JPS62263934A - Operating method for auxiliary facility to refining furnace - Google Patents

Abstract

PURPOSE:To reduce the amount of expensive liquid fuel to be used, by forming the fuel to be used in a steam heater into a structure of the mono-fuel combustion of solid fuel or the multi-fuel combustion of solid and liquid fuels and by operating so that combustion exhaust gas temp. is a specific temp. CONSTITUTION:The fuel used in a steam heater 5' attached to a refining furnace 3 producing copper by the use of sulfide concentrate as main raw material has a structure capable of mono-fuel combustion of solid fuel or multi-fuel combustion of solid fuel and liquid fuel and, moreover, operation is carried out so that exhaust gas temp. of the steam heater 5' is 500-650 deg.C. In this way, the heating surface area necessary to obtain the same amount of steam is sharply reduced, so that cost of installation of the steam heater 5' can be remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of operating energy utilization equipment attached to a smelting furnace that produces scissors using sulfide concentrates such as copper as a main raw material.

[Conventional technology]

Conventional steel sulfide concentrates can be used, for example, to recover waste heat from flash furnaces,
In order to preheat and dry the concentrate, a combination of auxiliary equipment as shown in Figure 2 is used, and among these equipment, the equipment that requires fuel is a concentrate drying equipment 2, a smelting furnace 3, and a steam heater. 5
and steam reheater 7, respectively.
3 and 14, and conventionally these fuels were generally heavy oil.

Due to the recent rise in the price of heavy oil, some or all of the heavy oil used as the fuel 12 supplied to the shaft of the smelting furnace 3 has been replaced with solid fuels such as pulverized coal, pulverized coke, and oil coke. . However, the fuel 13, 14 used in the steam heater 5 and the steam reheater 7 is conventional heavy oil. Until now, both of these facilities have been built to burn heavy oil, and the problem was that the combustion chamber volume required to use solid fuel was insufficient, and that the water pipes had ample space to accommodate the generation and adhesion of combustion ash. It was not possible to easily switch to solid fuel because it did not have a soot flow facility, and it did not have a mechanism to discharge the unburned content and combustion ash that accumulates on the hearth outside the furnace. .

In addition, the concentrate drying equipment 2 uses the combustion exhaust gases of the fuels 13 and 14 used in the steam heater 5 and the steam reheater 7 as a heat source, but the insufficient amount of heat is made up by burning the fuel 11 in the hot blast furnace 1. This is supplemented by using hot air 21 generated by this process. This fuel 11 brings the combustion gas from the hot air stove 1 installed close to the drying equipment 2 into direct contact with the flammable copper concentrate, so when solid fuel is used, ignited red-hot particles peculiar to the combustion of solid fuel are generated. Heavy oil is a safe and reliable fuel for the fuel 11 since there is a risk of ignition, fire, or other accidents due to direct contact with the concentrate. For safety, the temperature of the two drying facilities was kept below 450C. An indirect heating method using solid fuel combustion gas is also considered, but this is not an economical method in terms of thermal efficiency and equipment costs.

On the other hand, oxygen 27 is used in part or all of the reaction air 22 in order to replace the fuel 12 supplied to the smelting furnace 3 and to increase the ore processing capacity.

When air is enriched with oxygen as a reaction gas in a flash smelting furnace, the amount of fuel supplied to the smelting furnace shaft decreases as the amount of oxygen used increases, so the amount of oxygen used depends on the ore. It is decided by comprehensively taking into consideration the increase in processing capacity, oxygen production cost, fuel cost, etc. In this case, since the amount of exhaust gas 23 from the smelting furnace 3 also decreases, the amount of generated steam 24 from the waste heat boiler 4 decreases, and the amount of fuel 13 in each of the steam heater 5 and the steam reheater 7 decreases in proportion. and 14 decrease, and the amounts of these combustion exhaust gases 25 and 28 also decrease, so the amount of heat supplied to the drying equipment 2 becomes insufficient, and the amount of fuel 11 used in the hot air stove 1 must be increased.

In this way, when oxygen 27 is used in the smelting furnace reaction air 22, the amount of gas to be heated by the air preheater 6 is reduced, and in this case, the amount of heat required for the air preheater 6 is reduced. This is greater than the rate of decrease in the amount of steam 24 generated in the waste heat boiler 4, so if the temperature of the reaction air 22 heated by the air preheater 6 is kept the same as before, the steam temperature at the beginning of the air preheater 6 will be lower than before. A situation occurs in which the amount of fuel 14 used for reheating in the steam reheater 7 must be reduced to such an extent that stable combustion in the burner becomes difficult. In order to prevent this, the amount of fuel 13 used in the steam heater 5 is reduced to lower the outlet steam temperature of the steam heater 5, thereby maintaining the outlet steam temperature of the air preheater 6 at an appropriate level and reheating the steam. When the burner of the reactor 7 is enabled to perform stable combustion, the amount of heat supplied to the reaction air 22 is reduced, so its temperature is lowered, and the effect of reducing the amount of fuel 12 supplied to the smelting furnace 3 is reduced. There was a drawback.

