A nuclear-grade certified low-pressure DC gear fuel pump unit

Abstract

The present invention specifically relates to a low-voltage DC gear fuel pump unit that has passed nuclear-grade certification, including an equipment mounting base and a low-voltage DC gear fuel pump mounted on the equipment mounting base, wherein a plurality of low-voltage DC gear fuel pumps are arranged in parallel. The low-voltage DC gear fuel pump unit of the present invention has a modular design and arrangement that allows for rapid on-site equipment installation, shortening the original installation period of several days to a few hours, thereby improving work efficiency. At the same time, rapid disassembly and assembly is also conducive to comprehensive maintenance of the pump set at a later stage, and if there is a fault, it can be directly replaced, greatly improving maintenance efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of gear fuel pumps, in particular to a low-voltage DC gear fuel pump unit that has passed nuclear grade certification. Background Art

[0002] The emergency diesel generator of the 320MWe unit of the Qin No. 1 nuclear power plant of China National Nuclear Corporation is equipped with a DC fuel pump group, which consists of two DC fuel pumps of the same model, one for use and one for backup. The DC fuel pump consists of a fuel gear fuel pump and a matching DC motor. When the nuclear power plant loses external power and the emergency diesel generator is started, the DC fuel pump group is used to ensure the pre-supply oil pressure during the unit startup and provide the fuel supply required when the unit is running at full power, thereby ensuring the ability of the emergency diesel generator set to perform safety-related functions.

[0003] According to the technical specifications, the low-voltage DC fuel pump is a safety level 3 pump, and the pump drive motor is a 1E DC motor. The seismic category of the pump unit is Class I SSE. The original DC fuel pump of Qinyi Factory has not been nuclear grade certified, and there are weaknesses in the periodic safety review PSR, which cannot ensure that it can perform its intended functions in the event of a design basis event, thereby supporting the emergency diesel generator to perform nuclear safety functions. Summary of the invention

[0004] Based on this, it is necessary to provide a low-voltage DC gear fuel pump unit that has passed the nuclear grade appraisal in order to address the problem of periodic safety review PSR weaknesses in existing low-voltage DC fuel pumps. The low-voltage DC gear fuel pump unit has passed the appraisal of nuclear-grade low-voltage DC gear fuel pumps and 1E-level DC motors and meets nuclear safety requirements. At the same time, it can eliminate the periodic safety review PSR weaknesses caused by the low-voltage DC fuel pump, improve the equipment reliability of the emergency diesel engine, and ensure the in-depth defense capability of the nuclear power plant.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A low-pressure DC gear fuel pump unit that has passed nuclear grade appraisal comprises an equipment mounting base and a low-pressure DC gear fuel pump mounted on the equipment mounting base, wherein a plurality of low-pressure DC gear fuel pumps are arranged in parallel.

[0007] Furthermore, the equipment mounting base is a movable equipment mounting base made of a steel plate.

[0008] Furthermore, the equipment installation base is a rectangular plate or a square plate formed by welding steel plates, and at least two groups of lifting ears are symmetrically welded on at least one group of opposite sides of the equipment installation base.

[0009] Furthermore, the low-voltage DC gear fuel pump includes a low-voltage DC motor and a gear fuel pump connected via a coupling.

[0010] Furthermore, the electromagnetic parameters of the low-voltage DC motor are designed according to the torque characteristics of the gear fuel pump, and a small number of series-connected shunt motors are used, thereby meeting the requirements for rapid starting of nuclear-grade emergency diesel generators in nuclear power plants.

[0011] Furthermore, a U-shaped shield is installed outside the coupling.

[0012] Furthermore, a plurality of equipment mounting bosses are installed on the equipment mounting base, and a low-voltage DC gear fuel pump is installed on each equipment mounting boss. The position of the equipment mounting boss is set according to the installation requirements of the low-voltage DC gear fuel pump in the equipment filling space.

[0013] Furthermore, the equipment mounting base is connected to the equipment mounting boss by welding.

[0014] Furthermore, the equipment mounting boss is connected to the threaded bolts of the low-pressure DC gear fuel pump.

