Multi-inlet and multi-outlet total control flow distribution method

Abstract

The invention discloses a multi-inlet and multi-outlet master control flow distribution method. The method comprises the following steps: constructing a multi-inlet and multi-outlet oil tank flow distribution system based on master control; according to the actual condition of the ship, an oil tank heating database is established, and the opening degree of a dynamic flow adjusting valve is determined; the database comprises the oil tank number, the heating temperature, the oil tank initial liquid level, the pipeline and the equipment resistance on the pipeline, the circulating oil pump lift and the oil density change before and after heat exchange; and the oil tank is heated according to the opening degree set by the dynamic flow regulating valve in the database, and the oil tank heating database is corrected according to detected data during operation. By means of the oil tank heating monitoring automatic control module, feasibility and safety of heating of the multiple oil tanks are guaranteed, when the oil tanks with different distances from the header pipe are heated at the same time, the flow of oil entering and flowing out is close, the automatic control function of oil tank heating is achieved, the heating efficiency of the multiple oil tanks is improved, and the working intensity and difficulty of sailors are reduced.

Description

Technical Field

[0001] The invention relates to a multi-inlet and multi-outlet total control flow distribution method, belonging to the field of oil tank heating. Background Art

[0002] When supply ships, oil tankers and other ships transport high-viscosity oil products, such as diesel and other finished oil products, this fluid is difficult to handle at room temperature due to its high viscosity. In order to ensure smooth unloading and replenishment, the viscosity of the cargo oil must be reduced by heating. Steam coils are usually used to increase the temperature of these liquids and reduce their viscosity to obtain fluids with higher fluidity so that they can be pumped to the designated location.

[0003] like Figure 1 As shown, two steam pipelines 3 are connected to two oil pipelines 4 through a heat exchanger 2, and each oil pipeline 4 is respectively connected to each oil tank 9. A fixed-frequency circulating oil pump 10 is provided on an oil pipeline 4 connected to the outlet of each oil tank 9, and another fixed-frequency circulating oil pump 10 is connected in parallel at both ends of the fixed-frequency circulating oil pump 10. The inlet of each oil tank 9 is connected to another oil pipeline 4 through a stop valve 6.

[0004] When it comes to heating multiple oil tanks under a multi-inlet and multi-outlet master control, there will be certain problems with the multi-inlet and multi-outlet master control form. When it comes to heating multiple oil tanks, there are generally two heating methods: one is to control the opening and closing of the inlet and outlet valves of the oil tanks, and heat the oil tanks one by one in a certain order. The advantage of this method is that there is no need to consider the hydraulic balance problem, and it is easier to achieve control in terms of reliability. However, the biggest disadvantage of this method is the low heating efficiency, and the circulating oil pump is in a low-load operation state for a long time, which is inefficient, increases operating costs, and cavitation is prone to occur in the pump body, reducing the sealing, thereby reducing the service life of the circulating oil pump. The other method is to open the inlet and outlet valves of all oil tanks and heat the oil in the oil tanks at the same time. Although this method improves the heating efficiency of the oil tanks, due to the hydraulic characteristics of the pipeline network, it causes hydraulic imbalance of the entire system. Hydraulic imbalance will cause two problems:

[0005] (1) Due to the difference in hydraulic characteristics of the pipeline network, the oil tanks close to the main pipe have stronger hydraulic characteristics than other oil tanks far away, and there is a large difference in the oil flow rate entering and flowing out of the oil tanks, resulting in excessive oil in the oil tanks close to the main pipe, exceeding the initial unheated liquid level, and even overflowing from the oil tank;

[0006] (2) Changes in the amount of oil in the tanks result in inconsistent temperatures in the various tanks, resulting in overheating or underheating of a tank;

[0007] (3) The operating conditions of the oil tank heating system are constantly changing. For example, the change in the number of oil tanks that need to be heated causes the flow in the main pipe to change. The system needs to have a certain adjustment capability to achieve efficient and stable heating of the oil tanks under multiple operating conditions.

[0008] Based on the above analysis, it can be seen that in order to ensure that multiple oil tanks are heated efficiently at the same time and that the heating temperatures of each oil tank are relatively consistent, it is necessary to construct a multi-inlet and multi-outlet total control flow allocation method to solve the problem that existing resources cannot be fully put into operation and ensure the safe operation of the entire system. Summary of the invention

[0009] The technical problem to be solved by the present invention is: how to ensure that multiple oil tanks are heated simultaneously with high efficiency and that the heating temperatures of the oil tanks are relatively consistent.

