High-temperature large fan performance testing device

Abstract

The invention belongs to the technical field of fan performance testing, and discloses a high-temperature large fan performance testing device which is characterized in that a testing pipeline is of a backflow type and comprises a tested fan, an air heating section, an air volume measuring pipe section, an air volume adjusting valve, a flexible connecting pipe section and a pressure balance pipe. The power of an electric heating pipe in the air heating section is continuously adjustable, and the air temperature is controlled at the required temperature. A part of the pipeline adopts a detachable heat preservation mode, and when the air temperature exceeds the target temperature due to airflow friction heating, a part of the heat preservation structure can be detached to reduce the air temperature. The air volume is measured by adopting a flow nozzle method, and the flow measurement range is expanded by adopting a replaceable secondary contraction section. The pipeline comprises a flexible connection pipe section, so that the secondary contraction section and the tested fan are convenient to disassemble and assemble, and thermal expansion deformation of the pipeline is absorbed. The pressure balance pipe can maintain pressure balance inside and outside the pipeline when the air temperature changes. The testing device has the advantages of being high in air temperature control precision, small in pipeline flow resistance and low in energy consumption.

Description

Technical Field

[0001] The invention belongs to the technical field of fan performance testing, and in particular relates to a high-temperature large-scale fan performance testing device. Background Art

[0002] The working air temperature of fire smoke exhaust fans and some special fans in the chemical industry can reach above 500℃, and the air volume can reach above 100000m3 / h. For these high-temperature large fans that transport high-temperature smoke (or other gases), mechanical operation and air performance tests are required before leaving the factory.

[0003] Compared with normal temperature conditions, the design and construction of high-temperature large-scale fan performance test equipment needs to solve problems such as air heating, test pipe insulation, wind temperature control, high-temperature air volume measurement, and pipeline and structure safety caused by high-temperature expansion deformation. There are many air volume measurement methods available under normal temperature conditions, such as conical inlet, arc inlet, orifice plate, Venturi nozzle and Pitot tube transverse movement method; while high-temperature devices are generally return air ducts, the first two air volume test methods are not applicable, and the latter three methods can be used in high-temperature devices in theory, but requirements such as easy replacement, reliable sealing and small flow resistance should be considered. In terms of wind temperature, controlling the wind temperature near the target temperature is a basic requirement of the test device. In order to achieve the required high temperature and energy saving, the test pipe needs to be insulated. For the return test pipe, when the power of the tested fan is very large, the friction of the air flow may cause excessive temperature rise, and sufficient heat dissipation capacity must be considered to maintain temperature stability.

[0004] Judging from the existing technology, the design technology of high-temperature large-scale fan test system is far from mature. Whether it is from the perspective of improving the level of wind temperature control or the convenience of testing, there is still a lot of room for improvement. Summary of the invention

[0005] The purpose of the present invention is to provide a high-temperature large-scale fan performance testing device to solve the above-mentioned technical problems.

[0006] In order to solve the above technical problems, the specific technical solution of a high-temperature large-scale fan performance testing device of the present invention is as follows:

[0007] A high-temperature large-scale fan performance test device comprises a tested fan, a fan outlet connecting short pipe, a flow straightener 1, a downstream air duct, a connecting pipe, a flow straightener 2, an air volume measuring pipe section, a flexible connecting pipe section 1, an air volume regulating valve, a pressure balancing pipe, an air heating section, a flow straightener 3, an upstream air duct, a flexible connecting pipe section 2 and a fan inlet connecting short pipe, which are connected end to end in sequence. The device is characterized in that a pressure taking pipe and a temperature sensor are installed at one position in the middle section of the upstream air duct to obtain the wind pressure and wind temperature of this section; a pressure taking pipe and a temperature sensor are installed at two positions in the middle section of the downstream air duct to obtain the wind pressure and wind temperature of this section; a pressure taking pipe and a temperature sensor are installed at three positions in the middle section of the air volume measuring pipe section to obtain the wind pressure and wind temperature of this section, a pressure taking pipe and a temperature sensor are installed at four positions in the section at the rear end of the section three to obtain the wind temperature, and the differential pressure between the section three and the section four is obtained.

