My answer was that standard with the VFD pump combination instead of a valve had these advantages:

1. Dramatic reduction in energy costs by eliminating the pressure drop is achieved through the pump;
2. Greater control by eliminating the control valve hysteresis or stickiness;
3. Faster and more responsive flow control valve by eliminating the mechanical action;
4. Elimination of a source of fugitive emissions;
5. Electricity savings from improved power factor of the system.

I have not yet succeeded, these benefits of the VFD anyone actually used this way confirmed.
Barriers

The participants in my survey said the main obstacles to the use of VFD pumps are these:

1. Tradition. “We always use a control valve;
2. The VFD is purchased by a purchaser buys other than the person, the control valves;
3. VFD have a history of unreliable;
4. Our pumps are not designed for use with variable speeds and would be non-linear control use;
5. We have never considered an alternative to a control valve.

The analysis of the benefits

If the energy savings were small, this would be a moot point. However, there are many processes that pumps liquid into the pump to a high head, only to lose that energy, if it appears the pressure drop across a valve, that this source of energy loss up to 25% of that energy to a refinery, chemical or paper mill operation. Even if we designed our processes from the outset with the VFD pumps, we have much smaller electric motors.

There are two factors at work. We know that the flow speed with centrifugal pump speed linear physical laws, which is directly attributable to the perception of non-linearity of paragraph 4. We also know that the electrical current is needed to produce the pump at lower speeds on the main street less than required drive is proportional to the cube of speed ratio. So, by the valve is completely out of the flow path of the amount of stored energy is much larger than one would expect. Of course, less load on the electric motor also means a longer life.

One of the features of the VFD pump combination is the speed of the reaction. Otherwise change the time as the valve in the pressure drop repositioning must stick to the electric motor of the pump to respond within a few cycles of the new spectrum to the new synchronous speed reference work. can react, the speed of the VFD pump to the new current set value so fast that the speed setpoint is ramped necessary to prevent the hammer effect can occur in the process with fluid-filled system when the speed increases.

It is known that the mentioned problem introduced in the tuning of the PID control loops, the variable in the flow loop through the control valve stickiness hysteresis. The valve also leads to a delay caused by mechanical movement of the valve engine. Loops that should be optimized at the factory start-up phase displeased if, the stickiness of the building control valve or the loop to become unstable. In fact, incorporate the latest process control loop auto-tuning software, the actual valve hysteresis compensation up to a point. The loop is detuned gradually, continuing to establish the cause for the process set values ​​for the increased variability due to process upset the flow and pressure control. Today we seem to be that kind of sub-optimal process performance to accept, but we can do better by taking the main source of the error-control valve with a VFD / pump.

The gain from the abolition of the famous fugitive emissions from the packaging of the control valve is clear, if the valve is removed. A less obvious advantage of using a VFD instead of discrete motor starters and electrical switches, operating at a near-linear performance factor. The VFD presents the network as a resistive load with a power factor. When an AC induction motor is placed over the power line, as in a conventional valve position, usually the induction motor is to the power supply with a power factor that can of about 0.7 to 0.9 range range, depending on load and ratings for the engine. This performance means that the amount of electricity consumed by the plant directly to any AC induction motor, the measured power was divided by power connected. In many systems with many of these directly connected three-phase induction motors, which require electric utilities to the use of parasitic capacitances in each phase of the AC cable placed only for the reactive power compensation. Parasitic capacity is required large investments and a constant load on the electrical power plant. Use of VFD eliminates the need for parasitic capacitances because they self-correct for power factor within their own circuits.

What you need to
A wiper seal
Oil pan
One of the candles and jack
engine oil
new oil filter
Changing the oil pump
New oil pan gasket
Keys
Screwdriver
rags or towels

Simple Hydraulic Pump

Step 1 – Prepare the vehicle
First, park your vehicle at the ground level. So be sure to set the parking brake.

Step two – Raise vehicle
Use the jack to lift the vehicle, then it is placed under the car jack so you can safely work under the vehicle.

Step 3 – Engine Oil Drain
Place a plastic container in the sump of the vehicle. Then remove the drain plug and allow oil to flow into the container. Set the engine oil of the old, and remember to put the recycling center after completing the work.

Step 4 – Remove the oil pan
Remove the screws holding the oil pan in place and remove the oil pan of the vehicle. Be careful not to damage the plate to remove them.

Step 5 – Remove the Oil Pump
First, locate the pump oil. On most cars, will be behind the engine. There should have a hose and a filter that are related to a reduction of the sump pump to suck oil. In most cases, there will be only one or two bolts used to hold it in place. Then, remove screws and fix old pump oil aside.

Step 6 – Install the new oil pump
Use the bolt (s) was withdrawn from the old oil pump install the new one. Make sure to apply sufficient torque when tightening bolts.

Step 7 – Install a new pan gasket
Before you can install the new pan gasket, you must delete the old one. Use the scraper to scrape the old gasket. Then, use glue to stick the new gasket on the oil pan gasket. Allow the seal to dry for at least an hour before reinstalling the oil pan.

Step 8 – Replace the drain plug
Tighten the drain plug and tighten the rear.

Step 9 – Replace the oil filter
While you’re under the vehicle, go ahead and replace the oil filter as well. Turn counterclockwise old oil filter and replace it with a new one.

Step 10 – Lower the vehicle
Remove the candles and lower the vehicle.

Step 11-Add new engine Oil
Remove the oil filler cap on top of your car engine and fill the engine with engine oil. Visit the owner’s manual for the number of gallons you’ll need to add.

