Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

If the level of energy consumption cannot be significantly reduced, the current resources and environment may not be able to bear it. Therefore, "energy saving and emission reduction" made the strongest voice at the "two sessions"; from the central to the local, from the government to enterprises, energy conservation and emission reduction have been included in the important agenda.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

1 Introduction

　　 In recent years, large-scale smog has continued to occur across the country, causing serious pollution. President Xi personally intervened during the inspection. Severe environmental pollution has questioned our previous economic growth mode and even the economic structure. If energy consumption cannot be significantly reduced, the current resources and environment may not be able to bear it. Therefore, "energy saving and emission reduction" made the strongest voice at the "two sessions"; from the central to the local, from the government to enterprises, energy conservation and emission reduction have been included in the important agenda.

　　 Energy saving and emission reduction is a major event that benefits the country and the people, and it is by no means optional for industry. If the production capacity of industrial enterprises is close to saturation, and the central government focuses on supporting the tertiary industry, then a considerable proportion of enterprises in each traditional industry will fall, and the remaining enterprises must be competing Enterprises with cost advantages. Energy-saving is related to the cost of an enterprise, which in turn affects the break-even point. Quantitative changes cause qualitative changes, which may affect survival. This is especially obvious for certain industries with high energy consumption and low gross profit margins.

　　User companies should take precautions and reduce costs through energy-saving work, increase gross profit margin, and reduce burden. Energy saving is not only one of the direct ways to reduce production costs, but also an important way to enhance the endogenous power and market competitiveness of enterprises.

　　2, compressed air system energy saving plan

　　2.1 Fermentation process improvement and group control

　　 Fermentation process is the core process of pharmaceutical companies. Generally, centrifugal air compressors are used to generate large flow of compressed air and supply air to the fermentation tank to meet the requirements of aerobic fermentation.

With the development and growth of a pharmaceutical company, the number of fermentation tanks has increased from 19 to the current 24. The centrifugal air compressor consumes a large amount of electricity per hour, continues to operate 24 hours a day, and consumes high energy costs, which account for the company’s electricity bill. Nearly 60%. Through continuous improvement, the current fermentation energy consumption has been reduced by about 30%, creating a lot of pure profits for the company.

The main improvement method is to continuously monitor the fermentation process according to different fermentation varieties to meet the best fermentation process requirements, and on this basis to make intelligent adjustments to make the gas supply pressure and gas flow rate meet the best conditions. Improve fermentation efficiency, increase production, and achieve increased production, income, and cost savings for enterprises. This technology focuses on the use of monitoring systems and air compressor group control systems to make process requirements more accurate and gas use more efficient. With the assistance of the monitoring system, the process is continuously improved.

　　2.2 Create a precedent for centrifugal air compressor free speed adjustment

　　2.2.1 Adjustment method of centrifugal air compressor

　　 Centrifugal compressor has the advantages of stable operation, large flow, high design efficiency, etc., but it also has the disadvantages of complicated flow adjustment and prone to surge.

　　 The three commonly used flow adjustment methods for centrifugal compressors are:

　　 (1) Adjust the speed. By adjusting the speed, the characteristic curve of the centrifugal compressor shows a parallel movement, with different flow-pressure characteristics at different speeds, as shown in Figure 1.

　　 It can be seen from the figure that as the speed decreases, the corresponding flow and pressure decrease, and the curves are parallel to each other. This is the "similarity principle". The following characteristics can be achieved by adopting the speed drop to adjust:

　　A. No resistance loss is introduced. By reducing the speed, the impeller's work will naturally decrease, and the flow and output pressure will show a downward trend. The flow can be adjusted without introducing resistance links. Since there is no resistance link, energy will not be lost due to resistance.

　　B. The loss during compression is reduced. By reducing the speed, the relative movement speed of the impeller and the air slows down, and friction and other losses have a downward trend. Reflected in the reduction in heat production during compression, and reduced loss can save power consumption during compression.

