Introduction

RRB Sugar Mills Ltd. is one of India’s largest sugar producers,with a cane-crushing capacity of 400 Tons of Cane per Day(TCD). While most industries rely on external power sources tofuel their operation, sugar manufacturers can produce their ownpower in a process called cogeneration. As part of the process ofproducing sugar from sugar cane, by-products such as bagasse—aleft-over fiber from the crushing and extraction process—can beemployed as an eco-friendly fuel for power cogeneration. Thebagasse can be incinerated to fuel a boiler furnace, which can beused to produce electricity. The power, produced by the furnacecan be used in the production of more sugar cane—a net positiveenergy gain.

Historically, sugar mills in India were permitted to produce onlythe energy they needed for their own operations. Most Indiansugar companies therefore adopted the practice of installinginexpensive boilers and turbines, which also happen to benotoriously inefficient. They typically would operate only duringthe sugar season. After all, why invest money in an expensive,efficient system, when there’s very little opportunity for a returnon that investment?

• Using InduSoftWeb Studio,

parameters at every step in

the process are monitored

for quality assurance.

• RRB’s engineers and

operators can easily make

adjustments to the system

themselves; there is little

need for field support.

•With InduSoftWeb Studio,

RRB Sugar Mills can easily

evaluate system efficiency,

reducing the per-unit

generation cost.

India is discovering that with the high price of crude oil, cane sugar is rapidly becoming a valuablecommodity in the form of energy-rich ethanol.

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In the mid-1990s, though, the Indian ministry of power beganpermitting companies to generate surplus energy. The energycould then be exported to the state electricity board or to othermanufacturers, which in turn subsidizes production costs,promotes competition, and makes electricity more plentiful foreveryone.

When exportation of energy was permitted, many plants,including RRB Sugar Mills, began looking for ways to increasethe efficiency of their power plants. At its Wategaon, India,facility, RRB installed backpressure turbo-alternators with twohigh-pressure boilers, a turbine generator and a backpressureturbine generator.

This required a new control system, and InduSoft Web Studiowas chosen to develop an HMI/SCADA system that wouldensure an efficient plant. Although the system was initiallyinstalled only to control the boilers, it worked so well that RRBexpanded it to also control the entire sugar-making andwastewater processes.

The Challenge

Project managers at RRB knew they needed a Systems Integratorto develop and implement the automation and control system,and they turned to Control and Solutions India Limited (CSIL).CSIL was chosen because they specialize in automation andcontrol systems for the Process Industries, Building Automation,and Substation Automation. After reviewing the existingcogeneration system, CSIL provided RRB several options for acentralized system that would meet their requirements.Ultimately, RRB selected an InduSoft Web Studio-basedHMI/SCADA System with Honeywell PID loop controllers.

The boiler control has many useful features that have made theprocess much more manageable. For example, it reads boilerprocess parameters from primary sensors and secondaryinstruments, which helps RRB control critical points in theprocess. The system also controls threshold deviations andactivates alarms if thresholds are breached. History data logging isbuilt into the system and a browsing feature provides access tothe logs for a complete history of the operation.

Designed for Microsoft Windows environments, InduSoft WebStudio uses open technologies to connect to monitoring andcontrol hardware and third-party software applications.Honeywell’s PID controllers are based on open technology andwere easily networked to the InduSoft-based system.

Top Left: The main control screen is simple and intuitive. Theapplication learning curve for operators and engineers is measuredin hours rather than days or weeks.

Bottom Left: With a single glance an operator can assess the entireboiler system—a vital safety consideration.

To monitor the boiler temperature, temperature scanners wereeasily integrated into the InduSoft system through a Modbuscommunication driver. The application collects temperature datafrom these scanners, displays temperature values on colorgraphic screens, and logs the data where it can be used togenerate graphs.

CSIL and RRB engineers developed the HMI/SCADAapplications, which included control algorithms, alarm andreporting systems, and data logging functions. This full-featured,performance management system was developed andimplemented using InduSoft Web Studio’s menu-based RapidApplication Configuration Environment (RACE). TheInduSoft-based system presents real-time data from the boilersand turbines to the analyzing logic, and then downloadsappropriate set-point changes to the PID controllers.

Automating Sugar Production

After the power generation control system was updated, CSILand RRB turned their attention to automating the sugarproduction process with InduSoft Web Studio. In the sugarindustry, capacity utilization is conceptually different than mostindustries. It depends on three crucial factors:• The TCD rate• The recovery rate, which primarily depends on the quality

of the cane• The length of the crushing season.

The production tonnage is a function of the plant capability andvariables governed by the other two factors (cane quality andcrushing season), both of which are dependent on plant location.The quality of the cane is outside factory control, because cane isnot usually transported great distances. Production plants musttherefore rely on local cane crops, the quality of which dependson climate and weather patterns as well as soil and geography.

Likewise, the length of the crushing season also depends on localclimate. Southern India, which has a tropical climate, has thelongest crushing season and plants in that region tend to producethe greatest tonnage.

During the refining process the natural sugar stored in the canestalk is separated from the rest of the plant material as it movesthrough the sequential production phases:1. The cane is pressed to extract the juice.2. The juice is boiled until it begins to thicken and the sugar

begins to crystallize.3. The crystals are moved to a centrifuge to remove the syrup,

producing raw sugar.4. The raw sugar is then sent to a refinery where it is washed and

filtered to remove remaining non-sugar ingredients and color.

The alarm history is available with the touch of a button, and as eachalarm is acknowledged the notification is changed from Red to Green.

Operators can monitor the syrup levels as they are pumped from the maintank through the staging pans, ensuring an even flow with no gaps.