32 results about "Annular duct" patented technology

The invention discloses a directional heat dissipation power distribution cabinet with adjustable air deflectors, which relates to the technical field of equipment for power distribution cabinets and comprises a cabinet body and a heat dissipation unit arranged in the cabinet body. The heat dissipation unit comprises a directional heat dissipation assembly used for carrying out fixed-point jet cooling on key heating elements, an air guide assembly used for optimizing overall airflow organization in the cabinet, and a water cooling assembly used for carrying out pre-cooling on cooling airflow of the directional heat dissipation assembly. The directional heat dissipation assembly comprises a fan at least arranged on the top wall in the cabinet body, an air supply pipe communicated with an outlet of the fan, and an annular air pipe arranged in the power distribution cabinet and communicated with the air supply pipe. Through cooperation of the directional heat dissipation assembly and the water cooling assembly, air blown out of the air blowing pipe at the tail end of the telescopic air column is no longer ambient temperature air but low-temperature cold air cooled in advance through the liquid cooling system. According to the pre-cooling type directional air supply mechanism, the heat dissipation efficiency and the limit capacity of air cooling are greatly improved.

The utility model discloses an annular exhaust device for a pit type heat treatment furnace. The annular exhaust device comprises an exhaust pipeline arranged on a furnace cover, the exhaust pipeline comprises an annular air pipe, an exhaust main pipe rotating section and an exhaust main pipe fixing section which are communicated in sequence; a main support fixed to the ground is arranged on one side of the exhaust pipeline, and the top of the main support supports the exhaust main pipe fixing section. The exhaust main pipe rotating section is connected with the main support through a first rotating connecting mechanism. An air pipe header is arranged between the annular air pipe and the rotating section of the exhaust main pipe, and the air pipe header is connected with the main support through a second rotating connecting mechanism; and the rotating center of the first rotary connecting mechanism, the rotating center of the second rotary connecting mechanism and the rotating shaft of the furnace cover are coaxially arranged. According to the utility model, through symmetrical shunting of the annular air pipe and the rotary connecting mechanism, the exhaust efficiency is improved, the maintenance period is prolonged, the operation process is simplified, and the stability in the synchronous rotating process of the exhaust pipeline and the furnace cover is improved.

The invention discloses a low-altitude high-speed flight manned flying saucer, and relates to the technical field of aviation aircrafts, the low-altitude high-speed flight manned flying saucer comprises a saucer-shaped body, a power device and an undercarriage, the saucer-shaped body is composed of a central bearing ball cabin and a peripheral reinforcing ring coaxially sleeved outside the central bearing ball cabin; the central bearing ball cabin is divided into a celestial navigation and communication cabin, a panoramic cockpit and an environment control and life support system cabin from top to bottom; the inner cabin section of the peripheral reinforcing ring forms a passenger cabin; the bearing strength and the space utilization rate of the machine body are effectively improved through the composite structure of the central spherical cabin and the peripheral reinforcing ring; due to the integrated design of the annular duct and the vector engine, the aerodynamic efficiency and the control flexibility in the vertical take-off and landing and high-speed flight states are remarkably improved; an independent environment control system ensures the safety and comfort of passengers in high-altitude flight; the overall layout gives consideration to functionality and maintenance convenience, and has high practical value.

A heat exchanger positioned within an annular duct of a gas turbine engine is provided. The heat exchanger extends substantially continuously along the circumferential direction and defining a heat exchanger height equal to at least 10% of a duct height. An effective transmission loss (ETL) for the heat exchanger positioned within the annular duct is between 5 decibels and 1 decibels for an operating condition of the gas turbine engine. The heat exchanger includes a heat transfer section defining an acoustic length (Li), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition.

A dual-premixed ammonia burner relates to the field of ammonia combustion equipment. Addressing the problems of high ignition energy, slow combustion speed, poor flame stability, and difficulty in achieving stable combustion in large proportions with ammonia, this invention employs a dual premixing structure of auxiliary fuel gas premixed with ammonia and air premixed with ammonia, combined with a three-stage coaxial air duct and a regenerative pre-combustion chamber to achieve stable combustion. The burner includes an ignition gun, a primary air regulating damper, a secondary air regulating damper, a volute-shaped air casing, a primary air annular duct, swirl vanes, an annular ammonia multi-nozzle header, a pre-combustion chamber, a tertiary air multi-nozzle annular pipe, a flame monitor, and dual ammonia and auxiliary fuel inlets. This invention allows for wide load adjustment from 30% to 100%, no flameout at low loads, high burnout rate, and low nitrogen oxide emissions. It can operate with a large proportion of ammonia or pure gas, features a reasonable structure, reliable ignition, and stable safety, and is suitable for zero-carbon retrofitting and efficient utilization of green ammonia in industrial boilers, kilns, and other thermal equipment.

