Improved nozzles for equipment intended for decoking by fluid jet

FIELD: oil and gas industry.

SUBSTANCE: invention is related to equipment intended for tank decoking and may be used for treatment of oil and oil products. The equipment intended for decoking by fluid jets comprises a mechanism for delivery of decoking fluid, a nozzle unit, a cover, at least one cutting nozzle, at least one drilling nozzle and at least one deflector plate for selective orientation of fluid to one of the drilling and cutting nozzles. The fluid delivery mechanism is configured for receipt of pressurized fluid for decoking from the source. There's at least one pipeline for decoking fluid in the cover. The cutting nozzle is made so that selective fluid communication with the pipeline may be created. At least one cutting nozzle is protruded in lateral direction beyond the external dimension set by the cover. Beyond at least one cutting nozzle the major part is not protruded in lateral direction beyond the external dimension set by the cover. The drilling nozzle is made so that selective fluid communication with the pipeline may be created. At least one of cutting nozzles and one of drilling nozzles comprise an inner channel formed between the input and output. The inner channel sets curved conical shape, which is converged along the axial length from input towards output. Upon passage through the fluid flow the flow pattern of decoking fluid at the output from the cutting nozzle and drilling nozzle will be mainly coherent. Radius of the channel cross-section at the input, radius of the channel cross-section at the output and axial length are selected in order to minimize radial velocity and inhomogeneous axial velocity through the minimized axial length.

EFFECT: improving manufacturability, simplifying drilling and improving working efficiency due to possibility of linear conversion in kinetic energy and pressure energy and to facilitation of exact prediction in scaled structures.

8 cl, 5 dwg, 1 tbl

The technical field to which the invention relates.

The invention in General relates to instruments (devices) to remove coke from the tanks, such as coke drums that are used to clean oil and oil products, and more particularly, to improved designs of cutting and drilling nozzles designed for use in the tool toxodontia.

The level of technology

In normal operations, oil refining crude oil is processed into gasoline, diesel fuel, kerosene, lubricants, etc. it is common practice to dispose of heavy residual hydrocarbon by-products due to the process of thermal cracking, known as delayed coking. In the delayed coking of heavy hydrocarbon (oil) is heated to a high temperature (for example, between 900° F and 1000° F) in the large heated heaters, known as blocks distillation, and then transferred to a cylindrical tanks, known as coke drums, which have a diameter of up to 30 feet and a height of 140 feet and is typically performed with the opportunity to work in pairs. From the heated oil are allocated hydrocarbon vapors (including, among other things, gas, naphtha and gas oil)flowing into the base of the distillation unit for processing into useful products, leaving after itself, through the MD combined effect of temperature and storage time, specified solid petroleum coke. This residual coke is necessary to break (to break)to remove it from the tank, which is mainly carried out through the use of the tool for toxodontia (or for cutting coke) in combination with the fluid to toxodontia, such as water under high pressure.

This instrument contains the drill bit with drilling and cutting nozzles. The tool is lowered into the tank through the hole in the upper part of the tank and water under high pressure is injected into the tool, so that it can be selectively directed through the nozzle for drilling or cutting through the nozzle, depending on the operation mode to act as a jet of liquid. Because of the high costs and pressure (for example, the cost of 1000 gallons per minute under a pressure of from 3000 to 4000 pounds per square inch (psi)) is typically used in such operations, it is impractical and undesirable to open drilling nozzle and cutting nozzles simultaneously. Instead predominantly use bypass valves or other flow control device to selectively direction of the fluid to the cutting nozzles or drilling nozzles required in the operation of toxodontia conducted at this time. A couple of examples of tools for toxodontia using the switching of the modes described in U.S. patent 5,16,505 (switch modes manually) and in U.S. patent 6,644,567 (automatic switching). Both of these patents are owned by the assignee of the assignee of the present invention and are incorporated in this description by reference.

Regardless of whether the tool toxodontia characteristics switching or not, the relatively large size of the instrument, which is usually directed outwards cutting nozzles, leads to the fact that it forms a significant radial profile in the reservoir cut coke. The standard instrument has a diameter of about 22 inches and a length of about 35 inches, while the node of the nozzle has a length slightly greater than 5 inches, the outer diameter at the inlet of about 3.75 inches and the external diameter at the outlet of about 1.875 inches. These large sizes increase the tendency of the tool to jam (jam), especially in situations, when formed in the coke aisle can be violated, for example, due to caving of the formation of coke or when the tool gets stuck due to the impact of the pieces of coke formed using fluid to toxodontia produced from the cutting nozzle. In this situation, the tool may become stuck, which requires time and effort for his release.

