Intelligent pump energy saving full cost of life intelligence and economic benefits

First, the pump energy saving potential

According to the information, the power consumption of the pump accounts for about 20% of the total electricity consumption in the country. The motor power of the pump is about 45% of the total capacity of the motor in the country. In the oil and chemical plants, the pump power consumption is even higher, respectively 59% and 26%. Therefore, the energy saving pump is a far-reaching event.

In our country, the energy loss of pump operation system in the past is very big. The adjustment of centrifugal pump adopts the methods of valve control and opening and closing bypass. According to an overseas survey, the average efficiency of 1690 pumps operating in 20 factories is only 40%, with 10% of pump efficiency being even 10%.

The above figures show how huge potential for saving energy is in the pump industry. If all the pumps in service in the country can operate at a 1% efficiency improvement, the annual energy saving will be 4.4 billion kW · h, equivalent to 3.8 billion yuan of electricity (calculated at 0.865 yuan / kW · h for the peak industrial electricity in Shanghai).

Pump efficiency improvements include two aspects: First, improve the design efficiency of the pump host. As the designer in the product design, has done everything possible to improve the efficiency of the host at the design point, so to improve the efficiency of 1% is very difficult. The second is to improve the efficiency of the entire pump operation system. According to some information, the original bypass adjustment into variable speed regulation, the efficiency of the entire pump system can be increased by 30% or more. Therefore, smart pumps mean not the smart pump itself, but the entire pump system (Intelligent Pumping Systems). The emergence of intelligent pump, centrifugal pump into the modern mode of regulation, but also brought a new concept of management, it can be said that the pump system engineering and management of a revolution, but also the inevitable trend of the development of the pump.

Centrifugal pump flow and speed of the first-order proportional to the lift proportional to the square of the speed, power and speed is proportional to the cube, so if the centrifugal pump bypass adjustment to speed adjustment, the effect will be very obvious. If the flow rate is reduced by 10% ~ 20%, the pump parameters are generally shown in Table 1 (without considering the influence of the performance curve). In fact, centrifugal pumps are affected by the performance curve. When the flow rate decreases, the lift will increase, so the lift required for the process can still be maintained, while the energy saving effect will be slightly lower than that in Table 1. The energy-saving effect of other adjustment methods is in between the two.

Table 1 centrifugal pump frequency adjustment and bypass adjustment comparison

Second, the entire life cost

LCC (Life Cycle Costs), also translated as "life cycle costs", refers to the cost of the entire process from product planning until the product is discarded. It includes both the producer's perspective and the consumer's perspective. However, consumers buy products from the hands of producers, therefore, product costs plus product profits, coupled with the cost of consumption, has become the user's full life cost.

According to the author of "The Lifetime Costs of Pumps" [1], the life-cycle cost of a pump includes the initial installation cost, running cost (ie electricity cost), maintenance fee and other expenses. For a typical medium-sized pump plant, the share of its four-part costs is shown in Figure 1.

Figure 1 pump full life cost of four basic costs

Figure 1 cost ratio (wages, price factors, etc.) is made with reference to foreign standards. The initial cost of equipment in the picture only accounts for 10% of the total cost. In fact, the purchase price may vary from manufacturer to manufacturer by 30%, but for a pump with a service life of over 15 years, the initial charge for equipment is often the least considered factor in its full life cost. Maintenance fees often have different views, in Figure 1, the maintenance fee refers to the spare parts costs plus labor costs, which usually account for 25% to 40% of the cost of life , therefore, it will pump the economy than the purchase of the pump The initial cost is more important. The cost of energy can be tested, it can also be calculated according to the performance curve, it accounted for the largest proportion of 45% in Figure 1, in some statistics even up to 70%.

Table 2 life-cycle cost savings actual case summary table

Table 2 is based on the actual number of pumps in Europe, energy-saving renovation of the actual statistics produced, as can be seen from Table 2, pump system, energy-saving focus on operating costs (electricity) and maintenance costs, the initial investment or reconstruction costs generally one year More can be recycled, the longest can be recycled for about three years.

