High heating value

Polystyrene has a high heating value, 46,000 kj/kg compared to heating oil, 44,000 kj/kg (46). Thus, incineration for its energy value is another possible appHcation for recovered polystyrene. 

The initial biogas recovered is an MHV gas and is often upgraded to high heat value (HHV) gas when used for blending with natural gas suppHes. The aimual production of HHV gas ia 1987, produced by 11 HHV gasification facihties, was 116 x 10 m of pipehne-quaUty gas, ie, 0.004 EJ (121). This is an iacrease from the 1980 production of 11.3 X 10 m . Another 38 landfill gas recovery plants produced an estimated 218 x 10 m of MHV gas, ie, 0.005 EJ. Additions to production can be expected because of landfill recovery sites that have been identified as suitable for methane recovery. In 1988, there were 51 sites ia preliminary evaluation and 42 sites were proposed as potential sites (121). 

Coal can be converted to gas by several routes (2,6—11), but often a particular process is a combination of options chosen on the basis of the product desired, ie, low, medium, or high heat-value gas. In a very general sense, coal gas is the term appHed to the mixture of gaseous constituents that are produced during the thermal decomposition of coal at temperatures in excess of 500°C (>930°F), often in the absence of oxygen (air) (see Coal CONVERSION PROCESSES, gasification) (3). A soHd residue (coke, char), tars, and other Hquids are also produced in the process ... 

High Heat- Value Gas. High heat-value (high Btu) gas (7) has a heating value usually in excess of 33.5 MJ/m (900 Btu/fT). This is the gaseous fuel that is often referred to as substitute or synthetic natural gas (SNG), or pipeline-quaHty gas. It consists predominantiy of methane and is compatible with natural gas insofar as it may be mixed with, or substituted for, natural gas. 

Any of the medium heat-value gases that consist of carbon monoxide and hydrogen (often called synthesis gas) can be converted to high heat-value gas by methanation (22), a low temperature catalytic process that combines carbon monoxide and hydrogen to form methane and water. 

Gasification technologies for the production of high heat-value gas do not all depend entirely on catalytic methanation, that is, the direct addition of hydrogen to coal under pressure to form methane. 

As in most of the high heat-value processes, the raw gas is in the medium heat-value gas range and can be employed direcdy in that form. Removing the carbon dioxide raises the heating value, but not enough to render the product worthwhile as a high heat-value gas without methanation. 

Regulations require that the incinerator furnace be at normal operating conditions, including furnace temperature, before hazardous wastes are injected. This requires auxiUary fuel burners for furnace preheating. In addition, the burners provide heat when the wastes burned are of low heating value. Auxihary burners are sized for conditions where Hquid wastes are injected without the addition of high heating value wastes. 

Le d Hii. h level/overflow, Low level/empty Heal value High heat value. 1 le, value... 

Net Heat of Combustion (High Heat Value) for Various Liquid and Gaseous Fuels [4]... 

The preceeding discussion was confined mostly to the carbon deposition curves as a function of temperature, pressure, and initial composition. Also of interest, especially for methane synthesis, is the composition and heating value of the equilibrium gas mixture. It is desirable to produce a gas with a high heating value which implies a high concentration of CH4 and low concentrations of the other species. Of particular interest are the concentrations of H2 and CO since these are generally the valuable raw materials. Also, by custom it is desirable to maintain a CO concentration of less than 0.1%. The calculated heating values are reported as is customary in the gas industry on the basis of one cubic foot at 30 in. Hg and 15.6°C (60°F) when saturated with water vapor (II). Furthermore, calculations are made and reported for a C02- and H20-free gas since these components may be removed from the mixture after the final chemical reaction. Concentrations of CH4, CO, and H2 are also reported on a C02 and H20-free basis. 

The use of pyrolysis for the recycling of mixed plastics is discussed and it is shown that fluidised bed pyrolysis is particularly advantageous. It is demonstrated that 25 to 45% of product gas with a high heating value and 30 to 50% of an oil rich in aromatics can be recovered. The oil is found to be comparable with that of a mixture of light benzene and bituminous coal tar. Up to 60% of ethylene and propylene can be produced by using mixed polyolefins as feedstock. It is suggested that, under appropriate conditions, the pyrolysis process could be successful commercially. 23 refs. 

RDF quality is affected by input component, in that, biowaste content accounted for a remarkable parameter. The three parameters - high heating value, water content (WC), and emission factor (EF) - could be better from sample with medium ratio of bio waste to nylon waste (4 1). The higher or lower value of this ratio has not yet given better result. 

MJ/kg high heating value both moisture free)... 

Level High level/overflow Low level/empty Heat Value High heat value Low heat value... 

High heating-value gas (20 to 35 MJ/m3 or 540 to 940 Btu/ft3) can also be used as fuel gas for gas turbines in IGCC applications, for SNG and hydrogen production, for fuel cell feed, and for chemical and fuel synthesis. However, it does not require as much upgrading and methanation to produce SNG. 

The heating value, or calorific value, expressed as kj/kg (Btu/lb), is the heat produced at constant volume bv the complete combustion of a unit quantity of coal in an oxygen-bomt calorimeter under specified conditions (ASTM D 5865-04, ASTM International, op.cit.). The result includes the latent heat of vaporization of the water in the combustion products and is called the gross heating or high heating value (HHV) Qh- And Qh in Btu/lb (x 2.326 = kJ/kjy on a dry basis can be approximated by a formula developed by the Institute of Gas Technology ... 

Heterogeneous solid or liquid waste can be homogenized into a high-heating value gaseous stream by pyrolysis. 

A promising and relatively new way to utilize both whole and processed old tyres (Fig. 1) is to recover the energy contained in this waste material. As an energy source, tyres represent an attractive alternative to other fuels due to their high heating value. On average, the... 

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