In addition to the large physical dimensions of standard cutting and drilling nozzles have too much pressure drop. This largely depends on too large a radial profile in the flat the STI outlet for fluid to toxodontia at the top of the nozzle. The standard nozzle is relatively long and has a relatively large radial dimension, so that it is possible to form a large number of drilled channels. Furthermore, the design standard nozzle contains many components which require complex mechanical processing.

It is desirable to create a nozzle for a tool for toxodontia, which will have one or more of the above deficiencies.

Disclosure of inventions

This is done by using the present invention, in which a nozzle for exit of fluid to toxodontia provide improved flow characteristics. The surface of the inner ducts restrict essentially conical or tapering shape, which allows to reduce the radial component of the flow velocity, and similarly reduces the standard deviation of the axial component of the fluid flow to toxodontia. As the standard deviation of the axial velocity is representative of any deviation from the average, it was found that the optimization of the shape of the nozzle (for example, due to the run routine optimization) brings this parameter to a minimum, resulting in receiving the nozzle, which creates a stream in which the flow velocity through the cross section closest to the average value, and is homogeneous the th stream is the most effective for cutting coke in operation toxodontia. Due to these improvements form duct size (in particular, the axial length of the nozzle can be reduced, while still ensuring the necessary impact force of the jet and the coherence of the jet. Such size reduction (as well as reducing the number of parts) improves manufacturability and allows us to simplify the drilling and improve efficiency.

In accordance with the first aspect of the present invention offers the node nozzle for use in a tool for toxodontia using a jet of liquid. The site includes a casing with an educated in its pipeline, which is sufficient for passing the fluid to toxodontia (such as pressurized water) to one or more nozzles, which are fluid-connected with the pipeline. The nozzle includes an inlet for fluid, an outlet for fluid and an internal duct that goes from the inlet nozzle to the outlet nozzle. The duct has a conical shape so that when the fluid to toxodontia passes through the nozzle, the output is created mostly coherent flow regime of the fluid. Such coherence flow achieved through the reduction or elimination of areas of stagnation and large vortex flows. The boundary layer at the wall is also minimized to reduce losses to the turbulence.

Optional, multiple nozzles can be formed in the casing. Such nozzles represent the keys one or more cutting nozzles and one or more drilling nozzles. In a preferred form, a large portion of the nozzle is not acting in the lateral direction beyond the outer size of the casing. In other words, the presence of the nozzle, the node does not lead to a significant expansion or elongation of the casing of the site. Although the precise boundaries of how the nozzle increases the installation space (outer loop) and the dimensions of the casing, are not discussed here, some ranges can be given as an example. For example, in the case of nozzles, which are used in the standard tool for toxodontia (such as the one discussed further in connection with the prior art), the drilling nozzle can extend beyond the size of the full length of the site by 40% or more, while cutting nozzle can play for the full radial dimension or width of 60% or more. These dimensions were significantly more range from approximately 0% to 10%, on which a nozzle in accordance with the present invention can increase the installation space of the casing.

Most of the structures forming the nozzle (including the construction which forms the input, output and intermediate duct formed between input and output)is within (or partially within) the existing structure of the enclosure. Thus, this design is essentially enclosed within the enclosure. This is particularly applicable to cutting nozzles, in which only the edge, see the author with the exit of the nozzle, outside of the casing. Similarly indicated here above, the exact boundaries of how the area of the nozzle or nozzles is beyond the dimensions of the casing, are not discussed here, although some ranges can be given as an example. In the case of nozzles, which are used in the standard tool for toxodontia (such as the one discussed further in connection with the prior art), as drilling and cutting nozzle can have 60% or more design nozzle located outside the casing, while in the case of nozzles in accordance with the present invention, approximately not more than 15% of the length of the cutting nozzles and approximately not more than 25% of the length of the drilling nozzles located outside the casing.

