flow control valve

What's the desired end product?

This is carbon black manufacturing industry , the additive along with the feedstock oil goes into the reactor . I tried using control valve (globe type) with .025 Cv =% . But am not able to control the flow. The valve is working almost as if its ON / OFF . The KNO3 solution is pumped from the storage tank into a 2" header line , from there its a 1/2" line and there is a mag flow meter and the control valve . The back pressure of oil into which the additive is to be added at the reactor end varies from 5 Kg to 15.5 Kg depending on the grade of carbon black produced .

well what I think that the temperature of the oil . if it is more higher than boiling point of KNO3 than vapor formed at the downstream may choke the flow in case of control valve at low cv.

for that , metering pumps should function well as there will be no expansion and flow will go direct into the oil .

Hi there,

You will need to give a lot more information if you want a feasable solution.

For the valve - start by looking at the class of shutoff you want. This will determine the valve type. Then look at the process data, viscoscity, compressability, pressure, temperature, flow etc etc and calculate the valve CV, predicted sound levels etc etc etc.

I would then also look at a flow trasnmitter. Here you start with the accuracy class you need. Then look at the process data and this will determine the meter type.

The control side should be staright forward. I would have two flow meters. One measuring the oil flow and one measuring the additive flow. The additive flow will control the valve which controls the amount of additive. I would ratio the additive to the oil flow. Nice and simple.

And because you are measuring flow, your control valve characteristic will most likely be equal percentage. But you would need to look at the process data to be absolutely ceartain.

Again without more information we cannot give you a definate solution. The accuracy of the measurement needed and the class of shutoff are going to determine what solution you take.

Regards,

Craig

There isn't anything wrong with varying the speed and/or the stroke of a dosing pump for those sorts of flowrates, and it may be that the method is the best practicable.

try this.

http://www.yamatake.com/products/bi/iap/ss/cv/SS2-8110-0500.pdf

valve company can give Cv to 0.001 which I feel is sufficent to control the desire flow

Most chemical suppliers will be able to recommend a chemical metering pump to do exacly as you require. Many of these have a pump controller which will accept an analog input which would be from the flow tx of the oil line to vary the injection with the main line flowrate.