We offer reliable control solutions for all process steps in the coal gasifier.
1) Oxygen main flow control valve
The medium is pure oxygen at operating pressure of up to 90 bar and approx. 40 °C. The pressure drop is low during operation, but during start-up and shutdown the valve in the coal gasifier must control and shut off safely against 90 bar differential pressure (leakage rate class V). ARCA control valves with housing and internal parts made of Monel® or Inconel® are used here.
2) Inner burner oxygen control valve
The operating conditions are identical to those on the main control valve/shut-off valve. Also here, ARCA valves with housings and internal parts made of Monel® or Inconel® 625 are used here.
3) Oxygen blow-off valve
This valve is used to dissipate the oxygen into the atmosphere when the coal gasifier is started and shut down. Consequently, this valve, together with the downstream fixed stages, must be designed for an operating differential pressure of approx. 90 bar. During normal operation of the plant, this valve is closed and must seal leak-tight to 90 bar operating pressure (leakage rate class V) so that the loss of oxygen remains as low as possible. The valves used here are made by ARCA with downstream LS3 perforated disc assembly; only Monel® or Inconel® are suitable as material for housings and internal parts, as well as for the perforated discs.
4) Nitrogen control valve
This valve is used to inert the coal gasifier system during start-up and shut-down as well as during emergency shutdown. The nitrogen pressure is significantly above the operating pressure of the plant, typically 130 bar. The nominal size of the ARCA control valves used is DN 25 to DN 40 (1″ to 1 ½”). These valves must also be technically leak-tight so that no nitrogen is introduced into the coal gasifier during normal operation. Since only nitrogen flows through the valve at this point when operating and oxygen is only available when the valve is closed, a valve with housing and internal parts made of stainless steel is sufficient here.
5) Syngas pressure control valve
This valve is used to maintain pressure in the reactor/gas scrubber and to control the gas flow to the downstream process. Due to the high gas flow, these are valves with a large nominal size (typically DN 300 / 12″) from the ARCA series. The valves for syngas are made of high temperature cast steel, but due to the high proportion of toxic carbon monoxide, the leak-tightness of the stuffing box is of great importance. Additionally, due to the residual amount of particles in the syngas, this is a really challenging service.
6) Syngas blow-off valve to flare
This is the valve that controls the syngas flow to the flare during startup and shutdown of the plant as well as in emergency situations. The fluid is same as on the syngas pressure control valves, means the requirements for stuffing box tightness and resistance against particles are the same. Since the downstream pressure is close to atmosphere, downstream flow resistors are used to limit the outlet flow velocity and the noise emission. These valves must be tight to Leakage Class V to avoid loss of syngas during normal operation.