Boiler Drum Water pH and Boiler Feed Water pH

Post the link.

sure

So basically what you are telling us in the link is that the customer's process cooker was either a direct-steam injection, or had a major leak in the cooking jacket? No challenge to dump any condensate from this out of the boiler loop, as you stated. Not only that, there is the USDA requirements for direct contact steam with food products, that clearly states how much neutralizing amine is permitted in such cases.

On a small boiler, the concentrations of neutralizing amine might be really hard to control, especially when said boiler operates in a surge/halt mode of steam delivery.

Perhaps I missed something in your white paper: is most of the steam actually being added to the cheese?

Excellent reply, and you are correct, Steam is being added directly to the cheese.

There were filters on the inject side to supply culinary steam for a direct inject to the product. It has been a while, but I believe it's 2 microns filter for culinary steam. And that would be USDA-3A requirement, (there is a difference between USDA and USDA-3A)..... for some time they were thinking of combining the two, but I believe they are still separate entities.... so to speak.

It was direct steam inject, and the product was contaminating the condensate return with proteins through the steam injectors. The thought was with a higher pressure deferential on the injector side that wouldn't happen, but it does.

And with the boiler sized just enough to do the job in the best of conditions on the heavy loads. I myself believe they were lucky because the actually needs of the steam is not steady, as shown by my graph. I see you came to the same conclusions also.

There really was no reserve. Which was another reason why it would trip. But a larger boiler was out of the question, so we had to address and correct other inefficiencies

Yep. That one is a no-brainer, as to condensate return.

To help with the steam surge, could they make use of a steam buffer vessel? I don't know, and of course it would have to be quite robust as to pressure/temperature stamp. Another small consideration - maybe use something like a clean water supply and a steam eductor operating at higher pressure to arrive at the right steam flow/ heat input to the cheese. That would cut down on interrmittant flow steam requirement.

Yes, the one that design the system should have known better.

The rule of thumb I recall using was was 5 lbs of steam required for every 100 pounds of cheese. to bring the cheese up for 65 degrees F to 150 Degrees F.

And that rule of them was out dated. They are now bring the temps high to the critical point just short of Maillard reaction taking place. And also reducing the amount of moisture. Which increases shelf life by reducing the change of taste of the cheese (sharper)

Just letting it drain by the injectors steam trap was enough. The other steam traps they could return the condensate, but the amount of return was nothing. One thing that was critical, was that the delivery of steam was to be as dry as possible for reasons stated above.

I suppose the direct steam contact method is more efficient in rapid heating. IF the initial steam is present with enough super-heat, the attemperated steam flow (after the water injection) will still be super-heated, and dry.

This is where I meet a lot of impractical engineers.

A large cheese manufacture, I designed and fabricated (2) 750 pound batch cookers.

Operating at 70 lbs of steam (about 315 Degrees F) , with a batch time every 7 minutes approx.?

He wanted to use 150 lbs of steam (about 365 degrees F) thinking the temp/cook time was invertly linear. cutting the batch time down by about a minute. (I'm not going to get into pasteurization)

I told him to try cooking a pizza, or anything that way, then give me a status report of your results.

that is a sound answer, given what you were presented with.

This 64 bar boiler, (~930 psig, 176,370 lb steam/hr, 923 °F), is in range where either all-volatile treatment, or the more protective controlled Na:PO4 ratio (addition of DSP, NaOH (small amount) treatment are both acceptable. I prefer phosphate treatment, (1) additional protection against condenser leaks should they occur, and higher pH, although the free OH^- ion concentration must be kept below 10 mg/L (Pand M alkalinity test), and (2) the quality of the water from the RO plant might not be sufficient to remove all hardness ions, and (3) there is a limit to silica that should enter such boilers, and while a bit higher for your boiler, still best to have higher pH than 8 something to limit silica vaporization into the steam, as the turbine will suffer.

It seems a bit odd that the feedwater pH could be maintained higher than the drum pH, since the make-up water specification is not that great, (in other words, there is still some alkalinity residual in make-up water, along with sodium, etc.)

I think it really remains to be seen how such boilers hold up under such an AVT scheme, but there is long-standing proof of boilers lasting at least 50 years with the alkaline phosphate scheme.

1. HP dosing pump will be used in cases of abnormally high conductivity level

2. Drum water should be more than 9 for safety consideraion , but I stongly recommend you to monitor the OH instead , since this is more reliable reference of alkalinity .

3. Feedwater PH of 9.5 is okey ,to protect pump from abrasion or acidic attack

4. Boiler water TDS pf 30 ppm may not be attainable even with very good boiler water treatment . Two things that may cause lower TDS of your boiler water , it is either you have a very very clean feedwater or the boiler water chemicals are not reacting or functioning .

Sure the operators could achieve 30 ppm TDS in Boiler drum water, even with the make-up to the system being as high as 2 ppm TDS, as long as sufficient continuous blow-down is maintained to control the cycles of concentration (ratio of makeup to blow-down flow) at 15:1 or less. The issue will then be de-aeration of the make-up to a sufficient extent to prevent oxygen attack of economizer tubes, etc.