[0015] Furthermore, an internal threaded mounting hole is provided on the mounting panel of the equipment mounting boss, and the mounting through hole on the base of the low-pressure DC gear fuel pump is fixedly connected with the internal threaded mounting hole by bolts, and the low-pressure DC gear fuel pump is installed on the mounting panel through the fixed connection.

[0016] Furthermore, the plurality of low-pressure DC gear fuel pumps are arranged in parallel via a fuel pipeline, and the bottom of the fuel pipeline is connected to the equipment mounting base via a bracket.

[0017] Furthermore, the fuel pipeline includes an inlet pipe, an outlet pipe, an inlet multi-way pipe, and an outlet multi-way pipe, and the inlet multi-way pipe and the outlet multi-way pipe are provided with a plurality of branch pipes matching the number of low-pressure DC gear fuel pumps; the inlet pipe is connected to a branch pipe of the inlet multi-way pipe, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe; each of the other branch pipes of the inlet multi-way pipe is connected to the pump inlet of a low-pressure DC gear fuel pump; each of the other branch pipes of the outlet multi-way pipe is connected to the pump outlet of a low-pressure DC gear fuel pump.

[0018] Furthermore, a stop valve is provided at the pump inlet of each low-pressure DC gear fuel pump, and a check valve is provided at the pump outlet of each low-pressure DC gear fuel pump; among the other branch pipes of the inlet multi-way pipe, each branch pipe is connected to the stop valve of a low-pressure DC gear fuel pump; among the other branch pipes of the outlet multi-way pipe, each branch pipe is connected to the check valve of a low-pressure DC gear fuel pump.

[0019] Furthermore, the pipes of the fuel line are connected via flanges, the pipes of the fuel line and the valve are both connected via flanges, and the pipes of the fuel line and the gear fuel pump are both connected via flanges.

[0020] Furthermore, two low-pressure DC gear fuel pumps are arranged in parallel.

[0021] A method for nuclear grade identification of a low-voltage DC gear fuel pump unit comprises the following steps:

[0022] 1. Gear fuel pump unit performance test;

[0023] 2. Low voltage DC motor performance test;

[0024] 3. Assemble low-voltage DC gear fuel pump;

[0025] 4. Low-voltage DC gear fuel pump performance test;

[0026] 5. Assemble the low-voltage DC fuel pump unit;

[0027] 6. Low-voltage DC fuel pump unit performance test.

[0028] Furthermore, before step 1, the method further includes the following steps: initial inspection of the low-voltage DC motor and the gear fuel pump assembly.

[0029] Furthermore, in step 1, the gear fuel pump group performance test includes the following steps: adjusting the outlet pressure of the gear fuel pump group through the gear fuel pump outlet check valve, measuring the head, flow, shaft power and speed of the gear fuel pump at more than 6 different discharge pressure operating points according to the requirements of JB / T6434 B-level accuracy, and drawing a PQ curve; adjusting the opening of the gear fuel pump outlet check valve to make the outlet pressure of the gear fuel pump group reach the rated value, and measuring the current of the low-voltage DC motor; adjusting the opening of the gear fuel pump outlet check valve to make the outlet flow of the gear fuel pump group reach the rated value, and measuring the current of the low-voltage DC motor; measuring the flow of the gear fuel pump group at the rated pressure under the limit condition of the input power supply voltage -15%; measuring the flow of the gear fuel pump group at the rated pressure under the limit condition of the input power supply voltage +10%.

[0030] Furthermore, in step 2, the low voltage DC motor performance test includes the following steps: a low voltage DC motor benchmark performance test, a low voltage DC motor thermal aging test, a low voltage DC motor vibration aging test, and a low voltage DC motor electrical stress aging test.

[0031] Furthermore, the low-voltage DC motor benchmark performance test includes the following steps: low-voltage DC motor benchmark performance test before detection, measurement of the insulation resistance of the winding to the low-voltage DC motor casing and between the windings, low-voltage DC motor load test, low-voltage DC motor withstand voltage test, and low-voltage DC motor inspection and analysis.

