CN105299683A - Coal combustion process for improving carbon dioxide capturing efficiency - Google Patents

Abstract

The invention discloses a coal combustion process for improving carbon dioxide capturing efficiency. The process includes the following steps that firstly, waste heat recovery, purification and condensing compression are performed on high-temperature flue gas generated by combustion of a boiler, and condensate water separated after condensing compression is heated and converted into steam with the temperature ranging from 210 DEG C to 230 DEG C through recovered heat; secondly, a part of the steam and primary air are fed into a hearth of the boiler, pulverized coal burns in a first combustion flame region, and rotational flow is provided for feeding the pulverized coal into a second flame region; a part of steam and secondary air are mixed and fed into the second flame region where the pulverized coal burns, so that the pulverized coal burns with deficient oxygen in the second combustion flame region; and thirdly, the generated flue gas is treated through a compression system so as to be in the liquid state, and CO2 and condensate water in the gas are separated and recovered. By the adoption of the coal combustion process, the content of NOx and the content of SO2 in the flue gas are prevented from being continuously enlarged along with the increase of the circulation frequency, and meanwhile the capturing efficiency of CO2 is improved.

Description

A kind of coal combustion technique improving carbon dioxide capture efficiency

Technical field

The present invention relates to boiler environmental technology field, particularly a kind of coal combustion technique improving carbon dioxide capture efficiency.

Background technology

The pollutant of fuel combustion discharge is the major part of atmosphere pollution, and smoke components is CO mainly₂, a small amount of water vapour, a small amount of O₂, N₂and pollutant NOx and SO₂.Along with the quick growth of energy demand and the sharply increase of fuel use amount, cause greenhouse gases CO₂continue to increase in natural cumulant, control fuel combustion process CO₂discharge, for reply greenhouse effects and global warming there is important effect.Particularly for China, in view of the feature of its energy resource structure based on coal, CO₂emission level sharply increases and has occupy the present situation of No. 1 in the world, develops efficient coal-fired CO₂emission-reduction technology, controls the coal-fired CO of China₂emission level, has great social effect and economic worth.

Fuel combustion techniques is divided into oxygen-enriched combustion technology and combustion with meagre oxygen technology, combustion with meagre oxygen technology can suppress the generation of NOx, and there is certain energy-saving effect, the energy-saving principle of combustion with meagre oxygen is: recycle high-temperature flue gas, high-temperature flue gas can maintain the high-temperature in burner hearth, thus the fuel quantity that needs are fed and air capacity are just reduced.

But, find after deliberation, directly utilize high-temperature flue gas to carry out circulation and still have a large amount of problem to exist: S1, circulation due to a large amount of flue gas, cause NOx and SO in flue gas₂content can the continuous enrichment along with the increase of cycle-index, flue gas recirculation repeatedly simultaneously can increase air leakage phenomena, and makes N in flue gas₂content increases; CO in S2, reduction combustion with meagre oxygen flue gas₂concentration, and then increase the difficulty of subsequent compression purifying, reduce CO₂capture rate, be unfavorable for CO₂further exploitation; S3, a large amount of flue gas recirculations can cause boiler easily the phenomenons such as fouling to occur, and increase the weight of the burden of boiler attendance.

Summary of the invention

The invention provides a kind of coal combustion technique improving carbon dioxide capture efficiency, while the generation of effective control NOx, can CO be improved₂capturing efficiency.

For achieving the above object, technical scheme of the present invention is:

Improve a coal combustion technique for carbon dioxide capture efficiency, comprise the following steps:

S1, the high-temperature flue gas produced boiler combustion carry out waste heat recovery, purification, condensation compression, isolated condensed water after condensation compression, with the water vapour reclaiming the heat that generates and condensed water heating to be converted to 210 ~ 230 DEG C;

S2, wherein a part of steam and First air are sent into the burner hearth of boiler, the volume ratio of steam and First air is 1 ~ 2:60, makes coal dust in the burning of burning first flame district and with eddy flow, coal dust is sent into the second flame district; Wherein a part of steam mixes with Secondary Air, and send into the second flame district of coal dust firing, the volume ratio of steam and Secondary Air is 1 ~ 2:40, makes coal dust form combustion with meagre oxygen in burning second flame district, at suppression NO_xwhile generating, improve the seizure effect of carbon dioxide in flue gas;

The flue gas of S3, generation is isolated after dust through cyclone separator, carries out waste heat recovery, after gas cleaning, by compressibility, gas treatment is become Liquid segregation recovery CO wherein₂and condensed water, remaining gas is discharged from chimney.