[0008] Furthermore, the air volume measurement pipe section has a replaceable pipe section.

[0009] Furthermore, an electric heating tube is installed in the air heating section to heat the air, and the heating power is continuously adjustable.

[0010] Furthermore, the air heating section is located upstream of the fan.

[0011] Furthermore, the test duct fan outlet connecting short pipe, fan inlet connecting short pipe, air volume regulating valve and replaceable pipe section have a detachable insulation structure; the flexible connecting pipe section 1, flexible connecting pipe section 2 and replaceable pipe section connecting flange are not insulated; the rest of the test device adopts a non-detachable fixed insulation structure.

[0012] Furthermore, the replaceable pipe section is a secondary contraction section or a straight pipe.

[0013] Furthermore, an electric valve is installed on the pressure balancing pipe. When the pressure in the test pipeline rises and exceeds the set upper limit pressure due to the increase in temperature, the valve is opened to discharge part of the hot air until the pressure inside the pipeline is balanced with the external environment; when the pressure in the pipeline is lower than the set lower limit pressure, the valve is opened, and external cold air enters the pipeline, so that the pressure inside and outside the test pipeline is balanced.

[0014] Furthermore, the flow straightener 1, flow straightener 2 and flow straightener 3 are respectively installed before the downstream air duct, the air volume measurement pipe section and the pressure and temperature measurement section of the upstream air duct.

[0015] The high-temperature large-scale fan performance testing device of the present invention has the following advantages:

[0016] 1) The detachable insulation structure design allows for flexible adjustment of heat dissipation. Combined with the stepless adjustment of electric heating power, it can achieve the required high temperature and ensure that the air temperature is controlled at the target temperature. At the same time, pipe insulation reduces heat dissipation, reduces heating energy consumption, improves energy saving, and makes the test environment more friendly.

[0017] 2) The air volume measurement is carried out by using the contraction nozzle based on the throttling principle, which can adapt to high temperature conditions and has high air volume measurement accuracy. Combined with the replaceable secondary contraction section design, the device can be applied to the testing of fans of different specifications with a large air volume range.

[0018] 3) The soft connection pipe section in the test pipeline, on the one hand, facilitates the disassembly and assembly of the secondary contraction section and the fan under test, and on the other hand, can absorb the thermal expansion and deformation of the test pipeline to ensure the safety of the equipment.

[0019] 4) A pressure balance pipe is designed to discharge hot air in the pipe when the temperature and pressure rise, and to draw cold air into the pipe when the temperature and pressure drop, thereby maintaining the pressure balance inside and outside the pipe and ensuring the safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a high-temperature large-scale fan performance testing device of the present invention;

[0021] Figure 2 It is a schematic diagram of the heat preservation structure of the high-temperature large-scale fan performance test device of the present invention;

[0022] Explanation of the markings in the figure: 1. Fan under test; 2. Fan outlet connecting short pipe; 3. Flow straightener 1; 4. Downstream air duct; 5. Connecting pipe; 6. Flow straightener 2; 7. Air volume measurement pipe section; 71. Replaceable pipe section; 711. Secondary contraction section; 712. Straight pipe; 8. Flexible connecting pipe section 1; 9. Air volume regulating valve; 10. Pressure balancing pipe; 11. Air heating section; 12. Flow straightener 3; 1. Upstream air duct; 14. Flexible connecting pipe section 2; 15. Fan inlet connecting short pipe. DETAILED DESCRIPTION

[0023] In order to better understand the purpose, structure and function of the present invention, a high-temperature large-scale fan performance testing device of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the structure of a high-temperature large fan performance test device.