Third, the pump of intelligent

The pump should be intelligent two efforts, one is to hope that the pump efficiency curve is relatively flat, when the flow changes, the changes in efficiency as little as possible. However, the potential in this area is very limited, so the focus is on operational aspects. When the external process flow changes, the pump intelligent system should be able to receive timely changes in process parameters of information, rapid automated operation and the results of the operation feedback to the control valve or inverter, accurately adjust the desired valve opening or Motor speed, change the state to complete response. In all the adjustment methods, especially the most variable speed regulation.

Therefore, the pump intelligent system should include the following main suite: pump host, inverter motor, inverter, signal sensors, control modules, programmable logic controller.

Inverter VFD (Variable Frequency Drives), also known as frequency converter, is controlled by intelligent operation feedback information and inverts the AC input frequency of 50Hz to the current output of corresponding Hertz (Hz). Three-phase motor frequency range of 0-60Hz, single-phase motor frequency range of 40 ~ 70Hz.

Variable speed motor speed n = 60 f (1- s ) / P

Where f - frequency after the exchange of AC frequency, usually 40 ~ 50Hz.

If the slip s = 0.007, the number of motor pole pairs P = 1, then 80% ~ 90% of the flow rate adjustment f = 45Hz and 40Hz (see Table 1).

PLC programmable logic controller, also known as programmable logic controller, is a digital computing operation of the electronic system. It uses a programmable memory, the implementation of internal logic operations, is a computer-based automatic control device to replace the relay, a variety of machinery or manufacturing process control. Intelligent pump programmable controller can control the pump system operation, maintenance management, prevent cavitation, diagnostic alarm. PumpTmart intelligent controller (see Figure 2) of ITT High Quality Pump Company is a more advanced integrated controller that has integrated the control module, programmer, etc., and set the parameters, generally do not need to user-programmed .

Typical intelligent pump system and monitoring principle shown in Figure 2, Figure 3. The corresponding code meaning: C-console, CM-control module, D-motor, P-pump host, PLC-programmable controller, T-signal sensor, VFD-inverter.

Intelligent pump system operation is as follows:

The signal is sent to the control module CM by the inlet / outlet signal sensor T installed at the inlet (or outlet) when the parameters of the outside world (process flow) change (for example, when the outlet pressure drops due to excessive flow). The control module consists of a number of integrated circuit modules, such as the power supply system module CM1, the data acquisition module CM2, the drive control module CM3, the information display module CM4, the input / output module CM5 and the like. The control module displays the result on the signal cabinet C (or control cabinet) and at the same time sends a frequency modulation instruction to the VFD of the frequency converter. After the variable speed motor D receives the FM instruction, it starts to decelerate and the output flow of the pump (host) P gradually decreases. The system Reach a new balance Also connected to the control module is a programmable logic controller that pre-stores pump performance curves, fluid density, control parameters, and more. Under normal circumstances, the pre-stored parameters without any adjustment, when there are major parameters change, you can re-pre-stored parameters. Pump performance curve parabolic shape, the general use of its decline, it is in the pump design or test obtained, you can use a simple mathematical model of its sub-programming.

Fourth, a long way to go

The development and utilization of energy-saving pumps are the result of the joint efforts of the entire pump industry, so there is such a major breakthrough in smart pumps. In this regard, many domestic and foreign companies have done a great deal of work. For example, ITT High-quality Pump Company earlier introduced and exhibited the intelligent pump series in China, put forward the concept of full-life cost and greatly improved the operation of the pump system s efficiency. Shijiazhuang Yi Austrian Technology Development Co., Ltd. took the lead in developing a "pump frequency control energy-saving power calculation and system design" to solve the problem of quantitative calculation of power-saving. There are many individuals also contributed to the development of energy-saving pumps, such as Dalian Li Donggui, invented the "industrial process intelligent pump" patents (domestic patent No. ZL01211714.5, International Publication No. WO02 / 66835AI).

