ABOUT THE COMPANY 
Oven accessories
- steam generator The pressureless steam generator is a device for the additional production of technological steam for PPP baking band tunnel ovens. The stated generator becomes sufficient in the complete coverage of necessary technological steam, primarily concerning ovens with lower baking surfaces, upon the selection of suitable yeast and dough technology with the goal to decrease the amount of steam necessary in the hydrothermic zone of the band baking oven. The installation of BVP will not affect the baking characteristics of the oven (baking uniformity, baking curve etc.).
- band types PPP ovens can be equipped with various types of conveyor bands in relation to the required band qualities, baked product and also with regards to the financial means of the client.
- cleaning and oiling bands These devices are primarily used in narrow ovens with steel bands.
- extending the infeed and outfeed You have the option to equip PPP ovens with an extension on either the infeed, and/or outfeed part. It is suitable to extend the infeed part of the oven e.g. when it is equipped with a cutting device of the baked product together with automatic vertical setting from the proofing device, used in the pre-steam zone, or due to a number of other reasons.
- pre-steam This concerns both pre-steam related to the infeed area of the baking chamber of the oven, and the actual pre-steam chamber itself which is positioned independently in front of the oven infeed area. The length of this pre-steam zone is selected according to the required production technology and the number of installed steam pipes is changed in relation to the length.
- extended steam zone PPP ovens are generally equipped with a hydrothermic steam zone at the beginning of the baking chamber at 900 mm in length with three steam pipes. This standard steam zone can be extended up to 1275 mm in length and can be equipped with up to six steam pipes in relation to the size of the baking surface of the oven and the technological requirements of the production of the baked products.
- Hot-air curtain The hot-air curtain is used to divide the hydrothermic steam zone from the baking zone of the baking tunnel oven. This is primarily beneficial in cases where the occurrence of steam outside of the hydrothermic oven zone could cause unwanted effects on the baked product. Furthermore, this curtain can also be used for ovens without steam zones and its purpose then rests in increasing the moisture removal from the baked products and thereby improving the performance of the entire oven by adding a convection component for heat transfer to the typical radiating component. The air curtain can be turned on and off at any time, and the quantity of air forced into the baking chamber can also be regulated.
- moistening (water spraying) device Product moistening can be installed optionally at either the oven infeed area, and or its outfeed, as both raw and baked products can be moistened. The function of such a device is based on spraying the product with a water mist via nozzles. This device is available for all types and sizes of PPP ovens.
- band pre-heating PPP ovens are generally not equipped with band pre-heating because the return strand of the band is found under the bottom heating radiator, which like the entire heating system is placed in an insulated area of the oven. Due to this, the band does not cool on its return trip to the oven infeed area and unwanted loss of heat into the bakery is prevented. The only places where the conveyor band is cooled for as short a time as necessary due its transfer from the insulated area, is the outfeed area and oven drive area.
- DUOTHERM The duotherm circuit completes the radiation component of the transfer of heat to the baked product in the PPP tunnel oven with a convection component.
- fully automated control Fully automated control of the oven means that the oven is equipped with a Simatic S7-300 type master control computer or another similar system and the entire oven is controlled using the touch screen on the control panel.
- STIR technology
A patented ceramic layer with which we generally equip the second, third or even the fourth oven radiator. This special ceramic layer provides significantly faster heating of the baked products crumb than in comparison with common convection baking methods. Thus, the moisture release decreases, the size and quality of the baked product increases, its freshness is prolonged and the baking time is shortened by ca. 15%. With regards to cookies the time is decreased by 30% in relation to the type of baked product and the STIR zone length.
This optional accessory is applicable to all types and sizes of PPP cyclothermic ovens. This device is not applicable to tunnel ovens with electric heating due to their construction.
For more detailed information on STIR technology and its possibilities of use, visit the producer’s website www.infrabiotech.de
1 - common tunnel oven
2 - STIR technology
time difference in completing crumb stabilisation:
The effects of both forms of supplying heat are entirely different technologically speaking and serve as the deciding factor in the baking process, its speed and the qualities of the bakery product. Convection heat penetrates into the product from the outer surface to the core of the dough clone rather slowly considering the low heat conductivity of dough. As a result the core heats up to the temperature necessary for forming and stabilizing crumb in around 11 -15 minutes, depending on the thickness of the dough clone. During this period, the product’s surface is intensely heated and creates a thick crust, whose quality can only be affected by steam.
