Liu Xiaodong, Su Baocheng, He Tao
(Ningxia Baofeng Energy Group Co., LTD., Yinchuan, Ningxia 750001)
[Abstract] : Aiming at the problem that the design flow rate of the compressor unit significantly exceeds the production operation demand, resulting in energy waste, a solution based on the inventive Problem Solving Theory (abbreviated as TRIZ) is proposed. Through the functional model analysis and causal chain analysis of the compressor unit system, the fundamental cause of energy waste in the compressor unit was determined. By using tools such as physical contradictions, object-field analysis and technical contradictions, a design scheme for achieving automatic control through optimizing the anti-surge line of the compressor was proposed. After application verification, this scheme has reduced the opening degree of the anti-surge valve from 38% to 17%, saving 14.8% of energy. It provides a reference and technical support for optimizing compressors in similar devices.
[Key words] : TRIZ Theory Compressor; Surge Functional model Analysis of causal chain
Chinese Library Classification Number: TH45 Document Code: B
Article Number: 1006-2971 (2026) 01-0051-06
Introduction
The Invention Problem Solving Theory (abbreviated as TRIZ), developed by G.S. Altshuller of the former Soviet Union based on the analysis and research of 2.5 million patents from various countries around the world, summarizes the laws followed by various technological evolutions and establishes a methodological system that can effectively describe the development of new technologies. G.s. Altshuller believed that the fundamental principles of invention problems are objectively existent. These principles were organized into the TRIZ theory, and those who master this theory make invention problems predictable [1]. The TRIZ theory is also regarded as a toolkit for a series of analytical methods and solutions [2].
The TRIZ theoretical system includes methods such as the Nine-screen method, the final ideal solution, the little man method, the STC operator, and the goldfish method, which are used to assist innovation. Functional analysis, causal chain analysis, contradiction analysis, object-field analysis and ARIZ algorithm for problem analysis; 40 inventive principles, separation principles, 76 standard solutions, knowledge effect libraries and tailoring for problem-solving [3].
The application of TRIZ in the manufacturing field is mainly reflected in aspects such as improving production efficiency, enhancing product quality, optimizing process technology, and avoiding patents [4].
In the field of energy conservation, CHIU et al. [5] successfully developed an environmentally friendly paint for roof energy conservation based on TRIZ technology. The results of heat resistance tests indicated that the new material could save more than 20% of electricity. Liu Xiancheng et al. [6] applied the TRIZ method to the energy-saving transformation of reciprocating compressors. By adding a gas valve regulation system and changing the crankshaft amplitude, the purpose of regulating the compressor power was achieved. Qi Haiyuan [7] organically combined TRIZ with the theory of building energy-saving construction systems, constructed an evaluation and innovation model for building energy-saving technologies, and verified the effectiveness of the method through wall design. Zhao Cunyou et al. [8] utilized the ARIZ algorithm in the TRIZ theory to analyze the reasons for the high energy consumption of the cutting drum in the coal mining machine and formed an effective energy-saving scheme through the exploration of derived resources. Jin Lin et al. [9] improved the design of the heat exchanger for the printing machine by means of the TRIZ theory, and selected finned tubes with appropriate ribbing coefficient and emissivity, which enhanced the heat generation efficiency of the heat exchanger. Alvarez et al. [10] proposed an ecological innovation model for renewable energy based on Exergy analysis, TRIZ theory and knowledge management.
During the operation of a centrifugal compressor, when the flow rate drops to a certain extent, flow instability will occur, that is, surge. Surge is an inherent characteristic of centrifugal compressors, which can cause huge impacts and severe vibrations inside the compressor. In severe cases, it can lead to equipment damage and pose a threat to personnel safety [11]. Therefore, in the operation control of compressor units, it is extremely important to prevent surge. The performance curve of the compressor is tested under certain intake conditions and gas components. The energy consumption value of the compressor is generally calculated through the performance curve. Research shows that the error of calculating the operating parameters from the theoretical performance curve can be as high as 20%, and the compressor operation plan formulated based on this will lose its energy-saving property [12]. The highest points of the connection performance curve at different rotational speeds form a limit curve characterizing the surge of the compressor. If the operating point of the compressor is on the left side of the curve, the surge phenomenon will occur [13]. When the operating conditions change, the performance curve will shift, and the shift is highly uncertain. Therefore, certain methods must be adopted to obtain the actual performance curve [14]. Xu Ye et al. [15] proposed a method for diagnosing compressor surge based on multi-source information such as flow, pressure and vibration; ALSUWIAN et al. [16] reviewed the anti-surge control system of compressors and advanced fault-tolerant control technologies; Zhang Pingdeng [17] optimized the LSSVM model to predict the performance curve of centrifugal compressors by improving the particle swarm IPSO algorithm; Chen Liqiong et al. [18] proposed an adaptive performance curve generation method based on ANFIS, with an error of less than 3% compared to the actual operation curve.
