JPS60203693A - Disposition of coke dust in dry coke extinguisher - Google Patents

Abstract

PURPOSE:The coke dust which has been collected in the dust collector is combusted in a fluid bed type burner whereby the disposition after coke dust collection is simplified and the recovery of heat in the extinguisher is increased. CONSTITUTION:Coarse coke dust collected in the first dust collector 2 following the cooling oven 1 is fed to the fluid bed type burner 6 where the dust is burned and the circulation gas is utilized on this combustion to control the combustion temperature to the optimum (about 900 deg.C). Then, the coke dust and ash are collected with the sub-collector 12 at the outlet of the burner 6 and fed again to the burner 6 where the coke dust is burned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for treating coke powder in a coke dry extinguishing system that recovers the sensible heat of coke.

[Prior art]

Sensible heat recovery from red-hot coke is described in the Japanese Patent Publication No. 58-'2993.
As described in the publication, red-hot coke is charged from above into a vertical furnace, and circulating gas (at around 150°C) (
The coke is extinguished and cooled by blowing in N2 rich gas) and causing the coke and the gas to flow in opposite directions, and the sensible heat of the coke is reduced to 90%.
The heat recovery system recovers it as hot gas at around 0°C and generates steam in a boiler installed in the latter stage. During this process, the high-temperature circulating gas exhausted from the vertical furnace contains a large amount of coke powder, so a primary dust collector is installed at the outlet of the vertical furnace to prevent wear and tear on the subsequent boiler, circulating gas blower, etc.

A secondary dust collector is installed in front of the circulating gas blower to collect and remove coke powder. In addition, the high-temperature coke powder (around 800°C) collected by the secondary dust collector is cooled by a water-cooled shaker/throat type cooler installed below the dust collector, and then sent to a hopper outside the system via a screw conveyor, groove conveyor, etc. lul! has been processed.

Even finer coke powder is collected by a secondary dust collector, mixed with the coke powder collected by the secondary dust collector, and transported to Honova.

However, the extinguishing and cooling treatment of red-hot coke powder generally has many technical problems, and if cooling is insufficient, combustion will occur during the transportation process.
- If the thickness of the coke inside the water-cooled jacket was made thinner to increase cooling efficiency, hanging would occur within the jacket, causing problems in coke powder discharge. Furthermore, since coke powder transportation and storage equipment must be installed separately, there is also the drawback that a large amount of equipment cost is required.

On the other hand, although this coke powder is mainly used as a raw material for sintered ore, large amounts of coke powder are also generated in other coke manufacturing processes, so the coke powder itself is in surplus in the current production system. For this reason, recovering coke powder collected by dry fire extinguishing equipment is not necessarily beneficial due to the equipment problems mentioned above, and one issue is to make it possible to process it so that it is not discharged outside the system. there were.

[Purpose of the invention]

The object of the present invention is to provide a coke dry extinguishing system that recovers the sensible heat of red-hot coke discharged from a coke oven during the coke manufacturing process, by burning coke powder collected by a dust collector in a fluidized bed combustion system. The aim is to simplify the processing process for coke powder after dust and improve the amount of waste heat recovered from dry fire extinguishing equipment.

[Structure of the invention]

The present invention burns combustibles collected by a dust collector on the downstream side of a cooling furnace in a fluidized bed combustion furnace, mixes the generated hot gas into a high-temperature circulating gas flow path before entering a heat exchanger, and A part of the cold circulating gas after exiting the exchanger is blown into the fluidized bed combustion furnace to control the temperature of the fluidized bed.

[Action of the invention]

In the present invention, in addition to recovering the sensible heat of the red-hot coke in the cooling furnace, the collected coke powder can be combusted and the combustion heat can be recovered by the heat exchanger, and the recovered heat can be improved. Furthermore, the combustion temperature within the fluidized bed can be controlled by the cooling circulating gas discharged from the heat exchanger so that the fluidized bed combustion is carried out optimally.

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

Fig. 1 is a system diagram showing the coke dry extinguishing equipment according to the present invention. A hopper for storing powder, (6) a fluidized bed combustion furnace for burning coke powder in a fluidized bed, (12) an auxiliary dust collector, and (16)
is a foiler that forms a heat exchanger that recovers sensible heat from coke.

The main feature of the present invention is to increase the amount of sensible heat recovery by burning coke powder and to incinerate the coke powder.
).

Below, we will discuss various points regarding fluidized bed combustion of coke powder.

In the coke sensible heat recovery of the coke dry extinguishing equipment described in the conventional example, the coke 15) collected by the secondary and secondary dust collectors is 0.05 mm to lQm as shown in Figure 2.
Most of the particles are in the particle size range of m.

