TW201022104A - System and method for real-time monitoring heating value of LNG in storage tank - Google Patents

Abstract

Disclosed are a system and a method for monitoring a heating value of liquefied natural gas (LNG) in a storage tank in real time. As a conventional LNG storage method separately storing the LNG according to heating values is changed to a combined storage method, it is required to calculate and monitor heating values of LNG in respective storage tanks. The real-time heating value monitoring system includes at least one LNG storage unit, a measuring unit provided to the LNG storage unit to measure density and temperature of the LNG, a calculation unit calculating the heating value using the density and temperature measured by the measurement unit, and a monitoring unit displaying the heating value calculated by the calculation unit.

Description

I 201022104 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a thermal value real-time monitoring system for a storage tank liquefied natural gas and a method thereof, and the system provides an instant monitoring system for the calorific value of the storage tank liquefied natural gas And the method thereof, the calorific value of the liquefied natural gas stored in the storage tank can be measured. 'Because of increasing the calorific value of the liquefied natural gas, the conventional method of combining the liquefaction and the liquefaction according to the calorific value is combined with the liquefaction of the county. The natural _ storage method to store liquefied woven fabrics, liquefied days can provide the ideal calorific value according to the supplier. [Prior Art] Generally, according to the use of liquefied natural gas, the natuml gas, LNG) storage is classified according to the high, medium and low calorific value of the liquefied woven fabric. Thus, 'liquefied natural gas can be stored separately. However, according to the new contract and the calorific value of spotcargo liquefied natural gas, the calorific value of liquefied natural gas in recent years ranges from the previous 9700 kcal/standard to the atmospheric volume (kcal/Nm3). Up to 10750kcal/Nm3, greatly increased to 1〇45〇kca]/Nm3 to 10750 kcal/Nm3. When the proportion of low calorific value LNG is relatively low, LNG is based on high, medium and low calorific value and is stored separately by sorting LNG storage tanks. Since the low calorific value of liquefied natural gas has increased sharply since the second year of the second year of the year, however, there has been a problem in the liquefied natural gas storage tank, especially in the case of low calorific value liquefied natural gas, if the liquefied natural gas is stored according to the calorific value, liquefaction Natural 201022104 • Gas will be lacking. To this end, in order to solve this problem, the LNG storage method has changed from a common separation method to a combined storage method. When the liquefied natural gas is stored in a liquefied natural gas storage tank based on the difference in high, medium and low calorific value, it is extremely difficult to judge the calorific value of each storage tank by a current measurement system. Therefore, it will lead to two main problems. First, it is difficult to control the calorific value of the gas in the storage tank. The second liquefied petroleum gas (LpG) calorific value control device is designed to increase the gas value with the smallest test according to the heat value of the contract or gas below the heating value of an object. In the sister-in-law (4) gas-touch control equipment, it is difficult to minimize the amount of liquefied petroleum gas. In summary, the liquefied natural gas that consumers expect is provided by the calorific value, so the calorific value of the liquefied natural gas storage tank must be monitored and managed effectively. φ [ SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a storage tank of a liquefied natural gas (LNG) using a storage tank provided by a standard temperature density (LTD). Monitoring system and its method. Another object of the present invention is to provide a calorific value instant control system for a storage tank liquefied natural gas and a method thereof, which provide a desired calorific value by a fixed calorific value or by paving, for example, a common separation of liquefied natural gas. The storage method is changed to a method of combining the liquefied natural gas. 201022104 In accordance with the present invention, the above and other objects are achieved by providing a touch that instantly monitors a liquefied seam in a storage tank. The hair growth system comprises at least: - a liquefied woven storage unit, a quantity of alcohol elements, a liquefied city gas storage unit for measuring the density and temperature of the liquefaction reduction, a calculation unit, a density and a temperature measured by the measurement unit To calculate the age, and the - monitoring unit, the calculated calorific value is calculated.