[Problem that the invention seeks to solve]

This invention replaces the expensive fuel of the heavy oil-fired steam heater in the prior art with cheap pulverized solid fuel such as pulverized coal, pulverized coke, or oil coke, and reduces the consumption of the entire smelting furnace ancillary equipment. Operation of ancillary equipment that can reduce overall energy costs by indirectly replacing part of the heavy oil with cheap solid fuel and eliminating the drawbacks that occur when oxygen is enriched in the reaction air. 0 [Means for solving the problem] To achieve this purpose, the conventional equipment G shown in FIG.
Here, by making it possible to use solid fuel as the fuel used in the steam heater 5, and operating the combustion exhaust gas temperature of the silica steam heater 5 to 500 to 650C, which is higher than before, A part of the heavy oil used in the hot air furnace that supplies hot air to the concentrate drying equipment G is strained so that it can be directly replaced with solid fuel.The present invention will be explained with reference to FIG. In the present invention (see FIG. 2), instead of the conventional steam heater 5 shown in FIG.
The ability to create a structure that allows the combustion of only solid fuels such as pulverized coal, coke powder, and oil coke), the co-firing of heavy oil and solid fuel, and the exclusive combustion of heavy oil.

Generally, heat equipment such as a steam heater 5' is used.
In order to increase the thermal efficiency of unit equipment, the exhaust gas temperature is operated to be as low as possible within a range that does not cause problems such as dew point. However, in the present invention, the temperature of the exhaust gas from the steam heater 5' is increased to increase the amount of inexpensive solid fuel consumed thereby, thereby increasing the amount of inexpensive solid fuel used in the hot blast furnace 1 that is used in the hot blast furnace 1 to produce hot air to be supplied to the drying equipment. We considered reducing the amount of liquid fuel. As a result, the concentrate treated in drying equipment 2 is a combustible sulfide, and its ignition temperature was measured to be approximately 350υ
Once ignited, there is a risk of generation of SO gas, dust explosion, sintering of the concentrate, and equipment fire. Therefore, the flow of the concentrate and the heated gas is carried out in parallel, and the temperature of the hot gas supplied is conventionally 45.
Approximately 0C was thought to be the upper limit, but an investigation using actual equipment revealed that there is no risk of ignition or generation of SO gas up to a hot gas temperature of approximately 650C, so the steam heater 5' The present invention is configured to operate at an exhaust gas temperature of 500C or more and 6500C or less.

In the present invention, the exhaust gas temperature of the steam heater 5' is set to 450C.
When increasing from (Case A: conventional operating temperature) to 600 U (Case B: operating temperature of the present invention), the heat transfer area required to obtain the same amount of steam increases as shown in Table 1 for comparison. This is advantageous because the cost of equipment for a steam heater that can use pulverized coal is greatly reduced.

Table 1 In this way, the steam heater 5' is enabled to use solid fuel, only pulverized coal is used, and the exhaust gas temperature is increased to 600C.
(Case B'), when only heavy oil is used as fuel and the exhaust gas temperature is 6000C (Case O), and when only heavy oil is used as fuel and the exhaust gas temperature is 450C (Case D). Table 2 shows a comparison of the fuel consumption of hot blast furnaces required for steam heaters and drying equipment, assuming that the amount of raw materials charged into the smelting furnace, the oxygen concentration of the blast air, and other operating conditions are the same. .

Table 2: Heavy oil calorific value 9800 Cai/9, pulverized coal calorific value 6500 cal/kg, dry concentrate amount 70 T/H, smelting furnace charged concentrate amount 62.6 T/H, wrinkle Ou grade 56 weight %, the oxygen concentration in the reaction air was 26.4% by volume, the amount of pulverized coal supplied to the smelting furnace shaft was 2680 kg/H, and the amount of steam introduced into the steam heater was 40 T/H.

As is clear from Table 2, according to the present invention, the entire amount of heavy oil in the steam heater and a part of the heavy oil used in the drying equipment can be replaced with solid fuel.

