DE1034205B - Corrosion protection process for steam-heated heat exchangers during breaks in operation and a device for this - Google Patents

Description

GERMAN

The invention relates to a corrosion protection method for steam-heated heat exchangers during breaks and a device for this. In such steam-heated heat exchangers that are used to heat air, other gases or liquids, the heating steam generally occurs with more or less high overpressure into the steam chambers, while the condensate below closes drains through a condensate drain. If the heat exchanger is to be put out of operation, the D amp inlet valve closed.

The steam still present in the heat exchanger condenses when the heat exchanger cools down. This creates a negative pressure in the rooms previously filled with steam. This has to As a result, condensate and air in the condensate line are caused by the pressure of the outside air be pressed into the heat exchanger.

The heat exchange surfaces moist from the condensate then come in with the air that has flown in Contact. The air releases the oxygen to the condensate and this to the metal surfaces, whereby these corrode. The iron walls rust in the same way as wet iron rusts in the air.

The aim of the invention is to prevent this automatically in a simple manner. It is known to fill disused steam boilers with softened water to protect against rusting, to which so much caustic soda and phosphate are added that, after good mixing by pumping, a sodium number of about 150O ^{1 is} achieved, which can be determined by the samples taken. Because of its fussiness not come this \ ⁷ out for the present object in question. On the other hand, it is known to let nitrogen or air laden with atomized protective liquid flow into steam-heated heat exchangers after the steam heating has been switched off. The anti-corrosion agent is lost every time the heat exchanger is started up again.

Compared to these known devices and methods, the invention has the advantage that the Corrosion protection fluid not only enters the heat exchanger automatically in a simple manner, but just as easily when the heat exchanger is put back into operation again in a storage container flows back so that it is not lost and used again and again.

The corrosion protection method of the invention for a steam heated heat exchanger in which this is filled with a corrosive fluid during breaks in operation primarily consists of: that the anti-corrosion liquid after closing the steam inlet and condensate outlet

for steam-heated heat exchangers

during breaks in operation

and a device therefor

Applicant:

Dr.-Ing. Paul H. Müller,
Hanover, Eichstr. 33

Dr.-Ing. Paul H. Müller, Hanover,
has been named as the inventor

valve of the heat exchanger by the pressure of the outside air from a container into the heat exchanger is pushed in and. when restarting the heat exchanger after opening the steam inlet valve, before the condensate drain valve is opened, the heating steam presses it back into the container will.

An emulsion of water, especially condensate, can advantageously be used as the anti-corrosion liquid and an anti-corrosion oil can be used, with even small amounts, z. B. 0.5 v. H., the protective oil suffice.

An apparatus for this process is shown in the drawing. A known air heater viewed in the direction of flow of the air is selected as an example of a heat exchanger. With him, the steam enters the steam distribution chamber c through the line α and the shut-off valve b . From the steam distribution chamber c , the steam reaches the heating tubes d, which can also be finned tubes. The steam condenses in them. The condensate enters the condensate collection chamber e, from which it flows through the shut-off valve / to the condensate drain.

According to the invention, this condensate collection chamber e is connected to the lower part of the container g in such a way that the connecting line h opens into the condensate collection chamber e from below. In the upper part of the closed container g , a ventilation valve i is provided which the float k closes when it rises. In addition, the container g is expediently provided with a liquid level glass m and the line h below its confluence with the condensate collection chamber e with a safety container «.

809 577/279

While the air heater is in operation, the. Valves c and f are open and its heating medium spaces are filled with steam, the container g, the line h and the safety container η are filled with an anti-corrosion liquid. The float k is in its upper position and keeps the ventilation valve i closed.

If the air heater is put out of operation, the steam valve c and the condensate valve f are closed. The air heater then cools down and the steam still present in the heating medium space condenses, creating a negative pressure in it. This has the consequence that the anti-corrosion liquid from the container g passes into the heating medium space of the air heater, since the outside air enters the container g through the ventilation valve i when the float k sinks and presses on the anti-corrosion liquid. The passage of this liquid comes to a standstill as soon as the heating medium space of the air heater is completely filled with liquid. The liquid content of the container g is at least equal to the content of the heating medium space of the air heater. Because it is filled with protective liquid, corrosion while it is out of operation is avoided.

When the air heater is to be put back into operation, the steam inlet valve is first opened after the associated fan has been switched on. The steam then presses on the anti-corrosion liquid and drives it back through the thin line h into the container g until the float k rises and the ventilation valve i closes. As soon as you can see from the liquid level glasses m that the liquid has reached its highest level, the condensate shut-off valve / is opened. The air heater is then operational again.

Should some of the protective liquid be lost during the time during which the air heater is out of operation, e.g. B. because of minor leakage of the condensate shut-off valve, the steam will displace some of the liquid in the containment η when it is restarted, but does not penetrate through the line h into the vessel g. During operation, the safety vessel η fills up again with condensate. The low dilution of the protective liquid caused thereby has no effect on the protective effect, since the protective effect, if the liquid consists of an emulsion of water with anti-corrosion oil, is independent of the protective oil content within wide limits.

Since all metal surfaces of the heating steam room from the anti-corrosion liquid during the standstill are wetted, is still during operation, at least during a certain amount of time Time for a protective effect to be present against any corrosive gas content (oxygen and carbonic acid) of the steam. Especially if the air heater is at night, as is usually the case, is out of order, the protective effect is always brought about during the rest period. Most of all will also achieved by the process that when restarting the steam does not have one Finds air filled heating medium space, which would cause corrosion, even if the Heating steam is gas-free per se.

The method and device described can be used for all excess vapor pressures. If the vapor pressure is very low, e.g. only 0.1 atm, the container g may only be placed so high that the highest liquid level in it is no more than 1 m above the lower edge of the condensate chamber e , so that the heating steam pressure can remove the protective liquid from the heating steam room can push the container g over when starting up again. In addition, the container g can be of any height, in particular up to several. Meters below the heat exchanger.

If the heat exchanger is not used to heat air, but rather a liquid that can be dripped, see above the method and the device can be used in the same way.

Claims (4)

PATENT CLAIMS: 1. Corrosion protection method for a steam heated Heat exchanger, in which the heat exchanger with a Corrosion protection liquid is filled, characterized in that the corrosion protection liquid after closing the steam inlet and condensate drain valve of the heat exchanger the pressure of the outside air is pressed from a container into the heat exchanger and at Restarting the heat exchanger after opening the steam inlet valve, before Opening the condensate drain valve is pushed back into the container by the heating steam. 2. The method according to claim 1, characterized in that a corrosion protection liquid Emulsion of water, especially condensate and an anti-corrosion oil is used. 3. Device for performing the method according to claims 1 and 2, characterized in that the container (g ¹ ) for the anti-corrosion liquid is provided with a vent valve (i) at the top, which a float (k) keeps closed in its maximum position while the lower part of the container (g) is connected to the heat exchanger by a line opening into the condensate collection chamber (e) from below. 4. Apparatus according to claim 3, characterized in that below, the condensate collection chamber {e) in the rising branch of the transfer line (h) for the anti-corrosion liquid, a safety container (s) is provided. Documents considered: German Patent No. 847 196; Dr. Arthur Splittgerber, water treatment in steam power plants, Springer-Verlag, 1954. 1 sheet of drawings © 809 577/279 7.58