In recent years, countries in the aspect of energy conservation and emissions reduction requirements increasingly improve and strictly enforce, therefore many people think that: the application of the cupola have been declining, replaced by induction furnace is an irreversible trend. "Foundry industry" twelfth five-year "development plan" and "the casting industry access conditions," clearly put forward for 3 t/h or less small cupola to take out the policy. In reality, however, a lot of 10 t/h or large cupola was also banned, along with all the cupola will be fully out of the wind in the field of casting is also increasing.

Cupola is really good for nothing? Where it was mass criticism? Facing a comprehensive ban, cupola who provoked in what aspects?

Cancel the cupola does not affect the importance of smes

To abolish all potential trend of cupola, China foundry association, senior consultant 李传栻 but don't think so: "if the cast iron smelting equipment make a comprehensive analysis, the development of cupola with electric furnace irreplaceable characteristics, and from the perspective of low-carbon economy, cupola this tradition of smelting equipment still has strong vitality and broad space for development."

李传栻 analysis thinks, medium and small foundry enterprises use induction furnace instead of cupola is very appropriate; But, foundry industry is high energy consumption industries, enterprises in the future will certainly to clustering, large-scale development, the production of medium and small foundries in the share of casting production will be more and more small. He said: "at present, the industrial countries in the cast iron smelting equipment used in the industry, if in terms of the number of furnace, induction furnace than cupola, of course. But most of cupola is large, and long campaign life, production capacity is very strong, if in terms of iron production, and is still the majority of cupola melting." That is to say, in the cast iron smelting, cupola and electric furnace will always coexist, and the amount of cupola melting than the amount of smelting electric furnace.

According to:

1, five years from 2003 to 2007 in the European Union countries the dosage of the foundry coke has remained at around 1.5 million t, and a slight growth, to illustrate the application of cupola did not decline; Iron liquid production at present, the European Union, 50% is made up of cupola melting.

2, 2006, the French production of various kinds of iron in the cupola melting equipment (including double) accounted for 60.6%.

3, the German production of cast iron parts in each year about 3.7 million t, namely each year to 5 million t iron liquid, of whom 65% cupola melting; And Germany in the existing 50 sets of cupola melting rate is the largest of 90 t/h, a total of 5. The five sets of cupola melting iron liquid volume reached 1.75 million t every year.

4, according to the casting of the cupola manual (version 6) published by the listed data, the United States for cupola melting equipment production of all kinds of cast iron is still in the cast iron parts accounted for about 70% of the share in total. A company using a 105 t/h cupola to production of automotive brake discs.

Rational look at future A comprehensive understanding of cupola

Current conditions in our country, with cupola melting equipment production of cast iron parts in more than 70%, thus correctly understanding and mastering the cupola, to improve the quality of cast iron pieces in metallurgy, reduce production cost, and energy saving, emission reduction, is essential, also is our country from the casting powers to the casting powers must solve one of the topics.

Cupola in the casting industry has a pivotal role, face clamp down on the most important issue in the embarrassing concentrated in both large energy consumption, serious pollution, and many local governments forced electric furnace to replace the cupola is also at the two points. But the fact is true?

Cupola filled carbon consumption

, vice President of the original mechanical science research institute, director of Chinese mechanical engineering society honor, casting association, senior consultant in the room are said in an interview: "electric furnace using electricity, using the secondary energy; and many of the cupola is using heat from the burning of coal, it is an energy. Thus, in contrast, the energy consumption of electric energy consumption should be combined with the energy to secondary energy consumption at a time. So, the accounting unit price than, than cupola furnace doesn't necessarily low energy consumption."

李传栻 worked in his study energy consumption contrast both cupola and electric furnace has been calculated in detail, the results also confirmed this claim. In theory, the 1 t metal furnace charge from room temperature 24 ℃ to heat up, into 1550 ℃ of iron liquid will need 1322.6 MJ heat, this is basically will not change. Such as no waste gas waste heat utilization, cupola melting cast iron, used for melting iron material and make the energy of the liquid iron overheating, generally only coke to about 40% of the total energy, energy efficiency is quite low. Coke calorific value calculated on 30 MJ / ㎏, the smelting iron per ton of energy consumption is about 3750 MJ. Amount of liquid iron consumption per ton of coke average about 125 ㎏.

With medium frequency induction furnace melting crucible type, the thermal efficiency can reach 70%, such as iron liquid power consumption by an average of 600 kW per ton, h calculation, the results showed that 1 kW, h. energy equivalent to 3.6 MJ, melting energy consumption of per ton iron liquid for 2160 MJ. From the comparison of energy consumption, the energy consumption of the induction furnace melting cast iron is only 57.6% of the energy consumption of cupola melting. Only from electric heat equivalent to consider, of course, is far better than that of the cupola induction furnaces.

