DE102017130110A1 - Liquid treatment plant and method for its operation - Google Patents

Abstract

The invention relates to a device for processing a raw liquid (1), in particular of water, in which by means of heat exchangers (3) the crude liquid (1) is distilled, and a method for operating the same. The heat exchanger (3) are connected to means (4) for detecting a vibration as well as to means (5) for exciting the heat exchanger (3) to forced oscillations. An evaluation unit (7) evaluates the vibrations of the heat exchangers (3) detected by the means (4) for detecting a vibration with regard to the determination of an operating state. By means of the means (5) for exciting the heat exchanger (3) to forced oscillations, both during operation, the evaporation and the removal of impurities during a cleaning cycle can be supported.

Description

The invention relates to a device for the distillation of liquids, in particular for the treatment of water for the production of drinking water, and a method for operating such a system, in particular for the removal of deposits that accumulate in a water treatment plant during their operation.

The steady increase in the world's population brings with it an ever-increasing demand for water, both to supply people with drinking water and to irrigate fields and livestock. Due to climate change, this situation is exacerbated, especially in arid areas. Although the use of surface or groundwater is usually cost-effective, it can only be used in the presence of appropriate water resources. Their exhaustion is also a critical problem worldwide.

It is known to recover water by dehumidifying air. Such devices, however, rely on moist air, water production is not possible on a larger scale.

Furthermore, it is known to recover water by means of desalination of seawater. Currently, about 1% of the world's population depends on seawater desalination to meet their daily water needs. However, the UN estimates that by the year 2025, about 14% of the world's population will be dehydrated, so that seawater desalination will become increasingly important. Especially for dry countries, seawater desalination is important, such. For example, Australia, where rainwater is traditionally collected by means of dams.

The prior art discloses methods and devices which separate seawater into the components salt or brine and drinking water, so that these are largely used either for drinking water or salt production.

One embodiment of such systems are so-called MVC systems (Mechanical Vapor Compression). In such plants, seawater is partially evaporated, leaving the salt in the brine. The resulting vapor is compressed so that its phase change temperature increases. He is now fed back to the evaporator and serves as heating steam. It condenses, with the condensate representing the product water. DE 10 2007 028 129 B4 For example, describes a very effective method for operating such a system.

Another method of seawater desalination is the MED (Multiple-Effect Distillation). Here, the raw water is passed through several stages, the so-called "effects". Water is sprayed on pipes through which steam is passed. As a result, the water evaporates and this steam is used in a next stage again for heating raw water. This process is considered to be the most thermodynamically efficient since steam or waste heat from nearby industrial plants can be used.

A general problem of water treatment plants is their contamination by the deposition of lime, salts or biogenic residues. These affect z. B. the transport of heat in heat exchangers.

The need for cleaning has hitherto only been recognizable by means of reduced water production rates or complex laboratory tests. For cleaning are often aggressive liquids such. As alkalis or acids, passed through the equipment. However, this requires a subsequent thorough flushing to avoid contamination of the drinking water to be produced. In addition, the cleaning in the usual way by means of a backwashing, in which the system "backwards", d. H. is flushed against the flow direction present in operation.

The invention has for its object to provide a method for operating a liquid processing system in which a targeted cleaning should be done only in case of need and without the use of aggressive chemicals or a backwashing process. In addition, a liquid treatment plant is to be provided, which allows effective cleaning with low and cost-effective use of chemicals as needed.

This object is achieved by the method with the features of claim 1 and the liquid processing system with the characterizing features of claim 7; expedient developments of the invention will become apparent from the claims 2 to 6 and 8 to 11th

According to the invention, a method for operating a liquid treatment plant, in particular a water treatment plant for the recovery of fresh water, and a liquid treatment plant, in which the degree of contamination by detecting and evaluating vibration conditions, in particular the heat exchanger, and at least the cleaning is carried out with vibration support, provided.

Preferably, the method is applicable to liquid treatment plants, the at least a heat exchanger in the form of an evaporator, in which the raw liquid to be cleaned, for. As seawater is at least partially evaporated with heat and / or pressure reduction.

According to the invention, the vibrations occurring during operation of the system are detected by means of vibration sensors. The vibration sensors are preferably attached to the heat exchanger (s).

Advantageously, vibration sensors are used which can detect vibrations in a wide frequency range and convert them into an electrical signal. This electrical oscillation signal can be converted by an evaluation device, which is for example part of a control and regulation unit of the liquid treatment plant, into a discrete frequency spectrum, in which discrete frequency values are each assigned an amplitude value, or a quasi-continuous frequency spectrum. Such a conversion is carried out by known methods, for. B. a discrete Fourier transform.