In accordance with the additional options of the nozzle may be fixed relative to the casing so that it cannot rotate or move in any other way, creating a constant cutting angle for cutting nozzles and relatively fixed drilling angle for drilling nozzles. In accordance with another possible variant, the nozzle may have a preparation chamber flow formed directly upstream from the entrance to the fluid. This camera weakens any preliminary turbulence, which occurs as a result of the flow of fluid through the tool body. Has preliminarily the e turbulence is undesirable, because it increases the radial velocity component, when the jet exits the nozzle. The inner duct is mainly optimized to achieve the highest degree of operational characteristics of the nozzle, mainly at least one of the following characteristics: (a) the minimum radial velocity, (b) the minimum non-uniformity of the axial current, and (C) the minimum axial length of the nozzle. In this context, the term "optimization" and its variants specifically refers to the optimization of duct configurations, and this optimization is performed at least by calculating fluid dynamics (CFD)to determine which profile duct allows you to provide the best (or optimal) one or more operating characteristics specified here above. In one form, the CFD process can be used to optimize flow. For example, can be used two profiles nozzles, one of which creates a linear velocity gradient along the length of the nozzle, and the other creates a linear gradient of pressure along the length of the nozzle. This can be represented mathematically in the form of Bezier curves and used as source data for the optimization process. Specialists in this field will easily understand that this can be used, and other mathematical representations in addition to Bezier curves. By changing the pair of the EAN, which form a curve, can be performed multiple runs of the simulation to find the optimal region which satisfies the three mentioned here above criteria.

In accordance with another aspect of the present invention proposes a tool for toxodontia using a jet of liquid. The tool provides a mechanism for feeding fluid to toxodontia that can accept having a pressurized fluid to toxodontia from the source, and the node of the nozzle, which may have fluid communication with the source via this mechanism. In one form of mechanism for feeding fluid to toxodontia has a view of the feed pipe, tube, hose or pipe. The site includes a casing with one or more pipelines for fluid to toxodontia formed therein, and includes one or more cutting nozzles and one or more drilling nozzles. The cover may be a separate structure that can be attached to the tool body for toxodontia (e.g., using fasteners, friction fit or other suitable means), or the casing may be part of a tool body, for example, made as a single whole with him. In the other situation, it is likely that the maximum lateral (or radial) plot size tool toxodontia, which come in is through the tank to toxodontia, will be limited to housing site (with nozzles). Each of the drilling and cutting nozzles can be selective fluid communication with the pipeline into the body of the instrument. The valve or its associated mechanism reject stream, which is located in the channels formed between the nozzles and piping in the body of the instrument, allows for selective direction of the fluid to toxodontia through the casing, so that, during specific operations of cutting or specific drilling operations, the nozzle or nozzles, which in this operation is not used, the fluid is disconnected from the source. Moreover, the nozzle may include an inner duct having a conical shape, so that when the passage of fluid to toxodontia through the nozzle, the flow regime of the fluid to toxodontia when it exits from the nozzle is a mostly coherent flow mode.

In a more specific form of tool for toxodontia valves work with a device to switch modes, which directs fluid to toxodontia in drilling or cutting nozzle. In another possible embodiment, one or more nozzles are arranged inside the tool toxodontia, so much of the design of the nozzle is located within the outer contour (footprint) of the tool body. This reduces due with what was eating at least a radially outer projection tool. As before, the design of the unit ensures that a large part of the profile of the nozzle was sealed inside the body of the tool, so that the outlet nozzle is entirely or almost entirely located inside the outer dimensions of the tool. In accordance with another possible option is a big part of the at least one cutting nozzle is not acting in the lateral direction beyond the outer dimensions of the housing of the tool for toxodontia. More specifically, this greater part of the nozzle can be essentially all of the nozzle. The node may be so designed that one or more nozzles is fixed relative to the tool body and the nozzle of the specific form contains a preparation chamber flow formed directly upstream from the entrance for fluid and has a fluid communication with the pipeline. As in the previous aspect, the inner duct is mainly optimized to achieve one or more characteristics selected from the group comprising: (a) the minimum radial velocity, (b) the minimum non-uniformity of the axial current, and (C) the minimum axial length of the nozzle.

In accordance with another aspect of the present invention proposes a method of transmission fluid for toxodontia through the nozzle. The method involves the selection of the configuration of the at least one nozzle for transmission of the specified vial the IDA for toxodontia through it, and the specified at least one nozzle includes an inner duct having a conical shape. Furthermore, the method provides for the flow of fluid to toxodontia at least one nozzle, so that after passing through the flow regime of the fluid to toxodontia is mostly coherent.