[0032] Further, in step 6, the low-voltage DC fuel pump unit test includes the following steps: a low-voltage DC gear fuel pump unit benchmark performance test, a low-voltage DC gear fuel pump unit seismic test, and a low-voltage DC gear fuel pump unit benchmark performance test after the seismic test.

[0033] Furthermore, the low-voltage DC gear fuel pump unit benchmark performance test includes the following steps: measurement of the insulation resistance of the winding to the DC motor housing and between the windings, a withstand voltage test of the low-voltage DC gear fuel pump unit, and inspection and analysis of the low-voltage DC gear fuel pump unit.

[0034] Furthermore, the seismic test of the low-voltage DC gear fuel pump unit includes the following steps: an exploration test before the seismic test of the low-voltage DC gear fuel pump unit, a seismic test of the low-voltage DC gear fuel pump unit, an inspection during the seismic process of the low-voltage DC gear fuel pump unit, and an inspection after the seismic process of the low-voltage DC gear fuel pump unit.

[0035] Beneficial technical effects of the present invention:

[0036] 1. The low-voltage DC gear fuel pump unit of the present invention adopts the concept of parallel connection and modular design of low-voltage DC gear fuel pump groups, integrates low-voltage DC gear fuel pump groups and pipeline valves and other components on a movable base, and realizes modular design and layout. The modular design and layout can quickly install equipment on site, shortening the original installation period of several days to a few hours, thereby improving work efficiency. At the same time, rapid disassembly and assembly is also conducive to comprehensive maintenance of the pump group in the later stage. If there is a fault, it can be directly replaced, greatly improving maintenance efficiency.

[0037] 2. The low-pressure DC gear fuel pump unit of Example 1 installs two low-pressure DC gear fuel pumps and their inlet and outlet valves on one equipment platform. First, it can meet the use requirements of one low-pressure DC gear fuel pump for use and one for backup, reducing the use risk of the system. Secondly, the modular design can quickly install the equipment on site, shortening the original installation period of several days to a few hours, thereby improving work efficiency. At the same time, rapid disassembly and assembly is also conducive to comprehensive maintenance of the pump group in the later stage. If there is a fault, it can be directly replaced, greatly improving the maintenance efficiency.

[0038] 3. The low-voltage DC gear fuel pump and DC motor of the present invention have passed the appraisal of nuclear-grade low-voltage DC gear fuel pump and 1E-grade DC motor, and the appraisal results are qualified and meet the nuclear safety requirements. At the same time, the equipment reliability of the emergency diesel engine is improved, and the depth defense capability of the nuclear power plant is guaranteed.

[0039] 4. The low-voltage DC gear fuel pump unit of the present invention can not only be applied to emergency diesel generator sets in nuclear power plants, but also can be used as a matching oil pump for nuclear-grade equipment. At the same time, the nuclear-grade identification ideas and methods of the present invention have good practical guiding significance for the development and identification of other nuclear-grade equipment in nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A top view of a low-voltage DC gear pump unit that has passed nuclear grade certification according to Example 1;

[0041] Figure 2 This is a front view of the low-voltage DC gear pump unit that has passed the nuclear grade certification of Example 1.

[0042] In the figure, 1. low voltage DC motor; 2. gear fuel pump; 3. check valve; 4. stop valve; 5-A. inlet flange; 5-B outlet flange; 6. equipment mounting base; 7. lifting ear; 8. equipment mounting boss; 9. coupling. DETAILED DESCRIPTION

[0043] A low-pressure DC gear fuel pump unit that has passed nuclear grade certification comprises an equipment mounting base and a low-pressure DC gear fuel pump mounted on the equipment mounting base 6, wherein a plurality of low-pressure DC gear fuel pumps are arranged in parallel.

[0044] Furthermore, the equipment mounting base 6 is a movable equipment mounting base made of a steel plate.

[0045] Furthermore, the equipment installation base 6 is a rectangular plate or a square plate formed by welding steel plates, and at least two groups of lifting ears 7 are symmetrically welded on at least one group of opposite sides of the equipment installation base 6.

