CN102927564A

CN102927564A - Method of reducing fly ash carbon content of circulating fluidized bed boiler

Info

Publication number: CN102927564A
Application number: CN2012105092072A
Authority: CN
Inventors: 卢啸风; 王虎; 王泉海; 梅琳; 郭强; 双伟; 潘智
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2012-12-04
Filing date: 2012-12-04
Publication date: 2013-02-13
Anticipated expiration: 2032-12-04
Also published as: CN102927564B

Abstract

The invention discloses a method of reducing fly ash carbon content of a circulating fluidized bed boiler, wherein the method comprises the following steps when the circulating fluidized bed boiler comprises a hearth, a cyclone separator, a vertical pipe and a feedback device: 1) mounting a helical feeder on the upper part of the vertical part, and connecting an oxygen-enriched air generator at the air inlet chamber on the bottom part of the feedback device; and 2) when the circulating fluidized bed boiler operates, the helical feeder conveys the fly ash to the upper part of the vertical part, the fly ash enters the feedback device through the vertical pipe, the coke in the fly ash in the feedback device and the oxygen-enriched air generated by the oxygen-enriched air generator generate an oxygen-enriched combustion reaction, in the reaction, the percent by volume of the oxygen in the oxygen-enriched air is controlled to control the combustion temperature of the fly ash, and the fly ash and the flue gas return to the hearth after the reaction. The method disclosed by the invention can be applied on circulating fluidized bed boilers of burning inferior coal, and the method can greatly increase the combustion reaction speed and standing time of the coke in the fly ash in the high temperature region of the circulating fluidized bed boiler and greatly reduce the fly ash carbon content of the circulating fluidized bed boiler.

Description

A kind of method that reduces the CFBB unburned carbon in flue dust

Technical field

The present invention relates to reduce the technical field of boiler flyash carbon content, relate in particular to a kind of method that reduces the CFBB unburned carbon in flue dust.

Background technology

CFBB has the outstanding advantages such as fuel tolerance is wide, pollutant emission is low and is able to extensive use.But there are the higher problem of unburned carbon in flue dust in burning in circulating fluid bed boiler colm, especially low volatile colm, and unburned carbon in flue dust can reduce boiler efficiency up to 10%～25%, has increased energy loss, and have limited the comprehensive utilization of flying dust.

At present, for the high problem of CFB boiler flyash carbon content, more existing solutions, but referenced patent---difficult combustion fuel with flying dust at the bottom of raise burning in circulating fluid bed boiler method and device (number of patent application is 200310106047.8) and patent---convergent increaser and gray back pump and flyash reburning type CFBC equipment (number of patent application is 200710054674.X), the former burns cinder reinjection to the bottom of burner hearth emulsion zone, the latter is burnt cinder reinjection to the top of emulsion zone, two kinds of methods are all higher because of fluidising air velocity in the stove, be generally 5～7m/s, flying dust is in short reason of the time of staying in furnace high-temperature district, so that CFBB unburned carbon in flue dust reduction amplitude is very limited.

Summary of the invention

The CFBB unburned carbon in flue dust that the present invention is directed to burning inferior coal is higher, adopt existing fly ash refiring technology, flying dust is short in the time of staying in furnace high-temperature district, reduce the very limited defective of amplitude for unburned carbon in flue dust, propose a kind of method that reduces the CFBB unburned carbon in flue dust.

A kind of method that reduces the CFBB unburned carbon in flue dust of the present invention, when CFBB comprised burner hearth, cyclone separator, standpipe and feeding back device, described method step was as follows:

1) in riser upper screw(-type) feeder is installed, the place connects oxygen-enriched air generator in feeding back device bottom air inlet chamber;

2) when CFBB moves, screw(-type) feeder is sent the flying dust of collecting into riser upper, flying dust enters feeding back device through standpipe, the oxygen-enriched air generation oxygen-enriched combusting reaction that coke in feeding back device in the flying dust and oxygen-enriched air generator produce, in the reaction, by regulating the shared percent by volume control flying dust ignition temperature of oxygen in the oxygen-enriched air, after the reaction, flying dust and flue gas return burner hearth, enter the CFBB ash circulatory system, so repeatedly, so that the CFBB unburned carbon in flue dust significantly reduce.

