Water-sweeping, drying and inerting integrated process for natural gas transportation pipeline

Abstract

The invention relates to a water-sweeping, drying and inerting integrated process for a natural gas transportation pipeline. The water-sweeping, drying and inerting integrated process for the natural gas transportation pipeline comprises the following steps: putting a pipeline cleaner train into the natural gas transportation pipeline by virtue of a pipeline head-end ball launching barrel, wherein the pipeline cleaner train consists of a pipeline cleaner I, a freshwater section plug, a pipeline cleaner II, a water-based gel section plug, a pipeline cleaner III, a chemical drying agent section plug, a pipeline cleaner IV, a dry gas section plug and a pipeline cleaner V; injecting compressed and dried nitrogen gas into the natural gas transportation pipeline from a gas inlet pipeline to push the pipeline cleaner train to travel forwards in the natural gas transportation pipeline, and exhausting pressure test water from a pipeline tail-end ball receiving barrel and a water exhausting pipeline; and after the pipeline cleaner train reaches the pipeline tail end, sequentially taking out the pipeline cleaners from the pipeline tail-end ball receiving barrel, and exhausting freshwater, water-based gel, a chemical drying agent and dry gas from a water drainage pipeline. After passing balls once, the water-sweeping, drying and inerting integrated process can reach conditions of introducing natural gas and putting the introduced natural gas into production.

Description

technical field [0001] The invention relates to a construction process of a natural gas transmission pipeline, in particular to an integrated process of sweeping, drying and inerting of a natural gas transmission pipeline. Background technique [0002] After the hydrostatic test of the natural gas pipeline, it is necessary to carry out various processes such as water sweeping, drying, nitrogen filling and inerting. The main component of natural gas is methane (CH4). Under high pressure and low temperature, methane easily combines with water to form natural gas hydrate (CH4·H2O), commonly known as combustible ice, which blocks pipelines, flow meters, valves, etc., and affects the normal transportation of pipelines; Residual moisture is easy to combine with sulfur dioxide in natural gas to form acidic hydrogen sulfide solution to corrode the pipe wall; in addition, the residual free water in the pipeline accumulates in low-lying places, which can reduce the cross-sectional are...

AI Technical Summary

Problems solved by technology

For long-distance, large-diameter, deep-water subsea natural gas pipelines, water cleaning and drying are carried out separately. The pipeline needs to pass the ball multiple times, which takes a long time for construction and wastes a lot of resources such as equipment and fuel. In addition, with the increase in the number of ball passes, the pig The risk of wear, leakage and ball jamming is also greatly increased

Once the ball is stuck in the submarine pipeline, the cost will be very high if the ball has to be taken care of continuously

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