JPH07126632A - Apparatus for confirming attachment or detachment of oven door of coke oven and confirmation method - Google Patents

Abstract

PURPOSE:To provide an apparatus for confirming the attachment or detachment of an oven door of a coke oven and a confirmation method capable of realizing the reliability of each operation and promoting the automation of a traveling machine of a coke oven in the confirmation of the attachment or detachment of an oven door using a distance-measuring means such as an optical sensor attached to a traveling machine of a coke oven. CONSTITUTION:The distance between an operation mechanism part of a lifter and the oven door of a coke oven varies by the steps of the attaching and detaching operation of an oven door. Taking note of this phenomenon, the confirmation apparatus is provided with a distance-measuring means 21 capable of measuring the distance to the object site to be detected and with a controlling means to transfer the apparatus to the next operation step when the distance measured by the distance-measuring means 21 falls within the range of optimum standard distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace lid attachment / detachment confirmation apparatus and a furnace lid attachment / detachment confirmation method for a coke oven, and particularly measures the distance between the oven lid and the oven lid for each step of the attachment / detachment operation. The present invention relates to a furnace lid attachment / detachment confirmation device and a furnace lid attachment / detachment confirmation method for a coke oven.

[0002]

2. Description of the Related Art It has been proposed to use an air sensor to automatically confirm the attachment / detachment state of a furnace lid in the work of attaching / detaching the furnace lid of a coke oven.

An outline will be given based on FIG. FIG. 19 is a plan view of a main part of the conventional coke oven 1 when the furnace lid 3 is attached to and detached from the furnace port 2. In the coke oven 1, a pair of hook receiving hardware 4 is projected, and in the furnace lid 3, a hook 5 engaging with the hook receiving hardware 4,
A lug piece 6 for lifting the furnace lid 3 is provided.

A lifter hook detachment machine (lifter) 7 in a coke oven moving machine that can run along the coke oven 1 is provided with a lifter hook 8 and a furnace lid attachment / detachment confirmation mechanism 9.

The lifter hook 8 engages from below the lug piece 6 to lift and hang it.

The furnace lid attachment / detachment confirmation mechanism 9 is provided with a pair of air sensors 10, and the air sensors 10 are opposed to the detection site 11 of the sac 5 and air is jetted to the detection site 11 to reflect the back pressure of the reflection. In response, the attachment / detachment of Kannuki 5 can be detected.

That is, the air sensor 10 is attached to the front side of the lifter frame 12 of the lifter 7 in the furnace. The line back pressure generated when the air ejected from the tip of the nozzle of the air sensor 10 hits the detected portion 11 is converted into an electric signal by the air / electric converter 13 to measure the distance between them, or By checking the presence / absence of the presence or absence, it is confirmed whether or not the furnace lid 3 is “wearing” or “disengaging”.

However, in the furnace lid attachment / detachment confirmation mechanism 9 having such a configuration, the detection distance of the air sensor 10 is limited to a maximum of 30 mm, and the furnace body of the coke oven 1, the furnace lid 3, the lifter 7 and other moving machines are limited. There is a problem that it may not be possible to perform measurement in response to a change (increase / decrease) in the detection distance due to a change over time or a change in temperature.

That is, the furnace lid 3 is deformed due to aging or thermal deformation, and the knife edge 14 attached to the furnace lid 3 needs to be adjusted. Further, the lifter hook 8 and the lug piece 6 are worn out due to wear.

Therefore, the distance between the lifter frame 12 or the lifter hook 8 and the hood 5 of the furnace lid 3 is not uniform in each kiln, and these distances are 40 to 50 m.
Some of them are m, and there is a problem that it is impossible to detect the distance by the air sensor 10 or identify the presence or absence of the blank 5.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an optical device installed in a coke extruder, a guide car, a furnace lid desorption machine (lifter) or the like in a coke oven moving machine. When confirming the attachment / detachment of the furnace lid using a distance measuring device such as a linear sensor, the reliability of each operation can be ensured by measuring the distance between the furnace lid and the furnace lid for each step of the furnace lid attachment / detachment operation. An object of the present invention is to provide a furnace lid attachment / detachment confirmation device and a furnace lid attachment / detachment confirmation method of a coke oven that can be realized and promote automation of a coke oven moving machine.

