In the styrene distillation system, in order to effectively avoid the self-polymerization of styrene, to reduce the formation of polymers, you must add high sulfur-free polymerization inhibitor in the system NSI inhibitor NSI through the diaphragm metering pump delivery to the styrene separation tower resistance Polymerization agent NSI is toxic and hazardous material, so the diaphragm pump is installed in a semi-enclosed square pool. Poor ventilation in the pool, the pipeline near the pump more maintenance space is small, so regulate the diaphragm pump repair method is conducive to improving maintenance efficiency. 1 The basic structure and working principle The diaphragm metering pump described in this article by the drive system, crankcase, hydraulic system and pump head composed of four parts. Membrane metering pump work, the motor driven worm gear crankshaft rotation, the crankshaft through the connecting rod will be converted to rotary movement of the reciprocating motion of the plunger, plunger movement hydraulic oil in the hydraulic chamber to transmit the force acting on the inside and outside the diaphragm, The reciprocating motion of the inner diaphragm and the outer diaphragm changes the volume of the medium chamber. At the same time, the media is sucked in from the inlet of the pump head and discharged from the outlet through the control of the inlet and outlet check valves. When the need to change the flow of the pump, rotate the manual adjustment wheel, by changing the eccentricity of the crankshaft system to control the size of the plunger stroke, the hydraulic cavity force changes, thereby changing the diaphragm reciprocating range, to achieve flow regulation. Casing&tubing pipe OCTG Linzhou Fengbao Pipe Industry Co.,Ltd. , https://www.cfbpcoltd.com
2 Failure Analysis and Processing 2.1 The pump is not on the amount or on the amount of inadequate causes and treatment (1) diaphragm failure or check valve clogging If the pump is not on the amount or on the amount of insufficient, we must first check whether the check valve is clogged Or the outer diaphragm fails. Check the first pump head check valve body, start the motor, and adjust the plunger stroke to observe whether the change in the amplitude of the diaphragm, if the diaphragm with plunger stroke size and change the range of motion, then the diaphragm intact . Then the water into the check valve, if the water can not enter from the entrance, or can not flow from the outlet, then the check valve has been blocked, you need to clean; if the water can flow from the outlet, the inlet outflow, Need to adjust. It is quite common to have a check valve clogged because there is too much impurity during the NSI compounding process. The solution is to change the pump inlet pipe from the tank bottom to the tank wall and raise the height of the pipeline to allow impurities to settle at the bottom of the tank and drain it regularly.
Grade: J55~N80,L80,R95,P110~Q125,etc.
O.D: 1.660"~13-3/8"
End type: Thread/EUE
Diaphragm metering pump troubleshooting
(2) attached to the tank inlet check valve damage
When the pump is working, the hydraulic chamber is filled with hydraulic oil. When the hydraulic oil in the chamber is insufficient, the hydraulic oil in the oil tank will fill the gap through the inlet valve. If the valve is damaged, the diaphragm will stop moving or the operating range is not enough, which will cause the pump not to be on or insufficient . Attached oil tank inlet check valve failure reasons are generally three kinds: (1) the spool and the valve seat is not good; (2) valve sealing ring failure; (3) valve spring failure or its pre-tightening force is not appropriate.
The solution is: exchange the appropriate parts; in the third reason, improper preload to be adjusted, the spring seat structure shown in Figure l. When adjusting, loosen the upper stem nut (663A), the spring plate (660) and the spring (662). Start the motor, the hydraulic fluid in the hydraulic chamber should be able to overflow the inlet valve as the plunger moves and the valve stem (661) moves. Then gradually tighten the nut on the stem to increase the spring load until the stem stops moving up and down, then loosen the stem nut and then press the stem to drain the residual air in the hydraulic chamber. Finally fill the oil sump with oil and install the oil sump cover. (3) Failure of the cylinder wall sealing ring After the failure of the cylinder wall sealing ring (652) and the sealing ring (23), the hydraulic oil in the hydraulic chamber will leak into the crankcase 2),
Cause insufficient pump flow. (4) Safety relief valve set value is too low When the safety relief valve set value is lower than the pump outlet pressure, it will make the hydraulic chamber and attached to the hydraulic tank short circuit between the circulation, will also cause the pump outlet flow is insufficient Or not on the pump, then to reset the pressure relief valve. (5) gearbox failure When the worm gear mechanism is damaged, the crankshaft system will be paralyzed, causing the pump to stop and pump not on the amount.
2.2 Pump flow regulation is not allowed or can not be adjusted Pump flow regulation is not allowed or can not be adjusted mainly due to stroke adjustment agencies (see Figure 3) failure caused the failure occurred due to the following:
(1) Loosening the fastening screw (521) dislocates the hand wheel (516), causing the locking part (522) to be locked and failing, resulting in a discrepancy in the stroke adjustment. Approach: reset each loose pieces.
(2) Loosen fastening screw (704E), resulting in loose adjustment of adjustment screw (524) and adjustment of stroke. Approach: Tighten the fastening screws.
(3) The locking screw (704D) is loosened so that the pointer (351) moves away from the seat, resulting in a discrepancy in the travel adjustment. Remedy: Tighten the locking screw after resetting the pointer.
(4) Adjustment of internal thread (526) and adjustment screw (524) thread wear or slippage, causing adjustment is not allowed. Approach: repair damaged internal thread, finishing or replacement of adjusting screw.
(5) pump shaft and drive bushing due to wear and tear caused by the gap becomes larger, resulting in regulation is not allowed Treatment: Replace the bushing.
2.3 safety relief valve adjustment Safety relief valve (see Figure 4) can ensure that the hydraulic chamber constant hydraulic pressure, which play a protective role. If the safety relief valve pressure relief set value is too large, diaphragm and cylinder seal ring will cause damage, thus affecting the life of the pump; setting too small will cause the pump is not on the amount or pump insufficient, therefore, it must Working at rated value. Adjustment steps are as follows:
(1) to the pump body fitted with an outlet valve, a pressure gauge after the refill valve, pressure gauge scale 30 should be higher than the set value.
(2) Unscrew the wide cover (739), loosen the tightening screw (663A) and loosen the tightening bolt (738) for two turns.
(3) Disassemble the oil tank cover, start the pump and check the outlet of the relief valve. At this moment, the hydraulic oil should flow from the hydraulic chamber through the relief valve to the oil sump. The pressure gauge at the outlet of the pump reads "0" or minimum.
(4) Tighten bolt (738) slowly until pressure gauge indicates set pressure (0.623MPa). Tighten the nut (663A) and install the bonnet and oil reservoir cover.