The other side of the combustion method for Coke 45] is 0. (It is difficult to burn if the particles are not smaller than 17 mm,
Since it is necessary to refine the collected coke powder and also to use a combustion aid such as heavy oil, it is not economical and lacks practicality. On the other hand, the particle size is too small for the grate method combustion, and problems such as clogging of the grate and local vents in the grate floor result in 20k
This method is also not economical, as it requires several times the area of the hearth compared to ordinary coal firing, which can only handle a hearth load of about g/m2h.

For the above reasons, in order to obtain optimal combustion of coke, fluidized bed combustion was investigated as an effective combustion method for coke powder.

FIG. 3 is a diagram showing the measurement results of the flow characteristics of coke powder in terms of the relationship between superficial velocity and coke bed pressure drop, and the stable flow region is at superficial velocity Vr = 0.3 m/s or more, i, 5
If m/5fi- is exceeded, the dissipation of coke powder increases.

Figure 4 shows an example of a sensible heat envelope of coke in a fluidized bed, where combustion occurs while producing combustion gas containing a large amount of CO gas, which is approximately 0.8 in terms of air ratio, and is proportional to the amount of supplied air. It was confirmed that the amount of combustion (hearth load) increased. It was found that the combustibility of coke powder in a fluidized bed is very good, and that the fluidized bed combustion method is an appropriate method.

In the case of the fluidized bed combustion method, the fluidized bed combustion temperature of coke powder is about 2000° C., so heat removal is required to lower the fluidized bed temperature.

A fluidized bed boiler system is generally adopted as a method for removing heat within the fluidized bed. However, in coke dry fire extinguishing equipment, it is difficult to use this method because the linked operation between the main circulation system boiler and this fluidized bed boiler becomes complicated. For this reason, we focused on the fact that the circulating gas in coke dry extinguishing equipment is inert, and by blowing part of the circulating gas into the fluidized bed and controlling the cooling of the fluidized bed, it is possible to control the temperature of the fluidized bed. The circulating gas components are N2 as shown in Table 1.
The majority is occupied by CO2, Co, and H2 gases. Therefore, even if coke powder is fluidized with this circulating gas, it will not burn, but rather a reduction reaction of C + CO2 will occur and an endothermic reaction will occur, so it will act as an effective cooling medium to control the temperature of the fluidized bed. It was found that cooling by circulating gas is sufficiently possible.

Table 1 Circulating scum components of coke dry extinguishing equipment In this fluidized bed combustion, a part of this circulating gas and an amount of combustion air are mixed and ejected into the fluidized bed, or they are ejected separately to perform fluidized combustion of coke. The temperature of the fluidized bed is 130
When the temperature rises above 0℃, part of the coke ash becomes molten,
A tuff phenomenon occurs. This deteriorates the fluidization state and reduces coke combustion efficiency, and in extreme cases may lead to blockage of the fluidized bed.

On the other hand, tests have shown that fluidized combustion of coke a can continue stable combustion at temperatures of 550°C or higher.

Therefore, some of the circulating gas is blown into the fluidized bed to raise the fluidized bed temperature to 5.
By controlling the temperature between 50°C and 1300°C, stable fluidized bed combustion can be obtained. Furthermore, since the gas produced by this fluidized bed combustion contains about 10% CO, it is possible to increase the amount of recovered heat by, for example, supplying secondary air to carry out two-stage combustion. In addition, in order to prevent coke solution loss in a vertical cooling furnace, it is possible to mix the coke solution into the circulating gas while maintaining a high CO content.

Here, in the fluidized bed combustion process, the minute coke No. 5) is likely to fly apart, but if you try to suppress this scattering, the hearth load will be small, the hearth area will be large, and the equipment cost will increase. In the present invention, FIG. 5 shows the relationship between the hearth load and the superficial velocity of the fluidized bed when the fluidized bed temperature is controlled at 900°C. It was found that as the hearth load approached 500 Xl03kcal/m'h, the flying fit of coke powder became large and the combustion efficiency of coke powder decreased. As a countermeasure for this,
A dust collector was installed at the outlet of the fluidized bed to collect the coke powder that had been scattered along with the hot gas, and to return the coke powder to the fluidized bed. This circulating combustion method of coke powder allows sufficient combustion of coke powder regardless of the residence time of the coke powder in the fluidized bed or the particle size of the coke, making it possible to achieve high coke powder combustion efficiency.

As described above, the coke powder after the second dust collection is supplied to the fluidized bed combustion furnace for fluidized bed combustion, and during this combustion, the circulating gas is used to control the optimum combustion temperature, and the dust is collected at the exit of the combustion furnace. The structure of the present invention is to incinerate the coke by feeding it again into the same combustion furnace, and FIG. 1 described above shows one embodiment of the system.

Hereinafter, the method for treating coke powder will be described in detail with reference to FIG.

