Learn Industrial Control Systems – Part-1

Recipe based automatic batch weighing

– Design, System Integration, Component Specifications & application details.

What is Industrial Control Systems?

Industrial Control Systems is a tool through which plant operators monitor and control industrial processes. Some important industries which use Industrial Control Systems are Oil and Gas Industries, Nuclear Power Plants, Thermal Power Plants, Power transmission and Distribution companies, Manufacturing Industries, Chemicals & Pharmaceutical Plants, Breweries and other industries. Industrial Control systems includes Supervisory Control and Data Acquisition (SCADA), Distributed Control Systems (DCS), Programmable Logic Controllers (PLCs), Remote Terminal Units (RTUs), and any other type of technology specific to running an industrial operation.

This website will take you to a round trip to the electronics controls and automation systems in various important industries. The components, sensors, modules, actuators, robots, micro-controllers, Input / Output devices etc. will be analytically explained through blogs.

Let’s start with a simple recipe controlled fully automatic electronic hopper weighing system.

Before we step into more intricate industrial control systems, we will explore a simple industrial control system. This will enable your electronic control system fundamentals strong and you will easily understand more complex control systems discussed in other blogs. Don’t worry; you will find more complex systems in coming parts.

Look at the Fig-1 below.

electronics15.com_learn_hopper_weighing                                                 Fig – 1 – Recipe based Hopper Weighing

Fig-1 shows the schematic of a simple Automatic Industrial Control System. This is a “Recipe Controlled Fully Automatic Hopper Weighing System”.  The system has two hoppers – Main Hopper & Weigh Hopper. The main hopper is actually a storage hopper where process materials are stored. The manufacturing process requires materials in a pre-calculated weight as the process demands. The weigh hopper supplies the materials in pre-set quantities to a waiting trolley or a conveyor.

The main Hopper is fitted with two pneumatically controlled actuator Valves. One is called “Full Flow Valve” and the other one is “Dribble Flow Valve”. These valves are controlled by a “Recipe based Electronic Controller”. Recipe means how much materials can be withdrawn from main hopper to weigh hopper. This is pre-set through a keyboard provided at the controller.

When the “START” button is pressed, Full Flow gate is opened fully and the rate of flow is high. After a pre-determined weight, the Dribble Flow gate will control the flow accurately so that weigh hopper receives the exact pre-set quantity of materials during each cycle.

The Full Flow and Dribble flow valves are controlled with respect to the weight of the materials that the weigh hopper receives. The Weigh hopper is equipped with Three Load Cells placed at 120 degrees to weigh the materials that are transferred to the weigh hopper.  The success of a Recipe Controlled Fully Automatic Hopper Weighing System”  is largely dependent on the accuracy of the controls that run the system.  If the Pneumatically controlled valves are the lifeblood of the system, then the control system is the brain. This brain or in other words, the computerized control system is designed by electronic engineers.

Instrumentation and Controls of Recipe Controlled Hopper Weighing System:

Now look the Fig-2 below.

instrumentation_recipe based_hopper weighing_by_electronics15.com

 Fig -2 

Fig-2 is the “Instrumentation and controls of the Recipe Controlled Industrial Hopper Weighing System”. This is a part of in-plant material handling system, and also called “Batch Weighing of Ingredients” to deliver bulk solids into a batch process.

The Instrumentation and controls in the system includes:

  • Sensors (Load Cells)
  • Signal Amplifiers
  • Recipe controlled Micro-controller Module
  • I/O Devices
  • Actuators (Pneumatically controlled Gate Valves)
  • Display Modules

The basic structure of any Industrial Control System is almost same. Some parameters in manufacturing, quality control or final dispatch system has to be controlled as per pre-set requirement of the process.

The parameters are measured on site and data is transmitted either wireless or through wire to the Process Controller. Since sensors produce data in the milli-volt range, it has to be amplified before it is transmitted. In Fig-2, Load Cell is the Sensor and a Load Cell Amplifier amplifies the signal before it can be processed by the Micro-controller.

The Micro-controller is a recipe based system. The quantity of bulk solids that is to be transferred from the storage hopper to the weigh hopper can be pre-set in a batch and the exact quantity as per process requirement will be transferred to the Weigh hopper.

The flow of bulk solids from the storage hopper to the weigh hopper is controlled accurately by two pneumatically controlled gate valves, the Dribble flow valve and the full flow valve. These are also called actuators, and technical details of different types of actuators used in industries are discussed in some other blogs in this website.

The flow control is continuously monitored through the weight data received from the weigh hopper. The weigh hopper rests on three load cells placed at 120 degree apart to measure the quantity of bulk solids in the hopper.

After the exact pre-set quantity (as per recipe) of bulk solid is transferred to the weigh hopper, the controller sends a signal to the discharge gate and the material is transferred to a waiting trolley or to the conveyor. This is one batch of process control and the process continues as per requirement.

This is Part-1 of Industrial Control System where a simple recipe based hopper weighing system is explained in detail. Should you require any further clarifications, data or any design details , please click “contact us” and send your requirement, we will help you as much as possible.

Thank you reading this technical articles written by Sonu Perito.


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