Belt Conveyor is the basic material handling equipment in plant. Belt conveyor is a simple equipment consisting of Idlers, Pulley conveyor belting drive, reducer, take-up etc.Substantial fabricated frames support the heavy components like Pulleys, take-up and drive mechanism.

1. BeltFunction: To convey or transport material. 1a. Upper strand (generally the load carrying strand). 1b. Lower strand (generally the return strand).

2. Load Carrying RollersFunction: To support the belt and reduce its resistance to movement of the load. Some load carrying rollers may also be impact reducing, self-aligning, trough forming or be able to change the inclination of the belt.3. Return RollersFunction: To support the belt and reduce resistance to movement. Some return rollers may also be self-aligning or be able to change the inclination of the belt.4. DrumsFunction: To drive a belt or re-orient the direction of travel. Types of drums: 4a. Live drum - drives the belt by being itself driven by a motor. 4b. Head drum - returns the belt to the lower strand (and may also serve as a live drum). 4c. Tail drum - returns the belt to the upper strand. 4d. Snub drum - aligns the entering or exiting strand with the lower strand or ensures the required area of contact with the live drum. 4e. Tensioning drum - maintains proper belt tension by way of a take-up system.

5. Take-Up SystemFunction: To ensure proper belt tension. Types of systems: 5a. Gravity system - a guided weight pulls the tensioning drum to provide the required tension. 5b. Manual or self-adjusting system - adjustment screws or automatic control systems provide the required tension.6. Power Transmission Moving PartsFunction: To produce and transmit the required energy to the live drum for moving or restraining the belt. Many combinations are possible: > The motor and speed reducing units are connected by couplings.7. Loading SystemFunction: To guide and control the load feed on the belt . There are many possible systems: hoppers, chutes, automatic loaders, pushers, etc. 7a. Hopper assembly - Guides, contains and sometimes controls the bulk load feed. 8. Unloading MechanismFunction: To guide the load exiting the conveyor system CHUTES are used.

Belt conveyors are probably the most efficient means of transporting bulk materials. However, they are considered dangerous due to the sheer size of the installation which prevents clear and unimpeded visibility down the length of the system. Conveyors can be one of the most hazardous mine or plant equipment installations if safety regulations are not strictly followed or if the conveyors are not properly maintained.

Pull-cord stations are distributed stop switches with latching attachments. Pull-cord or pull-wire switches are required on all conveyors. Pull-switches are located along the conveyor at intervals not exceeding 100 meters between the individual switch units. The units are interconnected with a pull-wire. An operator activates the switch by pulling the pull-cord until the switch trips, interrupting power to the conveyor and usually raising a visual indicator flag. The switch remains tripped until reset manually at the switch location. The belt does not restart on reset of the pull-cord for safety reasons. The pull force required to operate the switch shall not exceed 70 N when applied at mid span between supports, with a movement of not more that 300 mm.

Pull-wires must be installed in such a way that they are clearly visible and readily accessible from all areas that provide access to the conveyor.

It is important that the belt stays aligned with the drive pulleys and the carrying and return idlers. Belt alignment sensors are typically positioned along the edges of the conveyor fabric. They are usually located at the discharge and at the loading areas of the conveyor, but can be distributed along the conveyor at intervals, depending on the conveyor route and the requirement.

Conveyor belts should be interlocked for the safety of men and material.Classically, interlock is the run permissive for the conveyor to any other unit's run status. Interlock normally proceeds through a system in the reverse order of material flow. For example, a belt conveyor numbered ROM1 transfers material to another belt conveyor numbered RC1. Conveyor ROM1 is interlocked to RC1. If conveyor RC1 shuts down, ROM1 must shut down. Interlock then flows from RC1 to ROM1.

Implementation of sequence operation of conveyors is challenging yet simple , as it involves only digital logic implementation using sensors, relays, and contactors.Conveyor belts are interlocked in the reverse order of coal flow. At present in CHP SRP conventional interlock logic is used. ie If ROM1 is to be run after RC1. ROM1s main contactor contains auxiliary NO contact of RC1 in series. Hence RC1 and ROM1 are interlocked.The same logic can also be implemented using PLCs. Use of PLC eliminates cumbersome wiring of contacts. As whole logic is implemented by program. Only input Output wiring is required.

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