In addition to the operating method of the invention described above, this invention further provides a countermeasure against the difficulty of stable combustion in a steam reheater, which occurs when oxygen is enriched in the reaction air in a smelting furnace. Opportunity to reduce the supply of cheap solid fuel (i.e., in this smelting furnace ancillary equipment, if the steam generated by the exhaust heat recovery boiler of the converter that processes the matte produced in the smelting furnace is not introduced into the steam reheater) In order to achieve the purpose of eliminating the above-mentioned problems and making the use of solid fuel as a cheap energy source more efficient, the present invention further adds to the above-mentioned invention a cooling water injector at the steam outlet of the air preheater. When the steam generated by the exhaust heat recovery boiler is not introduced, can you inject water into the cooling water injector to increase the steam temperature at the steam reheater inlet? It is configured to operate at a lower temperature.

With this configuration, part of the heavy oil used in the steam reheater can be converted into solid fuel in the steam heater 5'. In some cases, a steam reheater may not be necessary.

The superheated steam produced from the steam heater that uses solid fuel is used to preheat the reaction gas in the smelting furnace, and the remaining steam that has passed through the air preheater is used to readjust the temperature in the steam reheater and is used to generate electricity. When considering how to maximize the economic effect of a steam heater in a private power generation system generally used in a smelter, it is natural to maximize the steam temperature at the steam heater 5' outlet and reduce the amount of fuel used. maximum, and use the combustion exhaust gas to reduce the amount of heavy oil used in the hot stove 1.
It is considered most efficient to keep the steam heat input of the steam reheater high, reduce the amount of heavy oil used in the steam reheater, or eliminate the steam reheater.

However, as the reaction gas in the smelting furnace is enriched with oxygen and its concentration is increased, the amount of supplementary heat required by the steam reheater becomes below the lower limit of stable combustion of the burner, as described in the prior art section. If you try to achieve stable combustion, the steam temperature in the steam reheater will rise and exceed the heat resistant temperature of the steam reheater, which is inconvenient.

Therefore, in order to perform the most efficient operation, a cooling water injector 9 is installed at the steam outlet of the air preheater 6 in FIG. The steam reheater inlet steam temperature was reduced to allow the burner to burn stably. Normally, in order for a heavy oil burner to perform stable combustion, it is necessary to operate it at a burner capacity of about 115 or more.

A detailed explanation will be given below using an example of operation of a smelting furnace.

The operating conditions for the smelting furnace are: total charge amount of concentrate, solvent, repeated dust, etc. 62.6t/H1 production 56% by weight;
Amount of oxygen used with a purity of 90% by volume: 3060 Nm/H, Amount of air blown to the shaft: 35.950 Nm/H, Amount of pulverized coal supplied to the shaft: 248 kti7H, Amount of waste heat boiler gas: 53,300 Nm/H (Boiler generated steam FIG. 3 shows changes in the amount of pulverized coal supplied to the shaft section when the amount of oxygen used is varied based on the amount of pulverized coal (49 t/h). From this figure, the amount of oxygen used with a purity of 90% by volume is 100%.
If the amount of pulverized coal increases by 0 Nm/H, the amount of pulverized coal will be approximately 370 kti.
It can be seen that /H decreases. In addition, the relationship between the amount of oxygen used, the amount of air supplied to the shaft section, and the amount of waste heat boiler log gas is
As shown in the figure. From this figure, the amount of oxygen used is 1000 Nm.
/H increases, the amount of air supplied to the shaft is approximately 5900
Nm/H, waste heat boiler man-log gas amount is approximately 6200 N
This has the effect of reducing each m/H. FIG. 5 shows the relationship between the amount of oxygen used, the amount of steam generated by the waste heat boiler, and the amount of recovered electricity.

The amount of oxygen used in the smelting furnace depends on the amount of ore processed,
It should be determined by comprehensively taking into account the reduction in the amount of solid fuel, the reduction in operating power due to the reduction in the amount of gas, and the production cost of oxygen, but as shown in Figure 5, the amount of oxygen used is 1100.
When the ON/H increases, the amount of recovered electricity decreases by about 1200 KWH due to the decrease in the amount of waste heat boiler gas, which becomes a major factor in the amount of oxygen used.

When increasing the throughput in a smelting furnace of a certain size, it is necessary to prevent the amount of heat generated within the reaction zone from increasing in proportion to the throughput in order to protect the furnace materials that make up the reaction zone. Generally, the amount of oxygen enrichment is increased as much as possible. This also has the effect of suppressing dust generation.

