Natural gas adsorption tower control method, device and system
Technical Field
The invention relates to the technical field of natural gas purification, in particular to a method, a device and a system for controlling a natural gas adsorption tower.
Background
The natural gas is a clean energy and chemical raw material, a natural gas long-distance pipeline in China conveys the natural gas to each natural gas valve station in a high-pressure gas conveying mode, and the natural gas is conveyed into a downstream pipe network after being subjected to pressure reduction treatment or is liquefied into liquefied natural gas for users to use.
Generally, a raw gas from a natural gas station contains impurities such as water, mercury, and acid gas, and each impurity has a serious influence on a system for depressurizing natural gas. For example, the water content in the natural gas and the natural gas form hydrates under certain conditions to block pipelines, which affects the cooling liquefaction process; acid gas in natural gas can form acid in free water, thus eroding pipelines and equipment; the corrosion of aluminum equipment and pipelines by mercury is severe; in addition, unnecessary power consumption is caused due to the existence of moisture; because of the low natural gas liquefaction temperature, the presence of water and acid gases can also lead to freeze-plugging of the equipment and must be removed.
In order to solve the problem, the common mode at present is to purify the raw material gas of each natural gas valve station by a purification system before the natural gas is depressurized. At present, a plurality of purification units are generally arranged in a purification system, each purification unit is internally provided with a plurality of adsorption towers, each adsorption tower is filled with an adsorbent to selectively remove impurities such as acid gas, mercury, water and the like in raw natural gas, and the plurality of towers can simultaneously carry out adsorption and regeneration (desorption) cycle operation. Common adsorption methods are TSA (temperature swing adsorption) and PSA (pressure swing adsorption). The TSA adsorption mode is that natural gas entering from the bottom of a tower adsorbs impurities such as acid gas, water and the like in the gas under the action of an adsorbent in the tower, and after adsorption is finished, high-temperature desorption gas is used for regeneration, namely the adsorbent is used for adsorbing the impurities such as water, acid gas and the like at normal temperature or low temperature, and then the adsorbent is subjected to desorption regeneration at high temperature to form a regeneration cycle of the adsorbent, so that the purposes of continuous separation and gas purification are achieved. The PSA adsorption mode is that natural gas entering from the bottom of the tower adsorbs impurities such as acid gas, water and the like in the gas under the action of an adsorbent in the tower, and after adsorption is finished, low-pressure regeneration gas is used for regeneration, namely the adsorbent is used for adsorbing the impurities such as water, acid gas and the like in the natural gas under higher pressure, and then desorption regeneration is carried out under low pressure, so that adsorption and regeneration circulation of the adsorbent is formed, and the purposes of continuous separation and purification of gas are achieved.
In general, TSA includes three sections, i.e., adsorption, regeneration and cold blowing, and a plurality of valves are arranged on an adsorption tower, and the intake of the adsorption, regeneration and cold blowing processes is realized by switching the valves. PSA includes two workshop sections of absorption and regeneration, is provided with a plurality of valves on the adsorption tower, realizes the admit air of absorption and regeneration process through the switching of each valve. At present, a method combining pressure swing adsorption and temperature swing adsorption is often adopted to remove impurities such as acid gas, water, mercury and the like in natural gas, and the process comprises the following steps: high-pressure raw natural gas firstly enters an adsorption tower of PSA (pressure swing adsorption), and H in the high-pressure raw natural gas is selectively adsorbed by multiple adsorbents in sequence2O、CO2、H2S、C5+The impurities are adsorbed, and the unadsorbed natural gas is sent to TSA from the top of the column. When the front edge of the mass transfer zone (called adsorption front edge) of the adsorbed impurities reaches the reserved section of the bed layer outlet, the feed gas inlet valve and the product gas outlet valve of the adsorption tower are closed, the adsorption is stopped, and the adsorption bed starts to shift to the regeneration process. The natural gas treated by PSA enters an adsorption tower of TSA from the bottom of the tower, and is sequentially selectively adsorbed by a plurality of adsorbents, wherein H2O、CO2、H2S and other impurities are almost completely adsorbed, and the unadsorbed natural gas is used as a productThe product gas flows out from the top of the tower and is sent out from the boundary area after being stabilized by the pressure regulating system. Dividing the refrigerating gas from the cold box into three paths, wherein two paths are used as regenerated gas, and one path enters a PSA adsorption tower to desorb an adsorbent in the PSA through pressure swing; the other path is heated by a heater and then washes the TSA adsorption tower to desorb the adsorbent in the TSA until the whole bed layer is heated to about 280 ℃, and H in the bed layer2O、CO2Until the impurities are completely desorbed, entering a cold blowing section; the other path of refrigerator from the cold box is used as cold blowing gas of a TSA cold blowing section to carry out cold blowing and temperature reduction on the adsorbent in the TSA; and inputting the desorbed and cold-blown gas into a natural gas pipe network. The pressure swing adsorption and temperature swing adsorption comprises a plurality of adsorption towers, which form the adsorption and regeneration cycle of the adsorbent, thereby achieving the purpose of continuously separating and purifying gas.
In general, the adsorption time and regeneration time for the TSA adsorption and PSA adsorption purification processes are controlled by switching the valves to change the process state of the adsorption column, and the adsorption time T must be extended to improve the efficiency of the adsorbent and reduce energy consumption1Shortening the desorption time T2However, simple time adjustments may result in reduced adsorption or incomplete desorption. At present, the adsorption and desorption time is usually determined according to the mechanism analysis and engineering practice of the adsorption and regeneration process, but flexible adjustment of the time cannot be carried out according to the specific situation of different raw material gases, which not only reduces the service life and efficiency of the adsorbent, but also can cause increase of energy consumption.
