Ball valve for thermal power plants

[Rustam1]

Dear all!

How do I know the use of ball valves in thermal power plants is limited due to:
-high torque on the shaft of the ball at the opening due vapor or water high-pressure, because "floating ball";
-high wear a ball or seats at the half-open state, so easily damaged.
Maybe I missed something.

Question:
Will ball valves are promising, if:
-ball mounted on of trunnion on sliding bearings; in this case, the torque will be much smaller;
-ball and seats are made entirely of hard and wear-resistant ceramic or ceramic-metallic materials, such as silicon carbide, zirconium oxide, tungsten carbide-cobalt or of titanium carbide-niсkel.

Thanks.

 

[gerhardl]

Hello Rustam1,

Generally you should only use valves in 'thermal power plants' that are tested, approved, certified and/or used with longtime references for the exact application you need them for. Anything else is a game with lives, safety and cost.

(Not knowing anything about size, pressure, temperature and fluid (overheated stem, saturated steam, steam/condensate) and anything else it is not possible to comment further.)

 

[Rustam1]

Hello Gerhardl,

Thank you for reply.

Currently there used the global valve, for example, DN20mm. Operating modes not more, as an example: the water, the pressure of 373 bar, a temperature is 280 С degrees; or vapor, the pressure of 250 bar, a temperature is 545 C degrees.

The main drawback of global valve - high hydraulic resistance downstream when open - coefficient more than 5.0 .

The advantage of the ball valve - the virtual absence of hydraulic resistance when open - coefficient less than 1.2 .

This enables significant energy savings on the regulation of the stream. Moreover, the ball valve has a small size and weight.
Advantageous to replace the global valve on the ball valve.

Therefore, the question arises - why, in principle, do not change the global valve on the ball valve?

Thanks.

 

[gerhardl]

You are correct in your views. The problem is to find a ready available commercial solution, covering your demands. As you have already observed, extreme pressures needs special constructions, and demands on construction and material increases the higher the temperature is. Searching the net for suppliers would be a sensible Way.

http://kopecs.com/products/04_desuperheater_high_temperature_valves.htm

might have what you are looking for.

Using the keywords for search you might find other suppliers.

 

[moltenmetal]

I trust you mean a globe valve, not "global".

High temperature metal seated ball valves are sometimes used in power plant applications. Yes, they have high rotational torques, and no they're not very good for use in the partially open position.

https://www.velan.com/en/products/power-ball-valves.html/1/51

(the link is provided simply because the product's name reflects its use in power applications)

Generally a metal-seated ball valve is used for block valve applications where actuation is required. Manual valves in these services are usually gate rather than ball valves- they accomplish many of the same goals but for a greatly lower price.

There are MANY vendors who have entered into this market in the past decade, trying to climb up-market from the commodity business of soft-seated ball valves. Some manufacturers are better at it than others. Materials selection, coatings selection and application, design AND skill in manufacturing are all required to achieve successful results.

If you're throttling/regulating a flow, or it's important beyond other factors that the valve open gradually without damage, the globe valve is still king. Y pattern manual globe valves are sometimes used for high temperature and high pressure block applications, but do suffer from the disadvantages you've mentioned.

 

[Rustam1]

Hello, moltenmetal and gerhardl,

I apologize for the delay in response.
Automatic information about your response I have not received.

Yes a globe valve, not "global" - this is my mistake.
Probably, i am will have many mistakes, because i in stage study english.
Please, specify on my mistakes.

I want to give an explanation - in what is my task?
We have developed a solid and wear-resistant ceramic-metallic material (cermet) on titanium carbide base.
Bundles - nickel alloys and stainless steels.
Method - infiltration of the porous semifinished titanium carbide with metal melt in a vacuum or inert atmosphere.
This method is known for a long time, but we have improved the technology.
Advantages - the combination of sintering and infiltration operations, the complex shape workpiece, minimum allowances and labor content on grinding.
Hardness 62-70 HRC. Cermet is an analogue of hard alloy WC-Co.
Purpose - abrasive, corrosive environment, work temperature up to 1100 C.

The cost of manufacturing 2-2.5 times lower compared with hard alloy WC-Co, and 2-2.5 times higher in comparison with steel. Wear resistance compared with steel above is not less than 10 times.

We decided to use the technology in the gates of valves.

Ball valves with DN50 mm out of the cermet (the replacement of gate valves) 3.5 years working without a problem at our local refineries (Ufa, Russia).

Gate valves are removed every six months and repaired (grinding seat and wedges etc.).

We in Russia in thermal power plants (high pressure and temperature of the water or steam) used only the shut-off valve and gate valve. Ball valves are not used.

On the local thermal power resource regulating globe valves DN20 mm is 2-3 months. Stocks and seat are made of steel with a hard surface, or surfacing. Under the pressure of 150-200 bar and water temperatures up to 230-270 C stocks and seat quickly "washed out" and fail. They ready to use ball valves, but after all the tests. Otherwise - very dangerous.

It turns out, in the world is the same situation - the ball valves no used in thermal power stations.
One thing is clear - to replace the shut-off valve in the ball valve will be very difficult.
The pessimist thinks - ball valves are not used, so there is no market.
However, the optimist thinks - the market of ball valves big and need to promote them on the market.

I'm the head of the innovation project and I'm looking for an investor. Required investment - $2.5 million. One investor is, but need a second. We have to show that in addition to oil refining, mining, metallurgy, etc. there are additional markets and the risks of investing money are minimal.

That's why I'm trying to find new areas of use cermet and show a large market for the new product.

Thank you all for your answers.

 

[gerhardl]

Hello Rustam1,

This explains a lot. It seems very impressive what you have developed. I am not very familiar of use within the high temperatures combined with the high pressures you describe. In general your qustion is a classical case of new developed technology versus an existing market.

We 'technologists' will sometimes get stuck in certain ways of using new technological development for given products.

Some points you could consider:
1. Using active blocking valves (globe/gate) for dangerous fluids are worldwide accepted, and would, even with tests, be difficult to overcome (rules, insurance etc.)
2. Other areas where wear and abrasion is a problem, but not necessarily temperature could be a posibillity.
3. Layers on advanced regulation valve parts could be interesting.
4. What other products (outside valve industry) uses, or could use, the material and technology?

The answers for getting investors could be in other areas than you have thought, but a broad, general, market research may be the cheapest start.

Good luck!

 

[Rustam1]

You right, it is necessary to consider different options and to study the market well. We will consider the possibility of manufacturing of products, specified by you.

The technology enables to produce individual items (parts) of cermet (with metal tides) and their welded together.

We also think to use a cermet for the manufacture of centrifuges screws for the water separation of the powder material (mining industry), extruders for pressing ceramic and metallic materials (MIM and CIM technology in mechanical engineering) and machines for the production of hollow concrete slabs (construction industry).

Thank you for your recommendations.