7 replies to this topic

[Valeriacortez11]

Good evening everyone.
What an excellent platform, I come to you because I need a professional opinion.
I am an engineering student, I have a project to size a steam accumulator for an industry.
I have searched a lot of literature and I have found that for these conditions a 38m3 accumulator is adequate:

I put them in context.
The 10,000 kg/h boiler is currently working at 7.5 to 8 bar (173C approx), and this steam enters the distribution manifold where it is regulated so that the superheated steam becomes saturated at 6.5 bar.

As a textile industry has a peak demand of up to 16,000 kg/h, I have been recommended to size based on the capacity of the boiler (assuming that the accumulator should give me 10,000 kg/h)
and not the peaks (spirax saico is based on peak demand).

I know that for the accumulator to work I must generate a pressure difference so I have designed the boiler to operate at 10 bar g, that would be the inlet pressure of the accumulator and that this operates at 8 bar, design pressure of the accumulator and saturated steam out at 7 bar so that when connected to pipes (still not clear to me) is regulated to the pressure needed in the plant with textile processes.

The above mentioned gives me an accumulator of 38m3. I do not work in the steam industry or anything, so I need someone to tell me if this value seems logical or exaggerated.

I also need advice if I have misdiagnosed the accumulator.

[shvet1]

I am an engineering student, I have a project 

 

1. Please be sure to post to the correct forums. Students should post in the student forum, while professionals should use the Industrial Professional and other forums.

https://www.cheresou...ting-questions/

[breizh]

Hi,

I guess this is the link you are refereeing to:

https://www.spiraxsa...ors#article-top

Why don't you call or drop an email to Spirax?

Edit :

Discussion on the topic from another website where you can find a reference for such calculation

:Handbook of Mechanical Engineering Calculations by Tyler Hicks -section 8-100

 

https://www.eng-tips...d.cfm?qid=14016

 

 

Breizh 

[katmar]

The purpose of an accumulator is to match the variable demand of the plant to the steady supply from the boiler. This allows the plant to draw steam at a higher instantaneous rate than the boiler can deliver, but these peaks have to be offset by dips in demand that make the average demand less than the average supply. This is why Spirax Sarco base their design on the peaks. Spirax Sarco have been around pretty much since steam was invented and they know what they are doing.

The only design parameter for the accumulator that would be based on the boiler capacity is the steam inlet flow.

So until you have details on the flow rates and durations of the peaks and valleys you can't do much in terms of designing the accumulator.

[Valeriacortez11]

El propósito de un acumulador es hacer coincidir la demanda variable de la planta con el suministro constante de la caldera. Esto permite que la planta extraiga vapor a una velocidad instantánea mayor que la que la caldera puede entregar, pero estos picos deben compensarse con caídas en la demanda que hacen que la demanda promedio sea menor que el suministro promedio. Por eso Spirax Sarco basa su diseño en las cimas. Spirax Sarco existe prácticamente desde que se inventó el vapor y saben lo que están haciendo.

El único parámetro de diseño para el acumulador que se basaría en la capacidad de la caldera es el flujo de entrada de vapor.

Entonces, hasta que no tenga detalles sobre los caudales y las duraciones de los picos y valles, no podrá hacer mucho en términos de diseño del acumulador.

 

Thank you very much for answering me, you're right, I have that problem because it is a textile industry, it seems that they do not have a good operation in their consumption therefore, do not know how long it is required that peak consumption, someone told me that some dyers consume 90 min of steam to make the thermoregulation, gives me an accumulator of at least about 100m3 .... In my ignorance, I do not know if it is appropriate to design the accumulator to supply 30% of the steam and the boiler the other 70% to avoid the pressure drop in the boiler when there is an increase in steam production required. 

 

Maybe you can give me an opinion, thank you. 

Edited by Valeriacortez11, 21 April 2024 - 04:26 PM.

[Valeriacortez11]

Hi,

I guess this is the link you are refereeing to:

https://www.spiraxsa...ors#article-top

Why don't you call or drop an email to Spirax?

Edit :

Discussion on the topic from another website where you can find a reference for such calculation

:Handbook of Mechanical Engineering Calculations by Tyler Hicks -section 8-100

 

https://www.eng-tips...d.cfm?qid=14016

 

 

Breizh 

 

Thank you Breizh. 

It has helped me a lot, I feel more confident with the calculations. 

Now I only have the difficulty of how to integrate the accumulator to the plant, to show that it will result in energy savings.

[katmar]

During the peaks in demand you can rely on the normal steam rate coming from the boiler as well. During this time the accumulator will not accumulate any steam, but it just becomes part of the overall balance and you need to design the various elements such that the accumulator can become recharged during the dips in demand from the plant.

Seeing that you are a student and are displaying an admirable desire to learn about the practical aspects of engineering let me make a comment on what is meant by "the boiler's normal steam rate". Boiler specifications will usually give a peak rate and a maximum continuous rate. People usually talk about a boiler using its peak rate but you need to know what it can deliver continuously as well. This will usually be in the 80-85% range of the peak rate.

It is a bit like a motor car. Your car may be able to run at 7000 rpm, but if you drove it at this speed continuously the engine would not last very long. If you back off to 80% of the peak the engine will last many times longer. That is why F1 engines have to be rebuilt so often - they are forced to run at peak performance for a whole race.

 

A note on your reply to Breizh - an accumulator will not give significant energy savings.  The boiler still has to provide all the energy and all the accumulator does is smooth out the load on the boiler so that the boiler does not have to supply the peak demands.  This would hopefully give capital cost savings because the larger boiler would be more expensive than the smaller boiler plus the accumulator. But in my experience accumulators are expensive anyway - although I have been involved in plants where they have been justified and did work well.

Edited by katmar, 22 April 2024 - 02:49 AM.

[breizh]

Hi,

Katmar, as usual, gave a good explanation. 

Accumulator = Buffer. It integrates the variability of the demand (process) and make the boiler running " smoothly". 

Less chaotic = more efficient 

Good luck,

Breizh