DE2228901B2 - Humidifying evaporator control - has desludging operated after termination of water infeed to raise water level to the maximum - Google Patents

Abstract

The steam generator is controlled, for air humidification in air conditioning plants. The water level during infeed of fresh water is raised from a minimum to a maximum value, and at intervals a part of the water is fed from the generator for sludge removal, after infeed has terminated. Preferably when the min. level is reached the heating is switched off, and is first switched on again after infeed has commenced. Appts. has a level controller connected to a container for the water to be evaporated, with lower and upper switch contacts. The upper contact is connected to a microswitch above whose upper switch point the water flow is stopped and above whose lower switch point the desludger is set out of action. The simple automatic system prevents dry operation of the heating elements.

Description

55

The invention relates to a method and a device for controlling a steam generator for humidifying air in air conditioning systems, with the water level raised from a minimum to a maximum value while fresh water is being fed in, and part of the water from the steam generator at intervals is discharged to the blowdown.

The steam output of such electrically heated steam generators known from DT-OS 46 610 is around 5 to 30 kp / h. Because of this low The feed water is fed to the steam generator not fed continuously. When a specified minimum water level is reached through evaporation feed water is fed to the steam generator until a predetermined maximum water level is reached. This accumulates during evaporation Water in the steam generator with non-evaporable substances such as salts and the like Part of the water remaining in the steam generator must be drained and drained. The blow-down takes place during the heating and steam generation periods by adding a large amount of water between the minimum and maximum water levels in short time intervals Water is drained from the steam generator, which is less than the amount of fresh water that a minimum permissible fluid level is filled up to a maximum fluid level. This procedure requires a time switch (clock, relay) to turn the water off controls the steam generator releasing organ accordingly. Since the blowdown is independent of the the water level actually present in the steam generator in certain periods of time and only during the evaporation takes place, is when the minimum water level is reached by further switching elements for this Take care that the heating elements do not fall dry. These switching elements and the timer influence the manufacturing costs of the steam generator unfavorable and represent a source of interference for its operation.

The object of the invention is now to develop a method and a device for controlling a preferably electrically operated steam generator for humidifying air in air conditioning systems, thus making it easier Way automatically both a replenishment of the evaporated water and an adjustable blowdown that imperceptibly affects the evaporation Depending on the amount of evaporated water and dry protection of the heating elements in the event of a lack of water is guaranteed.

According to the invention, this is achieved with a method of the type described at the outset in that the discharge of the partial amount of water for blowdown takes place after the end of the feed.

According to the invention, the sludging takes place when the steam generator is completely filled with water. Will contrary to expectations, the blowdown is not ended in time, before the heating elements dry out the minimum water level is reached at which fresh water is fed in. This ensures in a simple manner that the heating elements also are always surrounded by cooling water in the event of faults in the blowdown process.

It has also proven useful to heat the steam generator when the minimum water level is reached switch off and only start up again after fresh water has been fed in. This process step offers the advantage of an additional low water protection and enables while the fresh water is being fed in, it is heated to the evaporation temperature.

An apparatus for carrying out the method according to the invention consists of one attached to the container for the water to be evaporated connected level controller with a lower switch contact for release and an upper sound contact to switch off the fresh water supply and is characterized in that the upper switch contact with a Microswitch is equipped above its upper

Switching point the fresh water feed is prevented and a blow-down device is operated and üThe lower switching point of which the blow-down device is put out of operation.

In an advantageous embodiment of the invention Apparatus comprises the blowdown device a pump, which is opposite to the usual for solenoid valves used for this purpose ensures that the drain lines are not blocked by fixed components, like scale, become clogged. On the other hand, the solid components can also be found in the valve, e.g. B. on its seat and impair its functionality.

An embodiment of the invention will still be discussed Explained in the drawings

F i g. 1 schematically shows a section through a operated according to the method according to the invention Steam generator,

F i g. 2 shows a circuit diagram of a controller constructed according to the invention.

A steam generator for humidifying air in air conditioning systems is shown in FIG. 1 shown schematically and consists essentially of a container 1 which contains water and in the wall of which electrically operated heating elements 2 are attached. At the bottom of the container I a connector 3 and 4 are provided for the supply of fresh water or for blow-down. The generated steam is fed to the air stream to be moistened via a nozzle 5 in the lid of the container 1. When commissioning, the water level in container 1 is topped up to the max level. During the evaporation, which is controlled as a function of the desired moisture content of the air in the air conditioning system, the water level sinks to the level min, which is far above the upper edge of the heating elements 2. When this level is reached, a solenoid valve 5, controlled by a level regulator b \ (FIG. 2), opens, which releases the fresh water supply via the connection 3 into the container 1. If the level falls below min 1, the heating is switched off slightly above level min. The heating is switched on again when the fresh water supply exceeds level min 1. If the water level has risen to the max level, the solenoid valve S is closed to prevent the fresh water supply and a blow-down pump Min operation is set, which pumps as much water out of the container 1 until the water level reaches a max I level slightly below the max level. In the following, on the basis of FIG. 2 describes a circuit with which the method can be carried out in a simple and expedient manner.

