Yu.V. Gornev ( General manager LLC "Vistaros")

It is well known that 60 to 75 percent of the energy consumption of sewer treatment facilities(KOS) cities and large industrial enterprises account for the supply of air to the aeration system. This article discusses the issues of possible energy savings in the aeration system through the use of energy-efficient elements of the system.

The reserves of energy consumption savings in the WWTP aeration system are enormous, they can be 70% or more. Let's consider the main elements of this system that significantly affect energy consumption. If we omit such issues as the need to maintain good working order of air supply pipelines, etc., then these include:

1. Presence of primary sedimentation tanks at WWTP, which allow to reduce Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of effluents at the inlet of aeration tanks. As a rule, primary sedimentation tanks are already present at most large WWTPs.
2. Introduction of the nitrification-denitrification process, which allows to increase the amount of dissolved oxygen in the return activated sludge. This process is increasingly being implemented in the construction and reconstruction of WWTP.
3. Timely maintenance and replacement of aerators.
4. The use of controlled blowers of optimal power, the introduction of a single control system for all blowers.
5. Application of specialized controlled valves in the air distribution system for aerotanks.
6. Introduction of a control system for each valve and all valves according to the data from the dissolved oxygen sensors installed in the aeration basins.
7. Use of air flow meters to stabilize the air distribution process and optimize the minimum dissolved oxygen setpoint for the valve control system.
8. Introduction to the control system of additional feedback on the ammonium sensor at the outlet of the aerotanks (used in certain cases).

The first two points (primary sedimentation tanks and the introduction of nitrification-denitrification) relate to a greater extent to the issues of capital construction at the WWTP and are not considered in detail in this article. The issues of the introduction of modern high-tech modules and systems that allow to achieve a significant reduction in electricity consumption at the WWTP are discussed below. These modules and systems can be implemented both in parallel with the solution of the first two points, and independently of them.

Blowers are the main consumers of electricity in the aeration air supply system. Their right choice is the basis for energy saving. Without this, all other elements of the system will not give the desired effect. However, we will not start with the blowers, but will follow the order in which all modules must be selected.

Aerators

One of the main characteristics of aerators is the specific efficiency of oxygen dissolution, measured as a percentage per meter of immersion depth of the aerators. For modern new aerators, this value is 6% or even 9%, for old aerators it can be 2% or less. The design of the aerators and the materials used determine their service life without loss of efficiency, which for modern systems ranges from 6 to 10 years or more. The choice of the design, number and location of aerators is carried out according to such parameters as the BOD and COD of effluents at the entrance to the aeration system, in terms of the volume of incoming effluents per unit of time and in the design of aeration tanks. If we are dealing with the reconstruction of WWTP with very old aerators in poor condition, then, in some cases, only replacing the aerators and installing blowers corresponding to the new aerators will reduce energy consumption by 60-70%!

Blowers

As mentioned above, blowers are the main energy saving element. All other elements reduce the need for air supply or reduce resistance air flow... But if you leave the old uncontrolled blower with low efficiency at the same time, there will be no savings. If several uncontrolled blowers are used at the aeration station, then, theoretically, by optimizing other elements of the system and achieving a decrease in the need for air supply, it is possible to take out of service and transfer to a reserve several blowers from among those previously used and, thus, reduce energy consumption. You can also try to compensate for the daily fluctuations in the oxygen demand of the aeration system by simply turning on or off the backup blower.

However, it is much more efficient to use a controlled blower, more precisely, a block of several controlled compressors. This allows you to provide air supply in exact accordance with the demand, which varies significantly during the day, and also changes depending on the season and other factors. The usual constant air supply by uncontrolled blowers is always excessive and leads to excessive consumption of electricity, and in some cases to disruption of the nitrification-denitrification process due to excess oxygen in the aerotanks. At the same time, the lack of air supply leads to an excess of the maximum permissible concentration (MPC) by pollutants in the effluent at the WWTP outlet, which is unacceptable.

Accurate air supply control with constant control of the level of dissolved oxygen in aeration tanks (and in some cases - and with constant automatic control of the concentration of ammonium and other pollutants in the effluent at the outlet from the aeration tanks) provides optimal level energy consumption with guaranteed compliance of treated effluents with existing standards.

The need for several blowers in the unit (for example, two large and two small) is due to the fact that the control range air compressor highly limited. It is in the range, at best, from 35% to 100% of the power, more often from 45% to 100%. Therefore, one controlled blower is far from always able to provide an optimal air supply, taking into account the daily and seasonal changes needs. Today, the most famous are three types of blowers: rotary, screw and turbo.