Disclosure of Invention
In view of this, the invention provides a natural gas adsorption tower control method, and aims to solve the problem that the existing control method cannot flexibly adjust the time of each process. The invention also provides a natural gas adsorption tower control device and a natural gas adsorption tower control system.
In one aspect, the present invention provides a natural gas adsorption tower control method for controlling a first adsorption tower and a second adsorption tower, the method comprising the steps of: a valve control step of sending out a control signal for controlling the opening of valves at the adsorption sections of the first adsorption tower and the second adsorption tower; the method comprises the steps of obtaining the flow rate and the impurity content of natural gas in inlet pipelines of adsorption sections of a first adsorption tower and a second adsorption tower and the impurity content of natural gas in outlet pipelines of the adsorption sections of the second adsorption tower; calculating, namely determining a first preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the first adsorption tower, and determining a second preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the second adsorption tower; and an adsorption step, wherein when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time or the impurity content of natural gas in an outlet pipeline of an adsorption section in the second adsorption tower reaches a first impurity preset value, control signals for controlling the valves of the adsorption section of the first adsorption tower and the second adsorption tower to be closed and the valve of a regeneration section to be opened are sent.
Further, the natural gas adsorption tower control method further comprises the following steps: a first regeneration step, namely acquiring the impurity content of natural gas in an outlet pipeline of a regeneration section of a first adsorption tower in real time, and sending a control signal for controlling a valve of the regeneration section to be closed when the impurity content reaches a second impurity preset value; and a second regeneration step, namely acquiring the impurity content of the natural gas in an outlet pipeline of a regeneration section of the second adsorption tower in real time, and sending out control signals for controlling the valve of the regeneration section to be closed and the valve of the cold blowing section to be opened when the impurity content reaches a third impurity preset value.
Further, the natural gas adsorption tower control method further comprises the following steps: and a cold blowing step, namely acquiring the temperature of the natural gas in the outlet pipeline of the cold blowing section of the second adsorption tower in real time, and sending a control signal for controlling the closing of a valve of the cold blowing section when the temperature reaches a preset temperature.
Further, in the above method for controlling a natural gas adsorption tower, the determining a first preset adsorption time according to the flow rate and the impurity content of the inlet pipe of the first adsorption tower in the calculating step further includes: according to the formulaRespectively determining the adsorption time required by each impurity adsorbed by the first adsorption tower; in the formula, T1Adsorption time required for impurities, Q1Full capacity of the first adsorption column1Is the content of the impurity, S, in the natural gas in the inlet pipeline of the adsorption section of the first adsorption tower1' control of the target content of the impurities, F, for the natural gas at the outlet of the adsorption section of the first adsorption column1The flow rate of the first adsorption tower in an inlet pipeline of an adsorption section; and taking the determined minimum adsorption time as a first preset adsorption time.
Further, in the above method for controlling a natural gas adsorption tower, in the calculating step, determining a second preset adsorption time according to the flow rate and the impurity content of the inlet pipe of the second adsorption tower further includes: according to the formulaSeparately determining the adsorption time required for each impurity adsorbed by the second adsorption tower, wherein T is2The adsorption time required for impurities; q2The full load adsorbent adsorption capacity of the adsorption tower of the second adsorption tower is obtained; s2The content of the impurities in the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower; s2' controlling the content of the index for the natural gas at the outlet of the adsorption section of the second adsorption tower; f2The flow rate of the second adsorption tower in the inlet pipeline of the adsorption section; and taking the determined minimum adsorption time as a second preset adsorption time.
The first adsorption tower and the second adsorption tower can determine whether the adsorption process is finished or not according to the impurity content and the flow of the natural gas to be adsorbed or the impurity content of the adsorbed natural gas, namely, the adsorption time can be adjusted according to the specific condition of the impurities, so that the adsorbed gas can meet the requirement; the invention can better fully adsorb impurities in the raw material natural gas, improve the efficiency and the service life of the adsorbent and save energy consumption.
In another aspect, the present invention further provides a natural gas adsorption tower control device, including: the valve control module is used for sending out a control signal for controlling the valves of the adsorption sections of the first adsorption tower and the second adsorption tower to be opened; the acquisition module is used for acquiring the flow and the impurity content of the natural gas in the inlet pipelines of the adsorption sections of the first adsorption tower and the second adsorption tower and the impurity content of the natural gas in the outlet pipeline of the adsorption section in the second adsorption tower; the calculation module is used for determining a first preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the first adsorption tower and determining a second preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the second adsorption tower; and the adsorption control module is used for sending control signals for controlling the valves of the adsorption working sections of the first adsorption tower and the second adsorption tower to be closed and the valve of the regeneration working section to be opened when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time or the impurity content of natural gas in an outlet pipeline of the adsorption working section in the second adsorption tower reaches a first preset impurity value.
Further, the natural gas adsorption tower control device further comprises: the first regeneration module is used for acquiring the impurity content of natural gas in an outlet pipeline of a regeneration section of the first adsorption tower in real time and sending a control signal for controlling a valve of the regeneration section to be closed when the impurity content reaches a second impurity preset value; and the second regeneration module is used for acquiring the impurity content of the natural gas in the outlet pipeline of the regeneration section of the second adsorption tower in real time and sending a control signal for controlling the valve of the regeneration section to be closed when the impurity content reaches a third impurity preset value. The second regeneration control module is also used for sending out a control signal for controlling the valve of the cold blowing section of the first adsorption tower to be opened; and the cold blowing module is used for acquiring the temperature of the natural gas in the outlet pipeline of the cold blowing section of the second adsorption tower in real time and sending a control signal for controlling the valve of the cold blowing section to be closed when the temperature reaches the preset temperature.
