HP Steam to MP Steam

High pressure to medium pressure, I would guess. If you tried to drive the turbine via HP to LP (low pressure), that might be too much pressure difference for the turbine to withstand. (I'm not a steam expert, but there are counterpart situations in 2-stage refrigeration.)

There are turbines that go from HP to vacuum so pressure difference is not an issue. As Kaisan said it is a matter of steam balance, and what steam you need at what pressure. Basically in this case they are using the compressor train as a let down station.

Remarkably efficent those steam engineers....

Tornado is right.

Your steam turbine uses steam from the HP (High pressure) header and exhausts into the MP (Medium Pressure) steam header.

You could also have many other combinations, HP to condensate, with or without extraction to HP and and or LP, MP to LP etc.

The choice of which type to use is determined by the steam balance of the plant.

In your case the turbine is producing useful work to drive the compressor and is at the same time letting down the steam pressure to HP to supply some other process need. If you had no need for the MP steam then another type of steam turbine would have bee specified.

I know lots of Steam Engineers and none of them have heard of MP steam. LP is below 15 psi and anything above 15 psi is high preasure steam.

Taz

Ok maybe in Canada in your industry that is the case. In other parts of the world the term is used.

Generally- LP (low pressure) steam is 15 PSIG of lower

HP (high pressure) steam is a little trickier- Some consider HP to be 150 PSIG or higher, others start at up to 600 PSIG (with or without superheat)- keep in mind that coal fired power plants operate at about 2300 PSIG with superheat

Usually, MP (medium pressure) falls at either 30 to 150 PSIG - or 30 to 300 PSIG, depending on your starting point.

Very well put Kaisan! GA from me.

Thanks every one for your help and patience~~ been great help to me .

Hi Guys,

Actually, as a steam plant designer for a number of companies around the world, I can say there is no strict definition for labelling steam pressure levels. As a general rule of thumb, there are four pressure levels generally used. The actual delineation between them varies from place to place and company to company. In North America, these levels generally have a common theme:

Low Pressure (LP) steam - use ASME 150 pound flange

Intermediate Pressure (IP) steam - use ASME 300 pound flange

Medium Pressure (MP) steam - use ASME 600 pound flange

High Pressure (HP) steam - use ASME 900 pound flanges and up

Steamerst

GA - I agree, I have been in plants where HP = 45 bar, MP = 17 bar, and LP - 5 bar. In another HP (sometimes referred to as VHP - Very High Pressure) was 120 bar, MP-45 bar and LP-5 bar.

No strict definitions, just common usage which is understood on a specific plant.

The answers are correct in interpreting the meaning HP to LP means High pressure inlet to Medium pressure outline line. The exhaust or outlet end of a back pressure turbine is piped to the Medium pressure steam system providing that is the exhaust pressure the turbine is designed for.

Back pressure turbines are often used in turbo-generator sets and have the dual function of acting as a reducing valve in taking high pressure steam, converting the thermal energy into electric power, and providing a source of medium to low pressure steam for other uses.