EP0776707B1 - Method of cleaning aggregates from a power plant - Google Patents

Description

Technical field

The present invention relates to a method according to the preamble of claim 1.

State of the art

In power plants, especially in combination plants (Gas / steam power plants) needs cleaning, especially the steam line, the evaporator, superheater, etc., be provided. The final purpose of such usually precedes The first commissioning of cleaning operations is on the protection of the units, especially the turbomachines, for example the steam turbine, before the dirt, which inevitably during assembly or revisions of the mentioned systems. The terminology used here for this process is called "blowing out".

Basically, two methods have become known: either is continuously with a high back pressure ratio cleaned, or there are cyclical blowouts large thermal shocks triggered.

When blowing continuously with high dynamic pressures quickly achieved a good cleaning effect. But if that For example, the steam system to be cleaned cools down and then steamed again for further cleaning thermal shock becomes an effective, additional one Cleaning effect found. This can be a sign be assessed that there is still dirt in the system was. Tried the high back pressure ratio method a thermal shock by means of water injection before or in the superheater to do it yourself. The triggering of this effect a thermal shock downstream of the superheater in the Steam pipe is classified as low. Which is also important against such an approach is the fact that many waste heat boiler manufacturers are in the specifications against water injection before or between the superheater turn. When blowing out with thermal cycles it is allowed to Beyond that, don't be misjudged that crucial The disadvantage of this is the large amount of time required for the implementation of the procedure.

With a combination system of medium performance and more conventional Kind with two waste heat boilers would have to be blown out with thermal cycles a cleaning time of approx. 20 days can be provided. When blowing continuously with high dynamic pressure ratios you only need about 3 to 5 days, whereby the cleaning effect is no longer so great.

Presentation of the invention

The invention seeks to remedy this. The invention how it is characterized in the claims, the task lies the basis for a procedure of the type mentioned at the beginning Maximize cleaning effect and minimize blow-out time.

The main advantage of the invention is that that only activated the advantages of the above methods without including their disadvantages have to.

In the method according to the invention, high back pressures are used blown out for several hours. The blow-out time depends here from the Demi water supply resp. whose production starts from is used for steam production. After that, for example blowout set overnight so that System cool down during this time and the water treatment system new demi water for the next blowout Can provide. The subsequent blow-out causes then a thermal shock that, as described above, causes a triggers great cleaning effect. The subsequent repetition of continuous blowing out with high back pressures after the respective cooling, sometimes the larger ones Cleaning effect of the previous thermal shock, whereby for effective cleaning only a few cycles are required.

Advantageous and expedient developments of the inventive Task solutions are characterized in the other claims.

In the following, an embodiment will be made with reference to the drawings illustrated and explained in more detail, wherein for delimitation and for better understanding compared to the State of the art two methods are included. All not necessary for the immediate understanding of the invention Information has been omitted. Same process steps are the same in the different figures Provide reference numerals.

Brief description of the drawings

Fig. 1a, 1b

eine graphische Darstellung eines zum Stand der Technik gehörenden Ausblaseverfahrens,

Fig. 2a, 2b

eine graphische Darstellung eines weiteren zum Stand der Technik gehörenden Ausblaseverfahrens,

Fig. 3a, 3b

eine graphische Darstellung des erfindungsgemässen Ausblaseverfahrens.

It shows:

1a, 1b

a graphical representation of a blow-out method belonging to the prior art,

2a, 2b

a graphical representation of another blow-out method belonging to the prior art,

3a, 3b

a graphic representation of the blow-out method according to the invention.

WAYS OF CARRYING OUT THE INVENTION, INDUSTRIAL APPLICABILITY

1a and 1b show one of the prior art Process for cleaning units of a power plant in the installed state by means of short cyclical blow-out blows, which in themselves trigger a large thermal shock. The individual blowouts A, B using a suitable Medium take place approximately every 12 hours, like this Abscissa expresses t. While the temperature T of medium used is about 500-550 ° C, the back pressure ratio p moved to> 1. Regarding the different Advantages and disadvantages of such a blow-out process reference is made to the introduction to the description. Briefly recapitulated can be said that the blow out with Thermal shock cycles triggers a good cleaning effect that the time required for this appears according to modern criteria with a view to maximizing the availability of the Power plant to be prohibitive.

