Introduction

• Информационные материалы

  Информационные материалы

  SITRANS weighfeeders from Siemens can improve the accuracy of processing, blend consistencies, accountability, and record keeping. All weighfeeders come standard with a belt weigh bridge and speed sensor. An integrator is required to complete the system.

  Область применения

  

  Weighfeeder Application Questionnaire 

  Способ действия

  The weighfeeder is used to deliver an accurate mass flow rate of material. In the majority of applications, material is profiled by an adjustable mechanical shear gate, which fixes the correct material bed depth for a given particle size.

  The feed rate is then maintained and adjusted by varying the speed of the belt. However, in some cases the belt speed is constant with rate control (if any) done by a pre-feeding device.

  The system consists of three components: weight and speed sensing, integration and control, and the mechanical conveying system. Using the belt load and the belt speed signals, small incremental totals of weight per time are measured by the integrator and then the flow rate is calculated. The measured flowrate is compared against the desired flowrate and the on-board PID controller makes necessary corrections to the belt speed.

  

  Weighfeeder operation

  Design and Applications

  SITRANS WW100

  The platform weigh bridge mounts directly to a corrosion-resistant platform load cell. The direct load design eliminates all intermediate mechanical suspension and allows material weight to be directly applied to the load cell.

  This design minimizes zero drift normally caused by intermediary suspension components and allows for the use of a very sensitive precision platform load cell. Load cell size and construction are chosen for each specific application.

  SITRANS WW200

  A stainless steel platform weighdeck with a Delrin slider bar assembly mounts directly to two corrosion-resistant, sealed platform load cells. The direct load design eliminates all intermediate mechanical suspension and allows material weight to be directly applied to the load cells. The frame of the WW200 is sturdy and rigid, ensuring stable and repeatable results, maximizing resolution and weighing accuracy.

  SITRANS WW300

  SITRANS WW300 suspends a single weigh idler on platform load cells. Its design eliminates all moving parts in the weighing
  process and subsequent maintenance and replacement problems. There are no links or flexures. Two corrosion-resistant precision strain gauge load cells provide weight sensing signals to an integrator. This design feature minimizes zero drift and maximizes
  resolution and weighing accuracy.

  SITRANS WW310

  A modular design with external access to all bearings, speed sensors and load cells the WW310 is easy to maintain. Two corrosion resistant single point platform load cells mounted directly to a rugged idler ensure consistent weighing accuracy.

  SITRANS WW500

  This robust weighfeeder uses an endless series of overlapping pans mounted on heavy duty chains. The pans move on heavy duty rollers mounted on a rigid frame structure. The unique weigh system reduces dead load and applies live load directly to load cells for accurate measurement, without the use of check rods, pivots, or bearings. The four load cells are mounted below the apron pans to ensure protection and help with heat dissipation. Proven to enhance profitability by ensuring accuracy and accountability while reducing downtime.

  Технические данные

  Criteria	SITRANS WW100	SITRANS WW200	SITRANS WW300	SITRANS WW310	SITRANS WW500
  Typical industries	Bulk chemicals, tobacco, food, water treatment	Bulk chemicals, tobacco, food, recycling	Cement, mineral processing, coal, mining, pulp and paper	Cement, mineral processing, coal, mining, pulp and paper	Cement, steel, power generation, and other heavy-duty industries
  Typical applications	High-accuracy, low-capacity for minor ingredient additives	Low- to medium-capacity for minor ingredient additives	Medium- to high-capacity for macro ingredient additives	Medium- to high-capacity for macro ingredient additives	Medium-to high capacity for macro ingredient additives
  Design rate range	45 kg/h ... 18 t/h (100 lb/h ... 20 STPH)	0.45 ... 100 t/h (1 000 lb/h ... 110 STPH)	4.5 ... 800 t/h (5 ... 880 STPH)	4.5 ... 270t/h (5 ... 300 STPH)	10 ... 2 000 t/h (11 ... 2 200 STPH)
  Belt speed	0.005 ... 0.36 m/s (1 ... 70 fpm)	0.005 ... 0.36 m/s (1 ... 70 fpm)	0.005 ... 0.36 m/s (1 ... 70 fpm)	0.005 ... 0.36 m/s (1 ... 70 fpm)	-
  Pan speed					0.01 ... 0.25 m/s (2 ... 50 fpm)
  Accuracy1)	± 0.25 ... 0.5 %	± 0.5 % or better	± 0.5 % or better	± 0.5 % or better	± 2 % or better
  Specified range	10 ... 100 % based on speed	10 ... 100 % based on speed	10 ... 100 % based on speed	10 ... 100 % based on speed	33 ... 100 % based on speed
  Sensing element	Long length platform weigh bridge Single load cell	Platform weigh bridge Dual load cells	Single idler scale Dual load cells	Single idler scale Dual load cells	Pan supports on four load cells
  Approvals	CE, RCM Stainless steel options meet USDA and FDA requirements for food processing	CE on all electrical components, hazardous approvals per configuration options Stainless steel options meet USDA and FDA requirements for food processing	CE on all electrical components, hazardous approvals per configuration options	CE on all electrical components, hazardous approvals per configuration options	CE on all electrical components, hazardous approvals per configuration options

  
  
  

  1) Accuracy subject to: On factory approved installations the weigh feeder system’s totalized weight will be within the specified accuracy when compared to a known weighed material test sample. The test rate must be within the specified range of the design capacity and held constant for the duration of the test. The minimum material test sample must be equivalent to a sample obtained at the test flow rate for three revolutions of the belt or at least ten minutes running time, whichever is greater.