CN103807158B - Micro-flow continuous adjustment system under high pressure - Google Patents

Abstract

The invention provides tiny flow quantity continuous adjustment system under high pressure, belong to high-pressure liquid transportation art.This system comprises cooling structure, high-pressure service pump structure for conveying, flow adjusting structure.Cooling structure comprises cooling coil and cryostat, and cooling coil is arranged in cryostat, and the front end of cooling coil is connected with external pipe, and the rear end of cooling coil is connected with one end of import threeway; High-pressure service pump structure for conveying is connected and composed successively by import threeway, import one-way valve, high-pressure service pump, outlet threeway, Outlet check valves, pressure meter three-way and delivery gauge; One end of import threeway is with cooling coil rear end or be directly connected external pipe, and one end of pressure meter three-way is connected with flow adjusting structure.Flow adjusting structure finely tunes metering valve by high pressure reset valve, high pressure and restrictor connects and composes successively; High pressure reset valve is connected with one end of outlet threeway, and restrictor is connected with import threeway in high-pressure service pump structure for conveying.Structure of the present invention is simple, and cost is low, has certain self-regulation ability.

Description

Micro-flow continuous adjustment system under high pressure

technical field

The invention relates to a micro-flow continuous adjustment system under high pressure, which belongs to the field of high-pressure fluid transportation.

Background technique

High-pressure plunger pumps, diaphragm pumps and other high-pressure pumps are widely used in high-pressure and ultra-high-pressure fields such as supercritical technology and liquefied petroleum gas. These high-pressure pumps can adjust the flow accurately by adjusting the stroke, but the flow adjustment range is limited, the stroke of the large flow is too small, the medium cannot be effectively conveyed, and the pressure cannot be directly controlled. In order to achieve flow regulation and ensure system safety, it is often necessary to install a high-pressure buffer tank and a safety valve behind the pump, and it is necessary to manually adjust the stroke or turn off the high-pressure pump to control or stabilize the flow and make the system run safely and stably. This solution is simple and feasible, but there are several major defects: (1) The high-pressure buffer tank has high cost, which increases the retention of raw materials, and when the pressure is particularly high, the compression coefficient of the medium increases, and the adjustment ability decreases significantly. For systems with very high pressure, this solution cannot meet the safety requirements. (2) The adjustment of pressure and flow requires manual intervention, and the response speed is slow, especially for emergencies such as system outlet blockage, etc., which cannot respond effectively, resulting in continuous increase in pressure, resulting in the opening of the safety valve and leakage of the conveying medium. When the medium is volatile Toxic, flammable, explosive, and corrosive media will cause huge damage. If the safety valve cannot be opened normally, there will be a danger of explosion. (3) The delivery flow rate of the large flow pump is small, causing uneven wear of the plunger and reducing the service life of the pump; when the stroke of the pump is too small, the medium cannot be sucked to achieve effective delivery, that is, the high flow high pressure pump cannot realize the small flow delivery of the medium . Chromatographic pumps or syringe pumps can realize the transmission of small flow and control of pressure, which completely overcomes the above defects, but they are expensive and greatly increase the cost of equipment.

Contents of the invention

In order to overcome the shortcomings of the traditional high-pressure pump-buffer tank pressure/flow adjustment system, the present invention proposes a small flow continuous adjustment system under high pressure, which adjusts the output flow through feedback of the return flow and outlet pressure. The structure is simple and the cost is low. The pump flow The effective combination of coarse adjustment + auxiliary fine adjustment system can replace expensive chromatographic pumps or syringe pumps with cheap plunger pumps/diaphragm pumps to achieve large flow (L/h), small flow (mL/min) and micro flow ( μL/min), that is, "one pump with multiple functions", and has a certain ability of automatic adjustment.

The technical solution of the present invention is to use backflow to adjust the outlet flow and pressure, and the flow can be automatically adjusted to a certain extent according to the outlet pressure. The system includes a cooling structure, a high-pressure pump delivery structure, and a flow adjustment structure. And the components in the structure are connected by pipelines.

The cooling structure includes a cooling coil and a low-temperature tank. The cooling coil is located in the low-temperature tank. The front end of the cooling coil is connected to an external pipe, and the rear end of the cooling coil is connected to one end of the inlet tee of the high-pressure pump delivery structure to play a cooling role. The low-temperature tank provides a cold source for the cooling coil, and the cooling structure is only used when the medium is liquefied gas.