Optionally, the method further provides for the transmission fluid to toxodontia at least one drilling nozzle and at least one cutting nozzle. The method may additionally provide for selective direction of the fluid to toxodontia through the cutting nozzle or drilling the nozzle at any given time. Such selective direction in General can be achieved by using the device mode and, more specifically, through the use of automatic switching, which uses changes in the pressure of the fluid to toxodontia to switch between cutting and mode of drilling. In the specific form of the method involves the computation of CFD in the design of the nozzle, with special attention given to the design flow nozzle in accordance with the CFD calculation. The calculation in the design of the nozzle in accordance with the present invention allows for one or more x is the new, selected from the group comprising: (a) the minimum radial velocity, (b) the minimum non-uniformity of the axial current, and (C) the shortest possible axial length of the nozzle. In another possible form can be used in the preparation chamber of the flow to reduce or eliminate any pre-swirl, which may result from the flow of fluid through the tool body.

These and other features of the invention will be more apparent from the subsequent detailed description, given with reference to the accompanying drawings, in which similar parts have the same reference designators.

Brief description of drawings

Figure 1 shows a view in section of a combination tool for cutting coke and device switching in accordance with the prior art.

Figure 2 shows in detail the site of the nozzle of the instrument shown in figure 1.

Figure 3 shows in detail the internal duct of one of the nozzles of the tool and the site shown respectively in figures 1 and 2.

Figure 4 shows in detail the site of a nozzle in accordance with an aspect of the present invention.

Figure 5 shows in detail the internal duct of one of the nozzles in accordance with the present invention.

Refer first to a consideration of figure 1, which shows a standard tool 1 glycocholate with protective drilling blades or vanes 3 and the device 4 switch modes, a built-in tool 1. The device 4 switch modes contains many components, including the housing 4A, the sleeve 4B of the actuator, the groove 4C of the actuator, the pin 4D of the actuator, the spring 4E, entrance 4F pressurized fluid, an annular cylinder 4G, the annular piston 4H, holder studs 41 of the actuator and the liner 4J, which surrounds the lower portion 6B of the control lever 6, which also includes the upper portion 6A. The control lever 6 is connected to the hydraulic distribution plate (also called a deflector plate) 5, so that when the device 4 switch modes trigger, manual, or by sequential increase and decrease of pressure fluid from a source of fluid (not shown), then the control lever 6 rotates the deflector plate 5, which makes holes formed in its axial direction, alternately open pipe 7 for feeding the drilling nozzle 10 or the cutting nozzle 11 of the fluid under high pressure (e.g., water) through the inlet pipe or drill rod 9. In the variant shown in figure 1, the drilling nozzles 10 have fluid communication with a source of pressurized fluid to be directed generally downward flow of fluid under high pressure in the coke (not p is the cauldron), what will be drilled the hole for the rest of the device 4. In General, a flat deflector plate 5 in the form of a disk mounted to rotate and connected with the control lever 6, allows switching between cutting and mode of drilling through periodic synchronized rotation of the deflecting plate 5. Details of the construction and operation of the deflecting plate 5 there is not further discussed, it is enough to say that such details are described in U.S. patent 6,644,567.

We now turn to a consideration of figure 2 and 3, which shows the drilling nozzle 10 and the cutting nozzle 11 in accordance with the prior art, and the node that contains the nozzle 10 and 11, also includes a casing H, which has a radial size R and the axial dimension A. you Can see that drilling nozzle 10 extend in the axial direction for a considerable distance beyond the axial dimension, while cutting nozzle 11 extend in the radial direction for a considerable distance beyond the radial dimension of R. moreover, these nozzles 10 and 11 contain a number of separate tubes or channels, which allow you to isolate the respective fluid streams from each other at considerable length of the nozzle. Cutting nozzle 11 (which has the same characteristics as a drilling nozzle 10) has an input 11A in the air stream and exit 11, moreover, it is also shown separate ducts 11B, 11C and 11D in the form of concentric tubes which are bundled "straws cocktail" or combined in any other well-known layout. You can see that all the individual ducts of the drained fluid for toxodontia into a common header 11TH, and flow while moving towards the exit 11F has a change of direction at an acute angle. Such abrupt changes can create friction, turbulence and other anomalies that can affect the characteristics of the flow through the nozzle 11. These anomalies can be enhanced due to the flow separation, which may occur in the area of the gap formed in the linear nozzle (also called insert 11G nozzle), which is formed by the fluid upstream from the critical section, where the collector 11TH meets exit 11F. All these factors can lead to a reduction of the axial component of the flow as it exits from the nozzle N at the output 11F. Figure 3 shows the three main parts of the site, forming a cutting nozzle 11, and air conditioning 11A, the linear nozzle 11G and the cover 11N casing used in Association with ducts 11B, 11C and 11D, the common collector 11TH and output 11F, to direct the flow of pressurized water. Linear nozzle 11G collects the flow from the air conditioner 11A and accelerates its exit 11F, which may be subjected to fur the systematic processing to change the output area (coefficient of discharge) of the nozzle. Cover 11N casing creates a reinforced border pressure and additionally combines conditioning 11A flow and resistant to erosion insert 11G nozzle.

