Chiller, air separation system, and related methods

A method of cooling air in an air separation unit (ASU) of a plant, the plant also having a gasification section, the method comprising:

• positioning at least one absorption chiller in the ASU to receive at least one process stream from the gasification section so heat from the at least one process stream from the gasification section is feedable to at least one generator of the at least one absorption chiller;
• providing cooling via the at least one absorption chiller to facilitate:
• (i) cooling air at a first pressure from a compression system of the ASU for feeding the cooled air to a pre-purification unit (PPU) for purification of the air to form a purified air flow for feeding the purified air flow to a cold box of the ASU,
• (ii) cooling the purified air flow from the PPU before the purified air flow is fed to the cold box, and/or
• (iii) cooling the air at a second pressure from the compression system of the ASU for feeding the cooled air at the second pressure to the compression system to undergo further compression to the first pressure, the first pressure being higher than the second pressure;
• wherein the at least one absorption chiller includes a primary absorption chiller and a secondary absorption chiller, the method also comprising:
• one of:
• in response to one or more sensors determining that an impurity concentration level is at or above a pre-selected threshold, adjusting operations of the at least one absorption chiller so that a first portion of the air at the first pressure from the compression system is fed to the primary absorption chiller and a second portion of the air at the first pressure from the compression system is fed to the secondary absorption chiller, and
• in response to one or more sensors determining that the impurity concentration level is at or above the pre-selected threshold, adjusting operations of the at least one absorption chiller so that (i) a first portion of a cooling medium to be fed to a direct contact cooler, the direct contact cooler for cooling the air at the first pressure from the compression system, is fed to the primary absorption chiller, the primary absorption chiller to cool the first portion of the cooling medium to a pre-selected direct contact cooler chilling medium inlet temperature and (ii) a second portion of the cooling medium to be fed to the direct contact cooler for cooling the air at the first pressure from the compression system, is fed to the secondary absorption chiller, the secondary absorption chiller to cool the second portion of the cooling medium to the pre-selected direct contact cooler chilling medium inlet temperature.