[0025] A high-temperature large-scale fan performance test device of the present invention comprises a tested fan 1, a fan outlet connecting short pipe 2, a flow straightener 1 3, a downstream air duct 4, a connecting pipeline 5, a flow straightener 2 6, an air volume measuring pipe section 7, a flexible connecting pipe section 1 8, an air volume regulating valve 9, a pressure balancing pipe 10, an air heating section 11, a flow straightener 3 12, an upstream air duct 1, a flexible connecting pipe section 2 14 and a fan inlet connecting short pipe 15, which are connected end to end in sequence. The air volume measuring pipe section 7 is designed with a replaceable pipe section 71.

[0026] In order to ensure the strength of the pipeline and its corrosion and rust resistance at a high temperature of 600°C, high-temperature resistant stainless steel is used as the pipeline material.

[0027] A pressure-taking tube and a temperature sensor are installed at one location in the middle section of the upstream air duct 13 to obtain the wind pressure P1 and wind temperature T1 of this section; a pressure-taking tube and a temperature sensor are installed at two locations in the middle section of the downstream air duct 4 to obtain the wind pressure P2 and wind temperature T2 of this section; a pressure-taking tube and a temperature sensor are installed at three locations in the middle section of the air volume measurement pipe section 7 to obtain the wind pressure P3 and wind temperature T3 of this section, and a pressure-taking tube and a temperature sensor are installed at four locations in the section at the rear end of section three to obtain the wind temperature T4, and the differential pressure ΔP between section three and section four is obtained.

[0028] An electric heating tube is installed in the air heating section 11 to heat the air, and the heating power is continuously adjustable to control the air temperature.

[0029] Assume that the test pipeline system is in thermal equilibrium and the air temperature is stable at temperature T. At this time, the heat generation is equal to the heat dissipation. The heat generation includes two parts: one is the electric heating power of the electric heating tube, and the other is the heat generation power of the air flow friction. The thermal balance equation can be described by formula (1), that is,

[0030] P e +P f =Ak(TT a ) (1)

[0031] Where:

[0032] P e - Electric heating power;

[0033] P f - Air flow friction heat generation power;

[0034] A – heat transfer area;

[0035] k - equivalent heat transfer coefficient;

[0036] T – wind temperature;

[0037] T a - Ambient air temperature.

[0038] The heat generated by friction of the airflow on the left side of formula (1) is Pf The right side is the heat dissipation, and the equivalent heat transfer coefficient k is related to the air volume, air temperature, insulation conditions, etc. Theoretically, by adjusting the electric heating power P e The size can stabilize the system temperature at T and achieve thermal equilibrium. In actual testing, the focus is on the wind temperature at the fan under test, so the average temperature of section 1 and section 2 is T m (=(T1+T2) / 2) is the control target for wind temperature feedback control, where T1 is the temperature of section 1, and T2 is the temperature of section 2.

[0039] Figure 1 In the test, the airflow direction in the test pipeline is counterclockwise, the air heating section 11 is located upstream of the fan, the fan 1 under test is located in the section of the entire pipeline with higher air temperature, the air heating section 11 is close to the fan under test, and the air temperature control is relatively sensitive.

[0040] Figure 2 This is a schematic diagram of the insulation structure of a high-temperature large fan performance test device.

[0041] In order to reduce the heat dissipation, the pipe needs to be insulated. This can reduce the heating power consumption on the one hand, and reduce the temperature of the outer wall of the pipe on the other hand, making the test environment more friendly. For the pipe insulation design, one factor needs to be considered. According to formula (1), if the insulation is done very well, the heat transfer coefficient k is very small, even if the electric heating heat generation power P e If the temperature T is zero, it will be very high and may exceed the target wind temperature, so the wind temperature cannot be controlled at the required temperature. In order to avoid this problem, the pipe insulation adopts a combination of fixed structure and detachable structure. One part of the pipe insulation is a fixed non-detachable structure, and the other part is a detachable structure. When the heat generated by air friction is large and causes the temperature rise to exceed the target temperature, a part of the pipe insulation is removed (the effect is equivalent to increasing the equivalent heat transfer coefficient k), so that the wind temperature can be stabilized at the required temperature. There is also a small part of the pipe that can be uninsulated, that is, the high-temperature pipe wall is exposed to dissipate heat.