In another aspect, the present invention further provides a natural gas adsorption tower control system, including: the first impurity detection unit is used for detecting the impurity content of natural gas in an inlet pipeline of an adsorption section of the first adsorption tower; the first flowmeter is used for detecting the flow of natural gas in an inlet pipeline of an adsorption section of the first adsorption tower; the second impurity detection unit is used for detecting the impurity content of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower; the second flowmeter is used for detecting the flow of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower; the third impurity detection unit is used for detecting the impurity content of the natural gas in the outlet pipeline of the adsorption section of the second adsorption tower; the controller is connected with the first impurity detection unit and the first flowmeter and is used for receiving the impurity content and the flow of the natural gas in the inlet pipeline of the adsorption working section of the first adsorption tower and determining first preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the first adsorption tower; the controller is also connected with the second impurity detection unit, the second flowmeter and the third impurity detection unit, and is used for receiving the impurity content and the flow of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower and the impurity content of the natural gas in the outlet pipeline, and determining second preset adsorption time according to the flow and the impurity content of the natural gas in the inlet pipeline of the second adsorption tower; the controller is also used for sending control signals for controlling the valves of the adsorption sections of the first adsorption tower and the second adsorption tower to be closed and the valve of the regeneration section to be opened when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time or the impurity content of natural gas in an outlet pipeline of the adsorption section of the second adsorption tower reaches a first preset impurity value.
Further, the above natural gas adsorption tower control system further comprises: the fourth impurity detection unit is used for detecting the impurity content of the natural gas in the outlet pipeline of the regeneration section of the first adsorption tower in real time; the controller is connected with the fourth impurity detection unit and used for receiving the impurity content and sending a control signal for controlling the closing of a valve at the regeneration section of the first adsorption tower when the impurity content reaches a second impurity preset value; and/or the fifth impurity detection unit is used for detecting the impurity content of the natural gas in the outlet pipeline of the regeneration section of the second adsorption tower in real time; the controller is connected with the fifth impurity detection unit and used for receiving the impurity content and sending out a control signal for controlling the valve of the regeneration section of the second adsorption tower to be closed when the impurity content reaches a third impurity preset value.
Further, in the natural gas adsorption tower control system, the controller is further configured to send a control signal for controlling the valve of the cold blowing section of the second adsorption tower to be opened; the control system further comprises: the temperature detection unit is used for detecting the temperature of the natural gas in the outlet pipeline of the cold blowing section of the second adsorption tower in real time; the controller is connected with the temperature detection unit and used for receiving the temperature and sending out a control signal for controlling the closing of the valve of the cold blowing section when the temperature reaches the preset temperature.
The control system and the control device of the natural gas adsorption tower have the same principle as the control method, so the control system and the control device have the corresponding technical effects.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a flow chart of a method for controlling a natural gas adsorption tower according to an embodiment of the present invention;
FIG. 2 is a further flow chart of a method for controlling a natural gas adsorption tower according to an embodiment of the present invention;
FIG. 3 is a further flow chart of a method of controlling a natural gas adsorption tower according to an embodiment of the present invention;
fig. 4 is a block diagram illustrating a configuration of a natural gas adsorption tower control device according to an embodiment of the present invention;
fig. 5 is a block diagram of another structure of a control device of a natural gas adsorption tower according to an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a natural gas adsorption tower control system provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of another configuration of a natural gas adsorption tower control system provided by an embodiment of the present invention;
FIG. 8 is a schematic diagram of another configuration of a natural gas adsorption tower control system provided by an embodiment of the present invention;
fig. 9 is a schematic structural diagram of a natural gas adsorption tower control system according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
The embodiment of the control method comprises the following steps:
the control method in this embodiment is applicable to an adsorption mode combining PSA and TSA, where the first adsorption tower a in this embodiment adopts a PSA adsorption mode, the second adsorption tower B adopts a TSA adsorption mode, and the natural gas adsorbed by the first adsorption tower a enters the second adsorption tower B to be continuously adsorbed.
Referring to fig. 6, it will be understood by those skilled in the art that the first adsorption tower a should include an adsorption section and a desorption section, and the first adsorption tower a is generally provided with an adsorption section inlet pipe a1, an adsorption section outlet pipe a2, a regeneration section inlet pipe A3 and a regeneration stage outlet pipe a 4. The raw material natural gas at the adsorption section enters a first adsorption tower through an inlet pipeline A1 of the adsorption section, and flows out of the adsorption tower through an outlet pipeline A2 of the adsorption section after being adsorbed in the first adsorption tower; the regeneration gas enters the first adsorption tower through a regeneration section inlet pipeline A3, and the adsorbent is desorbed and then flows out of the first adsorption tower through a regeneration section outlet pipeline A4. In order to control the gas entering each section, the adsorption section inlet pipeline A1, the adsorption section outlet pipeline A2, the regeneration section inlet pipeline A3 and the regeneration section outlet pipeline A4 are respectively provided with a first valve A11, a second valve A12, a third valve A21 and a fourth valve A22.
The second adsorption tower B should include an adsorption section, a regeneration section and a cold blowing section, and the second adsorption tower B is generally provided with an adsorption section inlet pipeline B1, an adsorption section outlet pipeline B2, a regeneration section inlet pipeline B3, a regeneration section outlet pipeline B4, a cold blowing section inlet pipeline B5 and a cold blowing section outlet pipeline B6. Gas output from an outlet pipeline A2 of an adsorption section of the first adsorption tower A enters a second adsorption tower through an inlet pipeline B1 of an adsorption section of the second adsorption tower B, and flows out of the adsorption tower through an outlet pipeline B2 of the adsorption section after being adsorbed in the second adsorption tower; the regeneration gas enters the second adsorption tower through a regeneration section inlet pipeline B3, and flows out of the adsorption tower through a regeneration section outlet pipeline B4 after desorbing the adsorbent; and cold blowing air flows into the second adsorption tower through a cold blowing section inlet pipeline B5, and flows out of the second adsorption tower through a cold blowing section outlet pipeline B6 after the adsorbent is cooled. In order to control the gas entering each section, the adsorption section inlet pipeline B1, the adsorption section outlet pipeline B2, the regeneration section inlet pipeline B3, the regeneration stage outlet pipeline B4, the cold blowing stage inlet pipeline B5 and the cold blowing stage outlet pipeline B6 are respectively provided with a fifth valve B11, a sixth valve B12, a seventh valve B21, an eighth valve B22, a ninth valve B31 and a tenth valve B32.
