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First, vacuum boiler introduction
Vacuum boilers work by utilizing characteristics that vary in boiling temperature at different pressures. At one atmosphere, the boiling temperature of the water is 100 ° C, while at a pressure of 6 mm Hg, the boiling temperature of the water is 4 ° C. The vacuum boiler operates in a pressure range of 20 mmHg to 500 mmHg, and the corresponding outlet temperature is 15 to 80 ° C. Under the pressure of the vacuum boiler, the temperature of the heat medium water rises to a saturation temperature, and Produces steam of the same temperature on the surface of the water.
At this time, circulating water is introduced into the heat exchanger (hot water supply or heating), and the cold water in the pipe is heated by the steam outside the pipe to be warm water and sent to the user, and the water vapor outside the pipe is condensed into water droplets. The return water surface (in the furnace) is heated again to complete the entire phase change cycle.
Second, the background information
The vacuum boiler originated from the invention of the Zurich University of Technology in Switzerland in 1972. According to this invention, Japan developed a vacuum hot water boiler in 1974 and obtained a patent for invention. Since then, this technology has quickly become popular in Europe and the United States and has become a culture of greenhouse culture. New product.
In the 21st century, with China's emphasis on environmental protection, safety, energy saving, manpower saving, reduction of metal consumables and other social development trends and the increasingly mature and perfect vacuum boiler technology, vacuum boilers have become ordinary pressure hot water boilers, pressurized hot water A bright pearl in the hot water supply equipment after the boiler.
Third, the working principle
The vacuum boiler is made of high-purity deoxidized water. It can work in the absolute pressure range of 400.43~94301Pa, that is, it operates under vacuum. The corresponding working temperature is 29-98 °C. Therefore, the vacuum boiler can provide hot water. The effluent temperature is 15 to 90 °C. In other words, the hot water outlet temperature provided by the vacuum boiler can be adjusted within a wide range to meet the needs of users and adjust the fuel consumption. Users can “pay as needed” and save operating costs.
When the vacuum boiler is in operation, the fuel burns out heat energy, the working temperature rises to a set temperature, and the saturated steam of the same temperature is generated on the water surface, and the steam pressure is lower than atmospheric pressure, which is often called negative pressure steam. In the steam, a heat exchanger is installed; cold water is introduced into the heat exchanger. The cold water in the pipe is heated to hot water by the negative pressure steam outside the pipe, and then sent to the water point; the water vapor outside the pipe is cooled and condensed into water droplets and returned to the water surface to be heated, thereby completing the entire cycle. The working system in the vacuum boiler is only used as a heat transfer body, and it does not increase or decrease during the whole cycle. The working fluid in the vacuum boiler is specially treated and can be used for a long time.
Fourth, technical characteristics:
The vacuum boiler has the technical characteristics of “four high, two low and three”: “four high” means high vacuum, high integration, high life and high efficiency. The high vacuum is the life of the vacuum boiler, which is closely related to its high life and high efficiency in the morning. “Two lows” means low emissions and low maintenance. Low emissions reduce harmful pollution and waste heat pollution to the atmosphere. Low maintenance greatly reduces the work intensity of operators and reduces many complicated and repetitive tasks. It is a reflection of people-oriented technology. “Three-way” is intelligent, networked and modular.
5. Low operating costs and investment savings:
1, save fuel
Economical comparison between vacuum boilers and normal pressure boilers
Compared with other types of boilers, vacuum hot water boilers provide the same heat supply because of their high thermal efficiency, and the gas consumption is very economical. When comparing with an ordinary horizontal atmospheric hot water boiler, the energy saving of the entire system should be considered.
The vacuum hot water boiler consumes less gas (m3/h) than the ordinary horizontal atmospheric hot water boiler, such as using 2400h per year to save gas:
5×2400=12000(m3)
If the gas price is 3.5 yuan / m3, the annual savings:
12000m3 × 3.5 yuan / m3 = 42,000 yuan, which shows the energy saving of vacuum hot water boilers.
