Analysis of heat treatment technology development and heat treatment industry market (3)
2 .1.2.4 Development of energy-saving equipment and processes: The development of energy-saving equipment and processes is a very effective energy-saving measure. In recent years, continuous furnaces have replaced cycle furnaces with great potential for energy savings. A high-efficiency heat exchanger is used on the combustion furnace to preheat the air, and the combustion coefficient (α) is reasonably controlled in the range of 1.1 to 1.3, and the burner and the radiant tube with the honeycomb type regenerator device and the lateral combustion are promoted to achieve good energy saving. effect. From the design of the furnace, the heat dissipation of the furnace has a great relationship with the surface area of ​​the furnace. Thus, the circular section of the furnace can be 14% smaller than the surface area of ​​the rectangular section, and the temperature of the outer casing can be reduced by 10 °C, so that the heat dissipation through the furnace wall is reduced by 20 %. For this reason, the Japanese sealed multi-purpose furnace and push-rod continuous furnace have been changed to a circular cross section. It has been reported that Japan Tonghe Mining (formerly Tokyo Heat Treatment in Japan) will carry out energy-saving renovation of carburizing, quenching, cleaning and tempering push rod production lines 20 years ago, changing the pre-cleaning to combustion degreasing, and the heat of degreasing exhaust gas is used as a tempering furnace. Part of the heat source uses the atmosphere discharged from the carburizing furnace as the heating of the degreasing furnace and the lye cleaning tank and the quenching oil. Such waste heat utilization reduces the fuel cost by 40% and improves the environment. In China, the energy-saving potential of equipment is even greater, and it should be paid attention to by heat treatment workers and equipment manufacturers in China. Energy savings bring wealth.
The development of energy-saving heat treatment processes is also an effective energy-saving measure. The implementation of high-temperature carburizing can greatly shorten the process cycle. This work has been carried out in Japan for a long time. Increasing the carburizing temperature from 930 °C to 1050 °C will shorten the process cycle by 40%. However, it is difficult to achieve the limitation of the heating element and the heat-resistant material in the general resistance furnace, and low-pressure carburization in a vacuum furnace, carburization at 1050 ° C is a breeze. Nowadays, acetylene low-pressure carburizing has been matured and applied in production, and a revolutionary breakthrough in vacuum carburizing technology has been realized. Low-pressure ammonia gas can also be used to achieve low-pressure carbonitriding of acetylene, regardless of quality, environmental protection and economics. Carburizing is a surface modification technique that meets future requirements that can be integrated into the production line (discussed below).
Substitution of carburizing and carbonitriding by nitrocarburizing, sulfur-nitrocarburizing and oxynitriding can reduce the process temperature from 850-930 °C to 550-580 °C instead of general gas nitriding. 30 ~ 70h reduced to 1.5 ~ 3h. In addition, the post-forging heat treatment of steel parts, the use of non-tempered steel instead of expensive energy-consuming quenching + high temperature tempering process can achieve energy-saving purposes.
It has been reported that China's electricity consumption per ton of steel is 500-1000 kWh, which is 2-3 times higher than that of the United States, Europe and Japan. From the above analysis, the potential for developing energy-saving equipment and processes is great, and the outlook is optimistic, but we must make efforts. .
2.2. Current situation of China's heat treatment industry and the gap with foreign countries
2.2.1 Current status: The basic situation of China's heat treatment industry is compared with that of the United States (1996) and Japan (1998). The situation in China is commonly published in general magazines. It is actually the situation in China in the mid-1990s. The situation in China is taken from metal heat treatment in 2005. It is the Chinese heat treatment industry association Professor Fan Dongli. According to about 20 industries in 2003. The estimated estimates based on urban surveys seem to be quite optimistic.
At present, there are about 15,000 heat treatment plants, branch factories, workshops, joint-stock companies and private heat treatment enterprises in the national all-round enterprises, of which about 12,000 are full-scale enterprises, accounting for 80%, and about 3,000 are private and joint-stock enterprises. The total number of heat-treating employees (calculated by 25 people per household) is about 370,000, of which about 30,000 and 33,000 are technicians and managers, accounting for 8% and 9%. The national heat treatment heating equipment is about 150,000 units (one standard unit is calculated at 75KW), and the installed capacity is 11×106kW. The calculated annual production capacity of national heating equipment is nearly 45×106t. The calculated total power consumption is 9.9 x 109 kWh. The annual turnover of the national heat treatment is about 31 billion yuan. The calculated annual labor productivity of China is 87,000 yuan per person year, which is more than the 60,000 yuan/person-year level in the later period of the ninth five-year plan of China, but still 1/10 of the 1996 level in the United States. In terms of energy utilization calculation, the average unit heat consumption of the national heat treatment is about 730 kWh/t (the actual annual heat treatment production in the country is 13.5×106t), and the “10th Five-Year†target of the average electricity consumption of large and medium-sized cities in 2005 is expected to reach 500 kWh/t. achieve.
Domestic calculation of privately-owned joint-stock enterprises specializing in heat treatment: the number of enterprises is about 3,000, and the average annual turnover of each enterprise is 2 million yuan. The annual number is 6 billion yuan, accounting for 20% of the total heat treatment of the country. This ratio is greater than 10% in the United States (1996) and less than 30% in Japan. In addition, the number of employees per company is 10 to 12, and the total labor productivity is 200,000 yuan / person-year - 16.7 million yuan / person year, which is 1/4 to 1/5 of the United States (1996). It is estimated that the number in Shanghai will be higher. This is only a reference for the calculation of investment and income.