In contrast, transformed, selective infrared radiation penetrates to the roll’s core quickly, which reaches temperatures necessary for the formation of a quality crumb (approximately 97 °C) in about 4 to 5 minutes. As a result, the crust on the surface of the product is created rather more slowly and is thinner depending on the regulation of the convection heat supply, i.e. the temperature of the steam release mixture.
The result is a product with positive indicators of taste, which are maintained fresh for a long time and therefore the shelf-life is improved.
However this also suggests that there is also the possibility of effectively increasing the baking speed and thereby increasing the oven output. Its size is directly dependent on the percentage share of surface treated with STIR emitter.
This means that by applying STIR technology to PPP ovens it is possible to use smaller ovens for the required output and thereby save investment costs
- Utilisation of waste heat
- spare parts for PPC ovens In 2007, J4 took over all technical documentation, including trademarks, and thus became the sole legal successor of the company Továrny mlýnských strojů Pardubice (TMS – milling machinery works) which used to produce and supply ovens all over the world from 1973 – 1998.
The generator is a double-jacketed cylinder tank, insulated from the outside to decrease the escape of heat into the bakery area. There is water – steam space between the jackets, and the burner flame burns through the centre of the inner jacket. Once the combustion gases flow through the inner jacket of the generator, the combustion gases enter the baking oven. This system of organisation is more advantageous energy-wise in comparison with the generation of steam in typical, independent generators as the same heating system is used for the generation of steam and heating the oven and thereby one chimney loss is saved on each generator installed.
To heat the ovens it is suitable to release the steam from the BVP (ca. after 1 hr) outside of the oven. This steam diversion is enabled by a three-way valve installed on the steam strand of the BVP. The steam is diverted this way e.g. to the proofer, waste heat utilization unit and if necessary – outside of the bakery into the atmosphere. The slight disadvantage of this device is the increased demand on maintenance and the operating life in relation to the quality of the water being used to generate steam.
Pressureless steam generator (connection scheme):
| 1: burner 2: generator body 3: level indicator 4: supply float tank 5: water gauge 6: spherical cock 7: funnel 8: opening for cleaning |
9: oven insulation 10: water safety guard 11: three-way open valve 12: existing steam flow 13: sludge cock 14: sludge tank 15: steam flow to steam piping 16: spherical valve 17: throttle cock |
Wire mesh band:the most commonly used and most affordable type of band, which can be used for baking products on sheets or in tins, and for free set products baked directly on the band.
These bands can be used to equip any type and dimension of PPP ovens. The band is comprised of lateral wires of varying spacing, around which wire spirals are wound that can be wrapped around in different thicknesses, from various dimensions and types of wires (flat, round etc.).
Steel band: an all-metal, full sheet metal band which is generally used for narrow ovens designed for baking thinner dough e.g. sponge cake dough and it is also suitable for narrow ovens with a non-standard longer baking area. It is primarily implemented in confectionary and durable pastry businesses.
These bands can also be supplied perforated, but their use needs to be considered carefully in advance with regards to the character and technology of the baked product.
Link plate band: an all-metal band created from sheet metal plates – links, which are set into lateral wires connected by side guide chains. They are not only suitable for narrow and standard ovens, but also for our high temperature pre-bake ovens. These bands are noted for their unified surface and ability to accumulate greater amounts of heat, which apart from others, is beneficial in the formation of a stronger bottom crust on baked products and therefore it is also possible to state that they can be considered as a less expensive substitute for a band made from granite plates.
Link wire band: these types of bands are primarily suited for ovens of greater dimensions where the baking is performed on sheets or in tins, because these bands are noted for their higher bearing capacity. Also, with regards to their construction, when implemented in PPP ovens with duotherm, these bands enable more efficient heat transfer into the baking product, which is an advantage in the instance of e.g. tin bread baking.
Granite plate band: this type of band is created from granite-stone plates positioned in benches, which are connected along the side with massive guide chains. They are not only suitable for narrow and standard ovens, but also for our high temperature pre-bake ovens. This band is primarily noted for its unified, flat surface and the highest ability to accumulate heat in comparison with other band types. This is mainly beneficial in baking products with the necessity to form a solid and thick bottom crust, and for a number of other types of bakery products.
Oiling: the oven infeed can be optionally equipped with a fully or semi-automated device for oiling the steel band, which prevents the product from being baked into the oven band.
