Fuel dilution for reducing NOx production

Inactive Publication Date: 2007-03-01
AIR PROD & CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009] In various embodiments, the invention relates to a nozzle comprising a nozzle body having an inlet face, an outlet face, and an inlet flow axis passing through the inlet face and the outlet face, and two or more slots extending through the nozzle body from the inlet face to the outlet face, each slot having a slot axis. The slot axis of at least one of the slots is not parallel to the inlet flow

Problems solved by technology

If the nozzle design geometry is not optimized, the nozzle may require much higher fuel and / or oxidant supply pressures or higher average gas velocities to achieve proper mixing in the furnace and yield the required NOx emission levels.
In many processes in the chemical industry, the fuel supply pressure is limited due to upstream or downstream processes.
However, these methods cannot be used in all low NOx burner designs or heating applications because of furnace space and flame envelope considerations.
However, these methods require additional piping and costs associated with transport of flue gas, steam, or other inert gases.
In addition, there is an energy penalty due to the required heating of dilution gases from ambient temperature to the process temperature.

Method used

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  • Fuel dilution for reducing NOx production
  • Fuel dilution for reducing NOx production
  • Fuel dilution for reducing NOx production

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0111] A combustion test furnace utilizing the burner assembly of FIGS. 8 and 9 was operated to compare the performance of the nozzles of FIGS. 1 and 4 with a circular nozzle configuration illustrated in FIGS. 10A, 10B, and 10C. These nozzles may be defined as staging nozzles which deliver secondary fuel to a second stage of combustion, wherein the fuel for the first stage of combustion is provided by fuel 815 via pipe 813 of FIG. 8.

[0112] The test furnace was 6 ft by 6 ft in cross-section and 17 ft long, had a burner firing at one end, and had an outlet for the combustion products at the other end. The outlet was connected to a stack fitted with a damper for furnace pressure control. The interior of the furnace was lined with high-temperature refractory and had water-cooled panels to simulate furnace load. The test burner was fired in the range of 3 to 6 MMBTU / hr using natural gas for the primary fuel and the secondary (staging) fuel. The flow rate of natural gas was varied betwee...

example 2

[0144] In laboratory testing using the combustion device and combustion method in the test furnace described in Example 1, a burner had 10 fuel lances evenly distributed around a circle of 18″ diameter. Of the 10 fuel lances, two fuel lances were combustion devices described above with a mixing conduit, positioned opposite each other in the circle. Eight of the fuel lances had the geometry of the nozzle without a mixing conduit like that shown in FIG. 2 and two of the fuel lances had the geometry of the nozzle with a mixing conduit like that shown in FIG. 15.

[0145] The burner was rated at a firing rate of 8 MMBtu / hr utilizing 644° F. preheated air. In this example, the fluid for diluting the fuel was also a fuel. The fuel was a simulated refinery offgas and contained 18% hydrogen, 44% local natural gas, and 38% ethylene. The fuel index of this simulated refinery offgas was about 1.43. The other fuel simulated PSA offgas and contained 52% carbon dioxide, 18% local natural gas, and 3...

example 3

[0151] Diluted fuel mixtures may be formed by mixing generally nonreacting gases, such as steam, carbon dioxide, flue gas, nitrogen, or other inert gases with a fuel.

[0152] In another experiment, all of the fuel lances in Example 2 were fitted with a mixing conduit and each of the fuel lances had zipper nozzles as described above. Referring to the arrangement illustrated in corresponding FIGS. 12 and 15, in one experiment nitrogen was introduced through conduit portion 21 and natural gas was introduced through conduit portion 23. In another experiment, no nitrogen was introduced.

[0153] The burner was operated at a firing rate of about 5 MMBtu / h using ambient combustion air. The average furnace operating temperature was about 1600° F. and the exhaust gas temperature was about 2000° F. For the case with nitrogen dilution, nitrogen was introduced to the burner with a flow rate of about 10% of the total flow on a weight basis. For the case without nitrogen dilution, NOx was measured a...

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Abstract

A combustion device and combustion method for mixing a fuel and a fluid to form a diluted fuel mixture and passing the diluted fuel mixture through a nozzle. The nozzle comprises a nozzle body having an inlet face, an outlet face, and an inlet flow axis passing through the inlet face and the outlet face, and one or more slots extending through the nozzle body from the inlet face to the outlet face, each slot having a slot axis.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 10 / 713,232, filed Nov. 14, 2003 and also a continuation-in-part of U.S. patent application Ser. No. 10 / 786,281, filed Feb. 25, 2004, which is a Division of U.S. patent application Ser. No. 10 / 353,683, filed Jan. 29, 2003, U.S. Pat. No. 6,866,503, each incorporated herein by reference.BACKGROUND [0002] Nozzles are used in a wide variety of applications to inject one fluid into another fluid and promote efficient mixing of the two fluids. Such applications include, for example, chemical reactor systems, industrial burners in process furnaces, fuel injectors in gas turbine combustors, jet engine exhaust nozzles, fuel injectors in internal combustion engines, and chemical or gas injection in wastewater treatment systems. Industrial burners may be used in heating reformers, process heaters, boilers, ethylene crackers, or other high temperature furnaces. The object...

Claims

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Application Information

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IPC IPC(8): F23C5/00F23M3/04F23M9/00F23C7/00
CPCF23C6/047F23C2201/20F23C2201/301Y02E20/344F23D14/32F23D14/583F23D14/22
InventorJOSHI, MAHENDRA LADHARAMLI, XIANMING JIMMYSLAVEJKOV, ALEKSANDAR GEORGI
OwnerAIR PROD & CHEM INC