Referring to fig. 1, fig. 1 is a flow chart of a method for controlling a natural gas adsorption tower according to an embodiment of the present invention. As shown, the method comprises the following steps:
and step S1, sending out a control signal for controlling the valves of the adsorption sections of the first adsorption tower A and the second adsorption tower B to be opened.
Specifically, a control signal for opening a first valve a11, a second valve a12, a fifth valve B11 and a sixth valve B12 is sent out, so that the raw material natural gas enters the first adsorption tower through an adsorption section inlet pipeline a1 of the first adsorption tower a, is adsorbed in the first adsorption tower, and then enters the second adsorption tower B for continuous adsorption.
And step S2, obtaining the flow rate and the impurity content of the natural gas in the inlet pipelines of the adsorption sections of the first adsorption tower A and the second adsorption tower B, and obtaining the impurity content of the natural gas in the outlet pipelines of the adsorption sections of the second adsorption tower.
Specifically, the flow rate and the impurity content of the natural gas in the adsorption section inlet pipeline a1 may be detected by a flow meter and an impurity-respective detection unit provided on the adsorption section inlet pipeline a1 of the first adsorption tower a, the impurity content and the flow rate of the natural gas entering the second adsorption tower B are detected by an impurity detection unit and a flow meter provided on the adsorption section inlet pipeline B1 of the second adsorption tower B, and the impurity content of the output gas is detected by an impurity detection unit provided on the adsorption section outlet pipeline B2 of the second adsorption tower B.
It should be noted that, in this embodiment, the impurities in the natural gas may include H2O、CO2、C5+Acid gas (e.g. H)2S, etc.), mercury, etc., and may be other impurities known to those skilled in the art, and the specific content of the impurities is not limited in this embodiment.
And step S3, determining a first preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the first adsorption tower A, and determining a second preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower B. The first adsorption time and the second adsorption time in this embodiment may be the same or different, and specific values may be determined according to actual conditions, when the impurity content is high and/or the flow rate is large, the first adsorption time and the second adsorption time are prolonged, and when the impurity content is low and/or the flow rate is small, the first adsorption time and the second adsorption time are shortened.
And step S4, when the actual adsorption time of the first adsorption tower A reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower B reaches a second preset adsorption time, or the impurity content of natural gas in an outlet pipeline of an adsorption section in the second adsorption tower B reaches a first impurity preset value, sending out control signals for controlling the valves of the adsorption section of the first adsorption tower and the second adsorption tower to be closed and the valve of a regeneration section to be opened. The first preset impurity value may be set according to actual conditions, and this embodiment does not limit the first preset impurity value.
Since the adsorption processes of the first adsorption tower and the second adsorption tower in this embodiment are matched, when the first preset adsorption time or the second preset adsorption time is reached, the first adsorption tower and the second adsorption tower are controlled to simultaneously end the adsorption process; in addition, in the present embodiment, the gas after adsorption output from the second adsorption tower is considered, and when the impurity content of the gas meets the preset requirement, the adsorption process is also ended, that is, when any one of the above three conditions is met, the present embodiment controls the end of the adsorption process, that is, closes the first valve a11, the second valve a12, the fifth valve B11 and the sixth valve B12, and opens the third valve a21, the fourth valve a22, the seventh valve B21 and the eighth valve B22, so that the first adsorption tower a and the second adsorption tower B enter the regeneration process.
Compared with the prior art, the first adsorption tower and the second adsorption tower in the embodiment can determine whether the adsorption process is finished or not according to the impurity content and the flow of the natural gas to be adsorbed or the impurity content of the adsorbed natural gas, that is, the adsorption time can be flexibly adjusted according to the specific conditions of impurities, so that the adsorbed gas can better meet the requirements; this embodiment can carry out abundant absorption to the impurity in the raw materials natural gas better, improves the efficiency and the life of adsorbent, practices thrift the energy consumption.
Referring to fig. 2, fig. 2 is a flowchart of a method for controlling a natural gas adsorption tower according to an embodiment of the present invention. As shown, the method comprises the following steps:
and step S1, sending out a control signal for controlling the valves of the adsorption sections of the first adsorption tower and the second adsorption tower to be opened.
And step S2, obtaining the flow rate and the impurity content of the natural gas in the inlet pipelines of the adsorption sections of the first adsorption tower and the second adsorption tower, and the impurity content of the natural gas in the outlet pipeline of the adsorption section in the second adsorption tower.
And step S3, determining a first preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the first adsorption tower, and determining a second preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the second adsorption tower.
And step S4, when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time or the impurity content of natural gas in an outlet pipeline of an adsorption section in the second adsorption tower reaches a first impurity preset value, sending out control signals for controlling the valves of the adsorption section of the first adsorption tower and the second adsorption tower to be closed and the valve of a regeneration section to be opened. The specific implementation process of steps S1 to S4 may refer to the above description, and this embodiment is not described herein again.
And step S5, acquiring the impurity content of the natural gas in the outlet pipeline of the regeneration section of the first adsorption tower in real time, and sending a control signal for controlling the valve of the regeneration section to be closed when the impurity content reaches a second impurity preset value.
