Yu.V. Gornev (General Director of Vistaros LLC)

It is a fairly well-known fact that 60 to 75 percent of the energy consumption of sewage treatment plants (WWTP) in cities and large industrial enterprises falls on the supply of air to the aeration system. This article discusses the issues of possible energy savings in the aeration system due to 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 the Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) of effluents at the inlet of aeration tanks. As a rule, primary clarifiers 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 during the construction and reconstruction of the WWTP.
3. Timely maintenance and replacement of aerators.
4. Application of controlled blowers of optimal power, implementation 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 based on data from dissolved oxygen sensors installed in 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 discussed in detail in this article. The issues of introduction of modern high-tech modules and systems that allow to achieve a significant reduction in electricity consumption at 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. The 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 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 a 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 the resistance to 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 plant, then, theoretically, by optimizing other elements of the system and achieving a decrease in the need for air supply, several blowers from the previously used ones can be taken out of service and transferred to a reserve, 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 supply of air 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 the aerotanks (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 aerotanks) provides an optimal level of energy consumption with guaranteed compliance of the treated effluent with existing standards.

The need for several blowers in a block (for example, two large and two small) is due to the fact that the control range of an air compressor is very limited. It is in the range, at best, from 35% to 100% of 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 daily and seasonal changes in demand. 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 for 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 based on 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 blower unit 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.

Important characteristics of 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. The error and repeatability of the valve actuator working off the setpoint for the air flow. 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 large additional energy costs.

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 operating 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

VACOMASS firmsBinder GmbH, Germany.

Often at the installation site of the controlled valve, the pipeline is narrowed to use the valve of the optimal size. Since the contraction and expansion is performed in the form of a venturi, this does not lead to any significant additional pressure drop in the valve section. At the same time, the smaller valve operates 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 - air valve drive (actuator)

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. In the control system, the setpoint (set average value) of the oxygen concentration is set so that the minimum actual oxygen concentration is guaranteed to provide a low concentration of 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 oxygen demand 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 allows 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 it, as in any pneumatic system, there are mutual influences and delays in the processing of control actions and signals from feedback sensors. Therefore, the actual dissolved oxygen concentration constantly fluctuates around the setpoint (setpoint). The presence of air flow meters and a common control system for 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 WWTP outlet. Based on 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 WWTP is undergoing a stage-by-stage reconstruction of the aeration system, in which first aerators, valves, valve control system and air flow meters are 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 the optimal choice of 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 effluent 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 a further decrease in the dissolved oxygen concentration setpoint.

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

Air Blowers for Aeration in Wastewater Treatment

Keywords:biological treatment, air blowers, aeration

Biological treatment today is one of the most environment-friendly methods of treatment of industrial and municipal wastewater. Saturation of the treated water with oxygen is a mandatory condition for an efficient aerobic biological treatment process. This is achieved with air blowers designed for compression and delivery of air, and for creation of vacuum.

Description:

Aeration blowers for wastewater treatment

Biological treatment is currently one of the most environmentally friendly methods of water treatment for both industrial and domestic wastewater. For the effective course of the process of aerobic biological treatment, a prerequisite is the saturation of the treated waters with oxygen. For this, blowers are used to compress and pressurize air, as well as to create a vacuum.

When choosing equipment for sewage treatment plants, blowers are given special attention. The air flow required for wastewater treatment depends on the oxygen demand of the process, the required removal efficiency of contaminants, and the treatment technology used. The required amount of supplied air when cleaning in aerotanks depends on the composition and temperature of wastewater, geometric characteristics of aerotanks, and the type of aerators used.

The design working pressure that the blowers must create should be taken based on the depth of the aerators in the aerators and the pressure losses in the air supply network and the aerators themselves.

The range of required blower performance, depending on the specified conditions, can vary significantly and range from several cubic meters of air to tens of thousands. At the same time, regardless of the size, blowers used for wastewater aeration must meet the following requirements.

1. Aeration is one of the most energy-consuming processes. Up to 70% of the energy in wastewater treatment plants is consumed by aeration systems. Accordingly, one of the most important requirements is the high energy efficiency of the blowers used. According to the requirements of regulatory documents, it is necessary to consider the possibility of utilizing compressed air heat for the needs of a wastewater treatment plant. It is recommended to use blowing equipment that allows control of the flow rate of the supplied air. This is due to the daily and seasonal irregularities in the inflow of wastewater, as well as to changes in both the temperature of the wastewater and the temperature of the air supplied to the blowers. When using technologies for biological removal of nitrogen and phosphorus, it is recommended to provide for flexible or stepwise control of the air supply system to aeration tanks using automation equipment.

2. Blowers should have a minimum impact on the ecology of the environment. The cleanliness class of compressed air is regulated in accordance with GOST R ISO 8573–1–2016 “Compressed air. Part 1. Contamination and cleanliness classes ", which is identical to the international standard ISO 8573-1: 2010 *" Compressed air. Part 1. Contamination and cleanliness classes ”(ISO 8573-1: 2010). Oil-free blowers are currently recommended. The absence of oil has a beneficial effect on the maintenance of the vital activity of bacteria and microorganisms when treating sewage sludge, the air of which does not contain oil particles. The air content is especially unacceptable if the water after cleaning has to be reused.