　　Adjusting speed is an effective adjustment method for centrifugal compressors. Because it does not cause resistance loss and reduces compression loss, it is the most energy-saving adjustment method. It is widely used in steam turbine compressors and has many applications. Therefore, the energy-saving system should give priority to the way to adjust the speed. However, for a centrifugal compressor driven by a motor, its speed is basically fixed, and it is difficult to adjust the speed in a simple way. The usual frequency conversion speed control can easily cause the compressor to surge. Therefore, you should choose an advanced and mature The corresponding speed adjustment is carried out by the technology, and this plan will be focused on.

　　 (2) Adjust the valve. The regulating valve is a simple way of regulating centrifugal compressors. Through the adjustment of the valve, the opening is reduced, and a pressure difference is formed on both sides of the valve, which reduces the effective output pressure of the system and restricts the gas flow, thereby reducing the flow rate and operating the system at the required balance point.

　　Valves are divided into intake valves and exhaust valves, which have different functions:

　　A. The obstructive effect of the intake valve reduces the actual intake pressure and forms a certain degree of vacuum. The incoming gas becomes relatively thin, causing the flow rate to drop. At the same time, the intake valve will also increase the intake temperature.

　　B. The obstructive effect of the exhaust valve increases the actual output pressure, which makes the compressor move to the operating point where the pressure increases and the flow decreases, and the flow is restricted.

　　 In summary, the function of the valve can be summarized as the introduction of flow resistance to reduce the flow rate to meet the requirements of the process and cause energy loss.

　　The energy loss of the valve is shown in Figure 2.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise 　　 After the gas flows through the valve, because the valve is not fully open, there is resistance, the pressure drops from P1 to P2, forming a pressure difference △P, and the power loss is:

　　W=△PF=(P1-P2)F

　　Due to the energy loss caused by the pressure difference, the overall performance will decrease, and the efficiency and displacement of the compressor will decrease simultaneously.

　　(3) Adjust the guide vanes. Guide vane adjustment is an adjustment method of centrifugal compressors. It induces the gas to flow along the inclined guide vanes to make the gas pre-rotate, thereby reducing the relative speed between the gas and the rotating impeller, reducing the work and reducing the degree of compression. , The flow is reduced. The effect and energy loss of guide vane adjustment are between speed adjustment and butterfly valve adjustment.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

　　 To sum up, the core method of this program is to replace the "regulating valve" with a more superior "regulating speed", and to improve the adjustment method to avoid the energy loss of the valve, while reducing the gas temperature to achieve energy saving. Moreover, lowering the temperature will also help reduce compression power consumption. Therefore, the energy saving effect is superimposed, and the overall energy saving effect is better.

　　2.2.2 Centrifugal air compressor power saving principle

　　 The best adjustment method for centrifugal compressors introduced above is speed adjustment. This solution is developed around speed adjustment. During operation, the process of adjusting the speed of the centrifugal air compressor is to calculate the optimal working state at any time according to the real-time sampling of a series of variables of the gas compressor; this scheme takes into account the gas supply and energy consumption, and realizes Optimal energy saving. It is energy-saving control through the estimation of the optimal working state, similar to a tireless gas compressor expert has been diagnosing the gas compressor in real time. When adjusting, try to be optimal, and minimize repeated adjustments, so that the output of the gas compressor is the most stable state, and the designed maximum efficiency operation is achieved, and the energy saving effect is significant.

　　 For centrifugal gas compressors, the main steps to save energy are:

　　 (1) Avoid gas venting and bypass problems;

　　 (2) The best match of flow and pressure to meet the maximum efficiency point operation;

　　(3) The best control method enables operation under optimal conditions and avoids the possibility of surge.

　　In the actual application, the control method adopted is roughly introduced as follows: Through actual operation, the current flow demand is evaluated, and the actual output speed is measured. According to the difference between the two, calculate the rate of air pressure change, and then estimate the trend of air pressure increase and decrease, and predict the future air pressure change. According to this trend, the air compressor is adjusted gradually and slowly in advance, so as to ensure the stable air pressure and the stable operation of the air compressor.