[0046] Furthermore, the low-voltage DC gear fuel pump includes a low-voltage DC motor 1 and a gear fuel pump 2 connected via a coupling 9 .

[0047] Furthermore, the electromagnetic parameters of the low-voltage DC motor 1 are designed according to the torque characteristics of the gear fuel pump 2, and a small number of series-connected shunt motors are used, thereby meeting the requirements for rapid starting of nuclear-grade emergency diesel generators in nuclear power plants.

[0048] Furthermore, a U-shaped shield is installed outside the coupling 9.

[0049] Furthermore, a plurality of equipment mounting bosses 8 are installed on the equipment mounting base 6, and a low-voltage DC gear fuel pump is installed on each equipment mounting boss 8. The position of the equipment mounting boss 8 is set according to the installation requirements of the low-voltage DC gear fuel pump in the equipment filling space.

[0050] Furthermore, the equipment mounting base 6 is connected to the equipment mounting boss 8 by welding.

[0051] Furthermore, the equipment mounting boss 8 is threadedly bolted to the low-pressure DC gear fuel pump 2 .

[0052] Furthermore, an internal threaded mounting hole is provided on the mounting panel of the equipment mounting boss 8, and the mounting through hole on the base of the low-pressure DC gear fuel pump is fixedly connected with the internal threaded mounting hole through bolts, and the low-pressure DC gear fuel pump is installed on the mounting panel through the fixed connection.

[0053] Furthermore, the plurality of low-pressure DC gear fuel pumps are arranged in parallel via a fuel pipeline, and the bottom of the fuel pipeline is connected to the equipment mounting base 6 via a bracket.

[0054] Furthermore, the fuel pipeline includes an inlet pipe, an outlet pipe, an inlet multi-way pipe, and an outlet multi-way pipe, and the inlet multi-way pipe and the outlet multi-way pipe are provided with a plurality of branch pipes matching the number of low-pressure DC gear fuel pumps; the inlet pipe is connected to a branch pipe of the inlet multi-way pipe, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe; each of the other branch pipes of the inlet multi-way pipe is connected to the pump inlet of a low-pressure DC gear fuel pump; each of the other branch pipes of the outlet multi-way pipe is connected to the pump outlet of a low-pressure DC gear fuel pump.

[0055] Furthermore, a stop valve 4 is provided at the pump inlet of each low-pressure DC gear fuel pump, and a check valve 3 is provided at the pump outlet of each low-pressure DC gear fuel pump; among the other branch pipes of the inlet multi-way pipe, each branch pipe is connected to the stop valve 4 of a low-pressure DC gear fuel pump; among the other branch pipes of the outlet multi-way pipe, each branch pipe is connected to the check valve 3 of a low-pressure DC gear fuel pump.

[0056] Furthermore, the pipes of the fuel line are connected to each other through flanges, the pipes of the fuel line and the valves are connected to each other through flanges, and the pipes of the fuel line and the gear fuel pump 2 are connected to each other through flanges.

[0057] Furthermore, the inlet pipe is connected to a branch pipe of the inlet multi-way pipe through an inlet flange 5-A, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe through an outlet flange 5-B.

[0058] Furthermore, two low-pressure DC gear fuel pumps are arranged in parallel.

[0059] A method for nuclear grade identification of a low-voltage DC gear fuel pump unit comprises the following steps:

[0060] 1. Gear fuel pump unit performance test;

[0061] 2. Low voltage DC motor performance test;

[0062] 3. Assemble low-voltage DC gear fuel pump;

[0063] 4. Low-voltage DC gear fuel pump performance test;

[0064] 5. Assemble the low-voltage DC fuel pump unit;

[0065] 6. Low-voltage DC fuel pump unit performance test;

[0066] Furthermore, before step 1, the method further includes the following steps: initial inspection of the low-voltage DC motor 1 and the gear fuel pump assembly.

