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since 1997
"INTECH GmbH"
We are interested in cooperation with the manufacturers of centrifuges, who are looking for an official and reliable distributor to deal with supply & delivery of their equipment to the industrial plants in Russia.
The company’s top management and sales team are well acquainted with the Russian market, its mentality and laws; they also understand industrial specifics of the financial and economic activities of the Russian customers. All our sales managers have a large customer database, extensive experience of successful sales and well-established connections with the potential buyers of your centrifuges. This allows our managers to promptly set out the most promising directions for promotion and to ensure a rapid entry of the products into the promising Russian market. Our employees, who are fluent in English and German, are focused on working at the international market with the supplies of foreign equipment.
Our team of experienced engineers, who can handle the most serious technical problems, constantly keeps in touch with the Russian customers, holds meetings and delivers presentations regarding the latest achievements of our manufacturing partners. They point out the engineering challenges and actively communicate with all the departments at Russian plants. That is why the specifics of doing a business in the Russian Federation are well-known to us, and we also know the equipment of the local industrial plants and their up-to-date modernization needs.
Once we become your authorized representative in Russia, our marketing staff will carry out a market research in order to check the demand for centrifuges, will submit a market overview for centrifuges that you offer and evaluate the needs for this type of equipment at local plants. Our specialists will also estimate the potential and capacity of this market at local industrial plants. Our IT-team will start developing a website for your products in Russian. Our experts will assess the conformity between your centrifuges and customer needs as well as analyze the common reaction to the new goods in general. We will look into the categories of potential customers, and pick out the largest and the most promising plants.
Upon becoming your authorized agent on the territory of Russia, ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), will obtain certificates, if required, for a batch of the goods, for various types of centrifuges in compliance with Russian standards. We can also arrange the inspection in order to obtain TR TS 010 and TR TS 012 Certificates. These certificates provides permission to operate your equipment at all industrial plants of the EAEU countries (Russia, Kazakhstan, Belarus, Armenia, Kyrgyzstan), including the hazardous industrial facilities. Our company is eager to assist in issuing Technical Passports for centrifuges as per Russian and other EAEU countries’ requirements.
Our engineering company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), collaborates with several Russian design institutes in various industrial segments, which allows us to conduct preliminary design as well as subsequent design works according to the standards, construction rules and regulations that are applicable in Russia and other CIS countries. It also enables us to include your centrifuges into the future projects.
The Company has its own logistics department that can provide packing service, handling as well as the most efficient and cost effective mode of transportation of the goods (incl. over dimensional and overweight goods). The goods can be delivered on DAP or DDP-customer’s warehouse basis in full compliance with all the relevant regulations and requirements that are applicable on the Russian market.
Our company has its own certified specialists who will carry out installation supervision and commissioning of the delivered equipment, as well as further guarantee and post-guarantee maintenance of centrifuges. They will also provide necessary training and guidance for the customer’s personnel.
There are two main types of centrifuges: settling centrifuges and filtration centrifuges. Settling centrifuges are used for separation of emulsions and suspensions by settling of dispersed particles under the influence of centrifugal forces. Filtration centrifuges are also widely used in the chemical industry.
Classification of centrifuges is generally produced according to the following parameters:
Centrifuges are divided into two groups by a centrifugal separation factor and they are called normal centrifuges (Kp <300) and high-speed centrifuges (Kp> 3000).
Normal centrifuges are most commonly used for separation of all suspensions, except those having a very small concentration of solids. High-speed centrifuges are used to separate fine suspensions and emulsions.
If dividing centrifuges by their purpose, we can distinguish settling centrifuges, filtration centrifuges and centrifugal separators.
In addition to the above, centrifuges are divided by the method of cake discharge. The cake can be discharged manually using reciprocally moving knives and blades or by gravity or centrifugal force.
Centrifuges can also be divided by the device supports, based on which, centrifuges are divided into suspended and standing ones, and they are divided into vertical, horizontal and inclined ones by location of axis.
These devices are divided into continuous and discontinuous ones by the process of organization of centrifugation.
Discontinuous centrifuges have three main operating periods:
Charging of the drum is performed when an empty drum rotates at a certain speed which is less than the operating speed or in the case when the full rotational speed is reached. In some cases, the drum must be charged before the start of the centrifuge. Discharging of the cake takes place after the centrifuge stopping, or when the drum is rotated at a low speed.