The delivery structure of the high-pressure pump is composed of an inlet tee, an inlet check valve, a high-pressure pump, an outlet tee, an outlet check valve, a pressure gauge tee and an outlet pressure gauge; one end of the inlet tee is connected to the cooling coil of the cooling structure. The back end is connected or directly connected to the external pipeline, and one end of the pressure gauge tee is connected with the flow regulating structure.

The flow regulating structure is composed of a high-pressure fine-tuning valve, a high-pressure fine-tuning metering valve and a flow restrictor connected in sequence; the high-pressure fine-tuning valve is connected to one end of the outlet tee in the high-pressure pump delivery structure, and the flow limiter is connected to the inlet tee in the high-pressure pump delivery structure. The flow adjustment structure divides the output flow of the high-pressure pump, so as to realize the adjustment of the output flow of the system.

The pressure difference between the inlet and outlet of the high-pressure pump is relatively large, and in the high-pressure area, the medium pressure changes significantly with the medium density, so a small flow change may cause a large pressure change. The present invention uses three components of the flow adjustment system to jointly control the return flow , to ensure that the pump can adjust the pressure and flow under the premise of normal conveying medium. Among them, the high-pressure fine-tuning valve preliminarily adjusts the flow rate and controls the opening and closing of the bypass; the high-pressure fine-tuning metering valve realizes precise and micro-adjustment of the flow rate; the restrictor is used to increase the resistance of the pipeline and limit the return flow. , the diameter of the flow limiter should be much smaller than the diameter of the main pipeline. For the main flow of φ3 and φ6, the flow limiter should be 1/16 steel pipe. The length of the flow limiter coil is determined by the medium and the working pressure difference. The bigger the difference, the smaller the density and viscosity of the medium, the longer the coil.

The invention has a certain automatic adjustment ability. When the pump stroke and the opening of the flow regulating valve are constant, the return flow is related to the pressure difference between the front and back of the pump. The greater the pressure difference, the greater the return flow. Automatic control, when the pressure behind the pump increases, the return flow is automatically increased, thereby reducing the output flow. On the one hand, this is beneficial to the stability of the system, and on the other hand, it is beneficial to the safety of the system. In case of unexpected situations such as blockage of the system outlet, it can slow down the increase rate of the pressure behind the pump, and even limit the pressure before the safety valve is opened. promote. When the pressure increases too fast and exceeds the range of automatic flow adjustment, simply adjust the pressure and fine-tune the metering valve to quickly change the return flow, thereby limiting the pressure behind the pump and ensuring system safety.

Large-flow high-pressure plunger pumps and diaphragm pumps cannot transport media when the stroke is too small, but through the present invention, small-flow and micro-flow medium transportation can be realized, which is convenient and fast, and can protect the plunger from uneven wear, which is beneficial Pump maintenance. When precise flow control is not required, it can completely replace expensive chromatographic pumps and syringe pumps.

The invention has the advantages of simple structure, low cost and certain automatic adjustment ability, and can replace expensive chromatographic pumps or injection pumps with cheap plunger pumps/diaphragm pumps, and the flow adjustment is convenient and rapid.

Description of drawings

The accompanying drawing is a schematic diagram of a portable micro-flow continuous adjustment system under high pressure.

In the figure: 1 high pressure pump; 2 inlet check valve; 3 input medium inlet; 4 cooling coil; 5 low temperature tank;

6. Inlet tee; 7. Current limiter; 8. High-pressure fine-tuning metering valve; 9. High-pressure fine-tuning valve; 10. Outlet one-way valve; 11. Pressure gauge tee; 12. Transmission medium outlet;

detailed description

The specific implementation will be described in detail below in conjunction with the accompanying drawings.