The rapid development of smart pump also depends on the development of inverter technology, so it can be said that smart pump is an example of industrial control automation successfully applied in the pump industry. Now, there are many articles in different areas of technology on the pump and inverter control in industrial applications, the use of intelligent pump is involving a number of industries in the user application of a systems engineering. This systematic project considers not only technology, but more practical and important economic and social benefits. At present, intelligent pump technical problems should not be said that "bottleneck", not long ago held in Shanghai PSC2005 Sixth China International Fluid Machinery, General Equipment Exhibition, ITT high-quality pump company exhibited on the smart pump demonstration system to the audience Fully demonstrated ITT intelligent pump advanced and reliability. What makes the user really have to consider is the ratio of input to output. That is, the increased investment due to the smart pump can take several years to recover. The author believes that the new device, the more scientific consideration is to accept the LCC life-cycle cost of thinking, the transformation of the old device, the payback period is less than 2-3 years is appropriate.

Another issue that needs major consideration is social benefits, which is actually the country's energy policy issue. According to reports, China's GDP accounted for 3.8% of the world in 2003, but the global energy consumption accounted for 11%. China's energy consumption per unit of GDP is 4.3 times that of the United States, 7.7 times that of Germany and France, and 11.5 times that of Japan. China's energy experts call for "China's economic operation is still a high-input, high-consumption and extensive mode of economic growth, which has brought resources exhausted, environmental pollution and many other issues that have been unsustainable." Therefore, digging the energy saving potential and promoting the application of energy-saving system (smart pump) in the huge energy management space of the pump industry is not only the economic benefit of the enterprise, but also a national responsibility to the country

Serial number

Adjustment method

Frequency adjustment

Bypass adjustment

1

Flow regulation

100%

90%

80%

80% ~ 100%

2

Motor speed n / (r / min)

2950

2655

2360

2950

3

Frequency inverter f / Hz

50

45

40

50

4

Head change H (%)

100

81

64

100

5

Power consumption change (%)

100

73

48

100

Serial number

Industrial department / application case

Save the way

saving

cost

Investment recovery

Period (years)

Full life cost

Saving euro

1

Construction / Air Conditioning

Single bypass adjustment of large pumps

Single throttle control large pump

3 sets of variable speed control pump

Electricity fee

47,800

70,400

2

Paper industry / circulating pump

Install 2 different conditions

Circulating pump

Electricity fee

0.5

711,900

3

Chemical / condensate outlet pump

Corrected impeller

Small new motor

Electricity plus

Maintenance fee

0.06

3.1

107,000

8,600

4

Water supply / water distribution pump

For a normal efficiency of the pump

Electricity fee

0.7

121,000

5

Wastewater / sewage pump

Because of the load, there are 3 sets of large pump into a small one

Electricity plus maintenance fee

3.3

38,100

6

Steel mills / water cycle

Take measures to improve the efficiency of the impeller surface

Electricity fee

0.4

25,800

7

Chemical / process export pump

Remove auxiliary cooling

Electricity and water fees

0.2

85,700

8

Household appliances / natural water pump

Variable frequency drive

Electricity fee

0.5

128,000

9

Mine / pump motor

High efficiency motor

Electricity fee

1.8

22,500

10

Power plant / cooling water circulation pump

Change the pump outlet hydraulic characteristics

1 unchanged original volute pump

2 adjustable vane pump

3 adjustable import guide vane mixed flow pump

Electricity fee

1.4

0.4

-

18,394,000

14,518,000

11

Construction / home circulation pump

Change the pump

Electricity fee

930

12

Construction / office circulating pump

Transformation

Electricity fee

10,700

13

Chemical / slurry hose pump

High investment to increase the hose

Maintenance fee

0.8

7930

14

Food industry / diaphragm pump

Add metal valve

Maintenance fee

1.6

3400

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