But if considering the electricity is secondary energy, and, most of the current electricity from coal conversion; According to the carbon consumption to evaluate, the situation is very different.

Power plant coal consumption of electricity output per kW, h averaged 0.32 ㎏ of standard coal. By this reckoning, induction furnace smelting iron liquid carbon consumption per ton of 192 ㎏ of standard coal, not including transmission process about 5% of all kinds of losses.

Cupola melting, the amount of liquid iron consumption per ton of coke for an average of 125 ㎏. Fixed carbon content is 84% of coke, calorific value and roughly of standard coal. By this reckoning, only 125 ㎏ liquid iron carbon consumption per ton of standard coal, about 34.9% less than with induction furnace smelting.

Germany has a famous induction furnace production company doing all kinds of melting furnace energy consumption contrast (taking into account the efficiency of the furnace and the kind of energy), the conclusion is: 1 t per smelting iron liquid energy, about 6200 MJ, intermediate frequency electric furnace cold wind about 5300 MJ cupola, hot air cupola about 4400 MJ; Hot air cupola is medium frequency induction furnace energy saving more than 40%.

Thus, the use of cupola melting, carbon consumption is much less than with induction furnace smelting.

Rowan waveso a secondary energy, is, of course, made of refined coking coal, however, a by-product of coking coal tar is an important chemical raw materials, coke oven gas is of high quality fuel, the value is higher than coke. From the energy comprehensive utilization seems to coke as fuel, with cupola melting cast iron, can yet be regarded as a desirable option, of course, and are beneficial to the state and enterprises.

Machinery institute of science in anhui province, chief engineer, casting association, wear-resistant materials and casting branch secretary-general song also shows that the point of view: it is the electric furnace melting and cupola melting are two different concepts, the former is a physical phenomenon, the physical and chemical phenomena. Cupola in the process of smelting, can be helpful for better combustion chemical. In addition, the sensible heat and latent heat in cupola gas accounted for about 40% ~ 45% of the coke used in total energy, if fully take advantage of the quantity of heat, more can reflect the advantage of cupola melting. At present, in terms of use of cupola gas heat, there have been many kinds of effective methods. "Of course advantages not only in the cupola, abolish all cupola is premature." Song said.

Contrast, it seems, in cupola blustering criterion, energy consumption is a grievance.

Derive the cupola furnace charge adaptable of metal

In addition, the cupola burden on metals are more strong ability to adapt.

In recent years, in order to realize the lightweight equipment, various industries, especially in automobile industry, the steel, alloy steel the proportion of more and more. General motors, for example, steel, medium carbon steel used in 2003 accounted for 65%, down to 10% in 2010. This from resources make full use of lightweight, all kinds of equipment, technology progress and so on, it seems, is a good thing, of course, and this trend will continue in the future. However, the increasing of the alloying elements in steel scrap is to cast iron industry has brought many problems. Induction furnace melting cast iron, because they had no metallurgical reaction process, the amount of casting pig iron in the furnace charge to limit, scrap share will increase, and the alloy elements in the steel on the performance of the cast iron (especially the nodular cast iron) but mostly have a negative impact; In cupola melting process, on the other hand, easy removal of low boiling point elements, such As Pb (1755 ℃), Sb (1640 ℃), Bi (1481 ℃) and Te (989.8 ℃), the As sublimation (615 ℃), Cd (767 ℃), zinc (419.5 ℃), etc., with induction furnace smelting is relatively difficult to removal, which is easy to show its negative influence.

Derive the alternative fuel cupola innovation vast space

Current situation of most in cupola in addition to the "big" energy consumption, pollution and serious problem. The facts? It whether there is any progress space?

Qingdao green power environmental protection equipment co., LTD., said Joe cupola main pollution emissions of soot, cinders and heat. Soot pollution of air, slag pollution of land, the deterioration of heat addition to the work environment, a stream of rising or smoke suspended in the air diffusion source of power.

These contaminants related to its conventional fuel coke cupola. Cupola pollutants emissions and furnace type, working system, furnace charge, coke, refractory materials, melting operation and other factors. According to the product requirements, correct selection, optimizing the combination of these factors, can maximum limit reducing emissions of pollutants. Which can not only reduce the pollution degree of cupola, can also reduce the burden of pollution prevention, as well as improve the quality of molten iron and the effect of saving energy and reducing consumption.

