Gear Pump Control

Sodium hydroxide or other neutralising agents, water and other solvents if required are normally added to the neutralisation loop using metering pumps. Variable-speed gear pumps controlled by mass-flow meter-based systems can be used. 

After the SO converter has stabilized, the 6—7% SO gas stream can be further diluted with dry air, I, to provide the SO reaction gas at a prescribed concentration, ca 4 vol % for LAB sulfonation and ca 2.5% for alcohol ethoxylate sulfation. The molten sulfur is accurately measured and controlled by mass flow meters. The organic feedstock is also accurately controlled by mass flow meters and a variable speed-driven gear pump. The high velocity SO reaction gas and organic feedstock are introduced into the top of the sulfonation reactor,, in cocurrent downward flow where the reaction product and gas are separated in a cyclone separator, K, then pumped to a cooler, L, and circulated back into a quench cooling reservoir at the base of the reactor, unique to Chemithon concentric reactor systems. The gas stream from the cyclone separator, M, is sent to an electrostatic precipitator (ESP), N, which removes entrained acidic organics, and then sent to the packed tower, H, where SO2 and any SO traces are adsorbed in a dilute NaOH solution and finally vented, O. Even a 99% conversion of SO2 to SO contributes ca 500 ppm SO2 to the effluent gas. 

Since discrete quantities are trapped and transferred, the delivery pressure and flow varies, as shown in Figure 32.21, which also illustrates how increasing the number of cylinders in a reciprocating pump reduces fluctuations. In the case of lobe and gear pumps the fluctuations are minimized by speed of rotation and increasing tooth number, but where, for control or process reasons, the ripple in pressure is still excessive, means of damping pulsations has to be fitted. Often a damper to cope with this and pressure pulses due to valve closure is fitted, and two types are shown in Figure 32.22. 

In air conditioning circles, the tower normally represents the final heat sink in a turnkey package which would include compressors/condensers, pipework, ducting, fans, pumps, control gear, etc. Where consultants and experienced contractors are concerned, the tower specification is well defined and the purchases based upon economics related to efficiency. 

The mass flow of organic feedstock to the film reactor is detected and adjusted by a mass flow meter, which automatically controls the speed of the gear pump feeding the organic to the reactor. 

Figure 12.5 An extrusion process with a downstream gear pump with the screw operating in inlet pressure control and followed by the screw in manual operation (constant screw speed). The large level of variation in the motor current during constant screw speed control suggests that the extruder process is unstable, and the control algorithm is not the root cause for the variation in the motor current...

Figure 12.6 Pressure at the inlet to the gear pump for the data presented in Fig. 12.5. The pressure increased during manual control because the flow rate of the extruder was slightly higher than the rate of the pump...

The objective of this test was to assess the wax deposition tendency of Troll crude in a cool subsea flowline. The equipment consists of a thermostatted stirred vessel from which crude oil is circulated by a gear pump through a thermostatically controlled stainless steel capillary. Tne temperature in the vessel was maintained at 6S°C and the capillary tube was held at a constant temperature below the cloud point. 

The pump consists of dual reciprocating pistons which are hydraulically controlled. Oil is distributed by the system to the two pistons which are 180° out of phase (as with the Altex and Waters systems). A fixed volume of hydraulic fluid is delivered to the control system for every revolution of a special gear pump. The latter is controlled by a motor having a constant speed and a tachometer feedback circuit. Other compensating circuits... 

Water Metering Pump Gear Pump + DC Control 3 2.5... 

To form a pendant drop, the gear pump (2) was switched off and the air driven oscillating double piston pump (4) with 1.8 ml per stroke was used. This pump has the advantage of keeping the volume constant in the apparatus while pumping. The drop size was controlled by closing the metering valve (5). 

A screen changer is located between the extruder and die to remove any dirt or foreign particles. Gear pumps located between the extruder and die reduce power consumption and provide a more uniform rate of polymer delivery to the die, providing improved gauge control [3]. 

The contents of the addition tank (5 gal) is recirculated by a small gear pump at 1.5 gpm to maintain the suspension. To achieve the proper addition rate, the three-way valve forwards solution to the reactor about 2% of the time (0.0333 x 100/1.5 = 2.222). Therefore, the timer directs the valve forward for about 2 s and recirculates the solution for about 98 s. Based on observed weight loss in the weigh tank, minor adjustments are made to the timer by either a process controller or an operator. 

In recent years, the addition of tallow has moved directly to dairy and beef feed lots. Small, heated, insulated tanks have been developed to receive and hold fat shipments (Figure 7). As described earlier, beef tallow is the most compatible fat for ruminants. It may be sprayed or flowed, at 2-3% of dry matter onto rations of chopped hay, other roughages, grains, or concentrates while in the mixer, or top-dressed on hay or other forages. Feed mixing operations like these require a positive displacement pump, like a Moyno or gear pump with variable-speed drive set to deliver a known amount of fat within a specific time period. As an alternative, mixers in feed mills can be mounted on load cells and equipped with controllers to stop the flow of fat when the desired weight has been added. 

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