During the epidemic situation, how much gas has been emitted by low temperature pressure vessels in gas industry?

2020.03.03

The sudden outbreak of the epidemic has completely disrupted the operation plans of enterprises in the upper, middle and lower reaches of the gas industry, involving production, storage, scheduling, distribution and other links, which have been seriously affected. Due to the extension of the Spring Festival holiday, the impact continues to worsen. According to the research data of economist Ren Zping's team, the film industry lost 7 billion yuan, the catering industry lost 500 billion yuan and the tourism industry lost 500 billion yuan during the seven days of the Spring Festival alone. The direct economic losses of these three industries alone exceeded 1 trillion yuan. As an important basic raw material of modern industry, gas products are regarded as the "blood" of industry. How many billions of losses are caused by gas industry?
How much each enterprise loses, the person in charge of the enterprise can effectively know the production cost, period expense, such as plant cost loss, management cost loss, personnel cost loss, and so on through directly accounting, but these are visible figures. the liquid medium in the low-temperature pressure vessel (the ISO tank, storage tank, road tanker, Micro Bulk, Dewar etc.), the gas discharged and lost due to the pressure rise of the relief valve, and whether the loss process can be predicted, deployed and reduced? Does each person in charge have detailed data that can be checked and documented?
As is known to all, the low temperature pressure vessels are used for cryogenic liquid (liquefied natural gas, liquid nitrogen, liquid oxygen, liquid argon, liquid hydrogen and liquid helium and other liquid) transportation and storage. If use rate is low or stop using of low temperature pressure vessel with liquid medium, after a long period of time (the length of time is directly related to the adiabaticity of the vessel), the liquid gasification increases the pressure and causes the relief valve to take off and exhaust the pressure. When the discharge of the safety valve cannot adapt to the pressure increase inside the container, when the pressure rises to the bursting pressure of the liner bursting disc, the liner bursting disc will open, which will cause safety hazards to a certain extent.
Because in the past enterprise operation process, the low temperature pressure vessels use persistently, the shutdown vacation is short, this kind of phenomenon is not highlighted seriously, but during the outbreak, companies’ low temperature pressure vessel utilization rate is extremely low, and because the outbreak shutdown time is long, this pressure is too high resulting in the loss of pressure relief. The safety hazard caused by continuous high pressure of containers is particularly obvious. So what can be done to improve the mess of gas loss after the epidemic? It is also the key point of careful calculation in gas industry.
In 2016, a company in Changzhou installed and used the digital display product which is developed and produced by DeleeTech, which can monitor the liquid level and pressure of Dewar through the remote mobile phone APP. During the epidemic period, the on-site inspection was avoided and the risk of virus infection was effectively reduced.

Head of the company can effectively and remotely control Dewar liquid level and pressure loss, can account for the loss caused by pressure relief and exhaust of Dewar during shutdown and confirm whether Dewar are within the safe pressure range to To ensure the safety of the low temperature pressure vessel during the lockout, to establish a basis for the later period of timely resumption of work;

The person in charge of the company also showed the data page of the monitoring process of a liquid argon Dewar during the shutdown of the epidemic situation from January 21 to February 13, and presented the data status of the change process of the liquid level and pressure of dewar bottle in detail.
Through the analysis of the process data in the figure above, it can be seen that:
1. On January 21, the liquid level is 65.8%, quality is 160.68kg. On February 13rd. When they resume work, liquid level is 17%, quality is 41.51kg. During the epidemic shutdown period liquid argon lost 48.8%, namely 119.17kg.
2. The liquid level curve shows a regular step-down, indicating that the drop is caused by the periodic blow-off of the safety valve for exhaust and pressure relief.
3. The regular serration type fluctuation of the pressure curve is consistent with the regular step-down of the liquid level curve. It indicates the periodic state of pressure relief after pressure rise and pressure rise again after pressure relief. The low pressure point is 1.93MPa, and the high pressure point is 2.36MPa, and it conforms to the limit value of 2.4mpa blow-off of the Dewar safety valve.

The process data in the figure above can be analyzed
1. The liquid level curve showed a regular step-down, and the cycle time of the two adjacent peaks of the whole curve was nearly 23 hours on average
2. The pressure curve shows regular sawtooth fluctuation, and the cycle time of the two adjacent peaks of the whole curve was nearly 23 hours on average.
3. According to the process data, the change of liquid level and pressure is consistent, and the cycle is nearly 23 hours. Periodically, the Dewar pressure rises to the blow-off pressure of the safety valve to relieve pressure and exhaust.
This is just the wear and tear process data of one liquid argon Dewar during the epidemic shutdown. Process data can help enterprises understand processes. Through analyzing the process data, provide data support for enterprise planning. Throughout the country tens of thousands of ISO tanks, storage tanks, road tankers, Micro Bulk
, Dewar and other low-temperature pressure vessels, the economic loss caused by the wear and tear is more than hundreds of millions, billions of dollars, tens of billions!
The person in charge of the company also disclosed that the remote mobile phone APP monitors the digital display product of Dewar liquid level and pressure, and also has the function of alarm of high and low liquid level, which can timely check the liquid level status and facilitate the coordination of distribution, scheduling and operation, so as to avoid unnecessary economic losses caused by contract disputes between supply and demand of gas. With the alarm function of high and low pressure, it can check whether the pressure state is within the safe pressure range in time. When the pressure value is higher than the limit value of safety valve in special circumstances, it can relieve pressure and exhaust gas artificially, so as to ensure the safe operation of production to the maximum extent. This product not only effectively monitored the company's low-temperature pressure vessels during the shutdown of the epidemic situation, but also continuously provided process data to facilitate the normal operation process after the resumption of work.