The choice of the required type of blower is made mainly according to the following parameters:

- the maximum and nominal air supply demand - depends on the parameters of the installed aerators, which, in turn, are selected based on their efficiency and on the demand of the entire aeration system in dissolved oxygen, as described above;

- the required maximum overpressure at the blower outlet - is determined by the maximum possible depth of the aeration pool drains, more precisely, by the depth of the aerators, as well as the pressure losses during the passage of air through the pipeline and through all system elements, such as valves, etc.

As a rule, each controlled blower has its own control unit, it is also important to have a common control unit for all blowers, which ensures their optimal operation. In most cases, control is carried out by the pressure at the outlet of the blower unit.

Controlled air valves

If in the system one blower (or a block of blowers) supplies air to only one aeration basin, then it is possible to work without air valves. But, as a rule, at aeration stations, a block of blowers supplies air for several aeration tanks. In this case, air valves are required at the inlet to each aeration tank to regulate the distribution of the air flow. Additionally, the valves can be used on pipes that distribute the air supply to different zones of one aeration tank. Previously, manually operated butterfly valves were used for these purposes. However, to effectively control the aeration system, it is necessary to use remotely controlled valves.

TO important characteristics controlled valves include:

1. Linearity of control characteristics, i.e. the degree of correspondence of the change in the position of the valve actuator (actuator) to the change in the air flow through the valve over the entire control range.
2. Accuracy and repeatability of the valve actuator working off the preset air flow setting. Determined by the quality of the valve (linearity of control characteristics), actuator and actuator control system.
3. Pressure drop across the valve in the working range of opening.

The pressure drop across butterfly valves during partial opening can be quite significant and reach 160-190 mbar, which leads to a large additional energy consumption.

If the system uses even the highest quality, but universal valves (designed for both water and air), then the pressure drop across such valves in the working range of opening (40-70%) is usually 60-90 mbar. A simple replacement of such a valve with a specialized VACOMASS elliptic air valve will lead to additional savings of at least 10% in electricity! This is due to the fact that the pressure drop across the VACOMASS elliptic in the entire operating range does not exceed 10-12 mbar. An even greater effect can be achieved when using VACOMASS jet valves for which the pressure drop in the operating range does not exceed 5-6 mbar.

Controlled dedicated air valves

VACOMASSfirmsBinder GmbH, Germany.

Often at the installation site of the controlled valve, the pipeline is made narrower to use the valve of the optimal standard size. Since the contraction and expansion is performed in the form of a venturi, this does not lead to any significant additional pressure drop across the valve section. At the same time, the smaller valve works in the optimal opening range, which ensures linear control and minimizes the pressure drop across the valve itself.

Dissolved oxygen sensors and valve control system

BA1 - aeration pool 1; BA2 - aeration pool 2;

PLC - program logic controller;

BV - block of blowers;

F - air flow meter; Р - pressure sensor;

O2 - dissolved oxygen sensor

M - drive (actuator) air valve

CPS - gate valve (valve) control system

SUV - blower control system

The figure shows the most common air control scheme for multiple aeration basins. The quality of wastewater treatment in aeration tanks is determined by the presence of the required amount of dissolved oxygen. Therefore, as a rule, the concentration of dissolved oxygen [mg / liter] is taken as the main controlled value. One or more dissolved oxygen sensors are installed in each aeration tank. The control system sets the setpoint (setpoint) of the oxygen concentration so that the minimum actual oxygen concentration is guaranteed to provide a low concentration harmful substances(for example, ammonium) in the effluent at the outlet of the aeration system - within the MPC. If the incoming volume of wastewater in a particular aeration tank decreases (or its BOD and COD decrease), then the demand for oxygen also decreases. Accordingly, the amount of dissolved oxygen in the aerotank becomes higher than the set point and, according to the signal from the oxygen sensor, the gate valve control system (CPS) reduces the opening of the corresponding air valve, which leads to a decrease in air supply to the aerotank. At the same time, this leads to an increase in the pressure P at the outlet of the blower unit. The signal from the pressure sensor goes to the Blower Control System (BCS), which reduces the air supply. As a result, the energy consumption of the blowers is reduced.

It should be noted that a well thought out optimal setting of a given minimum concentration of dissolved oxygen in the CPS is very important for solving the problem of energy saving.

Equally important is the correct and reasonable setting of the preset pressure P at the outlet of the blower unit.