The utility model relates to the technical field of powder conveying devices, and discloses a powder conveying device for conveying fine particle powder, which comprises a storage bin and a feed port arranged at the top end of the storage bin, and further comprises a spiral powder conveying mechanism fixedly arranged at the discharge end of the storage bin, a dispersion mechanism is arranged at the other end of the discharging pipe and comprises a dispersion bin and an annular air pipe arranged on the outer side of the dispersion bin in a surrounding manner; a dispersion mechanism is arranged in the dispersion bin, and the dispersion mechanism comprises a fixed part fixedly arranged in the dispersion bin; the bottom of the dispersion bin is fixedly connected with a powder outlet pipe, and the bottom end of the powder outlet pipe is fixedly connected with a venturi pipe. According to the powder feeding device for conveying the fine-particle powder, the conveyed powder can be ground and dispersed, powder caking is avoided, the dispersion effect of the fine-particle powder is improved, and the effect of promoting uniform output of the fine-particle powder is achieved.

An apparatus to remove a coating from an edge of a substrate includes a vacuum chuck assembly and a nozzle assembly. The vacuum chuck assembly is configured to support the substrate using suction. The nozzle assembly includes a nozzle head with a pair of nozzle tips configured to direct an angled liquid stream on a surface of the substrate. An annular duct around each nozzle tip discharges a pressurized gas to form a gas shroud around the angled liquid stream.

Turbomachine assembly 10) comprising a centrifugal compressor (11) with a rotor (50) having two impellers arranged in a back-to-back configuration, and a diffuser (12) arranged radially opposite the outlet (13) of the rotor (50) with two impellers, wherein the diffuser (12) comprises means (14) for separating the air exiting the centrifugal compressor (11) arranged such that a first airflow exiting a first impeller (15) feeds a first annular duct (16) of the diffuser (12) and a second airflow exiting a second impeller (17) feeds a second annular duct (18) of the diffuser (12). Abstract figure: Figure 1

The present application belongs to the technical field of pipe belt machine, and particularly relates to a pipe belt machine conveying belt cleaning and water removing device, which comprises a rack, a cross partition plate, a roller set of a pipe belt machine, and a circular tubular conveying belt, and further comprises at least one set of cleaning and water removing devices for cleaning and blowing dry the outer surface of the conveying belt, a through hole door is arranged on the cross partition plate, the cleaning and water removing device comprises a cleaning device and a blowing dry device, the cleaning device comprises a plurality of brush rollers which are matched to form annular surrounding cleaning of the outer surface of the conveying belt, and the two ends of the brush roller are rotatably connected with the cross partition plate through a mounting frame; the blowing dry device comprises an annular air pipe which forms annular surrounding of the outer surface of the conveying belt, the annular air pipe is fixedly connected with the cross partition plate through an air pipe frame, and a plurality of blowing ports are arranged on the pipe wall of the side of the annular air pipe facing the conveying belt; by increasing the cleaning brush roller device and the blowing dry device, water stains on the outer surface of the conveying belt are removed, problems such as slippage and torsion of the conveying belt are avoided, and the stability of the pipe belt machine operation is ensured.

The present application belongs to the technical field of cross-medium unmanned vehicles, and particularly relates to a water-air cross-medium running unmanned vehicle, which forms a smooth transition fluid channel through a hemispherical cover, a cylindrical cabin, an annular duct and a conical bottom cylinder, and solves the problems of low power efficiency, large flow resistance, attitude instability and poor reliability in the prior art. The head part is integrated with a detection and rudder control system, and the open rudder cabin can dynamically adjust the water volume to optimize the center of gravity; the middle part adopts an annular duct integrated constraint propeller flow field to improve water-air thrust efficiency, and the center cabin body is integrated with a core control module; the tail part is convergent design to optimize the fluid trajectory. The modules are quickly and reliably connected through piston sealing and rotary buckles. The present application significantly reduces the cross-medium resistance and water outlet time, ensures the smooth attitude conversion, and greatly improves the maintenance convenience and system reliability due to the modularization and high sealing design, and is suitable for various cross-domain operation scenes such as ocean exploration, emergency search and rescue, etc.

