A seed dehulling machine NVH type (special hull separator) with performance 80 tons per day is designed for assorting of dehulled sunflower seeds on fat-and-oil industry enterprises.  



Technological performance by feedstock (dehulled product), min. tons per day


Oil content (without wax) in outgoing hulls above commercial, max., %

             from settling chambers


                      after control


Hulls content in the kernel, max., %


Kernel loss with hulls, max., %


Rated capacity, kW


Circular vibration frequency of sifter, С –1


Circular vibration trajectory radius, mm


Fan shaft speed, С –1


Air consumption, max., m3/h


Required space in assembly, max., m2


Specific energy consumption, max., kW/h/ton


Overall dimensions, max., mm







Weight, kg (max)

3300 (3500)  ****


* If the machine is operated on dehulled product from hybrid sunflower seeds with high oil content, then the content of unhulled or partially hulled seeds will be max 25%, oil containing dust will be max. 10% and chop – max. 15% (if operated on dehulled product from commercial sunflower seeds, absolute values of designed capacity shall be improved (decreased) by half, for example, kernel huskness will be 8% instead of 12%).

** If the machine is operated at hulls control with oil content (without wax) max. 1%.

*** Depending on a sunflower size the frequency can be changed within the range from 3.17 to 3.58 С-1. A required sifter vibration frequency is set by means of electric motor changeable sheave wheel selection: Ø 126 mm, Ø 142 mm. Sheave wheels are supplied on special order. The sifter is equipped with Ø 132 mm sheave wheel.

****Without spare, installation and replacement parts.

Operation and description

Science-based principles of dehulled product separation on hulls and kernels on the basis of size range and aerodynamic properties difference are at the heart of this seed dehulling machine NVH type design. A lightweight hulls with bigger surface area and lower weight shows higher sailing capacity in the air flow (the movability in relatively low air speed) than a kernel. That is why if dehulled product contains hulls and kernels particles of the same size, they can be clearly separated in the air stream due to their significant difference in sailing capacity.

The dehulled product coming out of dehulling machines (NRH or RC-200) after dehulling of sunflower seeds represents a mixture of different by size particles: large, medium and small husk, unhulled and partially hulled seeds, kernels, half kernels (chop), small hulls and kernel particles, oil containing dust. It is impossible to separate such complex mixture at once.

Thus, at the first stage dehulled product is separated by linear dimensions in the sifter (with preliminary sifting), on sizing screens to six fractions containing hulls and kernels particles of the same size.

At the second stage, in the machine aspiration part (purifier) from dimensioned dehulled product fractions in down coming air flow (each fraction in the separate channel with controlled air flow) hulls particles are separated from particles of partially hulled seeds, chop and kernels due to different aerodynamic properties of their sailing capacity. 

The smallest fraction (through scalp from Ø 3 mm screen), which contains very small particles of crushed kernels, mostly without husk (oil containing dust), is not separated in the air flow, it is directed to kernel fraction bypassing the purifier (non-purifying through scalp), as even at low speed of air flow, oil containing dust will be moved along with the husk and the separation will not happen.

The machine (pic. 1) consists of purifier 1, purifier drive 2, sifter 3 with preliminary sifting 14 and non-purifying tube 4.

The purifier is an aspiration part of machine. Across the width the purifier is divided into five independent chambers. Each chamber has three cone parts with adjoining overhead valves 6 for husk removal; valves 8 for control of vented air quantity; feed valves 19.

The purifier drive consists of fan and electric motor arranged on rigid frame. The fan is driven by electric motor via V-belt transmission.

The sifter is represented by a metal body mounted on ceiling frame by four steel wire ropes 9 turned over supporting blocks 10. The frame is fixed to roof with bolts. Wire ropes are fixed to the sifter with locks 11 and slips 12. Three layers of screening frames 13 are located inside the body.

In the front part of the sifter (overhead) is located a preliminary sifting unit 14 with two layers of screening frames. Inlet nozzle 15 of preliminary sifting unit is connected with a fabric gravity sleeve that delivers product to the machine.

In the rear part of the sifter is located a lead box 16 with overflow valves, under which are located sifter outlet nozzles connected with purifier inlet nozzles by fabric sleeves 17.

In the supporting frame (traverse) bearings are installed. Within bearings the shaft with equalizer bars rotates 18. The shaft rotation is driven by electric motor via V-belt transmission. 

Dehulled product fractionation process

Seeds dehulled on dehulling machines (NRH or RC-200) are delivered to sifter inlet nozzle and then from distribution pans are removed to upper screens of preliminary sifting unit (Ø 3 mm). A scalp (the product that fails to come through screens) consequently enters to lower screens of preliminary sifting unit (Ø 3 mm). A through scalp (the product that comes through screens) from upper and lower screens of preliminary sifting unit (non-purifying through scalp - the smallest part of crushed kernels mixture that mostly does not contain husk) enters to inclined pans. Then it is combined and directed to non-purifying tube and is combined with the kernels coming out of dehuller without additional processing.