Specifically, the content of impurities in the outlet pipeline of the regeneration section can be continuously reduced along with the progress of the regeneration process through the content of natural gas impurities in the outlet pipeline A2 of the regeneration section of the first adsorption tower, and when the content of impurities is equal to the second preset value of impurities, a control signal for controlling the valves of the regeneration section to be closed is sent, namely, the third valve A21 and the fourth valve A22 are closed.
And step S6, acquiring the impurity content of the natural gas in the outlet pipeline of the regeneration section of the second adsorption tower in real time, and sending out control signals for controlling the valve of the regeneration section to be closed and the valve of the cold blowing section to be opened when the impurity content reaches a third impurity preset value.
Specifically, the content of impurities in the outlet pipeline B2 of the regeneration section can be continuously reduced along with the progress of the regeneration process through the content of impurities in the natural gas arranged in the outlet pipeline B2 of the regeneration section of the second adsorption tower, and when the content of impurities is equal to the preset value of the impurities, a control signal for controlling the valve B2 of the regeneration section to be closed, namely a control signal for closing the seventh valve B21 and the eighth valve B22, and opening the ninth valve B31 and the tenth valve B32 is sent.
It should be noted that, in this embodiment, the sequence of step S5 and step S6 is not sequential, and in specific implementation, the first preset impurity value, the second preset impurity value, and the third preset impurity value may be determined according to actual situations, which is not limited in this embodiment.
According to the embodiment, whether the regeneration process is finished or not is determined by monitoring the impurity content of the natural gas in the outlet pipelines of the regeneration sections of the first adsorption tower and the second adsorption tower in real time, so that the adsorbent can be more fully desorbed.
Referring to fig. 3, in the above embodiment, after the step S6, a step S7 may be further included, where the temperature of the natural gas in the outlet pipeline of the cold blowing section of the second adsorption tower is obtained in real time, and a control signal for controlling the valve of the cold blowing section to be closed is sent when the temperature reaches a preset temperature.
Specifically, the temperature in the outlet pipe a6 of the cold blowing section of the second adsorption tower B may be detected by a temperature detecting instrument, and as the cold blowing section proceeds, the temperature in the outlet pipe B6 of the cold blowing section may decrease, and when the temperature decreases to a preset temperature, that is, equal to the preset temperature, a signal for controlling the closing of the first valve B31 and the tenth valve B32 is issued. It should be noted that the preset temperature may be determined according to actual situations, and the present embodiment does not limit the preset temperature.
In this embodiment, the end of the cold blowing section is determined by monitoring the temperature of the natural gas in the outlet pipeline a6 of the cold blowing section in real time, and the real-time monitoring mode can make the adsorbent more sufficiently lower to the preset temperature and better recover the adsorption function of the adsorbent.
In specific implementation, the first preset adsorption time may be determined according to the following method: firstly according to the formulaCalculating adsorption time required for each impurity adsorbed by the first adsorption tower, wherein T is1The adsorption time required for a certain impurity is h; q1The full-load adsorbent adsorption capacity of the adsorption tower of the first adsorption tower is determined by the structure of the device and the property and the mass of the adsorbent, and is a fixed value in kg; s1The content of the impurity in the natural gas of the inlet pipeline of the adsorption section of the first adsorption tower is mg/Nm3;S1' controlling the index content of the impurity in mg/Nm for the natural gas of the pipeline at the outlet of the adsorption section of the first adsorption tower3;F1The flow rate of the inlet pipeline of the adsorption section of the first adsorption tower is shown in Nm3H; and taking the determined minimum adsorption time as a first preset adsorption time. In specific practice, S1' is the index content of the impurity of the natural gas in the outlet pipeline a2 of the adsorption section, that is, the content of the impurity allowed in the natural gas output from the adsorption section, and the content can be determined according to the actual situation, and this embodiment does not limit it at all.
For example, if the first adsorption column can adsorb the impurity H2O、CO2、C5+And H2S, then, firstly, according to the above-mentioned formula, calculating H2O、CO2、C5+And H2The adsorption times required for S are respectively T1、T2、T3And T4Then calculating the minimum of the four adsorption timesAs a first preset adsorption time.
Correspondingly, the second preset adsorption time may be determined as follows: firstly according to the formulaCalculating adsorption time required for each impurity adsorbed by the second adsorption tower, wherein T is2The adsorption time required for a certain impurity is h; q2The full-load adsorbent adsorption capacity of the second adsorption tower is determined by the structure of the device and the property and the mass of the adsorbent, and is a fixed value in kg; s2The content of the impurities in the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower is mg/Nm3;S2' controlling the index content of the impurity in mg/Nm for the natural gas at the outlet pipeline of the adsorption section of the second adsorption tower3;F2The flow rate of the inlet pipeline of the adsorption section of the second adsorption tower is in Nm3And h, taking the minimum adsorption time determined above as a second preset adsorption time. In specific practice, S1' is an index content of impurities in the natural gas in the outlet pipeline a2 of the adsorption section, that is, the content of the impurities allowed in the natural gas output from the adsorption section, and the content can be determined according to actual conditions, and the content is not limited in any way in this embodiment.
To sum up, this embodiment is for guaranteeing the adsorption effect of impurity, need suitably adjust parameters such as adsorption time when the impurity content of raw materials natural gas and flow change, confirms adsorption time according to raw materials natural gas impurity content and flow, reaches better adsorption effect.