The thermal value real-time monitoring system of the storage tank liquefied natural gas disclosed in the present invention further comprises a layer-generating contact unit, and the dense sound and the field measured by the quantity zero element are used to judge whether the indicator layer is generated in the liquefied Tencel. The storage unit is wide and / according to the storage _ disclosure of the storage of Wei Huayun's calorific value of the real-time monitoring system also includes a - tree / dorm relay unit, transmitted by the measurement unit to determine the density of the unit Temperature value. According to another aspect of the present invention, there is provided a monitoring method for instantly monitoring a storage tank _ liquefied thief touch, the hair styling method includes the following steps: - measuring step, measuring stored in at least - liquefied natural gas storage The density and temperature of one of the units, the calculation step, the density and temperature values obtained from the remaining amount, calculate the calorific value, the shape-monitoring step, and the calorific value of the stored liquid is stored, and the calorific value is calculated. Obtained in the steps. * The thermal value monitoring system and method thereof for storing liquefied natural gas in a storage tank according to the present invention further includes a layer-forming step, and the density and temperature judgment and indication obtained from the layer are generated in the liquefied natural gas storage unit. Also, 6 201022104 According to the present bribe secret storage tank, the liquefied natural gas instantaneous value monitoring system and the method thereof further include a transmission step for transmitting the measured density through the wired/wireless communication relay unit. With temperature. The calorific value is calculated by a correlation equation:

Hv = 8464.34 - 20.1413*LD + 〇.〇538661.LD2.134.488N2, where ❷ HV : calorific value (kilometer/m3 of cubic meter volume)_编)(_heat value reference temperature: 15 degrees , about volume reference temperature: twist 1.01325 bar) LD: density of liquefied natural gas (kg / cubic meter chest (10)) at negative (10) degrees N2. nitrogen content (% of moles) (m〇] [%) then 'nitrogen The content is not more than 0.5%. [Embodiment] The current monitoring system and the f method of Weihua Tianqian Zhongzhi, which is the age of the listener, are described in detail below, and please refer to the diagram for explanation. "1st W" is a schematic diagram of a thermal value real-time monitoring system for storage tank ages according to the present invention. FIG. 2 is a schematic diagram of a monitoring screen of a calorific value instant & control system according to the present invention. "Fig. 3" is a step-by-step diagram of the thermal value of the liquefied natural gas according to the present invention; and "Fig. 4" is the operation of the instantaneous monitoring method of the calorific value of the liquefied natural gas in accordance with the present invention. Flow chart. 201022104 Before describing the invention, it should be noted that, by convention, liquefied natural gas is stored according to calorific value. The system is that the liquefied natural money is introduced from the same origin with almost the same calorific value, the calorific value is checked by the origin, and the liquefied natural secret heat value is stored in each of the storage tanks. That is to say, ^ points become high, medium and low calorific value. Recently, the range of the calorific value of the liquefied gas in #5| is increased, and the secluded age _(4) will be lacking. The storage system is converted into a combined storage method by the calorific value _ _ Tian Tian The calorific value stores all LNG together. In the past, because the calorific value of the introduction of LNG is a relative constant, and some natural liquefied gases have a particularly high or low calorific value, they will be stored separately, so there is no need for special (10) days of silk surface thief age. The calorific value of _. ❿ Also, when the quantity of LNG origin is limited, sometimes the label of origin is attached to the storage tank, for example, "Tokyo LNG, Japan, and, therefore, = the secret of the storage tank (4) calorific value is not It is necessary to measure the calorific value to identify 0#. However, in recent years, the origin and range of calorific value have been increased violently, and f is seen to store liquefied days according to calorific value, thus leading to liquefaction days _ There is a lack of storage tanks. Therefore, the miscellaneous touches are high, the towels are mixed, and the liquefied scorpions must be stored all together. In addition, in order to understand the value of the combined storage of liquefied natural gas, and thus provide the ideal tester, the feed reducer is provided. In addition, after the inspection, the liquefied natural gas storage basic control room must monitor the thermal value information detected by the respective LNG storage tanks. To this end, the present invention proposes the above. The point of view is considered and will be explained in detail as follows. First of all, please refer to the "Drawing Chart" to "3rd Map". The monitoring system of the riding and uncovering system is equipped with instant monitoring - storage tank _ liquefaction days The gas-heat value includes at least a liquefied natural gas storage unit 100, a density and temperature measuring unit 2, a liquefied natural gas storage unit 1 〇〇 measuring the density and temperature of the liquefied natural gas, and a layer generating unit 'Measure the drum and temperature to determine whether the layer is formed in the LNG storage unit, and indicate the result, the density and temperature measured by a calculation unit 400, _ unit to calculate the calorific value of the liquefied natural gas, And - the monitoring unit 5 (10), which displays the calorific value calculated by the computing unit 400. ❹ In addition, a wired/wireless communication relay unit 3 is provided to transmit the density and temperature values generated by the measurement unit to the layer generation determination unit 2〇〇 and the calculation unit. In order to calculate the calorific value of the liquefied natural gas in the liquefied natural gas storage unit 100, first, it is necessary to use a standard temperature density (4) set in the liquefied natural gas storage unit 100, such as 仃 仃 ' to measure storage in the liquefied natural gas storage unit. The density and temperature of LNG within 100. In fact, the standard temperature density is provided to check the temperature and density based on the height of the liquefied natural gas stored in the 201022104 liquefied natural gas storage unit 100, and thereby determine whether any layer is produced between liquefied natural gas having different properties. The standard temperature density scans the average of the height and the agronomy of each liquefied natural gas storage unit 1 hour, which takes an average of one hour. Standard temperature density measurements were performed twice a day. The standard temperature density is measured in a standby mode at a lower portion of the liquefied natural gas storage unit 100, that is, when not scanned, the standard temperature density is measured instantaneously. ❹ 曰 The measured temperature and density values are transmitted to the layer generation communication unit through the communication relay unit 300, and the calculation unit 400. The calculated material 400 transmits information on temperature and density to calculate the calorific value of the liquefied natural gas. The calculated calorific value is displayed immediately through the monitoring unit 5 of the liquefied natural gas storage basic control room. At this time, the layer produces a judgment sheet S, a judgment and a finger*, and whether the layer is formed in the stored liquefied natural gas in the liquefied natural gas storage unit. Here, the standard temperature density ❹ scan·natural gas bribe unit should be at the highest part of the highest part _temperature and density' to determine whether the layer is produced between different liquefied natural gas. When a layer is formed, this layer must be removed because it causes an error in the calorific value measurement of the LNG and causes an inversion. If the layer is produced, the layer must be removed in order to obtain a representative calorific value of all the liquefied natural gas in the liquefied natural gas storage unit 100 from the mosquitoes and temperatures of the Tencel. More specifically, in the standard temperature secret _ quantity, the temperature difference or density difference between the highest part 201022104 and the lowest part is used to determine that the layer is generated in the stored liquefied natural gas just inside the liquefied natural gas storage unit. When no layer is produced, there is only a small difference in temperature or density between the highest and lowest parts... In general, the temperature between the highest and lowest parts is no more than 〇3 degrees, and the difference in density is approximately 0.3 kg / cubic meter _3). When the layer is produced * On the other hand, the temperature difference becomes i degrees Celsius or higher, and the density also changes to the layer. Using such a discussion, it can be judged whether or not the layer is produced in the liquefied natural gas in the liquefied natural gas storage unit. Regardless of whether the layer is produced in each LNG storage unit, it is displayed by monitor monitoring or sound of the LNG storage basic control room. The recommended density difference between the highest and lowest parts of the LNG is about 1 kg/m3. Ο

"•Ο-Γοη IV -158.7^0 -158.6ec -158.5ec **158.5*C -158.S»C -158.1 ΛΓ -157.1 °C -1S7.1eC -1S7.1 *C -157.1 ·0

