Control scheme for conversion of variable composition synthesis gas to liquid fuels in a slurry bubble column reactor

In a process comprising converting, in a slurry bubble column reactor containing a catalyst, a synthesis gas stream comprising hydrogen and carbon monoxide into a product stream and a purge gas stream wherein:

• (1) a portion, if any, of the purge gas stream is recycled to the synthesis gas stream entering the SBCR as a purge gas recycle stream;
• (2) a water stream is added, if at all, to the synthesis gas stream entering the SBCR;
• (3) a portion, if any, of the synthesis gas feed bypasses the SBCR as a synthesis gas bypass stream and is combined directly with the purge gas stream;
• and
• (4) the synthesis gas stream has an oscillating carbon to hydrogen ratio;
• the improvement comprising a control scheme responsive to said oscillating carbon to hydrogen ratio in the synthesis gas stream, said control scheme comprising:
• (i) increasing or commencing the flow in the purge gas recycle stream in step (1) as the ratio goes up and decreasing or terminating the flow in the purge gas recycle stream in step (1) as the ratio goes down;
• and/or
• (ii) increasing or commencing the flow in the water stream being added to the synthesis gas stream in step (2) as the ratio goes up and decreasing and/or terminating the flow in the water stream being added to the synthesis gas stream in step (2) as the ratio goes down;
• and/or
• (iii) decreasing or terminating the flow in the synthesis gas bypass stream in step (3) as the ratio goes up and increasing or commencing the flow in the synthesis gas bypass stream in step (3) as the ratio goes down.