Process and system for waste heat grading cyclic utilization and pollutant emission reduction of sintering flue gas

Abstract

The present invention provides a process and system for waste heat grading cyclic utilization and pollutant emission reduction of sintering flue gas, in which the sintering flue gas is divided into low-temperature, high-oxygen, low-humidity section sintering flue gas; middle-temperature, low-oxygen, high-humidity section sintering flue gas; and high-temperature, high-oxygen, low-humidity section sintering flue gas according to the emission characteristics of temperature, oxygen content and humidity of the flue gas. The low-temperature, high-oxygen, low-humidity section sintering flue gas is led into the sintering machine for hot air ignition and hot air sintering; the middle-temperature, low-oxygen, high-humidity section sintering flue gas is subjected to dust removal and desulfurization treatments; the high-temperature, high-oxygen, low-humidity section sintering flue gas is mixed with exhaust gas of a cooler and then is led into the sintering machine for hot air sintering. The present invention can conduct grading utilization to the flue gas and recycle low-temperature sensible heat in flue gas, making the carbon monoxide left in the sintering flue gas burn again and thus saving energy consumption in the sintering process, on the premise that the quality and yield of the sintered ores are ensured. The present invention can also conduct cyclic utilization to the flue gas and thereby reduce pollutant emissions and the total emissions of sintering flue gas per unit of the sintered ores. Thus, the present invention has a very high value on energy saving and emission reduction.

Claims

1. A process for waste heat grading cyclic utilization and pollutant emission reduction of sintering flue gas comprising: dividing the sintering flue gas into low-temperature, high-oxygen, low-humidity section sintering flue gas, middle-temperature, low-oxygen, high-humidity section sintering flue gas and high-temperature, high-oxygen, low-humidity section sintering flue gas; conducting the low-temperature, high-oxygen, low-humidity section sintering flue gas into a sintering machine for hot air ignition and hot air sintering; discharging the middle-temperature, low-oxygen, high-humidity section sintering flue gas after desulfurization treatment; and mixing the high-temperature, high-oxygen, low-humidity section sintering flue gas with waste gas of a cooler and then conducting said mixture into the sintering machine for hot air sintering.

2. The process of claim 1, further comprising adjusting the ratio of sintering raw materials, fabric thickness, throttle opening of the air exhauster and operating speed of the sintering machine, and adjusting the temperature, oxygen and humidity distributions of the sintering flue gas in the sintering machine by calculating each heat income and expenditure during the sintering process and establishing CFD dynamic heat transfer model, thereby dividing the sintering flue gas into low-temperature, high-oxygen, low-humidity section sintering flue gas, middle-temperature, low-oxygen, high-humidity section sintering flue gas and high-temperature, high-oxygen, low-humidity section sintering flue gas.

3. The process of claim 1, further comprising conducting the low-temperature, high-oxygen, low-humidity section sintering flue gas into the sintering machine after dust removal treatment for hot air ignition and hot air sintering.

4. The process of claim 1, further comprising discharging the middle-temperature, low-oxygen, high-humidity section sintering flue gas after dust removal and desulfurization treatment and SO.sub.2 content thereof.

5. The process of claim 1, further comprising mixing the high-temperature, high-oxygen, low-humidity section sintering flue gas with exhaust gas of the cooler after dust removal treatment.

6. The process of claim 1, wherein the temperature of the low-temperature, high-oxygen, low-humidity section sintering flue gas is 50-100 C.; the temperature of the middle-temperature, low-oxygen, high-humidity section sintering flue gas is 100-250 C.; and the temperature of the high-temperature, high-oxygen, low-humidity section sintering flue gas is 250-350 C.

7. The process of claim 1, wherein the oxygen content of the low-temperature, high-oxygen, low-humidity section sintering flue gas is 18-21%; the oxygen content of the middle-temperature, low-oxygen, high-humidity section sintering flue gas is 11-15%; and the oxygen content of the high-temperature, high-oxygen, low-humidity section sintering flue gas is 18-21%.

8. The process of claim 1, wherein the humidity of the low-temperature, high-oxygen, low-humidity section sintering flue gas is 0-4%; the humidity of the middle-temperature, low-oxygen, high-humidity section sintering flue gas is 4-10%; and the humidity of the high-temperature, high-oxygen, low-humidity section sintering flue gas is 0-4%.

9. The process of claim 1, wherein the exhaust gas of the cooler mixed with the high-temperature, high-oxygen, low-humidity section sintering flue gas represents 25-35% by volume of the total amount of the exhaust gas of the cooler.

10. The process of claim 1, wherein the high-temperature, high-oxygen, low-humidity section sintering flue gas introduced into the sintering machine represents 15-25% by volume of the total amount of the sintering flue gas.

11. The process of claim 1, wherein the low-temperature, high-oxygen, low-humidity section sintering flue gas introduced into the sintering machine represents 15-25% by volume of the total amount of the sintering flue gas.

12. A system for processing waste heat grading cyclic utilization and pollutant emission reduction of sintering flue gas of claim 1, comprising a sintering machine, the bellows of which are divided into low-temperature, high-oxygen, low-humidity section bellows, middle-temperature, low-oxygen, high-humidity section bellows and high-temperature, high-oxygen, low-humidity section bellows, wherein the low-temperature, high-oxygen, low-humidity section bellows are connected to an ignition furnace of the sintering machine and a sealing hot air cover of the sintering machine; the middle-temperature, low-oxygen, high-humidity section bellows are connected to a desulfurization device; and the high-temperature, high-oxygen, low-humidity section bellows are connected to the sealing hot air cover of the sintering machine through a mixing chamber which is further connected to a cooler.

13. The system of claim 12, wherein the low-temperature, high-oxygen, low-humidity section bellows are connected to the ignition furnace of the sintering machine and the sealing hot air cover of the sintering machine after being connected to a dust removal device.