[0012]

That is, according to the present invention, the distance between the operation mechanism portion of the coke oven moving machine and the oven lid of the coke oven is different in each step of the operation of attaching and detaching the oven lid. Focusing on the change, the first invention is a coke oven furnace lid attachment / detachment confirmation device for confirming whether or not the oven lid of the coke oven is securely attached to and detached from the oven mouth. Along with attaching to a lifter to be detached and attached, a distance measuring means capable of measuring a distance between the furnace lid and a detected portion, and storing a range of respective appropriate reference distances in respective steps of the operation of attaching and detaching the furnace lid, A device for confirming attachment / detachment of a furnace lid of a coke oven, comprising: a control unit that controls the process to shift to the next operation step when the distance measured by the distance measuring unit is within the range of the appropriate reference distance. so That.

The distance measuring means may be an optical sensor.

Further, the distance measuring means may measure a distance between the furnace lid and a detected portion provided on the hood.

A second aspect of the present invention is a coke oven furnace lid attachment / detachment confirmation method for confirming whether or not the oven lid of the coke oven is surely attached / detached to / from the furnace mouth. And the distance between each of the proper reference distances in each step of the furnace lid desorption operation is stored, and when the distance measured by the distance measuring means is within the range of the proper reference distance. The method for confirming the attachment / detachment of the furnace lid of the coke oven is characterized by controlling so as to shift to the next operation step.

Each step of the "removing" operation of the furnace lid is as follows.
The process may include a lifter hook hooking process of the furnace lid lifter, a lifter spring pressing process, and a lifter lifting process.

Further, each step of the "wearing" operation of the furnace lid is as follows.
It may include a lifter suspending step of the lifter of the furnace lid, a lifter spring returning step, and a lifter hook removing step.

[0018]

In the apparatus and the method for confirming the attachment / detachment of the oven lid of the coke oven according to the present invention, the distance between the lifter and the oven lid of the coke oven is different in each step of the attachment / detachment operation of the oven lid. For example, each process of the “remove” operation of the furnace lid includes a lifter hook hanging process of the lifter of the furnace lid, a lifter spring pushing process, and a lifter lifting process, and each process of the “mounting” operation of the furnace lid. Is, since it includes a lifter suspending step of the lifter of the furnace lid, a lifter spring returning step, and a lifter hook removing step,
If the range of the appropriate reference distance in each process is set and each measured distance falls within this range, it is judged that the posture of the furnace lid or the relative positional relationship with the lifter is appropriate. Since I moved to the operation of
It is possible to surely execute each process.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a furnace lid attachment / detachment confirmation device and a furnace lid attachment / detachment confirmation method for a coke oven according to an embodiment of the present invention will be described with reference to the drawings. However, the same parts as those in FIG. 19 are designated by the same reference numerals, and the detailed description thereof will be omitted.

FIG. 1 shows a device 20 for confirming attachment / detachment of a furnace lid of a coke oven.
2 is a side view of the lifter frame 12 in which the optical sensor 21 (distance measuring means) such as a laser sensor is located at a position where the lifter frame 12 of the lifter 7 faces the canvas 5. When installing, light /
A control circuit 22 including an electric converter is provided. The lifter 7 is capable of turning around the turning axis 7A.

The control circuit 22 stores the range of the proper reference distance in each step of the detaching operation of the furnace lid 3, and when the distance measured by the optical sensor 21 is within the range of the proper reference distance, The control is performed so as to shift to the next operation step (described later).

FIG. 3 is a front view of the oven lid 3 of the coke oven 1 as seen from the front, and FIG. 4 is a side view of the main portion of the oven lid 3. As shown in FIG. 11 is provided.

As shown in FIG. 4, the spring-pressing cylinder 2 is provided at a portion of the lifter 7 facing the cannuki 5.
3, and a lifter hook cylinder 24 for moving the lifter hook 8 up and down.

FIG. 5 shows a device 20 for confirming the attachment / detachment of the oven lid of the coke oven.
FIG. 3 is a plan view of a main part of the portion, in which an optical sensor 21 is attached to a lifter frame 12 of a lifter 7 and is opposed to a detected portion 11 of a strip 5;

As shown in FIG. 5, the hook 5 has a hook spring 25 for pressing the spring 23.
It is biased in the direction, and the protruding part 5A of Kannuki 5
Engages with the stopper portion 3A of the furnace lid 3 to integrate the hook 5 with the furnace lid 3.

Next, the steps particularly related to the operation for confirming the attachment / detachment of the furnace lid of the present invention will be described with reference to FIGS. 6 and 7. FIG. 6 is a flow chart showing the operation process of “removing” the furnace lid 3, and FIG. 7 is a flowchart showing the operation process of “wearing” the furnace lid 3.

That is, as shown in FIG. 6, first, the lifter 7 is swung around its swivel axis 7A (FIG. 2),
The lifter hook 8 and the optical sensor 21 are brought into a state of being opposed to the lug piece 6 of the furnace lid 3 and the snail 5 (detection site 11), respectively (step S1).

Then, the lifter 7 is advanced toward the furnace lid 3 so that the lifter hook 8 is located immediately below the lug piece 6 (step S2). The operation up to this point is to perform the posture control of the lifter 7 itself, which is a pre-stage of the control according to the present invention.

Next, the lifter hook cylinder 24
To lift the lifter hook 8 by driving
The lifter hook 8 hooks the lug piece 6 (step S3).

Here, the lifter spring pushing operation is performed (step S4). That is, by driving the spring-pressing cylinder 23, the cannuki 5 is pushed in the direction of the coke oven 1 against the biasing force of the canne spring 25, and the lifter hook 8 is returned so as to be separated from the coke oven 1 to lift the lifter hook. The engaging surface 8 </ b> A of 8 abuts on the lug piece 6 to ensure that the lifter hook 8 holds the lug piece 6.

Finally, the lifter hook cylinder 24
Is further driven to lift the furnace lid 3 (step S5).

Next, when the furnace lid 3 is "worn", as shown in FIG.
The lifter hook 8 and the optical sensor 21 by rotating the lug piece 6 of the furnace lid 3 around the rotation axis 7A.
Then, it is made to be in a state of being opposed to Kannuki 5 (detection site 11), respectively (step S11).

Then, the lifter 7 is advanced toward the furnace lid 3 so that the furnace lid 3 faces the position of the furnace opening 2 (step S1).
2). The operation up to this point is to perform the posture control of the lifter 7 itself, which is a pre-stage of the control according to the present invention.

Next, the lifter hook cylinder 24
The lifter hook 8 is lowered together with the furnace lid 3 by releasing the drive of, that is, the lifter is hung,
The hook 5 is hooked on the hook receiver 4 (step S13).

Here, the lifter spring returning operation is performed (step S14). That is, the spring pressing cylinder 23
By releasing the drive of the cannuki spring 25, the cannuki 5 is slightly pulled back from the coke oven 1 direction by the urging force of the cannuki spring 25, and the lug piece 6 is pulled from the engaging surface 8A of the lifter hook 8.
Should be slightly separated.

Finally, the lifter hook cylinder 24
By further canceling the driving of (3), the lifter hook 8 is removed from the lug piece 6 of the furnace lid 3 (step S15).

FIG. 8 schematically shows the relative positional relationship among the furnace lid 3, the hook 5, the lug piece 6, the lifter hook 8 and the spring pressing cylinder 23 in such a series of operations. The upper part of FIG. 6 shows the state before the spring is pushed in step S4 in FIG. 6, that is, the hooking state in step S3, and the lower part of the figure shows the state after the spring is pushed. However, in order to make it easy to understand the correlation between the respective parts, the canvas 5 (plan view state) and the lug piece 6 (side view state) are drawn so as to be on the same plane with each other rotated by 90 degrees.

As shown in FIG. 8, the interval between each part of the lifter 7 and each part of the coke oven 1 or the furnace lid 3 is set to a predetermined value. For example, a clearance A1 between the hook receiving bracket 4 and the hook 5, a clearance A2 between the hook 5 and the spring pressing cylinder 23, a clearance A3 between the engaging surface 8A of the lifter hook 8 and the lug piece 6, a furnace, The withdrawal amount A4 of the lid 3 and the stroke A5 of the spring pressing cylinder 23 are set in advance.

However, as described above, the secular change and the temperature change of the coke oven 1 and the oven lid 3, the wear of the lifter hook 8 and the lug piece 6, the looseness in the lifter 7, the wear of the knife edge 14, and the hook-up. Clearances A1 and A due to variations in 5
2, A3, etc. may deviate from the set values, which reduces the reliability of the work for confirming the attachment / detachment of the furnace lid 3, but the present invention allows the attachment / detachment of the furnace lid 3 even if such a deviation occurs. Made sure that the confirmation can be performed.

FIGS. 9 to 12 are schematic views of the snap receiver 4 in each operation step described in FIGS. 6 to 8.
The relative relationship among the canvas 5, the lug piece 6, the lifter hook 8, the spring pressing cylinder 23, and the forward end metal fitting 26 is shown more clearly. The upper part of each figure shows the canvas 5.
Plane view of the relative position between the spring pressing cylinder 23 and the spring pressing cylinder 23, and an intermediate part is a side explanatory view of the relative position of the spring receiving cylinder 4 and the hook receiving bracket 4.
And the lower part is a side view of the relative position of the lug piece 6 and the lifter hook 8.

First, FIG. 9 shows the state of the forward end of the lifter at step S2 of FIG. 6, in which the forward end metal 26 of the lifter 7 is brought into contact with the cannuki 5 which is engaged with the cannuke receiving metal 4, so that the spring 5 and the spring are connected. A gap C1 is opened between the pushing cylinder 23 and a gap C2 between the engagement surface 8A of the lifter hook 8 and the lug piece 6.

FIG. 10 shows a hooked state in step S3 of FIG. 6, showing a state where the lifter hook 8 is raised and engaged with the lug piece 6.

FIG. 11 shows the state in which the spring is pressed in step S4 of FIG. 6, and the interval C3 is provided between the sack 5 and the forward end hardware 26, and between the inner end surface 4A of the slat receiver metal piece 4 and the slat 5. A space C3 of the same size is opened, and the space C1 between the sleeve 5 and the spring pressing cylinder 23 is
And the above-mentioned interval C2 between the engaging surface 8A of the lifter hook 8 and the lug piece 6 becomes zero.

FIG. 12 shows a state in which the lifter is lifted up in step S5 of FIG. 6, between the cannuki 5 and the advancing end hardware 26 and between the inner end surface 4A of the cannuke receiving hardware 4 and the cannula 5.
While maintaining the space C3 between the and, the space C4 in the height direction is opened between the canvas receiving hardware 4 and the canvas 5, and the lug piece 6 is lifted up by the same height as the space C4.

Confirmation work of the attachment / detachment of the furnace lid 3 in the steps of various operations relating to the furnace lid 3 by the lifter 7 as described above will be described with reference to FIGS. 13 to 18.

FIGS. 13 to 15 show the operation steps of the “removing” of the furnace lid 3 in order, and FIGS. 16 to 18 show the operation steps of the “wearing” of the furnace lid 3 in order. The relative positional relationship among the cannuki 5, the lug piece 6, the lifter hook 8 and the optical sensor 21 is shown.

FIG. 13 shows a state in which the hooking in step S3 of FIG. 6 is completed, and if the measured distance X1 between the optical sensor 21 and the snap ring 5 is within the range of the predetermined proper reference distance, the hooking is performed. The control circuit 22 (FIG. 1) determines that the hooking is completed, and shifts to the lifter spring pressing in the next step S4.

That is, the inner end surface 4 of the cannula receiver 4
When the set distance between A and the optical sensor 21 is L and the allowable value is α1, if | X1−L | ≦ α1, then the sleeve 5 is within the proper range in the receiving portion of the sleeve receiving member 4. Judge that it is set to the position.

FIG. 14 shows a state in which the lifter spring pushing in step S4 of FIG. 6 is completed. If the measured distance X2 between the optical sensor 21 and the cannula 5 is within a predetermined proper reference distance, the spring is pressed. When it is determined that the pushing has been completed, the process proceeds to the lifting of the lifter in the next step S5.

That is, the inner end portion 4 of the cannuki receiving member 4
When the distance between A and the spring-loaded spring 5 is m and the allowable value is β1, if | X2− (L + m) | ≦ β1, the spring 5 is the inner end surface 4A of the spring receiver 4.
And the lug piece 6 moves to an appropriate position on the hook receiving bracket 4 while the lug piece 6 is engaged with the engaging surface 8 of the lifter hook 8.
It is determined that A has been engaged.

FIG. 15 shows a state in which the lifting of the lifter in step S5 of FIG. 6 is completed, and the measurement distance X3 between the optical sensor 21 and the snail 5 cannot be obtained, that is, the snail 5 is placed on the snail receiver 4. If not, it is determined that the lifting of the lifter is completed, and the operation proceeds to the next.

FIG. 16 shows a state in which the lifting of the lifter in step S13 of FIG. 7 is completed. If the measured distance X4 between the optical sensor 21 and the cannula 5 is within a predetermined proper reference distance, When it is determined that the lifter suspension has been completed, the process proceeds to the lifter spring return of the next step S14.

That is, when the allowable value is β2, |
If X4− (L + m) | ≦ β2, it is determined that the pipe 5 is located on the furnace port 2 side from the inner end surface 4A of the pipe receiving metal 4 and is fitted in the proper position on the pipe receiving metal 4.

FIG. 17 shows a state in which the lifter spring return of step S14 of FIG. 7 is completed, and the optical sensor 21
If the measured distance X5 between the lock lever 5 and the hook 5 is within the range of the predetermined proper reference distance, it is determined that the lifter spring return is completed, and the process proceeds to the hook removal in the next step S15.

That is, when the allowable value is α2, |
If X5-L | ≦ α2, it is determined that the hook 5 is set in a position within the proper range of the hook receiving metal member 4 and the lifter hook 8 can be removed from the lug piece 6.

FIG. 18 shows a state in which the hook removal in step S15 of FIG. 7 is completed, and the measured distance X5 between the optical sensor 21 and the latch 5 is within a predetermined proper reference distance (| X5-L │ ≦ α2) is being monitored, the lifter hook 8 is lowered, and the hook 5 is engaged with the hook receiving member 4, that is, the furnace lid 3 is set in the coke oven 1. , The engagement between the lug piece 6 and the lifter hook 8 is released.

The above-mentioned allowable values α1, α2, β1, β
In No. 2, this may be arbitrarily set, and may be updated according to the secular change of the coke oven 1 and others.

As described above, in each operation step associated with the attachment / detachment of the furnace lid 3, the distance between the furnace 5 and the cannuki 5 is measured, and if this measured value is within the range of the appropriate reference distance,
It is determined that the positions of the valve 5 and the furnace lid 3 in the process are proper, and the process moves to the next operation process.

In this embodiment, the optical sensor 21 is used in place of the conventional fixed air sensor 10 and this is used as a detection device (distance measuring means). The detection distance can be made long by simply replacing the dynamic sensor 21, and the sensor 5 and the sensor 5 of the furnace lid 3 which is the detected portion can be made longer.
Even if the distance between 1 and 1 varies due to secular change or the like, the influence on the detection accuracy is almost eliminated.

[0060]

As described above, according to the present invention, an optical sensor or the like is used as the distance measuring means, and it is determined whether or not the measured distance is within an appropriate range, and the process proceeds to the next operation step. Therefore, it is possible to improve the detection accuracy and contribute to the automation of the work around the coke oven moving machine.

[0061]

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a positional relationship of a furnace lid attachment / detachment confirmation device 20 of a coke oven according to an embodiment of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is a front view of the furnace lid 3 of the coke oven 1 seen from the front.

FIG. 4 is a side view of the main part of the same.

FIG. 5 is a plan view of an essential part of a furnace lid attachment / detachment confirmation device 20 of the same.

FIG. 6 is a flowchart showing an operation process of “remove” the furnace lid 3 in the same manner.

FIG. 7 is a flow chart showing an operation process of “wearing” the furnace lid 3 in the same manner.

FIG. 8 is a cross-sectional explanatory view schematically showing the relative positional relationship among the furnace lid 3, the hook 5, the lug piece 6, the lifter hook 8 and the spring pressing cylinder 23 in a series of operations for attaching and detaching the furnace lid 3. .

9 is an explanatory diagram showing a state of a lifter forward end in step S2 of FIG.

FIG. 10 is an explanatory diagram showing a hooked state in step S3 of FIG. 6;

11 is an explanatory diagram showing a state of spring pressing in step S4 of FIG.

FIG. 12 is an explanatory view showing a state of lifting the lifter in step S5 of FIG.

FIG. 13 is an explanatory diagram showing a state where hooking in step S3 of FIG. 6 is completed.

FIG. 14 is an explanatory diagram showing a state where pushing of the lifter spring in step S4 of FIG. 6 is completed.

FIG. 15 is an explanatory diagram showing a state where lifting of the lifter in step S5 of FIG. 6 is completed.

16 is an explanatory diagram showing a state where suspension of the lifter in step S13 of FIG. 7 is completed.

FIG. 17 is an explanatory diagram showing a state where the lifter spring return of step S14 of FIG. 7 is completed.

FIG. 18 is an explanatory diagram showing a state where the hook removal in step S15 of FIG. 7 is completed.

FIG. 19 is a plan view of a main part of the conventional coke oven 1 when the furnace lid 3 is attached to and detached from the furnace opening 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coke oven 2 Furnace opening 3 Furnace lid 3A Stopper part of furnace lid 3 4 Kannuki metal receiver 4A Inner end surface of Kannuki hardware 4 4A 5 Kannuki 5A Kannuki 5 protrusion 6 Lug piece 7 Lifter (roof lid removal machine) (coke oven 7A Swivel axis of lifter 7 8 Lifter hook 8A Engagement surface of lifter hook 8 Furnace lid attachment / detachment confirmation mechanism 10 Air sensor 11 Detected part 12 Lifter frame 13 Air / electric converter 14 Knife edge 20 Coke oven Furnace lid attachment / detachment confirmation device 21 Optical sensor (distance measuring means) 22 Control circuit including optical / electrical converter 23 Cylinder for spring pushing 24 Cylinder for lifter hook 25 Kannuki spring 26 Forward end hardware

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Honma 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. Chome (No house number) Kawasaki Steel Co., Ltd. Mizushima Steel Works

Claims (6)

[Claims] 1. A coke oven attachment / detachment confirmation device for confirming whether or not the oven lid of the coke oven is surely attached / detached to / from the oven mouth, wherein the oven lid is attached to a lifter to be attached / detached, and The distance measuring means capable of measuring the distance to the detected part and the range of the appropriate reference distance in each step of the operation of attaching and detaching the furnace lid are stored, and the distance measured by the distance measuring means is the appropriate reference. A furnace lid attachment / detachment confirmation device for a coke oven, comprising: a control unit that controls to shift to the next operation step when the distance is within the range. 2. The oven lid attachment / detachment confirmation device for a coke oven according to claim 1, wherein the distance measuring means is an optical sensor. 3. The apparatus for confirming attachment / detachment of a furnace lid of a coke oven according to claim 1, wherein the distance measuring unit measures a distance between the furnace lid and a detected portion provided on the hearth. 4. A method for confirming the attachment / detachment of a coke oven lid, which confirms whether or not the oven lid of the coke oven is securely attached / detached to / from the furnace opening, the method comprising: The distance is measured, and the range of the appropriate reference distance in each step of the operation of attaching and detaching the furnace lid is stored, and when the distance measured by the distance measuring means is within the range of the appropriate reference distance, the next operation is performed. A method for confirming the attachment / detachment of a furnace lid of a coke oven, which is characterized by controlling so as to shift to a process. 5. Each step of the “remove” operation of the furnace lid includes a lifter hook hooking step of a lifter of the furnace lid, a lifter spring pushing step, and a lifter lifting step. How to confirm the attachment / detachment of the oven lid of the coke oven described. 6. Each step of the “attaching” operation of the furnace lid includes a lifter suspending step of a lifter of the furnace lid, a lifter spring returning step, and a lifter hook removing step. The method for checking the attachment / detachment of the coke oven lid described in 4.