Technology of oxygen production in the membranecryogenic air separation system for a 600 MW oxy-type pulverized bed boiler

Abstract

In this paper the results of the thermodynamic analysis of the oxy-combustion type pulverized bed boiler integrated with a hybrid, membrane- cryogenic oxygen separation installation are presented. For the calculations a 600 MW boiler with live steam parameters at 31.1 MPa /654.9 oC and reheated steam at 6.15 MPa/672.4 oC was chosen. In this paper the hybrid membrane-cryogenic technology as oxygen production unit for pulverized bed boiler was proposed. Such an installation consists of a membrane module and two cryogenic distillation columns. Models of these installations were built in the Aspen software. The energy intensity of the oxygen production process in the hybrid system was compared with the cryogenic technology. The analysis of the influence of membrane surface area on the energy intensity of the process of air separation as well as the influence of oxygen concentration at the inlet to the cryogenic installation on the energy intensity of a hybrid unit was performed.

The Characteristics of a Modern Oxy-Fuel Power Plant

“…The variant V2 of an oxy-type power plant was equipped with a hard-coal-fired, pulverized-fuel boiler and a hybrid air separation unit [61][62][63][64]. A schematic diagram of both installations is presented in Figure 5.…”

“…The difference is that an additional single-stage membrane separator is used in the structure in order to raise the oxygen content at the inlet to the cryogenic part of the ASU. The membrane installation was modeled in the Aspen Custom Modeler 2004 [61][62][63][64]. Such changes in the ASU's structure greatly reduce the flow rate of gas through the compressors and the cryogenic installation; thus, the auxiliary power of the ASU is reduced as well.…”

“…The authors in the literature [61][62][63][64] analyzed low-temperature separation membranes made of the following four materials: polyethylene oxide (PPO), Matrimid, phenolic resin, and carbon/ZSM5. Based on these analyses, phenolic resin was chosen as the best of the materials that were considered.…”

“…The CC unit can be divided into two main parts. In the first, the flue gas was: • Variant V1-an oxy-type power plant equipped with a lignite-fired, fluidized-bed boiler and cryogenic ASU [59,60]: • Variant V2-an oxy-type power plant equipped with a hard-coal-fired, pulverized-fuel boiler and hybrid ASU (membrane-cryogenic) [61][62][63][64]; • Variant V3a-an oxy-type power plant equipped with a lignite-fired, fluidized-bed boiler and ASU with a three-end type, high-temperature membrane (HTM) [65,66]; • Variant V3b-an oxy-type power plant equipped with a hard-coal-fired, pulverized-fuel boiler and ASU with a four-end type, high-temperature membrane (HTM) [3,67,68].…”

Thermodynamic evaluation of supercritical oxy-type power plant with high-temperature three-end membrane for air separation

“…For separation of air various methods are used. The most common solution for air separation is a relatively high energy consuming cryogenic separation [5][6][7][8], therefore, as a part of the searching for alternatives to cryogenic technology the high-temperature membranes (HTM) were decided to be used in this process [9,10].…”