Apparatus and method for optimizing a liquefied natural gas facility

A method comprising:

• determining how to adjust one or more manipulated variables using at least one model, the one or more manipulated variables and one or more controlled variables associated with a cascade liquefied natural gas facility, one of the one or more controlled variables associated with an overall load placed on multiple refrigeration systems in the cascade liquefied natural gas facility;
• and
• generating one or more control signals for the cascade liquefied natural gas facility, the one or more control signals adjusting operation of the cascade liquefied natural gas facility so as to (i) maintain the one or more controlled variables within defined limits and (ii) increase the overall load placed on the refrigeration systems;
• wherein generating the one or more control signals comprises identifying a maximum of:
• (i) a first projected feed gas rate to operate a propane refrigeration system at a propane maximum load, (ii) a second projected feed gas rate to operate an ethylene or ethane refrigeration system at an ethylene/ethane maximum load, and (iii) a third projected feed gas rate to operate a methane refrigeration system at a methane maximum load.

A computer readable medium embodying a computer program, the computer program comprising:

• computer readable program code for determining how to adjust one or more manipulated variables using at least one model, the one or more manipulated variables and one or more controlled variables associated with a cascade liquefied natural gas facility, one of the one or more controlled variables associated with an overall load placed on multiple refrigeration systems in the cascade liquefied natural gas facility;
• and
• computer readable program code for generating one or more control signals for the cascade liquefied natural gas facility, the one or more control signals configured to adjust operation of the cascade liquefied natural gas facility so as to (i) maintain the one or more controlled variables within defined limits and (ii) increase the overall load placed on the refrigeration systems;
• wherein the computer readable program code for generating the one or more control signals comprises computer readable program code for identifying a maximum of:
• (i) a first projected feed gas rate to operate a propane refrigeration system at a propane maximum load, (ii) a second projected feed gas rate to operate an ethylene or ethane refrigeration system at an ethylene/ethane maximum load, and (iii) a third projected feed gas rate to operate a methane refrigeration system at a methane maximum load.

A method comprising:

• determining how to adjust one or more manipulated variables using at least one model, the one or more manipulated variables and one or more controlled variables associated with a cascade liquefied natural gas facility, one of the one or more controlled variables associated with an overall compressor loading for multiple refrigeration systems in the cascade liquefied natural gas facility;
• and
• generating one or more control signals for the cascade liquefied natural gas facility, the one or more control signals adjusting operation of the cascade liquefied natural gas facility so as to (i) maintain the one or more controlled variables within defined limits and (ii) increase the overall compressor loading;
• wherein generating the one or more control signals comprises identifying a proximity of the overall compressor loading to a maximum load by identifying a largest of:
• (i) an amount of additional feed that can be processed in a propane refrigeration system up to a propane maximum load, (ii) an amount of additional feed that can be processed in an ethylene or ethane refrigeration system up to an ethylene/ethane maximum load, and (iii) an amount of additional feed that can be processed in a methane refrigeration system up to a methane maximum load.