Air flow meters

The main task of air flow meters in the aeration system from the point of view of energy saving is to stabilize the air supply process, which makes it possible to lower the set point of the dissolved oxygen concentration for the control system.

The system for supplying air from a block of blowers to several aeration tanks is quite complex from a control point of view. In her, as in any pneumatic system, there are mutual influence and delay in the processing of control actions and signals from feedback sensors. Therefore, the actual dissolved oxygen concentration constantly fluctuates around the setpoint (setpoint). Availability of air flow meters and common system control of all valves can significantly reduce the response time of the system and reduce fluctuations. This, in turn, allows you to lower the setpoint, without fear of exceeding the MPC of ammonium and other harmful substances in the effluent at the outlet of the WWTP. From the experience of Binder GmbH, the introduction of data from flow meters into the control system allows additional energy savings of about 10%.

In addition, if the process is underway at the WWTP phased reconstruction aeration systems, in which aerators, valves, valve control system and air flow meters are first installed while keeping the old blower, and then proceed to the selection of new controlled blowers, then the data on the actual air flow will help to produce optimal choice blowers, which leads to significant savings in their purchase and operation.

A distinctive feature of Binder GmbH VACOMASS flowmeters is their ability to operate on short straight sections "before" and "after" due to special technological solutions, as well as to be installed directly in the VACOMASS valve block.

Ammonium sensor

The ammonium concentration sensor can be installed in the channel at the outlet of effluents from the aeration tank system to control the quality of cleaning. In addition, the introduction of readings from the ammonium sensor into the control system allows additional stabilization of the system and additional energy savings due to further reduction of the dissolved oxygen concentration setpoint.

An example of the organization of a control system for air supply to aerotanks with feedback by the dissolved oxygen sensor (DO) and ammonium (NH4).

Fig. 8. Design of the blower module according to the "two-in-one" scheme.

Blower is a slang term rather than a technical one. It is more correct to call these machines blowers. However, given that this article is intended for a wide range of readers, we will use this term as more common. A blower, like any compressor machine, is characterized by two main parameters: capacity and generated overpressure.

In aeration processes, as a rule, aeration tanks with a depth of 1 to 7 m are used, which determines the range of excess pressures created by blowers: from 10 to 80 kPa. As for the blower performance, it depends on the volume of water processed by the installation: the larger the volume, the more air is needed. For example, the capabilities of treatment facilities of a small summer cottage village and a large city may differ by several orders of magnitude.

Accordingly, the range of required blower performance ranges from two to three cubic meters of air per hour to several tens of thousands. Of course, such a wide range of parameters corresponds to and wide range standard sizes of blowers - both in terms of power and dimensions. However, there are general requirements that are mandatory for all blowers that aerate water. First, the blower must be “dry”, that is, the supply air must be free of lubrication and wear products.

Secondly, the blower must be reliable, easy to operate and, if possible, not energy intensive, given its almost continuous operation around the clock. And thirdly, the blower must be quiet, because often works in close proximity to human housing. The last requirement is now especially relevant, since the construction of treatment facilities has acquired a trend of differentiation. In other words, the construction of numerous summer cottages, individual cottages, roadside cafes, etc. also implies the construction of small treatment facilities in close proximity to housing.

It is economically justified, since communications, construction and operation costs are sharply reduced. This trend has recently determined the demand for small-capacity blowers. Despite the great variety existing types compressor machines, it is difficult to choose a machine that meets all the listed requirements. The requirement for "dry" air supply, reliability and noiselessness sharply narrows this choice. In addition, the price of such compressors, as a rule, of imported ones, is high.

The range of compressors of this type offered by the domestic industry is extremely limited. For example, small sewage treatment plants require blowers with a discharge pressure of 20 to 80 kPa and a capacity of 5 to 1000 m3 / h. The requirement for the "dryness" of the supplied air in the specified range of parameters is mainly met by two types of blowers - volumetric action (membrane, spiral, rotary blowers) and dynamic action (turbo blowers).

Diaphragm blowers designed for a very small capacity (5-10 m3 / h). On Russian market they are supplied mainly by foreign companies, in particular by Japanese companies. The machines consume little electricity, are compact and quiet. The price of such blowers is from 500 to 1300 USD. The service life of these machines is determined by the quality of the main part - the membrane. According to the author, the operating time of this technique is 2-3 years. Attention to these machines has greatly increased, because they are used in individual cottage construction of treatment facilities.

