SU1393901A1 - Apparatus for controlling the feed of inhibitor of hydrate formation into fuel gas pipelines - Google Patents

Description

(21) 4094572 / 24-26

(22) 07/14/86

(46) 05/07/88. Bul Number 17

(71) Special Design Bureau Promavtomatika

(72) V.AShatsyuk, A.V. Likhachev and E.K.Kiyko

(53) 55.012-52 (088.8) (56) USSR Copyright Certificate No. 367872, cl. G 05 D 7/00, 1971. USSR Copyright Certificate No. 551618, cl. G 01 D 11/13, 1975.

(54) A CONTROL DEVICE FOR THE SUPPLY OF AN INHIBITOR OF HYDRATE FORMATION IN NATURAL GAS GAS PIPELINES The device contains connectors with the outputs of the first switches 44 two

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with

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Positional valves 17-20, installed on lines 13-- 6 of supply to points 9-12 of input to the inhibitor gas lines 4 and 5, connected via manifold 8 to pump 7, interconnected sensors 23 J, 26 differential pressure and elements 27, 28 comparisons, the second inputs of which are connected to setters. The inputs of the sensors 23 and 26 are connected by lines 13 15 and 14 ,, 16 with gas pipelines-4 and 5 o. The outputs of the generator 44 are connected to the inputs of the elements 42 interconnected with the second inputs.

This invention relates to devices for controlling the flow of a hydrate inhibitor introduced into a natural gas stream.

The purpose of the invention is to reduce the loss of productivity of gas pipelines by increasing the reliability of hydrate formation control.

FIG. 1 is a schematic diagram of the proposed. The device in FIG. 2 is a diagram of the generator of control pulses j in FIG. 3, a sequence diagram of the operation of the device.

The device contains a system for collecting natural gas from a number of wells, for example, .1 and 2 to an integrated gas treatment unit 3 (GTU) through gas pipelines 4 and 3 corresponding to each well. At the entrance to the GPP 3 in gas pipelines 4 and 5, control valves 6 are installed.

To prevent the formation of hydrates during gas transportation from the wells to the gas treatment unit, the latter is equipped with a centralized supply point for hydrate formation inhibitor 5 such as methanol, ensuring its supply from the pumping unit 7 through the collector 8 to the injection points to the gas pipelines 4 and 5s at the wellhead 1 and 2 respectively points 9 and 10e in front of the control valve 6, points P and 12. The supply of methanol to these points is carried out along individual lines 13-16 of the inhibitor feed, respectively.

In each of these lines there are two-way valves 17–20, respectively.

pulse widths and the first inputs of the second switches 45 of memory elements 46 and 42, 47 elements. The outputs of the latter are connected to the inputs of the first switches 44 through elements No. 43; Each of the two outputs of the comparison elements 27 and 28 is connected to the second inputs 1x second switches 45, the outputs of which are connected to the second inputs of the memory elements 46, interconnected with the second inputs of the second And 47 elements. 3 Il.

Pulse lines 21 and 22 are connected to lines 13 and 15 after valves 17 and 19, communicating with the measuring chamber of pressure differential sensor 23, for example a differential pressure gauge. Pulse lines 24 and 25 connected to measuring chambers of differential pressure sensor 26 are connected to lines 14 and 16 after valves 18 and 20.

The outputs of the sensors 23 and 26 are connected to the first inputs of the comparison elements 27 and 28, respectively. The second input of each reference element is associated with a reference signal adjuster. Wherein

Each comparison element 27 and 28 has two different polarity outputs 29, 30 and 31, 32 corresponding to positive and negative mismatch of the signals at the input of the elements.

The device also contains a multichannel generator 33 control pulses and a series of channels 34-37 for controlling valves 17, 19, 18 and 20, respectively. At the same time, to each of the outputs of the multichannel generator 33, two channels 34, 35 and 36, 37 are simultaneously connected to control valves 17, 19 and 18, 20, respectively, one

gas pipeline.

Each control channel has two inputs — the first 38 and the second 39, as well as the corresponding two branches of the input signals corresponding to these inputs.

to the control channel output 40. The first branch from the input 38 is equipped with series-connected setting device 41 for the duration of control pulses,

element 42 and element OR 43 and switch 44.

The second branch from the second input 39 comprises a second switch 45 connected in series, a controllable memory element 46, a second element AND 47, the output of the latter being connected to the second input of the element OR 43, The second input of the second element And 47, and also the control inputs of the element 46, the memory and the switch 45 are connected to the first input 38 of the control channels associated with the first output of the multichannel generator 33 equal pulses.