Cleaning: a brush can be positioned on the drive cylinder of the steel band, which cleans the remaining impurities on the steel band by its rotating movement.
The infeed extension can be equipped with a heating “nose” (positioned under the baking band), which aids in accelerating the heating process of the band prior to entering the oven. It can be of various lengths, depending on the length of the extension.
Infeed and outfeed oven extensions are supplied in various lengths and widths according to the width of the oven and they are available for all types of PPP ovens produced and supplied by us.
The main benefit of using this pre-steam is that the product is steamed in a “cold”, unheated chamber in front of the oven, thereby attaining much better adhesion of the steam to the product, thus also providing more effective use of steam. The use of pre-steam is suitable for both the production of pure black rye or rye-wheat bread, and for a number of other, entirely different products depending on local custom and traditional production technologies of the client.
The standard length of the pre-steam installed on the oven infeed area is 650 mm and it contains three double-jacketed steam pipes with 100% condensate separation.
This optional accessory is available for all types and sizes of PPP ovens.
Pre-steam with three steam pipes installed on the oven infeed area in close relation to the oven baking tunnel:
Pre-steam chamber of larger dimensions with five steam pipes positioned independently in front of the oven infeed area:
This optional accessory is available for all types and sizes of PPP ovens.
The hot-air curtain consists of a pipe with jets placed behind the steam zone where hot air is forced through the jets towards the hydrothermic steam zone, which prevents unwanted loss of steam into the rear parts of the oven baking tunnel.
The inlet of this pipe is connected to spiral piping leading through the combustion chamber of the oven where the air flowing through is heated and this piping is then connected to the fan positioned on the oven burner tower. This fan is equipped with a throttle flap for suctioning which enables regulation of the quantity of supplied air to the hot-air curtain. This air is generally freely suctioned from the surrounding area of the bakery and the entire system is separated gas-tight from the heating system of the oven in order to prevent the loss of combusted gases from the heating system into the oven baking tunnel.
This accessory is available for all types and sizes of PPP cyclothermic ovens. This device is not available to ovens with electrical heating, due to their different structural arrangement.
Scheme of a hot-air curtain:
Moistening of raw products at the oven infeed area is used to decrease the temperature of the surface of proofed products entering the oven baking tunnel, which is equipped with a steam zone, thereby significantly increasing the effectiveness of the entire steam process. As a result, the steam sticks better to the product thanks to maintaining a lower surface temperature for a longer period of time.
Moistening of baked products at the oven outfeed is mainly used in achieving the greatest possible surface shine and overall attractive appearance of the baked product.
In case of need to increase the band temperature by approx. 50°C at the oven infeed point in comparison with standard temperatures, it is possible to equip all PPP oven types with band pre-heating. Its intensity is easy to regulate with the help of independent heat dampers. Band heating of greater intensity takes place in the front part of the oven, just before its transfer into the insulated space of the bottom part of the oven infeed.
When using an extended oven infeed point with a nose-type extension, which is positioned under the conveyor band and extends all the way to the oven infeed in combination with band pre-heating it is possible to achieve maximum possible band temperature all the way to the oven infeed point and the bottom heat transfer to the product just before it actually enters the oven baking tunnel.
This accessory increases the oven’s output, strengthens the colouring of the side of the baked product, decreases the necessary baking time, increases the percent of moisture release, and increases the heat transfer surface of the oven radiator.
The following diagram depicts two circulating temperature circuits.
The first is the heating circuit – cyclotherm – which is a source of heat for baking. It consists of a
burner 1)
with a flame 2)
and mixing chambers for hot and warm combustion gases 3)
The mixed combustion gases are distributed via ducts 4)
into the upper 5)
and bottom 6) radiator of the baking tunnel.
To fulfil the function – releasing heat the by radiation method – the cooled combustion gases are suctioned by
ducts 7)
to the suctioning socket of the “oven heart – the circulator fan” 8).
This presses the cooled combustion gases back into the mixing chamber and the entire process repeats itself “round and round.”
Natural gas combustion circulates here!!!