Scroll compressors can still be attributed to the "exotic" in the market of "dry" compressors. This is a relatively new technique, which is being intensively mastered both here and abroad. The design of the machine implies the use of high technology in its manufacture, so the compressors are still very expensive. For example, the Swedish company Atlas Copco offers scroll compressors with a productivity from 10 to 24 m3 / h at a price of up to 6000 USD Level overpressure- up to 10 bar (100 mWC).

Practically, these machines, like reciprocating compressors without lubrication, have not yet found application in aeration systems.

Rotary blowers produces several firms from near and far abroad. The range of their capacities is from 30 to 3000 m3 / h. In practice, they are sometimes called gear, or type RUTs. A well-known domestic brand was the AF series blowers of the Melitopol Compressor Plant (Ukraine). Using Western technologies such blowers are now produced by Venibe (Lithuania). Several European companies supply such blowers to our market.

The design feature of rotary blowers is the presence of two synchronously rotating rotors. To synchronize the rotation, meshing and therefore lubricated gears are used. The presence of an assembly of synchronizing gears, naturally, reduces the reliability of the machine, increases the risk of oil entering the compression cavity through the shaft seal.

For the sake of fairness, it should be noted that due to the high technological level of production, the machines of European firms are highly reliable, however, their price is several times higher than those of Melitopol. For example, a blower of the AF series of the Melitopol plant for the most "running" parameters (pressure 50 kPa and productivity of 400 m3 / h) in our market costs 3000-4000 USD, while a blower of a European company similar in parameters is 8000-10000 USD. e. The difference in the resource of the compared equipment is corresponding.

In terms of reliability, of course, it is more preferable turbo blowers... The working element of the machine is a simple wheel with blades rotating in a housing on ball bearings. With the exception of bearings, the machine has no friction units, which determines its reliability. The advantage of turbo blowers should be attributed to the comparatively low level noise.

The main source of noise in all types of considered blowers is gas-dynamic noise, that is, the noise emitted by the air passing through the flow path of the machine. In rotary blowers, this noise is low frequency, because air is supplied "in portions", and in turbo blowers - high-frequency, because air is supplied continuously. High frequency noise is easier to damp. Suffice it to say that, despite the installation of mufflers, rotary blowers usually require separate rooms for themselves due to high level noise.

At the same time, turbomachines equipped with mufflers do not need such premises, because their noise level is close to sanitary standards. In fig. 1 shows the comparative noise characteristics of two blowers - rotary type AF series (curve 1) and vortex-type turbo blowers (curve 2). The curve corresponding to the PS-80 sanitary standards is highlighted separately. The figure shows that in most octave bands, the excess of sanitary standards for a rotary blower is higher than for a vortex blower.

Of course, this and subsequent benchmarking analyzes do not aim to criticize some machines in favor of others. The purpose of the analysis is to highlight the characteristic features of each type of machine, and the right to choose is given to the reader. In each case, the selection criteria may differ dramatically. Speaking of turbo blowers, one should immediately point out the range of their performance.

In the area of ​​relatively low capacities (from 10 to 3000 m3 / h), the turbomachines of the well-known traditional types(centrifugal, axial) are obtained, although compact, but very high-speed. The rotation frequency of, for example, a household vacuum cleaner reaches 16,000-20,000 min-1. The collector motor of such a vacuum cleaner is not capable of operating around the clock, as required by the operating conditions of treatment facilities.

It is possible to use a multiplier, i.e. transmissions with an overdrive ratio, for example, toothed or V-belt. Then the drive is possible from a conventional induction motor. However, in this case, the design becomes significantly more complicated, which means that reliability decreases. It is possible to use non-contact high-speed electric motors.

At present, the domestic industry has created and is producing prototypes of such units. For example, a centrifugal blower used in domestic ozonation plants is equipped with a multiplier, the high-speed shaft of which, with a blower impeller attached to it, rotates at a speed of over 50,000 min-1.

The toothed two-stage multiplier is oil lubricated. Another supercharger, developed and manufactured for pneumatic conveying systems, is made in the form of a cantilever mounted on the shaft of a high-speed electric motor of an impeller with blades. Working turnovers - over a hundred thousand. Special electric motor, special petal gas dynamic bearings, precision assembly and manufacture. There is no need to talk about the cost of such a unit - it is quite large. There is still no data on the operating time per resource.

With that said, the comparatively new type turbomachines - vortex... Due to the specificity of the air compression mechanism in the flow path of these machines, the range of their productivity and pressure is similar to the range of rotary machines. At the same time, vortex machines are free from the disadvantages of rotary ones: they have much higher reliability and are less noisy.