The present invention compared with prior art, have the following advantages and the high-lighting effect: flying dust is in the high temperature ash circulatory system, can be heated rapidly to the coke ignition temperature, then running on lower fluidising air velocity, be generally 0.3～0.5m/s, be in the bed space of bubbling fluidization, coke in the flying dust and oxygen-enriched air generation combustion reaction, increased significantly combustion rate and the time of staying of coke in the flying dust, be conducive to the abundant burning of coke in the flying dust, after the burning, flying dust and flue gas return burner hearth, enter the CFBB ash circulatory system, so repeatedly, the phosphorus content of decrease flying dust is not affecting the crucial operational factor (temperature of CFBB simultaneously, fluidising air velocity) under the condition, realizes the purpose of control flying dust ignition temperature by the shared percent by volume of oxygen in the oxygen-enriched air of regulating the oxygen-enriched air generator generation.

Description of drawings:

Fig. 1 is the structural representation of the embodiment of the invention 1

Fig. 2 is the structural representation of the embodiment of the invention 2

Fig. 3 is the structural representation of the embodiment of the invention 3

Fig. 4 is the structural representation of feeding back device of the present invention

Fig. 5 is the structural representation of flying dust bubbling fluidized bed of the present invention

Fig. 6 is the structural representation of external bed of the present invention

Among the figure: 1 is burner hearth; 2 is cyclone separator; 3 is standpipe; 4 is feeding back device; 4-1 is inlet air plenum; 4-2 is temperature element; 5 is screw(-type) feeder; 6 is external bed; 6-1 is inlet air plenum; 6-2 is cone valve; 6-3 is feed pipe; 7 is the flying dust bubbling fluidized bed; 7-1 is inlet air plenum; 7-2 is cone valve; 7-3 is feed pipe; 7-4 is temperature element; 8 is oxygen-enriched air generator.

The specific embodiment:

Be described further as follows below in conjunction with Figure of description and embodiment to method of the present invention.

Embodiment 1

As shown in Figure 1, the CFBB of the present embodiment comprises burner hearth 1, cyclone separator 2, standpipe 3 and feeding back device 4, and its step of method that the present embodiment a kind of reduces the CFBB unburned carbon in flue dust is as follows:

1) in distance standpipe 3 tops 500mm～2000mm place level screw(-type) feeder 5 is installed, according to long-term field trial and experience, 3 top 500mm are larger with interior space negative pressure at the distance standpipe, the flying dust of sending into standpipe 3 can't enter the Circulating Fluidized Bed Ash circulatory system, directly escape out from cyclone separator 2, can't realize fly ash refiring, space malleation beyond distance standpipe 3 top 2000mm is larger, screw(-type) feeder 5 is sent flying dust into 30 minutes difficulties of standpipe, at distance standpipe 3 tops 500mm～2000mm place screw(-type) feeder 5 is installed, screw(-type) feeder 5 can be continuous, the reliable delivery flying dust connects oxygen-enriched air generator 8 at 4-1 place, feeding back device bottom air inlet chamber 4;

2) when CFBB moves, the circulating ash particle of experience burning enters cyclone separator 2 with air-flow from burner hearth 1, centrifugation through cyclone separator 2, the circulating ash particle that separates drops to feeding back device 4 through standpipe 3, behind feeding back device 4, return burner hearth 1 with the fuel that adds, so repeatedly, form the CFBB ash circulatory system, the flying dust that cyclone separator 2 does not separate is collected, screw(-type) feeder 5 is sent the flying dust of collecting into standpipe 3 tops, flying dust amount and the cyclone separator 2 of sending into standpipe 3 separate the mass percent of the circulating ash total amount that enters feeding back device 4 less than 10%, according to field experience, flying dust amount and the cyclone separator 2 of sending into standpipe 3 separate the mass percent of the circulating ash total amount that enters feeding back device 4 less than 10%, the grey circulatory system temperature that is improved by coke burning in the flying dust still is lower than ash fusion point, effectively avoided high-temperature coking, flying dust enters feeding back device 4 through standpipe 3, the oxygen-enriched air generation oxygen-enriched combusting reaction that coke in feeding back device 4 interior flying dusts and oxygen-enriched air generator 8 produce, the shared percent by volume of oxygen is 25%～45% in the oxygen-enriched air, described percentage range 25%～45%, the optimized scope of the Effective Raise boiler efficiency that the oxygen-enriched combustion technology field generally believes, in the reaction, by regulating the shared percent by volume control flying dust ignition temperature of oxygen in the oxygen-enriched air, the flying dust ignition temperature obtains by temperature element 4-2, after the reaction, flying dust and flue gas return burner hearth 1, enter the CFBB ash circulatory system, so repeatedly, so that the CFBB unburned carbon in flue dust significantly reduce.