Systematic analysis
2.1 Functional Model Analysis
The functional model describes the functions of engineering systems and hypersystem components, as well as useful functions, defective functions, performance levels and costs. This model only expresses the interaction relationship of system components and is independent of the sequence of functional implementation. For defects caused by the interaction between components, based on this model, the causes of the problems and the conflict areas related to the problems can be determined [19]. This paper first establishes a functional model to determine the conflict area, and then establishes a causal chain to determine the conflict. The compressor unit system is defined as an engineering system, with system components including motors, speed increasers, compressors, outlet regulating valves, inlet regulating valves, anti-surge valves, CCS systems, etc. The components of the super system are electrical energy, air, operators and catalyst activity. Analyze the functional relationships among the components of the engineering system and create a functional model, as shown in Figure 1.
Through the analysis of the functional model diagram, it can be found that the functional defects of the engineering system are excessive supply of air volume to the regenerator by the compressor, insufficient collection of catalyst activity by the CCS system, and harmful control of the inlet and outlet regulating valves and anti-surge valves by the operators.
2.2 Causal Chain Analysis
As a key tool for problem analysis in the TRIZ theoretical system, causal chain analysis identifies and analyzes the key causes of engineering systems, finds the potential and deep-seated reasons in engineering systems, links the target problem with various underlying shortcomings, and then finds the breakthrough point to solve the problem [20].
Due to the replacement of high-efficiency catalysts in the reaction section, the demand for regeneration air has decreased compared to the original design, and a large amount of air is released through the anti-surge valve. In response to the problems arising from this research, the high energy consumption of the compressor unit was defined as the initial issue. The compressor system was analyzed using the causal chain, and the analysis results were obtained, as shown in Figure 2.
The analysis results initially identified three key technical issues that may lead to high energy consumption of the compressor unit: local venting of excess air, large opening of the anti-surge valve, and limited application of automation technology.
Problem-solving applying the TRIZ theory
Based on the functional defects and key issues obtained from the functional model analysis and causal chain analysis, improvement plans for the compressor unit system are proposed respectively by applying the nine-screen analysis method, life curve, material field analysis, physical contradiction, final ideal solution, technical contradiction, resource analysis and STC operator. Due to space limitations, this article only provides a detailed description of the application of some methods.
3.1 Solutions Based on physical contradictions
According to G.S.Altshuller's definition of physical contradiction, a physical contradiction occurs when the engineering parameters of a technical system have opposite requirements.
Describe the key issues that conform to physical contradictions in accordance with the norms, separate the two sides of the contradiction based on the core idea of resolving the contradiction, and formulate specific solutions by referring to the corresponding innovation principles [21]. The idea of separating physical contradictions is shown in Figure 3.
To achieve the goal of reducing the energy consumption of the compressor unit, the opening degree of the anti-surge valve is defined as a physical contradiction. To ensure that the compressor does not experience surging, the anti-surge valve needs to be opened wider, while to reduce the energy consumption of the compressor, the anti-surge valve needs to be closed narrower. According to the expression norms of physical contradictions, it can be described as: In order to prevent surging, the anti-surge valve of the compressor system needs to be opened wide.
To reduce energy waste, the anti-surge valve of the compressor system needs to be closed slightly. To achieve the ideal state of the technical system, the contradictory demands of this parameter can be realized under different conditions of the anti-surge valve. By adding guiding keywords that describe the conditional state, the physical contradiction is further described as: when the operating state of the compressor approaches the surge line, in order to prevent the surge phenomenon, the anti-surge valve needs to be opened wide.
