阅读说明：本技术 一种lpg泵串联控制系统及其控制方法 (LPG pump series control system and control method thereof ) 是由 刘红波 于永东 李玉忠 郭春雷 王钰 孙雪莹 李�东 刘清华 李晓赟 于 2020-12-16 设计创作，主要内容包括：本发明涉及石油石化的物料输送技术领域,公开了一种LPG泵串联控制系统及其控制方法；控制系统,包括：前泵,后泵,入口通过输送管路与前泵的出口相连通；温度检测件,设置在后泵的入口,用于检测后泵入口温度；压力检测件,其设置在后泵的入口,用于检测后泵入口压力；调节阀,设置在后泵的下游,调节调节阀的开度能够调节后泵入口压力；计算机自动控制系统,后泵、温度检测件、压力检测件及调节阀均与计算机自动控制系统电连接,计算机自动控制系统能够根据后泵入口温度计算实时饱和蒸气压,控制后泵的关闭及调节阀的开度。计算机自动控制系统根据实时饱和蒸气压确定工作状态,避免后泵被气蚀,无需缓冲罐,减少了投资及输送物料的能耗。(The invention relates to the technical field of material conveying of petroleum and petrochemical industry, and discloses an LPG pump series control system and a control method thereof; a control system, comprising: the inlet of the front pump and the inlet of the rear pump are communicated with the outlet of the front pump through a conveying pipeline; the temperature detection piece is arranged at the inlet of the rear pump and used for detecting the temperature of the inlet of the rear pump; a pressure detecting member provided at an inlet of the rear pump for detecting a rear pump inlet pressure; the regulating valve is arranged at the downstream of the rear pump, and the opening of the regulating valve can be regulated to regulate the inlet pressure of the rear pump; the computer automatic control system is electrically connected with the rear pump, the temperature detection piece, the pressure detection piece and the regulating valve, and can calculate the real-time saturated vapor pressure according to the inlet temperature of the rear pump and control the closing of the rear pump and the opening of the regulating valve. The computer automatic control system determines the working state according to the real-time saturated vapor pressure, avoids the back pump from being cavitated, does not need a buffer tank, and reduces the investment and the energy consumption for conveying materials.)

1. An LPG pump series control system, comprising:

a front pump (1);

the inlet of the rear pump (2) is communicated with the outlet of the front pump (1) through a conveying pipeline;

a temperature detection member (3) provided at an inlet of the rear pump (2) for detecting a temperature of the inlet of the rear pump (2);

a pressure detecting member (4) provided at an inlet of the rear pump (2) for detecting a pressure at the inlet of the rear pump (2);

a regulating valve (5) arranged downstream of the rear pump (2) for regulating the opening of the regulating valve (5) to regulate the pressure at the inlet of the rear pump (2);

the automatic control system of the computer (6), the rear pump (2), the temperature detection piece (3), the pressure detection piece (4) and the regulating valve (5) are all electrically connected with the automatic control system of the computer (6), the automatic control system of the computer (6) can calculate the real-time saturated vapor pressure according to the temperature of the inlet of the rear pump (2), and can also control the closing of the rear pump (2) and control the opening degree of the regulating valve (5).

2. LPG pump series control system according to claim 1, characterized in that the regulating valve (5) is arranged on the outlet of the rear pump (2).

3. LPG pump series control system according to claim 1, characterized in that the regulating valve (5) is arranged on the delivery line to which the outlet of the rear pump (2) is connected.

4. LPG pump series control system according to claim 1, characterized in that the regulating valve (5) is an electrically controlled valve.

5. LPG pump series control system according to claim 1, characterized in that the pressure detection member (4) is a pressure sensor.

6. LPG pump series control system according to claim 1, characterized in that the temperature detection means (3) is a temperature sensor.

7. A control method of an LPG pump series control system, which is directed to the LPG pump series control system as set forth in any one of claims 1 to 6, comprising the steps of:

s1, calculating a real-time saturated vapor pressure by the automatic computer control system (6) according to the temperature of the inlet of the rear pump (2);

and S2, determining the opening of the regulating valve (5) and the working state of the rear pump (2) by the automatic control system (6) of the computer according to the pressure at the inlet of the rear pump (2) and the real-time saturated vapor pressure.