The rotational speed of vortex turbomachines is 3000-5000 min-1, which simplifies their drive. At the Moscow State Technical University. Bauman, a whole range of domestic vortex-type turbo blowers has been developed and is currently being serially produced by the industry. The designs are original and protected by patents in Russia, the USA and a number of European countries.

In terms of their characteristics, the machines are not inferior to the best foreign counterparts. Quite a wealth of experience has already been accumulated in the operation of such machines, including at treatment facilities. These are, first of all, machines of the EF-100 brand. The range of their capacities is from 200 to 800 m3 / h and pressures are up to 80 kPa. In fig. 2 shows a vortex blower from the EF-100 series. The machine is installed on the same frame with an electric motor and is connected to it by a V-belt transmission.

By selecting the pulleys and the power of the electric motor on practically one machine, a whole network is obtained different characteristics... In fig. 3 shows the performance characteristics of the EF-100 turbo blowers, sixteen standard sizes. Note that the characteristics are almost inversely proportional to the dependence of pressure on performance, which is very convenient for automation and control.

It is also important that, in contrast to the characteristics of centrifugal turbomachines, these characteristics do not have surging zones, i.e. in practice, the machine works steadily above the nominal pressure, while consuming only additional power. At the same time, the power consumption decreases with increasing productivity. The opposite is true for centrifugal turbomachines.

That is why vortex turbomachines are not afraid of starting modes. The selection of pulleys and electric motors, such as in the EF-100 series, is the easiest and cheapest way to obtain network performance on a single vortex machine. However, this is inconvenient from the point of view of regulation as a process of automatic parameter change. In aeration systems, the demand for air can vary significantly, both during the day (day and night) and depending on the season (summer, winter).

In order to save energy, and this saving can reach up to 40%, recently more and more systems are being used automatic regulation air supply by changing the rotational speed of the turbo blower. Thanks to the current frequency conversion devices on the market, the automatic control system has become simple and affordable.

In a vortex turbo blower, a change in the rotational speed shifts the characteristic in one direction or another, almost equidistantly to the initial one. In other words, the field of characteristics shown in Fig. 3, can be obtained practically on one machine by changing the rotational speed with a frequency converter. Such a machine has been developed. Vortex vacuum compressor VVK-3(Fig. 4) is made in the form of a monoblock, i.e. the impeller is mounted directly on the motor shaft.

Nominal parameters of the machine: productivity - 700 m3 / h, discharge pressure - 40 kPa, rotation speed - 3000 min-1. By lowering the speed with the help of a frequency converter connected to the power supply circuit of the electric motor, it is possible to obtain almost any operating point in the characteristic field shown in Fig. 3. VVK-3 is the largest machine in the VVK series of vortex blowers.

All machines in this series have common feature Are monoblocks. The first machine in this series - VVK-1 (Fig. 5) was developed at the Moscow State Technical University named after N.E. Bauman and has been serially produced at NPO Energia since 1991. The machine was intended for pneumatic conveying systems for flour in bakeries. Its working parameters:

• productivity - 120 m3 / h;
• pressure - 28-30 kPa;
• electric motor power - 5.5 kW;
• weight - 80 kg;
• dimensions - 500.500.500 mm.

In 1999, these machines began to be used in aeration systems. At present, a new version, VVK-2, has been created and is being serially produced by the domestic enterprise ENGA LLC (Fig. 6). Unlike its predecessor (VVK-1), VVK-2 introduced many design changes that increase reliability during round-the-clock operation. VVK-2 is a universal machine, because allows using a simple transformation to get two versions and, accordingly, two different characteristics with the following operating points (Table 1).

Taking into account the trend of expanding the construction of small treatment facilities, which was mentioned at the beginning of the article, at the Moscow State Technical University. N.E. Bauman, at present, prototypes of vortex-type microblowers with a capacity of 5 and 20 m3 / h with an electric motor power of 0.5 and 1.5 kW, respectively, have been developed and created.

Speaking of vortex-type turbo blowers, it would be unfair to keep silent about their main drawback - their relatively low efficiency. Its value does not usually exceed 35-40%. In fact, the energy consumption of vortex turbo blowers is 1.5-2 times higher than that of rotary ones. Therefore, when choosing the type of machine, especially in the case of its round-the-clock operation, this fact must also be taken into account.

However when it comes about micromachines of low power, power consumption is not the most main parameter... Reliability, ease of maintenance, low noise level are much more important, given that the treatment plant country cottage should work with little or no maintenance and close to housing. For more powerful machines, such as the VVK-3, savings are possible through regulation, as discussed above.

