What are the safety operation procedures for roots blower during trial operation?

There are safety risks such as mechanical operation, pressure fluctuation and electrical operation in the trial operation stage of Roots blower, so the safety operation procedures must be strictly followed to ensure the safety of equipment, personnel and production system. The following are the key safety operation procedures for trial operation, covering the whole process of preliminary preparation, operation monitoring and emergency treatment:

I. Before commissioning: Safety preparation and inspection (core premise)

Before the trial operation, it is necessary to thoroughly investigate the potential safety hazards of "man, machine, material, law and environment", and it is strictly forbidden to start the equipment when the preparation is not sufficient.

Personnel qualification and protection preparation

Operators must receive special training and be familiar with equipment structures (such as rotors, bearings and safety valves), operating procedures and emergency handling procedures. Unlicensed personnel are prohibited from operating.

Wear a full set of personal protective equipment (PPE): safety helmet, impact goggles, noise-proof earplugs (roots blower running noise is usually ≥85dB, which should meet the requirements of GB/T 23466), non-slip labor protection shoes, and wear anti-scalding gloves when contacting high-temperature components (such as bearings, import and export pipelines).

Equipment and system safety inspection

Mechanical structure safety:

Check whether the connecting bolts of the fan casing and inlet and outlet pipes are fastened to avoid the parts from loosening and falling off due to vibration during operation; Protective covers (such as couplings and belt pulley protective covers) must be completely installed, without damage or displacement, so as to prevent from being involved in injuries.

Manually move the rotor (in the power-off state), and make sure that the rotor rotates flexibly, and there is no jamming and abnormal friction, so as to avoid motor overload or mechanical damage caused by rotor jamming during trial operation.

Electrical safety:

Check whether the power line and control line are connected in a standard way, and the grounding (PE) resistance is less than or equal to 4Ω (it needs to be detected by a grounding resistance tester) to avoid electric leakage and electric shock; The motor junction box and control cabinet are well sealed, without water and dust accumulation.

Test whether the emergency stop button, overload protection (such as thermal relay) and short circuit protection (such as air switch) are sensitive and effective: when the emergency stop button is pressed, the equipment needs to be powered off immediately; When simulating overload, the protection device should trigger power failure.

Process system safety:

The inlet and outlet pipelines shall be equipped with safety valves (the take-off pressure is 1.1-1.2 times of the rated pressure, which has been verified to be qualified) and pressure gauges (the range covers 1.5 times of the rated pressure, and the accuracy is ≥1.6) to ensure that the pressure can be automatically released when the pressure exceeds the limit, so as to avoid the pipeline bursting.

Check whether there is blockage in the system (such as filter blockage and pipeline valve closing). Before commissioning, it is necessary to open the inlet and outlet valves (or adjust the opening according to the process requirements). It is forbidden to "run the tank in a stuffy way" (when there is no exhaust passage, the sudden pressure rise in the machine will easily lead to rotor deformation and shell cracking).

Environmental safety:

Warning signs should be set in the trial operation area (such as "Equipment trial operation, non-operating personnel are forbidden to enter"), irrelevant sundries should be cleared, and an operation channel of at least 1.5m should be reserved.

If the fan transports flammable and explosive gases (such as biogas), it is necessary to detect the gas concentration in the area (10% or less of the lower explosion limit), and it is forbidden to open fire and electric sparks, and it is well ventilated; When transporting toxic gases, gas masks and gas detectors are required.

Second, in trial operation: safe operation and monitoring (key link)

Trial operation shall be carried out in stages (no-load → low load → rated load), and the equipment status shall be monitored throughout, and illegal operation is strictly prohibited.

Safe operation in start-up stage

Confirm again before starting: the inlet and outlet valves are in the correct opening (during no-load trial operation, the outlet valve can be fully opened and the inlet valve can be opened by 50%-80%; Adjust according to process requirements when loaded), the lubricating oil level is between the "highest-lowest" scale of the oil standard (no leakage, no emulsification), and the electrical wiring is not loose.

Use the "inching start" test: cut off the power immediately after pressing the start button, and observe whether the motor rotation direction is consistent with the direction marked by the fan (reverse rotation will lead to rotor collision and abnormal pressure). If the rotation direction is wrong, it is necessary to adjust the motor wiring phase sequence and re-test.

During the formal start-up, the operator should stand on the side of the equipment (away from the coupling, inlet and outlet pipeline interfaces and other risk points) to observe whether the start-up process of the equipment is stable, and there is no violent vibration or abnormal noise (such as metal rubbing sound and sharp abnormal sound). If there is any abnormality, press the emergency stop button immediately.

Safety monitoring in operation stage

Parameter monitoring (recorded once every 15-30 minutes):

Measures for handling abnormal safety standards of monitoring projects

Open the pressure relief valve when the outlet pressure does not exceed 1.05 times the rated pressure, and check whether the pipeline is blocked.

