CN211471484U

CN211471484U - Roller-hearth heat treatment furnace

Info

Publication number: CN211471484U
Application number: CN201922324714.9U
Authority: CN
Inventors: 罗侠; 江华; 王珂; 赵云飞; 杨三堂
Original assignee: Ceri Phoenix Industrial Furnace Co ltd; MCC Capital Engineering and Research Incorporation Ltd
Current assignee: Ceri Phoenix Industrial Furnace Co ltd; MCC Capital Engineering and Research Incorporation Ltd
Priority date: 2019-12-23
Filing date: 2019-12-23
Publication date: 2020-09-11
Anticipated expiration: 2029-12-23

Abstract

The utility model discloses a roller hearth type heat treatment furnace, including furnace body, interior roll table, burning system and the burning monitored control system of discharging fume, the furnace body contains from the top furnace roof, furnace wall and the stove bottom that connects gradually down, with one side be equipped with in the furnace wall and follow a plurality of burner ports and the exhaust port that ejection of compact direction interval set up, burning system of discharging fume contains confession row trunk line and edge a plurality of burning units of discharging fume that ejection of compact direction interval set up, the burning unit of discharging fume contains nozzle (2), heat exchanger (3), gas supply branch line (11), combustion air supply branch line (12) and branch line (13) of discharging fume, the plug-in of nozzle (2) matching in the burner port, the plug-in that heat exchanger (3) matches in the exhaust port. The roller hearth type heat treatment furnace has the advantages of uniform furnace temperature, high air preheating temperature, low energy consumption and less investment. Is particularly suitable for the heat treatment of thick plates and has the advantage that the traditional roller-hearth heat treatment furnace can not be substituted.

Description

Roller-hearth heat treatment furnace

Technical Field

The utility model relates to the field of heat treatment equipment, in particular to a roller hearth type heat treatment furnace.

Background

Traditional roller hearth heat treatment furnace adopts nozzle and preheater as an organic whole usually, and combustion air and gas realize abundant burning at the multistage mixture of nozzle inner passage, form longer flame shape, and the flue gas is discharged by nozzle outer loop channel, is equipped with fin convection type air heater in the outer loop channel of nozzle, carries out the heat exchange with the flue gas, retrieves the waste heat. The roller-hearth heat treatment furnace with the heat supply and smoke exhaust integrated nozzles is adopted, and the nozzles are arranged in a staggered mode in the furnace length direction, so that the temperature uniformity of the steel plate is guaranteed. 10-15 temperature control sections are arranged along the length direction of the furnace, and each section is provided with 2 thermocouples for detecting the temperature.

The burner is integrated with the preheater, so that the volume of the preheater is limited, the air preheating temperature is low, and the energy-saving effect is poor; because the heat supply and the smoke discharge are at the same position, the flame is easy to be short-circuited, and is directly discharged from the flue without entering the hearth, thereby wasting energy; in addition, each temperature control section is only provided with two thermocouples, and the furnace temperature cannot be accurately controlled.

SUMMERY OF THE UTILITY MODEL

In order to improve energy-conserving effect, the utility model provides a roller-hearth heat treatment furnace, this roller-hearth heat treatment furnace adopt split type setting with nozzle and heat exchanger, and this roller-hearth heat treatment furnace's advantage is that the furnace temperature is even, the air preheating temperature is high, the energy consumption is low, and the investment is less, is particularly suitable for the open fire thermal treatment of thick plate.

The utility model provides a technical scheme that its technical problem adopted is: a roller hearth type heat treatment furnace comprises a furnace body, a roller way in the furnace, a combustion smoke exhaust system and a combustion monitoring system, wherein the furnace body comprises a furnace lining refractory material layer and an outer steel structure which are sleeved with each other, the roller way in the furnace body comprises a plurality of furnace rollers which are arranged at intervals along a discharging direction, the furnace body comprises a furnace top, a furnace wall and a furnace bottom which are sequentially connected from top to bottom, a plurality of combustion ports and smoke exhaust ports which are arranged at intervals along the discharging direction are arranged in the furnace wall on the same side, the combustion ports are arranged below the furnace rollers, the smoke exhaust ports are arranged above the furnace rollers, the combustion smoke exhaust system comprises a main supply and exhaust pipeline and a plurality of combustion smoke exhaust units which are arranged at intervals along the discharging direction, each combustion smoke exhaust unit comprises a burner, a heat exchanger, a fuel gas supply branch line, a combustion air supply branch line and a smoke exhaust branch line, and an insert piece, the plug-in components that the heat exchanger matches are in the smoke evacuation mouth, supply and exhaust trunk line can be to burning smoke evacuation unit supply gas and with the flue gas in the burning smoke evacuation unit is discharged, and this burning monitored control system can detect the temperature and the pressure in the furnace.