Control device embodiment:
referring to fig. 4, fig. 4 is a block diagram of a natural gas adsorption tower control device according to an embodiment of the present invention. As shown, the apparatus comprises: a valve control module 100, an acquisition module 200, a calculation module 300, and an adsorption control module 400. Wherein,
the valve control module 100 is used for sending out a control signal for controlling the valves of the adsorption sections of the first adsorption tower A and the second adsorption tower B to be opened. The obtaining module 200 is used for obtaining the flow rate and the impurity content of the natural gas in the inlet pipelines of the adsorption sections of the first adsorption tower a and the second adsorption tower B, and the impurity content of the natural gas in the outlet pipeline B2 of the adsorption section in the second adsorption tower. The calculation module 300 is configured to determine a first preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the first adsorption tower, and determine a second preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower.
The adsorption control module 400 is configured to send out control signals for controlling the valves of the adsorption sections of the first adsorption tower and the second adsorption tower to be closed and the valves of the regeneration section to be opened when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time, or the impurity content of the natural gas in the outlet pipeline B2 of the adsorption section in the second adsorption tower reaches a first preset impurity value.
The specific implementation process of this embodiment may refer to the above control method embodiment, and this embodiment is not described herein again.
Compared with the prior art, the first adsorption tower and the second adsorption tower in the embodiment can determine whether the adsorption process is finished or not according to the impurity content and the flow of the natural gas to be adsorbed or the impurity content of the adsorbed natural gas, that is, the adsorption time can be adjusted according to the specific condition of the impurities, so that the adsorbed gas can better meet the requirement; this embodiment can carry out abundant absorption to the impurity in the raw materials natural gas better, improves the efficiency and the life of adsorbent, practices thrift the energy consumption.
Referring to fig. 5, the above embodiment further includes: a first regeneration module 500 and a second regeneration module 600.
The first regeneration module 500 is configured to obtain the impurity content of the natural gas in the regeneration section outlet pipeline a4 of the first adsorption tower in real time, and send a control signal for controlling the valve of the regeneration section to be closed when the impurity content reaches a second impurity preset value. The second regeneration module 600 is configured to obtain the impurity content of the natural gas in the regeneration section outlet pipeline B4 of the second adsorption tower in real time, and send a control signal for controlling the valve of the regeneration section to be closed when the impurity content reaches a third impurity preset value. For specific implementation processes of the first regeneration module 500 and the second regeneration module 600, reference may be made to the above-mentioned control method embodiment, and details of this embodiment are not repeated herein.
According to the embodiment, whether the regeneration process is finished or not is determined by monitoring the impurity content of the natural gas in the outlet pipelines of the regeneration sections of the first adsorption tower and the second adsorption tower in real time, so that the adsorbent can be fully desorbed.
In this embodiment, the calculating module 300 can be based on a formulaDetermining a first predetermined adsorption time according to the formulaThe second preset adsorption time is determined, and the specific determination process may refer to the above method embodiment, which is not described herein again.
In the above embodiment, the second regeneration control module 600 is further configured to send out a control signal for controlling the valve of the cold blowing section of the first adsorption tower to open; the embodiment can further comprise a cold blowing module, which is used for acquiring the temperature of the natural gas in the outlet pipeline of the cold blowing section of the second adsorption tower in real time and sending a control signal for controlling the valve of the cold blowing section to be closed when the temperature reaches the preset temperature. The specific implementation process of the cold blowing module may be implemented by referring to the above method embodiment, which is not described herein again.
In summary, the first adsorption tower and the second adsorption tower in this embodiment may determine whether the adsorption process is finished according to the impurity content and the flow rate of the natural gas to be adsorbed, or the impurity content of the natural gas after adsorption, that is, the adsorption time may be adjusted according to the specific situation of the impurities, so that the gas after adsorption can better meet the requirement; this embodiment can carry out abundant absorption to the impurity in the raw materials natural gas better, improves the efficiency and the life of adsorbent, practices thrift the energy consumption.
The control system comprises:
referring to fig. 6 and 7, a preferred structure of the natural gas adsorption tower control system provided in the present embodiment is shown. As shown, the system includes: a first impurity detection unit a5, a first flow meter a6, a second impurity detection unit B7, a third impurity detection unit B9, a second flow meter B8, and a controller 4.
The first impurity detection unit A5 and the first flow meter A6 are both installed on an inlet pipeline A1 of an adsorption section of the first adsorption tower, the first impurity detection unit A5 is used for detecting the impurity content of natural gas in the inlet pipeline A1 of the adsorption section of the first adsorption tower, and the first flow meter A6 is used for detecting the flow rate of the natural gas in the inlet pipeline of the adsorption section.
The second impurity detection unit B7 and the second flow meter B8 are both installed on an inlet pipeline B1 of the adsorption section of the second adsorption tower, the second impurity detection unit B7 is used for detecting the impurity content of natural gas in the inlet pipeline B1 of the adsorption section of the second adsorption tower, and the second flow meter B8 is used for detecting the flow rate in an outlet pipeline B2 of the adsorption section of the second adsorption tower. And the third impurity detection unit B9 is arranged on the outlet pipeline B2 of the adsorption section of the second adsorption tower and is used for detecting the impurity content of the natural gas in the outlet pipeline of the adsorption section.
The controller 4 is connected with the first impurity detection unit a5 and the first flow meter a6, and is used for receiving the impurity content and the flow rate of the natural gas in the inlet pipeline of the adsorption section of the first adsorption tower, and determining a first preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the first adsorption tower.
The controller 4 is further connected with a second impurity detection unit B7, a second flow meter B8 and a third impurity detection unit B9, and is configured to receive the impurity content and the flow rate of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower and the impurity content of the natural gas in the outlet pipeline, and determine a second preset adsorption time according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the second adsorption tower.
