JPS62177093A - Production of moisture-controlled coal for coke oven - Google Patents

Abstract

PURPOSE:To improve productivity of coke and stabilize moisture content of coal, by increasing the charging rate of stock coal to a coke oven and utilizing waste heat of coke oven, thereby increasing the bulk density of the coal. CONSTITUTION:Feeding coal for coke production is dried to increase the rate of charging of the coal to a coke oven 1 and increase the generation of steam by a boiler attached to a coke dry-quenching apparatus 3. The excess steam is directly used as a heat source of the above process for drying the stock coal. The waste heat of coke oven 1 can be effectively utilized and, at the same time, the productivity of coke can be improved and the moisture content of coal can be stabilized by the increase of the bulk density of coal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for drying coal for coke production, and more particularly to a method for producing humidity-controlled coal for coke ovens that utilizes energy most rationally.

[Conventional technology]

Generally, in order to reduce fuel consumption in a coke oven, coal for coke production is pre-dried to reduce the moisture content to a predetermined amount.

As such a method, Japanese Patent Application Laid-Open No. 59-2046 developed a technology in which coke oven combustion exhaust gas is brought into direct contact with coking coal to dry it.
However, there is a problem in that exhaust gas facilities usually have a low temperature of 100 to 150°C, which is low enough to be used as a heat source for drying, and cannot be used as is.

Furthermore, JP-A-58-37082 and JP-A-58-3
There is a method of wrapping a heat transfer tube around the coke oven gas riser pipe etc. as in 7083, or installing a heat transfer tube in the coke oven exhaust gas as in JP-A-60-31592 and recovering heat using heat transfer oil. Proposed.

In the case of these methods as well, l) the number of riser pipes is the same as the number of kilns in the furnace, and it is necessary to install a large number of them.

2) Since it is located above the furnace, it is difficult to work and the environment is bad, and installation and repair work is difficult.

3) In the case of heat transfer oil, it does not have a large heat storage capacity like steam, and the heat transfer response of the device is poor. For example - in the example,
There is a response delay of about 16 minutes. In addition, a large flow rate of heat transfer oil is required, which increases the size of the equipment.

[Problem that the invention seeks to solve]

The present invention is a rational humidity-controlled coal for coke ovens that effectively utilizes coke oven waste heat, improves productivity by increasing bulk density of coal, and stabilizes coal moisture. It provides a manufacturing method that uses steam, which has a much higher heat retention capacity than heat transfer oil, which allows for smaller equipment and easier backup from other steam sources, resulting in stable operation and improved usage efficiency. .

The present invention provides that when drying coal for coke production, the amount of heat required for coke production can be reduced by directly using the waste heat of the coke oven, especially the heat source of the coke oven's auxiliary equipment, and It was completed by focusing on the fact that it can achieve two effects at the same time: improving quality and productivity.

An object of the present invention is to provide such a rational method for producing humidity-controlled coal for coke ovens.

[Means for solving problems]

The technical means of the present invention to achieve the above object are as follows.

(1) Drying coking coal for coke production and increasing the amount charged into the coke oven, increasing the amount of steam generated by the auxiliary boiler of the coke dry fire extinguishing system.

(2) The surplus amount of steam generated is directly used as the drying heat source to dry the coking coal.

As a heat source for achieving the above technical means, the productivity of the coke oven unit output from the coke oven is increased by increasing the bulk density by drying the coking coal, and the throughput of the coke dry extinguishing system is correspondingly increased, and the generated steam is The principle is to increase the amount of steam, connect it directly to a dryer, and use the surplus steam generated. However, the present invention uses a catalyst to heat coke oven exhaust gas to a high temperature and denitrify it, and then recover the dissipated exhaust gas sensible heat as steam. ), by directly connecting it to a dryer, or by using these steams as a composite system that combines the steam system generated by the coke dry fire extinguishing system with another backup steam system to achieve a wide range of heat source operations. It's not a hindrance.

That is, the process for carrying out the present invention is configured to enable a composite method of utilizing steam obtained by recovering waste heat from coke oven auxiliary equipment as described above, thereby improving coke oven related equipment. In addition to making effective use of waste heat from incidental equipment, it is also possible to incorporate new heat sources in the future, making it possible to configure a process with a wide range of applications.

[Effect]

Coking coal for coke production has a bulk density of approximately 7.5 after drying.
ton/g, which is an increase in bulk density of approximately 8% compared to 6.9 ton/m'' for wet coal. Therefore, the amount of coal charged per coke oven should be increased by 8%. Therefore, for the same operating rate of the coke oven, it is possible to expect production to increase by the same rate.

The existing coke dry fire extinguishing system processes the entire amount of coke ovens, thereby processing the maximum amount that can be handled at any given time. Therefore, the increase in the amount of coking coal charged can be handled as an increase in the throughput without changing the conventional coke dry extinguishing system, and the increased amount of steam generated can be transferred to the coal dryer. By using it as a drying heat source, it is possible to rationally improve production and thermal economy.

