Feasibility analysis of replacing direct fired lit

2022-08-18
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Feasibility analysis of replacing direct fired lithium bromide machine with electric central air conditioner Abstract: lithium bromide absorption refrigerator realizes refrigeration by using the absorption and release of water vapor by lithium bromide aqueous solution at different temperatures. This cycle uses external heat sources to realize refrigeration, and the common heat sources are steam, hot water, gas, fuel oil, etc. Among them, people are used to using lithium bromide water heaters whose heat sources are gas and fuel oil, which are called spontaneous combustion machines

key words: lithium bromide water heater lithium bromide absorption chiller

1, the basic principle of lithium bromide absorption chiller and its development trend in China

lithium bromide absorption chiller uses the absorption and release of water vapor by lithium bromide aqueous solution at different temperatures to realize refrigeration. This cycle uses external heat sources to realize refrigeration, and the common heat sources are steam, hot water, gas, fuel oil, etc. Among them, people are used to using lithium bromide water heaters whose heat sources are gas and fuel oil, which are called spontaneous combustion machines

the rapid development of lithium bromide absorption chillers in China began in the late 1980s because of the serious power shortage caused by the Montreal Protocol on ozone depleting substances (ODS) (hereinafter referred to as the protocol) and the rapid economic growth since the reform and opening up. The main content of the so-called "Protocol" is that in view of the aggravation of the destruction of the atmospheric ozone layer by chlorofluorocarbons and other ozone depleting materials used in refrigeration equipment, countries are limited to prohibit the production and use of all kinds of chlorofluorocarbons before 2000, but it also stipulates that developing countries with per capita consumption of less than 0.3 kg are also allowed to delay the production and use of such fluoride products for ten years (China belongs to this scope). This "Protocol" signed by about 130 parties means a major challenge to the traditional electric civil refrigerator with freon as the main refrigerant, and also provides an excellent opportunity for the development and application of various lithium bromide air conditioners. Lithium bromide absorption chiller is unique in the field of central air conditioning because it can use low-grade heat energy, requires small electric power, uses refrigerant as water, and lithium bromide solution does not cause damage to the environment. In order to meet the cooling demand of air conditioning in the period of serious power shortage in China, it has been encouraged by the government and power departments. Since the late 1980s, there have been more than 100 lithium bromide air-conditioning plants in China, and the manufacturing level and output of their products are second only to Japan and in the forefront of the world. According to incomplete statistics, the output of lithium bromide cold and hot water units in China in 1996 was about 4000, of which direct fired units accounted for more than 30%. Direct fired machine is a new model developed on the basis of lithium bromide absorption refrigerator. In addition to the advantages of absorption lithium bromide machine, it also has the following characteristics:

(1) high combustion efficiency

(2) no boiler room, which is conducive to buildings and halls that are not suitable for boiler rooms

(3) both refrigeration and heating, which can be used for domestic hot water, and one machine can be used for multiple purposes

(4) balance urban energy supply, Generally, in summer, electric air conditioners consume a lot of electricity and fuel (gas) consumption is low.

in view of this, although the research of direct fired engines in China started late (successfully developed in 1992), the production technology level has been improved rapidly, and there is a reliable quality assurance. This is undoubtedly a glimmer of light in the dilemma for customers who suffered from complex procedures for power capacity increase, difficult approval, high charges, annual rise in electricity charges and urgent need to configure central air conditioning. Especially for Hunan users, Changsha Yuanda air conditioning company has won a large number of customers with its strong advertising offensive, flexible sales methods and thoughtful and fast service, and has steadily occupied half of the central air conditioning market. This is not only the result of power shortage in the past, but also the inevitable reflection of market competition

however, it is through the in-depth study of the lithium bromide unit that we know that it is, after all, the product of a serious power shortage period. Due to its large waste of one-time energy, low thermal coefficient, high comprehensive energy consumption (the primary energy consumption of the steam type is 2-3 times that of the electric type, and that of the direct combustion type is about 1.6-2.1 times that of the electric type), the inability to carry out refrigeration at a lower temperature below 4 ℃, the rapid decay of the direct combustion machine, the short service life of the whole machine and other fatal weaknesses, Although it saves electricity, it does not save energy, which is only attractive to Asian countries that are generally short of electricity, especially countries rich in crude oil and natural gas resources; In western developed countries, due to the general emphasis on the comprehensive benefits of environmental protection and energy, lithium bromide units have always been unable to form a leading market product. For example, in the U.S. market, where the output of air conditioners ranks first in the world, lithium bromide units account for less than one tenth of the total refrigerator products

2. Economic comparison of electric air conditioners, heat pumps, and electric boilers replacing lithium bromide direct fired engines

(1) current situation: for a long time, the reality of the "seller's market" of power commodities has made the power system tired of coping with the contradiction between power shortage and rapid economic growth, neglected the analysis and research of the power market, and did not foresee the inevitability of transforming power commodities into a "buyer's market", so that it was at a loss when this situation came, Unable to respond in a timely manner to the new relationship between supply and demand. On the contrary, lithium bromide air-conditioning manufacturers have long been confident, making rapid adjustments and formulating more attractive marketing strategies for the market with abundant power supply. We have made great efforts in reducing the price, strengthening services, improving product quality and providing users with detailed economic comparison plans before sales

