Precision and reliability are achieved by merging Saimo latest in-motion weighing technology and the specially designed digital controller. It is widely used for fuel control, inventory monitoring and reporting for all kinds of pressurized boiler applications in power plant, chemical industry and coal mine.
Theory of Operation
For typical coal powder boiler applications, the coal feeder is usually mounted under the bunker to continuously deliver the specified coal flow into the pressurized mill. The coal feeder is connected to the bunker via an inlet chute to allow positive coal loading on the belt of the coal feeder.
The two high precision strain gauge load cells positioned under the weighbridge provide real-time coal weight as the belt loading passes through the weigh area. Belt speed is continually measured with a digital speed sensor whose pulse output is proportional to belt speed.
The speed sensor is mounted on the tail-pulley to assure accurate belt speed measurement and detection of any possible slippage.
The speed signal and weight signal are combined in the microprocessor-based integrator totalizer which generates and displays a true-rate signal in TPH and the total of material fed.
A controller compares the rate signal to the setup feed rate (set from a host computer, PLC or by manual command) and generates the necessary output signal to the frequency converter by means of PID regulation, changing the feeder’s belt speed to maintain the desired constant rate of material fed. This in-motion adjustment operation ensures continuous and constant coal feeding into the coal mill.
Features of SAIMO Pressure-resistant Gravimetric Coal Feeder Model: F55
- Rugged pressure-resistant housing, tightly sealed to prevent air and coal dust leaks, capable of withstanding 0.35Mpa explosion pressure.
- Packing seal for all extruding shafts, ensuring pressure-resistant performance.
- Plug-in slot design for the access doors, and blind hole on the inspection port for effective sealing
- Seal air joint with multipoint exhaust structure for efficient isolation from hot air.
- Flat idler construction, and endless corrugated belt made of fireproof rubber with up to 40mm skirt-edge height.
- Powerful drive pulley lagged in rubber herringbone pattern, preventing belt misalignment.
- Crowned driven pulley eliminating belt misalignment.
- Screw take-up device fixed outside the housing for belt running in tension, reducing belt slippage and misalignment.
- An automatic belt deviation correcting device equipped on the return belt for self-correction of belt misalignment.
- Pulleys supported by pillow block bearings with provision for field re-lubrication outside the casing.
- Steel-surface cylindrical idler, 89mm in diameter, allowing increased accuracy by reducing idler roller run-out.
- Gravity type scraper utilized for exterior belt cleaner and V-shaped rubber scraper for interior cleaner.
- A chain scraper conveyor mounted at the bottom of the coal feeder, removing flying dust.
- Access door installed on either side of the coal feeder, and inspection port for easy maintenance.
- Several lamps mounted on the feeder body, with bulb easily replaced without interrupting the process.
- A sliding guideboard adjustable for truing coal flow.
- Weighbridge supported on two load cells effectively compensates for errors due to off-center loading
- Test weight calibration facility
- Speed sensor installed on the tail pulley minimizes the error due to belt slippage.
- Premium weigh feeder controller based on 32-bit microprocessor with a 20-bit A/D converter for quick and accurate operation, as well as diversified inputs/outputs and communication interfaces.
- Direct coupled, sprocket transmitted or shaft mount drives available
- In-process Auto-zeroing (IPAZ) feature, ensuring high precision
- Belt tension measuring system, ensuring accuracy and belt rip detection
- Inlet gate valve, manual or automatic control selectable.
- Discharge gate valve Manual, rapid cut-off style, pneumatic or electric control selectable.
- Customized inlet structure, in compliance with specific requirements