In addition, in conjunction with the method of the present invention, the sensible heat of the high-temperature exhaust gas after the combustion exhaust gas from the coke oven is guided to a denitrification device to remove NOx is further recovered as steam, and this is used in the same way to dry coking coal for coke production. By introducing it into the machine, conventionally,
Sensible heat of the exhaust gas after denitrification, which was not effectively used and was released into the atmosphere, can be effectively used. Additionally, other steam such as coke oven riser, coke oven exhaust gas, or other process steam can be used as a backup.
As mentioned above, the present invention does not exclude such methods and systems.

Comparing heat transfer oil and steam as heat sources, steam has the following excellent properties.

b) The flow rate ratio is l/12, which makes the equipment smaller.

) The initial investment will be approximately 1/2.

c) Responsiveness is determined by the flow rate of the heat medium, and in one example where heat transfer oil is used at a location approximately 500 m away from the heat source, there is a delay of 8 minutes due to the increase in the calorific value of coke oven gas due to reheating compared to steam, and the flow rate is 8 minutes. Time delay 8 minutes, total 1
There is a response time delay of about 6 minutes.

〔Example〕

Figure 4 shows a cross-sectional view of the coke oven.

The coke oven 1 is supplied with coking coal from a coal feed tank 61 via a coal charging car 62, and turns it into coke. Carbonization chamber 6
3 and combustion chambers are arranged alternately through the furnace wall, and there is a heat storage chamber 64 below which is heated and maintained by combustion exhaust gas.

The exhaust gas 22 coming out of the heat storage chamber 64 is generally released into the atmosphere through a chimney. Carbonization gas is recovered from the carbonization chamber 63 via a riser pipe 65.

Conventionally, heat has been recovered from the carbonized gas in the riser 65 using a heating medium, and when denitrating the exhaust gas, it is necessary to heat the exhaust gas to a temperature suitable for the reaction of the denitrification catalyst, which reduces heat loss. It was getting louder.

The red-hot coke pushed out of the coke oven is transported by the guide car 6.
6. It is transferred to a coke dry extinguishing system (not shown) via a packet car 67 and cooled. At this time, in the coke dry extinguishing system, steam is recovered by the sensible heat of the coke.

FIG. 1 shows a flow sheet of an apparatus that can suitably carry out the present invention. This flowsheet shows a system that combines a coke dry fire extinguishing system with a steam generator and a heat recovery device after the denitrification device.

To explain this system, a coke dry extinguishing device 3 that is supplied with hot coke 2 from a coke oven 1 cools the coke with circulating air 6 to produce cold coke 4.
A boiler 5 recovers heat from the circulating air 6 to generate steam 8. The generated steam 8 is led to a process line 9 for use in turbine power generation, etc. In addition, according to the present invention, the generated steam 8 is introduced into a coking coal heating line 10.
The raw coal is then supplied to the raw coal dryer 40, where the raw coal is heated and dried. As the dryer 40, for example, an indirect heating rotary dryer is used. The dried coking coal is supplied to a coke oven 1, and the bulk density increases due to drying, resulting in an increase in coke production. This increased production increases the amount of heat recovered from the coke dry extinguishing system, and the amount of generated steam 8 increases. The increased amount of steam generated due to this increased production effect is dried in pipeline 10 *40
Guide to<.

As described below, other steams can also be used and are adjusted to the same pressure in the header 12.

To explain the heat recovery of the denitrification system shown in FIG. 1, the combustion exhaust gas discharged from the coke oven I passes through the flue 21 and is sent to the catalyst-equipped reactor 26 as exhaust gas 22. During this process, air 25 introduced through the heating furnace 24 is mixed, resulting in a gas 27 having an appropriate reaction temperature of 220 to 250°C. This exhaust gas 27 is passed through a boiler 28 and discharged into the atmosphere from a chimney 31. The boiler 28 is equipped with a bypass valve 30 that bypasses exhaust gas in an abnormal state. The generated steam 37 is supplied to the header 12 and, together with the coke dry extinguishing system steam 11, is supplied to the dryer R40.

The steam that has exchanged heat with coking coal in the dryer 40 becomes saturated water, which is collected in a tank 51 and sent by a pump 52 to a boiler water supply tank 33.55 via a pipeline 36.54. Then, the water is re-sent to the boiler 5 together with the boiler feed water 7, and in the denitrification equipment, it is re-sent to the boiler 28 in the form of saturated water by the pump 34. The shortage is replenished with pure water 35.

This system organically combines the characteristics of dry coking coal with a heat recovery system that effectively utilizes waste heat, aiming to produce comprehensive benefits.

Note that it is more preferable to use steam 38 from another heat source as a backup by merging it at the header 12, as this will increase elasticity.

