US4907962A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low NOx burner
Assignee: Hitachi Ltd
•
Filing: 1987-05-26
•
Granted: 1990-03-13
•
Expires: 2007-05-26
Abstract
Abstract A low NOx burner comprises a pulverized coal nozzle for injecting a flow of a mixture of pulverized coal with primary air, a secondary air nozzle arranged externally of and coaxially with the pulverized coal nozzle, a tertiary air nozzle arranged externally of the secondary air nozzle and disposed coaxially with the pulverized coal nozzle, and a swirl flow generator for injecting secondary air and tertiary air as a respective swirl flow. Between the secondary air nozzle and the tertiary air nozzle, there is provided a spacer having such a thickness as to delay the mixing of the secondary air and the tertiary air and to form a swirl flow between the secondary air and the tertiary air.
Inventors
- 👤 Shigeru Azuhata
- 👤 Kiyoshi Narato
- 👤 Hironobu Kobayashi
- 👤 Kenichi Sohma
- 👤 Tooru Inada
- 👤 Norio Arashi
- 👤 Hiroshi Miyadera
- 👤 Masao Masutani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:24
CPC Classifications
F; F23; F23D; F23D1/00; F23D1/02; F23C; F23C7/00; F23C7/002; F23C7/004
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
217 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal and primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage with an outer peripheral wall extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage and having a thickness sufficient for forming a recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said pulverized coal passage; and flame holder means provided on a free end of said pulverized coal passage defining means for forming a swirl flow between said flow of the mixture of the pulverized coal and the primary air and a flow of said secondary air.
Claim 2
Dependent Claim
217 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal and primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage with an outer peripheral wall extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage and having a thickness sufficient for forming a recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said pulverized coal passage; and flame holder means provided on a free end of said pulverized coal passage defining means for forming a swirl flow between said flow of the mixture of the pulverized coal and the primary air and a flow of said secondary air.
Claim 3
Dependent Claim
30 words
A low NOx burner according to claim 1, wherein said tertiary air passage includes an extension comprising a block projecting axially across a free end of said secondary air passage.
Claim 4
Dependent Claim
193 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal and primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage with at least a portion of an outer peripheral wall of said tertiary air passage extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage and having a thickness sufficient for recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said pulverized coal passage; and a gaseous fuel nozzle disposed in said spacer means.
Claim 5
Dependent Claim
193 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal and primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage with at least a portion of an outer peripheral wall of said tertiary air passage extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage and having a thickness sufficient for recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said pulverized coal passage; and a gaseous fuel nozzle disposed in said spacer means.
Claim 6
Dependent Claim
30 words
A low NOx burner according to claim 3, wherein said tertiary air passage includes an extension comprising a block projecting axially across a free end of said secondary air passage.
Claim 7
Dependent Claim
181 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said means for defining a secondary air passage and said means for defining a tertiary air passage defining spacer means having a thickness sufficient to delay the mixing of said secondary air with said tertiary air and to form a swirl flow between said secondary air and said tertiary air; flame holder means provided on a free end of said pulverized coal passage defining means for forming a swirl flow between said flow of the mixture of the pulverized coal with the primary air and a flow of said secondary air; and a gaseous fuel nozzle disposed in said spacer means.
Claim 8
Dependent Claim
181 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; said means for defining a secondary air passage and said means for defining a tertiary air passage defining spacer means having a thickness sufficient to delay the mixing of said secondary air with said tertiary air and to form a swirl flow between said secondary air and said tertiary air; flame holder means provided on a free end of said pulverized coal passage defining means for forming a swirl flow between said flow of the mixture of the pulverized coal with the primary air and a flow of said secondary air; and a gaseous fuel nozzle disposed in said spacer means.
Claim 9
Dependent Claim
30 words
A low NOx burner according to claim 5, wherein said tertiary air passage includes an extension comprising a block projecting axially across a free end of said secondary air passage.
Claim 10
Dependent Claim
261 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage, said tertiary air passage defining means including an extension projecting axially across free ends of said pulverized coal passage and said secondary air passage and having an outer peripheral wall extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; and said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage for forming a recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with the outer peripheral surface extending parallel to said pulverized coal passage; wherein said pulverized coal passage has a cylindrical injecting outlet, said secondary air passage has a secondary air injecting outlet defined by said spacer means in the form of a polygon surrounding said injecting outlet of the pulverized coal passage and a polygonal flared end surface in proximity to the outlet of said secondary air passage, said tertiary air passage having a cylindrical tertiary air injecting outlet surrounding said secondary air injecting outlet.
Claim 11
Dependent Claim
261 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage, said tertiary air passage defining means including an extension projecting axially across free ends of said pulverized coal passage and said secondary air passage and having an outer peripheral wall extending parallel to said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; and said secondary air passage defining means and said tertiary air passage defining means including spacer means disposed to project between said secondary air passage and said tertiary air passage for forming a recirculation flow between said secondary air and said tertiary air at a location adjacent to said spacer means which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with the outer peripheral surface extending parallel to said pulverized coal passage; wherein said pulverized coal passage has a cylindrical injecting outlet, said secondary air passage has a secondary air injecting outlet defined by said spacer means in the form of a polygon surrounding said injecting outlet of the pulverized coal passage and a polygonal flared end surface in proximity to the outlet of said secondary air passage, said tertiary air passage having a cylindrical tertiary air injecting outlet surrounding said secondary air injecting outlet.
