Overview
Process industry is defined where chemical change takes place during the manufacturing process. Process industry consists of continuous and batch process segments. Key industry sectors that qualify as process industries include chemicals and petrochemicals, oil & gas, food & beverages, tobacco processing, coal, textile fabric processing, textile yarns, mineral and metal refining and extrusion, wood , minerals, pulp and paper, printing, publishing, pharmaceutical– bulk chemicals and formulation, water and wastewater, and other consumables.
Key Challenge
Methods of measurement for flow, pressure, level, and temperature have been around for a long time. This implies that sensors and transmitters have achieved a certain degree of penetration in almost every process industry, especially in industrialized regions such as North America and Western Europe. The challenge for the manufacturers is to achieve growth in mature markets. Process industry users are knowledgeable about the sensor technology and demand low-cost products. With limited technical innovation taking place in sensor technologies, product differentiation has become a critical challenge for the manufacturers. Refining the distribution strategies is one of the challenges that many manufacturers come across to achieve higher sales, while reducing sales overheads.
Technology and Communication Trends
Technological trends in the process industries sensors are witnessed in providing the most affordable, reliable, and safest way of communication from the field up to the system. Due to continuous process a lot of process data are generated which are used to monitor and control. To move the data to and fro, the most commonly used field buses in process industry are Foundation & Profibus PA at the systems level. At the device level below PLC level HART protocol is the most popular process.
Most process plants such as refineries, integrated steel plants, and petrochemical plants are generally spread to large physical area. There is a large installed base of legacy systems which are wired. While upgrading these legacy systems the wired sensors are replaced by wireless sensors to ensure failsafe connectivity and two way data movement. Process industries are also looking at fiber optics as a potential solution in the retrofit of major plant sites.
Integration of diagnostics with verification features has made the sensors smarter. These features are able to inform about the status of the instrument to the engineers. Adding a digital signal processor (DSP) capability is currently a common trend in the market, which results in faster detection of signals and diagnostics. Sensors are gradually becoming intelligent with predictive capability. The installation of intelligent sensors has enabled activation of real-time corrective in critical process applications.
Key Networks Protocols
Automation systems are complex as they are structured into many hierarchical levels with each level having communication which places different requirements on the communication network. The industrial network consists of functionality based levels starting from field level at the bottom of the hierarchy through control level to information level at the top. The field devices, sensors, and actuators communicate through buses. Actuators and sensors use buses to connect discrete devices with built in intelligence.
Buses are designed to compress large data/information into bits and bytes to ensure uninterrupted flow of information. The effort is to reduce cost per node and at the same time ensure quality communication. The fieldbus networks with truly distributed control and intelligent devices are most common combination. Networks that are commonly used on devicebus and fieldbus include Profibus-DP, Foundation Fieldbus, DeviceNet, LonWorks, SDS, CANOpen and Interbus-S. Among these fieldbuses networks Profibus is the most deployed in process industry for control applications. These include its versions DP, FMS, and PA. The buses are networked with a wire (one/two) of multi-point input sensors, intelligent devices, sub-networks such as AS-I, and operator interfaces and variety of different valves for diverse applications.
Changing Approach
The traditional 4-20 mA had been widely used. Now for a long time 4-20 mA with HART continued to be in demand in instruments as there exists a large installed base of legacy systems. Foundation Fieldbus and Profibus PA digital communication protocol have strongly been penetrating into process industry. Over the next 3-5 years usage of Profibus PA and Foundation Fieldbus is expected to grow in greenfield investments/projects, driven by the new trend of reading out additional/advanced information for diagnostics, and condition monitoring from the field devices, which is hard to achieve by the HART protocol. Wireless seems to be a new frontier but yet to come as real industrial mass application. The wireless technology today is still largely limited to monitoring applications only. With the advent of IOT platform sensor are likely to play larger role in data mining from field devices to enable real-time remote monitoring and control of process plants.
Key Advantages
(i) 4-20 mA HART
4-20 mA with HART is very close to conventional 4-20 mA, and the user does not have to understand the software in depth. It does not give any advanced information. Ease of use and cost effective installation are its major advantages. It does not require training to use.
(ii) FOUNDATION Fieldbus & Profibus PA
Both FOUNDATION Fieldbus & Profibus PA provide additional information such as diagnostics and condition monitoring. They reduce life-cycle cost of production line, and the total cost of ownership of the plant. They allow integration of plant assets on a single plant automation system on digital communication networks. Both allow for the reporting of self diagnostics, calibration, and environmental conditions of field instruments without disturbing the plant control. Usage of PROFIBUS and Fieldbus Foundation field instruments requires a lot more training. Software knowledge is necessary to be able to use Profibus and Foundation Fieldbus instruments
Conclusion
In the past, the usage of Profibus and FOUNDATION Fieldbus depended on the industry type. For instance, the chemical and the oil and gas industries were more inclined toward foundation fieldbus, whereas the water industry was more inclined toward Profibus. In the past, the usage of Profibus and FOUNDATION Fieldbus also varied by geographic regions. For instance, in Europe Profibus (a German standard driven mainly by Siemens) was preferred, and in America’s favored FOUNDATION Fieldbus (driven mainly by Emerson Process) was finding favor.
This scenario is now changing as market participants are witnessing the usage of both FOUNDATION Fieldbus and Profibus in all types of process plants across all regions. Wireless and Fieldbus technologies are expected to achieve growth from greenfield projects.