8. The control method of an LPG pump series control system as set forth in claim 7, wherein step S0 is included before step S1, the temperature of the inlet of the rear pump (2) is detected, and the pressure of the inlet of the rear pump (2) is detected.

9. The control method of an LPG pump series control system according to claim 8, characterized in that step S2 includes:

s21, judging whether the pressure of the inlet of the rear pump (2) is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the safety allowance, and if not, executing the step S22;

s22, judging whether the pressure at the inlet of the rear pump (2) is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the minimum safety allowance, if not, closing the rear pump (2); if yes, the opening degree of the regulating valve (5) is adjusted to be small, the pressure of the inlet of the rear pump (2) is detected, and the step S1 is repeated until the pressure of the inlet of the rear pump (2) is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the safety allowance.

Technical Field

The invention relates to the technical field of petroleum and petrochemical material conveying, in particular to an LPG (liquefied petroleum gas) pump series control system and a control method thereof.

Background

In the field of petrochemistry, LPG (liquefied gas) is a common material, and the transportation process of LPG materials is widely applied to device feeding, loading and unloading ships, loading and unloading vehicles and other process systems. Under some working conditions (such as ship unloading) that the lift of a single pump is insufficient, the LPG material is conveyed by the serial connection of the pumps.

When pumps are operated in series, the inlet pressure of the rear pump needs to be controlled to prevent pump-out. The inlet pressure of the rear pump is always larger than the sum of the necessary cavitation allowance of the pump and the saturated vapor pressure of the material, so that the pump is prevented from being cavitated.

However, for LPG materials, the saturated vapor pressure of the materials is greatly influenced by the temperature, the adjusting parameter cannot be set to a certain constant value, and the series control of pumps is difficult to realize. In the prior art, a buffer tank is usually arranged between the front pump and the rear pump, but the mode has large investment and high energy consumption.

Therefore, an LPG pump series control system and a control method thereof are needed to solve the above technical problems.

Disclosure of Invention

The invention aims to provide an LPG (liquefied petroleum gas) pump series control system and a control method thereof, which can determine the working state according to the real-time saturated vapor pressure and avoid the cavitation erosion of a rear pump; and a buffer tank is not required, so that the investment cost is reduced and the energy consumption of the pump for conveying materials is reduced.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, there is provided an LPG pump series control system comprising:

a front pump, a back pump and a front pump,

the inlet of the rear pump is communicated with the outlet of the front pump through a conveying pipeline;

a temperature detecting member provided at an inlet of the rear pump for detecting a temperature of the inlet of the rear pump;

a pressure detecting member provided at an inlet of the rear pump for detecting a pressure of the inlet of the rear pump;

a regulating valve disposed downstream of the rear pump for regulating an opening of the regulating valve to regulate a pressure of the rear pump inlet;

the automatic control system of computer, back pump, temperature detection spare, pressure detection spare and governing valve all with automatic control system of computer electricity is connected, automatic control system of computer can be according to the temperature calculation real-time saturated vapour pressure of back pump entry, can also control closing of back pump and control the aperture of governing valve.

As a preferable technical scheme of the series control system of the LPG pump, the regulating valve is arranged on the outlet of the rear pump.

As a preferable technical scheme of the series control system of the LPG pump, the regulating valve is arranged on a conveying pipeline connected with the outlet of the rear pump.

As a preferred technical scheme of the series control system of the LPG pump, the regulating valve is an electric control valve.

As a preferable technical scheme of the series control system of the LPG pump, the pressure detection piece is a pressure sensor.

As a preferable technical scheme of the series control system of the LPG pump, the temperature detection piece is a temperature sensor.

In a second aspect, there is provided a control method of an LPG pump series control system, which is directed to the LPG pump series control system as described above, the control method comprising the steps of:

s1, calculating a real-time saturated vapor pressure by the automatic control system of the computer according to the temperature of the inlet of the rear pump;

and S2, determining the opening of the regulating valve and the working state of the rear pump by the automatic control system of the computer according to the pressure at the inlet of the rear pump and the real-time saturated vapor pressure.

As a control method of the LPG pump series control system, a step S0 is included before the step S1, the temperature of the inlet of the rear pump is detected, and the pressure of the inlet of the rear pump is detected.

