IGCC

Integrated gasification combined cycle (IGCC) power plants have become more attractive after the
emission regulations of the thermal power plants. IGCC power plants enable to control emissions which cause global
warming. Low grade lignites, biomass and wastes can be utilized by this technology. This study deals with the
thermodynamic analysis of an IGCC power plant. Energy and exergy analysis are carried out for a Texaco type
gasifier, one stage, oxygen blown and slurry fed. Cold gas cleaning (fuel gas treatment) system is considered for the
simulations, performed in THERMOFLEX software. A parametric study is also carried out to show the effects of the
O2 purity, fuel supply temperature, gasifier temperature and H2O content of the slurry to the IGCC performance. Net
power and net electric efficiency are calculated to be 389.669 MW and 43.53% respectively. Exergy efficiency of the
simulated IGCC is found to be 40.36% and the highest exergy destruction is observed in gasifier and the combustion
chamber of the gas turbine.

ISAB Energy – ERG Group - operates in Priolo Gargallo (Sicily-Italy) since year 2000 the 550 MW IGCC Plant located nearby 16 Mton per year ERG Refinery.
The IGCC produces electric power using very heavy fuel oil as feedstock in a plant made up of different units; mainly:
- solvent Deasphalting
- gasification, carbon recovery and recycle
- syngas cooling and water condensation and recovery
- acid gas removal
- sulphur recovery
- hot oil system
- sea water desalination
- combined cycle unit (CCU) equipped with SCR for DeNOx and fogging system for combustion air cooling
- pure hydrogen production system
Environmental aspects are key issues for the plant and BAT (best available techniques) have been implemented for the reduction of:
- SOx emissions
- NOx emissions
- Particulate emissions
- Sweet water consumption
Core of the process is made of two gasifiers licenced by General Electric (GE Energy) and a Combined Cycle Unit designed, built and maintained by Ansaldo Energia under Siemens license.
This article will cover the following issues:
- Description of the plant and its development, construction and start-up phases
- Description of the techniques implemented for the minimization of environmental impacts
- Key performance indicators for availability, reliability and emissions.

In this paper a one-dimensional, steady-state fluid dynamic model of a bubbling fluidized-bed coal gasifier is presented
considering two phase theory of fluidization. The effect of mass flow rate of the fluidizing medium and reactor diameter
on the hydrodynamic characteristics of both the bubble and emulsion phases in the gasifier bed are studied for Geldart
group B particles. Bubble diameter, bubble velocity and bubble area fraction are evaluated for the bubble phase while,
gas velocity and porosity are studied in the emulsion phase, along the height of the bed. Finally inter-phase gas
exchange rate from the emulsion phase to bubble phase is calculated under different operating conditions.

In this study, exergy analysis of an integrated gasification combined cycle (IGCC) operating with 7 different types of low rank Turkish lignite was performed. The purpose was to determine and compare the performance of each type of lignite in the same gasifier. Exergy destruction of each component and exergetic performance of the overall plant was also investigated. In addition, CO2 emissions of each type of lignite were calculated. The results showed that Yeniköy lignite had the best performance among the different types of lignite, with 491 MW net power and 37.88% net exergy efficiency (without acid gas). It also had the minimum amount of CO2 emission at 726 kg/MWh. Therefore, Yeniköy lignite was chosen as a case study fuel and a detailed exergy analysis of its components was applied. The results showed that the major exergy destructions took place in the gasifier and the combustion chamber at 46.15% and 22.74%, respectively.

In this work, the contact economizer system is used to recover low potential heat from the gas turbine exhaust (flue gas) stream of a heat integrated IGCC plant adopted from previous studies. Recovery of this heat was demonstrated to be capable of further increasing the thermal efficiency of the plant. Application of Mickley's graphical technique for dehumidification in a contact economizer system following a slightly different procedure that allows calculation of the exact ratio between the liquid-phase heat transfer coefficient and gas-phase mass transfer coefficient demonstrated a possible increase in thermal efficiency from 54% to 55%. This method however is incapable of obtaining the optimum thermal efficiency due to the monotonous relationship between the boiler feed water temperature and the thermal efficiency of the plant.