Quite often, after the main process of centrifugation is completed, it becomes necessary to wash the cake. To do this, washing water is pressed, which is produced by the additional start-up of the centrifuge drum. In some cases, certain components must be also washed out of the initial mixture.
A perforated or a nonperforated drum is periodically used in discontinuous centrifuges.
At that the drum is encased in the body, which serves for collection of filtrate or washing liquid, as well as the safety guard in the event of a failure or destruction of the drum. Rotation of the drum is produced by the electric motor.
Due to centrifugal forces action the liquid is pushed through the filter material and holes in the drum. The liquid is collected in the body and then discharged via the pipeline.
If it is necessary to obtain the cake, containing a minimum amount of moisture, the perforated drums are used. With their help, it is possible to achieve the ultimate cake humidity of about 1-5% (in the case of a very fine-cut solid phase it can reach up to 40%). When using nonperforated drums for the purpose, the cake will contain significantly more moisture (about 70% and more).
To increase separation efficiency, special ring insertions are installed into nonperforated drums, reducing movement velocity of liquid located near the walls. Thus, process of solid particles settling is greatly improved.
Discontinuous centrifuges are usually produced with a vertical shaft. Discharging of material in these centrifuges can be bottom or top. Bottom discharge is considered to be more convenient, but it is high-manual-labor consuming. To facilitate discharging, the devices are equipped often enough with easily controlled mechanical shovel. Some centrifuges of this type are produces as self-discharging ones.
There appear unsafe and relatively strong vibrations of the drum in the case of uneven distribution of the material, subject to be treated, in the standing centrifuges, fitted with a vertical shaft and a rigid support. Because of this, modern centrifuges are equipped with elastic supports, at that thrust bearing of the shaft is mounted in a spherical bushing.
Centrifuges suspended from three columns and centrifuges with top support are the most common discontinuous centrifuges.
Classification of centrifuges:
| Type | Mode of operation | Method of cake discharge | |
|---|---|---|---|
| Normal centrifuges (∅<3500) | Filtration centrifuges | Discontinuous | Hand |
| Gravity | |||
| Knife | |||
| Continuous | Nozzle | ||
| Pusher-type | |||
| Conveyor | |||
| Settling centrifuges | Discontinuous | Hand | |
| Knife | |||
| Centrifugal | |||
| Continuous | Conveyor | ||
| High-speed centrifuges (∅>3500) | Tubular bowl centrifuges | Discontinuous | Hand |
| Separators | Discontinuous | Hand | |
| Continuous | Hydraulic |
Design of simple settling centrifuge is shown in the following figure:
A drum fitted onto the rotating shaft is the main part of the centrifuge. Solid particles of suspension are thrown onto the drum walls by centrifugal force action. When consolidating, these particles form the cake. Clarified liquid flows into a static body and is discharged through the nozzle in its bottom. After ending of centrifuge operation the cake is discharged manually.
Drawing of a continuous horizontal settling centrifuge with a conveyor discharge:
The principle of operation of this centrifuge is that the suspension is supplied through a pipe into the internal drum, and then it is discharged through the holes into a settling drum. At this stage a separation of the suspension occurs. Clarified liquid is supplied into the body and it is discharged through a nozzle. The screw conveyor transports the cake and discharges it through the nozzle.
Separation of fine suspensions and emulsions requires significant centrifugal forces. High-speed centrifuges of two types are used for such processes:
Tubular-bowl high-speed centrifuge is equipped with nonperforated bowl having a shape of a small-diameter pipe (up to 240 mm). Bowl length is several times greater than its diameter, which can significantly increase the rotational speed of the bowl and generate a strong centrifugal force. In addition, suspension path is extended in this type of bowl, which improves the settling process. Substance is supplied into the rotating bowl in tubular-bowl high-speed centrifuges. The substance moves through the pipe, collides against the baffle and is thrown to the walls of rotating bowl. Long cross lag prevents the cake from coming off the walls. The bowl has nozzles and chambers for an individual discharging of heavy and light liquids. A bowl of this type of centrifuge is fixed to a flexible shaft. Tubular-bowl high-speed centrifuges are also equipped with interchangeable diaphragm ring.
