Fluid heater with perforated flame holder

Patent metadata

Field	Value
Publication number	US-9885496-B2
Application number	US-201514811758-A
Country	US
Kind code	B2
Filing date	Jul 28, 2015
Priority date	Jul 28, 2014
Publication date	Feb 6, 2018
Grant date	Feb 6, 2018

Abstract

A water heater includes a water tank having an inlet and an outlet, and a flue extending through the tank. A nozzle is positioned near a first end of the flue, arranged so as to emit a fuel stream into the flue, and a flame holder is located within the flue in a position to receive the fuel stream and to hold a flame entirely within the flue.

First claim

What is claimed is:

1. A fluid heater, comprising:
a tank having an inlet and an outlet;
a flue extending through the tank and having first and second ends;
a nozzle positioned and configured to emit a fuel stream into the flue;
a flame holder having a plurality of apertures extending therethrough and configured to hold a flame substantially within the plurality of apertures, the flame holder being located inside the flue, positioned to receive the fuel stream and to hold the flame entirely within the flue; and
a controller configured to control a flow of fuel to the nozzle according to a temperature of a fluid within the tank;
wherein the controller is configured to stop the flow of fuel while the temperature of the fluid exceeds a first temperature threshold;
wherein the controller is configured to admit the flow of fuel while the temperature of the fluid is no greater than the first temperature threshold; and
wherein the controller is configured to transition from stopping the flow of fuel to admitting the flow of fuel when the temperature of the fluid drops from a temperature greater than the first temperature threshold to a temperature no greater than a second temperature threshold, lower than the first temperature threshold.

2. A fluid heater, comprising:
a tank having an inlet and an outlet;
a flue extending through the tank and having first and second ends;
a nozzle positioned and configured to emit a fuel stream into the flue;
a flame holder having a plurality of apertures extending therethrough and configured to hold a flame substantially within the plurality of apertures, the flame holder being located inside the flue, positioned to receive the fuel stream and to hold the flame entirely within the flue; and
a controller configured to control a flow of fuel to the nozzle according to a temperature of a fluid within the tank;
wherein the controller is configured to transition from stopping the flow of fuel to admitting the flow of fuel when the temperature of the fluid drops below a first temperature threshold.

3. The fluid heater of claim 2 , wherein the controller is configured to preheat the flame holder during a transition from stopping the flow of fuel to admitting the flow of fuel.

4. The fluid heater of claim 3 , wherein the controller is configured to preheat the flame holder by holding a preheat flame between the nozzle and the flame holder.

5. The fluid heater of claim 3 , wherein the controller is configured to preheat the flame holder by applying a voltage to an electrical heating element in contact with the flame holder.

6. A fluid heater, comprising:
a tank having an inlet and an outlet;
a flue extending through the tank and having first and second ends;
a nozzle positioned and configured to emit a fuel stream into the flue; and
a flame holder having a plurality of apertures extending therethrough and configured to hold a flame substantially within the plurality of apertures, the flame holder being located inside the flue, positioned to receive the fuel stream and to hold the flame entirely within the flue;
wherein the fluid heater further comprises a water heater comprising:
a combustion tube having a length L, the combustion tube defining an air column on an inside of the tube and a water volume outside of the tube and inside the tank, the tube having an inlet end configured to receive combustion air and an outlet end configured to output combustion products;
wherein the nozzle comprises a hydrocarbon gas nozzle configured to output a hydrocarbon gas stream into the air column inside of the tube;
wherein the flame holder comprises a perforated flame holder disposed in the air column, the perforated flame holder having a body with a thickness t, the body defining an input side aligned to receive the hydrocarbon gas stream and the combustion air, an output side opposite the input side disposed to output the combustion products, and
wherein the apertures comprise a plurality of perforations extending through the thickness t from the input side to the output side, the perforated flame holder being configured to hold a combustion reaction supported by the hydrocarbon gas and the combustion air within the plurality of perforations; and further comprising:
a support structure configured to support the perforated flame holder between the inlet end and the outlet end of the combustion tube at a distance not equal to L/4 from the inlet end of the combustion tube.

7. The fluid heater of claim 6 , wherein the support structure is configured to support the perforated flame holder such that the entire thickness t of the perforated flame holder is between the inlet end and the distance L/4 from the inlet end of the combustion tube.

8. The fluid heater of claim 7 , wherein the support structure is configured to support the perforated flame holder such that a section of the combustion tube at a distance of L/8 or less from the inlet end of the combustion tube passes through the perforated flame holder body between the input side and the output side.

9. The fluid heater of claim 8 , wherein the support structure is configured to support the perforated flame holder such that a section of the combustion tube at a distance of L/16 or less from the inlet end of the combustion tube passes through the perforated flame holder body between the input side and the output side.

10. The fluid heater of claim 6 , wherein the support structure is configured to support the perforated flame holder such that the entire thickness t of the perforated flame holder is between the outlet end of the combustion tube and the distance L/4 from the inlet end of the combustion tube.

11. The fluid heater of claim 10 , wherein the support structure is configured to support the perforated flame holder such that a section of the combustion tube at a distance of L/2 or more from the inlet end of the combustion tube passes through the perforated flame holder body between the input side and the output side.

12. The fluid heater of claim 11 , wherein the support structure is configured to support the perforated flame holder such that a section of the combustion tube at a distance of 3 L/4 or more from the inlet end of the combustion tube passes through the perforated flame holder body between the input side and the output side.

13. The fluid heater of claim 6 , wherein the support structure is configured to support the perforated flame holder between the inlet end and the outlet end of the combustion tube at a distance selected to not produce audible noise.

14. The fluid heater of claim 6 , wherein the support structure further comprises:
a support tube configured to support the perforated flame holder a distance away from an inside wall of the combustion tube.

15. The fluid heater of claim 14 , wherein the support tube is configured to receive infrared radiation from the perforated flame holder and reflect infrared energy to the inside wall of the combustion tube.

16. The fluid heater of claim 14 , wherein the support tube defines an area selected for substantially unidirectional flow of the hydrocarbon fuel, combustion air, and combustion products and an annular area selected to support bidirectional flow of the air column inside the combustion tube.

Assignees

• Clearsign Comb Corp

Inventors

• Karkow Douglas W
• Colannino Joseph
• Wiklof Christopher A

Classifications

• F23D14/64

  with injectors · CPC title

• F23D14/583

  of elongated shape, e.g. slits · CPC title

• F23D14/02

  Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone · CPC title

• F24H9/1836

  using fluid fuel · CPC title

• F24H1/205 Primary

  with furnace tubes · CPC title