The both ends of furnace body all are equipped with furnace gate, furnace gate elevating gear and furnace gate closing device, and the both ends of stove roller are passed through aligning roller bearing and bearing frame and are connected with the outside steel construction, roller hearth heat treatment furnace still includes roll table actuating mechanism, roll table actuating mechanism contains frequency conversion gear motor and indirect shaft coupling.

The inboard of furnace gate is equipped with sealed curtain, and sealed curtain is refractory fiber cloth and the flexible integrated configuration who hangs stainless steel net, and the furnace wall refractory material layer of furnace roller top is refractory fiber modular structure, and the furnace wall refractory material layer of furnace roller below is the structure of laying bricks.

The outside steel construction is formed by the steel welding, and the inboard surface of furnace gate is equipped with light-duty fire resistant fiber structure, and the inside of furnace gate is equipped with water-cooling structure, furnace gate elevating gear is electric lift structure, furnace gate closing device is pneumatic compact structure.

The burner is located under the heat exchanger, the burner and the furnace roller are arranged alternately along the discharging direction, the lower part in the furnace body is provided with a flow guide wall, the flow guide wall and the burner are located on two opposite sides of the furnace body, and the flow guide wall can guide hot air to move upwards.

The main supply and exhaust pipeline comprises a main gas supply pipeline, a main combustion air supply pipeline and a main exhaust pipeline, the main gas supply pipeline is connected with a gas interface of the burner through a branch gas supply line, the main combustion air supply pipeline is connected with a combustion-supporting gas inlet of the heat exchanger through a branch combustion air supply line, a combustion-supporting gas outlet of the heat exchanger is connected with a combustion-supporting gas interface of the burner through a branch connection line, and the main exhaust pipeline is connected with a flue gas outlet of the heat exchanger through a branch exhaust line.

The gas supply branch line is sequentially provided with a manual ball valve, a first electromagnetic valve and a first manual gate valve, and the combustion air supply branch line is sequentially provided with a second electromagnetic valve and a second manual gate valve.

The combustion monitoring system comprises a plurality of thermocouples and pressure gauges, wherein the thermocouples are connected with the temperature measuring holes in a one-to-one correspondence manner, and the pressure gauges are connected with the pressure measuring holes in a one-to-one correspondence manner.

The utility model has the advantages that:

1. the burners are arranged in the gap of the roller way in the furnace of the roller hearth type heat treatment furnace, the burners and the flue are configured in pairs on the upper side and the lower side of the furnace wall, the guide walls, the sectional partition walls and the full furnace burners are arranged in a staggered mode in a sectional mode, pulse combustion control is combined, flames are effectively organized, and temperature uniformity in the width direction of the furnace is guaranteed.

2. Each burner corresponds to a thermocouple and is combined with a digital pulse control system, so that extremely flexible heat supply partition is realized in control, the combustion state of each burner can be effectively controlled, and accurate furnace temperature control can be realized. Specifically, the division of the heat supply area is determined according to the arrangement condition of the thermocouples, and the heat supply areas with the same number can be divided by more thermocouples without increasing any cost.

3. The upper hearth does not have a burner, so that the installation space and the combustion space of the burner are not required to be met, and the upper hearth is lower in height and less in investment than the traditional roller hearth furnace.

4. The size of the preheater in the flue can be adjusted according to the preheating temperature, so the temperature of the preheated air is higher and reaches more than 500 ℃, meanwhile, most refractory materials of the furnace body adopt refractory fiber modules with good heat insulation effect, the heat dissipation loss is less, and the heat efficiency of the furnace is high.

5. Can meet the heat treatment requirement of high-end thick plates and has very important significance for improving the product competitiveness of enterprises.

