US5348568A — Filtering method of flue gas of a boiler and a fi…

Claim 1

Independent Claim 144 words

A filtering method of flue gas of a boiler employing a filter apparatus integrated with ceramic filters and provided with control means for regenerating the ceramic filters by reverse cleaning, the method comprising the steps of: detecting directly or indirectly, by use of a detecting means, an unburnt component and flue gas accompanying said unburnt component introduced into the filter apparatus when combustion in the boiler is incomplete; opening and closing valves of a compressed gas by a signal transmitted from the control means when flying-over of the unburnt component to the filter apparatus is detected; and performing a reverse cleaning by blowing the compressed gas into spaces of a cleaned gas side of said filter apparatus, wherein said reverse cleaning is frequently performed in intervals shorter than four minutes and continues until the flying-over of the unburnt component decreases to a small quantity.

Claim 2

Dependent Claim 144 words

A filtering method of flue gas of a boiler employing a filter apparatus integrated with ceramic filters and provided with control means for regenerating the ceramic filters by reverse cleaning, the method comprising the steps of: detecting directly or indirectly, by use of a detecting means, an unburnt component and flue gas accompanying said unburnt component introduced into the filter apparatus when combustion in the boiler is incomplete; opening and closing valves of a compressed gas by a signal transmitted from the control means when flying-over of the unburnt component to the filter apparatus is detected; and performing a reverse cleaning by blowing the compressed gas into spaces of a cleaned gas side of said filter apparatus, wherein said reverse cleaning is frequently performed in intervals shorter than four minutes and continues until the flying-over of the unburnt component decreases to a small quantity.

Claim 3

Dependent Claim 30 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects a dust concentration of the flue gas.

Claim 4

Dependent Claim 26 words

The filtering method of flue gas of a boiler according to claim 2, wherein the detecting means for detecting the unburnt component is an optical sensor.

Claim 5

Dependent Claim 46 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects increase of a pressure difference of the ceramic filters or increase of an increasing rate of the pressure difference of the ceramic filters.

Claim 6

Dependent Claim 48 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects increase of a temperature difference between positions of respective ceramic filters or increase of a temperature difference between cleaned gas chambers partitioned by tube sheets.

Claim 7

Dependent Claim 44 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects decrease of oxygen concentration of the flue gas or increase of absolute value of a decreasing rate of the oxygen concentration.

Claim 8

Dependent Claim 42 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects increase of carbon monoxide concentration of the flue gas or increase of increasing rate of the carbon monoxide concentration.

Claim 9

Dependent Claim 31 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects a load increase instruction of the boiler load.

Claim 10

Dependent Claim 45 words

The filtering method of flue gas of a boiler according to claim 1, wherein the detecting means for detecting the unburnt component detects a purge instruction of a fuel charge manifold of the boiler and the reverse cleaning is temporarily performed by compressed nitrogen gas.

Claim 11

Dependent Claim 30 words

The filtering method of flue gas of a boiler according claim 1, wherein the flue gas is a pressurized flue gas emitted from a coal-fired pressurized fluidized bed combustion boiler.

Claim 12

Dependent Claim 29 words

The filtering method of flue gas of a boiler according to claim 10, wherein the flue gas is emitted from a bubbling bed type pressurized fluidized bed combustion boiler.

Claim 13

Dependent Claim 43 words

The filtering method of flue gas of a boiler according to claim 1, wherein blowing down for extracting dust laden gas from a hopper provided at a lower portion of a filter vessel is carried out in parallel with the frequent reverse cleaning.

Claim 14

Dependent Claim 127 words

A filter apparatus for hot gas comprising: ceramic filters incorporated in a vessel; a reverse cleaning means for regenerating the ceramic filters by removing dust trapped by the ceramic filters; a hopper provided at a lower portion of the vessel for collecting the removed dust; a diffuser provided in the vicinity of a gas introducing port of the vessel or at a dust laden gas introducing pipe; and one or more gas passages for communicating an inlet of the diffuser with the hopper; wherein the diffuser converts a dynamic pressure of the dust laden gas to a static pressure and recirculates the dust laden gas to the inlet of the diffuser from the hopper and through said one or more gas passages by utilizing said static pressure.