υ <<Liquefied natural gas without layer><Liquefied natural gas has layer> As explained above 'When no layer is produced' The temperature of the entire height of the liquefied natural gas 11 201022104 • The density system is almost no (four). Therefore, by measuring the temperature and density at any location, the representative thermal layer can be correctly calculated. However, in the present embodiment, the layer is formed in the liquefied natural gas storage unit 100, and the density and temperature vary depending on the height. @本, The calorific value obtained in the standard temperature density scan or pre-prepared mode cannot be regarded as the representative calorific value of the LNG storage unit excitation. For this, it is necessary to check whether a layer is produced. If so, in order to correctly calculate the calorific value, the layer needs to be removed. The storage method of the liquefied thief is converted from the various methods of storage as seen in the combined storage method to the occurrence of the layer in the liquefied natural gas. Therefore, the standard temperature density must be used to measure the density and temperature within the LNG storage unit 100. In addition, correlation equations are necessary for the calculation of the calorific value. As is generally known, 'the calorific value of natural gas is not blunt (inertga Ke said that there is only one reference ❹ density function (or special gravity function). If this principle should also be liquefaction _ 'different liquefaction The calorific value of the natural gas storage unit (10) can be calculated by measuring the temperature and density by standard temperature density. 〃 In order to evaluate the calorific value, the density is measured only by the standard temperature density. First, because of each liquefied natural gas storage unit UK) _2) The content is unknown, so the gas content in the liquefied natural gas should be lower than a predetermined level. Referring to the basic composition of the products of Korea Gas Co., Ltd. for loading and unloading LNG, liquefied natural gas contains an average of 〇·〇〇莫尔_%) of carbon dioxide and 〇2% of coffee and 1% of nitrogen. 12 201022104 Although, depending on the country of origin, the nitrogen content can actually exceed 1 mol%, this case is extremely rare. Since most of the nitrogen vaporizes in the form of boil-off gas BOG during navigation, the nitrogen content is actually maintained below 0.5 mol% when loaded and unloaded at the receiving end of the LNG. The bitterness is that LNG is composed of 99 mol/decane (CH4) and im〇i〇/0 nitrogen. The ratio of methane to nitrogen in the volatile gas is about 79 to 21 ‘that is, the nitrogen content is very high. Therefore, the nitrogen content of the liquefied natural gas will decrease in a short period of time. From the above, it can be seen that the error calorific value caused by the inert gas is estimated to be about 6%.6%. Assuming a gas content of 〇15 mol% in liquefied natural gas, using the density heat value correlation equation can reduce the estimated error by approximately 0.4%. In most cases* when the nitrogen content is 0 l5m〇l%, the error in calorific value is only about 0.2%. The following is a correlation equation obtained by regression analysis of the relationship between density, and the data obtained from the nitrogen content and the calorific value of the liquefied natural A is not apparent - and will be described later. The data for most of the gas in this area is the amount of LNG loaded and unloaded by Korea Gas Co., Ltd. except for LNG in Alaska. Although not derived from standard temperature density, this data contains nitrogen capacity, which can be substantially reduced due to the use of a fixed nitrogen capacity. Please refer to the table below. When the nitrogen content data is carefully considered, the curve fit of the relevant equation (C_f on g) is not more than 〇 6%. Conversely, 13 201022104 When the nitrogen content is not considered, the error may increase to 0 29%. In general, the nitrogen content is from 〇 to 0.3%. Setting the nitrogen content to 0.15% in order to reduce the calorific value error results in an unknown nitrogen content, which is understood to mean that the largest error including an error can be reduced to 〇 21% by regression analysis. Therefore, the calorific value is calculated using the measured density value and is calculated by the following correlation equation:

Hv = 8464.34 - 20.1413 'LD + 0.0538661 'LD2 - 134 488N2, where

Hv: calorific value (kcal/m3 of kcal/standard atmospheric pressure) (kCal/Nm3) (for calorific value reference temperature: 15 degrees, for volume reference temperature: 1.01325 bar) LD. LNG (kg/ The density of cubic meters is minus 6 〇 N2 : nitrogen content (% of moles) (m 〇 1%) 〇 At this time, the 'nitrogen content is less than 0.5%, more preferably 0.15%. The calorific value is calculated from the correlation equation, and the exact equation related to the density and the calorific value of the liquefied natural gas is indispensable. The density from the seven places and the calorific value of the LNG are analyzed to confirm whether the above correlation is It is feasible. Therefore, it is confirmed that the density and calorific value are highly correlated. For example, the regression analysis shows that the error rate is about 0.06% through the result of the second equation. Regression analysis of the relationship between LNG density and calorific value The organization with 201022104 is listed in the table below.