Drawings

The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a front view of a roller hearth heat treatment furnace according to the present invention.

Fig. 2 is a sectional view taken along a-a in fig. 1.

Fig. 3 is a partial sectional view taken along the direction G-G in fig. 1.

FIG. 4 is a schematic view of a combustion smoke evacuation system.

Fig. 5 is a schematic view of a heat exchanger.

1. A furnace roller; 2. burning a nozzle; 3. a heat exchanger; 4. a guide wall; 5. a thermocouple; 6. an outer steel structure; 7. a furnace lining refractory material layer; 8. a sealing curtain; 9. a furnace door; 10. a segmental partition wall; 11. a gas supply branch line; 12. a combustion air supply branch line; 13. a smoke exhaust branch line; 14. a main gas supply line; 15. a combustion air supply main line; 16. a main exhaust pipeline; 17. the branches are connected.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

The utility model provides a roller hearth type heat treatment furnace, includes furnace body, interior roll table, burning system of discharging fume and burning monitored control system, the furnace body contains the furnace lining refractory material layer 7 and the outside steel construction 6 that the endotheca was established, the interior roll table of furnace is located in the furnace body, the interior roll table of furnace contains along ejection of compact direction F (be the steel sheet advancing direction in the stove) many furnace rollers 1 that set up at interval, the furnace body contains from the top down connected gradually furnace roof, furnace wall and stove bottom, with one side be equipped with in the furnace wall along a plurality of burner ports and the exhaust port that the ejection of compact direction F interval set up, this burner port is located the below of furnace roller 1, this exhaust port is located the top of furnace roller 1, burning system of discharging fume contains confession trunk line and follows the ejection of compact direction interval set up a plurality of burning unit of discharging fume, burning unit of discharging fume contains nozzle 2, heat exchanger 3, The combustion-supporting air supply branch line 12 and the smoke exhaust branch line 13 are connected in series, the burner 2 is matched with a plug-in unit in the burner, the heat exchanger 3 is matched with a plug-in unit in the smoke exhaust port, the main supply and exhaust pipe can supply gas to the combustion smoke exhaust unit and exhaust smoke in the combustion smoke exhaust unit, and the combustion monitoring system can detect temperature and pressure in a hearth, as shown in fig. 1 to 5.

In this embodiment, both ends of the furnace body are provided with a furnace door 9, a furnace door lifting device and a furnace door pressing device, the furnace door lifting device can lift the furnace door 9, and the furnace door pressing device can press the furnace body by the furnace door 9. The two ends of the furnace roller 1 are connected with an outer steel structure 6 through a self-aligning roller bearing and a bearing seat, the roller hearth type heat treatment furnace further comprises a roller way driving mechanism, and the roller way driving mechanism comprises a variable-frequency speed reducing motor and an intermediate coupling shaft coupling.

The roller hearth type heat treatment furnace also comprises a charging roller way, a discharging roller way, a centering device, a brush roller and other mechanisms, and mainly realizes the functions of positioning, surface cleaning and conveying of the steel plate. All roller ways are driven by a variable frequency speed reducing motor and an intermediate shaft coupling, the roller way structure in the furnace is formed by welding and combining a heat-resistant steel hollow roller body and shaft heads at two ends, self-aligning roller bearings are arranged on the shafts at two ends of the furnace roller 1, and bearing seats are arranged at the positions of supports on the steel structure 6 at the outer side.

In this embodiment, the furnace body can be divided into a furnace lining refractory material layer 7 and an outer side steel structure 6 in the order from inside to outside, and the furnace body can be divided into a furnace top, a furnace wall and a furnace bottom which are connected in sequence from top to bottom. The outside steel construction 6 is placed on the concrete foundation, and the inboard of furnace gate 9 is equipped with sealed curtain 8, and sealed curtain 8 is the integrated configuration of refractory fiber cloth and flexible stainless steel net of hanging, and sealed curtain 8 plays the furnace gate when opening and seals the burner gas, reduces calorific loss's effect.

The furnace lining refractory material layer 7 above the furnace roller 1 is of a refractory fiber module structure, and consists of alumina silicate refractory fiber modules with different service temperatures and different thicknesses and a back lining alumina silicate refractory fiber blanket according to different heat treatment temperatures, and the working surface is the alumina silicate refractory fiber module.

