JP3893178B2 - Cleaning method for power generation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention relates to a method according to the superordinate concept part of claim 1.
[0002]
[Prior art]
In power generation facilities, especially gas-steam-power generation facilities, steam conduits, evaporators, superheaters, etc. must be cleaned. The ultimate goal of such cleaning, usually performed before the first run, is to protect the devices, especially fluid machines, such as steam turbines, from contamination that inevitably occurs during assembly or repair of the system. . The technical term “blowing out” is conventionally used for these processes.
[0003]
Basically, two methods are known. That is, a method of continuously cleaning at a high dynamic pressure ratio and a method of causing a large thermal shock by a periodic blowing out surge.
[0004]
Good blowing effect can be obtained quickly by continuous blowing out at high dynamic pressure. However, for example, if the steam system to be cleaned cools and is subsequently loaded with steam for further cleaning, a very effective additional cleaning effect is recognized by thermal shock. This can be evaluated as a sign that dirt was still present in the steam system. This method of using high dynamic pressure attempts to create a thermal shock by injecting water before the superheater or into the superheater itself. The occurrence of thermal shock effects downstream of the superheater in the steam conduit is very slight. Also of particular importance to such measures is the fact that many waste heat boiler manufacturers have expressed opposition to injecting water before or during the superheater. There is no doubt that blowing out by a thermal cycle also has the decisive drawback of taking a long time to perform the method.
[0005]
Cleaning time of almost 20 days must be provided for blowing out by thermal cycle of a conventional medium power generation facility with two waste heat boilers. On the other hand, continuous blowing out at a high dynamic pressure ratio requires only about 3 to 5 days. In this case, however, the cleaning effect is no longer very high.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to significantly enhance the cleaning action and to significantly reduce the blow-out time in a method of the type described at the outset.
[0007]
[Means for Solving the Problems]
According to the invention, the above problem is solved by means having the features of claim 1.
[0008]
【The invention's effect】
An important advantage of the present invention is recognized in that the advantages of the methods described above are exploited without causing the disadvantages associated with these methods.
[0009]
In the method of the present invention, blowing out is performed for several hours using high dynamic pressure. The blowing out time in this case depends on the supply of water from which minerals used for steam generation have been removed or on the production volume. Thus, for example, blowing out takes place at night, whereby the system is cooled during this time and a water preparation facility is used to prepare new, demineralized water for the next blowing out. Subsequent blowing out in this case causes a thermal shock that results in a large cleaning effect as described above. After cooling, the continuous blowing-out is repeated with high dynamic pressure each time, and the large cleaning effect of the preceding thermal shock is strengthened. In this case, only a few cycles are required for sufficient cleaning effect. Absent.
[0010]
Further advantageous configurations of the solution to the problem of the invention are as set out in the further claims.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this case, both the conventional method and the method of the present invention are shown in order to clarify the features of the present invention over the prior art and to understand the present invention. Items that are not necessary for a direct understanding of the invention are omitted. The same method steps are denoted by the same reference symbols in different figures.
[0012]
FIGS. 1a and 1b show a cleaning method belonging to the prior art with a short cycle of blowing-out surge that produces a large thermal shock to a group of power generation equipment in the assembled state. The individual blowing-out surges A and B are carried out for about 12 hours in total by an appropriate medium as shown by the horizontal axis t in the figure. The temperature T of the medium used is approximately 500-550 ° C., whereas the dynamic pressure ratio P is> 1. The advantages and disadvantages of such a blowout method have already been described. In short, blowing out by this thermal shock cycle produces a good cleaning effect, but the long time required for this is unacceptable from the modern point of view of making maximum use of the power generation equipment.
[0013]
FIGS. 2a and 2b belong to the prior art for cleaning a group of power generation equipment in the assembled state by continuous blowing out, indicated by curves C, D on the horizontal axis indicating time. The cleaning method is shown. While the temperature T of the medium used remains relatively low, 400 ° C., in this case, blowing out is performed at a high dynamic pressure ratio P of about 3. The advantages and disadvantages of this blowing-out method are already described. In short, in the continuous blowing-out method using a relatively high dynamic pressure ratio, a good cleaning effect can be achieved quickly, but since there is no occurrence of thermal shock, thorough removal of the adhered dirt portion cannot be obtained.
[0014]
Figures 3a and 3b show the cleaning method according to the invention of a group of power generation equipment in the assembled state. In this method, the operation is carried out at an average temperature T above 400 ° C. and a dynamic pressure ratio P of approximately 4 and higher. This operation is performed by blowing out as shown by curves E and F over several hours as can be seen from the section on the horizontal axis t. In this case, the blowing-out time mainly depends on the amount of prepared and stored water from which minerals necessary for generating steam are removed or the amount of production. Thus, for example, a blowout is performed at night, so that the system to be cleaned is cooled during this time and the water preparation facility is used for subsequent blowout minerals before the process is performed again. Water from which water has been removed can be prepared. Subsequent blowing out (see curves E and F), which takes place over several hours at a high dynamic pressure ratio P, enhances the high thermal shock cleaning effect. The high dynamic pressure ratio during blowing out is caused by the high speed. A high speed is created when there is a low pressure in the system to be cleaned and thus a relatively large specific volume. Such a condition is advantageously obtained by providing a silencer with a very low pressure loss in a temporary conduit and injecting water into the conduit. This injection of water directly at the beginning of the temporary conduit creates a low pressure in the system to be cleaned and at the same time a large amount of steam conditioning. As a result, this method has the additional effect that is also observed in the method shown in FIGS. 2a and 2b. That is, the temporary blowing out conduit is not subject to significant stress as in other methods belonging to the prior art. The advantage over the method shown in FIGS. 2a, b is that the water consumption is small. This is because in many cases the amount of water available is limited. Yet another advantage of the method of the present invention is that it is only about 5 starting and stopping loads, compared to the method according to FIGS. 1a and b where the gas turbine must be subjected to starting and stopping loads up to 50 times. The gas turbine is significantly protected.
[Brief description of the drawings]
FIG. 1 is a diagram showing a graph of a blowing out method belonging to the prior art. FIG. 2 is a diagram showing a graph of another blowing out method belonging to the prior art. FIG. 3 is a diagram showing a graph of a blowing out method according to the present invention. Explanation of symbols]
T Facility temperature t Time p Dynamic pressure ratio A Thermal shock in relation to temperature T, number of times, duration B Thermal shock in relation to dynamic pressure ratio p, number of times, duration C Continuous blowing out in relation to temperature T , Duration D continuous blowing out in relation to dynamic pressure ratio p, duration E thermal shock in relation to temperature T—continuous blowing out, duration F thermal shock in relation to dynamic pressure ratio p—continuous blowing out, Duration

Claims (6)

In a method for cleaning a group of power generation equipment in an assembled state by blowing in a medium, a thermally prepared medium under pressure is blown in for several hours, followed by a pause process following this method step. The power generation equipment is characterized in that the apparatus group is cooled during the pause process, and after the apparatus group is cooled, at least one further blowing is performed intermittently to produce a cleaning effect by a thermal shock. Cleaning method for various devices. The cleaning method according to claim 1, wherein the blowing is performed for a period of at least 6 hours. The cleaning method according to claim 1, wherein the medium is blown at a temperature higher than 400 ° C. and a dynamic pressure ratio higher than 3. The cleaning method according to claim 1, wherein steam is used as the blowing medium. The cleaning method according to claim 4, wherein water is mixed with the steam. 5. Cleaning method according to claim 4, characterized in that the water is put together into the group of devices to be cleaned in parallel with and / or before or after steam blowing.

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