A blower (1) for a fuel cell arrangement for recirculating a volume flow generated during the operation of the fuel cell arrangement is described, wherein the blower comprises a blower duct (2) with an outer wall (2a) extending along a duct axis (A) between a blower duct inlet (2b) and a blower duct outlet (2c) of the blower duct (2), a motor shaft (3) extending through an annular duct section (2d) of the blower duct, a flow guide device (4) arranged adjacent to the blower duct inlet (2b) and configured to impart a swirl to the incoming volume flow, a drain duct (5) with a drain duct opening (5a) arranged in the outer wall (2c) through which liquid can be discharged, and a pressure equalization duct (6) fluidically connected to the drain duct (5) and having a pressure equalization duct opening (6a). exhibitswhich is arranged in the outer wall (2a) and spaced apart from the drain channel opening (5a) along the channel axis (A).

Aircraft turbomachine (10) comprising: - an engine (12), - an annular panel (16) which extends around the engine (12), - a structure (14) for supporting the engine (12), - an annular duct (18) for the flow of a gas flow (F12) between the panel (16) and the structure (14), - a mast (20) for connecting the panel (16) to the structure (14), and - a device (22) for fastening the mast (20) to the panel (16), this device (22) comprising a fitting (24) which is fastened by first screws (26) to the mast (20) and by second screws (28) to the panel (16), the first screws (26) being screwed into nuts (32) which are mounted inside at least one internal cavity (40) of the mast (20), this internal cavity (40) being situated radially at the duct (18).

A heat exchanger positioned within an annular duct of a gas turbine engine is provided. The heat exchanger extends substantially continuously along the circumferential direction and defining a heat exchanger height equal to at least 10% of a duct height. An effective transmission loss (ETL) for the heat exchanger positioned within the annular duct is between 5 decibels and 1 decibels for an operating condition of the gas turbine engine. The heat exchanger includes a heat transfer section defining an acoustic length (Li), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition.

The invention relates to an assembly for a turbine engine, in particular for an aircraft, comprising:-an annular duct having a longitudinal axis through which a first fluid is configured to circulate, and-a heat exchanger (3) arranged in the annular duct, the invention relates to a heat exchanger (1) comprising a longitudinal axis (2) and having a front surface (11) inclined in a main direction (A) with respect to the longitudinal axis, the heat exchanger comprising fins (8) extending transversely between two panels (6, 7) arranged facing each other, the thickness of each of the panels being greater than the thickness of each of the fins. According to the invention, the fins are arranged in a plurality of rows transverse to the main direction, and a portion of the fins is elongated so as to form a first deflector (15) configured such that a first fluid entering the heat exchanger via the front surface deflects in a direction substantially parallel to the direction of extension of the fins.

The invention relates to an aircraft turbomachine subassembly comprising an annular duct (36) extending concentrically about a longitudinal axis and in which an air stream flows from upstream to downstream, the annular duct comprising a duct portion (28) defining a swan neck having an upstream inlet section and a downstream outlet section. A plurality of radial arms (B1, B2) extend circumferentially in the duct portion (28). One or several intermediate walls (P1, P2) extend between two circumferentially adjacent arms (B1, B2) which form a pair of circumferentially adjacent arms among the plurality of circumferentially adjacent arms so as to locally separate, between the two arms of the pair of arms, the annular duct portion (28) into a radially inner portion (Ci) and a radially outer portion (Ce) further away from the longitudinal axis than the radially inner portion.

An apparatus to remove a coating from an edge of a substrate includes a vacuum chuck assembly and a nozzle assembly. The vacuum chuck assembly is configured to support the substrate using suction. The nozzle assembly includes a nozzle head with a pair of nozzle tips configured to direct an angled liquid stream on a surface of the substrate. An annular duct around each nozzle tip discharges a pressurized gas to form a gas shroud around the angled liquid stream.

