Coal injectors

The conical coal injector was replaced with a blunt cyclin-der with a single axial jet so the flame could be stabilized at lower swirl numbers, thereby reducing the centrifugal deposition on the furnace walls. The radiation shield between the combustor and heat exchanger was removed to reduce particle losses further. The increased radiative transfer decreased the wall temperature substantially. The later experiments were also carried out at lower fuel-air equivalence ratios, i.e., (J> = 0.57. The combination of increased heat losses and increased dilution with excess air reduced the maximum wall temperature to 990°C for the experiments reported below. 

To overcome this problem a coal injector was designed and constructed. The coal injector was a stainless steel cylinder, 8 inches long, 3 inches outside diameter, and 1.5 inches inside diameter. One side of the cylinder was open, and the other was provided with a 0.25-inch stainless steel female fitting (Figures 2 and 3). A piston, provided with an O ring gasket, was used for the open side of the cylinder and could move back and forth by a mechanical... 

Figure 2. Major parts of coal injector with their measurements...

Figure 3. Coal injector used for solvent extraction...

Figure 18 - Service Life of Oxygen and Coal Injectors...

Pulverized coal is fed directly from a variable speed auger into the high velocity primary air stream which conveys it to the injector at the top of the furnace. The coal and primary air enter the combustor through a single low-velocity axial jet. Secondary combustion air is divided into two flows which enter the combustor coaxial to the primary stream. Part of the flow is introduced through a number of tangential ports to induce swirl which is necessary for flame stabilization. The remainder enters the combustor axially. The two secondary air streams are separately preheated using electrical resistance heaters. 

The air-steam mixture (approx 7 vols of air for 1 vol of steam) is forced into app by means of an injector. The amt of steam used for 1 Lb of coal gasified lies betw 0.3 and 0.5 lb. The vol of gas produced from bituminous coal is about 60 cu ft semibitumitiious yields 30 and lignite 28 cu ft... 

However, conversion from light to heavy fuel cannot be accomplished without regard for the deleterious effect the use of a residual quality or coal-derived fuel oil would have on combustion eflBciency, pollutant emissions, and engine operational costs. That is, the extent of fuel atomization required for eflBcient combustion in gas turbine and similar combustion devices cannot be achieved if a high-viscosity heavy fuel oil is simply substituted for a lighter oil. Furthermore, the required atomization cannot be realized easily by modifying the configuration of the fuel injector because injectors compatible with current or currently... 

CEB will be used for coal and waste combustion, and not primarily for heavy fuel oil. However, the projected large-scale test 7 MW, facility can only use heavy fuel oil. Therefore, this oil was used to test it on a small scale. A small flame tunnel with separate air and liquid fuel injectors was constructed to demonstrate the potential of CEB to recover SO2. Figure 10 shows a photograph of the set-up, with the control panel at the right hand, and the flame tunnel in the middle. The three injection ports for CEB material are visible at the front side. Through the opening in the middle (the nozzle has been removed), the flame from diesel combustion is clearly visible. In all experiments, CEB is sprayed perpendicular to the fuel stream. A portable Mass Spectrometer has been purchased to analyse the exit gases from the flame tunnel experiments on SO2. 

Supercritical fluid extraction coupled to SFC has been used for the extraction, separation and identification of PAHs from coal. The supercritical extract was expanded with the aid of a frit restrictor accommodated in the sample cavity of a cooled micro-injector, the analytes being deposited by condensation while CO, was sent to waste through a vent valve. Subsequently, the loop contents were connected on-line to the mobile phase of the capillary chromatograph. The extracted analytes were detected by off-line FTIR spectroscopy following collection on a KBr disc and evaporation of the solvent [104]. 

ECUST. 2005. Multi-injector coal water slurry gasification, http //icct.ecust.edu.cn/download/cwsg. pdf (accessed September 16, 2009). 

The feeder and injector produced a thin pencil-like p.c. stream which passed down through the hot zone. The total combustion air supplied was approximately 3 liters/min for the bituminous coals, giving between 10 and 25 percent excess air for p.c. feed rates of 0.24 to 0.28 g/min. The flow and heat transfer conditions were modeled using the methods described by Pigford (16) for conditions of superimposed natural and forced convection at very low mass flow rates. Particle residence times were calculated by summing the centerline gas velocity and terminal velocity using Stokes s law (17). The error introduced using this method should never have exceeded 10 percent, even when pyrite was tested and particle Reynold s numbers approached one. The residence times thus calculated were found to be between one and two seconds. 

These two simple conversions will cover a large part of the stationary equipment. Gas fired home furnaces, water heaters, and stoves will all be handled in this simple manner at low cost. Coal and oil fired equipment will be less simple to convert. It will require the purchase of a low cost gas burner to replace the coal grates and oil injectors. Examples of industrial processes that can be converted in this simple manner include power plants, steel making, glass making, chemical processes, ore refining, and steam for heating. 

Since the initial introduction of laser diffraction instrumentation in the 1970s, many different applications to panicle si/e aniilysis have been reported. Ihese have included measurements of si/e distributions of radioactive tracer particles, ink particles used in photocopy machines, zirconia fibers, alumina particles, droplets from electronic fuel injectors, crystal growth particles, coal powders, cosmetics, soils, resins, pharmaceuticals, metal catalysts, electronic materials, phoiugraphic emulsions, organic pigments, and ceramics. About a dozen instrument companies now produce LALLS instruments. Some I.AI.LS instruments have become popular as detectors for size-exclusion chromatography. 

In Situ Analysis in a Furnace Successful in situ measurement of coal pyrolysis have recently been made (24, 25)> In one application (24), small samples of coal were rapidly injected into a preheated zone which is traversed by the IR beam With this apparatus spectra have been obtained for gases at temperatures up to lOOO C In the second application a gas stream of predetermined composition is heated during transit through a bed of alumina chips maintained at furnace temperature The gas stream then enters a test section, maintained at the same temperature, where coal is introduced through a water cooled injector. After a variable residence time the reacting stream crosses the FT-IR beam and is quenched in a water cooled collector FT-IR spectra have been obtained at temperatures up to 1200 0 The input gas stream and effluent stream can also be analyzed by routing the stream through an infrared cell The spectra presented in Fig 22 were of the effluent gas in the external cell ... 

As the coal is crushed by the rolling action, the hot air dries it and blows the usable fine coal powder out to be used as fuel. The powdered coal from the pulverizer is directly blown to a burner in the boiler in which the powdered coal is mixed in the air suspension with additional pre-heated combustion air and forces it out of a nozzle similar in action to fuel being atomized by a fuel injector in modern cars. Under operating conditions, there is enough heat in the combustion zone to ignite all the incoming fuel. 

FGD materials Derived from a variety of processes used to control sulfur emissions from boiler stacks. These systems include wet scrubbers, spray dry scrubbers, sorbent injectors, and a combined sulfur oxide (SOx) and nitrogen oxide (NOx) process. Sorbents include lime, limestone, sodium-based compounds, and high-calcium coal fly ash. 

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