Embodiment 2

As shown in Figure 2, the circulating fluid bed boiler structure of the present embodiment is identical with embodiment 1, and its step of method that the present embodiment a kind of reduces the CFBB unburned carbon in flue dust is as follows:

1) in the CFBB ash circulatory system, flying dust bubbling fluidized bed 7 is set separately, at feeding back device 4 cone valve 7-2 is installed, the feed pipe 7-3 that connects flying dust bubbling fluidized bed 7 at cone valve 7-2 ash hole place, at the downward-sloping installation screw(-type) feeder 5 in feed pipe 7-3 top, connect burner hearth 1 in flying dust bubbling fluidized bed 7 exits, connect oxygen-enriched air generator 8 at 7-1 place, flying dust bubbling fluidized bed bottom air inlet chamber 7;

2) when CFBB moves, the circulating ash particle of experience burning enters cyclone separator 2 with air-flow from burner hearth 1, centrifugation through cyclone separator 2, the circulating ash particle that separates drops to feeding back device 4 through standpipe 3, part circulating ash is directly returned burner hearth 1 with the fuel that adds behind feeding back device 4, all the other circulating ash particles are sent into feed pipe 7-3 through cone valve 7-2, enter flying dust bubbling fluidized bed 7 through feed pipe 7-3, then return burner hearth 1, so repeatedly, form the CFBB ash circulatory system, the flying dust that cyclone separator 2 does not separate is collected, screw(-type) feeder 5 is sent the flying dust of collecting into flying dust bubbling fluidized bed 7 feed pipe 7-3 tops, flying dust enters flying dust bubbling fluidized bed 7 through feed pipe 7-3, the oxygen-enriched air generation oxygen-enriched combusting reaction that coke in flying dust bubbling fluidized bed 7 interior flying dusts and oxygen-enriched air generator 8 produce, in the reaction, by regulating the shared percent by volume control flying dust ignition temperature of oxygen in the oxygen-enriched air, the flying dust ignition temperature obtains by temperature element 7-4, after the reaction, flying dust and flue gas return burner hearth 1, enter the CFBB ash circulatory system, so repeatedly, so that the CFBB unburned carbon in flue dust significantly reduce.

Embodiment 3

As shown in Figure 3, the CFBB of the present embodiment comprises burner hearth 1, cyclone separator 2, standpipe 3 and feeding back device 4 and external bed 6, and its step of method that the present embodiment a kind of reduces the CFBB unburned carbon in flue dust is as follows:

1) at the downward-sloping installation screw(-type) feeder 5 in external bed 6 feed pipe 6-2 tops, connects oxygen-enriched air generator 8 at 6-1 place, external bed bottom air inlet chamber 6;

2) when CFBB moves, the circulating ash particle of experience burning enters cyclone separator 2 with air-flow from burner hearth 1, centrifugation through cyclone separator 2, the circulating ash particle that separates drops to feeding back device 4 through standpipe 3, part circulating ash is directly returned burner hearth 1 with the fuel that adds behind feeding back device 4, all the other circulating ash are sent into feed pipe 6-3 through cone valve 6-2, enter external bed 6 through feed pipe 6-3, then return burner hearth 1, so repeatedly, form the CFBB ash circulatory system, screw(-type) feeder 5 is sent into flying dust on the feed pipe 6-3 top of external bed 6, flying dust enters external bed 6 through feed pipe 6-3, the oxygen-enriched air generation oxygen-enriched combusting reaction that coke in external bed 6 interior flying dusts and oxygen-enriched air generator 8 produce, in the reaction, by regulating the shared percent by volume control flying dust ignition temperature of oxygen in the oxygen-enriched air, after the reaction, flying dust and flue gas return burner hearth 1, enter the CFBB ash circulatory system, so repeatedly, so that the CFBB unburned carbon in flue dust significantly reduce.

Claims

1. method that reduces the CFBB unburned carbon in flue dust, when CFBB comprised burner hearth (1), cyclone separator (2), standpipe (3) and feeding back device (4), it is characterized in that: the method step was as follows:

1) in distance standpipe (3) top 500mm～2000mm place level screw(-type) feeder (5) is installed, is located to connect oxygen-enriched air generator (8) in feeding back device (4) bottom air inlet chamber (4-1);

2) when CFBB moves, screw(-type) feeder (5) is sent the flying dust of collecting into standpipe (3) top, flying dust amount and the cyclone separator (2) of sending into standpipe (3) separate the mass percent of the circulating ash total amount that enters feeding back device (4) less than 10%, flying dust enters feeding back device (4) through standpipe (3), the oxygen-enriched air generation oxygen-enriched combusting reaction that coke in feeding back device (4) in the flying dust and oxygen-enriched air generator (8) produce, after the reaction, flying dust and flue gas return burner hearth (1).