3. The blower should work as quietly as possible, since the increased noise level negatively affects the personnel operating the equipment of the treatment facilities.

4. The blower must be designed for the operating conditions, that is, it must be resistant to corrosion, temperature extremes and atmospheric precipitation.

5. Blowers should be easy to operate.

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

Blower is a slang term rather than a technical one. It is more correct to call these machines superchargers. 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 a wide range of standard sizes of blowers - both in power and in size. However, there are general requirements that are mandatory for all blowers that aerate water. Firstly, the blower must be “dry”, that is, the supplied air must be free of lubrication and wear products.

Secondly, the blower should 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 latter requirement is now especially relevant, since the construction of wastewater treatment plants 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 wide variety of existing types of compressor machines, it is difficult to choose a machine that meets all of the listed requirements. The requirement for "dry" air supply, reliability and noiselessness sharply narrows this choice. In addition, the price of such compressors, usually imported, is high.

The range of compressors of this type offered by the domestic industry is extremely limited. For example, small wastewater 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). They are supplied to the Russian market mainly by foreign firms, in particular Japanese ones. 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 increased greatly, 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 capacity of 10 to 24 m3 / h at a price of up to 6000 USD. Overpressure level - up to 10 bar (100 mWC).

In practice, these machines, like dry piston compressors, 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). With the use of 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 capacity 400 m3 / h) in our market costs 3000-4000 USD, while a blower of a European company similar in parameters is 8000-100000 USD. e. The difference in the resource of the compared equipment is corresponding.

In terms of reliability, of course, 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 is the relatively low noise level.

The main source of noise in all types of considered blowers is gas-dynamic noise, that is, the noise emitted by air when 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 the high noise level.

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 comparative noise characteristics of two blowers - a rotary type of the AF series (curve 1) and a vortex-type turbo blower (curve 2). The curve corresponding to the PS-80 sanitary standards is highlighted separately. It can be seen from the figure 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 comparative 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 specific 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 \u200b\u200bcomparatively low capacities (from 10 to 3000 m3 / h), turbomachines of 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. transmission with an overdrive ratio, for example, toothed or V-belt. Then the drive is possible from a conventional asynchronous electric motor. However, in this case, the design becomes significantly more complicated, which means that reliability decreases. The use of non-contact high-speed electric motors is possible.

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 blower, 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 the 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 this in mind, a relatively new type of turbomachine is of great interest - 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.

By 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. First of all, these are EF-100 cars. 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 of different characteristics is obtained. 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 operates steadily above the rated pressure, while consuming only additional power. In this case, the power consumption decreases with increasing productivity. With centrifugal turbomachines, the opposite is true.

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 simplest 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 electricity, and this savings can reach up to 40%, recently, systems for automatic control of air supply by changing the rotational speed of a turbo blower have been increasingly used. 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 using 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 rotational speed using 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 of this series have a common feature - they 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 mass-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 were used in aeration systems. At present, a new version, VVK-2, has been created and is being mass-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 obtain 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 sewage treatment plants, 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 to low-power micromachines, energy consumption is not the most important parameter. Reliability, ease of maintenance, low noise level are much more important, given that the treatment plant of a country cottage should operate practically without maintenance and close to housing. For more powerful machines, such as the VVK-3, savings are possible with the help of regulation, as discussed above.

A few words about foreign analogues. 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 prices, of course, the difference is great.

For example, a domestic VVK-2 blower costs about $ 1900, a Siemens 92H unit with a similar parameters costs about $ 4800. If we talk about the productivity range 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 long known 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 soils on which the treatment facilities are located are 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 VTs series blowers. The developers took the path of creating a whole range of machines using such unification methods as sectioning and compounding, when the 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 made it possible to obtain a wide range of units with various technical parameters with a minimum of technological costs. 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 on 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 sheet steel according to the original technology. Axial-type 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. These options are only an example and do not limit the number of possible combinations of modules. In addition to unification, the modular design has several 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 layout. Thirdly, the module uses conventional grease-lubricated ball bearings as shaft supports, which simplifies operation (there are no oil stations used in slide bearings, used, for example, in some modifications of TV blowers).

Fourth, 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 power reserve for TV units. Let's give an example for illustration. In the blower VC 1-50 / 1.6 with parameters: V \u003d 3000 m3 / h; .р \u003d 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 electric motors: 30. 3 \u003d 90 kW. And finally, fifthly, this is the price. She also favors 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 firms, in particular, those engaged in the installation of compact treatment facilities. The rapidly developing industry of environmental protection and ensuring human life stimulates new technical developments in compressor construction.