The dehulled product after preliminary sifting unit comes to long upper screen with Ø 6 mm holes (2/3 of layer length) and moves to the purifier front part. The smaller particles of dehulled product fall through the screen (through scalp) and by (through) screen pan come to the second layer screen; the larger particles after long upper screen come to Ø 7 mm short upper screen (1/3 of layer length), where the largest particles (large husk, unhulled and partially hulled seeds) come as a scalp, forming the first dehulled product fraction and is directed to the first purifier chamber. A through scalp from the short screen forms the second fraction that is directed to the second purifier chamber.

The second layer of screens has holes of Ø 4.5 mm (2/3 of layer length) and Ø 5 mm (1/3 of layer length). The scalp from these screens is directed to the third purifier chamber. The through scalp from Ø 4.5 mm screens comes to the third layer of sifter screens. The through scalp from Ø 5 mm screens comes to the forth purifier chamber. The third layer of screens has holes of Ø 3 mm. The scalp from these screens comes to the fifth purifier chamber. The through scalp from Ø 3 mm screens comes by pans to the non-purifying tube and removes from the machine bypassing the purifier and is combined with kernels coming out of dehuller.

Screen pans are installed on the first and second layers of 2/3 screening frames, in order to decrease time of oil containing dust contact with husk. It decreases oil loss with hulls.

Consequently the dehulled product free from the largest particles comes through the pan of long upper screen to the middle screen, where third and fourth fractions are separated. The smaller dehulled product comes through the pan of middle upper screen to lower screen, where the scalp forms the fifth fraction and the through scalp forms the sixth (the smallest) dehulled product fraction that is removed from machine bypassing the purifier.

Each of five product fractions that enter to the purifier, come to the designated chamber where the product is purified by air flow and husk is separated from kernels according to difference in aerodynamic properties.

The aspiration chamber has five air ducts for dehulled product processing. Dehulled product fractions obtained from sifter come to that air ducts. Each duct is divided into three parts: receiving, settling and outlet.

The receiving part is equipped with stepwise located four shelves (shutters) made of metal sheet. Slots for air intake by fan from the production facility are foreseen between shelves. Shelves are set at an angle 30-35° to the horizontal.

Each dehulled product fraction enters the top shelf and then by gravity pours from shelf to shelf. The air flow penetrates falling dehulled product layer and removes the lighter particles (husk), starting from the last shelf come kernels free from hulls. Shelf angle can be changed due to purifier regulation: the lower angle is, the faster dehulled product falls on them, the shorter air treatment is and the lesser hulls selection is.

The settling part of aspiration duct consists of three cones (pockets) with valves for removal of products and vertical baffles for changing direction of air removed hulls particles. The air flow is created by the fan. In order to control air conditions (air speed) each duct is equipped with gate valve, which position can be changed from the receiving purifier part (where shelves are located) using a hand wheel and wire rope cable.

After passing between shelves air that removes husk enters to the expanding over the first cone (re-purifying) part of aspiration duct. The air speed decreases and in the first cone, in case of inaccurate separation by aerodynamic properties, large hulls and kernels, partially removed by air flow along with hulls, are settled together. In correctly adjusted operating regime the kernel content in first cone shall not exceed 1-2%. The fraction settled in the first cone shall be directed to re-separation and that is why it is called re-purified seeds.

Hulls that were not settled in the first cone are removed by air further and pass between vertical baffles over second and third cones. By hitting at cones hulls slow down and settle. The husk movement slowing carries out due to increase of aspiration channel cross section over cones, resulting in husk settling in second and third cones of aspiration chamber. The air containing very small hulls and, possibly, small kernel particles (oil containing dust) enters to cyclones through fans.

The air speed in ducts is controlled by bigger or smaller gate valve opening, by changing elevation of regulating valves and inner baffles, shelves (shutters) inclination to horizon. The purpose of such regulation is deficiency of kernels in hulls in second and third cones (to prevent kernel removal to husk).

Therefore, after aspiration purification we receive the following products: kernels (from second, third, fourth and fifth sections of aspiration chamber), oil containing dust (VI fraction of the sifter), partially hulled seeds (from first section of aspiration chamber), re-purified seeds (from first cone) and husk (from second and third cones of purifier aspiration chamber). A settlement from air-cleaning facilities exhausted by the fan from purifier aspiration chamber, depending on the content (oil containing dust or small hulls), is added to kernels or hulls.

More operations on fractions after dehulling machine

Kernels from working purifiers are directed to further processing. Partially hulled product basically composed of unhulled and partially hulled seeds and large husk is directed to cleaning/screening machine (BSH-100 separator for partially hulled seeds control) for additional separation of large husk and coarse litter.