[0067] Further, step 1 includes the following steps: adjusting the outlet pressure of the gear fuel pump group through the outlet check valve 3 of the gear fuel pump 2, measuring the head, flow rate, shaft power and speed value of the gear fuel pump 2 at more than 6 different discharge pressure operating points including a zero pressure point and a rated discharge pressure point according to the requirements of JB / T6434 B-level accuracy, and drawing a PQ curve;

[0068] By adjusting the opening of the check valve 3 at the outlet of the gear fuel pump 2, the outlet pressure of the gear fuel pump group reaches the rated value, and the current of the DC motor is measured;

[0069] By adjusting the opening of the check valve 3 at the outlet of the gear fuel pump 2, the outlet flow of the gear fuel pump group reaches the rated value, and the current of the DC motor is measured;

[0070] Under the input power supply voltage limit condition of -15%, measure the flow rate of the gear fuel pump group at rated pressure;

[0071] Under the input power supply voltage limit condition of +10%, measure the flow rate of the gear fuel pump group at rated pressure.

[0072] Furthermore, in step 2, the low voltage DC motor performance test includes the following steps: a low voltage DC motor benchmark performance test, a low voltage DC motor thermal aging test, a low voltage DC motor vibration aging test, and a low voltage DC motor electrical stress aging test.

[0073] Furthermore, the low-voltage DC motor benchmark performance test includes the following steps: pre-test detection of the low-voltage DC motor benchmark performance test, measurement of the insulation resistance of the winding to the low-voltage DC motor casing and between the windings in cold and hot states, low-voltage DC motor load test, low-voltage DC motor withstand voltage test, and inspection and analysis of the low-voltage DC motor.

[0074] Low-voltage DC motor 1 is subjected to low-voltage DC motor thermal aging test, low-voltage DC motor vibration aging test and low-voltage DC motor electrical stress aging test according to IEEE 334-1994 standard requirements. In the low-voltage DC motor thermal aging test, the thermal aging temperature is 220°C and the aging time is 596 hours. In the low-voltage DC motor vibration aging test, an acceleration of 1.5g is used to vibrate the DC motor for 1 hour. In the low-voltage DC motor electrical stress aging test, a voltage of 2 / 3 of the sum of 2 times the rated voltage plus 1000V is applied for 1 minute.

[0075] The nuclear-grade DC fuel pump group of the emergency diesel generator has significant thermal aging, mechanical stress aging and electrical stress aging mechanisms, and earthquake is the only design basis event. Further, in step 6, the low-voltage DC fuel pump unit test includes the following steps: low-voltage DC gear fuel pump unit benchmark performance test, low-voltage DC gear fuel pump unit seismic test, and low-voltage DC gear fuel pump unit benchmark performance test after seismic test.

[0076] Furthermore, the low-voltage DC gear fuel pump unit benchmark performance test includes the following steps: measurement of the insulation resistance of the winding to the low-voltage DC motor housing and between the windings in cold and hot states, a withstand voltage test of the low-voltage DC gear fuel pump unit, and inspection and analysis of the low-voltage DC gear fuel pump unit.

[0077] Furthermore, the seismic test of the low-voltage DC gear fuel pump unit includes the following steps: an exploration test before the seismic test of the low-voltage DC gear fuel pump unit, a seismic test of the low-voltage DC gear fuel pump unit, an inspection during the seismic process of the low-voltage DC gear fuel pump unit, and an inspection after the seismic process of the low-voltage DC gear fuel pump unit.

[0078] During the seismic test of the low-voltage DC gear fuel pump unit, the low-voltage DC gear fuel pump unit shall be subjected to 5 consecutive OBE vibrations to simulate the cumulative effect of earthquake fatigue. After the 5 OBE tests, the low-voltage DC gear fuel pump unit shall be subjected to one SSE vibration.

[0079] The low-voltage DC gear fuel pump unit of the present invention is subjected to nuclear grade certification using the nuclear grade certification method. The low-voltage DC gear fuel pump unit of the present invention ensures structural integrity and safety function operability at all stages of the certification.

[0080] The present invention is further described in detail below in conjunction with embodiments and drawings.

[0081] Example 1

[0082] A low-pressure DC gear fuel pump unit that has passed nuclear grade certification comprises an equipment mounting base 6 and a low-pressure DC gear fuel pump mounted on the equipment mounting base 6, wherein two low-pressure DC gear fuel pumps are arranged in parallel.