Low pressure blowers or compressors are widely used in the chemical, metallurgical, food and mining industries, as well as in wastewater aeration, building materials and railways.
The company "Spetsstroymashina" produces blowers of the BP series (rotary blowers), based on blowers from the world's best manufacturers, such as Tuthill
Vacuum & Blower Systems (USA); Dresser Roots (USA, England), Aerzener Maschinenfabrik GmbH (Germany). All used blowers are ISO 9001 certified. Blowers of the BP series manufactured by Spetsstroymashina have high efficiency, are reliable and trouble-free in operation over a long service life.

When working with the Customer, the engineers of our company carefully and scrupulously study and analyze the received technical information and offer high quality equipment at an optimal price.

The use of high-quality imported blowers with low noise characteristics makes it possible to use BP series blowers directly in production facilities. For additional protection against the effects of noise radiation, Spetsstroymashina manufactures and delivers, complete with BP series blowers, noise protection covers of two modifications ShK SSM and ShK Stribog SSM with an integrated control cabinet for the ShUV CCM blower.

Shumkozhuh ShK SSM is designed in such a way that the opening of the minimum number of panels allows to provide the best service of the units and mechanisms of the blower.

The design of BP blowers allows easy and unimpeded access to the main components that are subject to periodic replacement or maintenance: belts, filler plugs of the blower, electric motor switch box, removable air filter cover, etc.

The BP series blowers are equipped with vibration mountings. There is a possibility of simple and quick installation of vibration dampers on the concrete foundation of a production facility.

To automate the operation of the equipment, Spetsstroymashina manufactures various control cabinets for blowers SHUV ZT SSM (star-delta), SHUV PlP SSM (control cabinet for a blower with a soft start), SHUV PR CCM (control cabinet for a blower with a frequency drive), etc. using accessories such well-known world manufacturers as Siemens, Danfos, Mitsubishi, etc.

Through the efforts of the designers of the Spetsstroymashina company, it was possible to design BP series blowers that harmoniously combine quality, compactness and the ability to install drive motors of different companies on one base.

The mass-dimensional characteristics of the BP series blowers are comparable with their foreign counterparts. When installing BP series blowers, significant production space is saved and the convenience of equipment maintenance increases.

If the Customer does not have premises for the installation of equipment, Spetsstroymashina manufactures and installs blowers in a block of containers of the “Sever” type with varying degrees of automation, as well as carries out service and commissioning works.

Blowers manufactured by Spetsstroymashina undergo strict quality control and mandatory certification, which allows our products to compete with many global manufacturers of low pressure compressors, such as GE Roots, Vienybe, LUTOS, Robuschi, Kaeser Compressors, Hibon, Atlas Copco, Aerzener.

Aeration of wastewater - saturation of the liquid with oxygen, giving life to bacteria that process toxins, organic matter, forming sludge. Bubble streams are created by diffusers installed at the bottom of the treatment reservoir.

Large volumes of compressed air are required for continuous operation of the equipment, which can be provided by blowers for aeration.

equipment requirements

Compressors for sewage treatment plants are selected based on the following conditions:

1. The first thing to consider when choosing a compressor is the depth of the reservoir. A pressure of 1 bar is generated every 10 m of the liquid column. Accordingly, a blower for a sewage treatment plant must create a working pressure sufficient to pump air to the bottom level. As a rule, the depth of treatment facilities does not exceed 7 meters (0.7 bar - 70 kPa), thus, most models of centrifugal and VRMT blowers manufactured by Thermomechanics LLC are suitable for aeration.
2. Performance, which is calculated based on the size of the reservoir, the number and characteristics of diffusers. The volume of required air can be from 100 to 50 thousand cubic meters per hour.
3. "purity". The air must be free of lubricating coolants that would adversely affect the vital functions of bacteria.
4. Simplicity and reliability. The low pressure compressor will have to run non-stop. For aeration of water, machines with direct drive from the motor shaft, without gearboxes and V-belt drives are suitable. Centrifugal blowers of the Tremomechanika plant have a resource of more than 100 thousand hours of continuous operation.
5. Low noise. Small sewage treatment plants serving the villages of private households and commercial enterprises are becoming more widespread. Proximity to housing, excludes the use of equipment exceeding sanitary standards in terms of noise. The acoustic indicators of vortex and centrifugal blowers of Thermomechanics are in the range of 50-75 dB, which fully complies with the requirements of SanPiN.
6. Profitability. Energy consumption directly depends on the efficiency and power of the blower motor. Rotary blowers for aeration have a higher efficiency, however, "voracious" vortex blowers have an advantage in noise, reliability and purity of the injected air

In order not to overpay for electricity, you need an accurate calculation of a sufficient amount of air per unit of time, knowing which, a blower of a certain capacity is selected.

The use of automatic control systems also allows you to reduce the operating time of the engine, and, accordingly, the electricity bills.

How to choose

To buy the optimal type and model of blower, to minimize the cost of aeration of waste water, call the sales department of the Thermomechanics plant, or order a call back at a convenient time.

The service engineer will carry out preliminary calculations of the air flow, suggest the most suitable equipment for the specific situation.

Product prices are announced at the request of the client, after agreeing on the blower model, or technical specifications for the design of the installation.