14. The system of claim 12, wherein the middle-temperature, low-oxygen, high-humidity section bellows are connected to a desulfurization device and a chimney successively after being connected to a dust removal device.

15. The system of claim 12, wherein the high-temperature, high-oxygen, low-humidity section bellows are connected to a mixing chamber after being connected to a dust removal device.

16. The system of claim 12, wherein the dust removal device is any one of a cyclone deduster, a bag filter or an electric bag filter, or a combination of at least two of them.

17. The system of claim 12, wherein the desulfurization device is any one of a circulating fluidized bed semi-dry desulfurization device, a SDA desulfurization device or a wet desulfurization device, or a combination of at least two of them.

18. The system of claim 12, wherein a hood is respectively set at both the head and tail of the sintering machine, and the sealing mode thereof is a negative pressure labyrinth seal.

Description

DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is a system diagram of Example 1 of the present invention.

[0041] FIG. 2 is a variation diagram of the temperature and humidity of the sintering flue gas along the length of the sintering machine according to the present invention.

[0042] FIG. 3 is a variation diagram of the temperature of the sintering flue gas and the O.sub.2 concentration along the length of the sintering machine according to the present invention.

REFERENCE NUMBERS

[0043] 1sintering machine; 2ignition furnace; 3hood; 4sealing hot air cover; 5draught fan; 6mixing chamber; 7cooler; 8dust removal device; 9desulfurization device; 10chimney; {circle around (1)}{circle around (4)}low-temperature, high-oxygen, low-humidity section bellows; {circle around (5)}{circle around (18)}middle-temperature, low-oxygen, high-humidity section bellows; {circle around (19)}{circle around (22)}high-temperature, high-oxygen, low-humidity section bellows.

DETAILED DESCRIPTION

[0044] The present invention is further described by the following non-limiting embodiments in the detailed description along with the figures.

EXAMPLES

[0045] As shown in FIG. 1, the system comprises a sintering machine 1, {circle around (1)}{circle around (4)} represent low-temperature, high-oxygen, low-humidity section bellows, {circle around (5)}{circle around (18)} represent middle-temperature, low-oxygen, high-humidity section bellows, and {circle around (19)}{circle around (22)} represent high-temperature, high-oxygen, low-humidity section bellows. Wherein, the low-temperature, high-oxygen, low-humidity section bellows {circle around (1)}{circle around (4)} are connected to an ignition furnace 2 of the sintering machine 1 and a sealing hot air cover 4 of the sintering machine 1 respectively after being connected to a dust removal device; the middle-temperature, low-oxygen, high-humidity section bellows {circle around (5)}{circle around (18)} are connected to a desulfurization device 9 and a chimney 10 successively after being connected to a dust removal device; and the high-temperature, high-oxygen, low-humidity section bellows {circle around (19)}{circle around (22)} are connected to the sealing hot air cover 4 of the sintering machine 1 through a mixing chamber 6 which is further connected to a cooler 7 after being connected to a dust removal device 8.

[0046] As shown in FIG. 1, on a sintering machine 1 having an area of 200 m.sup.2, which is equipped with a main exhaust blower having a main exhaust volume of 1 million m.sup.3/hr, the sintering flue gas (250-350 C., 180 thousand m.sup.3/hr) in the high-temperature, high-oxygen, low-humidity section bellows {circle around (19)}{circle around (22)} at the tail of the sintering machine is drawn out through a circulating pipeline, and led back through a dust removal device 8 and a draught fan, introduced into a mixing chamber 6 and mixed with the exhaust gas (180 thousand m.sup.3/hr, 200 C.) which is from a cooler 7 and drawn out by a draught fan, and then circulated to a sealing hot air cover 4 of the sintering machine 1; the sintering flue gas (50-100 C., 180 thousand m.sup.3/hr) in the low-temperature, high-oxygen, low-humidity section bellows {circle around (1)}{circle around (4)} at the head of the sintering machine is drawn out through a circulating pipeline, and led back through a dust removal device and a draught fan, and then circulated to an ignition furnace 2 and a sealing hot air cover 4 of the sintering machine 1 for reuse; the sintering flue gas in the middle-temperature, low-oxygen, high-humidity section bellows {circle around (5)}{circle around (18)} at the middle of the sintering machine is drawn out through a circulating pipeline, and led back through a dust removal device and a draught fan, and subjected to desulfurization through a desulfurization device 9, and then discharged through a chimney 10.

[0047] This example can reduce the total amount of the flue gas discharged by the main exhaust blower of the sintering machine by 20% or more, and reduce the emission of exhaust gas of the cooler by 30%, and save energy 4.5-5 kgce/t-s per ton of the sintered ore.

[0048] The above examples explain the implementation idea of the present invention, and are not the only structural characteristics and means. The present invention is not limited to the above detailed structural characteristics and means; that is to say, it does not mean that the present invention must rely on the above detailed structural characteristics and means to be implemented. Those skilled in the art to which the present invention belongs should appreciate that any improvement to the present invention, equivalent replacement to the selected components of the present invention and added auxiliary components, and choice of specific embodiments will all fall into the scope protected and disclosed by the present invention.

[0049] The above description describes the preferred embodiments of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Simple variants of the technical solutions of the present invention can be made within the scope of the technical conception of the present invention, and these simple variants all fall into the scope of the present invention.

[0050] It also needs to be noted that each specific technical feature described in the above embodiments can be combined in any suitable manner in the case of non-contradiction. In order to avoid unnecessary repetition, the present invention does not make further description for various possible combinations.

[0051] In addition, any combination of the various embodiments of the present invention can also be made and should be deemed as a disclosure of the present invention, as long as it is not contrary to the thought of the invention.