As a control method of the LPG pump series control system, step S2 includes:

s21, judging whether the pressure of the inlet of the rear pump is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the safety allowance, and if not, executing the step S22;

s22, judging whether the pressure of the inlet of the rear pump is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the minimum safety allowance, if not, closing the rear pump; if so, the opening of the regulating valve is adjusted to be small, the pressure of the rear pump inlet is detected, and the step S1 is repeated until the pressure of the rear pump inlet is larger than the sum of the saturated vapor pressure, the necessary cavitation allowance of the pump and the safety allowance.

The invention has the beneficial effects that: the computer automatic control system calculates real-time saturated vapor pressure according to the temperature detected by the temperature detection piece, and determines the opening of the regulating valve and the working state of the rear pump according to the pressure of the inlet of the rear pump and the real-time saturated vapor pressure so as to prevent the rear pump from being cavitated; and a buffer tank is not required, so that the investment cost is reduced and the energy consumption of the pump for conveying materials is reduced.

Drawings

FIG. 1 is a schematic structural diagram of an LPG pump tandem control system provided by the present invention;

FIG. 2 is a flow chart of a control method of the LPG pump series control system provided by the present invention.

In the figure: 1. a front pump; 2. a rear pump; 3. a temperature detection member; 4. a pressure detecting member; 5. adjusting a valve; 6. and (3) a computer automatic control system.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally placed when the products of the present invention are used, and are used only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the devices or elements to be referred to must have specific orientations, be constructed in specific orientations, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; either mechanically or electrically. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1, the present embodiment discloses an LPG pump series control system, which comprises a front pump 1, a rear pump 2, a temperature detecting member 3, a pressure detecting member 4, a regulating valve 5 and an automatic computer control system 6.

The inlet of the rear pump 2 is communicated with the outlet of the front pump 1 through a conveying pipeline, the outlet of the rear pump 2 is connected to the conveying pipeline, the rear pump 2 is used for conveying materials conveyed by the front pump 1, and the materials are conveyed away through the conveying pipeline connected with the outlet of the rear pump 2.

The rear pump 2, the temperature detection piece 3, the pressure detection piece 4 and the regulating valve 5 are all electrically connected with the automatic computer control system 6, and the automatic computer control system 6 can control the closing of the rear pump 2.

The temperature detection piece 3 is arranged at the inlet of the rear pump 2, the temperature detection piece 3 is used for detecting the temperature of the inlet of the rear pump 2 and feeding the detected value back to the automatic computer control system 6, and the automatic computer control system 6 calculates the real-time saturated vapor pressure according to the temperature of the inlet of the rear pump 2. Preferably, in the present embodiment, the temperature detector 3 is a temperature sensor.

The pressure detection part 4 is arranged at the inlet of the rear pump 2, and the pressure detection part 4 is used for detecting the pressure at the inlet of the rear pump 2 and feeding the detected value back to the automatic computer control system 6. Preferably, in the present embodiment, the pressure detecting member 4 is a pressure sensor.

The regulating valve 5 is provided downstream of the rear pump 2, specifically, the regulating valve 5 is provided on an outlet of the rear pump 2 or on a delivery line to which the outlet of the rear pump 2 is connected. In this embodiment, the regulating valve 5 is disposed on the delivery line to which the outlet of the rear pump 2 is connected, and the regulating valve 5 is preferably an electrically controlled valve. The computerized automatic control system 6 is able to control the opening of the regulating valve 5 to regulate the pressure at the inlet of the rear pump 2.

As shown in fig. 2, the present embodiment further discloses a control method of an LPG pump series control system, which is directed to the LPG pump series control system, and the control method includes the following steps:

s0, the temperature of the inlet of the pump 2 is detected by the temperature detection piece 3, and the detected value is fed back to the automatic control system 6 of the computer; the pressure detecting part 4 detects the pressure P of the inlet of the rear pump 2₁And feeds the detection value back to the computer automatic control system 6.

S1, calculating real-time saturated vapor pressure P by the computer automatic control system 6 according to the temperature of the inlet of the rear pump 2_T；

S2, the computer automatic control system 6 according to the pressure P of the inlet of the rear pump 2₁And real timeSaturated vapor pressure P_TThe opening degree of the regulator valve 5 and the operating state of the rear pump 2 are determined.