ISAB Energy Services (IES) is a Service Company, owned by ERG, an Italian independent multi-energy company, and International Power Mitsui, who operates in Priolo Gargallo (Sicily-Italy) the Integrated Gasification Combined Cycle Complex on behalf of the owners of the plant.

The British Gas/Lurgi  (BGL) is a counter- current fixed bed solid fuel gasification process.  After testing a broad variety of coals, the BGL- gasification process was commercially used for the gasification of a mixture of coal, lignites and various grades of municipal waste. The BGL gasifier has an inner diameter of 3.6 m and operates at a pressure of 24 bar. The gasification agent is a mixture of steam and oxygen.  The gasifier capacity ranges between 30-80  ton/h depending on the feedstock composition. Fixed bed gasifiers require fuel in lump form (20 – 80 mm)  to  allow  the  counter-current  operation  of  descending  fuel  and  rising  gasification  product gases.  To  minimize  fines  loading,  some  agglomeration  of  the  feed  by  briquetting,  pelletizing  or other methods may be required. The BGL gasification facility incorporates significant changes as compared to the BGL demonstration plant (British Gas Development Centre, Westfield, UK), such as: scale-up of the inner reactor diameter from 2.3 m to 3.6 m, and the gasification of waste material in addition to coal and lignites. The BGL unit was commissioned when the first trial run period started at the German Schwarze Pumpe facility.
This  paper  presents  an  overview  on  Envirotherm`s  coal  gasification  technology,  applying  the proprietary  BGL  slagging  pressure  gasification  process integreted with Coal to Liquids (CTL) Project. And also this paper has been prepared for the plant project of methanol and energy production at the Kütahya Tuncbilek Zone / Turkey. In order to describe design criteria, equipments and feasibility of the plant needed for electricity and methanol production from the obtained syngas by gasification of Tunçbilek lignites using by the BGL-CTL (British Gas/Lurgi-Coal to Liquids) Technology also has been described in this study.

• Inclusion of 15% N 2 in CO 2 stream increases CH 4 recovery by at least 25%. • CH 4 is first replaced by CO 2 in large cages followed by N 2 in small cages. • N 2 is selectively captured in hydrate cages below 12 °C. • Higher sequestration potential observed at lower heating rates.

A B S T R A C T Thermal stimulation was combined with an injection of a mixture of CO 2 (85%) + N 2 (15%) to investigate efficiency enhancements from pure thermal stimulation and thermal stimulation with CO 2 injection approaches. Tests were performed at initial hydrate saturation of 10% and 300 ml/min CO 2 + N 2 injection rate with three different heating rates of 20, 50 and 100 W. The results indicate that thermal stimulation with CO 2 + N 2 injection is the most efficient method available for methane gas recovery. At 10% Hydrate Saturation (SH) and 100 W heating rate, the number of moles of CH 4 recovered increased from 8.5 to 16 to 20 in the case of thermal stimulation, thermal stimulation with CO 2 exchange and thermal stimulation with CO 2 + N 2 exchange respectively. The experimental results reported here are aligned with model and Raman spectroscopy predictions in terms of replacement mechanism and recovery efficiency, reported in the literature. The results obtained from CO 2 /N 2 composition ratio show that in the exchange process, CO 2 first replaces CH 4 in the large cages of Structure I hydrates followed by N 2 targeting CH 4 in the small cages of Structure I hydrates. This replacement mechanism has been predicted in the literature by Liu et al. (2016) using Molecular Dynamics simulations. It is also found from this work that N 2 is selectively captured in hydrate cages below 12 °C. The values of carbon sequestration index (defined as moles of CO 2 sequestered divided by moles of CH 4 recovered) were 0.32, 0.52 and 0.85 respectively for 100, 50 and 20 W heating tests. The data obtained from our work in terms of gas composition, methane recovery and CO 2 sequestered is consistent with the key findings reported in the literature .