The situation in Shanghai is based on the relevant article in 2000: There are more than 6,500 heating furnaces in the city with an installed capacity of 360,000 kW. The annual electricity consumption is 300 million kWh, and the annual heat treatment weight is about 600,000 tons. According to this calculation, the electricity consumption is 500kWh/t, which ranks first in the country and has reached the goal of China's “10th Five-Year Planâ€. It is estimated that there will be a decline in the past two years. However, this figure is still far from the advanced energy consumption (356 kWh/t) introduced by Holcroft equipment reported in the 1997 Foreign Metal Heat Treatment magazine. Of course, it should be noted that I estimate the average value, and the value of the advanced equipment is a single piece of data. This is for convenience only, and the factors affecting energy consumption are multifaceted. It is reported that the energy consumption in European countries is 400 degrees/t, and that in Japan is 300 degrees/t (the number of years is unknown).
2.2.2 Status and gaps of heat treatment equipment
China's heat treatment furnaces are mainly electric furnaces (more than 90%), but they have the disadvantages of high energy consumption, low thermal efficiency and poor performance. The heat treatment equipment currently used in many production plants was also manufactured in the 1960s and 1970s, and has not completely escaped the state of the fifties. 70% of the heat treatment equipment is heated in the air, and the controlled atmosphere heating and vacuum heating only account for about 5%.
According to the number and composition table of heat treatment resistance furnaces in 1985, the proportions of general box furnaces, salt bath furnaces and well furnaces (including well type carburizing furnaces) were 35.56%, 21.31% and 21.30%, respectively. In addition, according to the recent equipment statistics of the Shanghai heat treatment industry, the proportion of general box furnaces, salt bath furnaces and well furnaces is 40%, 5.55% and 29.11% respectively. It can be seen that in the main heat treatment equipments in China, the proportions of general box furnaces and well furnaces have not changed much in the past 20 years (the salt bath furnace has been greatly reduced due to the ban of BaCl2 in recent years). The obsolescence of the equipment is evident. In addition, the proportion of Shanghai vacuum furnaces and controlled atmosphere furnaces increased to 3.67% and 8%, totaling 11.67% (higher than the national level). Although it is nearly 10 times higher than the 1.68% in 1985, it is far from adapting. The ratio of the requirements of the four processes in the heat treatment industry: carburizing / carbonitriding accounted for 20%; quenching in 20% in neutral atmosphere; 15% quenching in vacuum; annealing / de-stressing 10%, others such as induction heat treatment Nitrogen, brazing, salt bath heat treatment and non-ferrous alloy heat treatment account for about 35% (USA).
The heating of metal in the oxidizing medium will cause serious oxidation loss, and the burning loss in automobile manufacturing will reach 7.5%, that is, 40 to 50 kg of high-quality steel will be lost for each loaded vehicle, and 25 to 30 kg per car, such as cold-rolled steel strip. The intermediate annealing uses non-oxidative heating to save 20% of the material. Less oxidative heating is no longer a problem. Although the domestic automobile, tractor, bearing, spring, fastener industry and key backbone enterprises have less than 80% oxidation heat treatment, the general level is still around 30%. At the same time, domestic equipment is still in manual operation and labor intensive.
The popularity of less oxidative heat treatment technology in the world is the main indicator of heat treatment levels in the 1980s and 1990s. The proportion of non-oxidative heat treatment in advanced industrial countries has reached more than 80%. According to reports, the proportion of vacuum heat-treated parts in European industrial countries in 1980 was 3%, increased to 18% in 1985, increased to 23% in 2000, and the heat treatment specific gravity of controlled atmosphere increased from 19% to 29%, heat treatment in oxidizing atmosphere. The number was reduced from 57% to 7%. In 1985, the US petroleum machinery manufacturing industry had less than 60% oxidation-free heat treatment. At this point, China’s level is still at a very low level.
It is estimated that China will basically complete the technical transformation of “less oxidation†heat treatment as the center in 2010. Then, by 2010, China’s overall heat treatment production level will reach the current level of European and American countries, and it is expected that the backbone enterprises of the department will reach the international advanced level at that time. Level. The demand for advanced heat treatment equipment will be more prominent in more domestic joint-stock enterprises and private enterprises. With the development of molds and the continuous technological transformation of the aviation industry, the demand for high-pressure gas-quenched vacuum furnaces will reach more than 300 per year. By 2010, the demand for 80% vacuum heat treatment furnaces is double-chamber high-pressure gas quenching furnaces above 1000 kPa. Low-pressure carburizing and 2000kPa high-pressure gas quenching production line will be promoted in the automotive industry. It is an important development trend to use gas quenching in an inert gas of 1000kPa～2000kPa after low-pressure carburizing instead of oil quenching. However, domestic equipment manufacturers may not be able to adapt to this requirement.
At the same time, the equipment should be closely monitored for the processing market. China's current heat treatment processing capacity is excessive, and the average utilization rate of general equipment is only 30%. In particular, it is important to pay attention to new heat treatment enterprises. It is not feasible to establish a fixed customer network. In the 2020 Vision of the United States, the ten-year cooperation with customers is typical. The heat treatment from the initial product design stage is included, and the effect of shortening the processing cycle and reducing the production cost of users and heat treatment plants is received.
The gaps in domestic process aid materials, staff quality, management, and human resources are not burdened.
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