Claim 15

Dependent Claim 127 words

A filter apparatus for hot gas comprising: ceramic filters incorporated in a vessel; a reverse cleaning means for regenerating the ceramic filters by removing dust trapped by the ceramic filters; a hopper provided at a lower portion of the vessel for collecting the removed dust; a diffuser provided in the vicinity of a gas introducing port of the vessel or at a dust laden gas introducing pipe; and one or more gas passages for communicating an inlet of the diffuser with the hopper; wherein the diffuser converts a dynamic pressure of the dust laden gas to a static pressure and recirculates the dust laden gas to the inlet of the diffuser from the hopper and through said one or more gas passages by utilizing said static pressure.

Claim 16

Dependent Claim 27 words

The filter apparatus for hot gas according to claim 13, wheerein the diffuser is a portion of an ejector having a nozzle at said gas introducing port.

Claim 17

Dependent Claim 30 words

The filter apparatus for hot gas according to claim 13, wherein the vessel is a pressure vessel and the one or more gas passages are provided inside the pressure vessel.

Claim 18

Dependent Claim 89 words

The filter apparatus for hot gas according to claim 13, wherein the ceramic filters comprise a plurality of filter tubes which are open at both ends thereof, an inner portion of the vessel is partitioned by a plurality of approximately horizontal tube sheets, a gas inlet chamber is provided above the top tube sheet, the PG,76 plurality of filter tubes are held by the tube sheets at the respective ends thereof and the dust laden gas flows from top to bottom through inside of the plurality of filter tubes.

Claim 19

Dependent Claim 90 words

The filter apparatus for hot gas according to claim 13, wherein the ceramic filters comprise a plurality of filter tubes each of which is closed at one end thereof, one or more filtration units are provided in the vessel in which a plurality of filter tubes are installed at the top sides or the bottom sides of cleaned gas headers in approximately vertical direction, and the dust laden gas is filtered while flowing down from the top portions of the filtration units along the external sides of the filter tubes.

Claim 20

Dependent Claim 25 words

The filter apparatus for hot gas according to claim 17, wherein the plurality of filtration units are provided in the vessel in the horizontal direction.

Claim 21

Dependent Claim 127 words

A filter apparatus for hot gas, comprising: ceramic filters incorporated in a vessel; reverse cleaning means for regenerating the ceramic filters by reverse cleaning; at least one detecting means for directly or indirectly detecting flue gas accompanied by unburnt component and a flying-over of the unburnt component to the filter apparatus; control means including means for opening and closing valves of a compressed gas in response to a signal transmitted from the control means when the flying-over of the unburnt component is detected to thereby start a frequent reverse cleaning in which compressed gas is blown into a space on a cleaned gas side of the filter apparatus, wherein the frequent reverse cleaning is continued until the flying-over of the unburnt component decreases to a small quantity.

Claim 22

Dependent Claim 127 words

A filter apparatus for hot gas, comprising: ceramic filters incorporated in a vessel; reverse cleaning means for regenerating the ceramic filters by reverse cleaning; at least one detecting means for directly or indirectly detecting flue gas accompanied by unburnt component and a flying-over of the unburnt component to the filter apparatus; control means including means for opening and closing valves of a compressed gas in response to a signal transmitted from the control means when the flying-over of the unburnt component is detected to thereby start a frequent reverse cleaning in which compressed gas is blown into a space on a cleaned gas side of the filter apparatus, wherein the frequent reverse cleaning is continued until the flying-over of the unburnt component decreases to a small quantity.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-09-19	1998-03-21	1998-09-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-09-19	2002-03-21	2002-09-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-09-19	2006-03-21	2006-09-20	$7700.00	Window Closed / Lapsed

Filtering method of flue gas of a boiler and a filter apparatus for hot gas

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