Heat exchange – Regenerator
Reexamination Certificate
1999-07-06
2002-12-03
Atkinson, Christopher (Department: 3743)
Heat exchange
Regenerator
C165S010000, C431S215000, C431S011000, C432S181000, C432S180000
Reexamination Certificate
active
06488076
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to heating apparatus and heating method for supply of gaseous fluid, and more particularly, to such apparatus and method in which a relatively low temperature gaseous fluid is heated to a high temperature and a heated supply flow at a high temperature is fed to an equipment, such as a combustion furnace or a combustion equipment to be supplied with high temperature gaseous fluid.
BACKGROUND OF THE INVENTION
A variety of combustion furnaces or combustion equipments, such as waste incinerator, waste gasification melting furnace, boiler, waste heat recovery boiler, heating furnace, and coal gasification furnace, are practically used in any kind of facilities, e.g., public facility, power generation plant, chemical plant or the like. In general, such a combustion furnace or combustion equipment is provided with a gaseous fluid feeding device for feeding combustion air to a combustion area of the furnace, and the feeding device includes heating means, such as a heat exchanger utilizing the waste heat of the combustion exhaust gas, preheating apparatus or pre-combustor for preheating or causing pre-combustion of combustion air. The heating means heats or preheats intake air or combustion air and feed a high temperature air flow or preheated air flow to a combustion means or firing means such as a burner.
FIG. 34
is a schematic flow diagram generally illustrating an arrangement of a waste gasfication melting furnace provided with such heating means.
A furnace
6
constituting a waste gasfication melting furnace is connected to an intake system with a forced draft fan
102
and a heating device
101
, and an exhaust system
7
including a cooling device
71
, a flue gas treatment system
72
and a stack
73
. The system
7
is, in general, equipped with a series of exhaust gas treatment means, such as a dust collector and a exhaust gas denitration device. In the furnace
6
, a melting furnace region
60
with a molten waste fluidized zone
61
in its bottom part, and an upper secondary combustion region
62
above the region
60
.
The furnace
6
has a waste inlet opening
63
for charging waste into the region
60
and a secondary material inlet opening
64
for supplying supplementary materials and fuel thereto, the opening
63
being connected to conveying means
66
through a shute
65
and a feeder (not shown) and the opening
64
being connected to a supplementary material feeder (not shown) by a conveyor
67
.
In the region
60
, a plurality of burner throats
50
,
51
,
52
are provided below the openings
63
and the conveyor
67
. The primary throat
50
in the zone
61
is joined to a heating device
101
through the preheated air supply line HA. Pre-combustion or primary combustion of intake air induced through an inlet
103
and the fan
102
is carried out in the device
101
, which feeds high temperature preheated combustion air to the throat
50
through the line HA.
Combustion apparatus provided with such kinds of air heating apparatus permits the oxygen density or excess air ratio of the preheated air to decrease, owing to the pre-combustion or primary combustion. In order to compensate for the reduction of the oxygen density and to ensure a desired combustion reaction in the furnace, the heating device
101
is provided with an oxygen supply line
104
joined to the line HA. The line
104
is connected to an oxygen source
105
having oxygen cylinders, which adds a predetermined flow rate of oxygen (O
2
) to the preheated air flow through the line HA.
Provision of an oxygen feeder, however, results in an increase of initial construction costs for the furnace or combustion equipment, as well as complication of maintenance of the system. Further, such an expensive oxygen cylinder or the like has to be periodically supplied to the oxygen feeder. Thus, since routine maintenance is necessitated for the oxygen feeder, costs for running and maintaining the system is increased. This is undesirable for practical use in long years.
Research and development as regards a variety of coal firing apparatus, Such as coal fired power generation boiler, pulverized coal firing boiler and coal gasification system, and various types of coal fired combined cycle power generation systems, such as AFBC, PFBC or pressurized CPC, are widely conducted in recent years in response to political or social requirements. In general, these kinds of coal fired systems or equipments are provided with heating devices, such as a heat exchanger using waste heat of combustion exhaust gas, which heat or preheat combustion air of ambient atmosphere to an appropriate temperature and feed the preheated air to combustion means such as a burner for pulverized coal.
Various types of coal fired devices are known, e.g., stoker combustion type, pulverized coal fired type, fluidized bed type and so forth. In general, the pulverized coal fired type of boiler is preferably adopted as a coal fired boiler in with a large capacity, such as a boiler of power generation station, since such type of boiler presents relatively good response and controllability as to variation of load and effects a desirable combustion efficiency.
In such a pulverized coal fired boiler, coal particles are carried with primary air into a combustion area and rapidly heated by a burner for pulverized coal. As combustion exhaust gas of the boiler contains a relatively large amount of fuel NOx, thermal NOx, sulfur and smoke dust (dust, fly ash), an exhaust system is generally equipped with a series of desulfurizer, denitration device, and electrostatic precipitator (ESP) and so forth.
FIG. 35
is a schematic flow diagram illustrating such a coal fired system.
A coal fired power generation boiler plant comprises a burner for pulverized coal
120
and a pulverized coal fired boiler
110
, and the burner
120
is connected with a pulverized coal feeding line CS and a secondary air feeding line CA. The line CA is connected to a forced draft fan
121
through a heating section
181
of a rotary air-preheater APH for heating the secondary air to an order of 300° C. The fan
121
feeds intake air from an air intake port
122
and an air intake line OA to the preheater APH and the air preheated thereby is fed to the burner
120
through the line CA. The pulverized coal and air mixed in the burner
120
fires in a combustion area
150
of the boiler
110
to heat superheater
151
, reheater
152
and economizer
153
in the area
150
, and combustion gas is exhausted through an exhaust gas line E
11
. The exhaust system including lines E
11
to E
20
is equipped with exhaust treatment devices wherein electrostatic precipitator (ESP)
171
, ammonia injector
172
connected to an ammonia source (not shown), selective catalytic reduction device
173
with catalyst units, heat accumulating section
174
of a rotary air preheater APH for heat recovery, forced induce fan
175
, heat accumulating section
176
of a gas-gas heater GGH, booster fan
177
, desulfurizer
178
, heat emission section
179
of the gas-gas heater GGH, and stack
180
arranged in series.
A high-cycle regenerative combustion system which is capable of preheating such a supply flow of air to the combustion equipment is disclosed in Japanese patent application No. 5-6911 (Japanese patent laid-open publication No. 6-213585) of the present applicant. This system developed by the present applicant includes a regenerator of honeycomb structure with a number of narrow channels or fluid passages which exhibits a high temperature effectiveness and a high volumetric efficiency. High temperature combustion exhaust gas and low temperature supply fluid flow alternately passes through the regenerator, so that the supply flow is heated to a high temperature above 800° C. by heat exchange with the exhaust gas through the regenerator.
However, in this kind of system, high temperature combustion exhaust gas effluent immediately after a combustion step has to be introduced into the regenerator, since the high temperature gas possessing sensible
Yasuda Tsutomu
Yoshikawa Kunio
Atkinson Christopher
Griffin & Szipl, P.C.
Nippon Furnace Kogyo Kaisha Ltd.
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