Current requirements concerning the clean combustion technology both in automotive sector and energy industry force to search fuels with small molar concentration of carbon and sulfur. One of the best methods to obtain gaseous fuels is gasification of solid fuels and biomass together with municipal sewage. Dispersion of energy production requires smaller gasifier for local applications. The paper presents various small gasification systems with water-coal mixture and water-biomass mixture both with oxygen (air) and without oxygen. Mathematical modelling together with 13 kinetic chemical reactions enabled to apply them in CFD program. The chemical model is based on surface reaction. Simulation of gasification of different gasifier designs enabled to obtain the mass concentration of chemical compounds on the outlet of the system. The work includes also general flow of the fluid inside gasifier. Increasing of internal turbulence inside the gasification system gives better and quicker gasification process than in the stationary flow about 30%. Additionally, heating of the gasifier walls by electrical system without air gives higher mass ratio of hydrogen (0.1) and carbon monoxide (0.85) at the outlet than in the system with the air. The air consumes some part of the fuel and a lot of carbon dioxide is produced. The paper shows comparison of mass concentration of CO, H2, H2O, H2S, CO2, O2, CH4, tar, C(s) and other chemical compounds in the syngas for solid fuel, biomass and municipal sewage. Computation of different gasification systems enabled to choice the better system to obtain higher concentration of hydrogen in the syngas. Generally, turbulence and internal heating of the water-fuel mixture enables higher concentration of hydrogen in the syngas. Such system will be used in one of polish small enterprise for fuelling of special industrial piston engine. This article is the result of research work carried out in the project financed by polish National Centre of Research and Development