The second inputs 39 of control channels 34 and 35 are connected to opposite-polar outputs 29 and 30 of the comparison element 27,

Another pair of control channels 36 and 37 is connected in the same way. The first inputs 38 of these channels are connected to the second output of the generator 33, and the second inputs 39 to the opposite outputs 31 and 32 of the reference element 28, respectively. The inputs of the setters 41 are connected to the outputs of the multichannel temporary device 48.

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When controlling the operation of the valves 17-20 in the continuous injection mode of the inhibitor, the following operations are performed. Originally known theoretical

T-pulse generator 33 -qn

/. „0% / about KIM formulas calculate the consumption (Fig. 2) contains the source 49 of the power supply - - g-, g

AC power, generator

50pr pulses, divider

51 frequencies, low-order counters

52 and high-order 53, decoders 54 and 55, which convert the binary digital code of the counters 52 and 54 into decimal,

The outputs of the decoders 54 and 55 of the generator 33 control pulses are connected to the master inputs (units and

the total consumption of methanol for each of lines 13, 15, and 14, 16 (q, where i is the line number). On the basis of these data, the required duration is calculated, 35 valves are turned on using the formula

one

.

  q; f

where qo

40

ten) setpoint 41 the duration of the control pulses of each control channel through the multichannel temporary device 48.

The device works as follows.

Natural gas from wells 1 and 2 is transported through gas lines 4 and 5 to the GPP 3, where gas is absorbed. The regulation of variable gas consumption with a gas treatment unit is made by changing the flow area of the control valve b installed in each of the gas pipelines 4 and 5 at their entrance to the gas treatment unit. In accordance with the thermodynamic conditions of gas transportation in a number of fields, hydrate formation is possible in gas pipelines.

45

50

55

set reagent consumption through an open valve; f is the frequency of the follow-on signals of the valve per unit of time (adjusted by the pulse generator 33). The f value for all valves can be permanently adjusted for ease of calculations and servicing. The repetition period of the control pulses (T T;) is determined by the geological and operating parameters of the specific CGT of the field and is chosen to be shorter than the possible time of hydration.

A generator 50 rectangular pulses when powered from a source 49 generates electrical pulses, with a given frequency arriving at the input of the divider 51 frequency. At the output of the latter by means of sequential

ten

3901

4 and 5 (wells) and in the sections of control valves 6. Therefore, to prevent hydrate formation in the wells (pipelines 4 and 5), a hydrate formation inhibitor (methanol) is fed to the wellhead at points 9 and 10 through lines 13 and 14, and in order to protect against hydrate formation in control valves 6, to points 11 and 12 along lines 15 and 16. Methanol is supplied to all injection points by pumping it with pump 7 installed on the 15th GTU to collector 8 and further along lines 13-16.,.

To regulate the flow of methanol through lines 13-16, respectively. VII with technological need use the slots two-way controlled shut-off valves 17–20 installed in them, which pass through channels of bulk portions of methanol proportional to the valve opening time.

When controlling the operation of the valves 17-20 in the continuous injection mode of the inhibitor, the following operations are performed. Originally known theoretical

- - g-, g

the total consumption of methanol for each of lines 13, 15 and 14, 16 (q, where i is the line number). Based on these data, calculate the required valve turn-on time using the formula

one

.

  q; f

where qo

0

five

0

five

set reagent consumption through an open valve; f is the frequency of the follow-on signals of the valve per unit of time (adjusted by the pulse generator 33). The f value for all valves can be permanently adjusted for ease of calculations and servicing. The repetition period of the control pulses (T T;) is determined by the geological and operating parameters of the specific CGT of the field and is chosen to be shorter than the possible time of hydration.

A generator 50 rectangular pulses when powered from a source 49 generates electrical pulses, with a given frequency arriving at the input of the divider 51 frequency. At the output of the latter through serial

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lapis formed

on it i vn m l s

15

rectangular impulses frequency 1 Hz. The pulses of this frequency are fed to the input of the counters 52 and 53, the ac of the latter to the decoders FOR and 55, which convert the binary codes of the counters 52 and 53 into a tenth sequence of pulses (the decoder 54 is one, the decoder 55 is ten) "From the decoder Levels 54 and 55 pulses through a multichannel temporary device 48 are fed to the inputs of knobs 41 / cursors, the switches of which manually dial a two-digit number corresponding to the required duration of control pulses Tj (in seconds) for each control channel.

A temporary device .48 provides a predetermined sequence of pulses of decoders 54 and 55 to setters 41, which are connected to the decoders in groups that correspond to pairs of control channels for the inhibitor supply valves to one gas pipeline: the first group — setters 41 of channels 34 and. 35, the second group - controllers 41 channels 36 and 37, etc. The switching time of each channel group is shifted relative to the subsequent one by the value of T / n, n is the number of groups (in Fig. 1, the device consists of two groups). Initially, the pulses are passed to the first group in channels 34 and 35.