The level controller 61 is equipped with a microswitch 10, 11 or 12, 13 at its lower u and upper ο switching contact, the distance between which is adjustable. The distance between the upper and lower switching point of each microswitch forms a fixed, non-adjustable differential. The position of the individual switching points 10, 11, 12 and 13 corresponds to the water level min, min 1, maxi and max in container 1.

If the water level reaches the level min through evaporation, the microswitch 10,11 on the lower switching contact u jumps from switching point 11 to switching point 10 and a relay dl I drops, whereby contactors CI and CII for the heating elements 2 open and the,. Heating elements 2 are switched off, which are thus protected against a lack of water.

When closing the switching point 10, a relay is energized dl, which are even with the water level rises beyond the switching point 12 of the microswitch 12, 13 ο on the upper switch contact and its holding contact remains closed dl Upon energization of the relay nor its auxiliary contact in the current path 20 and the solenoid valve S switched that thereby opens the fresh water supply.If the water level rises as a result of the supply and the level min 1 is exceeded, the microswitch 50.11 on the lower switching contact υ jumps from switching point 10 to switching point 11, whereby the relay dll is energized and its auxiliary contact in the current path 20 closes . In the current path 20, the auxiliary contacts of the relays dl and cfll are now closed, so that the heating protection GI is switched on to heat the water.

If the water level in the container 1 has reached the max ei level, the microswitch 12, 13 at the upper switching point ο jumps from switching point 12 to switching point 13, causing the relay dl to drop out. The solenoid valve 5 thus closes and the supply of fresh water is cut off. At the same time, the blowdown M is switched on, which works until the water level in the tank 1 has dropped to the max I level and the microswitch 12, 13 on the upper switch contact ο has switched from switch point 13 to switch point 12.

The blowdown ratio can be set by changing the switching distance between the lower u and upper ο switching contact of the level controller b \. The blowdown ratio can therefore be adapted in a simple manner to the particular nature of the fresh water, with a small switching distance resulting in a high and a large switching distance a small blowdown ratio.

As from the circuit diagram of FIG. 2, the relay dl] serving as low water protection for the heating elements 2 is only energized when the water level in the container 1 is above the level min 1.

The amount of evaporated water is controlled by an amplifier P depending on the air to be humidified, which opens and closes the circuit for the heating elements 2 accordingly.

For this purpose 2 sheets of drawings

Claims (6)

Patent claims: 1. A method for controlling a steam generator for humidifying air in air conditioning systems, wherein the Water level while fresh water is being fed in from a minimum to a maximum value raised and a part of the water is removed from the steam generator for blowdown at intervals, characterized in that the discharge of the partial amount of water for blowdown takes place after the end of the feed 2. The method according to claim 1, characterized in that when the minimum water level is reached which switches off the heating of the steam generator and this only after the infeed has commenced of fresh water is put back into operation. 3. Device for performing the method according to claim 1, consisting of a level controller connected to the container for the water to be evaporated with a lower switching contact for enabling and an upper switching contact for switching off the fresh water supply, characterized in that the upper switching contact (o) is equipped with a microswitch (12, 13), via its upper switching point (13) the Fresh water feed is prevented and a blow-down device (m) is operated and over whose lower switching point (12) the blow-down device is put out of operation. 4. Apparatus according to claim 3 for performing the method according to claim 2, characterized in that the lower switching contact (υ) of the level controller (bl) equipped with a microswitch (10, 11) with an upper (11) and lower (10) switching point is, whereby when the lower switching point (10) closes via a falling relay (dl I) the heating is switched off and an energized relay (<Λ) opens a solenoid valve (S) to enable the fresh water feed and when the upper switching point (11 ) the relay (JII) is energized again and the second relay (dl) closes a circuit supplying the heating. 5. Apparatus according to claim 3 or 4, characterized in that the switching distance between the upper (o) and lower (o) switching point of the level controller (W) can be set. 6. Device according to one of claims 3 to 5, characterized in that the Abschlämmein direction comprises a pump (M).