Further, described First air oxygen-supplying amount is 75 ~ 79% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 21 ~ 25% of fuel combustion oxygen demand.

Preferred, described First air oxygen-supplying amount is 78% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 22% of fuel combustion oxygen demand.

Further, when steam required in described step S2 is not enough, converts steam to the waste-heat medium water reclaimed and supply.

The present invention has the following advantages:

(1) the heat heating medium water of high-temperature flue gas is utilized, by mixing of steam and First air and Secondary Air, regulate temperature and the boiler heat exchange state of burner hearth Flame, compared with traditional combustion with meagre oxygen mode, do not recycle the use of circulating flue gas, avoid NOx and SO in flue gas₂content can the continuous enrichment along with the increase of cycle-index, improve CO simultaneously₂capture rate;

(2) strict control First air and Secondary Air send oxygen amount, effectively suppress thermal NO x to be formed;

(3) avoid the repeatedly circulation of flue gas, alleviate the burden of boiler, there is the advantage of energy-conserving and environment-protective;

(4) CO in flue gas is conducive to₂recycling, cost-saving, achieve the development of recycling economy.

Accompanying drawing explanation

Fig. 1 is process flow diagram of the present invention.

Detailed description of the invention

Below in conjunction with specific embodiment, the invention will be further described, but protection scope of the present invention and range of application are not limited to following examples:

Embodiment 1

Improve a coal combustion technique for carbon dioxide capture efficiency, shown in composition graphs 1, comprise the following steps:

S1, the high-temperature flue gas produced boiler combustion carry out waste heat recovery, purification, condensation compression, isolated condensed water after condensation compression, with the water vapour reclaiming the heat that generates and condensed water heating to be converted to 210 ~ 230 DEG C;

S2, wherein a part of steam and First air are sent into the burner hearth of boiler, the volume ratio of steam and First air is 1:30, makes coal dust in the burning of burning first flame district and with eddy flow, coal dust is sent into the second flame district; Wherein a part of steam mixes with Secondary Air, and send into the second flame district of coal dust firing, the volume ratio of steam and Secondary Air is 1:20, makes coal dust form combustion with meagre oxygen in burning second flame district, at suppression NO_xwhile generating, improve the seizure effect of carbon dioxide in flue gas;

The flue gas of S3, generation is isolated after dust through cyclone separator, carries out waste heat recovery, after gas cleaning, by compressibility, gas treatment is become Liquid segregation recovery CO wherein₂and condensed water, remaining gas is discharged from chimney.

Wherein, First air oxygen-supplying amount is 79% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 21% of fuel combustion oxygen demand.

Further, when steam required in described step S2 is not enough, converts steam to the waste-heat medium water reclaimed and supply; Wherein, medium water is that water is put into heater, and the heat utilizing high-temperature flue gas to reclaim heats.

CO after above-mentioned steps purified treatment₂concentration be 91 ~ 92%.

Embodiment 2

Improve a coal combustion technique for carbon dioxide capture efficiency, shown in composition graphs 1, comprise the following steps:

S1, the high-temperature flue gas produced boiler combustion carry out waste heat recovery, purification, condensation compression, isolated condensed water after condensation compression, with the water vapour reclaiming the heat that generates and condensed water heating to be converted to 210 ~ 230 DEG C;

S2, wherein a part of steam and First air are sent into the burner hearth of boiler, the volume ratio of steam and First air is 1:60, makes coal dust in the burning of burning first flame district and with eddy flow, coal dust is sent into the second flame district; Wherein a part of steam mixes with Secondary Air, and send into the second flame district of coal dust firing, the volume ratio of steam and Secondary Air is 1:40, makes coal dust form combustion with meagre oxygen in burning second flame district, at suppression NO_xwhile generating, improve the seizure effect of carbon dioxide in flue gas;

The flue gas of S3, generation is isolated after dust through cyclone separator, carries out waste heat recovery, after gas cleaning, by compressibility, gas treatment is become Liquid segregation recovery CO wherein₂and condensed water, remaining gas is discharged from chimney.