[0010] In order to solve the above technical problems, the technical solution of the present invention is to provide a method for allocating total control flow with multiple imports and exports, which is characterized by comprising the following steps:

[0011] Step 1: Construct a multi-inlet and multi-outlet oil tank flow distribution system based on master control: The flow distribution system includes

[0012] The power module provides power for the entire oil circulation heating;

[0013] The heat exchange module provides heat source for heating the oil tank module to ensure that the oil in the oil tank module is heated to the set temperature;

[0014] The oil tank module is a large space compartment for storing oil. The oil tank module includes multiple oil tanks;

[0015] Pipeline module is a pipeline system connecting various modules;

[0016] Monitor the automatic control module to ensure that the total amount of oil in each tank remains unchanged before and after heating;

[0017] The input end of the power module is connected to the oil tank module through the pipeline module, the output end of the power module is connected to the input end of the heat exchange module, and the output end of the heat exchange module is connected to the pipeline module;

[0018] Step 2: According to the actual situation of the ship, establish an oil tank heating database and determine the opening of the dynamic flow control valve; the database includes the number of oil tanks, heating temperature, initial liquid level of the oil tank, pipeline and equipment resistance on the pipeline, circulating oil pump head, and oil density changes before and after heat exchange;

[0019] Step 3: Heat the oil tank according to the opening set by the dynamic flow control valve in the database, and modify the oil tank heating database according to the detected data during operation.

[0020] Preferably, the power module is one or more circulating oil pumps, the input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is connected to the heat exchange module; the heat exchange module is a heat exchanger, the input end of the heat exchanger is connected to the circulating oil pump, the circulating oil pump transports the oil in the oil tank to the heat exchanger, and the output end of the heat exchanger is connected to the oil main pipe; according to the number of oil tanks, the pipeline module is divided into multiple branches, and each branch pipe converges to a main pipe, which circulates continuously under the power provided by the power module.

[0021] Preferably, the monitoring automatic control module includes pressure monitoring equipment arranged at the inlet and outlet of the oil tank, and a flow meter and a dynamic flow regulating valve arranged on the branch pipe entering the oil tank.

[0022] Preferably, the steps for correcting the oil tank heating database are as follows: select several typical heating conditions, perform operation debugging, debug the dynamic flow regulating valve, use the pressure gauges and import flow meters at the oil tank inlet and outlet, and measure the pressure and flow data under the conditions of simultaneous heating of different numbers of oil tanks; calculate the relationship between the pressure loss and the actual flow rate based on the measurement results, and correct the resistance loss curve under the database simulation state.

[0023] Preferably, the monitoring automatic control module further comprises a liquid level monitoring device arranged inside the oil tank; in order to ensure that the oil tank liquid level is at a safe level when the dynamic flow control valve fails to adjust, a liquid level monitoring device is arranged in each oil tank, and the monitoring liquid level index is Z * , when the liquid level reaches Z * The alarm starts and the heating of the oil tank is stopped.

[0024] Preferably, according to the oil tank module parameters, the number of oil tanks is N, and the ship oil tanks are numbered and represented as O 1 , O 2 ,…,O i ,…,O N ; Where N ≥ 2; Determine the time required to heat an oil tank, and determine the oil tank inlet branch flow Q according to the time requirement; The initial liquid level of each oil tank: Z 1 , Z 2 , …, Z i , …, Z N ; Where N≥2; Before and after the heat exchange module, after heating, the density of the oil will change. The corresponding density value is found according to the heating temperature T. The density change of the oil before and after heating is Δρ; Due to the change in the density of the oil before and after heating, if the total mass of the oil tank remains unchanged before and after heating, the liquid level of the oil tank will change. The liquid level of the oil tank after heating is Z * , Z * =f(Δρ,Z).

[0025] Preferably, the oil tank heating has multiple working conditions. According to the number of oil tank heating conditions, there are a total of M possible working conditions.

[0026] Preferably, the pipeline model is established by using FLOWMASTER to perform fluid calculation and analysis under all possible working conditions of oil tank heating.

[0027] Preferably, the circulating oil pump adopts a variable frequency circulating oil pump, and the head H of the circulating oil pump changes according to the change of the conveying flow rate; due to the change in the number of heating oil tanks, the flow in the same pipeline main pipe changes, the pipeline resistance ∑δ will also change accordingly, and a resistance loss curve is drawn.

