A power-based air compressor flow measurement method and measurement device

Abstract

The application discloses a kind of power-based air compressor flow measurement method and measuring device, the power-based flow calculation formula of the present application replaces measuring device to obtain air compressor operating flow, improves the measurement accuracy, effectively reduces the measurement cost, avoids the problems such as high installation and use condition requirement, large measurement error and additional pressure loss when using differential pressure flow measuring device;And can efficiently and quickly obtain air compressor operating flow, when operating condition changes, still can obtain flow result at any time, eliminates the debugging adaptation process of flow measurement device, and the measurement result is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air compressor, in particular to an air compressor flow measurement method and device based on power. BACKGROUND

[0002] The operating flow of an air compressor is a necessary measurement in performance test, and currently a differential pressure type measurement device is often used to measure the flow of the air compressor. The differential pressure type measurement device is mainly composed of a throttling element such as an orifice plate, a nozzle or a Venturi tube, and a pressure taking device. When the fluid to be measured fills the pipeline and the measurement device, the flow rate is increased and the static pressure is reduced at the throttling element, thereby forming a differential pressure before and after the throttling element. The differential pressure is measured by the pressure taking device, and the volumetric flow of the measured pipeline is calculated by the formula of the relationship between the volumetric flow and the differential pressure. The differential pressure type flow measurement device has high requirements for installation and use conditions, and the measurement accuracy is generally low. The installation space is insufficient, the installation position is unreasonable, the straight pipe section before and after the measured pipeline is not long enough, the flow distribution in the pipeline is uneven, the inner wall of the pipeline is rough and dusty, and other factors may cause large measurement error. In addition, the measurement device is connected with the pipeline by flanges and other structures, and leakage problems may occur during long-term use, which increases the maintenance workload. SUMMARY

[0003] Technical purpose: in view of the deficiencies of the existing air compressor flow measurement using differential pressure type, high installation requirement and low measurement accuracy, the present application discloses an air compressor flow measurement method and device based on power, which does not need to use a special differential pressure flow measurement device, and directly calculates the flow by the working condition of the air compressor.

[0004] Technical scheme: in order to achieve the above technical purpose, the present application adopts the following technical scheme:

[0005] An air compressor flow measurement method based on power, comprising the steps of:

[0006] S01, respectively measuring the inlet gas temperature and outlet gas temperature during the operation of the air compressor; and calculating the actual total power P of the air compressor s ;

[0007] S02, calculating the work w done by the air compressor on unit mass of air according to the inlet gas temperature and outlet gas temperature of the air compressor obtained in step S01, and obtaining the mass flow of the air compressor

[0008] S03, calculating the volumetric flow Q of the air compressor from the mass flow of the air compressor in step S02 v = Q m *60 / ρ; wherein ρ is the density of the inlet gas, kg / m 3 .

[0009] Preferably, the application calculates the total power of the air compressor in step S01, including: first, determining the power correction coefficient k1 considering the motor and frequency converter loss, the power correction coefficient k2 considering the air compressor system loss, then measuring the total power P of the air compressor input by the power instrument, P s =k1P*1000+k2.

[0010] Preferably, the application determines the power correction coefficient k1 considering the motor and frequency converter loss, and the power correction coefficient k2 considering the air compressor system loss, including: selecting test points under the operating conditions of the air compressor, measuring the input power P t1 and P t2 of the two test points, and calculating the actual total power P z1 and P z2 of the air compressor by detecting the outlet flow pressure of the air compressor, P z1 =k1P t1 *1000+k2, P z2 =k1P t2 *1000+k2; the values of k1 and k2 are obtained by simultaneous equations.

[0011] Preferably, the application calculates the work done by each air compressor on unit mass of air in the N-stage series air compressor system, and substitutes it into the mass flow formula for calculation.

[0012] Preferably, the application calculates the work done by each air compressor on unit mass of air in the N-stage series air compressor system, and substitutes it into the mass flow formula for calculation.

[0013] The application also provides an air compressor flow measuring device, which uses the above-mentioned power-based air compressor flow measuring method for measurement, including a power instrument for measuring the input power of the air compressor, a temperature sensing element for measuring the inlet temperature and outlet temperature of the compressor, and a processor for receiving, storing and processing measurement data.

[0014] Beneficial effects: the power-based air compressor flow measuring method and measuring device provided by the application have the following beneficial effects:

[0015] 1、The power-based flow calculation formula of the application replaces the measuring device to obtain the operating flow of the air compressor, improves the measurement accuracy, effectively reduces the measurement cost, and avoids the problems of high installation and use condition requirements, large measurement error and additional pressure loss when using the differential pressure flow measuring device.

[0016] 2、The air compressor flow measurement method can efficiently and rapidly obtain the running flow of the air compressor, and the flow result can be obtained at any time when the running condition changes, thereby saving the debugging and adapting process of the flow measurement device.

[0017] 3、The air compressor flow measurement method is also applicable to a multi-stage series air compressor system, and can improve the accuracy of the measurement result according to the sampling of the air compressor condition, considering the air compressor motor, frequency conversion loss and system loss of the air compressor. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows.

[0019] Figure 1 Fig. 1 is a structural schematic diagram of an N-stage series air compressor system. DETAILED DESCRIPTION

[0020] The present application will be described in more detail below by means of a preferred embodiment and in conjunction with the drawings, but the present application is not limited in scope by the described embodiments.