2a and 2b show a further part of the prior art Process for cleaning units of a power plant in the installed state by means of a continuous Blowing out, like this the curves C, D on abscissa t, applied in hours, show. While the temperature T of medium used remains relatively deep, below 400 ° C, is here with a high dynamic pressure ratio p of worked about 3. Regarding the pros and cons of this Blow-out procedure is also based on the introduction to the description referred. In short it can be said that in the continuous blow-out process with relatively high Back pressure conditions in themselves very quickly a good one Cleaning effect is achieved, the decisive breakaway of adhering dirt parts is meanwhile because of the missing Thermal shock not reached.

3a and 3b show the method according to the invention for Cleaning aggregates of a power plant in the built-in Status. This procedure uses medium temperature T, above 400 ° C, with a high dynamic pressure ratio p of worked about 4 and higher. This is done by using several Hours as the division on the abscissa t symbolize wants to be blown out, as is the case with curves E, F emerges. The blow-out time essentially depends from the Demi water supply or whose production from that for Steam production is needed. After that, for example blowout set overnight so that the system during cool down this time and the water treatment system new demi-water is available for subsequent blowing out can put before the procedure resumed becomes. The thermal shock triggered with each blowout causes a great cleaning effect. The subsequent one Blow out over several hours (see curves E and F) with high dynamic pressure ratios p increases the large cleaning effect of thermal shock. High dynamic pressure ratios during blowing out by high speeds evoked. High speeds arise when in system to be cleaned small pressures and consequently larger ones prevail specific volumes. Preferably be these relationships created by in the provisional Pipelines one silencer with very little pressure loss and for this a water injection is provided. This Water injection directly at the beginning of the provisional pipes causes a small pressure in the system to be cleaned, with a large conditioning of the steam. This results in an additional one with this method Effect that can also be found in the method according to FIGS. 2a, 2b: The provisional blow-out lines are not like those other large processes belonging to the prior art Subject to tension. An advantage over the process 2a, 2b here is the lower water consumption, because it often shows that the available water is limited. Another advantage of this procedure can be seen in the fact that the gas turbine is significantly protected is, in contrast to the method according to Fig. 1a, 1b, in which the gas turbine is started and stopped up to 50 times only a load of about 5 times Start and stop is subject.

Reference list

T

Plant temperature

t

Time, duration in hours

p

Back pressure ratio

A

Thermal shock, number, duration, in relation to temperature T

B

Thermal shock, number, duration, in relation to the dynamic pressure ratio p

C.

Continuous blowing, duration, in relation to temperature T

D

Continuous blowing out, duration, in relation to the Back pressure ratio p

E

Thermal shock / continuous blowout, number, duration, in relation to the temperature T

F

Thermal shock / continuous blowout, number, duration, in relation to the dynamic pressure ratio p

Claims (6)

1. Method of cleaning units of a power plant in the installed state by injecting a medium, characterized in that the thermally processed medium under pressure is injected for several hours, in that a rest phase, during which the units cool down, is included following this step of the method, and in that, after the units have cooled down, at least one further injection is carried out intermittently, which further injection initiates a cleaning effect by thermal shock.
2. Method according to Claim 1, characterized in that the injection is carried out over a period of time of at least 6 hours.
3. Method according to Claim 1, characterized in that the medium is injected at a temperature of greater than 400°C and a dynamic-pressure ratio greater than 3.
4. Method according to Claim 1, characterized in that the medium used for the injection is steam.
5. Method according to Claim 4, characterized in that a water quantity is admixed with the steam.
6. Method according to Claims 1 and 4, characterized in that, in parallel with the steam injection and/or before or after the steam injection, a water quantity is also introduced into the units to be cleaned.

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