When the compressor's operating state is far from the surge line, in order to reduce energy waste, the anti-surge valve needs to be closed slightly.
At this point, the contradiction is separated based on the separation of conditions. The innovative principles involved in the conditional separation method include segmentation method, combination method, nesting method, reverse method, curve method, feedback method, substitution method, performance transformation method, etc.
For the issue of reducing the energy consumption of compressor units, an innovative principle, the "segmentation method", is adopted to formulate a solution. The specific solution is:
Draw a line to the right of the surge line as a buffer. When the operating state of the compressor approaches this line, open the anti-surge valve wide to ensure that the compressor does not experience surge. When the compressor is operating far from this line, close the anti-surge valve to reduce energy waste. This method resolves the physical contradiction that the anti-surge valve needs to be both opened wide and closed slightly.
3.2 Solutions Based on Object-field analysis
Matter-field model analysis is an important problem description and analysis tool in TRIZ theory, which can visually represent system problems. In the process of problem-solving, the standard solution can be found by using the search method to improve or solve the problem [22]. The general process for solving problems using object-field analysis is shown in Figure 4. G.s. Altshuller believed that all functions could be decomposed into two substances
And a field, that is, a function is composed of two substances and three elements of a field, namely the object of action, the tool and the field. BELSKI [23] proposed a standardized process for analyzing and solving technical problems based on the object-field model. After establishing the solution model, specific solutions are obtained based on the forms of interaction between substances [24].
The object-field model of the key defect is established based on the functional model, as shown in Figure 5. The two substances in the system are the compressor unit and the regenerator. The interaction between the two is an electric field. The dotted line indicates that the compressor unit has a harmful effect on the regeneration air supply of the regenerator.
For non-effective complete models, corresponding to the standard solution of Class 1.2 in TRIZ theory, "disassembling the object-field model", there are five general solutions to the problem model: (1) "Introducing S3 to eliminate non-effective effects";; (2) "Introduce improved S1 or S2 to eliminate non-effective effects." (3) "Introduce substances to eliminate non-effective effects"; (4) "Use F2 to counteract the ineffective effect." (5) "Eliminate the influence of the magnetic field." Here, in order to reduce the excessive function of the compressor unit on the regenerator's regeneration, we choose the standard solution of the second type to formulate a plan. The specific plan is:
A solution based on ";introducing improved S1 or S2 to eliminate ineffective effects". The existing compressor unit is driven by a fixed-frequency motor, and the air volume cannot be adjusted through the input side. We have improved the drive motor of the compressor unit and transformed it into a variable-frequency regulation system to achieve adjustable air volume, as shown in Figure 6.
3.3 Solutions Based on technical contradictions
Technical contradiction refers to the situation where, in order to achieve the current technical system's goals, the parameters corresponding to two different functions of the system are mutually exclusive, that is, when one parameter is improved, the other is deteriorated [25]. The steps to solve technical contradictions using the TRIZ theory are: clarify the problem and identify the contradiction points of the problem; Transform the problem into the expression form of technical contradiction norms; Apply the contradiction matrix to find the corresponding invention principle; Inspired by the principle of invention, a solution was proposed [26]. The process of solving problems based on technical contradictions is shown in Figure 7.
Based on the results of the causal chain analysis, problem one is identified: the opening degree of the anti-surge valve is large. Description of technical issues. If the anti-surge valve is blindly closed to reduce the energy loss of the compressor unit, it may cause the compressor to surge.
Define technical contradictions. Parameter to be improved: No.22 Energy loss; Deteriorated parameter: No.27 Reliability.
Search for the contradiction matrix and obtain the corresponding invention principle: No.11 Prevention in advance.
Inspired by the principle of this invention, a solution was obtained: draw the actual anti-surge line of the compressor and perform pressure line control.
Based on the results of the causal chain analysis again, the second question is identified: the application of automation technology is limited.
Description of technical issues. If the anti-surge control of this compressor unit is changed to automatic regulation, it will enhance the degree of automation of the compressor unit, reduce the labor intensity of employees at the same time, but it will increase the complexity of the system and raise the possibility of faults in the instrument control system.