A few words about foreign counterparts... Siemens is one of the main manufacturers of vortex blowers in Europe. The company produces a whole range of machines of the ELMO-G series (fig. 7). Domestic vortex blowers are inferior to them only in design. In terms of technical parameters, they are not inferior in anything. As for the prices, of course, the difference is great.

For example, a domestic VVK-2 blower costs about $ 1,900, a Siemens 92H unit with a similar parameters costs about $ 4,800. If we talk about the range of productivity from three to several tens of thousands of cubic meters per hour, then there is no competition. turbo blowers traditional types, in particular, centrifugal.

Experts have known for a long time the TV series centrifugal blowers produced by the Chirchisk plant (Uzbekistan). Powerful stationary units with good efficiency and high reliability. At present, their production has been mastered by a Ukrainian enterprise - Lugansk Machine-Building Plant (VTs series blowers).

Like any stationary unit with a large mass (the weight of the blowers reaches several tons), the VC blower needs a good foundation. However, operating experience shows that it is not always possible to provide such a foundation. The soil on which the treatment plant is located is sometimes very unstable depending on the season.

At the Moscow State Technical University. N.E. Bauman, an attempt was made to create an alternative to the TV and VC series blowers. The developers took the path of creating a whole range of machines using such unification methods as sectioning and compounding, when derived units are obtained by a set of identical sections (modules).

Connecting these modules in series or in parallel determines either the total pressure or the total capacity. This technique allowed at a minimum technological costs get a wide range of units with different technical parameters... Each section (module) can be made in two versions: either it is a stage of a centrifugal machine, mounted on the same frame with an electric motor and kinematically connected with it by a belt drive, or it is two stages of a centrifugal machine, the impellers of which are respectively fixed at two ends of the electric motor shaft ( scheme "two in one").

The design of the module according to the "two in one" scheme is shown in Fig. 8. The impellers and bodies of the machines are made of welded steel sheet according to the original technology. Axial diffusers reduce the size of the module and have good anti-surge characteristics. By assembling the modules, you can get a wide range of machines.

Table Figures 2 and 3 show the main parameters of the modules and their possible combinations. Specified options are just an example and do not limit the number of possible combinations of modules. In addition to unification, the modular design has a number of advantages. Firstly, the small mass of the module (350-600 kg) does not require strong foundations.

Secondly, for the same reason, the modules can be placed arbitrarily on the available areas, connecting them only with a pipeline, which gives more options for the unit layouts. Thirdly, in the module, ordinary ball bearings with grease lubrication are used as shaft supports, which simplifies operation (there are no oil stations used in slide bearings, used, for example, in some modifications of TV blowers).

Fourthly, with the same power consumption as TV units, the modular unit does not create such powerful starting loads on the power grid, because step modules can be connected in series and do not have the usual reserve for TV units. installed capacity... Let's give an example to illustrate. In the blower VC 1-50 / 1.6 with parameters: V = 3000 m3 / h; .р = 60 kPa, an electric motor with a rated power of 160 kW is used.

At the same time, the same parameters can be obtained by three series-connected modules I (Table 2) with the total power of the electric motors: 30. 3 = 90 kW. And finally, fifthly, this is the price. She is also in favor of the modular version. For example, the same VC 1-50 / 1.6 blower costs about $ 17,000. , while the cost of three modules I is about $ 11,000.

Currently, at the Moscow State Technical University. N.E. Bauman, the development of new technology continues. Its customers are a number of domestic companies, in particular, those engaged in the installation of compact treatment facilities. Fast-growing security industry the environment and ensuring human life stimulates new technical developments in compressor construction.

In Russia, sewage treatment plants are one of the main consumers of electricity, most of which is spent on powering turbo blowers. Typically, multistage turbochargers are used to supply air for the treatment of domestic, storm and industrial effluents. But practice shows that it is more profitable to install easy-to-use industrial blowers that save up to 50% of electricity, and their purchase pays off in 3 years.

Such savings are achieved due to the fact that variable turbochargers supply air in the volumes required for biological wastewater treatment, depending on seasonal temperature changes. Moreover, the efficiency of such equipment is more than 80%. Note that the maintenance and repair of turbo blowers takes no more than 1% per year of the total cost of the units.

A distinctive feature of industrial blowers is the presence of adjustable suction and discharge guide vanes. The air regulation range is maximum (from 45 to 100%), while the efficiency is reduced by only 3-4%. There is blowing equipment with rotary vane mechanisms that allow you to adjust the amount of air masses supplied to the aeration tanks, so that you can adjust the degree of aeration.