An enriched partially hulled product with lower husk content is directed to re-purification, sometimes even to special designated (control) purification, control of which ensures more intensive impact on seeds.

Re-purified seeds are directed to re-separation by special control purifier which differs from the working one by screen holes sizes and air conditions in aspiration chamber.

Hulls coming out from husk purifier cones are separated into hulls and kernels, first on separate purifier sifter and then in aspiration chamber. Further, husk is delivered to the storage and kernels (plus kernels from control purifier) are delivered for crushing.

If aspiration purifier is operated properly, dehulled product samples taken from 1-4 shelves sections shall not contain through scalp after 3 mm screening. If there is such through scalp in the dehulled product from the first section, it indicates that purifier is overloaded; through scalp from 2-4 sections indicates that sifter works unsatisfactory in the result of improper selection of screen holes size.

Comparative analysis

The special seed dehulling machine (NVH) for fractionation of dehulled sunflower seeds is used only at the post-Soviet region.

All censorious remarks to NVH can be limited to only 2:

  • additional oil treatment of hulls due to long-term contact with crushed kernels during screening fractionation;

  • requirements for larger by floor area premises in comparison with two-stages front-end dehulling on cleaning/screening machines and separators used by “Buhler” or “Allocco”.

There is no ideal process. In theory it exists. In the real life it does not. Everything is relative. Our process can be compared with the only competitive process solution – two-stages front-end dehulling on cleaning/screening machines and separators used by “Buhler” or “Allocco”:

  • of course, processes with two-stages front-end dehulling require smaller premises by floor area, but larger by stud (height);
  • additional oil treatment of hulls also is carried out on separators screens, but purification degree of universal separators is lower than on specially designed machine (see process description section). The kernel loss with hulls, at least, on 0.5% higher in two-stages front-end dehulling process in comparison with seed dehulling machines. For oil extraction plants with capacity 500 tons per day it is the loss of min. 80 tons of oil per year. In monetary terms it is equal to 64000 USD (with wholesale price 800 USD for 1 ton of oil).

There are numerous theoretical concepts that try to solve a problem with additional oil treatment of husk:

  • centrifugal separator;

  • electrostatic separator;

  • cascade and cone pneumatic separator, etc.

There are even some working complexes, but:

  • firstly, oil treatment decreases, but purification quality deteriorates;

  • secondly, there are no data about commercial operation confirmed by specifications obtained in laboratory conditions.

Recent years an issue of oil loss with hulls our plant successfully solves using beater SL-40 (machine for additional cleaning of sunflower hulls) for additional separation of oil containing dust from sunflower hulls.

Only such technological process provides an opportunity to reach the following quality indexes in commercial production:

  • kernel content in the hulls – max. 1 %;

  • hulls oil content without kernel – max. 1.2 % higher than botanical;

  • hulls content in the kernel – max. 10 %.

Above-mentioned average indexes are calculated for mixed raw materials (commercial mixture) without preliminary grading. After grading, processing of homogeneous raw materials bulk or operational regulation of dehullers and dehulling machines options during production process, the following indexes can be reached:

  • kernel content in the hulls – max. 0.8 %;

  • hulls oil content without kernel – max. 1 % higher than botanical;

  • hulls content in the kernel – max. 8 %.

As the long-term experience of hundreds of old and new oil extraction plants operation shows, the technological process of sunflower dehulled product separation for obtaining kernel fraction with max. 10% husk content based on NVH dehulling machine is unchallenged. And as the plant that has manufactured far more than 1000 machines since 2000 year, we can boldly declare that there are prophets MACHINES in our country.

A basic circuit arrangement of dehulling machines R1-MST, R1-MS-2T (prototypes of NVH) was developed decades ago and proved its efficiency, but time passes, new materials and technologies develops, operation experience accumulates and our plant constantly improves construction involving professionals from leading research organizations. The examples of such researches are shown in the tab “Materials”.

Частотный анализ конструкции корпуса «Рассев НВХ»

Определение источников вибрации элементов конструкции «НВХ-Вентилятор» при действии эксплуатационных нагрузок и наличии радиальных зазоров в подшипниках

Прочностной и частотный анализ конструкции ротора балансира НВХ


Принципиальная схема семеновеечной машины Р1-МСТ, Р1-МС-2Т (праобраза НВХ) разработана много десятилетий назад и доказала свою эффективность, но идет время, появляются новые материалы и технологии, нарабатывается опыт эксплуатации, завод постоянно совершенствует конструкцию с привлечением специалистов ведущих научных организаций. С примерами таких исследований вы можете ознакомиться на вкладке «материалы»

Частотный анализ конструкции корпуса «Рассев НВХ»

Определение источников вибрации элементов конструкции «НВХ-Вентилятор» при действии эксплуатационных нагрузок и наличии радиальных зазоров в подшипниках

Прочностной и частотный анализ конструкции ротора балансира НВХ