RU2651139C2 - Installation for receiving melt water obtained by utilization of the cold of liquefied natural gas - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: installation for obtaining melt water, the source of which is water ice obtained by utilization of the cold of liquefied natural gas, contains two pairs of successive heat exchangers with heat transfer surfaces, which are formed by a series of corrugated panels with channels for liquefied natural gas, water supply valves to heat exchangers, valves for supplying liquefied natural gas to the channels of heat transfer panels for freezing water and valves for supplying heating gas to the channels of the heat transfer panels to control the switching of the respective pair of heat exchangers from the ice-freezing mode to the melting mode.

EFFECT: use of this unit allows the use of part of the water to be cooled on the outer surface of the panels and then obtained from the heated ice melt water by cooling the panels by utilizing the cold of the liquefied gas.

1 cl, 1 dwg

Description

The invention relates to refrigeration and cryogenic technology and can be used for regasification of small volumes of liquefied natural gas (LNG).

The source of melt water is water ice, obtained by freezing part of the water in a heat exchanger cooled by a refrigerant.

An example of a plant for producing melt water may be a cylinder-shaped ice machine [1]. The main element of such an installation is a vertical shell-and-tube apparatus, in the annulus of which the refrigerant boils (or circulating cold brine). Part of the water entering the pipe space and moving through the pipes from top to bottom freezes and is deposited in the form of ice on the inner surface of the pipes, and the remaining non-frozen part flows into the pan and then into the water distribution device. Thus, hollow or continuous cylinders of ice are obtained in the tubes over the entire height of the tubes. At the end of the freezing process, ice is thawed and ice cylinders are removed from the tubes of the ice maker.

However, the disadvantage of this installation is that its operation requires a refrigeration unit that provides the necessary lowering of the temperature of the water entering the tube space of the freezer. In addition, the optimal thickness of cylindrical ice is only 4-6 mm.

Closest to the technical nature of the claimed installation is the installation in the form of a cryogenic ice gasification platform, designed to create an ice block or use to freeze water in soft soils [2].

This installation is made in the form of a cryogenic ice gasification platform, on which there is a cryogenic tank with liquid nitrogen, pipelines, a liquid nitrogen pump, heat exchange elements covered by a protective shell, an expander and a platform shield.

Liquid nitrogen is taken from the tank by a liquid pump and the nitrogen pressure rises to 1.5-2 MPa, and then nitrogen under pressure enters the heat exchange elements located in the inner space of the protective shells filled with water.

After regasification, gaseous nitrogen enters the expander, where it expands, the temperature of nitrogen decreases, and it is redirected to the heat exchange elements, from which it is released into the atmosphere after heating. The process of freezing water inside the protective shells continues until an ice monolith is obtained inside the shells, i.e. obtaining an ice support column.

A disadvantage of this installation is that its system uses a liquid cryogenic pump and an expander.

In addition, liquid nitrogen is a working cryoproduct. This makes it necessary to have either an air separation unit (ASU) for the production of liquid nitrogen, or to bring it from an enterprise receiving liquid nitrogen.

One of the possible types of refrigerant, which is proposed to be used in the method [3] for producing melt water, may be LNG.

The task to which the invention is directed is to develop a continuous operation unit, the operation of which will be based on utilization of the cold of liquefied natural gas during its regasification.

The technical result that can be obtained by using the claimed device is to use for cooling and freezing on the outer surface of the panels part of the water and then to obtain melt water from the melted ice by cooling the panels by utilizing the cold of liquefied natural gas.

The specified technical result is achieved by the fact that two pairs of series-connected heat exchanger-freezers with highly efficient heat-exchange surfaces in the form of corrugated panels, into the internal channels of which LNG is used, are used in the installation.