[0083] Furthermore, the equipment mounting base 6 is a movable equipment mounting base made of a steel plate.

[0084] Furthermore, the equipment installation base 6 is a rectangular plate or a square plate formed by welding steel plates, and at least two groups of lifting ears 7 are symmetrically welded on at least one group of opposite sides of the equipment installation base 6.

[0085] Furthermore, the low-voltage DC gear fuel pump includes a low-voltage DC motor 1 and a gear fuel pump 2 connected via a coupling 9 .

[0086] Furthermore, a U-shaped shield is installed outside the coupling 9.

[0087] Furthermore, two equipment mounting bosses 8 are installed on the equipment mounting base 6, and a low-voltage DC gear fuel pump is installed on each equipment mounting boss 8. The position of the equipment mounting boss 8 is set according to the installation requirements of the low-voltage DC gear fuel pump in the equipment filling space.

[0088] Furthermore, the equipment mounting base 6 is connected to the equipment mounting boss 8 by welding.

[0089] Furthermore, the equipment mounting boss 8 is connected to the threaded bolts of the low-pressure DC gear fuel pump.

[0090] Furthermore, an internal threaded mounting hole is provided on the mounting panel of the equipment mounting boss 8, and the mounting through hole on the base of the low-pressure DC gear fuel pump is fixedly connected with the internal threaded mounting hole through bolts, and the low-pressure DC gear fuel pump is installed on the mounting panel through the fixed connection.

[0091] Furthermore, the plurality of low-pressure DC gear fuel pumps are arranged in parallel via a fuel pipeline, and the bottom of the fuel pipeline is connected to the equipment mounting base 6 via a bracket.

[0092] Furthermore, the fuel pipeline includes an inlet pipe, an outlet pipe, an inlet multi-way pipe, and an outlet multi-way pipe, and the inlet multi-way pipe and the outlet multi-way pipe are provided with three branch pipes matching the number of low-pressure DC gear fuel pumps; the inlet pipe is connected to a branch pipe of the inlet multi-way pipe, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe; each of the other two branch pipes of the inlet multi-way pipe is connected to the pump inlet of a low-pressure DC gear fuel pump; each of the other branch pipes of the outlet multi-way pipe is connected to the pump outlet of a low-pressure DC gear fuel pump.

[0093] Furthermore, a stop valve 4 is provided at the pump inlet of each gear fuel pump 2, and a check valve 3 is provided at the pump outlet of each gear fuel pump 2; among the other branch pipes of the inlet multi-way pipe, each branch pipe is connected to the stop valve 4 of a low-pressure DC gear fuel pump; among the other branch pipes of the outlet multi-way pipe, each branch pipe is connected to the check valve 3 of a low-pressure DC gear fuel pump.

[0094] Furthermore, the pipes of the fuel line are connected to each other through flanges, the pipes of the fuel line and the valves are connected to each other through flanges, and the pipes of the fuel line and the gear fuel pump 2 are connected to each other through flanges.

[0095] Furthermore, the inlet pipe is connected to a branch pipe of the inlet multi-way pipe through an inlet flange 5-A, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe through an outlet flange 5-B.

[0096] Example 2

[0097] A method for nuclear grade identification of a low-voltage DC gear fuel pump unit comprises the following steps:

[0098] 1. Gear fuel pump unit performance test;

[0099] 2. Low voltage DC motor performance test;

[0100] 3. Assemble low-voltage DC gear fuel pump;

[0101] 4. Low-voltage DC gear fuel pump performance test;

[0102] 5. Assemble the low-voltage DC fuel pump unit;

[0103] 6. Low-voltage DC fuel pump unit performance test;

[0104] Furthermore, before step 1, the method further includes the following steps: initial inspection of the low-voltage DC motor and the gear fuel pump assembly.