These are the advantages of such devices:
High-speed centrifuges are characterized by increased rotational speed due to reduced radius of rotation.
Drawing of discontinuous tubular-bowl high-speed centrifuge:
A rotor with nonperforated walls is rotating in the body. Radial blades are located inside the rotor, preventing liquid from coming off the walls of the bowl during rotation. The bowl is driven by a pulley. Thrust bearing is located at the bottom of the centrifuge, through which a pipe is brought into the bowl for suspension supplying. The solid phase is settled on the walls of the rotor and the liquid phase is discharged through the upper outlet. The cake is discharged manually. Since the operating volume of these devices is small, they are mainly used for separation of suspensions with low content of solid phase (no more than 1%).
Filtration centrifuge is a device for suspensions separation using centrifugal force. A rotating drum, the inner surface of which is covered with filter material, is the main component of the device.
When the drum rotates, centrifugal force influences the suspension. As a result, the filtrate passes through the membrane, and solid particles are settled on its surface. Pressure difference, occurring at this on both sides of the filter membrane is significantly higher than that one in filters. This allows to use a filtration centrifuge for separation of suspensions with nondeformable particles, forming little compressible cakes. Humidity of cake is from 0.5 to 5%, and it decreases with increasing size of solid particles. Cake obtained in conventional filters has a higher moisture content.
Stages of suspensions separation in a filtration centrifuge:
If necessary, the cake may be washed with liquid. Moisture content in the dried cake is less than the volume of its pores. In practice, the volume of solid phase in separated suspensions is 5-25% in the case of amount of solids of 10-1000 µm or more.
Filtration centrifuges differ both by design and by the type of operations control. Depending on the method of filtration operations conducting, the devices are divided into discontinuous and continuous ones.
Pendular centrifuges are discontinuous devices. Discharge of cake is produced by hand and can be both top and bottom one. Suspensions of low to medium concentration are supplied into a centrifuge in the process of operation. Suspensions with a high content of solid particles are supplied into a motionless centrifuge. The filtrate is discharged through the bottom nozzles of the body.
After the suspension is separated, the motor is switched off and the drum stops. The operator discharges the cake manually through the bottom (in the case of centrifuges with bottom discharge) or across the wall (in the case of centrifuges with top discharge).
Simplicity of design and relatively low cost of equipment represent the advantages of pendular centrifuge.
Drum diameter of pendular centrifuges is 400-1250 mm in case of centrifuges with top discharge or 800-1600 mm in case of centrifuges with bottom discharge.
Centrifuge with mechanized bottom discharge of the cake is a more complex discontinuous device than a centrifuge with a hand discharge. All the operations, including suspension charging, filtration, washing, pressing and cake separation, are carried out automatically.
When suspension enters the drum, its circumferential speed is of 8-30 m/s. During washing and pressing of the cake, circumferential speed of the drum is 50-75 m/s. Due to the fact that different drum speed is required for various operations performing, the centrifuge is equipped with a motor to vary the output rotational speed.
The cake is discharged using a wide knife, the length of which is equal to the height of the drum. The knife rotates about a vertical axis and comes closer to the surface of filter material during the cake layer cutting. When cake discharging, circumferential drum speed is 4-5 m/s, which is provided by an individual motor. Knife can be operated both manually and automatically.
Filtration centrifuge drum diameters can be in the range of 1000-1600 mm.
Centrifuges of the considered type are most effective for separation of suspensions, having solid particles with the size of 30 µm, occupying more than 10% volume of composition.
A self-centering filter drum and protection against centrate ingress to the drive and support is a distinctive feature of the suspended centrifuge.
In suspended centrifuge the shaft is suspended at the top end from the ball support. Rubber bumper is attached nearby, keeping the shaft from deviation from the vertical plane. A system of bearings located in the cage serves as a support. This cage, in its turn, rests on a drive head body. Drum self-centering is achieved by such an arrangement.
The cake can be discharged in two ways: manually (it is necessary to stop the rotor to do so) or automatically (when the rotor rotates at a low speed). When using mechanized discharge, the piston, moving across the total drum height, pushes cake through the circular hatch. Cone-like cover is attached to the piston. It descends for the time of cake discharge, then goes up and closes the bottom outlet of the drum.