The charging amount of the smelting furnace and the weight percent of produced acid Cu are the same as above, but the amount of oxygen used is increased to 4750 Nm/H). - Figure 6 shows the relationship between the steam temperature at the outlet of the steam heater, the air temperature and steam temperature at the outlet of the air preheater, and the amount of heavy oil used in the steam reheater when there is no water heater. In Figure 6, if the steam temperature at the steam heater outlet is 460C, the steam and blast temperatures at the air preheater outlet are 375C and 405C, respectively, and when converter waste heat recovery steam is not introduced, the heavy oil in the steam reheater is heated to the burner. Those operating at 9/H at about 50, which is the lower limit of
The amount of heavy oil at the time of introduction of converter boiler steam is 210 to 97H. When the steam temperature at the outlet of the steam heater is increased to 540 C, the steam and blast temperatures at the outlet of the air preheater become 435 tZ' and 470 ic, respectively, but at this time, the heat input to the steam reheater increases. , when the converter boiler steam is introduced, the amount of heavy oil is approximately 50/9/H, which is the lower limit of the burner, and when no converter boiler steam is introduced, the amount of heavy oil is approximately 1/H in terms of calorific value.
00kq/H heavy oil becomes excessive, and the burner is set to the lower limit of 50kq/H.
If combustion continues at 9/H, the steam temperature at the outlet of the steam reheater, which is constantly controlled at 390C, will rise to 450C, exceeding the heat-resistant temperature of this steam reheater of 400C. Since the steam heater could not be operated at high temperatures, it was necessary to lower the steam temperature at the outlet of the steam heater as described above.

In the present invention, since a cooling water injector is provided at the outlet of the air preheater, the cooling water injector is used to inject water without lowering the steam temperature at the steam heater outlet, and when converter boiler steam is not being introduced, the cooling water injector is used to inject water. Lower the steam temperature at the outlet to about 380C,
In the steam reheater, combustion is maintained at 50/9/H, which is the lower limit of the heavy oil burner capacity, and the steam temperature at the steam reheater outlet is maintained at 390C, which is below its heat-resistant temperature.

According to the method of the present invention, since water is injected by the cooling water injector, the amount of steam increases and the amount of steam introduced into the steam turbine 8 increases, and the amount of power generation increases. It is based on solid fuel. Also, when there is no inflow of converter boiler steam, the steam from the air preheater is heated to a temperature suitable for steam turbine operation using a cooling water injector, and when converter boiler steam is inflow, the steam from the air preheater is heated to a temperature suitable for operating the steam turbine. It is also possible to eliminate the need for a steam reheater by controlling the dehumidifying water injector so that the mixed steam from the dehumidifying water injector and steam from the dehumidifying water injector has a temperature suitable for operating the steam turbine.

〔Example〕

When the equipment of the method of the present invention as shown in Fig. 1 is used, only pulverized coal is used as the steam heater and smelting furnace shaft fuel, and the combustion exhaust gas temperature of the steam heater is set to 600C, a comparison is made. As an example, in the equipment according to the conventional flow sheet shown in Fig. 2, the steam heater fuel is heavy oil, the smelting furnace shaft fuel is pulverized coal, the combustion exhaust gas temperature of the steam heater is 450C, and the air is being blown. The amount of charge to the smelting furnace was 62.6 t/H, and the composition of copper concentrate, the main raw material, was 31% by weight of OU, 829% by weight of Fθ, 24% by weight of Fθ, and 7% by weight of Si0. there were. or,
The produced broken AU of 55% by weight and the amount of steam introduced into the steam heater are also the same at 40 t/h. The results for both sides are shown in Table 3.

Table 3 Example Comparative example Steam heater exhaust gas temperature C600450 Outlet steam temperature 0540 460 Reaction oxygen enriched air Air temperature 460 390 Temperature reduction water injector inlet temperature il: 440 370
Average amount of water injected into the cooling water injector t/HO・8 When the converter is stopped t/H1・9 When the converter is blowing t/HO,5 Temperature reducing water injector outlet temperature When the converter is stopped C386 When the converter is blowing C425 Pulverized coal Heavy oil steam heater used as fuel 9/H1B40 830 smelting furnace shaft used as pulverized coal 9/H20201900 hot air drying stove used amount of heavy oil kg/H80190 steam reheater used tt kg/H60170 amount of oxygen supplied to smelting furnace (9
0%) Nm /H4B00 5060 Reaction air oxygen concentration Capacity % 32.4 33.0 Power recovery amount KW/H67706570 As is clear from Table 3, according to the method of the present invention, the fuel used in the steam heater is solid fuel, and the If the exhaust gas temperature is kept at 600C, which is higher than before, and the reaction air temperature is kept high, the fuel for the steam heater conventionally used in the main smelting furnace auxiliary equipment can be changed from expensive heavy oil to inexpensive fine powder. Not only can it be replaced with charcoal, but it has also become possible to indirectly replace some of the heavy oil used in hot air ovens for drying ore with inexpensive pulverized coal.