[0105] Further, step 1 includes the following steps: adjusting the outlet pressure of the gear fuel pump group through the outlet check valve 3 of the gear fuel pump 2, measuring the head, flow rate, shaft power and speed value of the gear fuel pump 2 at more than 6 different discharge pressure operating points including a zero pressure point and a rated discharge pressure point according to the requirements of JB / T6434 B-level accuracy, and drawing a PQ curve;

[0106] By adjusting the opening of the check valve 3 at the outlet of the gear fuel pump 2, the outlet pressure of the gear fuel pump group reaches the rated value, and the current of the low-voltage DC motor is measured;

[0107] By adjusting the opening of the check valve 3 at the outlet of the gear fuel pump 2, the outlet flow of the gear fuel pump group reaches the rated value, and the current of the low-voltage DC motor is measured;

[0108] Under the input power supply voltage limit condition of -15%, measure the flow rate of the gear fuel pump group at rated pressure;

[0109] Under the input power supply voltage limit condition of +10%, measure the flow rate of the gear fuel pump group at rated pressure.

[0110] Furthermore, in step 2, the low voltage DC motor performance test includes the following steps: a low voltage DC motor benchmark performance test, a low voltage DC motor thermal aging test, a low voltage DC motor vibration aging test, and a low voltage DC motor electrical stress aging test.

[0111] Furthermore, the low-voltage DC motor benchmark performance test includes the following steps: pre-test detection of the low-voltage DC motor benchmark performance test, measurement of the insulation resistance of the winding to the low-voltage DC motor casing and between the windings in cold and hot states, low-voltage DC motor load test, low-voltage DC motor withstand voltage test, and inspection and analysis of the low-voltage DC motor.

[0112] The low-voltage DC motor is subjected to low-voltage DC motor thermal aging test, low-voltage DC motor vibration aging test and low-voltage DC motor electrical stress aging test according to the requirements of IEEE 334-1994 standard. In the low-voltage DC motor thermal aging test, the thermal aging temperature is 220℃ and the aging time is 596 hours. In the low-voltage DC motor vibration aging test, an acceleration of 1.5g is used to vibrate the DC motor for 1 hour. In the low-voltage DC motor electrical stress aging test, a voltage of 2 times the rated voltage plus 2 / 3 of 1000V is applied for 1 minute.

[0113] The nuclear-grade DC fuel pump group of the emergency diesel generator has significant thermal aging, mechanical stress aging and electrical stress aging mechanisms, and earthquake is the only design basis event. Further, in step 6, the low-voltage DC fuel pump unit test includes the following steps: low-voltage DC gear fuel pump unit benchmark performance test, low-voltage DC gear fuel pump unit seismic test, and low-voltage DC gear fuel pump unit benchmark performance test after seismic test.

[0114] Furthermore, the benchmark performance test of the low-voltage DC gear fuel pump unit includes the following steps: measuring the insulation resistance of the winding to the DC motor housing and between the windings in cold and hot states, load testing of the low-voltage DC gear fuel pump unit, withstand voltage testing of the low-voltage DC gear fuel pump unit, and inspection and analysis of the low-voltage DC gear fuel pump unit.

[0115] Furthermore, the seismic test of the low-voltage DC gear fuel pump unit includes the following steps: an exploration test before the seismic test of the low-voltage DC gear fuel pump unit, a seismic test of the low-voltage DC gear fuel pump unit, an inspection during the seismic process of the low-voltage DC gear fuel pump unit, and an inspection after the seismic process of the low-voltage DC gear fuel pump unit.

[0116] During the seismic test of the low-voltage DC gear fuel pump unit, the low-voltage DC gear fuel pump unit shall be subjected to 5 consecutive OBE vibrations to simulate the cumulative effect of earthquake fatigue. After the 5 OBE tests, the low-voltage DC gear fuel pump unit shall be subjected to one SSE vibration.

[0117] The low-voltage DC gear fuel pump unit of Example 1 was subjected to nuclear grade certification using the nuclear grade certification method. The low-voltage DC gear fuel pump unit of the present invention ensured structural integrity and safety function operability at all stages of the certification.

[0118] Example 3

[0119] The low-pressure DC gear fuel pump unit of Example 1 is nuclear grade certified according to the following standards:

[0120] IEEE 323-2003, IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power Generating Stations.