Controlled industrial blowers have the following technical characteristics:

• productivity - from 1000 to 120,000 m3 / h;
• adjustment range - from 45 to 100%;
• power - from 34 to 3300 kW;
• Efficiency - from 88 to 92%.

Blower types

There are various types of industrial blowers that are installed in large sewage treatment plants and industrial plants. Let's consider each type separately.

Rotary blowers

These blowers use an oil-free method of compressing and supplying air. The principle of operation of such equipment is as follows: two three-toothed (three-band) rotors, which are located parallel to the motor, rotate in the housing in different sides, performing the function of a piston. Thus, the contactless running of the rotors does not require lubrication.

Rotary blowers

This equipment belongs to vertical air flow units. The blowers include a blower element with belt-driven three-tooth rotors, noise and suction mufflers, safety valves, compensator back dampers, two pressure gauges or filter clogging indicator. The swinging motor frame automatically tightens the belts to ensure effective work drive without special service personnel.

Centrifugal

According to the principle of operation, this equipment belongs to dynamically radial compressors. Air pressure and compression is created by the operation of impeller stages, accelerating the medium and then decelerating it with highly efficient diffusers with a large radius, while a certain pressure drop is created at the outlet.

Regulation of air supply in aerotechnics at treatment facilities is an opportunity to effectively save electrical energy.

The control object is technological process wastewater treatment using bacteria contained in activated sludge. Wastewater is fed to the aero section, where activated sludge with bacteria is located. To activate bacteria and mix the sludge mixture, air from a turbo blower is supplied to the section. Control over the content of dissolved oxygen in the aerobics is carried out by laboratory analysis, on the basis of which the air supply to the aerobics is regulated by the system shut-off valves in manual mode.

This system is complex in terms of requirements for control algorithms due to the influence of a large number of factors:

The amount of oxygen supplied;

Ambiguity in the behavior of the biological system of activated sludge;

Ambient temperatures;

The degree of concentration in wastewater of pollutants and other structures.

In general, the description similar systems does not fit into the traditional models of the theory of automatic regulation due to factors, the influence of which is almost impossible to predict. For example, air density and air compressibility are highly temperature dependent, and therefore the air control loops must be rebuilt depending on environmental conditions.

Continuous monitoring of the concentration of dissolved oxygen in aero tanks is a guarantee of high-quality cleaning and a reduction in energy consumption for blowers. The existing equipment at the enterprise (turbo blowers TV-175) and the method of laboratory measurement of the concentration of dissolved oxygen are obsolete and create a problem of high instability and excessive consumption of electrical energy.

To date, the most advanced is an automatic regulator in combination with an air blower for biological wastewater treatment and a continuous oxygen measurement system. The regulation of the performance of such installations is carried out by means of a diffuser guide vane with adjustable blades or an inlet guide vane with preliminary swirling of the flow, and a combination of the two mentioned systems is also possible. Continuous oxygen measurement system, which includes a primary converter with a sensor immersed in water, as well as a secondary converter using modern technology microprocessor-based signal processing, generates a signal in accordance with the concentration of dissolved oxygen, which enters the installation for air injection and then automatically changes the amount of air entering the aerobics.

In accordance with the methodology for calculating the specific air consumption per volume of incoming wastewater, the amount of air supplied to the aerobics was determined - 18030 m 3 / h.

Let's calculate the specific air consumption for the volume of incoming wastewater 28000 m 3 / day.

Specific air consumption

where: q 0 - specific oxygen consumption of air, per 1 mg of removed BOD - full.

For complete cleaning, BOD20 is assumed to be 1.1.

K 1 is the coefficient taking into account the type of aerothec, we take 2.0 for the first stage, 1.95 - for the second stage;

K 2 - coefficient depending on the immersion depth of the aerator:

2.08 = first stage;

2.92 - second stage

K t - coefficient taking into account the temperature of the waste water

K t = 1 + 0.02 (T w -20), where: T w is the average water temperature for summer period;

K 3 - coefficient of water quality, taken for urban wastewater 0.85.

C a - solubility of air oxygen in water, mg / l;

Tables of the dissolution of air oxygen in Lex water - BOD 20 of purified waste water, taking into account the decrease in BOD during primary settling. The data on BOD 20 were obtained from information on the qualitative composition of the normatively treated wastewater, by the testing laboratory of KZhUP "Unicom": BOD pol.post. 53.9 mg / l, BOD 5.1 mg / l.