When the pulses at the output of the decoders 54 and 55 coincide with the 41 numbers at the output of the AND 42 elements peaJSh; the output is a discrete signal that goes to the first input of the ICH element: 43 and from the last output to the input of the switch 44.

25

thirty

35

40

55

45

In this case, the switches 44 of the tapes 34 and 35 of the shunt control panel connect the control voltage to the control inputs of the two-way shut-off valves 17 and 19, the voltage being applied to the latter at the same time and released after; the time specified for each class 50 Pan 1 and 19 Ead 41 of the corresponding control channel (34 or 35)

55

When signals are received at the shut-off valves 17 and 19, they open, allowing the inhibitor to flow from collector 8 through lines 13 and 15 to points 9 and 11. pipeline 4 for a given time ij,

Simultaneously with the arrival of the signal from the generator 33 of control pulses, the first signal 38 of the control channels 34 and 35 receives the same signal in these channels and to the second input of the second And 47 elements, as well as to the control inputs of the memory elements 46 and the disconnect switches 45. In this case, the contacts of the switch 45 open and disconnect the different-polar outputs 29 and 30 of the comparison element 27 from the second inputs of the control channels 34 and 35.

Thus, when valves 17 and 19 of the first group are turned on for supplying methanol, automatic disconnection from inputs 39 of channels 34 and 35 of different polarity outputs 29 and 30 of comparison element 27 connected with sensor 23 for measuring pressure difference in lines 13 and 15 of methanol supply .

By

And 3

The closure switches are removed, switch 44 shuts off the control voltage to the control inputs of valves 17 and 19, which then lock up, stopping the supply of methanol through lines 13 and 15. However, the signal at the first inputs 38 of channels 34 and 35 from pulse generator 33 is not removed until the end of the cycle of operation of the first group of valves, i.e. during the whole time T / n, therefore during this time the connection of the outputs 29 and 30 of the comparison element 27 with the second inputs 39 of the channels 34 and 35 is broken by the switches 45.

after the set time and t-, discrete signals with input5

0

In this cycle of operation of valves 17 and 19, another group of valves 18 and 20 is closed and the inhibitor is not supplied to lines 5 and 14 in the gas line 5. At this time, the gas line 5 is monitored for the presence of hydrates in it using a differential pressure sensor 26, which pulsed lines 24 and 25 measure the resistance of the pipeline 5 in the area between the injection inhibitor injection points 10 and 12, in the absence of methanol flow in lines 14 and 16. The control inputs of the disconnect switches 45 of the channels 36 5 and 37 are de-energized, the switches of these 45 channels are closed s 31 and 32 comparing element 28 are connected to second inputs 39 and 37 of the channels 36, providing a flow of signals to uprav7

lemmy elements 46 memories of

The output signal of the sensor 26, corresponding to the measured value of the resistance of the pipeline 5 at a fixed position of the shut-off and control valves 6, is fed to the input of the comparison element 28 and is compared in it with a predetermined reference value of the signal.

If the output signal of the sensor 26 is greater than the reference, which indicates an increase in the resistance of the pipeline 5 with an unchanged reference for the gas flow and the possible formation of hydrates in it between points 10 and 12, the comparison element 28 generates a signal that comes from output 31 to the second input 39 of the channel 36, where a closed contact of the disconnect switch 45 passes to the input of the memory element 46. If the output signal of the sensor 26 is less than the specified value, which indicates a decrease in the resistance of the pipeline 5 and the possible formation of hydrates on the shut-off and control valves 6, the comparison element forms a signal from the output 32 to the second input 39 of the channel 37 and through the closed contact switch 45 to the input of the memory element 46 of this channel.

After the time T / n of the operation of the first throat channel 34 and 35, the control signal from the first inputs 38 of these channels is removed by the generator 33, since the temporary device 56 connects the second group of sensors 415 to the decoders to the first inputs 38 of the channels 36 and 37 management The cycle of the second group begins (Fig. 3). In this cycle, the control signal from generator 33 passes in channels 36 and 37 to pulse width adjusting devices 41 and then successively through elements AND 42 and OR 43, closing the contacts of switch 44, passes to the channel output to control inputs of valves 18 and 20,

ten

15

20

25

The valves then open, providing methanol from the manifold through lines 14 and 16 to the pipeline 5.

The control signal from the input 38 of the channels 36 and 37 simultaneously passes to the second switch 45, the controlled elements 46 of the memory and the second elements And 47.

