RU2309322C2 - Method for reducing pressure of natural gas - Google Patents

Abstract

FIELD: process for reducing pressure of natural gas.

SUBSTANCE: method for reducing pressure of natural gas at gas distribution object involves using effect of integral heating of low-pressure gas by preliminarily energy dividing part of flow of reducible gas in vortex tube into hot flow and cold flow; supplying heat of outside source to generated low-temperature component of gas flow and mixing before delivery into consumer's low-pressure network, with water crystallization heat released during freezing thereof being used as outside source; melting ice resulted from said waste heat exchanging process after removal of unfrozen water remains in order to produce thaw water as independent commercial product; for producing the latter, using part of heat of low-pressure hot gas flow, generated with the use of vortex tube; discharging said flow into consumer's low-pressure network after heat-exchange with ice under melting process.

EFFECT: increased efficiency by utilizing refrigerating capacity of low-temperature gas flow component.

1 dwg

Description

The invention relates to a technology for reducing natural gas at gas-reducing facilities: gas distribution stations (GDS) of gas pipelines (MG) and gas distribution points (GRP) of a gas distribution system.

In order to exclude the supply to the gas pipeline of low pressure gas with a temperature of less than 0 ° C, a reduction method is proposed and used, based on the heating of high pressure gas before it is supplied to the pressure regulators of a gas-reducing object. High pressure gas is heated due to the regenerative utilization of heat of gaseous products of combustion of part of the natural gas subjected to throttling [1].

The main disadvantage of this method is the high level of operating costs during its implementation, due to the irreversible losses of natural gas associated with its combustion.

A known method of reduction, based on the effect of integrated heating of low-pressure gas, eliminating the consumption of part of the reduced medium for combustion, adopted during development as a prototype method [2].

Its essence is the purposeful use of the energy potential of compressed gas and the warmth of the environment.

In particular, to enable stable accumulation of environmental heat by a low-pressure gas stream, even in winter conditions, part of the reduced gas in the prototype method is subjected to energy separation in a vortex tube into hot and low-temperature flows. In this case, a vortex tube operation mode is selected such that the temperature of the low-temperature flow is guaranteed to be lower than the ambient temperature. This provides the condition for the selection of environmental heat by a cold gas stream. As a result of the subsequent mixing of the hot and heat-accumulated ambient cold flows, it is possible to increase the temperature of the low-pressure gas to the required values after the gas-reducing object.

With the technological simplicity of implementation, the disadvantages of the prototype method are the irreversible losses of the potentially cold storage capacity of the low-temperature component of the low-pressure gas stream that can be used, as well as the cumbersomeness and metal consumption of the heat exchange equipment to ensure the conditions of heat exchange between the gas and the surrounding atmosphere.

The aim of the present invention is to solve the problem of isothermal gas reduction through the use of a commercially viable technology for utilization of the refrigerating capacity of the low-temperature component of the low-pressure gas stream, as well as reducing the overall dimensions of the equipment used for heat recovery.

This goal is achieved by the fact that in the proposed method, the low-temperature component of the low-pressure gas stream after the vortex tube is heated by selecting the heat of crystallization of the water frozen at a given rate in a pair of heat exchangers alternately introduced and taken out of operation. At the same time, at the end of the freezing process, part of the unfrozen liquid is drained from the apparatus. The ice obtained by the described technology with minimal external energy consumption, as well as the water formed during its melting, is considered as an independent competitive product, covering both the operating costs of the gas-reducing facility itself and capital investment in creating a specialized cold utilization system for low natural gas flow pressure.

In addition, the use of freezing water as a source of thermal energy due to the heat transfer coefficient higher than that of air in the prototype method provides the possibility of reducing, at least 30%, the required heat transfer surfaces. With identical volumes of heat transfer, this is accompanied by a general decrease in the overall dimensions used to solve the target of technological devices.

Schematic diagram of the organization of the process of natural gas reduction at the gas reduction station (point) by the proposed method is shown in the drawing.

When implementing the proposed method, as in the prototype method, the high-pressure gas in front of the gas-reducing object is divided into two separate streams. The first of them (the smallest part) goes to the pressure regulators of the gas-reducing object, and the second (most) goes to the vortex tube 1. The cold low-pressure gas stream generated by the vortex tube 1, having a temperature of less than 0 ° C, is sent to one or several thermostatic cavity sequentially (parallel, parallel-sequentially) installed one after the other heat exchangers, initially filled with water and together forming one (several) technological threads. The diagram conventionally shows only a pair of heat exchangers of two technological threads. After passing through one of the devices 2, the cold low-pressure gas stream heated by heat exchange with frozen water combines with the hot gas stream coming from the vortex tube and enters the low-pressure network of the gas consumer. In parallel with this, from the decommissioned apparatus 2, through the pipeline 3 specially provided for this case, the remnants of unfrozen water are drained and the resulting ice mass is removed for subsequent cutting and packing. Then, according to the functional purpose, the devices change places.

In the case of a decision to release as the final commercial product water obtained by melting ice, after the completion of the draining operation from the apparatus 2 of unfrozen water, part of the hot low-pressure gas stream is fed into its thermostatic cavity. At the same time, technological pipelines and fittings are used, shown in the diagram with dash-dotted lines. The exhaust gas stream is discharged to the low-pressure gas consumer line, and the water generated as the ice melts from the apparatus is evacuated for subsequent sale.

Information sources

1. Ionin A.A. Gas supply. Textbook for high schools. - M .: Stroyizdat, 1981.

2. RF patent No. 2180420.

Claims (1)

A method of reducing natural gas pressure at a gas distribution facility based on the effect of integrated low-pressure gas heating due to preliminary energy separation of a portion of the reduced gas stream in the vortex tube into hot and cold flows, supplying the generated low-temperature component of the heat gas stream from an external source and then mixing them before delivery to the consumer network of low pressure, characterized in that the heat of crista is used as an external heat source water freezing during its freezing, and the ice obtained as a result of such recuperative heat transfer, after removing the remains of unfrozen water, is melted to produce melt water as an independent commodity product, while part of the heat of the low-pressure hot gas stream generated by the vortex tube is used to produce it after heat exchange with defrosted ice is discharged into the consumer network of low pressure.