K t = 1 + 0.02 (22.1-20) = 1.042

C a = 1 + C t, where: H is the immersion depth of the aerators, m;

C t is the solubility of oxygen in water. (Accepted according to table 27, Vasilenko. Water disposal. Course design).

Cal = 1 + 8.83 = 10.12

q airl = 1.1 = 18.75

q airll = 1.1 = 12.16

The daily air consumption according to the specific consumption is determined by the formula:

Q = q air + q average day , m 3 / day,

where: q air is the specific air flow rate;

q average day - the average daily consumption of wastewater entering the treatment, m 3 / day (28000 m 3 / day).

Q I = 18.75 14000 = 262500 m 3 / day

Q II = 12.16 14000 = 170 240 m 3 / day

Determine the hourly air consumption

Q 4 I = = 10938 m 3 / h

Q 4 II = = 7093 m 3 / h

The total consumption is

О р = Q 4 I + Q 4 II = 10938 + 7093 = 18031 m 3 / h

Thus, required amount air supplied to the aeroboks will be 18031 m 3 / h.

The following injection equipment is currently installed:

1.Turbo blower TV-175 with a capacity of 10,000 m 3 / h - 2 pcs.

2. turbo blower TV-80 with a capacity of 6000 m 3 / h - 2 pcs.

3. turbo blower TV-80 with a capacity of 4000 m 3 / h - 2 pcs.

To obtain the calculated specific air consumption, it is necessary to include at least two blowers: one TV-175 blower with an installed electric power of 250 kW and one TV-80 blower with an installed electric power of 160 kW at a rated load.

Taking into account the physical and moral deterioration of the pressure equipment operating since 1983, it is proposed to install a single-stage centrifugal compressor with a multi-blade open turbine impeller in combination with an air supply control system using linear servomotors with the following requirements and indicators technological equipment:

Initial data

To provide air supply in the amount of 12000 m 3 / h, it is necessary to turn on two TV-80 blowers with a total power of 320 kW.

Installed electric power operating technological equipment - 320 kW - at 12000 m 3 / h

The installed electrical capacity of the new technological equipment is 315 kW - at 16000 m 3 / h, and at 12000 m 3 / h - 249 kW.

We determine the annual savings in electrical energy when installing new equipment:

E e = (320 - 249) 0.75 24 365 10 -3 = 466 thousand kWh or 130.5 t of fuel equivalent

The cost of the saved fuel at a price of 1 ton of fuel equivalent = $ 210 (according to the Department of Energy Efficiency):

С = 130.5 × 210 = $ 27405 = 232942.5 thousand rubles.

Payback period of the event:

where K is the investment in the event, 2,000,000 thousand rubles;

C - savings from the implementation of the event, thousand rubles;

T = == 8.6 years.

Note: Clarification of all amounts of capital investments for the implementation of the proposed measures and the payback period is carried out after the development of design estimates

Blowers for sewage treatment plants are used for two technological processes:

• For aeration. The aeration process is the forced saturation of wastewater with air to stimulate the multiplication of aerobic bacteria. These beneficial bacteria break down the biomass in the water into methane and carbon dioxide. This process takes place at all large facilities in Russia. Depending on the volume of incoming wastewater, the intensity of aeration changes by regulating the performance of the blowers.
• Removal of biogas from decomposition by bacteria organic matter contained in waste water... Biogas, consisting of methane and carbon dioxide, is pumped out of tanks by a blower and delivered to the consumer.

To solve the set tasks, ZEPRIKON JSC offers two types of blowers for sewage treatment plants: rotary and screw. With their help, you will be able to solve all the tasks in the shortest possible time. Employees of our company can select blowers for sewage treatment plants directly from terms of reference clients.

Specifications

Modular design

In some cases, when the Customers do not have a separate room for the installation of blowers, our company offers to solve this problem by assembling the equipment in block containers. In this case, you get an autonomously operating compressor station for generating compressed air low pressure completely ready for operation. All systems are mounted inside the container. To start the station, you only need to supply electricity and bring the air supply network to the common collector.

How to order equipment

If you need a blower for sewage treatment plants, and you are ready to buy it, our company has the opportunity to supply it to you on favorable terms. JSC "ZEPRIKON" is a supplier of this equipment on the territory of the Russian Federation. Employees of our company will correctly select the required equipment for you, which will fully comply with your technical task. In addition, we are ready to carry out the installation, commissioning works and successfully put the equipment into operation on the territory of the Customer. Under an additional agreement, our service engineers will conduct an after-sales service maintenance compressors during the entire service life of the equipment.