First, red-hot coke is charged from above into the vertical cooling furnace (1), circulating gas at around 150°C is blown from below, coke and circulating gas are made to flow counter-currently, the coke is extinguished and cooled, and the circulating gas is heated to hot gas around 900°C. This hot gas contains a large amount of coke dust, and the coarse coke dust is collected in a secondary dust collector (2). This coke powder is temporarily placed in the hopper (3) while still in a red hot state. Then, while measuring the level with the level meter (4), turn off the coke powder cutoff valve (
In step 5), it is charged into the fluidized N combustion furnace (6). Combustion air is blown by the blower (7), but the amount of air is controlled by the cut-off valve (
It is controlled by the regulating valve (8) according to the rotation speed signal of 5). Place a thermometer (00) in the fluidized N combustion furnace (6),
In order to control the fluidized bed temperature to 900°C in this example, a part of the circulating gas was pressurized by a pressure booster (9N), and the flow rate was controlled by a flow control valve (11) to cool the temperature inside the fluidized bed. ing.

In this way, the temperature of the fluidized bed is controlled at 900°C to fluidize the coke powder, but the fine coke powder is scattered and mixed with the combustion gas in the fluidized I'Fli combustion furnace (6).
Go outside. This coke powder and ash are collected by the Teisuke dust collector (12), and the level is set to 4 (11) using the level needle (13), and then transferred to the fluidized bed fA furnace (6) using the cutoff valve (I4). The coke ash is circulated and fluidized again for combustion.The coke ash is discharged from the overflow port (15).

The hot gas containing CO after dust removal is transferred to the secondary combustion chamber (21
) is further combusted by the secondary air whose flow rate is regulated by the regulating valve (22), mixed with the main circulating gas, and sent to the boiler (16).
), fine dust is collected by a secondary dust collector (17), and air is blown by a circulation blower (18). Since the amount of this circulating gas increases due to the combustion of coke powder, the pressure of the circulating gas main pipe (19) is measured and the pressure is controlled by discharging the gas to the atmosphere using the pressure regulating valve (20) to keep this pressure constant. do.

Incidentally, in this method, it is of course possible to supply the coke powder collected by the secondary dust collector Ia (17) or the coke powder generated elsewhere to the hopper (3) and burn it.

In addition, the amount of red-hot coke charged fluctuates widely in the boiler (16
), a method of suppressing the load fluctuation of the boiler (16) can be taken by controlling the amount of coke powder burned.

〔Effect of the invention〕

As described above, the coke dry extinguishing equipment according to the present invention has the following effects.

l) Fluidized bed combustion of coke powder collected by a dust collector eliminates the need for extinguishing and cooling red-hot coke powder or transporting it to a distant hopper, and the amount of heat recovered from coke powder combustion increases, reducing equipment investment. Increased efficiency.

ii) The temperature of the fluidized bed can be controlled with high accuracy by cooling the fluidized bed using a part of the circulating gas, and this generated gas is mixed with the circulating gas from which the sensible heat of the coke has been collected and By recovering heat in the same boiler, it has better controllability and lower equipment costs than a fluidized bed boiler system.

iii) Boiler efficiency is improved by controlling the amount of coke powder processed so as to keep the boiler load constant in accordance with fluctuations in the amount of red hot coke in the cooling furnace.

iv) By controlling the composition of combustion gas according to the CO concentration of circulating gas, solution loss of coke lumps in the cooling furnace can be reduced.

[Brief explanation of the drawing]

Figure 1 is a system diagram for carrying out the coke powder processing method according to the present invention, and Figure 2 shows the particle size distribution of coke powder collected by primary and secondary dust collection in conventional coke powder processing equipment. Graph, Figure 3 is a graph showing the flow characteristics of coke powder, Figure 4 is coke in a fluidized bed 15)
Figure 5 is a graph showing the combustion characteristics of
This is a graph showing the relationship between the hearth load and the superficial velocity of the fluidized bed at the time of "C". Blower (9) Booster (12) Dust collector (16) Boiler (heat exchanger) (21) Secondary combustion chamber Patent applicant Nippon Steel Corporation agent Masu Tegori (and one other person) Part l Figure 2 Figure grain diameter (mm)

Claims (1)

[Claims] 1. In a dry fire extinguishing system in which high-temperature coke is cooled by circulating gas, combustibles are removed from the high-temperature circulating gas after cooling the coke by a dust collector, and sensible heat is recovered by a heat exchanger. The collected combustibles are burned in a fluidized bed combustion furnace, and the generated hot gas is mixed into the high-temperature circulating gas flow path before entering the heat exchanger, and one of the cold circulating gases after exiting the heat exchanger. A method for treating coke powder suitable for coke dry extinguishing equipment, characterized by controlling the temperature of the fluidized bed by blowing a part of the coke powder into the fluidized bed combustion furnace.