[0028] Preferably, the flow rate of oil entering the oil tank is controlled by a dynamic flow regulating valve, and the opening of the dynamic flow regulating valve is adjusted with Q as the target flow rate; the opening P of the dynamic flow regulating valve at the inlet of a certain oil tank i Is related to the oil tank level Z * , circulating oil pump head H, pipeline resistance ∑δ factors are closely related, so P i =f(Z * ,H,∑δ)=f(Δρ,Z,H,∑δ).

[0029] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0030] 1. The present invention ensures the feasibility and safety of heating multiple oil tanks through the oil tank heating monitoring automatic control module.

[0031] 2. The present invention uses an oil tank heating monitoring automatic control module to achieve similar oil flow rates when oil tanks at different distances from the main pipe are heated at the same time.

[0032] 3. Ensure that the heating temperature of each oil tank is consistent, and solve the problem of overheating or insufficient heating in traditional oil tank heating.

[0033] 4. The present invention realizes the automatic control function of oil tank heating through the oil tank heating monitoring automatic control module, improves the efficiency of heating multiple oil tanks, and reduces the work intensity and difficulty of crew members. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a heating principle diagram of the general control mode of the oil tank heating system in the prior art;

[0035] Figure 2 A heating principle diagram of a multi-inlet and multi-outlet total control flow distribution method provided by the present invention;

[0036] Figure 3The present invention provides a flowchart of a method for distributing total controlled flow with multiple imports and exports. DETAILED DESCRIPTION

[0037] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0038] The present invention provides a method for distributing total control flow in a multi-inlet and multi-outlet oil tank heating system, such as Figure 2 As shown, it includes the following steps:

[0039] First, a multi-inlet and multi-outlet oil tank flow distribution system based on total control is constructed:

[0040] The system includes a power module, a heat exchange module, an oil tank module, a pipeline module and a monitoring automatic control module;

[0041] The power module provides power for the circulation heating of the entire oil, which can be one or more circulating oil pumps. In this embodiment, there are two variable frequency circulating oil pumps 1. The input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is a heat exchange module; the heat exchange module provides a heat source for heating the oil tank 9 to ensure that the oil in the oil tank 9 is heated to a set temperature. In this embodiment, it is a heat exchanger 2 with steam as a heat source. The input end of the heat exchanger 2 is connected to the circulating oil pump. The circulating oil pump transports the oil in the oil tank 9 to the heat exchanger 2. The output end of the heat exchanger 2 is connected to the oil main pipe; the oil tank module is a large storage tank for storing oil. The volume and number of the space compartments and the oil tanks 9 are determined according to the actual design of the ship. In this embodiment, there are three oil tanks 9; the pipeline module is a pipeline system connecting each module. It is divided into multiple branches according to the number of oil tanks 9. Each branch pipe converges into a main pipe and circulates continuously under the power provided by the power module; the monitoring automatic control module is provided with pressure monitoring equipment at the inlet and outlet of the oil tanks 9 to ensure that the total amount of oil in each oil tank 9 remains unchanged before and after heating, a flow meter 8 and a dynamic flow regulating valve 7 are provided on the branch pipe entering the oil tank 9, and a liquid level monitoring device is provided inside the oil tank 9.

[0042] In this embodiment, two steam pipelines 3 are connected to two oil pipelines 4 through a heat exchanger 2, and each oil pipeline 4 is respectively connected to each oil tank 9. A variable frequency circulating oil pump 1 is provided on an oil pipeline 4 connected to the outlet of each oil tank 9, and another variable frequency circulating oil pump 1 is connected in parallel at both ends of the variable frequency circulating oil pump 1. The inlet of each oil tank 9 is connected to another oil pipeline 4 through a stop valve 6. A dynamic flow regulating valve 7 is provided on the pipeline where the stop valve 6 is located and between the stop valve 6 and the oil tank 9. A flow meter 8 is provided between the dynamic flow regulating valve 7 and the oil tank 9, and a pressure gauge 5 is provided on the pipeline where the stop valve 6 is located and at the end of the stop valve 6 away from the oil tank 9.

