products in 350 liters/hour. Save gas for Siemens PS2(steady state gas consumption 36 l/h) and ABB TZ>3), keep the public network pressure stable
For large petrochemical enterprises, due to a lot of gas points, large gas consumption, to the end of the device or far away from the air compressor station, instrument wind pressure is very low, sometimes can not even promote the normal work of the regulating valve, can not meet the normal safety production of the device. If the intelligent valve positioner with low gas consumption is adopted, the total gas consumption will be reduced due to the minimal gas consumption, so as to maintain the stability of the instrument wind public network pressure and ensure the safe and reliable production of the device.
4) The initialization process is very simple
For most smart valve positioners, the initialization process is basically very simple. In the case of the Siemens PS2, the initialization process can be automatically completed by pressing four buttons and setting a few simple parameters. More convenient is that the set parameters uploaded to the computer, can be copied to the same condition of the locator by downloading batch, ** * saving manpower and time, especially in the new device start or overhaul.
5) Intelligent communication mode
The most obvious feature of the intelligent valve positioner is intelligent communication. For our process industry, the most commonly used is HART communication, or PA fieldbus, or FF fieldbus. But not all intelligent valve positioners support the above communication methods. Siemens PS2 intelligent valve positioner, which is widely used in petrochemical enterprises, not only supports the above communication protocol, but also can carry out AMS communication. In the actual engineering application, if the HART communication (** commonly used, other communication methods can also be), through the corresponding software and hardware, you can save all the parameter information of the factory intelligent valve positioner to the computer, which is the ordinary handheld terminal can not achieve. When it is necessary to maintain or replace the intelligent valve positioner, the instrument parameters can be easily retrieved from the information base and quickly downloaded to the valve positioner, which greatly saves labor time and cost. In addition, it is no longer difficult to save a large number of data.
6) Binary input ** lock switch valve
For the intelligent valve positioner, most of them have self-protection interlocking function. The ABB VALVE LOCATOR CAN SELF-LOCK IN THE EVENT OF a POWER OUTAGE, AND THE Siemens PS2 CAN ALSO SELF-LOCK OR SWITCH THE VALVE ON AND OFF WHEN THE SIGNAL IS DISCONNECTED. In addition to these functions, these locators also receive input from external linkage signals. While these chain reactions are not on the order of milliseconds, for many process industries, second chains are sufficient. For example, the heating furnace fuel oil valve chain. At the same time, the safety level of the high requirements of the millisecond level linkage, in the design requirements to be set separately, not allowed to be put together with the control loop, so the requirement of intelligent valve positioner interlocking to reach the millisecond level is not practical significance.
7) Convenient and quick setting of division adjustment
According to the actual needs, engineering design needs to use an input signal to achieve control of two or more regulating valves, which requires the valve positioner only to a certain range of the input signal response. Taking Siemens PS2 as an example, it is convenient to set the starting point and ending point of the process adjustment by software or manual.
8) Rich fault diagnosis function
Fault diagnosis function is a very important function of intelligent valve positioner. In the actual construction or commissioning process, we will encounter a variety of problems. How to judge and solve these problems correctly is very important to the normal and safe production of the device. For the intelligent locator, the diagnosis of valve leakage, valve packing, valve wear, etc., is the function provided by most intelligent locator manufacturers. But there are also some manufacturers provide little or no functions, so be sure to read the sample and consult the manufacturer when selecting the type.
Two intelligent valve positioner selection
In the engineering design, we should carefully choose the appropriate intelligent valve positioner, specifically pay attention to the following points:
1) It is required to meet the requirements of on-site working conditions and realize intelligence
We choose intelligent valve positioner, is to obtain its intelligent function and improve the overall control performance. Therefore, under the condition of satisfying the field working conditions, intelligence is an important index for us. Intelligence includes its communication function, online or offline fault diagnosis function, etc.
2) The on-site operation is required to be convenient
For some intelligent valve positioner products, because the setting is more complex, the effect of the product in actual use is affected. Therefore, we give priority to products that are easy to operate.
3) High cost performance, energy consumption and cost saving
In addition to the initial investment of the instrument, we also consider its operation cost. From the time period of 3~5 years, which kind of product comprehensive performance is high, we choose which kind of product.
4) Require on-site display
For some intelligent valve positioner products, because there is no on-site liquid crystal display, so in the field adjustment must be adjusted by hand operator. This adds to the cost. In addition, for LCD liquid crystal display, attention should be paid to its display effect at very low ambient temperature.
5) It is required to ensure the normal operation of remote installation under certain circumstances
As more and more large petrochemical enterprises now use the combined central control room, the distance from the control room to the on-site intelligent valve positioner may be very far. The problem of cable voltage drop must be considered, otherwise the intelligent valve positioner cannot work normally.
Three intelligent valve positioner in engineering practice application example
In the process of engineering construction and device running, due to the design, construction and maintenance of various reasons, the regulator will produce a variety of failures. For some problems, we can solve by intelligent valve positioner.