Each operation is performed when the rotor rotates at a certain speed. For these purposes, there is a five-speed motor in the centrifuge.
A horizontal centrifuge with a knife discharge of cake is used for the separation of suspensions, where solid particles content exceeds 10% and has dimensions of up to 30 µm (grinding of them is allowed).
Automatic performing of all operations from the suspension charging to cake discharging is a distinctive feature of this centrifuge. At that, the drum is rotated at a constant speed.
Operating cycle time is approximately 10 minutes. There is a program with a certain period of time for each operation.
Process scheme can be represented as follows. The pipeline valve opens for 3 minutes and the suspension is charged. After the filtrate is separated from the solid phase, the cake is pressed for 0.5 minutes. Next, washing liquid is supplied for 1 minute. The next pressing operation is also carried out for 0.5 minutes. After that, the knife is switched on for 5 minutes, it cuts off the cake, gradually approaching the filter membrane.
The valves are opened and closed automatically by means of the pistons, moving in the cylinders. The valve is mounted on the rod end, and it opens when the piston moves upwards, and it is closed when the piston moves downwards. Oil is injected to move the piston in the cylinder. Similarly, the knife is driven to remove the cake. Cut layers are discharged through an inclined vibrating chute.
Centrifuges of the considered type are equipped with cantilever rotor (cylinder has a diameter of up to 2000 mm) or a rotor, located between two supports (cylinder has a diameter of up to 3400 mm).
Pusher-type centrifuge is used for separation of suspensions, containing more than 20% of solid particles, having size from 0.1 mm. These devices are single-stage continuous units. They are most effective, when used for suspensions, which can be easily separated and quickly lose their fluidity.
Rotor of the centrifuge consists of a bottom and a shell, where slotted screen is installed. There is a pusher inside the rotor, it can be represented by a piston or a movable bottom. During operation, the pusher produces rotational and reciprocating movement.
Suspension is supplied continuously through a hopper to the slotted screen. Centrate percolates through the screen and cake moves forward by means of the pusher, being washed by washing liquid at the same time, afterwards it is pressed and discharged in batches into the receiving tank.
At the moment when the pusher moves forward, a small portion of suspension reaches the cleaned screen, because of which solid particles can percolate together with the centrate. To prevent ingress of cake into the centrate, the screen, openings of which do not exceed solid particles of suspension in size, is installed in drum.
It is impossible to clean the screen mechanically. This characteristic is a distinctive feature of this type of centrifuge. Therefore, the device is suitable for separation of suspensions, having soluble solids. In such cases, a screen is regenerated by washing with a liquid, capable of cake dissolving.
The centrifuge rotor has a diameter of 160-1400 mm. Its length depends on the properties and thickness of the cake.
Continuous filtration pusher-type centrifuge is shown in the following diagram:
Drawing of filtration pusher-type centrifuge. Principle of operation
In this centrifuge the suspension enters the centrifuge cone hopper, rotating at the same frequency, as the perforated drum. Due to the fact that the suspension starts a rotary motion, it is discharged through the holes in the hopper at filter membrane into the area in front of the piston. Due to centrifugal force, the liquid phase moves through the filter membrane and perforated drum into the body. After this it is discharged through a nozzle, located in the bottom part of the body. The solids remain on a filter membrane and form a cake. During the piston movement to the right, the cake is periodically moved to the edge of the drum. Consequently, a part of a cake is pushed out from the drum into the body with each piston stroke. After that the cake is discharged from the centrifuge through the chute. The piston is attached to the shaft-rod, installed inside the hollow shaft. The piston is connected to the device, imparting it reciprocating and rotational motion. A hollow shaft is used to rotate the drum. The piston and the drum move at the same frequency.
This type of centrifuge has a capacity greater than that one of discontinuous centrifuges. In addition, it requires little manual labor. Despite the obvious advantages, such centrifuge has several disadvantages such as high costs of electricity, consumed for the piston operation. Moreover, after the cake is discharged, the filtration quality is reduced since filtration occurs only in the area of the filter membrane with no cake layer.
Multistage pusher-type centrifuge is used for separation of suspensions in those cases where the solid phase layer has a sufficiently large thickness.
When cake thickness increases, the force, necessary to apply to the pusher, increases as well. At the same time, rotor speed is reduced and the cake humidity increases. These problems are effectively solved by multistage centrifuges.