　　It analyzes the operation of the centrifugal compressor in real time by measuring the operating parameters, and normalizes the parameters into the system standard format. Then, according to the parameters of pipe network pressure and flow, the maximum efficiency estimation system is carried out to estimate the maximum efficiency of the current centrifugal compressor, which can be applied to the operating state with the largest valve opening and the least compression heat. And through the feedforward control, some parameters are observed in advance, and together with the maximum efficiency calculation, a reasonable control command is formed. The purpose of feedforward control is to avoid frequent system fluctuations caused by the response lag of compressed gas. Finally, combined with a special algorithm (invention patent) to prevent surging, a speed command is formed, and the speed control system is commanded from this, so as to achieve reasonable speed adjustment and ensure the continuous and efficient operation of the centrifugal compressor.

　　 2.2.3 Technical advantages

　　 Times Keyi Centrifugal Air Compressor Power Saver is specifically for centrifugal compressors, and has a number of national patents and software copyrights, as listed in Table 1.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

These patented technologies are the technical results obtained by Beijing Times Technology New Energy Technology Co., Ltd. in the energy-saving practices of the past few years after many tests, analysis and improvements. They have very typical and successful application cases and have great promotion value. .

　　In the research and development process, combined with the application of aerospace technology, an expert control system integrating "artificial intelligence" and "big data" is adopted, which reflects the theoretical knowledge and field experience of technical experts. After actual operation, the effect is remarkable.

　　2.2.4 The difference between centrifugal air compressor power saving king and frequency conversion

　　The industry has once recognized that centrifugal compressors cannot use frequency conversion adjustment. This is because frequency conversion adjustment uses feedback control, which continuously adjusts the speed according to changes in air pressure. Due to the constant change of air consumption, the compressor speed constantly changes, and it shows natural oscillation and wide fluctuation. For centrifugal gas compressors, frequent adjustments of frequency conversion can easily reach the surge line and induce the possibility of surge. At the same time, the efficiency of the compressor is low when the rotating speed of the compressor is constantly fluctuating, and the energy saving effect is not ideal.

　　This energy-saving system draws on the function of frequency conversion to adjust the motor speed, and according to the special requirements of the centrifugal air compressor, the frequency conversion technology has been specially improved and upgraded. It is a special equipment, which is different from the general high-voltage frequency conversion. In terms of the control system, the frequency calculation mode is mainly improved. Based on the research of the characteristics of the centrifugal compressor, the innovative patented technology makes the centrifugal compressor far away from the surge line during variable speed and avoids surge. At the same time, the more stable speed also improves the efficiency of the centrifugal compressor.

　　 Figure 4 shows the running screen of the software monitoring system.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

　　Through the development of energy-saving work, the power consumption of the centrifugal compressor, the main engine of the enterprise, has been significantly reduced, and the overall operating efficiency of the enterprise has been improved, which has played a positive role in improving the operating efficiency of the enterprise.

　　2.3 Case of a pharmaceutical company

　　 There are three air compressors in the plant, one for use and two for standby. The basic operating parameters are shown in Table 2.

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

　　 From the data point of view, the three air compressors belong to one use and two backups, and usually only one is in operation. From the perspective of the loading ratio, the loading rate is 57%. When loading, the apparent power is 125kW, and the active power is about 112kW, which is at full load; when unloading, the actual load power still reaches 52.6kW, and the active loss during unloading is estimated to be about At 31.6kW, it can be seen that the loss is relatively large.

　　 The above three air compressors have the following improvements:

　　 (1) The efficiency of air compressor is low, and the compression method needs to be changed to improve efficiency.

　　 (2) There is serious no-load power consumption.

　　 It is necessary to improve the operating conditions of the air compressor, so as to achieve the purpose of sufficient air supply, reduced energy consumption, and disappearance of no-load power consumption.

　　 Energy-saving renovation content (table 3)

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

　　 Construction period: equipment manufacturing: 10 days, installation and commissioning 1 day.

　　 Energy-saving renovation effect:

　　 (1) Power saving (table 4)

Analysis of System Energy Saving Scheme of Centrifugal Compressor Application Enterprise

　　 (2) Reduce the air compressor oil temperature: drop by about 20 degrees.

　　 (3) Reduce the maintenance cost of the air compressor and extend the service life of the air compressor.