The furnace lining refractory material layer 7 below the furnace roller 1 is of a bricklaying structure. The refractory brick consists of various refractory bricks, heat insulating bricks and hard alumina silicate refractory fiber products, and the working surface is made of refractory bricks. The furnace lining refractory material mainly plays a role in protection and heat insulation, and reduces the temperature of the wall of the chamber furnace under the high-temperature state in the furnace, thereby improving the operating environment of the furnace area. The positions of the full furnace burner and the smoke outlet are divided into 4 sections in a staggered manner along the furnace length direction, partition walls are arranged at the furnace bottom and the furnace top at the boundary of each section, and a guide wall is built on the furnace wall opposite to the burner, so that the flow of smoke in the furnace is improved, and the temperature uniformity of steel plates is guaranteed.

In the present embodiment, the outer steel structure 6 is formed by welding steel materials. Specifically, the outer steel structure 6 is formed by welding various section steels (channel steel, i-steel, angle steel, H-section steel) and steel plates of various thicknesses, and is divided into a furnace top steel structure, a side steel structure, a furnace bottom steel structure and an end steel structure, and the upper four parts form 1 rectangular frame structure. The steel structure mainly plays a role in supporting lining refractory materials, various furnace equipment (furnace doors, burners and the like) and operation platforms, pipelines and the like outside the furnace, and is a framework of the whole roller hearth furnace.

In this embodiment, the two furnace doors 9 are respectively a charging furnace door and a discharging furnace door, the inner side surface of the furnace door 9 is provided with a light refractory fiber structure, the inside of the furnace door 9 is provided with a water cooling structure, the furnace door lifting device is an electric lifting structure, and the furnace door pressing device is a pneumatic pressing structure.

The furnace door 9 is formed by combining various section steels and steel plates, and the inner lining adopts a light refractory fiber structure and a water cooling structure; furnace gate elevating system: the automatic opening and closing device is used for automatically opening and closing the furnace door during charging and discharging and adopts an electric lifting mode; after the furnace door is closed, the furnace door is compressed by the pneumatic pressing device, so that the overflow of high-temperature flue gas in the furnace and the suction of external cold air can be effectively prevented.

In this embodiment, nozzle 2 is located heat exchanger 3 directly below, and nozzle 2 and stove roller 1 are followed the ejection of compact direction is arranged in turn, the lower part in the furnace body is equipped with guiding wall 4, and guiding wall 4 is located with nozzle 2 the relative both sides of furnace body, and guiding wall 4 can lead hot air upwards to move.

In this embodiment, the main supply and exhaust pipeline includes a main gas supply pipeline 14, a main combustion air supply pipeline 15 and a main exhaust pipeline 16, the main gas supply pipeline 14 is connected to the gas interface of the burner 2 through a branch gas supply line 11, the main combustion air supply pipeline 15 is connected to the combustion-supporting gas inlet B of the heat exchanger 3 through a branch combustion air supply line 12, the combustion-supporting gas outlet C of the heat exchanger 3 is connected to the combustion-supporting gas interface of the burner 2 through a branch connection line 17, and the main exhaust pipeline 16 is connected to the flue gas outlet D of the heat exchanger 3 through a branch exhaust line 13.

The lower single-side burner is adopted for supplying heat, the upper part of the same side is used for discharging smoke, and a mode of recovering waste heat by using a preheater in the smoke pipe is adopted. The burners and the smoke pipes are arranged in pairs on the same side of the upper part and the lower part of the furnace wall, the burners are subjected to multi-stage mixed combustion through air and gas, high-speed combustion products are sprayed into the furnace from the lower side of the furnace wall, and after flowing through the lower surface and the upper surface of the steel plate, smoke is discharged out of the furnace after being subjected to heat exchange through the preheater in the flue. The burner 2 adopts a sub-high-speed burner and is provided with a burner controller, and a set of electromagnetic valve and a manual valve are respectively arranged on a gas pipeline and a combustion air pipeline of each burner, so that pulse combustion can be realized, and the uniformity of the furnace temperature is ensured.