[0042] The design principle of the proportion of the detachable insulation part is to ensure that the air temperature is lower than the target temperature without starting the electric heating of the air heating section. The specific insulation method in the present invention is: the test pipeline fan outlet connecting short pipe 2, the fan inlet connecting short pipe 15, the air volume regulating valve 9 and the replaceable pipe section 71 adopt a detachable insulation structure; the flexible connection pipe section 1 8, the flexible connection pipe section 2 14 and the replaceable pipe section 71 connection flange are not insulated; the other parts of the pipeline adopt a non-detachable fixed insulation structure.

[0043] The air volume measurement section 7 is a contraction pipe (the air flow flows counterclockwise). The air flow in the contraction section is equivalent to the nozzle flow. According to the working principle of the flow nozzle, the air volume can be calculated by measuring the pressure difference ΔP before and after the contraction section. The mass flow formula of the flow nozzle is

[0044]

[0045] Where:

[0046] Q m - Air mass flow;

[0047] d - diameter of the outlet of the contraction section;

[0048] ρ - air density of the measuring section, determined according to the temperature and pressure of the measuring section;

[0049] α - flow coefficient;

[0050] ε - expansion coefficient, when the differential pressure ΔP is small, ε≈1.

[0051] From formula (2), we can know that the flow rate is proportional to the 1 / 2 power of the differential pressure, and vice versa, the differential pressure is proportional to the square of the flow rate. Therefore, the flow range ratio cannot be too large, otherwise the differential pressure variation range is too large, which will lead to a sharp increase in measurement error (for example, if the range ratio is 10 times, the differential pressure variation range is 100 times, so the differential pressure measurement accuracy is difficult to guarantee at low flow rates, and the measurement error will be large). For this reason, the range ratio of throttling flowmeters (nozzles are a type of throttling device) is generally small.

[0052] In order to expand the range ratio, two solutions can be considered. One is to use multiple micro differential pressure transmitters with different ranges, and the other is to change the nozzle contraction ratio, that is, to use a replaceable pipe section. The present invention adopts a two-stage contraction solution, that is, the replaceable pipe section 71 of the air volume measurement pipe section 7 is designed to be replaceable. For the test of a fan with a smaller air volume, a two-stage contraction section 711 with a smaller outlet diameter is used to measure the air volume; for a fan with a large air volume, there is no need to perform a two-stage contraction, but a straight pipe 712 is used for connection (such as Figure 1 shown).

[0053] For example, for a test duct with a maximum flow rate of 120,000 m3 / h and an air temperature of 600°C, according to formula (2), three air volume measurement sections with contraction ratios can be used, as shown in Table 1.

[0054] Table 1 Comparison table of air volume in air volume measurement section

[0055]

[0056] A flexible connecting pipe section 1 8 is designed downstream of the air volume measurement pipe section 7, which is used to facilitate the disassembly and assembly of the replaceable pipe section 71 in the air volume measurement pipe section 7 and to absorb the high-temperature thermal expansion deformation of the test pipe. For the same reason, a flexible connecting pipe section 2 14 is designed between the upstream air duct 13 and the fan inlet connecting short pipe 15, which is used to reduce the installation difficulty of the fan 1 under test and absorb the thermal expansion deformation of the pipes on both sides.

[0057] A pressure balance pipe 10 is designed between the air volume regulating valve 9 and the air heating section 11, and an electric valve is installed on the pressure balance pipe 10. Its function is: when the pressure in the test pipeline exceeds the set upper limit pressure due to the increase in temperature, the valve is opened to discharge part of the hot air until the pressure inside the pipeline is balanced with the external environment; when the pressure in the pipeline is lower than the set lower limit pressure, the valve is opened to allow external cold air to enter the pipeline, and the pressure inside and outside the test pipeline is balanced.

