1) Main control and shut-off valve for oxygen to burner
It operates with pure oxygen at an operating pressure of up to 90 bar and a temperature of approximately 40 °C. Pressure drops are minimal during operation; the valve however, must reliably isolate when subjected to 90 bar (leakage rate V). Arca Ecotrol® Series 6H7-P1 control valves, with housing and internal parts made from Monel® or Inconel®, are reliably used.
2) Control valve for oxygen to inner burner
The operating conditions are identical to those for the main control and shut-off valve. Arca Ecotrol® Series 6H1-P1 control valves with housing and internal parts made from Monel® or Inconel® 625 are used due to their smaller nominal size.
3) Blow-off valve for oxygen service
This blow-off valve is used to divert oxygen to the atmosphere when the plant is started up and shut down. Its design and downstream fixed valve stages must, therefore, be able to withstand an operating differential pressure of up to 90 bar. This valve remains closed and is required to be leaktight at 90 bar when the plant is operated under normal conditions (leakage rate V) to minimise the loss of high value oxygen. The valves used in this application are the Arca Ecotrol® Series 6H7-L3 control valves with a downstream LS3 diffuser plate where the housing and internal parts as well as the diffuser plate are made from Monel® or Inconel®. All Arca control vakves for oxygen service
Even though safety standards in the gas processing industry are at a high level there are frequent accidents in the handling of oxygen. The existing EIGA safety regulations which are incorporated in the valve design are applied during the manufacture, assembly and various tests, and require an extremely reliable and skilled work force. All Arca cointrol vakves for oxygen service are prepared according to the apporpriate standard in Arca's oxygen cleaning facility in Germany.
4) Control valve for nitrogen service
This valve ensures that the plant is inert when it is started up or shut down and during emergency shutdowns. Nitrogen pressure (typically 130 bar) is considerably higher than the operating pressure of the plant. The nominal size of the Arca Ecotrol® 6H1-P1 control valve ranges from 1" to 1 ½" (DN25 to DN40). These valves are requierd to be leaktight to prevent any nitrogen from entering the plant during normal operation. Stainless steel valve housing and internal parts provide sufficient strength, since nitrogen is all that flows through the valve at this stage of operation and oxygen is only present when the valve is closed.
5) Control valve for injecting steam into the coal slurry
A specific amount of high-pressure steam is injected into the coal slurry to disperse it and set the stoichiometric reaction process. The available steam will have a pressure in excess of 100 bar and a temperature of approximately 540 °C. The Arca Ecotrol Series® 6H1-L1 control valve made from high temperature cast steel ASTM A217 WC9 (DIN 1.7379) are used for this application.
6) Main control valve for Syngas
This control valve maintains pressure in the reactor/gas scrubber and regulates the flow of Syngas to the downstream process. These valves have a large nominal size typically 12" (DN 300) in order to manage the high-velocity gas stream and are almost always the Arca Ecotrol® 6H7-L1-LN Series. Control valves used on Syngas are made from cast steel, with a specially designed leaktight stuffing due to the high concentration of poisonous carbon monoxide.
7) Blow-off valve for Syngas to flare
Additional Arca Ecotrol® Series 6H7-P1 shut-off valves are typically used in addition to the flare control valve to direct Syngas to the flare. These valves will have a soft seat, as they are designed for a maximum CV value and low differential pressure. This soft seat ensures that no Syngas flows into the flare when the plant is operating under normal conditions.