IGCC Process Research Articles

97/02322 Control of gaseous contaminants in IGCC processes, an overview

In the NOXSO process a regenerable sorbent is used that removes SO2 and NOx simultaneously from flue gas generated during the combustion of coal. In this process the sorbent needs to be transported between adsorber and regenerator. For this purpose it is common practice to use a solids circulation system consisting of non-mechanical valves and conveying lines. In this paper the use of an Interconnected Fluidized Bed (IFB) reactor system is proposed and evaluated. The IFB-NOXSO process is designed for the removal of NOx and SO2 from a flue gas stream originating from a 150 MWe power plant. The IFB reactor consists of multiple reactors that are constructed in one vessel and connected by means of orifices and weirs. It is shown that the IFB reactor can be successfully used in the NOXSO process.

97/01442 Control of gaseous contaminants in IGCC processes, an overview

97/01442 Control of gaseous contaminants in IGCC processes, an overview

97/01260 Pilot scale experience on IGCC hot gas cleanup

Enviropower Inc. is developing and commercializing a simplified IGCC process which applies pressurized air-blown gasification technology and hot gas cleanup. Hot gas cleanup consists of a sulfur removal system using regenerable sorbent and a filter unit having ceramic candle filter elements. During coal gasification test runs the major emphasis in development of hot gas cleanup was focused on testing of the sulfur removal system. The ceramic filter unit testing was already in the category of routine operation. The filter cleaning strategy was mainly based on a constant cycle time using on-line pulsing with pressurized nitrogen. The filter unit is completely integrated with the control system of the pilot plant. Dust loadings below 5 ppmw in product gas and vapor-phase alkali (Na+K) concentrations below 0.05 ppmw were measured after filtration. These values are below the levels generally required by gas turbine manufacturers and well below the environmental standards. As part of the CRADA, two different types of regenerable zinc titanate sorbents (1.5ZnO{center_dot}TiO{sub 2}) were used in the test runs in the new sulfur removal system. As a result, steady-state operation of the sulfider and regenerator fluidized bed reactors linked together was obtained at design pressures and temperatures. Very high sulfur removalmore » efficiency in the sulfider with both sorbents was achieved, as well as continuous production of SO{sub 2}-containing off-gas from the regenerator.« less

Water gas shift membrane reactor for CO2 control in IGCC systems: techno-economic feasibility study

A novel reactor concept, the water gas shift membrane reactor (WGS-MR) for CO2 removal in IGCC systems has been investigated. In order to establish full insight in the possibilities of the application of such a reactor, a multidisciplinary feasibility study has been carried out comprising system integration studies, catalyst research, membrane research, membrane reactor modelling and bench scale membrane reactor experiments. The application of the WGS-MR concept in IGCC systems is an attractive future option for CO2 removal as compared to conventional options. The net efficiency of the IGCC process with integrated WGS-MR is 42.8 % (LHV) with CO2 recovery (80 % based on coal input). This figure has to be compared with 46.7 % (LHV) of an IGCC without CO2 recovery and based on the same components, and with 40.5 % (LHV) of an IGCC with conventional CO2 removal. Moreover, an economic analysis indicates favourable investment and operational costs. The development of the process is considered to be technically feasible. However, it became clear that the technology of inorganic high selective gas separation membrane manufacturing and high temperature ceramic materials engineering is not yet mature and that further development in this area remains necessary.

Catalytic decomposition of ammonia in a fuel gas at high temperature and pressure

In connection with the purification of fuel gas for gas turbines in the IGCC process to meet NO x standards and maintain the thermal efficiency of the process, tests were carried out with a 7.5 cm pressurized reactor to decompose ammonia at high temperature (700–900°C) and pressure (2 MPa) using Ni-based catalysts. The effects of temperature, pressure, ammonia concentration and gas residence time were determined. The simulated coal gas composition was varied to allow assessment of the effect of contaminants (sulfur compounds and tars) on the ammonia decomposition efficiency of five catalysts under otherwise identical operating conditions. The results show that two of the catalysts tested are capable of efficiency reducing the concentration of ammonia in the gas.

Formation and behaviour of nitrogen compounds in an IGCC process

A summary of the latest available information on the formation and decomposition of nitrogen compounds in gasification, hot-gas cleaning, and gas combustion is presented. When nitrogenous fuels are gasified, nitrogen compounds are formed in gas from fuel nitrogen. In pressurized high-temperature fluidized-bed and entrained-bed gasifiers, NH 3 is the primary nitrogen compound. Very little HCN is formed in these types of gasifier. The most important factors correlating with the NH 3 content of the gas seem to be gas temperature and fuel quality. The NH 3 content of the gas can be reduced by catalysts or by feeding oxidizers to the gas. CH 4 reduces the decomposition rate of NH 3.