Refrigerant substitution technology of foaming agent for refrigerator
Development and comparison of
Yang Yibo China Household Appliances Research Institute (100037)
Through the investigation of CFC substitution technology routes in refrigerators in Europe, America and Japan, various implementation schemes of substitution technology are compared, and suggestions on CFC substitution schemes in refrigerators in China are put forward.
Keywords: foaming agent refrigerant refrigerator replacement technology
After we visited the CFCs substitution technology of refrigerators in Europe, the United States and Japan, we compared various substitution technologies. Finally, some suggestions on the replacement technology of CFCs in China are put forward.
Keywords: foaming agent refrigerant refrigerator replacement technology
In order to implement the multilateral fund project of establishing CFCs substitution testing and evaluation promotion center in the household refrigeration industry of the United Nations, China Household Electrical Appliances Research Institute conducted a five-person investigation team headed by Jiahua Yang in June 5438+0996+065438+ 10 and June 5438+0997 respectively, and went to some refrigerator, compressor and foaming material factories in Europe, the United States and Japan and a number of research and testing units to study foaming agents and foaming materials for refrigerators. As the overall situation of the investigation has been introduced in the special article (published in the second issue of this journal 1997), this article will not repeat it, but only make a shallow comparative analysis of the implementation of refrigerator replacement technology in these countries for reference.
Development and comparison of alternative technologies for refrigerator foaming agent F 1 1
The scheme of 1. 1 cyclopentane replacing F 1 1 has been widely adopted by various countries.
At present, there are two main substitutes for refrigerator foaming agent F 1 1, namely HCFC 14 1b and cyclopentane. The former is the main scheme adopted by the United States, but because the ODP value of 14 1b is 0.1and the GWP value is 0. 12, it cannot be used as the final substitute for CFCs. Moreover, when 14 1b corrodes the ABS plate of refrigerator liner, it is necessary to adopt double-layer arched extrusion plate or modified ABS plate, which will increase the operating cost. In addition, the foam shape stability of 14 1b is poor, and the process needs to be improved to ensure its use. 14 1b was banned in 2003. Therefore, some European countries, first of all Germany, adopted cyclopentane scheme, and then some Nordic countries such as Italy, Netherlands, Britain, Sweden, Denmark and Norway also adopted cyclopentane scheme. So far, these countries have used cyclopentane to replace F 1 1 for many years, and they have rich practical experience in technology. They are considerate in energy consumption, cost, production and use safety, maintenance and other aspects of refrigerators, and their production automation level is very high. The most typical factory is Dr. Tianjin Siemens refrigeration appliances. The factory has an annual output of 2 million refrigerators, and the original consumption of F 1 1 is 6,500 tons. Since 1993 changed to cyclopentane, accurate measures such as ventilation, isolation, explosion prevention, anti-static and alarm have been taken in production safety, and 5 million refrigerators foamed with cyclopentane have been produced without any problems. In Japan, although the main scheme was 14 1b in previous years, many refrigerator factories have changed to cyclopentane scheme in recent years. The three refrigerator factories we visited, Panasonic, Hitachi and Sanyo, also established cyclopentane foaming production lines. In China, the joint ventures Wuxi Panasonic Refrigerator Factory and Boxiang Refrigeration Co., Ltd. adopted cyclopentane foaming production line; Xinfei introduced the cyclopentane foaming production line of German Hanna Machinery Company, achieving an annual production capacity of 600,000 units; Kelon and Haier have both realized the transformation of cyclopentane foaming production line. In the United States, due to the energy law that 14 1b foam is more energy-saving and safer than cyclopentane foam, the restrictions on flammable substances by security agencies, and domestic economic protection, cyclopentane scheme cannot be adopted. However, the United States has not restricted the import of cyclopentane foaming refrigerator on the grounds that flammable cyclopentane foaming agent can not pose a danger to safety in refrigerator foam. It can be concluded that cyclopentane replacing F 1 1 is a long-term scheme, which can be recognized and widely adopted by all countries in the world.
The technology of replacing F 1 1 with 1.2 cyclopentane is also developing.
Although cyclopentane substitution scheme is widely used, the scheme using n-pentane and isopentane has been implemented because of its higher thermal conductivity than 14 1b, limited resources and higher price. N-pentane and isopentane have good foaming strength and fluidity. Although their thermal conductivity is high, they are rich in resources and low in cost. Doctor-Siemens refrigerator factory is using a mixture of n-pentane and isopentane instead of cyclopentane as foaming agent, which can reduce the cost by 8%. For the combination of n-pentane foaming and R600a as refrigerant, the energy consumption of refrigerator can be kept at the level of F 1 1+R 12. This is gratifying information for our country, because cyclopentane is imported at present, and the price is very expensive, and our country is rich in n-pentane and isopentane resources, so we should try our best to develop this scheme.