Define technical contradictions. Parameters to be improved: No.38 Degree of automation;
Deteriorated parameter: Complexity of Device No.36.
Search for the contradiction matrix and obtain the corresponding invention principle: No.24 The principle of using mediators.
Inspired by the principle of this invention, a solution is obtained: adding an anti-surge algorithm module and a control operation module to the compressor surge control operation mode. When the surge control operation mode is in the automatic state and the control operation module is in use, the anti-surge algorithm module in the surge control operation mode is associated with the anti-surge valve control operation module at this time. Ultimately, it can achieve automatic monitoring of the surge trend of the compressor unit. If a surge occurs, the system will automatically open the anti-surge valve of the compressor to ensure that no surge will occur.
3.4 Scheme Summary
By applying the functional analysis and causal analysis of the TRIZ theory, and using 10 innovative methods and tools such as the Nine-screen analysis method, life curve, resource analysis, final ideal solution, technical contradiction, physical contradiction, STC operator, and object field analysis, 23 conceptual schemes were obtained. Table 1 presents the summary of the schemes.
An evaluation model was established, as shown in Table 2. 23 innovative schemes were sorted out and evaluated, as shown in Table 3. The top three schemes with the highest comprehensive scores, 11, 21 and 22, obtained the design scheme of achieving automatic control by optimizing the anti-surge line of the compressor.
Application verification
4.1 Implementation of the Plan
First, test the actual surge line of the compressor
(1) Confirmation of the operating status of the unit: The mechanical operation of the unit is normal, the measuring instruments related to the surge test are working properly, and the main process parameters of the unit operation are normal.
(2) After the preparatory work is completed and the test preparation instruction is obtained, the anti-surge control mode is set to semi-automatic, the unit operation status is switched to automatic operation mode, and the opening degree of the inlet valve is adjusted to the test value.
(3) Use the move surge wire button to move the surge wire to the left so that the anti-surge wire is within 1% of the working point, and then start the test.
(4) Upon receiving the command to start the test, gradually close the anti-surge valve. When the flow rate decreases and the working point approaches the surge control line, use the move surge line button to move the surge line to the left and continue to close the anti-surge valve. When the test end condition is met, end the experiment at this point.
(5) Adjust the opening degree of the inlet valve of the unit and proceed to the next step as in steps (3), (4), and (5) until all experiments are completed.
(6) The actual surge line and the optimized anti-surge line were obtained, as shown in Figure 8.
4.2 Effect Verification
When the device load of the compressor is 100%, the opening degree of the anti-surge valve is 17%, which is 21% lower than that before optimization. After control with the optimized anti-surge line, the energy-saving rate reached 14.8%, the optimization effect was better than expected, and the performance acceptance was qualified.
After the project is completed, the annual electricity consumption will be saved by 2,880,914 kW·h. Calculated at an electricity cost of 0.54 yuan per kW·h, the annual cost savings will amount to 1.556 million yuan.
Conclusion
This paper analyzes and studies the phenomenon that the design flow rate of the compressor unit significantly exceeds the actual demand of production operation and the resource allocation is unbalanced. The main contents completed are as follows:
By applying the functional model analysis and causal chain analysis in the TRIZ theory, the problems existing in the air supply system from the compressor to the regenerator were identified: local venting of excess air, large opening of the anti-surge valve, and insufficient application of automation technology.
(2) Based on the innovative methods and tools such as physical contradictions, field analysis, and technical contradictions in the TRIZ theory, and referring to the inventive principles and standard solutions, a design scheme for achieving automatic control by optimizing the anti-surge line of the compressor was proposed.
(3) The implementation effect shows that by referring to the optimized anti-surge line control, the anti-surge valve can be slightly closed under the premise of ensuring the safety of the compressor unit, achieving automatic control and reducing the labor intensity of the operators and the risk of misoperation. The energy consumption data after operation also indicates that this scheme can effectively reduce the energy consumption level of this unit, providing reference and technical support for optimizing compressors in similar devices.
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Author's Profile: Liu Xiaodong (1986-), male, senior engineer, master's degree, mainly engaged in equipment fault diagnosis and technological upgrading.