[0121] IEEE 334-1994, IEEE Standard for Qualifying Continuous Duty Class 1E Motors for Nuclear Power Generating Stations.

[0122] IEEE 344-208, IEEE Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations.

[0123] GB / T 8625-1992, Seismic evaluation of electrical equipment for safety systems in nuclear power plants.

[0124] The low-voltage DC gear fuel pump unit of Example 1 meets the nuclear safety requirements of the above standards and also meets the technical specifications of nuclear-grade emergency diesel engines.

[0125] The low-voltage DC gear fuel pump and low-voltage DC motor 1 of Example 1 have passed the appraisal of nuclear-grade low-voltage DC gear fuel pump and 1E-grade DC motor respectively, and the appraisal results are qualified and meet the nuclear safety requirements. At the same time, the equipment reliability of the emergency diesel engine is improved, and the depth defense capability of the nuclear power plant is guaranteed.

[0126] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A low-pressure DC gear fuel pump unit that has passed nuclear grade certification, characterized in that: It comprises an equipment mounting base and a low-voltage DC gear fuel pump mounted on the equipment mounting base (6), wherein a plurality of low-voltage DC gear fuel pumps are arranged in parallel; The equipment installation base (6) is a movable equipment installation base made of a steel plate; The low-voltage DC gear fuel pump comprises a low-voltage DC motor (1) and a gear fuel pump (2) connected via a coupling (9); The electromagnetic parameters of the low-voltage DC motor (1) are designed according to the torque characteristics of the gear fuel pump (2), and a small number of series-connected shunt motors are used; A plurality of equipment mounting bosses (8) are mounted on the equipment mounting base (6), each equipment mounting boss (8) is mounted with a low-voltage DC gear fuel pump, and the position of the equipment mounting boss (8) is set according to the installation requirements of the low-voltage DC gear fuel pump in the equipment loading space; A plurality of low-pressure DC gear fuel pumps are arranged in parallel through a fuel pipeline, and the bottom of the fuel pipeline is connected to the equipment mounting base (6) through a bracket; The fuel pipeline includes an inlet pipe, an outlet pipe, an inlet multi-way pipe, and an outlet multi-way pipe. The inlet multi-way pipe and the outlet multi-way pipe are provided with a plurality of branch pipes matching the number of low-pressure DC gear fuel pumps; the inlet pipe is connected to a branch pipe of the inlet multi-way pipe, and the outlet pipe is connected to a branch pipe of the outlet multi-way pipe; each of the other branch pipes of the inlet multi-way pipe is connected to a pump inlet of a low-pressure DC gear fuel pump; each of the other branch pipes of the outlet multi-way pipe is connected to a pump outlet of a low-pressure DC gear fuel pump.

2. The low-pressure DC gear fuel pump unit that has passed the nuclear grade certification according to claim 1 is characterized in that: A stop valve (4) is provided at the pump inlet of each low-pressure DC gear fuel pump, and a check valve (3) is provided at the pump outlet of each low-pressure DC gear fuel pump; each branch pipeline of the other branch pipelines of the inlet multi-way pipeline is connected to the stop valve (4) of a low-pressure DC gear fuel pump; each branch pipeline of the other branch pipelines of the outlet multi-way pipeline is connected to the check valve (3) of a low-pressure DC gear fuel pump.

3. The low-pressure DC gear fuel pump unit that has passed nuclear grade certification according to claim 1 is characterized in that: The pipes of the fuel line are connected to each other through flanges, the pipes of the fuel line and the valve are connected to each other through flanges, and the pipes of the fuel line and the gear fuel pump (2) are connected to each other through flanges.

4. The method for nuclear grade identification of a low-voltage DC gear fuel pump unit that passes nuclear grade identification according to any one of claims 1 to 3, characterized in that: The steps include: (1) Performance test of gear fuel pump assembly; (2) Performance test of low-voltage DC motor; (3) Assembly of low-voltage DC gear fuel pump; (4) Performance test of low-voltage DC gear fuel pump; (5) Assembly of low-voltage DC fuel pump unit; (6) Performance test of low-voltage DC fuel pump unit.

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