Help with Molten Salt Solar CSP

[joelsaliman100]

Can anybody help me with questions about CSP using molten salt with a 6000 kilo watt steam turbine generator

[freeztar]

What are your questions?

[joelsaliman100]

I'm not an engineer. I came up with a CSP plant that will run 24 hours a day 7 days a week. After researching on the internet everthing from solar one to sandia there are stil alot of hard facts that need to be worked out.

 

First, will 12,100 pounds of molten salt be enough to generate enough steam to run a 6000 kilo watt steam turbine generator?

[Buffy]

I'm not an engineer. I came up with a CSP plant that will run 24 hours a day 7 days a week...

The being an engineer part can be helpful: first rule is that nothing mechanical will ever run 24/7 without both planned and unplanned down-time...

 

A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible, :)

Buffy

[joelsaliman100]

Of course not. However people say it can only run when the sun is out have already been proven wrong with molten salt Buffy. I have worked in a 10% downtime. But can you help with the real engineering?

 

Like how long will it take 200 hundred arrays generating 20,000 watts each take to heat up 12,100 pounds of salt peter? That is the kind of help I need.

[freeztar]

Saltpeter? I don't think that's the kind of salt you want.

 

200*20kw=4MW

 

So you have a 4MW system. What temp are you trying to heat the salt to?

[joelsaliman100]

Hi Freeztar

 

It is salt peter which is 60% nitrate 40 % something else but commonly refered to as salt peter. The temp is 1050f I have spent about 3 months researching the topic but certain things I cant find. I have seen references to how big the storage tanks, how many gallons of salt and calculators for watts to BTU to calculate heat on liquids which is times 3.413 but not enough to calualte what I need so here I am. I get a lot of funny remarks from people like Buffy but no real help. This is the second science help site I'm at and your are the first person to actually provide a diouloug and I appreciate it. This is actually pretty serious stuff and if my theroy is correct could generate a great business and help convert the US to Solar. There are some great companies out there but I believe that molten salt csp tower is the best.

 

Thanks for your help Freeztar

[JMJones0424]

Most of my interest in solar thermal has been in low temperature storage, so I am not exactly familiar with what you intend to do Joel, but-

 

Saltpeter usually refers to potassium nitrate. The molten salt mixture that I have usually seen referenced is 40% potassium nitrate and 60% sodium nitrate, but this is kept at just over half the temperature that you are aiming for. Are you planning on using gas turbines for electricity generation?

 

I agree that the concept of solar thermal, while no where near as efficient at generation, has high potential in that it can store power generation capability for use at a later time. I wish I could help you further, and I will dig through notes to see if I can find more information, but right now my head is wrapped around a discussion in another thread.

[joelsaliman100]

Here is a link to the govt sandia lab

 

Sandia National Laboratories: Site Title: Page Title I have gotten most of my info there but also others sources.

 

At work will type more tonight.

[COCO1978]

But what exactly you want to do? generate with htf in collectors and indirectly storage with molten salts?

if this is your idea you shoud consider the temperature effect on the htf (much temperature for conventional htfs used in solar): to calculate the amount of salts you need; the first you have to do is to have the entalphy os the salts at diferent temperatures and to know how long will work the system (hours)

 

sorry for my english; i am spanish

[C1ay]

Hi Freeztar

 

It is salt peter which is 60% nitrate 40 % something else but commonly refered to as salt peter. The temp is 1050f I have spent about 3 months researching the topic but certain things I cant find. I have seen references to how big the storage tanks, how many gallons of salt and calculators for watts to BTU to calculate heat on liquids which is times 3.413 but not enough to calualte what I need so here I am. I get a lot of funny remarks from people like Buffy but no real help.

 

No wonder you get funny remarks. You come here with broad, vague questions and no specifics which are required for specific engineering.

 

FYI, the salts most commonly used in such heat storage units are 40% saltpeter (potassium nitrate) and 60% sodium nitrate. It melts at a temperature around 430°F and can be kept in a liquid state at about 550°F. How much energy it takes to do that is widely variable though depending on the tanks dimensions and efficiency. A tank with maximum surface area is going to require maximum energy because the exposed area will drain off the stored heat where a design minimizing area will require minimum energy to maintain the molten temperature.

 

The efficiency of heat transfer into the salt by heat exchangers and out of the salt into a turbine will have a large impact on the overall efficiency of the design. A heat exchanger with a high efficiency will put more BTUs into the molten salt than one with a lower efficiency so it will not lose as much energy in the process. This greatly effects the calculation you are asking about and you haven't mentioned that variable at all.

 

There are many variables in what you ask. Engineering is a very specific, very detail oriented exercise and you've not really provided any specific details about any specific engineering problem in the bigger overall project. Expect funny remarks until you reach the specificity required for real engineering. Engineering is not a guessing game and it is certainly not a discipline where you can assume anything.

 

FWIW, in my own practice of engineering I would probably start with some hard reference material like Marks' Standard Handbook for Mechanical Engineers. In my copy of the 9th Edition it has a whole chapter on the mechanics of solids and fluids, one on heat transfer including a whole section on heat transfer by conduction and convection and a whole chapter on power generation including steam boilers, engines and turbines. You'll get and idea of what calculations need to be done for different parts of the system and it will help provide some of the hard values you need to fill the variables in those calculations.

[hummingbird]

Thanks for the tip on the hand book! I'll probably find useful information from it.