[0021] The present application provides an air compressor flow measurement method based on power, comprising the steps of:

[0022] S01, respectively measuring the inlet gas temperature and the outlet gas temperature in the running process of the air compressor; and calculating the actual total power P of the air compressor s ;

[0023] S02, calculating the work w done by the air compressor on unit mass of air according to the inlet gas temperature and the outlet gas temperature of the air compressor obtained in step S01, w = c p .ΔT = c p (T ont -T in ), and obtaining the mass flow of the air compressor Wherein c p is the constant pressure specific heat capacity, which is 1004 J / (kg.K) for air; ΔT is the temperature difference between the inlet and outlet of the air compressor, K; T out is the outlet gas temperature of the air compressor, unit: K; T in is the inlet gas temperature of the air compressor, unit: K;

[0024] S03, calculating the volume flow Q of the air compressor from the mass flow of the air compressor in step S02 v = Q m *60 / ρ; wherein ρ is the inlet gas density, kg / m 3 .

[0025] In step S01, the process of calculating the total power of the actual operation of the air compressor includes: first, determining the power correction coefficient k1 considering the loss of the motor and the frequency converter, the power correction coefficient k2 considering the loss of the air compressor system, then measuring the total power P of the input of the air compressor through the power instrument, P s =k1P*1000+k2.

[0026] The process of determining the power correction coefficient k1 considering the loss of the motor and the frequency converter, and the power correction coefficient k2 considering the loss of the air compressor system includes: under the operating condition of the air compressor, selecting test points, measuring the input power P t1 and P t2 of the two test points, and calculating the actual total power P z1 and P z2 of the air compressor through the detection of the outlet flow pressure of the air compressor, P z1 =k1P t1 *1000+k2, P z2 =k1P t2 *1000+k2; the values of k1 and k2 are obtained by simultaneous equations. The correction coefficients corresponding to different fan models can also be obtained by fitting the experimental data of the prototype.

[0027] For the N-stage air compressor system in series as shown in Fig. Figure 1 , the work done by each stage of air compressor on unit mass of air is calculated in turn, and substituted into the mass flow formula for calculation wherein T lout represents the outlet temperature of the first stage air compressor, T lin represents the inlet temperature of the first stage air compressor, and T Nout represents the outlet temperature of the Nth stage air compressor, and T Nin represents the inlet temperature of the Nth stage air compressor.

[0028] When the operating condition of the air compressor changes, the display values of the detection instruments are waited to be stable, the parameters are read again, and the above process is repeated to calculate the operating flow of the air compressor under the new condition, and the system can be externally connected to a display instrument for real-time display.

[0029] The present application provides a measuring device based on the above-mentioned air compressor flow measurement method, which comprises a power instrument for measuring the input power of the air compressor, a temperature sensing element for measuring the inlet temperature and outlet temperature of the compressor, and a processor for receiving, storing and processing the measurement data. The corresponding formula calculation program is pre-stored in the processor, and the measurement operation of the air compressor flow is automatically performed according to the received data.

[0030] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A power-based air compressor flow measurement method, characterized by, The method comprises the steps of: S01, respectively, measure the inlet gas temperature and the outlet gas temperature during the operation of the air compressor; and calculate the actual total power P of the air compressor s ; S02, calculating the work w done by the air compressor on unit mass of air from the inlet gas temperature and the outlet gas temperature of the air compressor obtained in step S01, and obtaining the mass flow of the air compressor S03, calculating the volumetric flow rate Q of the air compressor from the mass flow rate of the air compressor of step S02 v = Q m * 60 / p; where p is the inlet gas density, kg / m 3 .

2. A power-based air compressor flow measurement method according to claim 1, wherein, In step In S01, the process of calculating the total actual running power of the air compressor includes: first, determining the power correction coefficient k1 considering the loss of the motor and the frequency converter, the power correction coefficient k2 considering the loss of the air compressor system, and then measuring the total input power P of the air compressor through the power instrument, P s =k1P*1000+k2.

3. A power-based air compressor flow measurement method according to claim 2, wherein, The determination considers the power correction coefficient k1 of motor and frequency converter loss, and the process of considering the power correction coefficient k2 of air compressor system loss includes: selecting test points under the running condition of the air compressor, measuring the input power P t1 and P t2 of the two test points z1 , calculating the actual total power P z2 of the air compressor by detecting the outlet flow pressure of the air compressor, and P z1 =k1P t1 *1000+k2, P z2 =k1P t2 *1000+k2; the values of k1 and k2 are obtained by simultaneous equations.

4. The method of claim 1, wherein, For N-stage series air compressor system, the work done by each stage air compressor on unit mass air is calculated in turn, and substituted into mass flow formula for calculation.

5. A power-based air compressor flow measurement method according to claim 4, wherein, The process of calculating the work done by multi-stage series air compressor system on unit mass air includes: setting temperature sensing elements at the air inlet and outlet of each stage air compressor, measuring the inlet and outlet temperatures in turn, and calculating the work done by each stage air compressor on unit mass air.

6. An air compressor flow measuring device using the power-based air compressor flow measuring method according to any one of claims 1 to 5, characterized by, It comprises a power meter for measuring air compressor input power, temperature sensing elements for measuring compressor inlet and outlet temperatures, and a processor for receiving, storing and processing measurement data.

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