Continuous combustion systems

Equation (4) states that, to quantify the combustion efficiency, the volume fractions of carbon monoxide and the total hydrocarbon (methane equivalents), the mass flow and the stoichiometry of conversion gas, and the volume flows of primary and secondary air need to be measured. The concept of combustion efficiency is a function of emissions, air dilution, and type of fuel. This concept can be applied to any type of continuous combustion system and any type of fuel. 

In the utilization of synthetic fuels, the key issues are impact on performance, equipment integrity, and emission characteristics of combustion hardware. Emissions of oxides of nitrogen and soot are the most actively researched emission problems for continuous combustion systems, which range from burners to gas turbine combustors. 

R. C. "Fundamental Characterization of Alternate Fuel Effects in Continuous Combustion Systems" D0E/ET/11313-1, 1981, DOE. 

Blazowski, W. S. Edelman, R. B. Harsha, P. T. "Fundamental Characterization of Alternate Fuel Effects in Continuous Combustion Systems", Summary Technical Progress Report for the period 15 August 1977 - 14 August 1978 under Department of Energy Contract EC-77-C-03-1543, September, 1978. 

Numerous studies on a variety of pulse combustor designs have demonstrated that a pulse combustor can offer the following advantages over the conventional (i.e., continuous) combustion systems [25-27] ... 

Wood waste Particulates, smoke, and combustion Continuous-feed systems operation at... 

Examples of novel engine and transmission technologies are homogeneous combustion compression ignition (HCCI), combined combustion system (CCS), combined autoignition (CAI) and continuously variable transmission (CVT). 

According to the three-step model, proposed by the authors, a PBCS can be divided into three subsystems, namely a conversion system, combustion system, and boiler system. It is in the conversion system that the thermochemical conversion of the solid fuel takes place. The conversion system can be designed according to several conversion concepts. The conversion concept can be classified with respect to fuel-bed mode (batch and continuous), fuel-bed configuration (countercurrent, cocurrent and crosscurrent), fuel-bed composition (homogeneous and heterogeneous), and fuel-bed movement (fixed, moving and mixed). 

The maximum work output of any thermodynamic system or process can be obtained, if the material in the system or the working fluid in the process is brought into equilibrium with the environment reversibly. The actual work output of a technical process with combustion is much smaller because the combustion is highly irreversible. The work losses in a continuous combustion can be evaluated if the exergy (or available energy) before and after the reaction is calculated. This exergy is described by the equation ... 

Synthetic liquid fuels derived from coal and shale will differ in some characteristics from conventional fuels derived from petroleum. For example, liquid synfuels are expected to contain significantly higher levels of aromatic hydrocarbons, especially for coal-derived fuels, and higher levels of bound nitrogen. These differences can affect the combustion system accepting such fuels in important ways. In continuous combustors, i.e. gas turbines, the increased aromatics content of coal-derived fuels is expected to promote the formation of soot which, in turn, will increase radiation to the combustor liner, raise liner temperature, and possibly result in shortened service life. Deposit formation and the emission of smoke are other potential effects which are cause for concern. Higher nitrogen levels in synfuels are expected to show up as increased emissions of N0X (NO+NO2) An earlier paper presented results of an experimental study on the effect of aromatics and combustor... 

A somewhat more recent approach to electrostatic atomization and charging has been developed for hydrocarbon fuels in various combustion systems (13). This method employs direct charge injection into the continuous stream of hydrocarbon liquid by means of... 

A fuel cell can be thought of as a cold-combustion power source that generates electrical energy directly from (stored) chemical energy. Due to minimal heat transfers, it is unfettered by conversion-efficiency hmitations characteristic of hot-combustion devices. Unlike batteries, but similar to internal combustion engines, a fuel cell is a continuous-flow system in which fuel and oxidant are externally supplied for operation. In a functional hydrogen-fuel cell, H2 gas is introduced through feed plates to the anode compartment. At the same time, but to the cathode in a separate chamber, O2 gas delivered. At the anode, H2 is oxidized to H ... 

Let us now consider continuous flows of premixed combustible gases and address the question of conditions necessary to retain a flame in the system [2]. This question is of practical significance for many power-production devices. To achieve high power densities, gas velocities in combustors exceed flame velocities, and so means must be found to stabilize flames against blowout, a condition at which the flames are transported through the exit of the burner so that combustion ceases. There are two main classes of stabilization techniques, stabilization by fluid streams and stabilization by solid elements. Although other stabilization methods may be envisioned, such as continuous or intermittent deposition of radiant or electrical energy, in the vast majority of practical continuous-flow systems, stabilization is obtained by techniques that fall within one of the two main classes. Stabilization by solid elements will be discussed first then stabilization by fluid streams will be considered. ... 

In virtually all combustion systems using OEC, the fuel and the oxidizer are not mixed until they exit the burner. This, commonly known as a nozzle-mix burner, essentially eliminates the potential for an explosion caused by flashback. If the flame were to flash back toward the burner, it would be extinguished at the burner nozzle. The flame would not continue to travel into the burner as there would no longer be a stoichiometric mixture since the fuel and the oxidizer are separated inside the burner. Therefore, the potential risk of flashback is eliminated by not premixing the fuel and the oxidizer inside the burner. 

---