Data of regression analysie of relations between density and heating value of LNG

Place of origin LNQ density @-160 (Kg/n^3) Nicontent (mol%) Heating value (kcaUNrrfZ) Hewing value obtained through regression analysis N2 contained error (%) N2 = 0% error (%) N2=0.1% error (%) Alaska 421098 0,13 951744 9517.12 0,00 9534.13 0.18 9521.00 0.04 Egypt 430.192 0.016 9767.9 9766.30 -0.02 9768.34 0.00 97K.21 -0.13 Yemen 442909 0.06 10096.37 10102.33 006 10110:54 0.14 10097.41 0,01 sp^s6l-i (sample from Pyeongtaek) 457.282 0.022 10520.7 1051490 -0,06 10517.92 -0.03 105W;79 -0.15 Average Contents of Kogas In ao〇4 459,215 0,19 10549.72 10548.80 -0.01 1057438 0.23 1056125 0,11 Oman 466.483 0.239 10759.26 10758.23 -0.01 10790.20 0.29 10777,07 0.17 Australia 468:404 0.07 10835.25 10839.01 0.03 10848; 17 0.12 10835.04 0.00 _ The reference condition for liquefied natural gas is the correlation between the density and calorific value of the liquefied natural gas. 'Here, the reference temperature is set at minus At 160 degrees, the pressure faced is not considered because it has little effect on the density of LNG. The display of the display value of the indoor computer via the LNG storage base is displayed by the calculation of the calorific value calculated by the calculation unit 400, as shown in Fig. 1. "Figure 2" is an example of the results displayed. At the same time, as shown in Figure 1, Figure 2 and Figure 4, the method of monitoring the calorific value of liquefied natural gas in the LNG storage unit 100 is included, including the measurement of the LNG storage unit. The step of density and temperature of the LNG in the sputum, using the measured density and temperature values (S300) to determine and indicate whether a layer is produced in the liquefied natural gas storage unit, using the measured density and temperature (S400) The calorific value, and the calorific value calculated in the calculation step (S5〇〇). Further, a transmission step (S2 〇 0) may be included. In the transmission step (S2 〇〇), the density and temperature values obtained at the measurement step (S100) may be transmitted through the wired/wireless communication relay unit 300. 15 201022104 In addition, the layer generation determining step (S300) uses the density and temperature value transmitted through the communication relay unit 300 to determine whether or not a layer is generated. If a layer is produced, the layer is removed and the representative calorific value of the LNG in the LNG storage unit (10) is then obtained via the calculation step (s4〇〇). From the LNG storage basic control room, it is possible to instantly monitor the calculated individual calorific values. For example, in the calculation step (10) 0), as described above, the density value and the temperature value are obtained and fined in the side equation, and the calorific value calculated by the computer monitor of the control room is calculated. Here, the correlation equation for determining the layer generation and the calorific value is a pre-designed computer program and stored in the layer generation judging unit 2, and the calculation unit 4A. The above-mentioned system operation process and method for monitoring the calorific value of liquefied natural gas in a LNG storage unit are described in "i" to "4". 〇 1) Instantly measure the temperature and density of LNG in each LNG storage unit using standard temperature densities. 2) The measured temperature and enthalpy value are transmitted to the layer generation judging unit 200, and the calculation unit 4A, through the track towel following the single 兀3GG. Here, when sweeping the cat, if the temperature difference between Celsius or higher or the density difference is i kg/m3 or more between the highest part and the lowest part of the LNG, the layer is judged to be generated and transmitted according to whether or not the layer is generated. Warning sounds or listening to the notification of liquefied natural money storage basic control room, or through computer monitoring to identify the display of LNG memory unit. 201022104 3) Remove the layer in the corresponding LNG storage unit. (Remove is focused). 4) After removing the layer, the temperature and density of the LNG storage unit 1 再次 will be measured again to confirm whether the layer has been removed. 5) The calorific value of LNG is calculated by calculation unit 4〇〇. 6) The final calorific value of the individual LNG residual units will be displayed in the monitor of the liquefied natural storage base control room and is monitored on-the-fly. In summary, according to the disclosed embodiment of the present invention, the supplier provides the liquefied natural gas according to the ideal calorific value, which is obtained by averaging the liquefied natural density and temperature in the root liquefied natural gas storage tank. The coefficient of the amount of correlation is used to identify the calorific value of the liquefied natural gas. Furthermore, because the calorific value information of each storage tank can be monitored by the control room at any time, the manpower for management needs is reduced, thereby improving work efficiency and achieving economic benefits. © 轴本发发日前前本行实施_Exhibition as above, but it is not intended to limit the invention, any familiar artisan ★ can make some changes to the face without departing from the spirit and scope of this month The patent of the present invention is defined by the patent application specification. [Simplified description of the diagram] The instant monitoring system for storing the calorific value of liquefied natural gas is shown in Fig. 1 as a schematic diagram of the structure of the storage tank of the present invention; Fig. 2 is a schematic diagram of the screen of the monitoring (4) of the _Hot value (4) monitoring secret; 17 201022104 Fig. 3 is a flow chart showing the steps of the instant heat monitoring of the liquefaction and the reduction of the liquefaction time; and Fig. 4 is a flow chart showing the steps of the liquefied natural gas in the storage tank of the present invention. The operation of the thermal value monitoring method [Main component symbol description]