Wherein, First air oxygen-supplying amount is 78% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 22% of fuel combustion oxygen demand.

Further, when steam required in described step S2 is not enough, converts steam to the waste-heat medium water reclaimed and supply; Wherein, medium water is that water is put into heater, and the heat utilizing high-temperature flue gas to reclaim heats.

CO after above-mentioned steps purified treatment₂concentration be 92 ~ 92.5%.

Embodiment 3

Improve a coal combustion technique for carbon dioxide capture efficiency, shown in composition graphs 1, comprise the following steps:

S1, the high-temperature flue gas produced boiler combustion carry out waste heat recovery, purification, condensation compression, isolated condensed water after condensation compression, with the water vapour reclaiming the heat that generates and condensed water heating to be converted to 210 ~ 230 DEG C;

S2, wherein a part of steam and First air are sent into the burner hearth of boiler, the volume ratio of steam and First air is 1:40, makes coal dust in the burning of burning first flame district and with eddy flow, coal dust is sent into the second flame district; Wherein a part of steam mixes with Secondary Air, and send into the second flame district of coal dust firing, the volume ratio of steam and Secondary Air is 1.5:40, makes coal dust form combustion with meagre oxygen in burning second flame district, at suppression NO_xwhile generating, improve the seizure effect of carbon dioxide in flue gas;

The flue gas of S3, generation is isolated after dust through cyclone separator, carries out waste heat recovery, after gas cleaning, by separator pressure recovery CO wherein₂and condensed water, remaining gas is discharged from chimney.

Wherein, First air oxygen-supplying amount is 75% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 25% of fuel combustion oxygen demand.

Further, when steam required in described step S2 is not enough, converts steam to the waste-heat medium water reclaimed and supply; Wherein, medium water is that water is put into heater, and the heat utilizing high-temperature flue gas to reclaim heats.

CO after above-mentioned steps purified treatment₂concentration be 90.0 ~ 90.5%.

Above content is in conjunction with concrete preferred embodiment further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention; make some equivalent alternative or obvious modification without departing from the inventive concept of the premise; and performance or purposes identical, all should be considered as belonging to the scope of patent protection that the present invention is determined by submitted to claims.

Claims (4)

1. improve a coal combustion technique for carbon dioxide capture efficiency, it is characterized in that comprising the following steps:

S1, the high-temperature flue gas produced boiler combustion carry out waste heat recovery, purification, condensation compression, isolated condensed water after condensation compression, with the water vapour reclaiming the heat that generates and condensed water heating to be converted to 210 ~ 230 DEG C;

S2, by wherein a part of steam and First air send into the burner hearth of boiler, the volume ratio of steam and First air is 1 ~ 2:60, First air by the air blasted and circulating flue gas by making coal dust burn in burning first flame district and with eddy flow, coal dust being sent into the second flame district; Wherein a part of steam mixes with Secondary Air, and send into the second flame district of coal dust firing, the volume ratio of steam and Secondary Air is 1 ~ 2:40, makes coal dust form combustion with meagre oxygen in burning second flame district, at suppression NO_xwhile generating, improve the seizure effect of carbon dioxide in flue gas;

The flue gas of S3, generation is isolated after dust through cyclone separator, carries out waste heat recovery, after gas cleaning, by compressibility, gas treatment is become Liquid segregation recovery CO wherein₂and condensed water, remaining gas is discharged from chimney.

2. a kind of coal combustion technique improving carbon dioxide capture efficiency according to claim 1, is characterized in that:

Described First air oxygen-supplying amount is 75 ~ 79% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 21 ~ 25% of fuel combustion oxygen demand.

3. a kind of coal combustion technique improving carbon dioxide capture efficiency according to claim 2, is characterized in that:

Described First air oxygen-supplying amount is 78% of fuel combustion oxygen demand; Described Secondary Air oxygen-supplying amount is 22% of fuel combustion oxygen demand.

4. a kind of recirculated water vapor applications according to claim 1 is in the technique of coal combustion boiler, it is characterized in that:

When steam required in described step S2 is not enough, converts steam to the waste-heat medium water reclaimed and supply.