The achievement of this technical result is facilitated by the fact that in the installation for producing melt water containing two pairs of successively installed heat exchanger-freezers, LNG flows periodically through only one of the pairs, and in each of the heat exchanger-freezers after the formation of 0.3-0.5 from of the volume of water filled with ice, switching to the second pair of heat exchangers-freezers takes place, and the first one drains unfrozen water and they work in the heating mode, at which melt water is drained from them, obtained Naya from melted ice.

The installation for the production of melt water, shown in Fig. 1, includes pipelines 11 and 16 for introducing LNG into the installation and outputting the regasified LNG stream, valves 12 and 13 for supplying LNG to heat exchangers-freezers, heat exchangers-freezers 6-9 with heat transfer panels 10 in the internal volume, the valves 14 and 17 of the outlet from the heat exchangers-freezers of regasified LNG flows, valves 2-5 supplying water supplied through line 1 to the heat exchangers-freezers, valves 18, 19, 21 and 24 for draining unfrozen water from the heat exchangers 6- 9 on line 20, lines 22 and 32 of the heating gas stream at the inlet to and from the heat exchangers 6-9, with valves 23, 25, 15, 26, a line for draining melt water 29 with valves 27, 28, 30, 31.

Installation for producing melt water works as follows: on line 1 through open valves 2-5, water is supplied to the inner space of heat exchangers-freezers 6-9 between panels 10 located in each of the heat exchangers 6-9.

Then, through line 11, with the valve 13 closed, through the open valve 12, it is supplied to the inner space of the panels of the LNG heat exchanger 7, which boils in this heat exchanger, cooling the water in it and partially turning it into ice. The vapor of the vaporized LNG is then fed to the panels of the heat exchanger 9, ice freezing also occurs on the outer surface, and upon leaving the panels through the open valve 14 with the valve 15 closed, the line 16 is delivered to the natural gas consumer.

After freezing the required volume of water in heat exchangers-freezers 7 and 9, the LNG supply through valve 12 is stopped, it closes and the valve 13 for supplying LNG to heat exchangers 6 and 8 opens when valve 17 is open. Valves 18 and 21 open and when valves 19 and 24 are closed, line 20 is the discharge of unfrozen water.

The heat exchangers 6 and 8 begin to work in the water freezing mode, and a flow of heating gas is supplied to the freezing heat exchangers 7 and 9 through line 22, which, when valve 23 is open and valve 25 is closed, enters the interior of the panels and passes through the panels of heat exchangers 7 and 9 sequentially and through the open valve 15 is output via line 32. The valves 25 and 26 are closed.

As the heating gas flow passes through the inner space of the panels, the ice formed on the outer surface of the panels of the heat exchangers-freezers 7 and 9 is melted and the resulting melt water is discharged through valves 27 and 28 with the valves 30 and 31 closed and discharged from the unit through line 29.

Subsequently, the processes taking place in heat exchangers-freezers 6 and 8 are repeated similarly to the processes in heat exchangers-freezers 7 and 9, and the latter are filled with water intended for freezing.

Information sources

1. Kurylev ES, Gerasimov N.A. Refrigeration units. 3rd ed., Revised. and add. L .: Engineering, 1980 .-- S. 343-345.

2. Marinyuk B.T., Ivanov B.A., Dyachkov M.I. To the question of the use of cryogenic technology for freezing water and soft soils. In kN. Processes and devices of cryogenic technology and conditioning. - Interuniversity collection. scientific works. - L .: LTIHP, 1985 .-- S. 64.

3. RF patent No. 2315902, IPC F17C 9/02, publ. 04/27/2007.

Claims (1)

Installation for the production of melt water, the source of which is water ice obtained by utilizing the cold of liquefied natural gas, characterized by the presence of two pairs of heat exchangers installed in series with heat transfer surfaces formed by a series of corrugated panels with channels for liquefied natural gas, valves for supplying water to heat exchangers, valves supply of liquefied natural gas to the channels of heat transfer panels for freezing water and valves for supplying heating gas to the heat transfer channels giving panels for controlling the switching of the corresponding pair of heat exchangers with the ice freezing mode at its melting mode for melt water.

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