(24b) Application of Hydrocavitation to Production and Combustion of Composite Fuels

1. Introduction
Rational use of non-renewable energy sources is an urgent problem. Disposal of waste from various industries is no less important. Hydrocavitation technology for production of composite fuels based on “classic” hydrocarbons (mazut, diesel fuel) and various types of waste makes it possible to cope with a complex problem. Composite fuels include substandard hydrocarbons: old mazut, tank wash-outs, vat residues, waste of coal preparation plants, etc. The following can be used as moisture-containing additives: biomass, industrial effluents, in particular, phenolic water, spent technological liquids of oil production, sludge from municipal sewage treatment plants, etc. Products of recycling solid household waste, polymers, rubber and other wastes can also be used.
The application of the hydrocavitation activation methodology in the technologies of production and combustion of composite fuels comprehensively solves the energy problem of obtaining cheaper heat and electrical energy, as well as the environmental problem of reducing harmful emissions into the atmosphere during combustion. At the same time recycling and disinfection of wastes added as components to composite fuels take place.
Intensification of physical and chemical processes contributes to the improvement of existing and development of new efficient technologies and equipment for processing and consumption of hydrocarbon energy carriers. Enhancement of functionality and cutting costs of the introduction of new technologies is a goal.

This work objective was to improve the quality and efficiency of physicochemical processes of production and burning of composite fuels, which can be achieved by the use of activation and owing to the methods of mathematical and physical modeling.
The following tasks were set:
– improve mathematical model of flow hydrodynamics in hydrocavitation devices to enhance efficiency of production and combustion of composite fuels;
– develop and produce samples of experimental equipment for studying efficiency of production and combustion of composite fuels using hydrocavitation activation;
– investigate energy and environmental indicators of production and combustion of composite fuels with various types of waste in their composition;
– prove the possibility of introducing various waste products into composition of composite fuels.

Discussion of the results obtained when studying production and combustion of composite fuels
To produce new types of liquid composite fuels with addition of industrial wastes of various origins, application of special technological methods is necessary.
The most important consumer properties of composite fuels include the possibility of their long-term storage (resistance to stratification) and viscosity. To achieve these properties, it is necessary to apply the methodology of hydro-cavitation activation of fuel components using a hydro-cavitation device. Design solutions for the equipment intended for hydrocavitation activation have made it possible to broaden the nomenclature of composite fuels with addition of waste of various origins as fuel components, for example, spent fracking fluid, phenolic wastewater, sludge, solid waste products, etc. [22–26].
Depending on the components being added, respective operating conditions for the hydro-cavitation device were selected to improve the fuel properties.
An example of obtaining a composite fuel with the addition of spent FF to a diesel fuel at various concentrations showed the possibility of rational use of harmful wastes.
For the combustion of composite fuels in which environmentally hazardous wastes of various origins have been introduced, a special burner has been designed. Analysis of the composition of flue gases evolved in the combustion of composite fuels (Table 2) fully complies with environmental standards and requirements.
The technology developed for burning composite fuels solves the ecological problem of recycling industrial waste and the task of obtaining cheaper thermal energy.
The proposed technological approach is universal and can be used for the disposal and neutralization of organic and mineral wastes of various origins using methods of hydrocavitation activation at the stages of production and combustion of composite fuels.

Experimental studies of composite fuel production processes with addition of wastes of oil and gas producing industry
When developing new types of energy resources in a form of composite fuels, much attention is paid to qualitative characteristics of the resulting fuel mixtures for ensuring their use in existing power generating units without significant structural changes in the latter. Stability (resistance to stratification over time) and viscosity are important consumer properties of the composite fuels. Namely, these properties determine the possibility and duration of storage of fuels, their transportation conditions, technologies and methods of their spraying and burning. To ensure specified consumer properties, hydrodynamic cavitation activation of the fuel components is carried out using a hydrocavitation device schematic view of which is shown in Fig. 6.

The paper implements a theoretical-experimental approach to improve the efficiency of applying the methodology of hydro-cavitation activation of physicochemical processes in the technologies of production and combustion of composite fuels.
1. In the research methods have been developed for mathematical and computer simulation of hydrodynamics of viscous incompressible fluid flows in channels of a complex shape using the structural method of R-functions enabling detection of turbulence and cavitation zones in which intensification of physicochemical and heat exchange processes in heterogeneous media takes place. Application of these methods makes it possible to shorten time and improve quality of designing devices for hydrocavitation treatment for liquids.
2. Comprehensive studies into production and burning of composite fuels with the application of methods of activation of physical and chemical processes were carried out. The obtained composite liquid fuels based on “classic” hydrocarbons (mazut, diesel fuel) with the addition of various types of waste ensure compliance with current energy, ecology and consumer related requirements.
3. Experimental research on the production and combustion of composite fuel with the addition of spent fracking liquid of oil and gas wells for intensification of hydrocarbons, which proved the possibility of zero-discharge recycling of industrial waste with a full fired neutralization of organic amines and other harmful chemicals.
4. Industrial pilot studies were conducted on energy efficiency and environmental friendliness of production technology and combustion of composite fuel based on mazut with the addition of sludge from municipal wastewater treatment plants using hydrocavitation activation methodology, which proved the possibility of utilization of industrial and municipal waste of this origin with possible savings of up to 10% of hydrocarbons.
The obtained results allow to state the prospects of using the presented technologies for environmentally safe and energy-efficient disposal of a wide range of moisture-containing effluents and industrial wastes.