Specifically, gas and combustion-supporting air are mixed and combusted in the burner 2 and flame is sprayed into a hearth, the structure of the heat exchanger 3 is roughly shown in fig. 5, the heat exchanger 3 comprises an inner cavity and an outer cavity, a flue gas inlet E of the heat exchanger 3 and a flue gas outlet D of the heat exchanger 3 are both communicated with the inner cavity, a combustion-supporting gas inlet B of the heat exchanger 3 and a combustion-supporting gas outlet C of the heat exchanger 3 are both communicated with the outer cavity, and high-temperature flue gas in the hearth can enter the inner cavity to heat the combustion-supporting air in the outer cavity, as shown in fig. 3 to 5.

The gas supply branch line 11 is sequentially provided with a manual ball valve, a first electromagnetic valve and a first manual gate valve, and the combustion air supply branch line 12 is sequentially provided with a second electromagnetic valve and a second manual gate valve. The gas supply main pipeline 14, the combustion air supply main pipeline 15 and the smoke exhaust main pipeline 16 are respectively provided with a fan, the fans adopt variable frequency motors, and the suction force of the fans is changed by adjusting the frequency of the motors to control the pressure of the hearth.

In this embodiment, a plurality of temperature measuring holes are arranged in the furnace top, three pressure measuring holes are arranged in the furnace top, the plurality of temperature measuring holes and the three pressure measuring holes are arranged at intervals along the discharging direction, the combustion monitoring system comprises a plurality of thermocouples 5 and pressure measuring instruments, the thermocouples 5 are connected with the temperature measuring holes in a one-to-one correspondence manner, the thermocouples 5 and the furnace rollers 1 are alternately arranged along the discharging direction F, and the pressure measuring instruments are connected with the pressure measuring holes in a one-to-one correspondence manner.

The combustion monitoring system consists of a detection element, control software and control hardware. The detection element comprises a thermocouple 5 for measuring the temperature of the furnace and an infrared thermometer for measuring the temperature of the steel plate; a pressure transmitter (i.e., a load cell) that measures the furnace pressure; a residual oxygen analyzer for measuring the oxygen content in the flue gas; a laser detector for measuring the position of the steel plate, a motor encoder and the like. The control software comprises temperature control, furnace pressure control, flow control, PLC control and the like.

The utility model adopts the above combustion and smoke exhaust design, furnace gas well-circulating furnace shape structure to combine pulse digital combustion control technology, can make the steel sheet heating temperature even in the roller hearth type heat treatment furnace, satisfy corresponding heat treatment requirement, energy consumption low, the small investment.

The operation of the roller hearth heat treatment furnace will be described below.

The steel plate is centered and positioned outside the furnace, the steel plate is conveyed into a hearth of the roller-hearth heat treatment furnace by the furnace roller 1, a charging furnace door is closed, a combustion medium in the burner 2 is combusted, and the generated flue gas flows through the lower surface of the steel plate, the flow guide wall 4, the upper surface of the steel plate, enters a flue gas inlet E of the heat exchanger 3 and is discharged out of a factory building by a flue gas exhaust fan. The heat of the flue gas heats the steel plate and preheats combustion air.

Each thermocouple 5 corresponds to one set of burner 2 and heat exchanger 3, and the working state of the burner can be grasped and adjusted through the temperature feedback of the thermocouple 5, so that the complete combustion of a combustion medium is ensured. The digital pulse control system controls different distributions of heat supply of the administered subareas by controlling the opening time sequences of the gas electromagnetic valve and the air electromagnetic valve and combining the feedback of the thermocouple 5, thereby realizing the optimal combination of the thermocouple and the burner, namely, the elastic subarea.

The above description is only for the specific embodiments of the present invention, and the scope of the present invention can not be limited by the embodiments, so that the replacement of the equivalent components or the equivalent changes and modifications made according to the protection scope of the present invention should still belong to the scope covered by the present patent. In addition, the utility model provides an between technical feature and the technical feature, between technical feature and technical scheme, technical scheme and the technical scheme all can the independent assortment use.

