steam recovery control

Dears.
Actually, I am recoverying steam in a pressure scrubber from backsteam refiners (wood chips refiners).
Some amount of steam recovered is going to chips heating tank. I am
controlling pressure steam at 3 barg and pressure valve is opening 50-60%, means 3-4 ton/hr of steam is going to atm, rest is going to chips heating tank (2-3 ton/hr is enought to keep 98C).
I want to recover steam which is going to atm, and send it to heat chip washing system. Idea is to keep 3 barg, but adding new line to send rest steam to chip washing system, in order to reduce pressure valve opening close to zero.
I have two alternatives in new line:
1. Put steam flow control (valve and flowmeter). 2. Put steam pressure control (downstream to valve). For example 2 barg.
I dont know what is best solution in order to get good control.
Thanks in advance,
Anibal
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I'm not sure of your control goals here. Are you going to keep the wash water at some constant temperature, or is this a case that you can put whatever steam you make in to the chip wash system? Is there any reason you need to keep it at some pressure? What constitutes good control? Good control of what (and why)?
I can think of several control systems which could be used in this situation, but without a bit on the goals, I don't think it is a good idea to pick one yet.
Michael
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Michael:
I am worry if a install new line of 3 barg recovered steam consumption, I could affect flow of steam to chip heating tank. Because flow of recovered steam is variable.
Then, I need to privilege steam to chip heating tank and all rest or part of rest of steam should go to chip washing system.
In chip washing system, I have temperature tank control. Today, I am using fresh steam which could be replace by recovered steam.
Regards,
Anibal
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Since you have the temperature control for the water in place, just pipe the waste steam from the digerster to the tank, uncontrolled. Right into the water since you can't recover this steam anyway. Maybe add a nozzle to add some velocity at the point of entry.
On 13 Apr 2005 06:31:58 -0700, snipped-for-privacy@inforsa.cmpc.cl (Anibal) wrote:

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Put a check flow valve or at least a vacuum breaker on that steam if you are going to do this. There is nothing quite so embarrassing as explaining how you go chips back in to the steam system. In the event of a shutdown, many steam lines suddenly become fantastic vacuums.
Michael

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I will install a pressure valve control which will be control after principal pressure control, check flow valve and inline inyector steam. Thanks for your comments,
Anibal

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I will put a pressure valve control, check flow valve and inline inyector steam. Thanks for your comments,
Anibal

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The last plant I worked with had a continuous digester, running on pressure control. Any control of waste steam is going to be a slave to the main controller.
If it is desired to just recover the heat, then just route the vent to the water tank feeding the chip washer. Unless the temperature variation in the wash water would be a problem.
If temperature variation is a problem, and it will be, then run the wash water on temperature control just above where it might run by just recovering the vent steam. As the water required more steam, a little more will be drawn from the digester. Keep the temperature control changes small compared to the digester feed, to keep large quantities of raw steam from overcooking the chips.
On 12 Apr 2005 14:23:28 -0700, snipped-for-privacy@inforsa.cmpc.cl (Anibal) wrote:

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