CONTROL OF SEPARATOR FOR VERY COLD LIQUEFIED GAS

摘要

PURPOSE:To eliminate a delay in the response of a control system and make it easy to change the setting for the quantity of product liquid by adding to a primary buffer the quantity corresponding to the quantity of change at the time when a set value of the quantity of the product liquid is made and outputting gradually the quantity in the primary buffer for controlling the load of an expansion turbine. CONSTITUTION:An adder 15 for feed-forward is provided at an intermediate point in the signal from a liquid level adjustor 13 to a valve 4 at the inlet of an expansion turbine to carry out the calculation of the amount (MV) of feed-forward for the change of a set value from a flow rate control system and output the output value from the liquid level adjustor 13 with MV added. The product of the amount of change in the setting and a coefficient is added to the amount (FFB) of buffer of the feed-forward and it is outputted gradually until FFB becomes zero which was once stored. With this arrangement the feed-forward receives only the necessary amount and no sudden variation is affected to the expansion turbine.