(2) economic analysis: Table 1 Comparison between electric air conditioning and direct fired lithium bromide air conditioning

electric air conditioning

(ground source heat pump with heat recovery)

direct fired lithium bromide air conditioning

type of energy

Electric

fuel and gas, a small amount of electric heat pump

functions

cooling, heating, hot water supply

cooling, heating, hot water supply

safety

excellent

because the fuel has special fire and explosion-proof requirements, Unsafe

Maintenance

convenient

easy to leak, large loss of lithium bromide, strong corrosion of lithium bromide solution to carbon steel, Inconvenient

service life

years

10 years or so (the cooling capacity attenuation rate of the cooling machine running for more than 3 years is more than 20)

cost comparison

machine investment

machine is cheap (domestic machine can meet the requirements, and the price of imported machine is also lower than that of direct fired machine)

machine is expensive (high import rate of components, high advertising costs and profits)

operation cost

is slightly lower (current electricity price)

machine is slightly expensive (current electricity price).Current oil price)

total investment

large (including capacity increase and power distribution equipment)

small (small power distribution capacity)

environmental protection

no pollution, but the operation of the host has noise

exhaust gas pollution, and the operation of the host has no noise

as shown in Table 1, although the electric air conditioner has many advantages, such as clean energy, safety and health, high refrigeration coefficient, long service life, low price and convenient maintenance

a provincial authority building, with an area of about 50000 square meters. 5. This product can be widely used in aerospace, petrochemical, auto parts, engineering plastics, wires, cables, square meters. It needs to be equipped with cooling, heating and domestic hot water functions. The first phase load is as follows:

cooling load 3million kcal/h, heating load 2.4 million kcal/h, hot water 590000 kcal/h. There are four options available:

a, 2 sets of 1.5 million kcal/h Yuanda direct fired engines

b, 2 sets of 1.5 million kcal/h centrifugal electric coolers and 1 set of 6-ton oil boiler

c, 5 sets of 300000 kcal/h air-cooled cold water (heat pump) units. Table 2 Comparison of initial investment costs unit: 10000 yuan

scheme

a

b

C

P> 1, host purchase cost

382.2

230

298

2, host power capacity increase fee

2.65

89.8

83.25

3, terminal power capacity increase fee

.

3.6

4, boiler power capacity increase fee

5, boiler purchase and installation fee

72.6

6, power distribution equipment fee

1.8

56.7

40.5

7 Cold coal purchase fee

30

8, total

420.25

449.1 (of which 89.8 power capacity increase fee can be reduced, actually 359.3)

421.75 (of which 83.25 power capacity increase fee can be reduced, actually 338.5)

for the above three schemes, except C, the other two schemes need to be equipped with cooling water system. Due to the large heat emission of lithium bromide unit, the capacity of its cooling water tower and cooling water system is correspondingly large (usually 30 ~ 40% higher than that of electric refrigeration unit), and the initial investment cost is even higher. In addition, compared with the electric refrigeration unit, the bromine machine covers a large area, the machine room height is high, and the equipment weight is large. Due to the special explosion-proof and fire-proof requirements of the fuel, its design complexity is high, and it also needs to build special oil depots and other supporting facilities. In addition, the lithium bromide machine has high requirements for air tightness. If the vacuum degree of the unit is damaged, its performance will be greatly affected, so the requirements for operators are high. Therefore, on the whole, scheme D is more economical in terms of initial investment and annual operation cost. Especially in our southern region, the long operation time of water chillers is more beneficial to air-cooled units, and the initial investment payback period is shorter. However, considering the energy efficiency ratio, the social benefit of using ground source heat pump with heat recovery technology is higher. Table 3 Comparison of annual operating costs (calculated according to the same maintenance and other costs) unit: 10000 yuan/year

scheme

A (fuel + electricity)

b (electricity + fuel)

C (electricity)

cooling

(1), 0.503 yuan/kwh

110.67+2.84

91.36

84.5

(2), 0.712 6 yuan/kwh

110.67+4.04

130.05

120.29

heating

(1) 0.503 yuan/kwh

83+2.13

83+2.13

63.38

(2), 0.716 yuan/kwh

83+3.03

83+3 marks the authority and credibility of the test report issued by Jinmin laboratory 03

90.22

total

(1) electricity price

198.63

176.13

147.88

(2) electricity price

200.74

216.08

210.51

(3) cost analysis: compared with the initial investment of the other two schemes, scheme a has the largest capital demand and the smallest power consumption. The initial investment of scheme B is 85.5% of scheme a, and the operation cost of scheme B in category (1) electricity price is 88.7% of scheme a; In category (2) electricity price, the operation cost of scheme B is 107.6% of that of scheme a

3. Conclusion:

(1) because the lithium bromide unit achieves the purpose of air conditioning at the cost of consuming heat energy, its power consumption is very small (only about 2% of the electric type), but its heat consumption per unit refrigerating capacity is large, that is, its refrigeration coefficient is small, and the current maximum value in China is only about 1.2, while the electric type unit is more than 3.5. Therefore, the lithium bromide unit only uses less electricity and cannot save energy. Therefore, the best use condition of this model is the place with waste heat and waste heat or the area without electricity (hot water type, steam type rather than direct combustion type), and it can never replace electric refrigeration

(2) China's energy is mainly coal and hydraulic resources, while oil resources are in short supply and output is insufficient. This energy composition is suitable for the development of electric power industry. The selection of tension machine fixtures should also be based on non standardized configuration or related expansion of configuration industry. Therefore, the development of air conditioners should be based on electric type, and fuel oil The development of direct fired lithium bromide absorption units with gas as the fuel for the development of strategic emerging industries is not desirable in China

(3) for example, the annual operating cost of electric central air conditioning with ground source heat pump and heat recovery technology is lower than that of lithium bromide direct fired units, especially in terms of service life and maintenance management

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