Stop the motor when the current does not exceed 1.1 times the rated current, and check whether the motor is overloaded or mechanically stuck.

When the bearing temperature is ≤80℃ for rolling bearing and ≤ 70℃ for sliding bearing, stop the machine and check the lubricating oil quantity/model or bearing wear.

Check the cooling system (such as cooling fan and cooling water pipe) when the lubricating oil temperature is usually ≤60℃ (refer to the equipment manual for details).

Vibration value When the vibration speed of the bearing seat is ≤6.3mm/s(ISO standard) and the vibration exceeds the standard, stop the machine, and check whether the anchor bolts are fastened and whether the rotor is balanced.

Site safety requirements:

During the trial operation, it is forbidden to remove the protective cover and touch the rotating parts (such as couplings and belts), and it is forbidden to tighten bolts and adjust valves when the equipment is running (it is necessary to stop the machine before operation).

If close inspection is required (such as listening to sound and looking at seal), it is necessary to keep a safe distance (at least 0.5m) to prevent hands and clothes from being involved in the equipment.

Overload operation is strictly prohibited: the low-load trial operation (30%-50% rated load) needs to last for 1-2 hours, and then it is gradually increased to the rated load if there is no abnormality. The residence time in each stage is ≥30 minutes, and it is forbidden to fully load the load at one time.

Handling of abnormal situations (principle of "downtime first")

When the following situations occur, you must immediately press the emergency stop button to stop the machine, and investigate the reasons after the equipment stops completely (the motor does not rotate and the pressure returns to zero):

The equipment makes violent abnormal noise and the vibration amplitude suddenly increases (such as the equipment is displaced due to the loosening of the anchor bolt);

The temperature of bearing and lubricating oil rises sharply (for example, it rises above 15℃ within 10 minutes);

The motor smokes, smells burnt, or the current continuously exceeds the rated value;

Media leakage occurs at the inlet and outlet pipelines and flange interfaces (especially toxic/flammable and explosive media, which need to be cut off before treatment);

After the safety valve jumps, the pressure still cannot drop, or the pressure gauge shows abnormality (for example, the pointer does not move or fluctuates violently).

III. After trial operation: Safe shutdown and closing (necessary steps)

The shutdown operation should be standardized to avoid equipment damage or potential safety hazards caused by improper shutdown.

Safe operation in shutdown stage

Operate in the order of "load reduction → shutdown": firstly, gradually close the inlet valve (or reduce the system load), and press the shutdown button after the outlet pressure drops below 0.1MPa and the motor current drops below 50% of the rated value.

After stopping, it is necessary to observe whether the equipment stops smoothly and there is no "reverse" phenomenon (if the conveying gas is under pressure, the inlet and outlet valves should be closed to prevent the rotor from reversing due to backward flow); After the equipment is completely stationary, turn off the main power supply and cut off the air supply.

Safety work in closing stage

Check the condition of the equipment: clean the sundries on the surface of the fan, check whether there is leakage of lubricating oil, whether the seals (such as shaft seals) are intact, and whether the pipe joints are loose.

Record and handover: sort out the trial operation records (parameters, abnormal conditions and disposal measures) and submit them to technicians for review; If the test run is qualified, the equipment identification plate shall be marked with "Qualified Test Run" and the date; If it is unqualified, it is necessary to hang a "No Start" sign, and try again after maintenance.

Environmental cleaning: clean up the tools and record forms in the trial operation area, recycle the waste materials (if the waste lubricating oil needs to be stored centrally, it is not allowed to be dumped at will), and cancel the warning signs (only after the trial operation is qualified).

IV. Supplementary Safety Requirements for Special Scenes

Explosion-proof roots blower: explosion-proof motor and explosion-proof control cabinet (meeting the regional explosion-proof grade, such as Ex d IIB T4) are required, and non-explosion-proof transformation of all electrical components is strictly prohibited; Non-explosion-proof tools (such as copper tools instead of steel tools to avoid sparks) are prohibited during trial operation.

Trial operation in high-temperature environment (such as outdoor in summer): it is necessary to strengthen the cooling of motors and bearings (such as adding sunshade and forced ventilation), and shorten the parameter monitoring interval (recorded once every 10 minutes) to prevent the equipment from overheating due to high ambient temperature.

Commissioning of linkage system (for example, linkage with dust removal and aeration system): it is necessary to confirm that the signal linkage is normal with the operators of upstream and downstream equipment (for example, when the fan stops, the upstream feed valve will automatically close), so as to avoid sudden pressure rise or media backflow caused by system disharmony.

In a word, the safety core of Roots blower's trial operation is "prevention first, monitoring in place and emergency in time", and it is necessary to run the safety operation procedures throughout the whole process to ensure that each link meets the equipment requirements and national safety production standards (such as GB 50275 Code for Construction and Acceptance of Fan, Compressor and Pump Installation Engineering), so as to avoid equipment failure or personal injury caused by improper operation.