Using the apparatus shown in FIG. 1, the coking coal can be dried, the capacity of the coke oven can be improved, and the surplus generated steam can be used to dry the coking coal, so that the entire system can be operated efficiently.

FIG. 2 is a flow sheet of steam around drying @40 in the example.

In this flow, coke dry extinguishing system steam 11, denitrification steam 37, and backup steam 38 are combined, and header 12
After the pressure gauge 19 and the pressure controller 1B adjust the opening of the control valve, the
The steam pressure is controlled between n'. The selection of this control pressure is determined by the inlet moisture meter 45 of the dryer 40 to determine the target moisture content, e.g.
A computer calculates the pressure of the flow rate corresponding to the % and uses feedforward control to implement this. At this time, it is a great advantage that the flow rate can be changed instantaneously by pressure.

In addition, the moisture on the outlet side of the coke coking coal dryer 40 is measured using a moisture meter 4.
Measure in step 6 to find the deviation from the target value, and from this deviation,
Feedback control of coking coal moisture.

The pressure in the header 12 where each steam collects is controlled as follows.

a) Since the coke dry fire extinguishing bag W steam generation pressure is 20 kg/ctn', the pressure gauge 14
The pressure controller 16 is feedback-controlled by
/crn' steam.

b) Denitrification steam generation The steam is 3 kg/cm', but in order to absorb the fluctuation value during evaporation, the pressure controller 15 is controlled by the pressure gauge 14 so that the outlet pressure is constant at 3 kg/cm'. Feedback control.

C) Backup steam As in a) above, the condition is that the steam is 3 kg/cm' or more, and the pressure is regulated by the pressure controller 17.

- 3 kg/ctn' of steam controlled as described above is pressure-controlled by the pressure gauge 19 in accordance with the above-mentioned coking coal moisture measured at the inlet side of the dryer 40, and is sent from the rotary joint 42 to the dryer 40. supply The steam condensed in the dryer 40 is led to a drain tank 51 as saturated water, and is recirculated to a coke dry fire extinguishing system boiler or a gas boiler for use.

FIG. 3 shows an example in which control is performed through the above process.

This example uses steam from a coke dry extinguishing system as the steam source that requires 20 tons/hour of steam for drying coking coal, and the average moisture content of the coking coal at the entrance of the dryer is 8.7. %, and shows an example in which the target moisture value of 5.0% on the dryer outlet side is controlled to ±0.3% with respect to its temporal fluctuation of ±0.6%. Of course, in this case, if the full amount of steam source for the coke dry fire extinguishing system cannot be obtained, it is possible to use the steam source of the coke oven accessory equipment by appropriately balancing the amount, for example, as follows.

Coke dry fire extinguishing system recovery steam: 6 tons/hour Denitrification boiler recovery steam: 9 tons/hour Backup steam: 5 tons/hour Total:
In the 20 ton/hour example, the throughput of the coke dry fire extinguishing system increases by 8%, and the amount of steam generated also increases by 8%, which can be effectively used as a heat source for drying coking coal. It is now possible to make effective use of exhaust gas after denitrification treatment, which had previously been carried out, and to make effective use of other waste heat recovery steam around the coke oven, resulting in lower equipment costs and energy savings.

〔Effect of the invention〕

According to the coke oven moisture control coal production method of the present invention, coke production increases due to an increase in the bulk density of coking coal due to a decrease in moisture content of the coke oven coking coal, an increase in the throughput of coke dry extinguishing equipment, and steam The overall effect of effective use as a heat source for drying coking coal is achieved by increasing the amount generated.

In addition, compared to conventional methods that use heat transfer oil, it has a large heat exchange capacity, excellent controllability, and excellent responsiveness. It also requires less initial investment and is inexpensive, requires less installation space, and allows for highly efficient operation. It has many advantages such as less damage and easy maintenance and operation.

[Brief explanation of drawings]

Fig. 1 is a flow sheet of an embodiment of the apparatus that can suitably carry out the present invention, Fig. 2 is a control system diagram of the coking coal drying system of the embodiment, and Fig. 3 is a chart showing an example of coking coal moisture control. , FIG. 4 is a sectional view of the main parts of the coke oven. l... Coke oven 2... Hot coke 3...
Coke dry fire extinguishing system 4... Cold coke 5... Boiler 6... Circulating air 7... Boiler feed water 8... Generated steam
9...Process line lO...Coking coal heating pipeline 11...Coke dry fire extinguishing system steam 12...Header 13...Saturated steam 14.19
...Pressure gauge 15.16, 17.18...Pressure controller 37...Denitration steam 38...Backup steam 40...Dryer

Claims (1)

[Claims] 1 Dry coking coal for coke production to increase the amount charged into the coke oven, increase the amount of steam generated by the attached boiler of the coke dry fire extinguishing system, and directly use the generated surplus amount of steam as the drying heat source. A method for producing moisture-controlled coal for a coke oven, comprising drying the coking coal.