The cyclopentane production line in European factories adopts local essential explosion-proof and circulating ventilation in the whole workshop, which has high cost. The cyclopentane production lines of Panasonic Hitachi, Sanyo and Wuxi Panasonic in China adopt a closed explosion-proof safety system with centralized configuration of the mixing section, box and box door foaming machine, but the whole workshop has no explosion-proof ventilation facilities, which is low in cost and easy to maintain. This has certain reference significance for the new cyclopentane production line.
1.3 Other promising long-term substitutes besides cyclopentane
Although cyclopentane replacing F 1 1 is a long-term alternative with zero ODP, the cost of producing 1 10,000 refrigerators has increased in 7 yuan due to the large investment brought by safety explosion-proof facilities, which is difficult for small and medium-sized enterprises with weak economic strength to popularize. For the United States, a country with strict security requirements, this scheme cannot be adopted at present. And 14 1b stopped using in 2003. Therefore, they are developing alternatives to 14 1b, including HFC236, 365mfc and 245fa. At present, the first two kinds can not provide enough experimental research and toxicity test, but 245fa has made rapid progress. Bayer, the first company to obtain the patent, has sold it to the United States, and the patent was developed and studied by the Fluorination Department of the Engineering Materials Department of the company. Now the United States will provide 245fa to Japan's Xu subsidiary to develop 245fa combined polyether. Lian Xin Company has a pilot plant, which can produce 20 million pounds in 2000, but the price is four times that of141b. The performance of 245fa is good, the ODP value is zero and the GWP value is 820. At present, it has passed the toxicity test, is nonflammable, does not corrode the ABS material of the refrigerator, has a thermal conductivity equivalent to 14 1b, is slow in aging, is more stable than 14 1b, and has a strength equivalent to F 165438+. Japan's Xu subsidiary has done a lot of experiments on the preparation of 245fa polyether in refrigerator foaming. It should be said that replacing 14 1b will be very promising, and the key is its price. If the consumption has a certain economic scale, it is possible to reduce the price by 14 1b compared with the increased cost due to the need to use anticorrosive liner materials. For such materials, we should actively and quickly master the application technology and strive for market use at the same time, so as to promote the formation of a reasonable scale of production economy and achieve the purpose of wide popularization and use.
In addition, cyclopentane is not only used in Europe, but the scheme adopted by small and medium-sized enterprises is more flexible, depending on various prices in the market. For example, Frigor refrigerator factory in Denmark has an annual output of 60,000 refrigerators. Because 134a is abundant in Europe and low in price, 134a is used as foaming agent, and the special Eacy Froth TM mixer made in Conon of Samos is used as foaming agent for freezer, and the effect is good.
2 refrigerator refrigerant R 12 development trend and alternative technology comparison
2. 1 At present, the main replacement of R 12 is R 134a.
In fact, in Europe, as early as 199 1, a lot of experiments were completed for the replacement of R 134a, and 1992 adopted R 134a. However, R 134a scheme not only has the advantages of zero ODP value, nonflammability and mass production of R 134a, but also brings a lot of troubles. Firstly, the energy consumption of refrigerator will increase after adopting R 134a; Because it is insoluble in mineral oil, it needs to be changed to ester oil as lubricant, and because of its water absorption, it is easy to cause ice blockage in the system, so it is required to strictly control the moisture and mineral oil content of parts in the production process, which leads to production trouble and increased cost. It is also necessary to produce a special compressor, using accessories insoluble in R 134a, and requiring the compressor to have a higher COP value to make up for the increase in energy consumption, which will increase the production cost of the compressor; The compressor used in R 134a has strict requirements in production, and it is required to prevent leakage after forming the refrigeration system of the refrigerator. Fault maintenance leads to an increase in maintenance costs and a decline in performance. For example, Whirlpool Refrigerator Factory in the United States has done a lot of experiments to produce refrigerators with R 134a as refrigerant, including model tests of capillary blockage caused by R 134a. For another example, the three refrigerator factories we visited in Japan, Panasonic, Hitachi and Sanyo, all set up special laboratories to analyze moisture, grease and impurities, and conduct regular sampling inspection. In the production process, the copper tube used in the refrigeration system needs to be sealed with nitrogen, and the molecular sieve needs to be stored in a special dryer or packed with plastic, and it needs to be installed in the system within 20 minutes after unpacking, which leads to an increase in operating costs. For our country, it should be said that it is difficult to adopt the scheme of R 134a. First of all, the equipment investment is large, the vacuum pumping system should use special equipment and special system, and the filling equipment should also be special, so it can not be used concurrently with the original production line equipment; Secondly, the analysis equipment of oil, water and impurities in the production process is not uniform and needs to be invested and purchased; Third, production management needs to be further improved to strictly control the process, and the long-term stability of management needs to be improved; Fourthly, the R 134a material has not formed a scale in China, so it needs to be purchased at a high price, which increases the cost; Fifthly, in order to adapt to the maintenance of R 134a, maintenance outlets need to train personnel and put in special maintenance equipment. If in-plant maintenance is adopted, it will increase the transportation cost and bring inconvenience to users. In all these cases, it should be said that the alternative of R 134a is not desirable for our country. However, the scheme of R 134a has become one of the main alternatives in China at present. There are four main reasons: First, the R 134a compressor production line has been introduced into China and has a certain scale; Second, there is no other scheme for frost-free indirect cooling refrigerator; Third, meet the needs of exporting to the international market; Fourth, in order to strive for market demand and eager to get on the horse. In fact, R 134a scheme is too difficult for small and medium-sized enterprises.