139390 8

These channels. In this case, the switches 45 break the connection of the second inputs 39 with different outputs 31 and 32 of the comparison element 28, and the memory elements 46 transfer the signal recorded in them to the second input of the AND elements 47, freeing the cell for recording the new signal .

If there are two signals at the inputs of the second element AND 47 (a signal from the memory element 46 and input 38), a discrete signal is generated at the output of the element 47, which is fed to the second input of element 1-rm 43. This signal is synthesized over time T / A5 is equal to the signal transit time from input 38 on the second branch of the control channels. The IHI element 43 provides for the passage to the switch 44 of either a signal from its first input from the setpoint generator 41 of the duration through the AND element 42, or from the second input from the memory element 46 through the And 47 element.

In the first case, the contacts of the switch are closed for a time equal to T, and set by setpoint 41, in the second for a time T / n. This corresponds to the fact that when the hydration situation is fixed in the interrogation cycle of the sensor 26 produced in the previous cycle of the first group of valves 17 and 19, the valves 18 or 20, depending on the fixation of the hydrate formation signal in the channels 36 or 37, continue to remain open after the expiration time during the whole. cycle T / n work of the second group. The increased time () of supplying the inhibitor to the corresponding point 10 or 12 of the injection of the inhibitor into the gas pipeline 5 ensures the prompt elimination of the situation of hydrate formation in the gas pipeline.

At the same time in the cycle of the second group in the absence of a control signal at the inputs of 38 channels

34 and 35 of the first group

the switches 45 in these channels are de-energized and their contacts are closed, while the opposite polarity outputs 29 and 30 of the comparison element 27 are connected to the second inputs 39 of these channels, providing signals through the closed contacts from the switches 45 to the inputs of the memory elements 46. . .

Similarly, the pressure differential sensor 23 is polled in order to monitor the presence of hydrates: if the output

thirty

35

40

45

50.

55

ten

15

20

25

thirty

35

40

45

50.

55

the sensor signal 23 is greater than the reference, the comparison element 27 generates a signal that comes from the output 29 n | and the second input 39 of channel 34 and then through the switch 45 to the memory element 46 of this channel, if the output signal of the sensor 23 is less than the reference, the signal from output 30 Comparison element 27 proceeds in a similar manner to memory element 46 of channel 35.

Next, the operation cycles are repeated: to | control channels 34 and 35, the pulse generator signal 33 activates valves 17 and 19, disconnecting the second inputs 39 of these channels from the outputs 29 and 30 of the reference element 27, and in channels 36 and 37 of the control valves Methanol supply 1 and 20 are disconnected, and a differential pressure sensor is polled by connecting channels 36 and 37 of outputs 31 and 32 of comparison element 28 to the second bdes 39.

Cycles of operation of valves at which the supply of inhibitor is made, and | Gas pipeline control cycles, during which the inhibitor is not fed into the gas pipeline being monitored, are not replaced by one another.

Under actual conditions of gas and oil facilities, the number of groups, channels | of the control can be more (up to 4), and the number of pairs of channels in one group nje - up to 8-10, which determines the functionality of the device, regardless of the number of groups and the number of channels. The displacement of the control channel operation cycles by groups is due to the feasibility of reducing the performance and energy of the pumps for the inhibitor supply pumps. By excluding the simultaneous switching on of all valves.

0

five

0

25

thirty

35

40

Claims (1)

Invention Formula about A hydrate formation inhibitor supply control device to natural gas pipelines with control valves installed on them, containing two-way valves connected to the outlets of the first switches, installed on the supply lines of the inhibitor connected through a manifold to the pump, pressure difference sensors connected to the first inputs comparison elements, the second inputs of which are connected to the generator sh, and a generator, characterized in that, in order to reduce the loss of productivity of gas pipelines due to The reliability of hydrate formation control, it additionally contains setting pulses for the duration of the pulses, the first and second elements AND, the elements OR, the memory elements, the second switches and the second lines of the inhibitor supply to the gas pipelines before the regular pressure regulators, while the differential pressure sensors are installed the gas pipeline, the generator outputs are connected to the inputs of the pulse width setting units associated with the second inputs of the first AND elements and the first inputs of the second switches, memory elements and AND gates, the outputs of which through the elements or compounds to the inputs of the first switch, and each of the two output elements comparator is connected to a second input - the respective second switches, the outputs of which are connected to second inputs of the memory elements associated with the second inputs of the second AND gate, Phage.2 34 .47 354L 35 four/ 37 47 Compiled by A. Karetnikov Editor And, Gorna Tehred M. Khodanych Order 1943/29 Circulation 531 VNIIPI USSR State Committee on inventions and discoveries 113035 Moscow, Zh-35, Raushsk nab., 4/5 Fi.Z Proofreader G. Reshetnik Subscription