Method of control of technological parameters at pipeline sections with reduced allowable gas pressures

 

(57) Abstract:

The invention relates to techniques for managing operations of the process gas transportation. The technical result of the invention is the implementation of low-energy process of gas transportation through the current main gas pipeline. This is achieved by regulation of mutual raspredelenie degrees of compression of the compressor stations of gas pipeline from preferential conditions of operation of compressors compressor stations with a minimum compression ratio maximum gas inlet pressure and the maximum gas pressure at the outlet, the choice of modes of compressors compressor stations should be excluded as exceeding the permissible operating pressure of the gas on the pipeline for a compressor station, and going beyond the limits of operational parameters of the compressors, which are defined using combined gas-dynamic characteristics. 3 table.

The invention relates to techniques for managing operations of the process of transportation of gas via trunk gas pipelines through compression, in which Gazoprovod, considered as a system, and is intended for regulation as highlighted sections of trunk gas pipelines, including several compressor stations (CS), and entire trunk gas pipelines from production to gas consumers.

The purpose of the invention is the regulation of the process parameters of gas transportation through the current main gas pipeline, on separate sections between which the COP during operation restrictions permissible operating pressure of the gas relative to the nominal design value for the blowers COP with a minimum total capacity of compression and, therefore, the implementation of the transport gas with minimum energy consumption.

There are recommendations [1; 2] for the implementation process of the transportation of gas via trunk gas pipeline, providing a minimum total capacity of compression compressors by reducing the step between the COP and maintain maximum gas pressures at the outlets of the blowers KS. Recommendations in addition to the indications on the economic feasibility of maintaining the maximum allowable gas pressures at the outlets nineteeth control of process parameters at pipeline differences in maximum permissible voltages on sites and mainly applicable only at the stage of development of the project of construction of the main pipeline using pipe of the same size with the same maximum permissible stresses in the pipe wall.

There is a method of control of technological parameters of the main pipeline [3] (patent SU # 1755000, CL F 17 D 1/00, priority dated November 25, 1987), according to which as regulated quantities taken the degree of pressure increase or the compression ratio of each compressor, the optimum current value which is determined is given in the patent addiction. The main disadvantage of this method lies in the fact that the dependencies do not take into account the physical essence of the process of transport of gas through pipelines by means of compression, i.e. the lack of optimum power compression [1], since, as a rule, the higher the output pressure compressors COP, the less power required compression compressors COP. Besides, this method also does not imply the use of the different values of maximum allowable gas pressures on sections of the pipeline.

In practice, traditionally tend to work with equal capacity compression KS that do not always correspond to the proposed recommendations and the methods of regulation.

Task - develop method of regulating the functioning of the main pipeline, obezlyudela COP minimum, that is, the minimum energy consumption for the transport of gas, in the presence of sections of the pipeline between the COP with reduced relative to the nominal design value of the maximum permissible gas pressure regardless of the size of this reduction and the underlying reasons. Thus regulation of the main pipeline with the same at all sites maximum allowable gas pressures for the proposed method is a special case.

As an object of regulation the main pipeline is a chain of consecutive COP and followed sections of the pipeline, namely:

INPUT 1-I COP the 1st section of the pipeline

2-I KS 2nd section of the pipeline

3-I COP the 3rd section of the pipeline

i-I CS i-th section of the pipeline

(N-1)-I KS (N-1)-th pipeline

N-I CC N-th section of the pipeline OUTPUT.

The implementation of the method is as follows.

1. While the pipeline is measured by conventional methods and means or set the following parameters (i=1; 2; 3;...; N-1; N):

Qi- the charge of the transported gas inlet blowers i-th KS, nm3;

QOPT- desired flow transport is articheski the flow of the transported gas at the outlet of the main gas pipeline, nm3;

POPTthe absolute pressure of the transported gas at the outlet of the main gas pipeline required for submission at the outlet of the main gas pipeline gas flow QOPT(set Manager), MPa;

POthe actual absolute pressure of the transported gas at the outlet of the main gas pipeline, MPa;

PIthe absolute pressure of the transported gas inlet of the main gas pipeline, MPa;

PSTAGE ithe absolute maximum permissible pressure of the gas transported for the section of the pipeline after the i-th KC-defined maximum stresses in the pipe wall or due to other reasons, MPa;

Pl,ithe absolute pressure of the gas transported on the input of the i-th CS, and R1.1=PI, MPa;

P2,ithe absolute pressure of the gas transported on the output of the i-th COP, MPa;

T1,ithe temperature of the transported gas inlet of the i-th KS, K;

T2,ithe temperature of the gas transported after the i-th COP, K.

2. Determine the actual compression ratio compressors i-th KC

i=P2,i/P1,i

and the average temperature gas stations

5. Register control signals to increase or decrease gas pressure at the outlet of the COP issued arranged below in the direction of gas adjacent the COP, and turned off the blower.

6. Control actions performed on each of the i-th CS (i=1; 2; 3;...; N-1), except the last N - allowable compression ratio and maximum permissible pressures at inlet and outlet. If necessary, reducing the pressure of the gas at the outlet of the COP is consistent with its predominant implementation by reducing the degree of compression compressors COP. If necessary, increase the pressure of the gas at the outlet of the COP is consistent with its predominant implementation through simultaneous growth of input and output pressures without changing the mode or degree of compression compressors COP due to growth in output pressure with increasing compression blowers from the previous COP, for which the input pressure is fixed, for example, because it is for the gas pipeline first and has the specified inlet pressure or because the output pressure of the previous COP has the maximum value. Specific management actions must meet the guidelines described in the table.1.