2.2 The substitution of R600a for R 12 has developed rapidly.
When some European enterprises realized the troubles caused by the R 134a scheme, with the support of Greenpeace, they turned to the alternative scheme of R600a in order to quickly complete the replacement schedule of R 12. This scheme has many advantages: ① raw materials are easily available and can be produced in oil refining industry; ② Low price; ③ The lubricating oil can be original R 12 lubricating oil; (4) Each refrigerator has a small amount of filling, and generally the contents of two lighters are enough; ⑤ Low operating pressure and low noise, which can reduce energy consumption by 5 ~10%; ⑥ODP value and GWP value are both zero; ⑦ No special requirements for system materials; ⑧ Compared with R 134a, the control of production process is less strict and the maintenance cost is lower. Pet-name ruby after maintenance will not bring any difficulties and quality impact to maintenance; Attending the vacuum pumping system in the production process can borrow the system of R 12, without special lines. It has four main disadvantages: ①R600a is flammable, which may cause the danger of explosion if it leaks when used in large refrigerators; ② Safety and explosion-proof measures need to be put into production; ③ Frost-free indirect cooling refrigerator has no better refrigerator design scheme using R600a; ④ When the working pressure is low, the R 12 compressor can no longer be used, and the R600a compressor with double cylinder capacity should be produced.
Compared with cyclopentane, the reconstruction cost of R600a alternative is much less, because the special filling machine for R600a has been produced, and explosion-proof measures have been taken into account, so other explosion-proof measures are not needed in the workshop. It is not technically difficult to produce a compressor suitable for R600a, so Europe quickly formed a large-scale production capacity. It is not difficult for European refrigerator factories to quickly switch to R600a scheme, and it is developing rapidly. The most typical one is Marcstad refrigerator factory of Lido Group in Sweden, with an annual output of 300,000-400,000 refrigerators. In 1996, the refrigerator output of R600a scheme is 30%, and that of R 134a scheme is 70%. By 1997, they plan to reverse this ratio. Strict ventilation, isolation, explosion-proof, anti-static and alarm measures have been taken in safety production, and the experience is rich. Another example is Osby Refrigerator Factory, a small refrigerator factory in Sweden, with an annual output of 50,000 units. Three years ago, Tectrode Company of Denmark was invited to transform the production line, adopting cyclopentane and R600a technology, and the cost of transformation was about 6,543.8+0,000 USD. However, the United States has strict control over the R600a scheme. Recently, UL of the United States has stipulated the application of flammable substances. For example, the consumption of each refrigerator using R600a should not exceed 50 grams. If it exceeds 50 grams, strict fire and explosion prevention measures must be taken and the situation should be reported to the US Environmental Protection Agency for approval before production. In China, many refrigerator factories adopt R600a scheme, and manufacturers also have this desire and requirement. At present, domestic R600a needs to be imported at a high price, and chemical plants such as Tianjin and Nanjing are ready for commercial production. On the other hand, the compressor suitable for R600a has not formed the production scale, which is also the main reason why the R600a scheme cannot be popularized in China. At present, China is in the stage of trial production and introduction. Some factories, such as zanussi in Tianjin, Jiaxi Bella in Zhejiang and Huangshi in Hubei, have started trial production of R600a compressor and are setting up production lines. It seems that it will take a long time to adopt the R600a scheme on a large scale, and the scale of R600a should be promoted as soon as possible.
2.3 Progress and application prospect of the scheme of replacing R 12 with mixture
As a safe and efficient refrigerant, R 12 has been used in refrigerators for more than 60 years and is the best refrigerant after years of screening. Therefore, when it is found that R 12 has seriously damaged the ozone layer, it is difficult to find a pure working medium with the same performance as R 12 to replace R 12, which can be said to be impossible to find again. The current alternative can only be said to be as close as possible to r66. Therefore, people look for substances with similar performance to R 12 on mixed working fluids. In recent years, there are many kinds of mixed refrigerants, which are basically divided into three categories: one is to combine HFC and HCFC with mixed refrigerants of various proportions; The other is the recently developed hydrocarbon mixture, such as the mixture of propane and isobutane introduced by CalorCas Company of the United States, which can replace R 12 and R 134a with ODP=0 and GWP < 15, and is entering the trial-production stage. As far as refrigerators are concerned, there are no commercial products using hydrocarbon mixtures. The representative of the first mixed working medium is American DuPont MP39, which is made of R22, R 152a, R 124 at the ratio of 53%, 13% and 34%, and belongs to the mixed working medium of nearly * * *. THR0 1 developed in Tsinghua University, China is a binary mixture of R22 and R 152a, with ODP < 0.03 and GWP.