The controller 4 is further configured to send out control signals for controlling the valves of the adsorption sections of the first adsorption tower and the second adsorption tower to be closed and the valve of the regeneration section to be opened when the actual adsorption time of the first adsorption tower reaches a first preset adsorption time, the actual adsorption time of the second adsorption tower reaches a second preset adsorption time, or the impurity content of natural gas in an outlet pipeline of the adsorption section of the second adsorption tower reaches a first preset impurity value.
Specifically, the controller 4 may issue control signals that control the opening of the first valve a11, the second valve a12, the fifth valve B11, and the sixth valve 32. After the first valve a11 and the second valve a12 are opened, the raw natural gas enters the first adsorption tower through an adsorption section inlet pipeline a1 of the first adsorption tower, and the flow rate and the impurity content of the natural gas in the adsorption section inlet pipeline a1 are collected through a first flow meter B6 and a first impurity detection unit B5. The controller 4 can be a single chip microcomputer, a DSP and other processors.
In this embodiment, a first preset adsorption time may be determined according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the first adsorption tower, a second preset adsorption time may be determined according to the flow rate and the impurity content of the natural gas in the inlet pipeline of the adsorption section of the second adsorption tower, when the impurity content is high and/or the flow rate is large, the adsorption time is prolonged, when the impurity content is low and/or the flow rate is small, the adsorption time is shortened, and in specific implementation, the first preset adsorption time may be determined according to the following formula:according to the formulaThe second preset adsorption time is determined, and the specific determination process may refer to the above method embodiment, which is not described herein again.
Since the adsorption processes of the first adsorption tower and the second adsorption tower are performed simultaneously in this embodiment, when the first adsorption time or the second adsorption time is reached, the first adsorption tower and the second adsorption tower are controlled to end the adsorption section simultaneously; in addition, in this embodiment, the gas after adsorption output from the second adsorption tower is considered, and when the impurity content of the gas meets the preset requirement, the adsorption section is also ended, that is, when any one of the above three conditions is met, the controller controls the end of the adsorption process, that is, the first valve a11, the second valve a12, the fifth valve B11 and the sixth valve B12 are closed, and the third valve a21, the fourth valve a22, the seventh valve B21 and the eighth valve B22 are opened, so that the first adsorption tower a and the second adsorption tower B enter the regeneration process.
Compared with the prior art, the first adsorption tower and the second adsorption tower in the embodiment can determine whether the adsorption process is finished or not according to the impurity content and the flow of the natural gas to be adsorbed or the impurity content of the adsorbed natural gas, that is, the adsorption time can be adjusted according to the specific condition of the impurities, so that the adsorbed gas can better meet the requirement; this embodiment can carry out abundant absorption to the impurity in the raw materials natural gas better, improves the efficiency and the life of adsorbent, practices thrift the energy consumption.
With continued reference to fig. 6 and 7, the above embodiment may further include: the fourth impurity detection unit A7 is installed on the regeneration section outlet pipeline A4 of the first adsorption tower and is used for detecting the impurity content of natural gas in the regeneration section outlet pipeline in real time; the controller 4 is connected with the fourth impurity detection unit a7, and is used for receiving the impurity content and sending out a control signal for controlling the valve of the regeneration section of the first adsorption tower to close when the impurity content reaches the second impurity preset value.
In the embodiment, the impurity content of the natural gas is detected by the fourth impurity detection unit a7 arranged in the regeneration section outlet pipeline a4 of the first adsorption tower, the impurity content in the regeneration section outlet pipeline is continuously reduced along with the progress of the regeneration process, and when the impurity content is equal to the preset impurity value, a control signal for controlling the valve of the regeneration section to be closed is sent, namely, the third valve a21 and the fourth valve a22 are closed, and the regeneration process of the first adsorption tower is finished. This embodiment can make the adsorbent sufficiently desorbed more sufficiently by monitoring the impurity content of the natural gas in the regeneration section outlet line a2 of the first adsorption tower in real time to determine whether the regeneration process is completed.
With continued reference to fig. 6 and 7, in the above embodiments, a fifth impurity detection unit B10 may be further included. The fifth impurity detection unit is installed on the regeneration section outlet pipeline B4 of the second adsorption tower B and is used for detecting the impurity content of the natural gas in the regeneration section outlet pipeline of the second adsorption tower in real time. And the controller 4 is connected with the fifth impurity detection unit and is used for receiving the impurity content and sending a control signal for controlling the valve at the regeneration section of the second adsorption tower to be closed when the impurity content reaches a third impurity preset value.
In this embodiment, the fifth impurity detection unit B10 is used to detect the impurity content of the natural gas, and as the regeneration process of the second adsorption tower proceeds, the impurity content in the outlet pipeline of the regeneration section of the second adsorption tower will be continuously reduced, and when the impurity content is equal to the third preset impurity value, control signals for controlling the valve closing of the regeneration section and the valve opening of the cold blowing section of the second adsorption tower are sent out, that is, the seventh valve B21 and the eighth valve B22 are closed, the ninth valve B31 and the tenth valve B32 are opened, the regeneration process of the second adsorption tower is ended, and the cold blowing process is started. The embodiment determines whether the regeneration process is finished or not by monitoring the impurity content of the natural gas in the outlet pipeline B4 of the regeneration section of the second adsorption tower in real time, so that the adsorbent can be fully desorbed
Referring to fig. 6 and 7, in the foregoing embodiments, the method may further include: and the temperature detection unit B11 is used for detecting the temperature of the natural gas in the outlet pipeline B6 of the cold blowing section of the second adsorption tower in real time, and the controller 4 is electrically connected with the temperature detection unit B11, receives the temperature and sends out a control signal for controlling the closing of a valve of the cold blowing section when the temperature reaches a preset temperature.