7. The last N-th COP should be aimed at ensuring the gas pressure POequal to POPTwith minimal compression blowers. Specific management actions implemented on the N-th COP, depending on the registered settings with regard to the priorities referred to in paragraph 6 shall meet the recommendations predstavliati compression and the average temperature on p. 2, to compare the data obtained in accordance with PP 3 and 4, register control signals on p. 5 and Refine management actions according to PP 6 and 7.

If the task Manager at the outlet of the main gas pipeline it is necessary to maintain the equality QOand QOPTand not POand POPTabove the control actions are the same.

The proposed method is easy to implement using existing transmission pipelines systems power automation that supports the outlet pressure of the compressor is equal to the specified value. Although in this case, as formally regulated value is used, the outlet pressure of the blower COP, however, the actual controlled variable is the compression ratio of the supercharger, because this value is crucial for the regulation. At the same time from the aggregate system automation can be obtained for the implementation of the proposed method the data for the maximum and minimum degrees of compression blowers, taking into account the limit values for the maximum and minimum volume of their performance, drive power, the permissible throttle frequent the signal is corresponding signal, obtained from the aggregate system automation for any fan of the group.

The signals on the limitation of operational parameters of the compressors can be formed without the use of aggregate systems automation, if generated according to the proposed method the control system will be established individually combined gas-dynamic characteristics of the compressors COP with indication of the boundaries of acceptable operating parameters. The position of the operating points of the blowers on the characteristics of the installed conventional methods directly on measured parameters (costs, compression ratio, speed, temperature).

The analysis of the level of technology has allowed to establish that the applicant is not detected similar, characterized by signs, identical to all the essential features of the claimed invention, therefore, it meets the criterion of “novelty.”

An example implementation of the proposed method of regulation of the main pipeline and its advantages in comparison with the method, recommending the operation of the blowers COP at maximum output pressure gas, as well as traditionally used in the present method, Comair does not exceed the restriction of the output pressure. Comparison with the method for adjustment in the patent SU # 1755000, is impossible, since there are no guidelines for its use when the differences in the maximum allowable pressure on individual sections of the pipeline.

Considered the main gas pipeline from pipe Dy=1400 mm without limit selections containing 5 CC (N=5) sections of pipelines after them. In all areas is transported by the same natural gas consumption QOPT=1040 nm3/s (mass flow rate of 695 kg/s) at an average temperature of 285 K. Polytropic efficiency compressors COP adopted equal to 0.8. To exclude consideration of selection of gas for own needs of the COP, no significant impact on the results obtained, adopted the option of using electrically driven compressors with variable speed. The absolute gas pressure at the entrance to the pipeline PIand required for the transportation of the specified gas flow pressure at the outlet of the pipeline POPTequal to 5.5 MPa. The maximum allowable absolute pressure of gas for gas pipeline sections 1, 3 and 5 is 7.6 MPa, for sections of the pipeline 2 and 4 it is reduced to 7.0 MPa, and in other areas of the pipeline and compressors COP identify the different gas pressures (input COP 5.5 MPa, the output - 6,97 MPa) using the same degrees of compression compressors COP equal to 1.27. The total capacity of compression in this case is 139,4 MW (taken as 100%).

CW operation with a maximum output pressure of the gas increases the total capacity of the compression up to USD 151.6 MW (108,8%). This is because when the maximum permissible pressures at the outlets of the blowers KS-1 and KS-3, equal to 7.6 MPa, the transport gas may be carried out only when the blower KS-2 and KS-4, because when created in these conditions at the inputs of KS-2 and KS-4 the pressure of 6.3 MPa operation of the blowers KS-2 and KS-4 with an output pressure of 7.0 MPa is possible only if the degree of compression below the minimum, equal to 1.2.

Mutual distribution of the degrees of compression of the COP recommended in accordance with the proposed method of regulation of the main pipeline, reduces total power compression to 133,0 MW (95.4 percent).

More detailed numerical data of the example implementation presented below in table.3.

Thus, the proposed method of control of the main gas pipeline allows to ensure the transport of gas minimum total capacity of compressor stations to minimize the energy consumption for the transportation of gas.

Comparison of the essential features of the proposed and known ways of regulating the main pipeline gives reason to believe that the proposed method meets the criteria of “inventive step” and “industrial applicability”.

Literature

1. DOBROKHOTOV C. D. Centrifugal blowers natural gas. M.: Nedra, 1972, pp. 9-14.

2. TEMPEL, F. G., MASLOV A. MT Technology mode gaspereau. Leningrad: Nedra (Leningrad. div.), 1974, pp. 37, 38.

3. MATVEEV centuries the Method of regulation of a gas pipeline (patent SU # 1755000, CL F 17 D 1/00, priority dated November 25, 1987).

Method of control of technological parameters of the existing gas main on separate sites which during operation permissible gas pressure is reduced from the nominal design values, using as the main regulated value of the compression ratio of the supercharger compressor station consisting in measuring the parameters of the transported gas, determining the actual values of controlled variables and parameters of operation of the blowers, comparing them with valid values and the adjustment of the operating compressors compressor stations, characterized in that the primary work of blowers with minimum compression and maximum permissible pressures at inlet and outlet, the choice of modes of operation of the blowers are subject to margins of operational parameters, determined using a combined gas-dynamic characteristics of the blower.

 

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