The (discrete or quasi-continuous) frequency spectrum is, for. B. from the evaluation, analyzed with respect to a temporal change of frequency and / or amplitude of predetermined vibration modes. These predetermined vibration modes may be resonant frequencies of the liquid treatment plant, the heat exchanger or other components of the system. As oscillation modes and predetermined frequency ranges can be understood, which extend quasi-continuously from a start frequency to a final frequency.

The temporal changes of frequency values (i.e., frequency shifts) and / or amplitude values (i.e., the increase or decrease in the vibration intensity at the corresponding frequency) are thus detected as change values during operation.

If one or more of these change values exceeds a given limit, an event is triggered. Performing a cleaning cycle is one such event.

To carry out a cleaning cycle, a cleaning liquid is introduced into the liquid treatment plant. In this case, the supply of the raw liquid to be reprocessed can be stopped in the system, so that (after a certain exchange time of the liquids) only the cleaning liquid passes through the system. Alternatively, the cleaning liquid can be admixed with the raw liquid to be processed so that a mixture of cleaning liquid and raw liquid passes through the system.

With the introduction of the cleaning liquid, the operating pressure and / or the operating temperature are changed at least in individual components of the liquid treatment plant. The components of the liquid treatment system to be considered for this purpose are preferably the heat exchangers. For example, the operating pressure in the entire system can be increased. Alternatively or additionally, the operating temperature, for. B. in predetermined heat exchangers of the system, changed, for. B. lowered, be.

In addition to the measures described above, during the cleaning cycle at least individual components, eg. B. the heat exchanger, the liquid treatment plant by means of vibration excitation, d. H. Vibration generator, forced to forced vibrations with predetermined frequencies. It can be provided to excite with only one discrete frequency, wherein a separate frequency value can be provided for each component to be excited. It can be provided to pass through a series of frequencies one after the other (so-called "chirp"), but it can also be excited in a frequency band, wherein for each component a respective dedicated type of vibration excitation can take place.

As a cleaning liquid is z. As an alcohol used. After completion of the cleaning cycle, the cleaning liquid is distilled again by appropriate adjustment of the operating parameters pressure and temperature. Advantageously, the cleaning liquid can thus be reused.

The advantage of the method according to the invention is an efficient cleaning, wherein due to the vibration support and fixed encrustations can be solved waiving aggressive chemicals and transported away from the liquid flowing through. Thus, the complex backwashing can be omitted, the cleaning is virtually during the operation of the system.

According to one embodiment of the method for operating a fluid treatment system, the vibration sensors are also used to generate the forced vibrations. For example, devices are used which detect vibrations in a first operating mode and can generate vibrations in a second operating mode.

It can be provided that the vibration spectrum detected during operation of the liquid treatment system can only be applied to selected eigenmodes, eg. B. the heat exchanger, is evaluated in terms of frequency shift or vibration amplitude. If a predetermined limit value for the frequency shift and / or the amplitude change of the eigenmodes is exceeded, then a cleaning is initiated.

In particular, it may be provided to detect the vibrations in relation to the frame of the liquid treatment plant at each heat exchanger and to analyze them separately for each heat exchanger.

According to one embodiment, at least one reference oscillation spectrum or reference Fourier spectrum is created by the vibrations of the components to be monitored, for. B. the heat exchanger, over each a reference period of time to be detected (eg, during the regular, error-free operation of the system or after their initial start-up or heavy pollution).

According to this embodiment, reference vibration spectra or reference Fourier spectra can be learned automatically in a learning phase, for. For example, by determining spectra over a plurality of operating period durations, comparing them with one another and forming them from the same reference oscillation patterns (eg by averaging) if these spectra match sufficiently. A reference vibration pattern may be in the form of a reference vibration spectrum or a reference Fourier spectrum, wherein a reference vibration pattern may also be limited to individual, predetermined frequencies or frequency ranges.

One or more reference spectra thus allow the definition of reference vibration patterns, each reference vibration pattern a specific operating condition, eg. B. "clean" or "dirty", the respective component or system describes. Thus, a classification into typical patterns or pattern types and their classification is possible, with a defined plant and operating state, a corresponding pattern can be assigned and these patterns change with changes in the condition of the system or individual components.

In particular, a degree of contamination of the heat exchangers can be determined by comparing a vibration pattern recorded during normal operation of the system with these reference vibration patterns. For this purpose, an automated pattern recognition, z. B. by an evaluation of the control and regulation unit, are used.

The invention may be further configured such that based on the analysis of the vibrations -. B. by comparison of the detected vibration pattern with reference vibration patterns - one or more operating parameters, such as temperature, pressure, mass flow and / or admixture of additives to the raw liquid to be adjusted or changed during operation of the liquid processing system. As a result, the detected vibration behavior can be used to control the system in an advantageous manner.

