RU2418654C1 - Method of controlling gasostatic extruder gas drive and device to this end - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to powder metallurgy, particularly, to equipment for processing discrete or solid materials at combined or separate effects of gas pressure of up to 500 MPa and temperature of up to 2000C developed inside working chamber of gasostatic extruder. Proposed method comprises feeding gas into gas regulator mounted extruder gas drive suction pipeline to communicated high-pressure compressor with low-pressure compressor. The both compressors incorporate shut-off valves with unloading gas cylinder. Pressure regulator is made up of receiver furnished with pressure pickup and shut-off valve. With increasing pressure in extruder container, pressure equal or approximating to maximum suction pressure of high-pressure compressor is maintained in suction pipeline of said compressor. Note here that, with pressure drop of 5 MPa in high-pressure compressor suction pipeline, low-pressure compressor is switched on in response to receiver pressure pickup signal. Low-pressure compressor feeds gas to suction side of high-pressure compressor and to receiver. With pressure increasing in receiver and high-pressure compressor suction pipeline to maximum suction pressure, low-pressure compressor is switched off in response to receiver pressure pickup signal. Extruder gas drive control device comprises pressure regulator arranged on suction line communicating interacting high-pressure compressor with low-pressure compressor. Said pressure regulator consists of gas receiver provided with pressure pickup and shut-off valve. ^ EFFECT: faster development of preset pressure and execution of work cycles, decreased work cycle duration. ^ 2 cl, 2 dwg

Description

The invention relates to the field of creating industrial equipment for the processing of large-sized products from solid and discrete materials with simultaneous or combined exposure to high pressures and temperatures up to 500 MPa and temperatures up to 2000 ° C created in the gas environment of the working chamber of a gas thermostat.

The main components of the gas thermostat are:

- the actual gas thermostat, including a container with upper and lower plugs, as well as a power bed;

- gas and vacuum systems providing the necessary technological parameters of the gaseous medium in the working chamber of the machine;

- heating and cooling systems,

- as well as a control system.

The efficiency of a gas thermostat largely depends on the performance and reliability of its main gas system. In turn, the quality level of the latter is determined by the gas drive of the machine, namely the performance and circuitry of gas compressors, the capacity of their shut-off equipment and gas pipeline, as well as the design of the gas system itself.

An analogue of the invention is a gas thermostat described in the book by G. A. Krivonos, L. Yu. Maksimov, A. D. Zverev. "Processes and equipment for gas-static treatment." - M .: Metallurgy, 1994, p. 110, in which the gas drive control method and device for its implementation contain the following elements: gas and vacuum systems, the actual gas thermostat with heating system and cooling system, balloon station, compressor, control measuring equipment, pipelines and shut-off and control equipment of high pressure (shut-off valves with manual control). A significant drawback of the analogue drive is that to create pressure in the container, one compressor is used as the pressure source, installed directly between the balloon station and the working chamber, the maximum discharge pressure of which should be at least the technologically necessary working cycle pressure in the range 200-500 MPa It should be noted that creating pressures in excess of 200 MPa with a single compressor is almost impossible. With the indicated arrangement of components, namely: cylinders-compressor-working chamber, compressor productivity decreases sharply as its compression ratio increases - the ratio of discharge pressure to suction pressure, in this case equal to the ratio of increasing pressure in the container to the pressure in the cylinders. This increases the time required to create the pressure in the working chamber and the total time of the working cycle, and also reduces the performance of the gas thermostat.

The prototype of the invention is a gas thermostat described by RF patent No. 2350429 of 06/09/2007, in which the gas drive control method is as follows when the control device is in the form of a gas bath containing a container with plugs forming its working chamber, power bed, gas system, connected to the working chamber by a high pressure pipeline and equipped with shut-off and regulating equipment with a small nominal bore DN 3-5 mm, heating and cooling systems, as well as a control system, while gas ivod compressors equipped with low and high pressures with the possibility of simultaneous operation with maximum efficiency in the modes parallel and series connection through the installation between compressors needle-type pressure regulator.

