RU2279019C2 - Liquefied gas cooling apparatus - Google Patents

Abstract

FIELD: cryogenic technique, plants for producing liquefied low temperature carbon dioxide.

SUBSTANCE: apparatus includes throttling valve, supply and withdrawing pipelines. Apparatus includes in addition filter with filtering and throttling functions arranged directly after throttling valve; system for automatic control of summed pressure drop in throttling valve and filter; pipelines for blowing filter, lock fitting. Filter is mounted on discharge pipeline with possibilities of disconnecting from it and connecting with blow pipelines.

EFFECT: enhanced purity of liquefied gas.

3 cl, 1 dwg

Description

The invention can be used in cryogenic technology, as well as in installations for the production of liquid low-temperature carbon dioxide in distilleries.

A known device for cooling liquefied gas (prototype) contains a throttle valve inlet and outlet pipelines [1]. Using this device, carbon dioxide, pre-compressed in the compressor to a pressure of 6.5-7.0 MPa and liquefied in a condenser at a temperature of 26-29 ° C, is throttled to 0.8-1.2 MPa. In this case, part of the liquid evaporates, due to which the resulting vapor-liquid mixture is cooled to -46-35 ° C [2].

Typically, liquefied gases contain dissolved impurities, which upon cooling of the liquid pass into a finely dispersed crystalline state. In particular, liquefied carbon dioxide obtained from alcoholic fermentation gases contains water and organic substances. The presence of impurity crystals in the chilled product reduces its quality and the reliability of the installation [1]. The described device does not allow to clean the cooled liquefied gas from these impurities.

The objective of the invention is to increase the purity of liquefied gas.

The solution to this problem is achieved by the fact that the device for cooling liquefied gas containing a throttle valve, inlet and outlet pipes, according to the invention is equipped with a filter that performs the function of filtering and throttling, located directly behind the throttle valve, filter purge pipelines and valves, and the filter is mounted on outlet pipe with the ability to disconnect from it and connect to the purge pipelines. The device may have two filters connected in parallel, as well as a system for automatically controlling the total pressure drop across the throttle valve and a filter containing pressure sensors in the inlet and outlet pipes, a command unit and actuators for the valve and stop valves.

In this device, impurity crystals formed during throttling are delayed by a filter installed on the discharge pipe, and the filter simultaneously performs two functions - filtering and throttling. As impurities accumulate in the filter, its hydraulic resistance gradually increases, and therefore the pressure drop across the filter also increases. To ensure the stable operation of the entire installation, the total pressure drop across the throttle valve and filter must be kept constant. During a certain period, this is carried out by a corresponding change in the pressure drop across the butterfly valve by increasing the degree of its opening. After the throttle valve is fully open, the filter must be turned off and regenerated. To this end, the inventive device is equipped with purge pipelines and valves. Regeneration is carried out by purging the filter with heated gas, while the impurities accumulated in it are evaporated and removed. The continuity of the installation can be achieved using two filters connected in parallel and acting alternately: while one of them filters, the other undergoes regeneration. To control the operation of the device, it is advisable to use an automated system containing pressure sensors in the inlet and outlet pipes, a command unit and actuators of the throttle valve and stop valves.

The inventive device has the following significant advantages over the known.

1. When using the same filter and the same installation performance, the period of operation of the filter until the next regeneration in the inventive device is much longer, and the degree of purification of the product is higher.

2. Since in the inventive device the filter simultaneously performs two functions - cooling (due to the throttle effect in the filter itself) and cleaning the product, the energy consumption for overcoming the hydraulic resistance of the filter is not a loss.

The inventive device is shown in the drawing.

It contains a throttle valve 1, inlet and outlet pipelines 2 and 3, a filter 4, purge pipelines 5 and 6, shutoff valves 7-10, as well as a system for automatically controlling the total differential pressure across the throttle valve and filter, containing pressure sensors 11 and 12, command unit 13 and actuators of the valve and valves. Parallel to the filter 4 is connected to the second of the same filter.

The device operates as follows.

Liquefied gas with parameters p ₁ and T ₁ containing dissolved impurities is continuously supplied through line 2 to the throttle valve 1, where the pressure drops to p, the liquid boils and its temperature drops. In this case, part of the dissolved impurities crystallizes and the resulting three-phase mixture enters the filter 4. Due to the hydraulic resistance of the filter, the throttled flow parameters and the crystallization of impurities also decrease in it, and the crystals are retained in the pores of the filter, therefore, the vapor-liquid mixture discharged from the filter through the pipeline for 3 s the final parameters p ₂ and T ₂ does not contain a solid phase. Since the accumulation of crystals in the filter leads to an increase in its hydraulic resistance, the pressure drop across the filter increases Δp _f = p-p ₂ . To maintain during operation the setpoint temperature difference ΔT = T ₂ -T ₁ constant total pressure drop necessary to keep Δp = Δp _a + Δp _f = p ₁ -p _2, measured by sensors 11 and 12 that automatically ensures a decrease _{in the} differential pressure Ap = p ₁ -p on the throttle valve by increasing the degree of its opening.

Upon reaching the full opening of the throttle valve, the command unit 13 generates signals by which the valves 7 and 8 are closed, and the valves 9 and 10 on the purge pipelines open, at the same time, the reverse actions are performed with the fittings of another filter, as a result, filter 4 is turned off for regeneration, and the other filter already regenerated, is included in the work. In this case, the degree of opening of the throttle valve is also automatically reduced to its original value. The following operation cycle is repeated.

Information sources

1. Gerasimenko V.V. Carbon dioxide production in distilleries. -M. Food Industry, 1980, pp. 97-104, 20.

2. Altunin V.V. Thermophysical properties of carbon dioxide. - M. Publishing house of standards, 1975, p.303.

Claims (3)

1. A device for cooling liquefied gas containing a throttle valve, inlet and outlet pipes, characterized in that it is additionally equipped with a filter that performs the function of filtering and throttling, located directly behind the throttle valve, a system for automatically controlling the total pressure drop across the throttle valve and filter, filter purge pipelines and shutoff valves, moreover, the filter is installed on the discharge pipe with the possibility of disconnecting from it and connecting to purge pipelines. 2. The device according to claim 1, characterized in that it is equipped with two filters connected in parallel. 3. The device according to claim 1, characterized in that the automatic control system comprises pressure sensors in the inlet and outlet pipes, a command unit and actuators of the throttle valve and stop valves.