Centrifuge rotor represents a number of filter drums of different length, arranged telescopically. During filtration process the suspension passes sequentially all the drums. Odd-numbered drums are attached to the rod and represent the pushers for even-numbered drums during the forward movement of the rod. Screens, through which the cake moves, are mounted in even-numbered drums. The edges of shells of these drums represent pushers for odd-numbered drums during the back motion of the rod.
The design of the multistage centrifuge, in comparison with a single-stage one, allows to reduce the length and thickness of the cake in the drum. As a result, cake pressing is improved considerably. Low energy consumption during cake discharge represents another advantage of this type of devices.
Continuous centrifuges are characterized by a higher performance index as compared to discontinuous centrifuges. In this regard, continuous centrifuges are widely used in industry and in small productions.
Discontinuous filtration centrifuges are used for treatment of such materials as:
Humidity of the cake at the outlet is:
Discontinuous settling centrifuges are designed to separate hard filterable suspensions. The cake is characterized by the outlet humidity of about 70%.
Automatic centrifuges (devices representing average units between discontinuous and continuous centrifuges) have good performance indices. The cake is removed with a knife, so that such centrifuges are not recommended for use in cases where it is undesired to damage structure of fibers or grains, making up the substance. Centrifuges, equipped with a pulsed piston, are used for operation with crystalline and fibrous materials.
Horizontal centrifuges with conveyor discharge are well suited for operation with suspensions, containing a large amount of finely divided solid particles. Such devices are also used as classifiers (for separation of grains by size, ores, sand, coal).
High-speed centrifuges are space-saving and leakfree, and, therefore, they are used for clarification of varnishes, as well as for working with hazardous and flammable liquids. Disc stack centrifuges are widely used in the dairy industry.
Centrifuges need a quality service. Care should be taken so that the drum rotation speed increases smoothly (without jerks), as well as vibration of the drum and the shaft should be prevented. To stop the centrifuge first the motor is switched off, and then the brake is actuated. When operating the centrifuge, it is necessary to follow the safety rules strictly.
Centrifugation is a process of liquid heterogeneous systems separation as a result of centrifugal forces action. This process is carried out by special devices (centrifuges). Perforated drum, rotating at the shaft (vertical or horizontal), is the main element of the centrifuge.
The following processes take place in a centrifuge:
Centrifugal filtration is a process of suspensions separation in centrifuges. In this case the centrifuges are equipped with perforated drums with the filter material layer, adjacent to them. Substance is thrown onto the drum walls, and liquid passes through the cake layer and through the fabric under the influence of centrifugal forces, and it is discharged through the outlets. Solid phase remains on the fabric surface.
In general, centrifugal filtration process includes three physical processes:
Centrifugal settling is a process for suspensions separation in centrifuges, equipped with drums, having nonperforated walls. The suspension is supplied into the bottom part of the drum and it is thrown to the walls as a result of centrifugal force action. The cake is separated on the walls, and the liquid creates an inner layer. Next, the liquid is pushed out by the suspension, which is supplied for separation. The liquid rises and overflows. In this case, two physical processes take place:
Centrifugal clarification is a process also occurring in the drum, having nonperforated walls, and used for separation of suspensions with low content of solid phase (fine suspensions, colloidal solutions). In the context of physics, this process is free of solid particles settling under the influence of centrifugal forces.
Drums, having nonperforated walls, also can separate emulsions. The emulsion components are separated into external high-density layer and internal low-density layer. Liquids, separated by phases, are discharged individually from the drum. This process combines settling and filtration under the influence of centrifugal forces.
Centrifugation is a more efficient method of liquid systems separation, compared to settling and filtration. The higher the centrifugal separation factor is, the higher the separation ability of the centrifuge is:
Ф = (ω²*r)/g
Where w is an angular rate of drum rotation, rad/s;
r is a drum radius in meters;
g is the acceleration due to gravity, 9.81 m/s2.
Centrifugal separation factor can be increased by the drum radius increasing and by number of revolutions increasing.