In an advantageous embodiment of the method according to the invention takes place during normal operation of the liquid processing system, d. H. outside the cleaning cycles, an excitation of individual components, eg. As the evaporator, forced vibrations. This can permanently oscillations with a frequency above 16 kHz, d. H. in the ultrasonic range, be stimulated. Due to this vibration excitation in the ultrasonic range, vaporization of the fluid can be promoted due to the formation of bubbles.

Alternatively or additionally, a cyclic excitation with vibrations of predetermined frequencies, for. B. resonant frequencies of the excited evaporator, take place. As a result, contamination of the evaporator can be slowed down effectively, so that cleaning cycles are less frequent.

The liquid processing system according to the invention comprises at least one heat exchanger mounted on a frame for the at least partial evaporation of a raw liquid, a control and regulation unit with - preferably integrated - evaluation device, means for detecting a vibration and means for excitation to forced vibrations. The means for detecting a vibration and the means for the excitation to forced vibrations are arranged at least on the one or more heat exchangers.

Preferably, the means for detecting a vibration and the means for exciting forced vibrations as a structural unit, for. As a vibration detecting and generating element. These can be piezoelectric elements which generate an electrical voltage when a mechanical force acts or, when an electrical voltage is applied, execute a mechanical movement. Thus, by reading the vibrations of the heat exchanger of the piezo elements generated voltage curves detects the vibrations and imposed by applying a corresponding voltage waveform to the piezoelectric elements, the heat exchangers forced oscillation.

Advantageously, the heat exchangers are mounted on the means for detecting a vibration and the means for excitation (the heat exchanger) to forced oscillations, so that a vibration of the heat exchanger in relation to the frame can be detected and the heat exchanger due to this type of storage to exactly predetermined Vibrational patterns are excitable.

The electrical energy for operating the liquid treatment plant, in particular the vibration generator and the control and regulation unit can be provided by connecting the system to a public power grid. Preferably, however, the liquid treatment plant has its own, self-sufficient power generation unit, the current, for example, from solar energy z. B. by means of photovoltaic cells, or from wind energy, for. B. by means of a rotor with aerodynamic rotor blades wins.

The heat energy needed to evaporate the raw liquid can be waste heat from nearby industrial plants.

In addition, it can be provided that the liquid processing system has a storage device for storing electrical current, ie. H. a rechargeable storage for electrical energy, eg. B. packet packaged lithium-ion batteries includes. Thus, an uninterrupted operation is ensured, even if the self-sufficient power generation unit for a short time, z. B. at night, can not generate electricity.

It can be provided, in particular, that the power supply of the liquid processing system is completely via the storage device for storing electrical current, which thus also acts as a buffer for fluctuating Stromerzeugungs- or current supply conditions.

The advantage of the liquid treatment plant according to the invention is the extended life due to the use of vibration sensors to detect the degree of soiling and vibrators to assist in cleaning or to increase the intervals between cleaning cycles. Thus, the plant is affected by a lower downtime compared to the prior art due to cleaning (eg backwashing). In addition, the liquid processing system can be fully decentralized if it has a self-contained power supply.

As a heat exchanger, a plate heat exchanger may be provided, comprising a plurality of mutually parallel plates, which are spaced from each other by means of sealing elements, wherein between the plates in alternation, respectively as frame profiles executed evaporator and condenser seals are introduced. By means of two end plates, which are connected by tie rods, the plates and the sealing elements can be compressed gas-tight, whereby a disassembly of the plate heat exchanger is made possible only by loosening the tie rods.

The control unit may be a Programmable Logic Controller (PLC).

The invention will be illustrated below with reference to an embodiment with reference to the accompanying figure, wherein the same or similar features are provided with the same reference numerals; Here, the single figure shows schematically a liquid processing system according to one embodiment.

The illustrated in the figure embodiment of the liquid treatment plant is a water treatment plant for the desalination of seawater. It includes the frame 2 on which the heat exchanger 3 in each case by means of the combined in the form of piezo elements devices 4 for detecting a vibration and facilities 5 are stored for vibrational excitation.

• Der Startverdampfer 3.1, in welchen die Rohflüssigkeit 1, hier Meerwasser, eingeleitet und mittels Wärme der externen Wärmequelle 8 teilweise verdampft wird.
• Der Multi-Effekt-Wärmeübertrager 3.2, der in diesem Beispiel in vier Stufen, den sog. „Effekten“, das aus dem Startverdampfer 3.1 eingeleitete und von diesem bereits erhitzte Wasser weiter reinigt, d. h. destilliert.
• Der nachgeschaltete Wärmeübertrager 3.3, der mit dem externen Kühlkreislauf 9 in Verbindung steht.