We now turn to a consideration of figure 4 and 5, which shows the characteristics associated with the node 100 and the nozzles 110, 111 in accordance with the present invention. The node 100 includes a casing H, which contains the pipe 107A, B, which acts as fluid passages for supplying fluid to toxodontia, which comes from a pressurized source (not shown) in the drilling nozzle 110 and the cutting nozzle 111. In particular, figure 5 shows the cutting nozzle 111, however, it should be borne in mind that the design shown here and duct equally applicable to drilling the nozzle 110. Unlike standard duct shown in figure 3, the inner surface shown in figure 5, may have an essentially conical tapering form street 111A, which is optimal for spraying fluid to toxodontia and obtained using a CFD calculation to achieve the minimum radial velocity and the minimum non-uniformity of the axial flow, with the shortest possible length of the nozzle. It was found that by optimizing the nozzle as it was shown for coke cutting operations, get more columnar, coherent thread because the radial component of velocity of the flow is minimized. Due to such improvements in the form of a duct, the size of the nozzles 110, 111 compared to the nozzles 10, 11 in figure 2 and 3 (especially their axial dimension can be reduced, while still ensuring the necessary impact force of the jet and the coherence of the jet. This reduction in size (as well as reducing the number of parts) improves manufacturability and allows you to simplify drilling, partially due to the smaller profile of the drilling holes. Were used CFD simulation and bench testing to optimize the shape of the inner duct street 111A in accordance with the specific use of the tool for toxodontia and its operating conditions. Due to the reduction or elimination of areas of stagnation and large vortex flow duct nozzle can maintain a high degree of coherence of the stream.

We now turn to a consideration of figure 5 while accessing data of Table 1, which also shows the shape and dimensions of the internal water passages for cutting nozzles 111. It should be borne in mind that the characteristics described below for cutting nozzles 111, equally applicable to the drilling nozzle 110 and therefore, the two times are not repeated. Table 1 shows a representative X and Y dimensions of the surface of the inner duct nozzle made in accordance with the present invention, when was used CFD algorithm.

By reducing the pressure drop that occurs in the standard nozzle, nozzle 110, 111, manufactured in accordance with the present invention, have a shorter axial dimension and the associated lower the required installation space for the node 100 of the nozzle that allows you to set the nozzle in a confined space. For example, in situations when there is a collapse of the reservoir, a new having a smaller node 100 nozzles in the first place retracts back into the body, allowing you to get more streamlined shape, which can often be applied directly to the public is pulled from the collapsed reservoir. In addition, this configuration allows to save energy and potentially allows the use of pump and motor of lower power, as a similar volume of fluid and its velocity at the exit of the nozzles 110, 111 can be achieved with less pumping. Moreover, the new node 100 of the nozzle contains two items of a smaller size, easier and cheaper to produce.