Performance index is one of the main parameters, characterizing a centrifuge, and it is calculated by the formula:
Σ = Ф*F, m²
Devices, intended for centrifugation, are classified by the following parameters:
Effective separation of liquid heterogeneous mixtures is carried out by means of centrifugation method. This method is based on the use of centrifugal force. Centrifugation is actively used in various technical fields. The number of designs and types of centrifuges is large.
A drum, rotating at a high speed on a horizontal or vertical shaft is the main part of the centrifuge. Non-homogeneous mixtures can be separated in the centrifuge on the principle of filtration or settling.
Drums, having nonperforated walls, are used during settling. Perforated drums, covered with filter material are used during the filtration process. In the event of using the drum, having nonperforated walls, the material is positioned in layers, under the action of centrifugal force, depending on the specific weight. At that, a layer of material with the highest specific weight is located at the drum walls. In the case of usage of the drum with perforated walls and filter membrane on the inner surface of the drum, the solid particles of filtrate are retained on the filter membrane. The liquid phase passes through the pores of the filter membrane and of a solid cake, and then it is discharged from the drum.
Centrifugation may be carried out according to the principle of settling and filtration. For this purpose, nonperforated or perforated drums are used. These processes are very different from each other in their physics. In addition, there exist certain types of each of these processes, which differ by the degree of dispersion of solid phase, by the number and physical properties of suspension itself.
Centrifugation in settling drums is used to clarify a liquid, containing a small amount of impurities, as well as to separate suspensions, containing large amounts of solid particles.
Process of centrifugation in settling drums consists of physical processes such as solid particles settling and cake thickening. Cake thickening process is based on the laws of mechanics of dispersed media. As long as the concentration of solid phase is up to 4.3%, settling occurs without the formation of an interface between liquid and solid phases. In the case, when solid phase concentration exceeds 4%, an interface of phases separation is formed during settling. This occurs as a result of enlargement and settling of particles, present in a liquid.
Centrifugation in settling drums differs considerably from the separation in settling tanks. The deposition rate in the settling tanks is assumed to be constant, since the process takes place in the gravitational field, and the acceleration of particles does not depend on their position in the gravity field. In addition, the force lines of centrifugal field are not parallel, so the direction of centrifugal force action will be different for different particles, located at different radii of rotation. Therefore, it is impossible to apply the pattern of settling processes to the centrifugation process in settling drums.
The process of centrifugation in filter drums is even more sophisticated. It develops in three stages. First, the cake is formed, and then it is thickened, and then the liquid, retained by molecular and capillary forces in the pores of cake, is discharged.
That is why the centrifugal filtration process has little to do with the process of normal filtration, which occurs due to gravity. Only the first period of the filtration process is very similar to a centrifugal filtration, but differs from it by the magnitude of the hydraulic pressure of liquid, flowing through the cake layer by the action of centrifugal force. During this period, the liquid located in the cake in a free form, may be naturally discharged from the cake. The next period is similar to the corresponding period during the settling centrifugation. The last period is characterized by cake thickening and air penetration into it. This process is called mechanical drying of cake.
The rate of liquid discharge from cake decreases during transition from the first period to the last one. At that, the liquid, retained by means of molecular forces, is not practically discharged. Consequently, the second and the third centrifugation periods occur according to the very different laws, different from the filtration process.
Duration of periods depends on the concentration of suspensions, centrifuges characteristics, and physical properties of suspensions. The first period occurs during centrifugation of diluted suspensions at prolonged supply of them into the drum. This period is almost non-existent or is of a short duration during centrifugation of most highly concentrated suspensions.
Filters
Upon becoming the official distributer of fabric filters, our company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), carries out the following: finds the buyers of your products on the market, conducts technical and commercial negotiations with the customers regarding the supplies of your equipment, concludes contracts. Should a bidding take place, we will collect and prepare all the documents required for the participation, conclude all the necessary contracts for the supply of your equipment, as well as register the goods (fabric filters) and conduct customs clearance procedures. We will also register a certificate of transaction (Passport of Deal) required for all foreign trade contracts in the foreign currency control department of the authorized Russian bank so that currency transaction could be effected. If required, our company will implement an equipment spacing project in order to integrate your equipment into the existing or newly built production plant.
We are convinced that our company ‘Intech GmbH’ LLC (ООО «Интех ГмбХ»), will become your reliable, qualified and efficient partner & distributor in Russia.
We are always open for cooperation, so let’s move forward together!