The disadvantages of the method of controlling a gas drive and a device for its implementation include the use of a needle pressure regulator of a rather complicated design, equipped with disk springs of high rigidity and a movable needle with a block of its seals. The internal tightness of the regulator and its operability can be ensured only if a high degree of alignment of the diameters of the subvalvular cavity and the needle shaft is observed, as well as the lack of runout of the needle seating cone relative to the diameter of its shaft. The pressure regulator is installed on a small-volume pipeline connecting low and high pressure compressors, in which there is constant pulsation and gas pressure surges leading to the operation of the regulator. With frequent operation of the regulator, its sharp edge collapses and collapses under the force of the block of rigid disk springs during landing in the saddle of the hardened needle, the elements of the seal block wear out intensively and the high-pressure connections of the pipeline and equipment are weakened. As a result, regular frequent restoration of the working surfaces of the needle and the regulator seat, replacement of the worn-out seal block, and restoration of gas tightness are required.

The technical result of the invention is the creation of high-performance, reliable gas baths for processing industrial products from discrete, continuous and nanopowder materials with high (up to 500 MPa) gas pressure at temperatures up to 2000 ° C.

The technical result of the invention, which consists in:

- creating an effective gas system with increased working pressure;

- reducing the time of creating a given pressure in the container of the cycle;

- a significant reduction in its metal consumption and cost;

- increasing the productivity of the gas thermostat and reducing the cost of products,

is achieved by the fact that the gas drive of the machine includes low and high pressure compressors operating at maximum performance while turning them on, controlled by a gas receiver installed on the pipeline connecting the compressors, while supplying the gas system with a gas pipeline and compact equipment with increased nominal bore, made in in the form of a shut-off valve with a discharge cylinder.

The design of a gas thermostat with the gas drive control method of the invention is shown in FIG. 1, FIG. 2 shows the construction of a needle-type pressure regulator (prototype) as information material.

The gas thermostat contains a power frame 1, fastened with a bandage of high-strength tape 2, a container 3, closed at the ends of the upper 4 and lower 5 plugs, normally-closed valves with an increased passage 6, 7, 8 and 9, a gas compressor low 10 (KND) and high 11 (HPC) pressure, as well as a balloon station 12. HPP, as a rule, is made in the form of a two-stage unit.

To control the flow of the working medium during the technological operations of the working cycle, the valves 6, 7, 8 and 9 are interconnected and with other components of the gas system by a pipe 13, while the gas inlet 14 into the container 3 is made in the upper tube. A gas receiver 15 is installed on the pipeline connecting the compressors, equipped with its own manual shut-off valve 16, a safety valve 17, a pressure gauge 18, and a pressure gauge 19. The latter, if they are repaired or replaced, are cut off from the gas-filled receiver by shut-off valves 20 and 21, respectively.

In order to create an efficient gas drive, industrial gas thermostats with a large working chamber volume are equipped with low-pressure compressors, the performance of which is several times higher than the performance of high-pressure compressors operating sequentially when the pressure rises in the container. Therefore, it is impossible to synchronize or use their maximum performance under constantly changing suction and discharge pressures without the use of additional tools. Attempts to solve this problem include the use, as in the prototype, of a pressure regulator installed between KND and KVD.

In the proposed invention, the efficiency of the gas drive of the gas thermostat is ensured by the use of a gas receiver that controls the operation of high and low pressure compressors and installed between the compressors, while the high pressure compressor maintains a pressure equal to or close to the maximum suction pressure, the absence of dynamic load on the equipment and connections high pressure due to a smooth change in pressure in the KND-receiver-KVD system, as well as energy savings during periods of eskom CPV disconnected during pressure build-up in the working chamber gazostat. KND shutdown time is 40-50% less than the KVD operating time.

The gas drive gas thermostat operates as follows. In the initial position, the power frame 1 is shifted from the axis of the container 3. On the lower tube 5, which is in the lower position outside the container, the workpiece is installed and introduced into the working space of the gas thermostat chamber. Then the power bed is installed on the axis of the container.

