Intellectual Property India Publishes Patent Application for - Tertiary Air Duct/Flue Duct Damper With Ss Slide Gate With Air Jacket Arrangement And Lined With Pre-Cast Pre-Baked (pcpb) Refractory Blocks And Air-Cooling System For Slide Plate Jacket Zone For Cement Manufacturing

MUMBAI, India, Aug. 10 -- Intellectual Property India has published a patent application (202511077894 A) filed by Humboldt Wedag India Private Limited on August 15, 2025, for - Tertiary Air Duct/Flue Duct Damper With Ss Slide Gate With Air Jacket Arrangement And Lined With Pre-Cast Pre-Baked (pcpb) Refractory Blocks And Air-Cooling System For Slide Plate Jacket Zone For Cement Manufacturing.

Inventor includes Humboldt Wedag India Private Limited.

The application for the patent was published on July 31, 2026, under issue no. 31/2026.

Abstract: BACKGROUND Background of the development of the product and process explanation. Background The precursor to modern-day cement was created in 1824, which was having number of drawbacks like high energy consumption, primarily due to the need to evaporate large amounts of water, and significant dust generation. But over the period of Cement manufacturing process evolution in recent times Tertiary air recycling to Preheater is heat efficient method for Cement production as well as Carbon foot print reduction. For a long time the Cement Industry is using Castable based protection for the slide gate which have potential for cracking due to thermal shock and chemical attack, higher thermal conductivity leading to heat loss, and susceptibility to erosion from process materials and is regulating the tertiary air back to PH based on process requirements. Off late People use complete Pre cast Refractory for such application which has limited life and demand total replacement with long layoff period causing plant productivity. The damper lined with Castable has very limited life due to Thermal expansions , abrasion (High velocity gas) and corrosion due complex gas and duct medium. This is happening due to recycled Gas (chemical), and (Physical) high velocity, abrasive dust operation conditions. The above situation demands plant usage down time as well as extra cost of rework. Industry is exploring new alternatives. Objective : Process / Product Development 1. Existing designs problem faced was due to the thermal expansions of existing designs where either refractory is fixed on • the plate laid with castable in situ with anchors directly weld on the plate • lattice members laid with castable in situ with anchors directly weld on the plate • pipe structure laid with castable in situ with anchors directly weld on the plate • total refractory blocks holding bracket from top 2. Problems were faced in first three mentioned past design mentioned above was that: o The thermal expansion of Castable refractory and steel are way different o So while in operation the steel expand more than castable leading to surface cracks o Once surface cracked formed this will be filled with dust which is in the medium start wearing castable faster ( at say 800 to 1200 Deg. C). while on stoppages dust filled shall impart compressive forces and further disturb castable anchoring o With above effect castable start falling, wearing or projecting out towards the limited dimensions available in the gate housing body internally. This projections interfere and add on extra load on drive . Since drive is designed with extra load operation it force the gate movement but in the process disturb disorient the castable further and expose metal body to the operation with out insulation protection and base body also get damaged o When operator regulate the damper ( open or close ) , further the castable will block free up and down drive movement and either trip drive motor on overload or further damage the castable in movements. o While the castable get damage it can damage Plates, lattice frames or pipes for its function and impart a total damage over say 3 -6 months depending on quality of castable laid operational frequencies etc. o Above essential force existing design to have higher drive KW and bi directional acting linear rigid actuator is only possible. This adds size of equipment by hight and weight, Force, cost, maintenance hassles, recurring repair demand and plant turn down time. o Further when there are cracks gaps formed in the castable due to relative expansion parity of castable and Steel , during plant operation at 800-1200 deg. C process air passage with high abrasive dust and chemical compositions in air, The steel parts wear fast. o Industry is facing this trouble shoot and they tried for total refractory options with holding frame. But this can only be replaced totally . Partial repair impossible. Cost of repair total, High cost inventory and turn down time ( non plant productive time ( loss of revenue)) and heavy lifting cranes etc for repair which adds cost. 3. HWI New Design Process difference • HWI design eliminate Castable in situ lining totally. • HWI decided to mitigate differential expansion of steel and refractory by allowing expansion of refractory with out change or deformation of refractory Shapes which are Pre Cast and pre backed (PCPB) with special shape configuration. • These shapes are very thought fully developed in with clear intend for following Easy expansion and contraction with SS Flap and refractory, Refractory blocks and refractory