The second circuit – duotherm – has nothing in common with the first with regards to pressure. It simply completes and expands the heat transfer by a component of convection. It consists of a rotating short right and left circuit. The source of the pressure gradient is once again the low-pressure fan DN 300 mm
with an elmotor 10)
The suctioning socket 11)
of the fan suctions rotating from the right and left side of the baking oven tunnel and drives the baking atmosphere (hereinafter the atmosphere) via the delivery socket 12)
through the bottom lateral duct all the way to the exhaust socket 13)
by a diameter of 2”. The atmosphere heats up along the way. The atmosphere permeates through the mesh band, through spaces between products thereby transferring heat by flowing around the sides of the product.
The atmosphere 14)
is once again suctioned by the suction socket 11)
The entire cycle is repeated “over and over again.” In the case of steel bands and upon the client’s request, the bottom duotherm can be replaces or completed by an upper duotherm.
Atmosphere circulates here – atmosphere is surrounding the product!!!
This system is available for all oven types and sizes. Bottom duotherm applies to all ovens except for ovens, which are equipped with non-perforated steel bands, where upper duotherm is used due to the impermeability of the full, non-perforated steel band.
It is possible to store up to 48 recipes on this computer. Each recipe includes setting up the time temperature curve in the baking tunnel using dampers in the upper and bottom heating of the controlled servo drive. Furthermore settings of the dampers for exhaust excess steam from the baking area, turn on and then automatic regulation of the amount of in-feeding steam, set up of the baking time and controlling other accessories installed on the oven. The computer programme also includes automatic oven start-up and its safe and efficient shut down once the production is completed, or in the event of a planned shut down.
The master computer also notifies the user of necessary maintenance checks of safety elements, which ensure trouble-free operation of PPP tunnel ovens in intervals as set by the producer. In addition, the master computer evaluates and stores all non-standard events that occurred during operation into its memory.
Attendance of such equipped ovens is only in the form of supervision and does not demand continuous monitoring of the settings and operational function of the oven.
It is also possible to set the access level in the computer, i.e. that using a password you can determine who is authorised to change the recipe settings, to confirm the specified oven maintenance has been performed, to change more serious systems settings and who can set the required oven recipe or turn the oven on or off.
Such a control system can also be connected to a computer network and the oven functions can be controlled and monitored from a remote computer. The energy consumption in relation to the operation time and the quantity of baked products can also be evaluated and thereby, easily keep track of operating costs of both the oven and the entire production line.
This control system can be used on all types and sizes of PPP ovens. Furthermore, it is possible to only equip the oven with a touch screen master computer, without automatic servo drive of the controlled dampers, where you can then only set the burner output and baking time, however with the help of recipes. The time temperature curve, regulation of the amount of steam supply and other settings must be carried out manually.
This device serves to utilise waste heat and according to the baker’s need, the acquired heat is used in heating hot supply and technological water, heating buildings and for air-conditioning units.
Our company presently uses and supplies exchangers provided by the German company NET, which we can highly recommend. The effectiveness of this device competes well with established top local and foreign suppliers, but without intervening with the oven’s cyclotherm and thus without creating critical situations. To make the right, optimum decision it is necessary to measure the band oven supply prior to installing the device for the utilisation of waste heat and to then measure it with the device. The use of unsuitable types of devices for waste heat utilisation may lead to an increase in the oven’s gas consumption and thus devaluate the entire system. NET equipment has one big advantage and that is minimum maintenance. In addition, it has the advantage that it is not necessary to change any fillings or to add water (operating costs are this minimised), no big pipes from combustion gases exhaust need to be installed and dragged about the bakery which makes the operation of this equipment significantly safer, cheaper and more reliable and waste water treatment does not need to be addressed. When installing some types of waste heat utilisation equipment we have to conclude that the higher the equipment’s effectiveness is, the lower the effectiveness of the cyclothermic oven is, which can not be said about the technology we provide.
Last but not least it is necessary to mention that the cost of NET equipment is generally half the cost of the existing top suppliers.
Hitherto J4 has been solely using NET exchangers with a small distributor for connecting the primary circuit of the bearing medium. However, the exchanger’s connection to the primary circulating circuit and other related technology are not included in our standard supply. In case of interest in complete processing and supply of the technology for waste heat utilisation, we can recommend a Czech company, which deals with this issue. (see www.ventos.cz for more details about complete solutions)
Equipment for acquiring waste heat can be used on all sizes and types of PPP cyclothermic ovens, however with the exception of electrically heated ovens.
Therefore, our company has not only been dealing with the service and production of spare parts for PPC type ovens, but also with the modernisation and further required modifications of this type of ovens.