Example

The cooling system consists of a cooling coil 4 and a low-temperature tank 5; the high-pressure pump delivery system consists of an inlet tee 6, an inlet check valve 2, a high-pressure pump 1, an outlet tee 13, an outlet check valve 10, a pressure gauge tee 11 and The outlet pressure gauge 14 is composed; the flow regulating system is composed of a high-pressure fine-tuning valve 9, a high-pressure fine-tuning metering valve 8 and a flow restrictor 7. For liquefied petroleum gas, carbon dioxide and other media, the upstream 3 of the system is connected to the cooling coil 4 of the cooling structure; for liquid media, the upstream 3 of the system is directly connected to the inlet tee 6 of the high-pressure pump delivery system. The inlet check valve 2 prevents the medium flowing back from the flow restrictor 6 from returning to the upstream 3 of the system. The medium entering from the one-way valve 2 enters the high-pressure pump 1 together with the medium returning from the restrictor 7 . After the medium is pressurized by the high-pressure pump, it is divided into two streams of fluid. The main flow enters the high-pressure pipeline through the outlet check valve 10. The outlet pressure gauge can monitor the outlet pressure and play a warning role; After the valve 8 and the flow restrictor 7, it returns to the pump inlet. Through these three components, the bypass has a significant pressure drop. The outlet pressure of the flow restrictor 7 is close to the pressure of the upstream 3 of the system, and the flow and pressure of the branch flow are mainly high pressure. The fine-tuning metering valve 8 is fine-tuned, and the high-pressure fine-tuning valve 9 plays the role of initially adjusting the flow rate and opening/closing the branch flow. The flow restrictor 7 increases the resistance of the bypass to ensure that the bypass has sufficient pressure drop.

Extract soybean oil with supercritical carbon dioxide, the operating pressure is 25MPa, the gas source is carbon dioxide gas cylinder, the pressure is about 5MPa, and the effective volume of the extractor is 100mL. There is a high-pressure plunger pump with a flow rate of 8L/h, the flow rate is too large for the extraction operation, and the reduction of the pump stroke will easily cause uneven wear of the plunger, and the flow adjustment is inconvenient; the system outlet flow is blocked by dry ice The valve port is not stable, so the pressure of the extractor fluctuates greatly. It is necessary to adjust the stroke of the pump or even shut down the pump to prevent the extractor from overpressure. Use a portable small/micro-flow continuous adjustment system under high pressure to transform the original system, connect the carbon dioxide cylinder to the cooling coil 4, and connect one end of the pressure gauge tee to the extractor. When in use, the stroke of the pump is fixed at an appropriate size, and the output flow is controlled through the high-pressure fine-tuning metering valve 8 and the high-pressure fine-tuning valve 9 . After using this device, the flow adjustment is convenient. Close the high-pressure fine-tuning valve 9 in the boosting stage, and use a large flow to make the pressure quickly reach the required value; open the high-pressure fine-tuning valve 9 in the extraction stage, and use the high-pressure fine-tuning metering valve 8 to adjust the flow of carbon dioxide. , The output flow is small, stable, and easy to adjust. The pressure fluctuation caused by the dry ice blockage of the outlet is improved due to the automatic adjustment function of the device, so that the pressure fluctuates between 22-28MPa without overpressure.

Claims (2)

1. a tiny flow quantity continuous adjustment system under high pressure, is characterized in that, this system comprises cooling structure, high-pressure service pump structure for conveying, flow adjusting structure, is connected between each structure and in structure between each parts by pipeline;

Cooling structure comprises cooling coil and cryostat, and cooling coil is arranged in cryostat, and the front end of cooling coil is connected with external pipe, and the rear end of cooling coil is connected with one end of the import threeway of high-pressure service pump structure for conveying; Cooling structure only uses when medium is liquid gas;

High-pressure service pump structure for conveying is connected and composed successively by import threeway, import one-way valve, high-pressure service pump, outlet threeway, Outlet check valves, pressure meter three-way and delivery gauge; One end of import threeway is connected with the cooling coil rear end of cooling structure or directly connects external pipe, and one end of pressure meter three-way is connected with flow adjusting structure;

Flow adjusting structure finely tunes metering valve by high pressure reset valve, high pressure and restrictor connects and composes successively; High pressure reset valve is connected with one end of high-pressure service pump structure for conveying middle outlet threeway, and restrictor is connected with import threeway in high-pressure service pump structure for conveying.

2. tiny flow quantity continuous adjustment system under high pressure according to claim 1, is characterized in that, described high-pressure service pump is high-pressure plunger metering pump or high-pressure diaphragm pump.