[0058] The purpose of the air volume regulating valve 9 is to change the flow resistance of the test pipeline and adjust the air volume point during the fan test.

[0059] The function of the flow straightener is to make the flow in the downstream pipeline more uniform. The flow straightener should be installed upstream of the section where pressure and temperature measurement are required. Figure 1 The middle flow straightener 1 3 , the flow straightener 2 6 and the flow straightener 3 12 are installed before the pressure and temperature measurement sections of the downstream air duct 4 , the air volume measurement pipe section 7 and the upstream air duct 13 , respectively.

[0060] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A high-temperature large-scale fan performance test device, comprising a fan to be tested (1), a fan outlet connecting short pipe (2), a flow straightener 1 (3), a downstream air duct (4), a connecting pipe (5), a flow straightener 2 (6), an air volume measuring pipe section (7), a flexible connecting pipe section 1 (8), an air volume regulating valve (9), a pressure balancing pipe (10), an air heating section (11), a flow straightener 3 (12), an upstream air duct (1), a flexible connecting pipe section 2 (14) and a fan inlet connecting short pipe (15) connected in sequence end to end, characterized in that: A pressure-taking tube and a temperature sensor are installed at one point in the middle section of the upstream air duct (1) to obtain the wind pressure and wind temperature of the section; a pressure-taking tube and a temperature sensor are installed at two points in the middle section of the downstream air duct (4) to obtain the wind pressure and wind temperature of the section; a pressure-taking tube and a temperature sensor are installed at three points in the middle section of the air volume measurement pipe section (7) to obtain the wind pressure and wind temperature of the section, and a pressure-taking tube and a temperature sensor are installed at four points in the section at the rear end of section three to obtain the wind temperature, and to obtain the differential pressure between section three and section four.

2. The high-temperature large-scale fan performance testing device according to claim 1 is characterized in that: The air volume measurement pipe section (7) has a replaceable pipe section (71).

3. The high-temperature large-scale fan performance testing device according to claim 1 is characterized in that: An electric heating tube is installed in the air heating section (11) to heat the air, and the heating power is continuously adjustable.

4. The high-temperature large-scale fan performance testing device according to claim 1 is characterized in that: The air heating section (11) is located upstream of the fan.

5. The high temperature large fan performance testing device according to claim 1, characterized in that: The fan outlet connecting short pipe (2), the fan inlet connecting short pipe (15), the air volume regulating valve (9) and the replaceable pipe section (71) of the test pipeline are provided with a detachable heat-insulating structure; the connection flanges of the flexible connecting pipe section 1 (8), the flexible connecting pipe section 2 (14) and the replaceable pipe section (71) are not insulated; and the rest of the test device adopts a non-detachable fixed heat-insulating structure.

6. The high temperature large fan performance testing device according to claim 2, characterized in that: The replaceable pipe section (71) is a secondary contraction section (711) or a straight pipe (712).

7. The high temperature large fan performance testing device according to claim 1, characterized in that: The pressure balance pipe (10) is provided with an electric valve. When the pressure in the test pipe rises to a value exceeding a set upper limit pressure due to a temperature rise, the valve is opened to discharge part of the hot air until the pressure inside the pipe is balanced with the pressure of the external environment. When the pressure inside the pipe is lower than the set lower limit pressure, the valve is opened to allow external cold air to enter the pipe, and the pressure inside and outside the test pipe is balanced.

8. The high-temperature large-scale fan performance testing device according to claim 1 is characterized in that: The flow straightener 1 (3), flow straightener 2 (6) and flow straightener 3 (12) are respectively installed before the pressure and temperature measurement section of the downstream air duct (4), the air volume measurement pipe section (7) and the upstream air duct (1).

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