blocks ( refractory Blocks are mounted on Stainless Steel jacketed plate construction with provisions of air cooling jacket internally and insulation layer and PCPB refractory block fixing on both side of flap. Now with this process of design there shall be sliding adjustment of relative expansions with out affecting each component from its designed shapes. Even in variations of temperature ( start and stop), or on regulation of damper on upward and down ward movement. This ensures no additional load to drive . and give flexibility to operate both bidirectional rigid drive ( linear actuator and drive transmission shaft). In first stage HWI shall establish the reliability of the Flap and refractory so that it gives free up and down movement . This open up design process improvement to manage downward movement by gravity force In such a case flexible chain drive or a winch drive is envisaged. a. Slide gate Flaps on which the PCPB refractory is fixed on both sides have following design process considerations which are specifically part of patent registration b. Air cooling Jacketing for assured air passage and flow for ensuring cooling of Flaps for its life and control of SS plate expansion. c. Reinforcements with in Flaps for and mechanical distortion d. Insulation are considered for the Stainless steel Flaps on both sides (PCPB refractory specially designed). e. Interlocking and special shapes concept which dimensionally match to different diameter range of dampers • Specially shaped precast pre Baked Refractory blocks PCPB)which interlocks each other to impart strength , stability and thermal expansion/ contractions . These blocks are individually fixed by SS hardware on the all surfaces of Slide gate . This can be easily removed and repaired locally depending of wear with minimum time , inventory and handling tools / manpower. Our company offer composite service for such repairs. This reduces the recuring cost down time and inventory money blockage. The refractory selection is to suit Chemical, Mechanical abrasion, High thermal shocks. • Anchoring of the PCPB blocks fixing arrangement are designed to meet high heat application to avoid thermal stresses and self weight of PCPB. • Chemical composition of refractory of Pre cast Pre backed block is specially selected to counter Chemical , mechanical wear , requirements of operational duty. • Continuous temperature measurement of the cooling air circulating inside slide gate offers a continuous feed back to the plant operation screen whether there is a local failure of the gate so that a maintenance demand up coming. 4. Liner actor is standard product exist in market standard products available in market but designed to suit our design criteria of this design. But which is selected at present for bidirectional movement loads . However this may get upgraded with a flexible wire rope or chain drive as second stage design. We reserve our right to improve design in these two options 5. Air cooling fans and connection pipes are standard products available in market but designed to suit our design criteria of this design 6. Transmission shaft and up frames are designed to suit linear actuator drive mounting and the load requirement of flap movement etc. This may undergo revision if winch drive or chain drive designs are incorporated in in due course. 7. TAD damper Housing is designed to meet the duct size, and the slide plate size and PCPB refractory dimension requirements , and load requirements of drive and its dimensions. Our invented process is modified from the above traditional process and it is as below 1. Selected right raw materials for the Slide gate Plate such as Stainless Steel (SS) to meet high temperature. 2. Flap / Plate design have been made more sturdy and reliable. 3. Refractory composition to meet the high temperature, chemical wear, abrasion of the operating gas high dust etc. 4. Air cooling of flaps made to ensure that the base material is safe from distortion, controlled expansion. 5. Slide gate have been made with plate sandwiched jacket which is reinforced suitably to avoid any distortion due to high heat application at different temperature gradient operation of plate body. 6. Refractory PCPB block geometry is selected to have easy fixing and removal to save cost and down time of plant. The Geometry of the refractory PCPB blocks are such a way the expansions are mutually adjusted and do not initiate any undue / unprecedented crack or formation 7. The fixing of PCPB refractory blocks were individually done to assure the reliability of the design. 8. Fixing hardware and its protection have been done specially so that chances of failure is eliminated All above stated features were not present in all existing design . Analysis M/s HWI is a subsidiary of a Cement technology engineering company listed in Frankfurt formed almost 170 years back. The Pre Heater technology in Cement plant was first Conceived By HW Germany. Previously all Cement plant in world and India etc was liquid slurry calcination process which was changed to a solid powder form of Lime stone with desired additives. Subsequently Industry started to for more fuel efficient and reducing carbon foot print recycling of Flue gas / got gas from system back to the process of cement making via Tertiary Air duct ( TAD ) got into practice in may be in 1970 s. Since then the importance of Tertiary Air duct TAD kept increasing as