2, save electricity
The vacuum boiler is equipped with a heat exchanger, which saves a circulating water pump, thus saving electricity. Generally, a 600,000 kcal/h atmospheric pressure hot water boiler consumes about 3kw.h of circulating water pump. If the usage time is the same as above, More power consumption: 3 × 2400 = 7200 (kwh); If the electricity price is 0.6 yuan / KW.h, the annual savings: 7200 * 0. 6 = 4320 yuan
3, water saving
The vacuum boiler has its own medium water, which is injected once, without loss in use, and the medium water is specially treated. It has no oxygen inside, no CO2, no impurities. Long-term use, no need to replace. The atmospheric hot water boiler has a loss of impurities due to the presence of atmospheric pores, which causes impurities to concentrate. The water in the furnace is handled by the user himself. In the process, oxygen and CO2 are mixed in, and there are many impurities and foreign matter in the system, which will be mixed into the furnace. Therefore, the sewage should be drained regularly from the drain valve. For example, a 600,000 kcal/h atmospheric pressure hot water boiler has a water system capacity of 2T, and 4 times of sewage discharge per year. When adding sewage, the cleaning water (about 1 times the capacity) consumes water every year: 2*2*4= 16(t), in addition, can save money on water treatment medications.
4, saving manpower
The vacuum boiler has high degree of automation, small operation and maintenance workload, safe use, few auxiliary equipments, and low requirements, so no professional duties and operations are required. The unit can be opened and shut down by other staff members on a part-time basis. Hair can save a lot of manpower costs. One boiler is calculated by three operators. The monthly salary is 800 yuan, and the annual salary is 3*12*800=28800 yuan. When the vacuum boiler is used, the salary is increased by 300 yuan, and if it is calculated for 4 months, the annual salary is: 3*4*300=3600 (yuan).
5. Reduce investment costs
Although the price of vacuum boiler is more expensive than that of atmospheric hot water boiler, this is because the vacuum boiler has its own high degree of automation, high technology content and long service life. From the perspective of the whole system, the investment in vacuum boiler is saved. , see the table below:
In addition, the service life of the vacuum boiler is more than 20 years, which is 2-3 times that of the atmospheric hot water boiler. According to twice, the use time of one vacuum boiler is equal to two atmospheric hot water boilers. Also less than the investment in atmospheric boilers.
Sixth, the social benefits of using vacuum boilers
1. Reduce atmospheric pollutant emissions
The vacuum boiler emits pollutants and low pollutants. The environmental protection department tests that the nitrogen oxide content in the flue gas is about 82.3mg/m3, the soot emission is about 0.7mg/m3, and the Ringermann blackness is less than one. The nitrogen oxides specified in the Boiler Air Pollution Emission Standard are less than 300, and the smoke is less than 30, and is much lower. Vacuum boilers should be the first choice for hot water supply equipment as more and more cities begin to carry out blue sky projects.
2. Reduce the accident loss of atmospheric pressure hot water boiler
Because the vacuum boiler works under negative pressure, the internal working pressure is always lower than the external atmospheric pressure. It is not in the scope of pressure vessel management, and there are electrical safety protection measures such as pressure, temperature and liquid level, and mechanical safety protection devices for explosion-proof doors. When the internal pressure tends to the outside atmospheric pressure (which is still negative pressure at this time), it is protected. At the same time, if the internal pressure of the boiler reaches 0.1Mpa (gauge pressure), the explosion-proof door automatically opens the pressure relief. Moreover, the internal hot water is treated in a special process and is in a vacuum environment without oxygen and carbon dioxide, which will not cause corrosion and scaling. Therefore, there is absolutely no danger of explosion, so there is no need for the annual review and approval of the labor department. . It avoids the great human and economic losses caused by explosion accidents in atmospheric hot water boilers.
The lower exhaust gas temperature, the unit is completely insulated after the factory, greatly improving the efficiency of the boiler and reducing the operating cost of the user.