This is part of the (waste valve) spring a bridge bet. This spring, it is to use another. But there are several ways such as a weight the press itself. ”
This can often leave off the water valve open. Or the ball (ball valve), but the ball valves are made more difficult. Depending on which way we would like.

Recommendations on the oil filter and drain when running in normal condition.

- Work 100 hours for full hydraulic system should make a new filter to clean. Or replaced.

- Change your oil every 3000 or 5000 operating hours.

Rules should be implemented to work

- Do not use cotton or similar material to clean.

- Taking oil from the system. Clean or replace filters and clean the tank should be done with caution and circumspection.

- Add oil to a new system.

- As the machine empty on low pressure or no pressure in it is at least 30 minutes for the oil circulation in all parts of the circuit.

- Set a new all

Monitoring of repeat periodically. During the operation. Especially temperature. Higher temperatures result in faster wear of machinery parts than usual. Check oil level and blockage of the filters frequently than usual. Including the observation volume, which indicates disorders caused or is about to happen.

Stop the machine in a short time if not more than two months do not need to measure anything special. Stop the machine in the long run. Operation should be periodically With the pump walk unarmed without pressure in order to lubricate the best in the regular and Rod should be in a position shrink or a K strip º anti corrosion in case of discontinuation of machinery. that already.

1. Flow. The need for oil.

2. The pressure being used.

3. Size electric motors. Or engine driving the pump.

Suppose to 200 bar maximum pressure cylinder size ID 100 mm. Speed of movement of the cylinder was 3 cm / sec.

A = 10 x 10 x 0.785 = 78.5 cm2.

V = 3 cm / sec.

Q = V x A = 3 cm / sec x 78.5 cm2 = 235.5 cm3 / sec = 14.13 L / min.

Rotate pump drive motor speed 1450 rpm. Therefore, pump size should be 9.7 cc / rev.

Why do hydraulic systems overheat?

Heating of hydraulic fluid in operation is due to inefficiency. The inefficiency of the loss of input power, which is converted into heat. A hydraulic system load thermal energy is equal to the sum of all power lost (PL) by inefficiency and can be expressed as follows:

PLtotal = PLpump + PLvalves + PLplumbing + PLactuators

If the total amount of heat lost power is greater than the heat, the hydraulic system to overheat more. Installed cooling capacity ranges usually between 25 and 40 per cent of electricity consumption, according to the nature of hydraulics.

Temperature of hydraulic fluid
What temperature is too hot? Hydraulic fluid temperatures above 180 ° C (82 ° C) damage to sealants and accelerate oil degradation. During operation of the hydraulic system at temperatures above 180 ° C should be avoided, fluid temperature too high when viscosity is less than the optimum value for the hydraulic system components. This can occur even below 180 ° C as the viscosity of the liquid class.

Maintain stable temperature of fluid
To achieve a stable temperature environment, the ability of a hydraulic system to dissipate heat, must exceed the heat load. For example, a system needs input power of 100 kilowatts continuous and can disperse an efficiency of 80 percent to a heat load of 20 kilowatts. Assuming that the system is designed cooling capacity of 25 kilowatts, all growing, underlining the heat above 25 kilowatts or reduced cooling capacity below 25 kW, the system will lead to overheating.

Consider an example. I was recently asked to investigate and solve an overheating problem in a mobile application. The hydraulic system consists of a motor unit diesel-hydraulic, which is currently used to power a pipe cutting saw. The saw was designed for the under-utilization of the sea and was connected to the hydraulic unit on the surface of a 710-foot cord. The conditions for the operation of the saw were 24 GPM at 3000 PSI.

The hydropower plant has a continuous power of 37 kW and was fitted with a heat exchanger air furnaces. The interchange has been dispersed to 10 kilowatts of heat at room temperature or 27 percent of the available input power (10/37 x 100 = 27) Can. The performance of all components of the cooling system were monitored and their activity within the design.

In this passage, it was clear that the overheating problem was caused by the heat load is excessive. Concerned about the length of the umbilical cord, so I thought the pressure drop. The theoretical pressure drop over 710 feet of pipe ¾ inch pressure is 800 psi at 24 L / min. The pressure drop over the same length of 1-inch return pipe is 200 PSI. The theoretical heat load produced by the pressure drop through the umbilical cord is 1000 PSI (800 + 200 = 1000) was 10.35 kilowatts. This meant that heat stress is the navel of 0.35 kilowatts more than the capacity of heat dissipation of the heat exchanger of the hydraulic system. That’s when they load with the normal heat system (inefficiency caused) in connection with the hydraulic system to overheat.

Beat the Heat

Besides improving chip control and tool life, directing a jet with accuracy at high speed cooling may increase the overall productivity. One of the potential beneficiaries of this approach to liquid cooling is the multitasking turning center. Most of these machines offer the supply of liquid cooling option with a pressure between 70 and 100 bar. In fact, Sandvik Coromant has developed accessories for high pressure coolant specifically for use with such machines, the amount of pressure.

For multitasking machines in particular, inefficient chip removal hinder the ability to make changes effective tools. Sandvik CoroTurn HP system reacts to this riddle. In this system, each tool carrier fitted with two or three nozzles replaceable stainless steel from which coolant is circulated at high pressure. Sandvik said spray heads are mounted near the edge of the temperature in the heat-affected zone (HAZ) below. They are correctly positioned and oriented at an angle, depending on the type of tools and application.

Getting the positioning right is just one of the keys to the effectiveness of this cooling technology delivery. The system pushes the chip and provides localized cooling of the insert point without thermal shock. It does this by producing a precise laminar flow – that is to flow with the energy flows is based on work instead of drawn by turbulence.