The utility model belongs to the technical field of cleaning machines, and particularly relates to a cleaning machine blowing structure and a cleaning machine, and the cleaning machine comprises the cleaning machine blowing structure, a shell, an inner container and an air supply mechanism. The cleaning machine blowing structure comprises an annular air pipe, an annular air duct is arranged in the annular air pipe, air inlet pipes are arranged on the two sides of the annular air pipe, each air inlet pipe is provided with an air inlet and an air supply duct, the air inlets of the two air inlet pipes are supported at the opening portions of the corresponding blowing openings, and the air supply ducts are communicated with the annular air duct. A plurality of air outlets are distributed in the top side of the annular air pipe. The air inlet pipes are arranged on the two sides of the annular air pipe, and when the annular air pipe is installed in the inner container of the cleaning machine, the air inlet pipes on the two sides of the annular air pipe support the air blowing opening of the inner container, so that the overall supporting strength is improved, and the problem of instability is avoided. Due to the fact that the two or more air inlet pipes are arranged, two-side air inlet can be achieved, and the problem that air force of an air outlet far away from an air inlet is insufficient is solved.

The utility model relates to the technical field of air bag comb rubber sheet cutting, in particular to a cutting device for air bag comb rubber sheet production, which comprises a vacuum access pipe mounted on a vacuum adsorption table, a moving mechanism arranged on the vacuum adsorption table, a mounting seat mounted on the moving mechanism, and a laser cutting head mounted on the mounting seat. An annular air pipe located on the outer side of the laser cutting head is installed at the bottom of the installation base through a connecting rod, an air inlet pipe is fixedly connected to the annular air pipe, and purging nozzles are installed at the bottom of the annular air pipe in an annular array mode. According to the rubber cutting device, the moving mechanism drives the laser cutting head to move to cut rubber, rubber of any size can be cut according to actual requirements, the universality of the device is improved, high-pressure airflow is guided into the annular air pipe through the air inlet pipe and sprayed out through the purging nozzle while cutting is conducted, melt generated at a cutting point is blown away, and the cutting efficiency is improved. An air cooling barrier is formed in the cutting area, the temperature of the cutting area is reduced, and the thermal shrinkage phenomenon caused by too high rubber temperature at the cutting position is avoided.

The invention discloses a circular array micropore air supply tail end device for a steady-state replacement flow field, and relates to the technical field of air conditioning, the circular array micropore air supply tail end device comprises a plenum chamber type annular pipeline air supply system, a flow equalizing plate, an air inlet pipe, a flow outlet pipe, a flow outlet pipe and an air outlet pipe, and the plenum chamber type annular pipeline air supply system comprises an annular plenum chamber and a flow equalizing plate, the flow equalizing plate is used for realizing conversion from dynamic pressure to static pressure and ensuring uniform distribution of airflow; the fan-shaped efficient air filter is connected to the downstream of the static pressure box type annular pipeline air supply system, the fan-shaped efficient air filter is of a fan-shaped grating-free structure, a filter material of the fan-shaped efficient air filter comprises antibacterial nanometer materials, a frame of the fan-shaped efficient air filter is provided with insertion-pressing type sealing strips, and the design of an annular static pressure box and a flow equalizing structure is beneficial to uniform diffusion of airflow; the combined use of the micropore panel and the adjustable flow guide plate can improve the control performance of the air supply direction; the modularized mounting frame provides convenience for maintenance operation; and the cooperative work of the pressure monitoring and adjusting mechanism is beneficial to maintaining the stability of the device operation.

An annular linear induction pump comprises a casing, an annular duct disposed within the casing, the annular duct having an inner surface and an outer surface, and an electromagnet. The electromagnet can include a center component located within the annular duct and forming the inner surface of the annular duct, a plurality of stators disposed radially around the annular duct, and, a plurality of coils. The annular linear induction pump can be submersible within piping of a nuclear reactor power system.