During the preparatory work for the technological cycle, including loading the workpiece, the receiver 15 is filled with working gas. To do this, valve 9 is opened, and gas flows by gravity from the cylinders 12 into the receiver until the pressure in them is equalized, while valve 16 is open. Next, the KND 10 is turned on and raises the pressure in the receiver 15 to the value equal to the maximum suction pressure of the high-pressure pump 11. According to the sensor signal pressure 19 KND 10 stops, and valve 9 closes. Visually, the pressure in the receiver can be determined by a pressure gauge 18. The safety valve 17 installed on the receiver is set to a response pressure that is 10% higher than the suction pressure of the HPC. Then the valve 8 opens and the gas from the cylinders 12 by gravity enters the container 3. After equalizing the pressure in them, the valve 8 closes. Valve 7 opens, and KVD 11 is turned on, pumping gas from receiver 15 to container 3. When the pressure in the receiver drops by a predetermined amount (for example, by 5 MPa), valve 9 opens according to the signal from sensor 19 and KND 10 turns on, simultaneously supplying gas from cylinders into the receiver and suction the HPC, which pumps it into the container. Both compressors operate in series. When the pressure in the receiver 15 is equal to the maximum suction pressure of the HPC, the pressure sensor 19 stops the pressure switch and the valve 9 closes. KVD 11 continues to work, supplying gas from the receiver 15 to the container. When the pressure in the receiver decreases by a predetermined value according to the signal of the sensor 19, valve 9 opens and KND 10 is turned on. Next, the described sequence of operation of compressors and shut-off valves is repeated until the necessary pressure is created in the gas container, while the KVD works with maximum or close to her performance, and CPV is periodically disabled. The total time for creating the necessary pressure in the containers of industrial gas thermostats with a large volume of the working chamber reaches several hours. After that, the compressors stop, valves 7, 9 and valve 16 are closed. The heating system is turned on, heating the workpiece to the required temperature. At a given pressure and temperature, the workpiece is aged for the required time. Then the heating system is turned off, and the working space of the chamber with the workpiece is cooled. Valve 8 opens, and gas flows by gravity from container 3 into cylinders 12. The remaining gas is discharged through open valve 6 from the container to a low-pressure balloon station (not shown) or to the atmosphere. After reducing the pressure in the container to atmospheric, the power bed 1 moves from the axis of the container, releasing the lower plug 5, which together with the processed product is removed from it, and a new duty cycle can be carried out. The execution time of the next working cycle will be reduced by the amount necessary for the initial pressure increase in the receiver 15 using KND 10, since during the previous working cycle, it remained charged to a value that is in a narrow range of the accepted pressure change in the receiver.

Thus, equipping a gas thermostat gas drive with series-connected low and high pressure compressors, between which a gas receiver is installed, as well as normally-closed valves and a gas pipeline with an increased passage allows:

- create a reliable and high-performance gas thermostat with a large volume of the working chamber;

- reduce the execution time of work cycle operations related to moving the working medium between the components of the gas system using low and high pressure compressors operating at maximum capacity;

- reduce the total cycle time, increase the productivity of the gas bath and reduce the cost of products.

As an example of the gas drive of the gas thermostat, the calculation of the parameters is given on the following sheets.

When calculating the parameters of the gas drive of a gas thermostat, which consists in determining the volume of the receiver that ensures the efficient operation of low and high pressure compressors, and the ratio of the operating time of the low pressure and high pressure valves when the pressure in the container rises, the properties of gaseous nitrogen from the Gas Encyclopaedia, publisher " ELSEVIER ", 1976. The gas properties in the mentioned source are given at various pressures expressed in bars and temperatures in degrees Kelvin.

The following is a calculation of the parameters of the gas drive of a gas thermostat, which uses nitrogen gas as the working medium, and the drive is equipped with a low-pressure membrane compressor (KND) of the MKZ-19 brand (Hofer, Germany) with a nominal discharge pressure of pH ₁₀ = 350 bar, pressure the intake of PBC ₁₀ = 150 bar and with a capacity of Q ₁₀ = 520 nm ³ / h, as well as a high-pressure compressor (HPC) of the grade 6.3MK 200 / 350-1500 (Uralkompressor, Russia) with nominal discharge pressure Rn ₁₁ = 1500 bar , suction pressure PBC ₁₁ = 350 bar and a capacity of Q ₁₁ = 200 nm ³ / h In the calculation, the nominal values of capacities, suction and discharge pressures of the low pressure and high pressure valves, which are the passport characteristics of the units, were used.