Claim 12
Dependent Claim
40 words
A low NOx burner according to claim 7, wherein a plurality of projections are arranged on an outer periphery of the said injecting outlet of the pulverized coal passage at positions corresponding to apexes of the polygonal flared end surface.
Claim 13
Dependent Claim
45 words
A low NOx burner according to claim 4, wherein walls define outlets of said secondary air passage and said tertiary air passage and comprise refractory material, said extension of the tertiary air passage being positioned to project beyond said outlet of the secondary air passage.
Claim 14
Dependent Claim
196 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; and said pulverized air passage defining means and said secondary air passage defining means together including spacer means disposed between said secondary air passage and said tertiary air passage and having a thickness sufficient to delay the mixing of said secondary air with said tertiary air and to form a swirl flow between said secondary air and said tertiary air wherein said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 15
Dependent Claim
196 words
A low NOx burner comprising: means for defining a pulverized coal passage for injecting a flow of a mixture of pulverized coal with primary air; means for defining a secondary air passage arranged externally of and coaxially with said pulverized coal passage; means for defining a tertiary air passage arranged externally of said secondary air passage and disposed coaxially with said pulverized coal passage; swirl flow generator means for injecting secondary air and tertiary air as a respective swirl flow; and said pulverized air passage defining means and said secondary air passage defining means together including spacer means disposed between said secondary air passage and said tertiary air passage and having a thickness sufficient to delay the mixing of said secondary air with said tertiary air and to form a swirl flow between said secondary air and said tertiary air wherein said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 16
Dependent Claim
64 words
A low NOx burner according to claim 1, wherein said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 17
Dependent Claim
64 words
A low NOx burner according to claim 3, wherein said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 18
Dependent Claim
64 words
A low NOx burner according to claim 5, wherein said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 19
Dependent Claim
63 words
A low NOx burner according to claim 7, said spacer means has a projecting end face in a plane perpendicular to axes of said pulverized coal passage and said tertiary air passage and provides a space on a downstream side of said projecting end face in which recirculation flow is generated to delay a mixing of the tertiary air with the primary air.
Claim 20
Dependent Claim
259 words
A low NOx combustor comprising: a primary air passage through flow of a mixture of a primary air with pulverized coal is injected into a combustion chamber of said burner; means forming a secondary air passage disposed radially outwards of said primary air passage, through which secondary air is injected into said chamber and a tertiary air passage disposed radially outwards of said secondary air passage, through which tertiary air is injected into said chamber, an axis of said tertiary air passage being parallel at a projection end portion thereof with an axis of said primary air passage, so that primary air and said tertiary air are projected into said chamber in the same direction; a swirl flow generator disposed in said secondary air passage for generating swirl flow in an injected secondary air flow and for directing it towards an injected tertiary air flow; and said means forming the secondary air passage and the tertiary air passage includes a spacer disposed to project between said secondary air passage and said tertiary air passage, said spacer extending to a projecting end face thereof, which end face exists in a plane perpendicular to axes of said primary air passage and said tertiary air passage, and said spacer providing a space in a downstream side of said projecting end face, in which recirculation flow is generated, at a location adjacent to said spacer which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said primary air passage.
Claim 21
Dependent Claim
259 words
A low NOx combustor comprising: a primary air passage through flow of a mixture of a primary air with pulverized coal is injected into a combustion chamber of said burner; means forming a secondary air passage disposed radially outwards of said primary air passage, through which secondary air is injected into said chamber and a tertiary air passage disposed radially outwards of said secondary air passage, through which tertiary air is injected into said chamber, an axis of said tertiary air passage being parallel at a projection end portion thereof with an axis of said primary air passage, so that primary air and said tertiary air are projected into said chamber in the same direction; a swirl flow generator disposed in said secondary air passage for generating swirl flow in an injected secondary air flow and for directing it towards an injected tertiary air flow; and said means forming the secondary air passage and the tertiary air passage includes a spacer disposed to project between said secondary air passage and said tertiary air passage, said spacer extending to a projecting end face thereof, which end face exists in a plane perpendicular to axes of said primary air passage and said tertiary air passage, and said spacer providing a space in a downstream side of said projecting end face, in which recirculation flow is generated, at a location adjacent to said spacer which has an outer peripheral surface constituting an inner peripheral wall of said tertiary air passage with said outer peripheral surface extending parallel to said primary air passage.
Claim 22
Dependent Claim
28 words
A low NOx burner according to claim 15, wherein a swirl flow generator is arranged in said tertiary air passage to inject the tertiary air as swirl flow.
Claim 23
Dependent Claim
31 words
A low NOx burner according to claim 15, wherein said tertiary air passage includes an extension constituted by a block projecting axially across a free end of said secondary air passage.
Claim 24
Dependent Claim
33 words
A low NOx burner according to claim 17, wherein said passage extension of the tertiary air passage is flared outwardly from a position corresponding to the free end of the secondary air passage.
References Cited (Backward Citations)
US3746499A
Cited
DE3106824A1
Cited
US4381718A
Cited
US4474120A
Cited
US4412810A
Cited
DE3125901A1
Cited
DD212305A1
Cited
EP0160146A2
Cited
US4620571A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |