Title of Invention	METHOD FOR MEASUREMENT OF FLOW IN GAS LINE USING IMPROVED FLOW TRANSMITTER IMPULSE LINE SYSTEM
Abstract	Thus the main object of the present invention is to provide a totally safe drainage system for accumulated water from the impulse line. Another object of the present invention is to reduce the time required to drain out the accumulated water. Yet another object of the invention is to reduce the manpower requirement as only one person can do the job safely. These and other objects of the invention can be achieved by providing a pair of small drift pots and a pair of additional drain valves in both the impulse lines. Thus the present invention provides a flow transmitter impulse line for safe drainage of accumulated water from said impulse line, comprising: a positive and negative impulse line connected to either side of an orifice plate in a gas line; a flow transmitter connected to said impulse line through a manifold unit; and drain valves connected to each of said impulse lines for draining out the water from the impulse lines; wherein a pair of drain valves are provided in each line with a draft pot provided between each pair of drain valves for draining out accumulated water from the impulse lines in auto mode.

Title of Invention

METHOD FOR MEASUREMENT OF FLOW IN GAS LINE USING IMPROVED FLOW TRANSMITTER IMPULSE LINE SYSTEM

Abstract

Thus the main object of the present invention is to provide a totally safe drainage system for accumulated water from the impulse line. Another object of the present invention is to reduce the time required to drain out the accumulated water. Yet another object of the invention is to reduce the manpower requirement as only one person can do the job safely. These and other objects of the invention can be achieved by providing a pair of small drift pots and a pair of additional drain valves in both the impulse lines. Thus the present invention provides a flow transmitter impulse line for safe drainage of accumulated water from said impulse line, comprising: a positive and negative impulse line connected to either side of an orifice plate in a gas line; a flow transmitter connected to said impulse line through a manifold unit; and drain valves connected to each of said impulse lines for draining out the water from the impulse lines; wherein a pair of drain valves are provided in each line with a draft pot provided between each pair of drain valves for draining out accumulated water from the impulse lines in auto mode.

Full Text	-2- FIELD OF APPLICATION The present invention relates to a flow transmitter impulse line for safe drainage of accumulated water from the impulse line. BACKGROUND OF THE INVENTION The flow in the impulse system is proportional to square root of differential pressure iewhere Q = flow, k = constant, P1 = pressure before orifice, P2 = pressure after orifice plate. This differential pressure is tapped and transmitted through a tube and connected to a differentia! pressure transmitter and this tube further extended and connected with a drain valve. In a flow impulse system the impulse line is a transmission media in which differential pressure is transferred to flow transmitter, this is usually made of high quality steel tube and the diameter varies from 10 to 25 mm. To collect differential pressure across the orifice plate this impulse line is used. A drain valve is used for purging or draining of impulse line. -3- A manifold unit is used for equalizing pressure across the transmitter. This is a safety device for transmitter, used during calibration, removing or fixing of transmitter. The orifice plate used is a primary element for flow measurement. It is made of steel plate; the differential pressure is created across this orifice plate. The flow transmitter used is a secondary element of flow measurement, basically it converts pressure signal to electrical signal and retransmits this flow signal to remote location without losing signal. Heavy quantity of moisture contained in coke oven, blast furnace or LD gas or mixed gas is gradually condensed in the gas line resulting in accumulation of water in the impulse lines. When the accumulated water in the impulse line rises to transmitter level, it blocks the line from transmitting actual pressure to the transmitter. Thus transmitter gets erratic pressure and acts accordingly. This may affect any one or both the positive and negative line of the impulse line. This will depend upon the gas line layout and design of the impulse lines. For example if the negative line gets blocked during low flow the transmitter will show high flow because the differential pressure across the transmitter will be high. Such erratic flow measurement may result in improper combustion inside the furnace with chances of over or under temperature, or even chances of explosion. -4- In the existing method, in the event of water accumulation the operator should be informed before draining water from impulse line. The control system is put on manual mode from auto mode after braking automation level-II to level-I. The pressure across the transmitter is equalized with the help of manifold unit. Adequate safety precaution to be taken, since this is a very poisonous gas. Water is drained out from both the impulse lines. The manifold unit is normalized. The operator is informed after job is over and the control system is normalized. Thus there exists a need to develop an improved flow impulse system for overcoming the disadvantages of the existing system. SUMMARY OF THE INVENTION Thus the main object of the present invention is to provide a totally safe drainage system for accumulated water from the impulse line. Another object of the present invention is to reduce the time required to drain out the accumulated water. -5- Yet another object of the invention is to reduce the manpower requirement as only one person can do the job safely. These and other objects of the invention can be achieved by providing a pair of small drift pots and a pair of additional drain valves in both the impulse lines. Thus the present invention provides a flow transmitter impulse line for safe drainage of accumulated water from said impulse line, comprising: a positive and negative impulse line connected to either side of an orifice plate in a gas line; a flow transmitter connected to said impulse line through a manifold unit; and drain valves connected to each of said impulse lines for draining out the water from the impulse lines; wherein a pair of drain valves are provided in each line with a draft pot provided between each pair of drain valves for draining out accumulated water from the impulse lines in auto mode. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The invention can now be explained with reference to the figures of the accompanying drawings, where Figure 1 shows conventional impulse line design of flow measurement. Figure 2 shows the improved design of flow transmitter impulse line of the present invention. -6- DETAILED DESCRIPTION The known arrangement for draining the accumulated water in the impulse lines as a result of condensation of moisture in the gas line 1 is shown in Figure 1. The arrangement shows the positioning of the gas line 1, orifice plate 2, the positive and negative impulse lines, manifold unit 4 for equalizing pressure across a transmitter 5 and two drain valves DV. The drain valves DV can be used for draining out accumulated water in the impulse lines. This can be done only when the control system is in manual mode. . Figure 2 shows the improved design of the flow transmitter impulse line of the present invention. In the present invention, two small drift pots 6 are provided in the impulse lines each between a pair of DV1, DV2 and DV3, DV4. The small drift pots 6 can be of, for example 50 mm diameter and 100 mm height. The draining procedure is described hereunder. -7 Drain valve DV1 of the positive impulse line is closed and drain valve DV2 is opened for allowing water from the positive impulse line to drain out. Valve DV2 is then closed and valve DV1 is opened for about one or two minutes. The whole process is repeated for the positive impulse line till all accumulated water is drained out. Similarly the entire process is repeated for the negative impulse time of the transmitter 5. Drift pots 6 are preferably as small as possible other wise measuring response may effect. In case of any problem valves no DV1 and DV3 may be in closed position in normal time. Before draining, accumulated water in the line can be transferred from line to drift pot 6 by opening valves DV1 and DV3 and keeping valves DV2 and DV4 closed. After transferring water it can be drained out by using above-mentioned procedure. The frequency of water draining may be decided after gaining experience in system in few days. -8- Some of the advantages of the improved flow impulse system of the present invention over conventional system in case of water draining from impulse line are: Here there is no need of braking of auto mode to manual mode and automation Level-II to Level-I control. Prior information to operator is not mandatory. 100% safety during draining water, no need to take extra precaution as required in earlier case. Total process time is low compare to conventional system. Only one person can do these jobs safely. No expertise is required for controlling furnace during this period as require in conventional system.

Full Text

-2-
FIELD OF APPLICATION
The present invention relates to a flow transmitter impulse line for safe drainage of accumulated water from the impulse line.
BACKGROUND OF THE INVENTION
The flow in the impulse system is proportional to square root of differential pressure iewhere Q = flow, k = constant, P1 = pressure
before orifice, P2 = pressure after orifice plate. This differential pressure is tapped and transmitted through a tube and connected to a differentia! pressure transmitter and this tube further extended and connected with a drain valve.
In a flow impulse system the impulse line is a transmission media in which differential pressure is transferred to flow transmitter, this is usually made of high quality steel tube and the diameter varies from 10 to 25 mm. To collect differential pressure across the orifice plate this impulse line is used.
A drain valve is used for purging or draining of impulse line.

-3-
A manifold unit is used for equalizing pressure across the transmitter. This is a safety device for transmitter, used during calibration, removing or fixing of transmitter.
The orifice plate used is a primary element for flow measurement. It is made of steel plate; the differential pressure is created across this orifice plate.
The flow transmitter used is a secondary element of flow measurement, basically it converts pressure signal to electrical signal and retransmits this flow signal to remote location without losing signal.
Heavy quantity of moisture contained in coke oven, blast furnace or LD gas or mixed gas is gradually condensed in the gas line resulting in accumulation of water in the impulse lines.
When the accumulated water in the impulse line rises to transmitter level, it blocks the line from transmitting actual pressure to the transmitter. Thus transmitter gets erratic pressure and acts accordingly. This may affect any one or both the positive and negative line of the impulse line. This will depend upon the gas line layout and design of the impulse lines. For example if the negative line gets blocked during low flow the transmitter will show high flow because the differential pressure across the transmitter will be high. Such erratic flow measurement may result in improper combustion inside the furnace with chances of over or under temperature, or even chances of explosion.

-4-
In the existing method, in the event of water accumulation the operator should be informed before draining water from impulse line. The control system is put on manual mode from auto mode after braking automation level-II to level-I. The pressure across the transmitter is equalized with the help of manifold unit. Adequate safety precaution to be taken, since this is a very poisonous gas. Water is drained out from both the impulse lines. The manifold unit is normalized. The operator is informed after job is over and the control system is normalized.
Thus there exists a need to develop an improved flow impulse system for overcoming the disadvantages of the existing system.
SUMMARY OF THE INVENTION
Thus the main object of the present invention is to provide a totally safe drainage system for accumulated water from the impulse line.
Another object of the present invention is to reduce the time required to drain out the accumulated water.

-5-
Yet another object of the invention is to reduce the manpower requirement as only one person can do the job safely.
These and other objects of the invention can be achieved by providing a pair of small drift pots and a pair of additional drain valves in both the impulse lines.
Thus the present invention provides a flow transmitter impulse line for safe drainage of accumulated water from said impulse line, comprising: a positive and negative impulse line connected to either side of an orifice plate in a gas line; a flow transmitter connected to said impulse line through a manifold unit; and drain valves connected to each of said impulse lines for draining out the water from the impulse lines; wherein a pair of drain valves are provided in each line with a draft pot provided between each pair of drain valves for draining out accumulated water from the impulse lines in auto mode.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be explained with reference to the figures of the accompanying drawings, where
Figure 1 shows conventional impulse line design of flow measurement.
Figure 2 shows the improved design of flow transmitter impulse line of the present invention.

-6-
DETAILED DESCRIPTION
The known arrangement for draining the accumulated water in the impulse lines as a result of condensation of moisture in the gas line 1 is shown in Figure 1. The arrangement shows the positioning of the gas line 1, orifice plate 2, the positive and negative impulse lines, manifold unit 4 for equalizing pressure across a transmitter 5 and two drain valves DV. The drain valves DV can be used for draining out accumulated water in the impulse lines. This can be done only when the control system is in manual mode.
. Figure 2 shows the improved design of the flow transmitter impulse line of the present invention.
In the present invention, two small drift pots 6 are provided in the impulse lines each between a pair of DV1, DV2 and DV3, DV4.
The small drift pots 6 can be of, for example 50 mm diameter and 100 mm height.
The draining procedure is described hereunder.

-7
Drain valve DV1 of the positive impulse line is closed and drain valve DV2 is opened for allowing water from the positive impulse line to drain out. Valve DV2 is then closed and valve DV1 is opened for about one or two minutes. The whole process is repeated for the positive impulse line till all accumulated water is drained out.
Similarly the entire process is repeated for the negative impulse time of the transmitter 5.
Drift pots 6 are preferably as small as possible other wise measuring response may effect. In case of any problem valves no DV1 and DV3 may be in closed position in normal time.
Before draining, accumulated water in the line can be transferred from line to drift pot 6 by opening valves DV1 and DV3 and keeping valves DV2 and DV4 closed. After transferring water it can be drained out by using above-mentioned procedure. The frequency of water draining may be decided after gaining experience in system in few days.

-8-
Some of the advantages of the improved flow impulse system of the present invention over conventional system in case of water draining from impulse line are:
Here there is no need of braking of auto mode to manual mode and automation Level-II to Level-I control.
Prior information to operator is not mandatory.
100% safety during draining water, no need to take extra precaution as required in earlier case.
Total process time is low compare to conventional system. Only one person can do these jobs safely.
No expertise is required for controlling furnace during this period as require in conventional system.

METHOD FOR MEASUREMENT OF FLOW IN GAS LINE USING IMPROVED FLOW TRANSMITTER IMPULSE LINE SYSTEM

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