CFD and related algorithms modeling, as well as bench testing can be used to create a desired configuration of the duct for fluid to toxodontia. Specialists in this field will readily understand that the main CFD package can be developed specifically for the present invention, or available in finished form trade code can be used for the implementation discussed here, the CFD analyses. CFD modeling can be used to locate specific characteristics of the stream, such as a coherent flow, laminar or turbulent flow of the locations in which you can expect flow separation, etc. In particular, CFD can be used to model specific internal structures (ducts) of the nozzle, such as a unique profile of nozzles in accordance with the present invention. Such calculation methods can take into account the specific hydraulic characteristics flew the Yes to toxodontia. Can also be used iterative approaches for studying the effects of disturbance of the flow and to optimize the configuration of the inner duct. Such iteration can be based on simple source geometries (such as tubular elements, simple cones and other easily defined configuration), which can then be modified to obtain the desired flow characteristics (such as linear pressure drop along the flow axis). The optimization parameters may include minimization of the radial inflow at the critical section of the nozzle and the standard deviation of the axial flow velocity (which provide for the expense of uniform flow through the critical section of the nozzle). An additional advantage that the resulting geometry is that you can use well-known similarity laws for the implementation of the scale, depending on the required size of the node 100. Thus, the nozzle can be made for different flows and pressures within limited fully developed turbulent flow, the importance of which is that it allows a linear transformation of the kinetic energy and the energy of the pressure that facilitates accurate prediction scaled structures.

Despite the fact that have been described are preferred in the ways of carrying out the invention, it should be borne in mind that they are illustrative of the invention, and it is quite clear that it specialists in this field can be amended and supplemented, which do not extend, however, beyond the scope of the following claims.

1. Tool for toxodontia using a jet of liquid, which contains:
the mechanism of fluid supply to toxodontia configured to receive pressurized fluid for toxodontia from the source;
node nozzle, the liquid associated with the specified feeder fluid toxodontia, and the specified node nozzle contains:
the casing containing therein at least one conduit for liquid to toxodontia;
at least one cutting nozzle is made with the possibility of creating selective fluid communication with the specified pipeline, and the specified at least one cutting nozzle protrudes in the lateral direction beyond the outer size of the set specified by the casing, and the majority of the specified at least one cutting nozzle is not acting in the lateral direction beyond the outer dimension defined by the specified casing; and
at least one drilling nozzle made with the possibility of creating selective fluid communication with the specified pipe; and at least one of the decrees of the data at least one cutting nozzle and the specified at least one drilling nozzle has an internal duct, formed between the inlet and outlet, and an internal duct defines a curved conical shape that converges along the axial length from the specified input to the specified output, so that after passing through the specified liquid toxodontia the flow regime specified fluid toxodontia when you exit the program from the specified at least one cutting nozzle and the specified at least one drilling nozzle will be mostly coherent, and the radius of the cross section of the duct at the inlet, the radius of the cross section of the duct at the outlet and the axial length is selected in such a way as to minimize the radial velocity and the heterogeneity of the axial velocity through minimized axial length; and
at least one deflector plate for selective direction of fluid toxodontia to one of the specified at least one of cutting and drilling nozzles, so that in this mode, when the specified at least one cutting nozzle has a fluid connection with the specified source of the specified at least one drilling nozzle liquid disconnected from the specified source, and in this mode, when the specified at least one drilling nozzle has a fluid connection with the specified source of the specified at least one cutting nozzle liquid disconnected otokonoko source.

2. The tool according to claim 1, which further comprises a switching device modes, which depends on changes in fluid pressure for toxodontia, so that in the first working mode of the specified device mode interacts with the specified tool toxodontia and the specified fluid toxodontia to set the drilling mode using said at least one drilling nozzle, while in the second operating mode, the specified device mode interacts with the specified tool toxodontia and fluid toxodontia to set the cutting conditions using said at least one cutting nozzle.

3. The tool according to claim 1, wherein said casing and the specified at least one cutting nozzle specify the width of the specified node of the nozzle, so that the specified at least one cutting nozzle increases specified width relative to the width of the specified cover is not more than approximately 10%.

4. The tool according to claim 3, in which less than about 15% of the length of the specified at least one cutting nozzle protrudes in the lateral direction for a given external size of the specified cover.

5. The tool of claim 1, wherein the specified at least one cutting nozzle is essentially fixed relative to the casing shown.

6. The tool according to claim 1, which further comprises the preparation chamber of the flow formed directly upstream from the specified input to the liquid and having liquid communication with the specified pipeline.

7. The tool according to claim 1, in which less than about 25% of the length of the specified at least one drilling nozzle is located outside of the enclosure.

8. The tool according to claim 1, wherein said inner duct has an input radius of the specified input to the specified internal duct, which is about 3 times more output radius of the specified output specified internal duct.