recirculating hot air and its regulation depending on raw material quality of Input material of cement became very important. HWI being such old experts in this field had internal feed back from Many customer regarding the trouble shoot of this equipment as a part of it Warrantee experiences of plants / contracts. We have a clear insight of the issues faced by all major producers of Cement in World including America, Europe, China , India, Australia and sub Saharan regions. Based on various feed back of Client and present practices of repairs high lighted elaborated elsewhere are still practiced experience in the industry . Hence the area where solution required are very clear and same is already explained. Sl. No Description of feature Old Existing New HWI Design under patent 1.0 Drive Winch driven / Dual rack and pinion/ Linear Actuators . HWI had Traditional linear actuator design HWI reserve its choice of using its traditional Linear actuator of existing OEM or migrate to a new Winch and drum arrangement . 2.0 Slide Plates Single plate to hold refractory mostly MS / SS construction considering Huge refractory Castable Or complete refractory blocks hanging from a Holding MS beam or member out side housing Stainless steel double steel plate Jacketed design dully reinforced in special way for air Cooling passage using continual heat exchange method . Mechanical designed for thermal distortion chances. 3.0 Refractory In Situ castable were fixed with Y anchors and poured into the shape of Gate with wooden shuttering as we do the casting of Building Column or beams etc. As regards the Solid Refractory block design with external Holding arrangement : No idea about Refractory composition HWI has taken SKG refractories for specific application requirement with Heat wear protection and reinforcement SS fiber for long life. The shapes of PCPB Pre Cast Prebaked ( PCPB ) refractory are specially developed so that inter block expansion is compensated with out and failure and can be repaired locally with out dismantling the TAD damper with cranes of heavy equipment. In addition we have X mm insulation blocks behind solid blocks so that the SS plate temperature is maintained with Air cooling and the Insulating layer. With Air cooling base equipment failure chances are remote in new developed New invention. All the above feature in HWI knowledge is not used by any one so far in the industry 4.0 Fixing of refractory Blocks ( PCPB) on to the slide plate Castable are cast with wooden shuttering as one block. Refractory block only design is direct suspension from top HWI Invented design is small refractory with very less weight fixed individually by Stud and bolt and sealed properly to protect the holding bolt from any damage. Old castable will break in differential thermal expansion of Steel and Castable. Replacement can be only total . Suspended Block is risky and replacement can only be total . New Invention mitigates all negative existing issues. As regards to repairs 5.0 Refractory geometry Castable single in situ casting block . Heavy Standard square / interfering shape with different fixing protocol by holding from top external . No insulation layer Light special geometry developed for Interlocking individual locking fixing, Insulation layer. Expansion and contraction shall not affect each brick as tolerances or gap between blocks are enough to cater expansion because the size are small ( thermal expansion is directly proportion to the size of an integral block. There are two types of PCPB bricks depending on sizes of TAD damper in diameter. 1. Standard size applicable for any size. Standard mould were developed as HWI property 2. Non standard size keep on varying for which every time a new mould are prepared . One size mould is already developed. 3. Mould are special steel shapes into which the special refractory composition is poured in and dried 6.0 Insulation layer for heat protection In existing Castable design Insulation layer is placed . But since Y type anchors are there to lay insulation is very difficult and the effectiveness of insulation at in situ laying is not good . This also affect life of Slide gate at present. In refractory block design No insulation considered In HWI new invention insulation layer can be fixed properly so that the effectiveness 100%. This ensure safety of SS slide plate and thermal impact on the SS Slide plate. In old design when the castable crack even the insulation layer also crack along as the it is casted as one block. And the body directly affected by Heat or chemical or abrasive condition New design the block Geometry is such a way no direct bonding of insulation and PCPB bricks are not available . No direct gas contact with SS Slide plate possible and hence better reliability and life. 6.0 Installation of refractory and refractory In existing Castable design Insulation layer is placed . But since Y type anchors are there to lay insulation is very difficult and the effectiveness of insulation at in situ laying is not good . This also affect life of Slide gate at present. In refractory block design No insulation considered Special interlock arrangement assuring proprietary knowledge and repair need as long as detail geometry drawings are kept confidential. Bricks are not compressed make instead poured into Pre developed mould of specific shape and baked and cured before fixing. The dried pieces are prebaked at a temperature above the maximum temperature to dry the moisture etc. in a way this process eliminates any future crack in the PCPB blocks ( Crack proof. 