Start-up of FELUWA Double-Tube Diaphragm Pump

At Silkem company, zeolite was pumped to the spray dryer using a screw pump. Because the pump operates almost every day of the year and due to the material it pumps, the stator and rotor consequently wear out quickly, which causes high maintenance costs on an annual basis. In order for the diaphragm pump to operate, they determined that an inlet pressure of the liquid (zeolite ZP-4A) of 2 to 2.5 bar was required. They then replaced the centrifugal pump with the previously used screw pump, which easily achieves the desired pressure of 2.5 bar.

Problem

At Silkem company, zeolite was pumped to the spray dryer using a screw pump. Because the pump operates almost every day of the year and due to the material it pumps, the stator and rotor consequently wear out quickly, which causes high maintenance costs on an annual basis. Therefore, at Silkem company they were looking for a better alternative that would reduce maintenance costs on an annual basis.

When searching for a better alternative, they came across the diaphragm pump SG 130 – 2 DS17 and, based on the presentation of this pump through videos and specifications, decided to purchase it. When they replaced the screw pump that had been in use until then with the diaphragm pump SG 130 – 2 DS17, numerous problems arose. The first major problem was that the diaphragm pump would not pump the material to the spray dryer.

After various attempts, they determined that the inlet pressure to the diaphragm pump SG 130 – 2 DS17 was too low, so they installed a centrifugal pump in front of it. The centrifugal pump, with the material pumped at Silkem, d. o. o., achieves a maximum pressure of 1 bar, which is insufficient for the operation of the diaphragm pump SG 130 – 2 DS17.

Results

In order for the diaphragm pump to operate, they determined that an inlet pressure of the liquid (zeolite ZP-4A) of 2 to 2.5 bar was required. They then replaced the centrifugal pump with the previously used screw pump, which easily achieves the desired pressure of 2.5 bar. Because the diaphragm pump SG 130 – 2 DS17 did not pump the desired liquid zeolite ZP-4A even at an inlet pressure of 2 to 2.5 bar.

They abandoned the start-up of the diaphragm pump SG 130 – 2 DS17. Therefore, focus was placed on the problem of why the diaphragm pump does not pump the liquid. After searching through various literature, it was determined that zeolite has thixotropic properties, which means that when at rest it has very high viscosity, but if the mixture is stirred, it transforms into a mixture of lower viscosity.

Due to the high viscosity that zeolite has, it was determined that the diaphragm pump is not suitable for pumping zeolite ZP-4A, as the liquid flows more slowly and is sticky. It was also determined that the liquid zeolite ZP-4A settles quickly and consequently sediment forms in a short time, which is very poor, considering the principle on which the diaphragm pump SG 130 – 2 DS17 operates. It was also determined that the diaphragm pump has a pulsation dampener installed, which would dampen the flow fluctuation, which is not good, as there would be different injection through the nozzles on the spray dryer (sometimes more, sometimes less), which would not be acceptable, as the injection at the nozzles in the spray dryer must always be the same.