Claims

1. The utility model provides a roller hearth heat treatment furnace, a serial communication port, roller hearth heat treatment furnace includes furnace body, interior roll table, burning system and the burning monitored control system of discharging fume in the stove, the furnace body contains furnace wall refractory material layer (7) and outside steel construction (6) that the endotheca was established, the roll table is located in the furnace body in the stove, the roll table contains many stove rollers (1) that set up along ejection of compact direction interval in the stove, the furnace body contains from last furnace roof, furnace wall and the stove bottom that connects gradually down, with one side be equipped with in the furnace wall along a plurality of burner ports and the exhaust port that ejection of compact direction interval set up, this burner port is located the below of stove roller (1), and this exhaust port is located the top of stove roller (1), burning system of discharging fume contains and supplies row trunk line and follows a plurality of burning units of discharging fume that ejection of compact direction interval set up, the unit of discharging fume contains nozzle, The combustion monitoring system comprises a heat exchanger (3), a fuel gas supply branch line (11), a combustion air supply branch line (12) and a smoke exhaust branch line (13), wherein a burner (2) is matched with an insert in a combustion port, the heat exchanger (3) is matched with an insert in the smoke exhaust port, the fuel gas supply and exhaust main pipe can supply fuel gas to the combustion smoke exhaust unit and exhaust smoke in the combustion smoke exhaust unit, and the combustion monitoring system can detect the temperature and the pressure in a hearth.

2. The roller hearth heat treatment furnace according to claim 1, wherein the furnace body is provided with a furnace door (9), a furnace door lifting device and a furnace door pressing device at two ends, the two ends of the furnace roller (1) are connected with the outer steel structure (6) through a self-aligning roller bearing and a bearing seat, the roller hearth heat treatment furnace further comprises a roller way driving mechanism, and the roller way driving mechanism comprises a variable-frequency speed-reducing motor and an intermediate shaft coupling.

3. The roller hearth heat treatment furnace according to claim 2, wherein the inner side of the furnace door (9) is provided with a sealing curtain (8), the sealing curtain (8) is a combined structure of refractory fiber cloth and a flexible hanging stainless steel wire mesh, the lining refractory material layer (7) above the furnace roller (1) is of a refractory fiber module structure, and the lining refractory material layer (7) below the furnace roller (1) is of a bricklaying structure.

4. The roller hearth heat treatment furnace according to claim 2, wherein the outer steel structure (6) is welded by steel, the inner surface of the furnace door (9) is provided with a light refractory fiber structure, the interior of the furnace door (9) is provided with a water cooling structure, the furnace door lifting device is an electric lifting structure, and the furnace door pressing device is a pneumatic pressing structure.

5. The roller hearth heat treatment furnace according to claim 1, wherein the burners (2) are located right below the heat exchanger (3), the burners (2) and the furnace rollers (1) are alternately arranged along the discharging direction, a guide wall (4) is arranged at the lower part in the furnace body, the guide wall (4) and the burners (2) are located at two opposite sides of the furnace body, and the guide wall (4) can guide hot air to move upwards.

6. A roller hearth heat treatment furnace according to claim 1, wherein the main supply and exhaust pipe comprises a main gas supply line (14), a main combustion air supply line (15) and a main exhaust pipe line (16), the main gas supply line (14) is connected with a gas interface of the burner (2) through a branch gas supply line (11), the main combustion air supply line (15) is connected with a combustion-supporting gas inlet of the heat exchanger (3) through a branch combustion-supporting gas supply line (12), a combustion-supporting gas outlet of the heat exchanger (3) is connected with a combustion-supporting gas interface of the burner (2) through a branch connection line (17), and the main exhaust pipe line (16) is connected with a flue gas outlet of the heat exchanger (3) through a branch exhaust pipe line (13).

7. A roller hearth heat treatment furnace according to claim 6, wherein the gas supply branch line (11) is provided with a manual ball valve, a first solenoid valve and a first manual gate valve in this order, and the combustion air supply branch line (12) is provided with a second solenoid valve and a second manual gate valve in this order.

8. The roller hearth heat treatment furnace according to claim 1, wherein a plurality of temperature measuring holes are provided in the furnace top, three pressure measuring holes are provided in the furnace top, the plurality of temperature measuring holes and the three pressure measuring holes are arranged at intervals along the discharging direction, the combustion monitoring system comprises a plurality of thermocouples (5) and pressure measuring instruments, the thermocouples (5) are connected with the temperature measuring holes in a one-to-one correspondence manner, and the pressure measuring instruments are connected with the pressure measuring holes in a one-to-one correspondence manner.