The heat exchanger 3 are in detail:

• The starter evaporator 3.1 , in which the raw liquid 1 , here seawater, introduced and by means of heat of the external heat source 8th partially evaporated.
• The multi-effect heat exchanger 3.2 , which in this example in four stages, the so-called "effects" that comes from the starting evaporator 3.1 initiated and further heated by this already heated water, ie distilled.
• The downstream heat exchanger 3.3 that with the external cooling circuit 9 communicates.

The distilled fresh water is in the water collection container 10 collected. The remaining brine is removed by means of the brine pump 12 in the brine tank 11 pumped.

The in the frame 2 placed control and regulation unit 6 includes the evaluation device 7 that the of the facilities 4 for recording a vibration detected vibrations of the heat exchanger 3 evaluated to make up for each of the heat exchangers 3 to determine a degree of pollution.

If the vibration analysis shows that the contamination limit has been exceeded, a cleaning cycle is started by using the detergent dispenser 13 an alcohol is introduced and the heat exchangers 3 by means of the facilities 5 be excited to vibrational excitation to forced vibrations.

During operation of the liquid treatment plant, the multi-effect heat exchanger becomes 3.2 not only to the cleaning cycles by means of the vibrators 5 stimulated to forced vibrations, but also to recurring periods of operation.

LIST OF REFERENCE NUMBERS

1

raw liquid

2

frame

3

Heat exchanger

3.1

start evaporator

3.2

Multi-effect heat exchanger

3.3

downstream heat exchanger

4

Device for detecting a vibration / vibration sensor

5

Device for vibration excitation / vibration generator

6

Control and regulation unit

7

evaluation

8th

heat source

9

Cooling circuit

10

Water collection tank

11

brine tank

12

brine pump

13

Of detergents

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007028129 B4 [0006]

Claims (11)

Method for operating a liquid treatment plant, wherein: by means of vibration sensors, the vibrations occurring during operation of the fluid treatment system are detected, the evaluated vibrations are evaluated with regard to a change in frequency and / or amplitude of predetermined vibration modes, if a cleaning cycle of the liquid treatment plant is triggered when a predetermined limit value of the change is exceeded, comprising: - Introducing a cleaning liquid in the liquid treatment plant a change in the operating pressure and / or the operating temperature, at least in individual components of the liquid treatment plant, and a stimulus for forced vibrations of at least individual components of the liquid treatment plant. Method according to Claim 1 , characterized in that the vibration sensors are also used to generate the forced vibrations. Method according to Claim 1 or 2 , characterized in that a frequency shift and / or amplitude change predetermined eigenmodes is determined, wherein when a predetermined limit value for the frequency shift and / or amplitude change of the eigenmodes is exceeded, a cleaning is initiated. Method according to one of the preceding claims, characterized in that the vibrations are detected at each heat exchanger with respect to the frame of the liquid treatment plant. Method according to one of the preceding claims, characterized in that evaporators of the liquid treatment system are excited outside the cleaning cycles to forced oscillations. Method according to one of the preceding claims, characterized in that an alcohol is used as a cleaning liquid, wherein after completion of the cleaning cycle by changing the operating temperature and / or the operating pressure of the alcohol is distilled off. Liquid processing plant, comprising: - at least one on a frame (2) mounted heat exchanger (3) for the evaporation of a crude liquid (1) and a control and regulation unit (6) with evaluation (7), characterized in that - at the at least one heat exchanger (3) means (4) for detecting a vibration of the heat exchanger (3) and means (5) for exciting the heat exchanger (3) are arranged for forced oscillations. Fluid treatment plant after Claim 7 , characterized in that the means (4) for detecting a vibration of the heat exchanger (3) are also the means (5) for exciting the heat exchanger (3) to forced oscillations. Liquid treatment plant according to one of Claims 7 to 8th , characterized in that the means (4) for detecting a vibration of the heat exchanger (3) and the means (5) for exciting the heat exchanger (3) to forced vibrations piezo elements. Liquid treatment plant according to one of Claims 7 to 9 , characterized in that each of the heat exchangers (3) by means of the means (4) for detecting a vibration and the means (5) for excitation to forced vibrations on the frame (2) is mounted. Liquid treatment plant according to one of Claims 7 to 10 , characterized in that the evaluation device (7) is arranged to determine a degree of contamination of the heat exchanger (3) on the basis of a deviation of vibration patterns detected during operation of the system with reference vibration patterns.

Images