The utility model relates to the technical field of main shaft starting and stopping, and discloses a high-speed drilling machine main shaft high-speed starting and stopping device which comprises a mounting plate and a motor, a main shaft body is arranged at the output end of the motor, an electromagnetic brake body is fixedly connected to the bottom face of the motor, and a fixing assembly is fixedly connected to the bottom end of the electromagnetic brake body. One end of the fixing assembly is in threaded connection with a limiting column, and one end of the limiting column is fixedly connected with a mounting assembly. According to the high-speed starting and stopping device for the high-speed drilling machine main shaft, through the arrangement of the air cooling assembly, when the high-speed starting and stopping device is used, an air cooling sleeve is installed on an installation suite, when the main shaft body works, a draught fan is started, the draught fan conveys air into an annular air pipe through an output pipe, and the air is blown to the surface of the main shaft body through air holes, so that heat dissipation is conducted on the main shaft body; the main shaft is prevented from generating heat in the high-speed operation process to influence the working state of the main shaft, and the service life of the main shaft is prolonged.

The utility model discloses a kind of smoke exhaust and ventilation device of vertical graphitization furnace, including the smoke outlet of being arranged at the top of preheating zone of furnace body, annular duct and annular duct air hole being arranged at heating zone and high temperature zone of furnace body, and the ventilation pipe being arranged at the cooling and discharging structure of furnace body, the annular duct air hole and ventilation pipe are connected with external gas source respectively.Solution is designed through the annular duct air hole of different position, so that material is not easy to block pipeline, it is beneficial to the uniform distribution of gas, improve the effect of any kind of gas, the setting of air hole directly contacting with material, so that process is simpler, thereby reduce the consumption of gas.

The utility model relates to a kind of combustion boiler furnace device in the field of boiler furnace, including pedestal and support ring, support ring is located on pedestal upside, outer end connection inlet pipe, inner wall installs outlet nozzle, bottom is equipped with limit ring and pedestal upper end insertion joint. Pedestal inner wall installs supporting ring, supporting ring is erected on bucket-shaped inner wall, its bottom side opens blanking port, and periphery is surrounded with annular air pipe, and is connected with air hole. Pedestal outside is equipped with air blower, and is communicated with annular air pipe by air conveying pipe. The device is convenient to disassemble and clean by quick release mechanism, reduces maintenance difficulty;Meanwhile, preheat air in annular air pipe using combustion waste heat, improve air temperature, help natural gas to fire and burn, form good combustion condition, improve combustion efficiency, prolong the service life of device.

A heat exchanger positioned within an annular duct of a gas turbine engine is provided. The heat exchanger extends substantially continuously along the circumferential direction and defining a heat exchanger height equal to at least 10% of a duct height. An effective transmission loss (ETL) for the heat exchanger positioned within the annular duct is between 5 decibels and 1 decibels for an operating condition of the gas turbine engine. The heat exchanger includes a heat transfer section defining an acoustic length (Li), and wherein an Operational Acoustic Reduction Ratio (OARR) is greater than or equal to 0.75 to achieve the ETL at the operating condition.

The utility model discloses a kind of support frame of intercooling system annular pipeline with nylon backing plate, comprising: two support vertical rods, support cross bar, inclined rod, two support plate groups and two base reinforcement plate groups;The outer wall of the upper portion of two support vertical rods is connected with the two ends of support cross bar, the outer wall of the upper portion of a support vertical rod is connected with the upper end of inclined rod, the outer wall of the lower portion of another support vertical rod is connected with the lower end of inclined rod;The lower surface of two support plate groups is installed on the upper end of two support vertical rods, and two base reinforcement plate groups are installed on the outer wall of the lower portion of two support vertical rods;Wherein, each support plate group includes: first plate body, second plate body and third plate body, the lower surface of first plate body is installed on the upper end of support vertical rod, the lower surface of second plate body is installed on the upper surface of first plate body, and the lower surface of third plate body is installed on the upper surface of second plate body.The device is simple in structure, easy and fast to install, and more uniform in stress, more stable in support.

The utility model discloses a constant temperature circulation test box which comprises an outer box body, the inner wall of the outer box body is fixedly connected with an inner box body, the inner wall of the inner box body is rotatably connected with an annular air pipe, and a plurality of air outlet holes are formed in the inner wall of the annular air pipe in an annular array mode. A driving mechanism for driving the annular air pipe to rotate in a reciprocating mode is arranged in a cavity between the outer box body and the inner box body, an air heater and an air cooler are further fixedly installed on the inner wall of the cavity, and the output end of the air heater and the output end of the air cooler are fixedly communicated with the annular air pipe through hoses. The air heater, the air cooler, the annular air pipe and the driving mechanism are arranged, the annular air pipe can rotate in a reciprocating mode through the driving mechanism, the air heater or the air cooler is started in a matched mode, hot air or cold air is blown out through the air outlet holes, and the temperature in the inner box body can be adjusted; therefore, the uniformity of the temperature in the inner box body is facilitated, and the test result is effectively prevented from being influenced by uneven temperature distribution.