Specifically, after the regeneration section of the second adsorption tower B is finished, the controller 4 controls the valve of the cold blowing section to be opened, and controls the ninth valve B31 and the tenth valve B32 to be opened, and then the cold blowing process is performed. The temperature detection unit B11, which may be a temperature detection instrument, is installed on the outlet pipe B6 of the cold blowing section, and is configured to detect the temperature in the outlet pipe B6 of the cold blowing section, and as the cold blowing section proceeds, the temperature in the outlet pipe B6 of the cold blowing section decreases, and when the temperature decreases to a preset temperature, that is, equal to the preset temperature, a signal for controlling the ninth valve B31 and the tenth valve B32 to be closed is sent out, so as to end the cold blowing section.
In this embodiment, the end of the cold blowing section is determined by monitoring the temperature of the natural gas in the outlet pipeline B6 of the cold blowing section in real time, and the real-time monitoring mode can make the adsorbent more sufficiently lower to the preset temperature, and better recover the adsorption function of the adsorbent.
The operation of this embodiment will be described in detail with reference to fig. 6 and 7:
1) and opening a first valve A11, a second valve A12, a fifth valve B11 and a sixth valve B12, enabling the raw material high-pressure natural gas from the gate station to enter an adsorption section of the purification unit A through an adsorption section inlet pipeline A1 of the first adsorption tower, enabling the gas adsorbed by the first adsorption tower A to enter a second adsorption tower B for continuous adsorption, and enabling the purified high-pressure natural gas output by the second adsorption tower B to enter a cold box to exchange heat with the expanded low-temperature natural gas. When the adsorption starts, the first preset adsorption time T is calculated by detecting the impurity content and the flow of the raw material natural gas inlet1Meanwhile, calculating a second preset adsorption time T according to the detected impurity content and flow in the inlet pipeline of the adsorption section of the second adsorption tower B2The impurity concentration at the outlet of the adsorption section of the first adsorption tower A and the impurity concentration at the outlet of the adsorption section of the second adsorption tower B gradually increase along with the passage of time, when the first preset adsorption time or the second preset adsorption time is reached or the impurity content in the outlet pipeline of the adsorption section of the second adsorption tower reaches the first preset impurity value, the controller 4 controls the first valve A11, the second valve A12, the fifth valve B11 and the sixth valve B12, and simultaneously opens the third valve A21, the fourth valve A22, the seventh valve B21 and the eighth valveAnd B22, finishing the adsorption section and starting the regeneration section.
2) The regeneration gas is respectively input into the regeneration sections of the first adsorption tower and the second adsorption tower through a regeneration section inlet pipeline A3 of the first adsorption tower and a regeneration section outlet pipeline B3 of the second adsorption tower, impurities adsorbed in the adsorbent are desorbed, when the desorption process starts, the outlet impurity concentrations of the first adsorption tower and the second adsorption tower are high, the impurity concentrations gradually decrease along with the passage of time, and when the detected impurity content in the first adsorption tower regeneration section outlet pipeline A4 is lower than the preset impurity value (for example, 1ppm), the controller 4 controls to close the third valve A21 and the fourth valve A22. The desorption process of the second adsorption column is the same as that of the first adsorption column except that after the seventh valve B21 and the eighth valve B22 are closed, the ninth valve B31 and the tenth valve B32 are opened, and the cold blowing process is performed. For the first adsorption tower (PSA adsorption mode), the regeneration gas can be low-pressure natural gas from a liquefaction section as the regeneration gas, impurities in the adsorbent are desorbed through the change of pressure, and the desorbed regeneration gas is output through an outlet pipeline A4 of the desorption section and is sent to a natural gas pipe network; for the second adsorption tower (TSA adsorption mode), the regeneration gas may be low-pressure natural gas from a liquefaction section, the natural gas is heated to 280 ℃ by a heater B12, and then enters a regeneration section as high-temperature regeneration gas to desorb impurities in the adsorbent, and the desorbed regeneration gas is output through an outlet pipeline B4 of the desorption section and sent to a natural gas pipe network.
3) And the low-pressure natural gas enters the second adsorption tower through a cold blowing section inlet pipeline B5 of the second adsorption tower to cool the adsorbent, after the outlet temperature of the cold blowing section reaches the preset temperature, the cold blowing is finished, the next cycle is started, and the low-pressure natural gas used as cold blowing gas is output through a cold blowing section outlet pipeline B6 and enters a natural gas pipe network.
Each valve in the embodiment can be an electric control valve or a hydraulic valve.
Preferably, in specific implementation, the first preset impurity value may be less than or equal to 50ppm, the second preset impurity value and the third preset impurity value may be less than or equal to 1ppm, and the preset temperature may be less than or equal to 40 ℃.
It should be noted that, in specific implementation, referring to fig. 8 and 9, an optimization calculator may be further added, the optimization calculator receives the parameters detected by the first impurity detection unit 1, the second impurity detection unit 3, the flow meter 2 and the temperature detection unit 5, calculates the preset adsorption time, or compares the preset adsorption time with a corresponding preset value, sends a signal for controlling the opening or closing of each valve to the controller 4, and the controller 4 operates each valve according to the received signal. The optimization calculator in the embodiment can be a single chip microcomputer, a DSP and the like.
It should be noted that the principles of the control method, the control device and the control system of the natural gas adsorption tower in the present invention are similar, and the related points can be referred to each other.
In summary, the first adsorption tower and the second adsorption tower in this embodiment may determine whether the adsorption process is finished according to the impurity content and the flow rate of the natural gas to be adsorbed, or the impurity content of the natural gas after adsorption, that is, the adsorption time may be adjusted according to the specific situation of the impurities, so that the gas after adsorption can better meet the requirement; this embodiment can carry out abundant absorption to the impurity in the raw materials natural gas better, improves the efficiency and the life of adsorbent, practices thrift the energy consumption.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.