Seven, safe and reliable
The vacuum boiler is always operated under negative pressure, without the danger of expansion and explosion, and has the safety and reliability that cannot be unavoidable by atmospheric pressure and pressure boilers.
Eight, the setting place is diverse
The machine room can choose a variety of places such as the basement, the ground, the middle of the floor and the roof, which greatly saves construction land.
Nine, compact
The Zhongrui vacuum boiler is inserted into the spoiler pipe in the pipe, which increases the heat exchange effect, increases the heat exchange area, makes the structure more compact, and greatly saves space.
Ten, simple operation and maintenance
The heat exchangers and other components of the Zhongrui vacuum boiler are bolted to facilitate inspection, maintenance and maintenance of the equipment.
XI, short start-up time
The preheating time of the Sino-Swiss vacuum boiler is 20 minutes, which greatly reduces the user's operating costs.
12. Unitization
Unit body, heat exchanger, furnace body insulation, protective cover plate integration, saving user investment.
Zhongrui vacuum boiler adopts imported low Nox burner, which has low smoke emission and legal standards, and is an environmentally friendly product, which fully meets the requirements of national first-class regions.
Thirteen, security protection
Zhongrui vacuum boiler is equipped with multiple safety protection devices such as temperature overheat protection, vacuum switch, explosion-proof port, high and low water level protection, and there is no danger of overpressure, dry burning, explosion and rupture.
Fourteen, one machine diversity
A vacuum boiler can meet the needs of users' heating, sanitary hot water and advanced swimming pools. One or three circuits can be set on one machine to meet different needs.
Fifteen, long service life
The use of high-purity hot coal water, the machine will never scale; the machine maintains vacuum and oxygen-free, eliminates the oxygen corrosion of the steel plate inside the unit, and makes the life of the vacuum boiler semi-permanent and has a service life of more than 20 years.
Sixteen, more clean
Zhongrui vacuum boiler uses stainless steel tube heat exchange to make the hot water produced more clean and hygienic.
Seventeen, high degree of automation
Zhongrui vacuum boiler adopts microcomputer automatic control, which reduces the working intensity and is convenient for automatic operation with one touch.
Nineteen, simple system design
Zhongrui vacuum boiler adopts stainless steel heat exchanger, which can directly pass to the user, can reduce heat exchanger and other components, and make the system design simpler.
Twenty, exempt from complicated approval procedures
The unit is operated under vacuum, which simplifies the procedures for approval, annual review, etc. The operation does not require a certificate.
1. Built-in heat exchanger realizes phase change heat transfer. The heat exchanger is a fixed tube plate type, and the two ends are detachable tube boxes. The tube box is a baffle plate. The tube plate is subjected to the forging pressure plate according to the strength calculation. The heat exchanger tube is made of stainless steel SUS304 material. Users can also choose other materials, such as SUS344, copper and so on. The working pressure of the tube is 1.6 MPa, and the shell side is connected to the vacuum chamber.
2. The cleaning (washing) and maintenance of the tube process is very convenient. As long as the tube boxes with threaded ends are opened, it is possible to inspect all the tubes of the heat exchanger, and it has nothing to do with the vacuum chamber of the boiler, and will not damage the boiler. The airtightness does not affect the vacuum degree of the boiler. When the boiler has two heat exchangers, it can be cleaned and inspected while the boiler is running, which is extremely convenient.
3. The number of return cycles of the circulating water of the heat exchanger can be set to two return strokes, four return strokes, six return strokes, and eight return strokes. According to the demand of the outlet water temperature, the general air conditioning water is two return strokes, and the domestic hot water water is four. Return trip.
4, the heat exchanger in the boiler has special requirements, the use of SUS304 stainless steel pipe, φ14 × 1.0 standard boiler heat exchanger special stainless steel pipe, this pipe processing requires special process. The pipe is not easy to scale, has high heat transfer efficiency, does not rust, and is superior to ordinary heat exchange tubes in terms of water quality and flow rate limitation.
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