Control system and method for a synthesis gas process

A synthetic gas generator receiving oxygen and natural gas through separate pipes provides synthetic gas. The methane content of the synthetic gas is sensed and a corresponding methane signal is provided. Carbon monoxide and fuel hydrogen are removed from the synthetic gas and provided in different pipes. The pressure of the carbon monoxide is sensed and a corresponding pressure signal is provided. Control apparatus controls the oxygen and natural gas entering the synthetic gas generator in accordance with the methane signal and the pressure signal.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to a control system and method for a 
synthesis gas process. 
SUMMARY OF THE INVENTION 
A synthesis gas generator receiving oxygen and natural gas through separate 
pipes provides synthesis gas. The methane content of the synthesis gas is 
sensed and a corresponding methane signal is provided. Carbon monoxide and 
fuel hydrogen are removed from the synthesis gas and provided in different 
pipes. The pressure of the carbon monoxide is sensed and a corresponding 
pressure signal is provided. Control apparatus controls the oxygen and 
natural gas entering the synthesis gas generator in accordance with the 
methane signal and the pressure signal. 
The objects and advantages of the invention will be described more fully 
hereinafter from a consideration of the detailed description which 
follows, taken together with the accompanying drawing wherein one 
embodiment of the invention is illustrated by way of example. It is to be 
expressly understood, however, that the drawing is for illustration 
purposes only and is not to be construed as defining the limits of the 
invention.

DESCRIPTION OF THE INVENTION 
Referring to the FIGURE, there is shown an existing commercial process 
which includes a synthesis gas generator 5 receiving oxygen by way of a 
line 8 and natural gas by way of a line 11 and providing synthesis gas to 
an acid gas removal means 17 by which carbon dioxide and hydrogen sulfide 
are removed from the synthesis gas. The output from means 17 is provided 
to a cryogenic means 24 for cooling. Cryogenic means 24 provides carbon 
monoxide by way of a line 28 and fuel hydrogen by way of line 30. 
Cryogenic means 24 also provides high pressure hydrogen to an absorption 
means 35 which purifies the hydrogen and provides high pressure hydrogen 
by way of line 39. Absorption means 35, when at a high pressure, absorbs 
contaminants and when at a low pressure regenerates the absorption 
material within it. 
All of the foregoing is for an established in-use process. The present 
invention provides a control system for that process so as to control the 
oxygen and natural gas being provided to synthesis gas generator 5. In 
this regard, a flow transmitter 44 and a valve 46 is located in line 8. 
Flow transmitter 44 senses the flow of the oxygen and provides a 
corresponding signal to a flow controller 50. Flow controller 50 provides 
a signal to valve 46 to control the flow of oxygen entering synthesis gas 
generator 5 in accordance with flow controller 50 set points as 
hereinafter described. 
Similarly, a flow transmitter 54 and a valve 56 are located in line 11 and 
cooperate with a flow controller 60 in a similar manner as controller 50 
to control the flow of natural gas entering synthesis gas generator 5. A 
pressure sensor located in line 28 senses the pressure of the carbon 
monoxide being provided by cryogenic means 24 and provides a signal to 
flow controller 60 so as to control the flow of natural gas as a function 
of the pressure of the carbon monoxide. 
Flow recorder 60 in addition to providing the signal to valve 56 also 
provides the signal to a proportional controller 67. Infrared analyzer 70 
samples the gas leaving synthesis gas generator 5 and provides a signal 
corresponding to the methane content of the gas to proportional controller 
67. Proportional controller 67 provides a signal to controller 50 to 
adjust its set points so as to control the flow of oxygen as a function of 
the natural gas content and the methane content of the synthesis gas.