NITROGEN GENERATION PROCESS
Publication Date: 2003-Sep-12
The IP.com Prior Art Database
U.S. Pat. No. 6,202,422 (Brugerolle) shows an air separation unit integrated with a gas turbine. It also describes a "nitrogen wash" column. Figure 1 shows such a column:
NITROGEN GENERATION PROCESS
U.S. Pat. No. 6,202,422 (Brugerolle) shows an air separation unit integrated with a gas turbine. It also describes a “nitrogen wash” column. Figure 1 shows such a column:
Liquid nitrogen (LIN) is pumped to the top of the column and air from the gas turbine compressor is introduced to the bottom of the column. Gaseous nitrogen product (GAN) is recovered from the top of the column, warmed up against feed air stream, and subsequently used in the gas turbine. The bottom of the column produces O2-rich liquid (ORL).
U.S. Pat. No. 6,276.171 (Brugerolle) describes a nitrogen wash column integrated with an air separation unit (ASU) producing gaseous oxygen product (GOX). An example of such integration with a typical pumped liquid oxygen (LOX) plant is shown on Figure 2. Air to the ASU is supplied by the main air compressor (MAC). It is purified to remove water, CO2, and other contaminants in the main front-end system (MFE). Air is cooled down against returning product streams in the main heat exchanger (MHX). A portion of air is further compressed by the booster air compressor (BAC) and condensed against boiling liquid oxygen in the main heat exchanger to produce gaseous oxygen product (GOX). Another portion of air is further compressed in compressor ECP, cooled down, and expanded in expander EXP to provide refrigeration. All those air streams end up in the cryogenic distillation system, which typically consists of two thermally coupled columns: higher-pressure column (HPC) and lower pressure column (LPC) and a condenser-reboiler REB. Expander air can go either to HPC or to LPC. Similarly, condensed liquid air can go to HPC, LPC, to both, or be taken in an out of the HPC, as shown on Figure 2. There are many well-know variations of this standard design with additional distillation columns, reboilers, condensers, subcoolers, and various feed and product arrangements. For example, GOX may be taken directly off the LPC (no BAC or LOX pump), or obtained from an additional oxygen-mixing column.
An additional nitrogen wash column COL is introduced to the standard design. Additional air to the column (AAIR) may come from the air separation unit main air compressor (MAC), or, in a preferred implementation, from a separate compressor (CMP). It is purified to remove water, CO2, and other contaminants in an additional front-end system (AFE), and cooled down against nitrogen product (GAN) in a separate heat exchanger (HX). Liquid nitrogen (LIN) pumped to the top of the column COL may come from the air separation unit (in this example a higher-pressure column condenser REB) or from another source. Oxygen-rich liquid from the bottom of the column (ORL) is returned to the distillation system. The purpose of the invention is twofold: 1) to increase air separation unit’s oxygen and nitrogen production, 2) to be able to operate the air separation unit and the nitrogen wash column independently of one another. For example, when the air...