Gasification parameters

In addition to the detailed gas composition and gas heating value, the most important thermochemical parameters describing the performance of the conversion process and the quality of the generated gases are introduced in this section. The cold gas efficiency cge i given by Equation (4.12), where Wgas represents the mass flow of dust-free product gas in kg/s and Wcoai is the mass flow of coal in kg/s fed in the overall process. 

To identify the usability of a certain gas for a synthesis, the molar H2/CO ratio is computed as follows  

The parameter r o allows us to assess the gas treatment effort required for a desired synthesis for example, for methanol synthesis, rmoi 2.1 is required. 

Looking at the consumption and performance of the gasification process, the carbon conversion Xc in percent (Equation (4.16)) describes the amoimt of carbon converted to a gaseous product by relating the mass flow of carbon entering the process in the feedstock wc,in in kg/s to the unconverted mass flow of residual carbon me,res, which typically leaves the process in dust or ash streams. 

Regarding consumption, oxygen and steam are the most important streams as they call for noticeable auxiliary power demand and financial effort Their specific consumptions w in m (STP)/kg(waf) and u in kg/kg(wal) are related to the mass flow of water and ash free (waf) coal as given by Equations (4.17) and (4.18). 

---

The exergetic efficiency of the two alternatives is shown in relation to the gasification parameters (pressure, temperature). A downstream waste heat boiler has great exergetic advantages particularly at low and medium gasification pressures. 

An exergetic analysis of coal gasification has already been performed for individual processes (1, 2). This showed that high exergetic losses may occur in the waste heat section of such a plant. In this article, an attempt is made to determine the influence of the chosen concept and the gasification parameters on the exergy balance by systematic investigation. 

Cateni, B. 2007. Effect of feed composition and gasification parameters on producer gas from a pilot scale fluidized bed gasifier. PhD Thesis. Oklahoma State University, Stillwater, OK. 

Parameter Steam reforming (SR) Partial oxidation (POX) Texaco gasification (TG) Water electrolysis... 

Table 10.5 shows the major technoeconomic parameters of the aforementioned gasification processes. 

Two-constant equation of state phase behavior calculations for aqueous mixtures often require the use of temperature dependent binary interaction parameters. The methods used for evaluating these parameters for some of the typical aqueous binary pairs found in coal gasification and related process streams are described. Experimental and predicted phase compositions based on these methods are illustrated for aqueous pairs containing CO2. H2S, NH3, and other gases. 

Table 6.8 Range of the main operating parameters in pyrolysis and steam gasification processes...

Much experience has also been gained which should contribute toward better understanding of the parameters that control effective gasification. 

Ignition Parameters B.N. Kondrikov et al, Ignition and Gasification of Ballistite Powder Under the Effect of Carbon Dioxide Laser Radiation , TrMoskKhimTekhnolInst 83, 67—78 (1974) (Russ) CA 85, 162865 (1976) [Reported is the effect of C02—laser radiation... 

The model does not refer to any particular coal gasification process. However, in. view of the fact that the coal/water ratio is an essential parameter in the following calculations, it is obvious that in these cases it is the Texaco coal gasification process that was used as a basis. 

---