7.0 Dismantling and repair In situ repair chances are remote as the Castable need to be relaid wit wooden shuttering so the slide plate assembly need to be brought down to ground from an installed height of say 30 m by using a cranes etc . Solid blocks are large and Replacement can only be possible after taking fully the existing or damaged blocks out from The Housing. Again this need cranes as each blocks are heavy and are at 30 M elevation from Ground. In both above existing refixing also need same special cranes etc. HWI new design repair is in situ with in the duct on critical zone mostly come under wear. Due to the geometry selection it is possible to replace same locally . Each zone repair protocol is also a knowledge which is with HWI as part of our Patent. Our blocks are less than 30 Kg weight which is considered as a single person handleable weight in Engineering design. So no need of any heavy cranes simple rope and Chute bags can easily shift new blocks to 30 m level. Repair can be done by a Maison level skilled labor under our guidance with normal foundry tools This ensure Clients to keep low inventory ( only wear zone refractory Repair time and cost get reduced drastically as at present client need to engage heavy cranes to take out slide plate and relining. Or complete refractory block design if damaged need total change for which blocks are expensive. No one so far is using such arrangement in Cement Industry and New Invention is really superior. 8.0 Thermal relative expansion and contraction vis a vis life Castable in situ : not achievable Blocks suspended : achievable as there is no embedded steel inside blocks . But incase if any one is using embedded steel to reinforce bocks it will have to experience relative expansion differential., HWI is not familiar with the core design of Suspended block arrangement Our New Design: Small bricks are overlapping type design wit some gap in between. Since sizes are small the gaps will take good care of forces . Since expansion SS plate is higher than refractory and enough overlap interlocks are available in bricks ensure zero compressive stress element in design. The jacketed cooling of the slide plate and Temperature measurement and insulation layer ensure that the SS Plate expansion / temperature rises can controlled by air flow. Relatively Steel expands 8 times more than the refractory The new invention many ways address this technical issues exist in present on going design concepts. This adds more reliability and life. 9.0 Risk mitigation for high velocity Hot abrasive dust in 20-40% open standard condition of operation in most of the Plants Unknown as the failure with In situ casting is with ion one year. Suspended Block also offer only 2 year life HWI new design expected to have better life due to all other factors mentioned in above 8 points But wear or damage can happen due to abrasion due to high velocity particles in the Gas recirculated through TAD duct But only in critical zone which are exposed .Means on the contact Zone. When plants are operating 30 % open position so the damage directly restricts to 70% of exposed area. This also actual zone where velocity impact in practical limited to bottom edge. This is hardly 10% zone The critical zone refractory blocks can be replaced in situ on in accessible ambient conditions at particular configuration depending on location on the slide plate which also is a special feature of this design. Hence this invention is superior in all means to existing designs. General: Cooling air system : designed to suit the requirement but the components are standard items like Centrifugal Fans and distribution piping etc. But heat exchange requirements are done by Inventors discretion. Drive : Either Linear actuator / winch drive components are standard items available from the market however the size selections etc are done as per design requirement in vew of safety etc by inventor at their discretion. TAD damper housing : Housing is designed by inventor to suit the SS slide gate and PCPB refractory block arrangement and to suit the Duct size and purely at the discretion of the Inventor based on mechanical engineering principles. Conclusion : HWI new design is totally different from all the existing design practices for TAD damper . New Invention addresses advantages over existing design by way of following factors: - With expected more life in respect of traditional method - With less repair cost in terms of time and monitory - With less time and down time of plant. - With less special tools for a replacement construction. - With repair know how with inventor - With mould rights of cast shaped refractory with inventor - The Existing Complete hanging block refractory do not have any comparison with this design conceptually - With more reliability as elaborated in technical write ups. - identifying existing design demerits and addressing concern area in multiple front such as Slide plate design, PCPB Blocks, Therma Expansion conflict, Forced cooling Insulation, fixing arrangement, repair ease etc. - Expecting more life Cycle of operation reliability than existing designs. - Existing designs do not have satisfied Clients including inventors existing design concepts.

Disclaimer: Curated by HT Syndication.