In addition, in this operating method, when steam at a slightly lower temperature from the converter waste heat recovery boiler is not introduced before the steam reheater for using the waste steam of the air preheater for power generation, the steam reheater In order to enable stable operation of heavy oil, water is injected into the cooling water injector installed at the steam outlet of the air preheater to lower the temperature. Overall, the amount of pulverized coal used as solid fuel is lower than in the comparative example. 1
The amount of heavy oil used could be reduced by 9/H to 1,050 compared to the increase of 9/H to 960, and the conversion rate from heavy oil to solid fuel in this facility could be significantly increased. Furthermore, in terms of energy economy, oxygen consumption can be reduced by 260 Nm/H and power recovery can be increased by 200 KW/H, making it economical in terms of price.

〔Effect of the invention〕

As explained in detail above, according to the present invention, in the smelting furnace accessory equipment for processing sulfide ore, it is possible to use solid fuel as fuel for the steam heater instead of conventional liquid fuel, and the temperature of the combustion exhaust gas can be reduced. By increasing the temperature, the equipment cost of the steam heater can be reduced, and not only can the fuel of the steam heater be replaced, but also the liquid fuel used in the drying equipment can be indirectly replaced with solid fuel.

In addition, a cooling water injector is installed at the air preheater outlet to enable stable combustion in the steam reheater when steam temperature at the air preheater outlet rises and steam is not introduced into the converter system. Since the steam temperature can be lowered by injecting water into the reactor, the overall temperature of the reaction air in the smelting furnace can be raised to maximize energy economy.

[Brief explanation of drawings]

Figure 1 is a relationship diagram of smelting furnace ancillary equipment in the operating method of the present invention, Figure 2 is a relationship diagram of conventional smelting furnace ancillary equipment, and Figure 3 is a diagram showing the amount of oxygen used in the smelting furnace and the amount of pulverized coal supplied. Figure 4 is a diagram showing the relationship between the amount of oxygen used and the amount of waste heat boiler man-log gas, and Figure 5 is also a diagram showing the relationship between the amount of oxygen used and the amount of steam generated by the waste heat boiler and the amount of recovered electricity. Figure 6 shows the relationship between 4750 Nm /
The relationship between the steam temperature at the outlet of the steam heater and the steam temperature at the outlet of the air preheater and the air temperature at the outlet of the air preheater, as well as the relationship between the steam temperature at the steam heater outlet and the steam temperature at the steam heater outlet when steam is introduced into the converter boiler. It is a figure showing the relationship between steam reheater heavy oil consumption.

Claims (2)

[Claims] (1) A waste heat boiler that recovers heat from the exhaust gas of a smelting furnace that uses dried sulfide concentrate as the main raw material and uses solid or solid and liquid fuel as auxiliary fuel, and steam heating that heats the steam of the waste heat boiler. an air preheater for preheating the oxygen-enriched reaction air supplied to the smelting furnace by the steam heated by the steam heater, and a generator for operation driven by the steam that has passed through the air preheater. Smelting furnace accessory equipment comprising a steam turbine and drying equipment for drying the sulfide concentrate, which is supplied with combustion exhaust gas from the steam heater and is reheated by hot air produced by burning fuel in a hot blast furnace. The fuel used in the steam heater is solid fuel combustion or mixed combustion of solid fuel and liquid fuel, and the combustion exhaust gas temperature is 500 to 650°C.
A method of operating a smelting furnace ancillary equipment characterized by operating it so that (2) A waste heat boiler that recovers heat from the exhaust gas of a smelting furnace that uses dried sulfide concentrate as the main raw material and uses solid or solid and liquid fuel as auxiliary fuel, and steam heating that heats the steam of the waste heat boiler. an air preheater for preheating the oxygen-enriched reaction air supplied to the smelting furnace by the steam heated by the steam heater, and a generator for operation driven by the steam that has passed through the air preheater. Smelting furnace accessory equipment comprising a steam turbine and drying equipment for drying the sulfide concentrate, which is supplied with combustion exhaust gas from the steam heater and is reheated by hot air produced by burning fuel in a hot blast furnace. The fuel used in the steam heater is solid fuel combustion or mixed combustion of solid fuel and liquid fuel, and the combustion exhaust gas temperature is 500 to 650°C.
Further, a cooling water injector is installed at the steam outlet of the air preheater,
A method for operating a smelting furnace ancillary equipment, characterized in that when steam generated by a converter exhaust heat recovery boiler is not introduced, water is injected into the cooling water injector to lower the temperature of the steam supplied to the steam turbine.