The invention belongs to the technical field of cross-medium unmanned aerial vehicles, and particularly relates to a water-air cross-medium operation unmanned aerial vehicle which solves the problems of low power efficiency, large flow resistance, attitude instability and poor reliability in the prior art by forming a fluid channel in smooth transition along a hemispherical cover, a cylindrical cabin, an annular duct and a conical bottom cylinder. The head is integrated with a detection and rudder control system, and an open steering engine room can dynamically adjust the water volume to optimize the gravity center; the middle part adopts an annular duct to integrally restrain a propeller flow field, the water-air thrust efficiency is improved, and a central cabin body is integrated with a core control module; and the tail convergence design optimizes the fluid trajectory. All the modules are quickly and reliably connected through piston seals and rotary buckles. According to the invention, the cross-medium resistance is obviously reduced, the water outlet time is obviously shortened, the stable attitude conversion is ensured, the maintenance convenience and the system reliability are greatly improved due to the modular and high-sealing design, and the system is suitable for various cross-domain operation scenes such as ocean exploration, emergency search and rescue and the like.

The application discloses a kind of viscous iron concentrate shed storehouse automatic identification and processing method, when storehouse is in shed storehouse state, heavy hammer plate is in the natural drooping state under gravity action, heavy hammer plate will contact type switch press into sensor, sensor is in closed state, while detecting plate bottom is not contacted with material, sensor and detecting plate will transmit electric signal to controller, controller will start vibrating device and high-pressure fan, vibrating device vibrates hopper, and support and stirring reinforcement in hopper are vibrated together, eliminate shed storehouse phenomenon, high-pressure fan will high-pressure air be sprayed through air duct, annular air pipe and high-pressure spray head, clean the material adhered and connected on the inner wall surface of hopper, and generate the pressure that material is pushed downward.The device improves the continuity of discharge when in use, reduces the reaction time after the occurrence of shed storehouse phenomenon, eliminates the security risk of manual poking storehouse, improves safety, and the device uses double detection to improve reliability.

The application provides a flow control device and method for improving the efficiency of a ducted fan propulsion, comprising a duct and a ducted propeller device; an annular duct is arranged on the outer periphery of the ducted propeller device; the duct comprises a blowing flow channel, a blowing port, a suction port, a suction flow channel and a gas source device; the blowing port is arranged on the inner surface of the duct, that is, the upper surface of the duct airfoil, and is close to the leading edge of the duct airfoil; the suction port is arranged on the upper surface of the duct airfoil and is away from the leading edge of the duct airfoil; the application introduces a cooperative jet active flow control on the ducted fan, greatly improves the overall propulsion efficiency of the ducted fan, improves the wind resistance of the ducted fan, and enhances the controllability of the ducted fan.

The invention relates to an apparatus for producing a pulverulent product, comprising a device for dropletization (5) of a liquid phase, an addition point (15) for a gas above the device for dropletization (5), at least one gas withdrawal point (19) on the circumference of the apparatus (1), a solid withdrawal point (12) and a tower shell (13) between the device for dropletization (5) and the gas withdrawal point (19) and having, above the solid withdrawal point (12), a region (11) having at least partly a decreasing hydraulic diameter toward the solid withdrawal point (12) and having a maximum hydraulic diameter greater than the mean hydraulic diameter of the tower shell (13), and the tower shell (13) projecting into the region (11) having at least partly a decreasing hydraulic diameter such that an annular duct (23) is formed between the part of the tower shell (13) projecting into the region (11) having at least partly a decreasing hydraulic diameter and the upper part (27) of the region having at least partly a decreasing hydraulic diameter, the at least one gas withdrawal point (19) being disposed in the annular duct (23), wherein the part of the tower shell (13) projecting into the region (11) having at least partly a decreasing hydraulic diameter and forming an inner wall of the annular duct (23) is made at least partly of a gas permeable material (29). The invention further relates to a use of the apparatus (1) for producing pulverulent poly(meth)acrylate.