Primary combustion chamber

Fig. 15.4 shows a schematic representation of a nozzle throat area controller used in a VFDR. The mass flow rate from the nozzle attached to the primary combustion chamber (gas generator) to the secondary combustion chamber (ramburner) is changed by inserting a pintle. The high-temperature gas produced in the gas generator flows into the ramburner through the pintled nozzle. The pintle inserted into the nozzle moves forward and backward in order to alter the nozzle throat area. As the nozzle throat area is made small, the mass flow rate increases according to the concept described above. The fuel-flow rate becomes throttable by the pintled nozzle. 

PCC primary combustion chamber SCC secondary combustion chamber (after burner) Fig. 3 Automatic wood firing as experimental biomass furnace... 

In the section between the primary combustion chamber (PCC) and the heat exchanger, four different types of SCC were installed. Their RTDs should be close to those of PSR, PFR, and an intermediate type. Two examples of the SCC investigated are shown in Figure 4. 

The primary air reduction is limited by the primary combustion chamber volume. A lower primary air input causes a lower reaction velocity in the solid phase... 

OEC has been used in several different types of incineration applications to overcome thermal limitations in the process.2 One example is a fixed rotary incinerator where kiln instabilities were produced by variations in the incoming waste, which was sometimes cold and wet. The existing combustion system in the primary combustion chamber (PCC) was unable to handle these transient variations. 02 was injected into the kiln through a lance. The 02 flow was automatically controlled, based on feedback from the temperature at the exit. This improved the kiln stability. It also improved the refractory life in the afterburner due to the more uniform temperature profile in the overall system. In general, OEC can be used to increase incinerator throughput of low-heating-value waste materials. 

Oxygen injection is planned to be used on two incinerators being designed for Duisburg, Germany to be commissioned in 1997.21 Between 7000 to 14,000 ft3/h (200 to 400 m3/h) of oxygen will be injected into the primary combustion chambers of the incinerators to reduce the fuel consumption in the secondary combustion chambers. An added benefit will be a reduction in the size of the gas-handling system. 

In addition to APCD, metal emissions from waste combustors can be minimized by 1) limiting the metal content of the waste feed via source control 2) designing and operating the combustion process to minimize metal vaporization and 3) designing and operating the primary combustion chamber to minimize fly-ash carryover. From a practical standpoint, the second method is likely to be the most difficult to implement because the objective of the incineration process is to burn all the combustible waste completely and avoid PIC formation, both of which require the use of high temperatures. Therefore, the most-reliable methods of limiting metal emissions are source control and efficient use of APCD. 

Secondary combustion chamber Primary combustion chamber... 

Low enough combustion temperature to protect the flow rate control valve from heat and high enough to ignite the fuel-rich gas when air is mixed in the secondary combustion chamber the ideal combustion temperature in the primary combustion chamber is approximately 1400 K. 

The rotary kiln incinerator is used primarily to treat explosives-contaminated soils. In rotary kiln incineration, soils are fed into a primary combustion chamber, or rotary kiln, where organic constituents are destroyed. The temperature of gases in the primary chamber ranges from 800° to 1200°F, and the temperature of soils ranges from 600° to 800°F. Retention time in the primary chamber, which is varied by changing the rotation speed of the kiln, is approximately 30 minutes. 

Slag cyclone The primary combustion chamber for a cyclone-fired boiler. Ash from the coal melts in the cyclone and is removed as a slag. 

Rotary kiln (about 40% of U.S. hazardous-waste incinerator capacity) in which the primary combustion chamber is a rotating cylinder lined with refractory materials, and an afterburner downstream from the kiln to complete destruction of the wastes... 

Incinerators used for the disposal of municipal waste rely heavily on various monolithic linings. In the primary combustion chamber, the entrance section is lined with an abrasion-resistant castable. The main section is usually lined with a high-alumina plastic gurmed material, which is backed with an insulating castable. The ducting that connects the primary and secondary combustion chambers is lined with a dense castable material, and so is the secondary chamber. The ducting that connects the dust collectors to the stack is made from an acid-resistant castable. 

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