To ensure the operation of KVD-11 with maximum productivity, which is possible with a suction pressure equal to PBC ₁₁ = 350 bar or close to it, we take the calculated pressure drop in the receiver to be 50 bar (from 350 to 300 bar) for a time τ ₁₁ = 5 minutes or 0.083 hours of operation of the HPC.

In 5 minutes (0.083 hours), the HPC will take the following amount of gas, expressed in normal cubic meters, from the receiver

which corresponds to the mass of nitrogen expressed by the formula

where ρ _n-11 = 1.12 kg / m ³ is the nitrogen density under environmental conditions, taken equal to: pressure P = 1 bar and temperature T = 300 K.

Using the equation of state of a real gas, the same mass of gas taken from the receiver can be calculated using the following expression

where the receiver volume is defined as

where P _15-1 = 350 bar and P _15-2 = 300 bar gas pressure in the receiver at the beginning and end of the selection of gas from it;

V ₁₅ - receiver volume, m ³ ;

Z ₁ = 1.1954 and Z ₂ = 1.1425 the compressibility factors of nitrogen at temperature

T = 300 K and a pressure of 350 and 300 bar, respectively;

T = 300 K is the ambient temperature;

R = 30.28 kgf / kg * K is the gas constant of nitrogen.

After reducing the pressure in the receiver to 300 bar, the low pressure switch is turned on, supplying gas from the cylinders to both the suction of the high-pressure cylinder and the receiver. At the same time, one part of the gas with a flow rate of 200 nm ³ / h is consumed by the HPC, and the other with a flow equal to the difference in the capacities of the low-pressure and high-pressure filters, fills the receiver to the set pressure (350 bar).

The receiver filling time is determined by the formula

The operating time of the HPC for one described cycle is 5 + 3.1 = 8.1 minutes, and the HPV is only 3.1 minutes. This means that in the process of increasing the pressure in the container of industrial gas thermostats with a large working volume, consisting of many mini-cycles considered and lasting several hours, KND does not work for 40% of the time this operation is performed, reducing energy consumption.

Cylinders manufactured by the industry with the appropriate working pressure and volume close to the value calculated by the formula (5) are used as receivers. In this case, the receiver can be a nitrogen cylinder 400-40 GOST 12247-80 with a volume of 400 liters (0.4 m ³ ) and a working pressure of 40 MPa (400 bar).

Claims (2)

1. A method for controlling a gas drive of a gas thermostat, comprising supplying gas to a pressure regulator installed on the suction pipe of a gas drive of a gas thermostat connecting a high pressure compressor and a low pressure compressor, equipping the high pressure compressor with shut-off valves and a gas unloading cylinder, equipping a low-pressure compressor with shut-off valves with gas unloading cylinder, characterized in that a receiver equipped with a pressure sensor and a shut-off valve is used as a pressure regulator , during the pressure rise in the gas thermostat container in the suction pipe of the high-pressure compressor, a pressure is maintained equal to or close to the maximum suction pressure of the high-pressure compressor, while when the pressure drops by 5 MPa, the pressure in the suction pipe of the high-pressure compressor includes low-pressure compressor that feeds gas simultaneously to the suction of the high-pressure compressor and to the receiver, and when the pressure rises in the receiver and the suction m pipeline of a high-pressure compressor to the maximum suction pressure, the low-pressure compressor is stopped by the signal from the receiver's pressure sensor. 2. A device for controlling a gas drive of a gas thermostat, comprising a pressure regulator mounted on a suction pipe connecting a high pressure compressor and a low pressure compressor interacting with each other, characterized in that the pressure regulator is made in the form of a gas receiver equipped with a pressure sensor and a shutoff valve.

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