Wherein, step S2 includes:

s21, judging the pressure P at the inlet of the rear pump 2₁Whether or not it is greater than the saturated vapor pressure P_TPump necessary cavitation margin P_HNAnd a safety margin P_YSum P_CTo promptly judge P₁＞P_T+P_HN+P_Y(ii) a If so, the rear pump 2 cannot be cavitated, and the rear pump 2 normally operates; if not, go to step S22;

s22, judging the pressure P at the inlet of the rear pump 2₁Whether or not it is greater than the saturated vapor pressure P_TPump necessary cavitation margin P_HNAnd a minimum safety margin P_JSum P_STo promptly judge P₁＞P_T+P_HN+P_J(ii) a If not, the automatic control system 6 of the computer controls the pump 2 to be closed; if yes, the computer automatic control system 6 controls the opening degree of the regulating valve 5 to be reduced, and then step S0 is carried out until the pressure P at the inlet of the rear pump 2₁Greater than the saturated vapor pressure P_TPump necessary cavitation margin P_HNAnd a safety margin P_YThe rear pump 2 is not cavitated until the sum.

The embodiment is a LPG special berth propane ship unloading system. The berth is far away from the rear tank area, the lift of the ship unloading pump is insufficient, a ground pump and a ship pump are required to be arranged at the wharf and are connected in series, the ground pump is a rear pump 2, and the ship pump is a front pump 1.

The temperature of the inlet of the rear pump 2 is changed within the range of-42 ℃ to-18 ℃ under the influence of factors such as the environmental temperature, the conveying time and the like. The cavitation allowance of the rear pump 2 is 8m, namely 0.05 MPa; the safe residual quantity is 0.15MPa, and the minimum safe residual quantity is 0.05 MPa.

Under different working conditions, the control of the series pump group is as follows:

1. working condition 1: pressure P at inlet of rear pump 2₁0.4MPa, pump inlet temperature-40 ℃.

In this operating condition, P_T＝0.01MPa，P_C＝P_T+P_HN+P_Y＝0.01+0.05+0.15＝0.21MPa；P_S＝P_T+P_HN+P_J＝0.01+0.05+0.05＝0.11MPa，P₁＞P_C＞P_S(ii) a The tandem pump group can stably operate.

2. Working condition 2: pressure P at inlet of rear pump 2₁0.4MPa, pump inlet temperature-30 ℃.

In this operating condition, P_T＝0.07MPa，P_C＝P_T+P_HN+P_Y＝0.07+0.05+0.15＝0.26MPa；P_S＝P_T+P_HN+P_J＝0.07+0.05+0.05＝0.17MPa；P₁＞P_C＞P_SAnd the series pump set can stably operate.

3. Working condition 3: pressure P at inlet of rear pump 2₁0.4MPa, pump inlet temperature-20 ℃.

In this operating condition, P_T＝0.24MPa；P_C＝P_T+P_HN+P_Y＝0.24+0.05+0.15＝0.44MPa；P_S＝P_T+P_HN+P_J＝0.24+0.05+0.05＝0.34MPa，P_C＞P₁＞P_SThe computer automatic control system 6 sends out signals to reduce the opening of the regulating valve 5, so that the pressure at the inlet of the rear pump 2 is increased back to more than 0.44MPa, and the series pump set can stably run.

4. Working condition 4: pressure P at inlet of rear pump 2₁0.3MPa, pump inlet temperature-20 ℃.

In this operating condition, P_T＝0.24MPa，P_S＝P_T+P_HN+P_J＝0.24+0.05+0.05＝0.34MPa,P₁＜P_SAnd the automatic control system sends out a signal to shut down the rear pump 2, so that the rear pump 2 is prevented from being damaged by cavitation.

The computer automatic control system 6 calculates the real-time saturated vapor pressure according to the temperature detected by the temperature detection part 3, and determines the opening of the regulating valve 5 and the working state of the rear pump 2 according to the pressure at the inlet of the rear pump 2 and the real-time saturated vapor pressure, so as to avoid the cavitation erosion of the rear pump 2. The LPG pump series control system does not need to be provided with a buffer tank, so that the investment cost is reduced, and the energy consumption of the pump for conveying materials is reduced.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.