Since cupola pollutants associated with coke, so, do not use coke, cupola can also work as usual? The answer is yes. 李传栻 said the cupola in saving energy and reducing consumption in the use of alternative fuels, there is a great innovation and development of space.

1, the application of the biological carbon block is in the research and development

Waste sawdust, tree bark, kaoliang stalk, leaf, such as waste, is carbon material, if use, is not only a renewable resource, but also with given waste. Many countries have set out to discard this kind of material biological carbon block, being used as fuel in cupola, instead of coke.

2, USES the high ash content of coke and reduce the production cost

Cupola with air cooling operation conditions, with low ash, high fixed carbon foundry coke, in improving the furnace temperature, ensure the quality of metallurgy of cupola melting, it is very necessary. Coking coal resources are rich in our country, is currently the coke yield of the highest in the world, but China's coking coal in the "grey" content is high, poor "wash", refining and low ash content of coke process trival, high cost. If we can be on the basis of strengthening cupola melting, the solution to this problem, the meaning is profound, it will also further enhance the competitive ability of cupola.

3, the foundry formed coke

Formed coke for blast furnace ironmaking is already widely attention, casting industry formed in coke instead of coke in a cupola assignment, now in addition to Poland and Korea more successful, mostly is still in experiment and explore. In view of the domestic situation, the key to application formed coke is formed coke factory to strengthen cooperation with casting enterprises, research institutes, and optimize the production technology aspect of formed coke. Foundry enterprises should fully grasping the characteritics of formed coke in terms of use.

4, the application of anthracite coal

Anthracite coal density higher than that of coke, such as replacing parts of the coke in the same weight and volume of the fuel in the furnace of smaller, more conducive to heat the metal furnace charge transfer. In cupola with anthracite coke instead, however, should be paid attention to: choose low volatile anthracite. Such as volatile matter in coal is high, should first be calcination process. Not a substitute for coke bed, can only be used for coke, dosage is 10% ~ 20% in general.

Cupola is always in the improvement and development

Has the shortcomings, right face and correct it, is the rational approach. Abolish all while killing of cupola pollution problem in the short term, but for long-term development in foundry industry is in the what's more, things are changing all the time development, the cupola is always in the improvement and development. Induction furnace has just come out in the 1960 s, cupola pollution problem difficult to solve, so electric furnace has been widely promotion; Later, cupola emissions can be strictly controlled in 30 mg/m3, even under 10 mg/m3, both in the industrial developed countries to get the reasonable division of labor and the application. Of course, here said the cupola is refers to the cupola with dust removal device.

In all kinds of smelting technology and equipment to the development of the present, also in cupola and perfected constantly absorbing new technology, and realize the modernization, large-scale, long campaign life and the diversification of fuel, and the sensible heat and latent heat in furnace gas utilization and waste gas, soot governance innovation constantly, which can give full play to its production cost is low, the metallurgy quality advantage.

In recent years, the cupola smelting in structure and related technology development, mainly has the following several aspects:

Type furnace structure: two rows of big span tuyere blast; Water-cooled cupola. Avoid focal cupola; Show heat and latent heat in the furnace gas recycling system, etc.

Blast: oxygen enriched air supply; Take off your wet air supply; Since the tuyere into gas and coke at the end of the auxiliary fuel, etc.

Job control, air volume and air pressure control; Furnace gas composition control; Iron liquid temperature, and the composition control; The dynamic thermal analysis control; Smelting process of computer control, etc.

: energy saving and emission reduction furnace gas sensible heat and latent heat of use; Exhaust harmless; The improvement of dust removal system; The application of alternative fuel; Slag recycling, etc.

The soot purification: high temperature smoke from cone absorb trap, make the cap and feeding mouth is in a state of negative pressure, avoid dust spillover; After high temperature flue gas duct into one flow cooler before entering the multi-tube cyclone water cooler, the temperature can drop to about 100 ℃, finally entered the room temperature bag filter purification, and then after desulfurization spray tower desulfurization emissions can be up to standard.

Waste heat recycling: make full use of smelting equipment loss of heat energy, through the water – water exchange, make the water temperature of 40 ~ 50 ℃, can be used as a worker all the year round, such as bathing water to wash your hands.

Should abolish all cupola? Must have writing at this point, the reader has his own thinking. Cupola has its own limitations, but its importance and the development prospect to be reckoned with, cupola is to stay, should be more rational. (written/Du Yun, technical guidance/test, WenPing, plan and audit/nan) written: Du Yun

Technical guidance: test, WenPing

Planning and review: her nan