KST – KROMSCHRÖDER SYSTEM TECHNOLOGY

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Process Control Systems

overview

Multiple burner system, pilot and main burners, modulating-controlled (zone)

Multiple burner system, modulating (zone control), no air preheating, Pilot burner, pneumatic ratio control system, Ionization control
Flowchart No.: 2.3.1.2.1.1
Standard: EN 746-2

Burners
No. Component description Standards and Docuthek
100 Power supply unit
210 Combustion air fan
300 Safety limits
311 Air min. air pressure monitor, e.g. DG
321 Gas min. low-pressure cut-off, e.g. pressure switch for gas DG
322 Gas max. high gas pressure protection, e.g. pressure switch for gas DG
331 Emergency stop/Emergency off/Gas off, e.g. Emergency Stop button NTA
332 Overtemperature ϑ max
341 Pre-purge
350 Valve proving system, e.g. tightness control TC 1-3
350 Valve proving system, e.g. tightness control TC 410
410 Valve control
450 Burner control unit BCU 480

The burner control unit is mounted to the burner on site and ensures simple commissioning of the burner system.

450 Automatic burner control unit PFU 780

Automatic burner control units for monitoring and control of gas burners.

510 Temperature control

Application

Process control system (PCC) for control and continuous zonal temperature control of the pilot and main burners in a multiple burner system, ionization-controlled with gas and cold air supply.

Function

The supply voltage is supplied to the control system via the power supply unit (100).

Start-up of the combustion air fan (210) includes the “no flow” state check of the Air min. air pressure monitor (311).

The control block for monitoring the safety limits (300) assumes the safety-related monitoring of the safety limits Air min. air pressure monitor (311), Gas min. low-pressure cut-off (321), Gas max. high gas pressure protection device (322), Emergency stop/Emergency off/Gas off (331) and ϑ max. overtemperature monitor (332).

Once the system has started and all safety limits (300) are present, pre-purging (341) of the thermoprocessing equipment begins and the tightness control (350) checks the automatic shut-off valves. Once pre-purge (341) has been completed and the OK signal has been issued by the tightness control (350), the safety interlocks (shown in yellow) are set and the pilot burners are started. Once the pilot burner flame signal has been received by the associated automatic burner control unit (450), the main burner is started in the ignition position. The burners are set to the ignition position zone by zone by the valve control system (410). Once the presence of the flame has been signalled to the associated automatic burner control unit (450), the burner starts.

Once all burners are operating, the temperature controller (510) takes over the temperature control of the zone.

Note

A system fault lock-out occurs if

  • at least one of the safety limits does not lie within the system operating range
  • or the tightness control (350) has detected a leak on the main gas valves or burner valves
  • or the automatic burner control unit (450) has detected a burner fault.

The system fault lock-out may only be reset manually.

The safety limits listed refer to a typical item of thermoprocessing equipment. The required safety limits may differ, depending on the system type.

If the automatic shut-off valves of each burner are controlling capacities of over 1200 kW, a tightness control (350) must be fitted in accordance with EN 746-2:2010.

In the diagram, a BCU 480 is shown for the automatic burner control unit (450). If another control unit is used, some signals must be provided by an additional control logic.

The LDS (limit during startup) input of the automatic burner control unit (450) must be implemented by an additional control logic.

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