[0043] In the whole process of implementing the heating task of oil tank 9, usually Figure 3The specific steps for implementing the process shown are as follows:

[0044] According to the actual situation of the ship, an oil tank heating database is established. The database includes: at the beginning of the ship design, the heating demand of the oil tank 9 (including the number of oil tanks 9, heating temperature, etc.), the initial liquid level of the oil tank 9, the resistance of the pipeline and the equipment on the pipeline, the head of the circulating oil pump, the change of oil density before and after heat exchange, etc.; according to the oil tank module parameters, the number of oil tanks 9 is 3, and the ship's oil tanks 9 are numbered, respectively represented as O1, O2, O3; according to the ship's heating demand, the selection of circulating oil pumps, economic efficiency and other considerations, the time required to heat an oil tank 9 will be determined, and the oil tank 9 inlet branch flow Q can be determined according to the time requirement; the initial liquid level of each oil tank 9: Z1, Z2, Z3; before and after the heat exchanger 2, after heating, the density of the oil will change, and the corresponding density value can be found according to the heating temperature T. The change of oil density before and after heating is Δρ; due to the change in oil density before and after heating, if the total mass of the oil tank 9 before and after heating remains unchanged, the liquid level of the oil tank 9 will change, and the liquid level of the oil tank 9 after heating is Z * , Z * =f(Δρ,Z).

[0045] There are many working conditions for heating the oil tank 9. According to the calculation of the number of heated oil tanks 9, the formula It can be calculated that there are 4 types of working conditions for heating more than 2 oil tanks 9. The circulating oil pump adopts a variable frequency circulating oil pump 1, and the head H of the circulating oil pump changes according to the change of the delivery flow rate; the pipeline model is established by FLOWMASTER, and the fluid calculation analysis of the 4 working conditions of heating the oil tank 9 can be performed. Due to the change in the number of heated oil tanks 9, the flow in the same pipeline main pipe changes. The pipeline resistance ∑δ under the 4 working conditions is calculated and the resistance loss curve under different working conditions is drawn. Corresponding to the resistance of the 4 different working conditions, the head H of the variable frequency circulating oil pump 1 is determined accordingly; the flow rate of oil entering the oil tank 9 is controlled by the dynamic flow regulating valve 7, and the opening of the dynamic flow regulating valve 7 is adjusted with Q as the target flow rate; the opening P of the dynamic flow regulating valve 7 at the inlet of a certain oil tank 9 i Is related to the oil tank 9 liquid level Z * , circulating oil pump head H, pipeline resistance ∑δ and other factors are closely related. According to the formula P i =f(Z * ,H,∑δ)=f(Δρ,Z,H,∑δ), the opening of the dynamic flow control valve 7 of the heating oil tank 9 under the four working conditions can be calculated.

[0046] According to the actual task requirements, a certain heating condition is selected, and the oil tank 9 is heated according to the opening set by the dynamic flow control valve 7 in the database. During operation, the oil tank heating database is corrected according to the detected pressure, flow and other data:

[0047] Several typical heating conditions are selected for operation debugging. The dynamic flow regulating valve 7 is debugged. The pressure gauges 5 at the inlet and outlet of the oil tank 9 and the inlet flow meter 8 are used to measure the pressure and flow data under the condition of simultaneous heating of different numbers of oil tanks 9. The relationship between the pressure loss and the actual flow is calculated based on the measurement results, and the resistance loss curve under the database simulation state is corrected.

[0048] In order to ensure that the liquid level of the oil tank 9 is at a safe level when the dynamic flow control valve 7 fails to adjust, a liquid level monitoring device 11 is set in each oil tank 9, and the monitoring liquid level index is Z * , when the liquid level reaches Z * The alarm starts and the heating of the oil tank 9 is stopped.

Claims

1. A method for allocating total control flow with multiple inlets and outlets, characterized in that: The following steps are involved: Step 1: Construct a multi-inlet and multi-outlet oil tank flow distribution system based on master control: The flow distribution system includes The power module provides power for the entire oil circulation heating; The heat exchange module provides heat source for heating the oil tank module to ensure that the oil in the oil tank module is heated to the set temperature; The oil tank module is a large space compartment for storing oil, and the oil tank module includes a plurality of oil tanks (9); Pipeline module is a pipeline system connecting various modules; A monitoring automatic control module is used to ensure that the total amount of oil in each oil tank (9) remains unchanged before and after heating; The input end of the power module is connected to the oil tank module through the pipeline module, the output end of the power module is connected to the input end of the heat exchange module, and the output end of the heat exchange module is connected to the pipeline module; Step 2: According to the actual situation of the ship, establish an oil tank heating database and determine the opening of the dynamic flow control valve (7); the database includes the number of oil tanks (9), heating temperature, initial liquid level of the oil tank (9), pipeline and equipment resistance on the pipeline, circulating oil pump head, and oil density change before and after heat exchange; Step 3: Heat the oil tank (9) according to the opening set by the dynamic flow control valve (7) in the database, and modify the oil tank heating database according to the detected data during operation.

2. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 1, characterized in that: The power module is one or more circulating oil pumps, the input end of the circulating oil pump is connected to the oil main pipe, and the output end of the circulating oil pump is connected to the heat exchange module; the heat exchange module is a heat exchanger (2), the input end of the heat exchanger (2) is connected to the circulating oil pump, the circulating oil pump transports the oil in the oil tank (9) to the heat exchanger (2), and the output end of the heat exchanger (2) is connected to the oil main pipe; according to the number of oil tanks (9), the pipeline module is divided into a plurality of branch pipes, and each branch pipe is connected to a main pipe, and circulates continuously under the power provided by the power module.

3. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 1, characterized in that: The monitoring automatic control module comprises a pressure monitoring device arranged at the inlet and outlet of the oil tank (9), a flow meter (8) and a dynamic flow regulating valve (7) arranged on a branch pipe entering the oil tank (9).

4. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 3, characterized in that: The steps for correcting the oil tank heating database are as follows: selecting several typical heating conditions, performing operation debugging, debugging the dynamic flow control valve (7), using the pressure gauges (5) and the inlet flow meter (8) at the inlet and outlet of the oil tank (9), and measuring the pressure and flow data under the conditions of simultaneous heating of different numbers of oil tanks (9); calculating the relationship between the pressure loss and the actual flow according to the measurement results, and correcting the resistance loss curve under the database simulation state.

5. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 3, characterized in that: The monitoring automatic control module further comprises a liquid level monitoring device arranged inside the oil tank (9); in order to ensure that the liquid level of the oil tank (9) is at a safe level when the dynamic flow control valve (7) fails to adjust, a liquid level monitoring device (11) is arranged in each oil tank (9), and the monitoring liquid level index is Z * , when the liquid level reaches Z * The alarm is triggered and heating of the oil tank (9) is stopped.

6. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 1, characterized in that: According to the oil tank module parameters, the number of oil tanks (9) is N, and the ship oil tanks (9) are numbered and represented as O1, O2, ..., O i ,…,O N ; Wherein, N≥2; Determine the time required to heat an oil tank (9), and determine the flow rate Q of the inlet branch pipe of the oil tank (9) according to the time requirement; The initial liquid level of each oil tank (9): Z1, Z2, ..., Z i , …, Z N ; Wherein, N≥2; before and after the heat exchange module, after heating, the density of the oil will change, and the corresponding density value is found according to the heating temperature T. The density change of the oil before and after heating is Δρ; due to the change in the density of the oil before and after heating, if the total mass of the oil tank (9) before and after heating remains unchanged, the liquid level of the oil tank (9) changes, and the liquid level of the oil tank (9) after heating is Z * , Z * =f(Δρ,Z).

7. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 6, characterized in that: There are multiple operating conditions for heating the oil tank (9). According to the number of heated oil tanks (9), there are a total of M possible operating conditions. (N≥i≥2,N≥2).

8. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 7, characterized in that: The pipeline model is established by using FLOWMASTER to perform fluid calculation analysis under all possible working conditions of heating the oil tank (9).

9. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 6, characterized in that: The circulating oil pump adopts a variable frequency circulating oil pump (1), and the head H of the circulating oil pump changes according to the change of the conveying flow rate; due to the change in the number of heating oil tanks (9), the flow rate in the same pipeline main pipe changes, and the pipeline resistance ∑δ will also change accordingly, and a resistance loss curve is drawn.

10. A method for allocating total control flow with multiple inlets and outlets as claimed in claim 6, characterized in that: The flow rate of oil entering the oil tank (9) is controlled by a dynamic flow regulating valve (7), and the opening of the dynamic flow regulating valve (7) is adjusted with Q as the target flow rate; the opening P of the dynamic flow regulating valve (7) at the inlet of a certain oil tank (9) i is related to the oil tank (9) liquid level Z * , circulating oil pump head H, pipeline resistance ∑δ factors are closely related, so P i =f(Z * ,H,∑δ)=f(Δρ,Z,H,∑δ).

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