100 LNG storage unit 200 Measurement unit 200' Layer generation judgment unit 300 Communication relay unit 400 Calculation unit 500 Monitoring unit S100 Measurement step S200 Transmission step S300 Judgment step S400 Calculation step S500 Monitoring step

Claims (1)

201022104 VII. Patent application scope: 1. A monitoring system for instantly monitoring the calorific value of a liquefied natural gas in a storage tank, the monitoring system comprising: at least one liquefied natural gas storage unit; a measuring unit providing the The liquefied natural gas storage unit measures the density and temperature of the liquefied natural gas; - the amount of the mosquito is measured by the measuring unit and the temperature is calculated by the measuring unit; and the calorific value obtained by the difference of 70 anglings . 2. The monitoring system as described in claim i of the patent scope further includes a layer generating judgment unit, and the density measured by the measuring unit and the temperature are used to determine whether the layer is generated in the liquefied natural gas storage. Within the unit. 3. If the supervision (4) system described in the second paragraph of the patent application includes a wired/non-infrared communication relay unit, the transmission is obtained by the measurement unit to the layer generation judgment unit and the calculation unit. This density is the same as this temperature value. 4. The monitoring system of claim i, wherein the calorific value is calculated by one of the following equations: Hv = 8464.34 - 20.1413*LD 134·488Ν2 'where the calorific value (kcal/standard-atmospheric fresh) Cubic meter volume (four) / m in calorific value reference temperature: 15 纟, on volume reference temperature · · 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 液 液 液 液 密度 密度 密度 密度 密度In the negative (10) degree, N2: nitrogen content (% of moles) (mol%) 5. The monitoring secret described in item 4 of the patent application, wherein the nitrogen content is not more than 0.5% (%). - a monitoring method for instantly monitoring the calorific value of a liquefied natural gas in a storage tank, the steps of the monitoring method comprising: a measuring step of measuring one of the liquefied natural gas stored in at least one liquefied natural gas storage unit Density and temperature; a calculation step of calculating the calorific value using the measured density and the temperature value; and controlling the calorific value of the LNG storage unit, and the calorific value is The meter 7. The method of monitoring according to item 6 of the patent application, further comprising a layer generating determining step, using the measured density and the temperature to determine whether the layer is generated in the liquefied natural gas storage unit. 8. The method of monitoring according to claim 7 further comprising a transmitting step of transmitting the measured density and the temperature through a wired/wireless communication relay unit in the measuring step. The method of monitoring according to item 6 of the patent scope 'where the calculation of the calorific value 201022104 is obtained by a correlation equation · 20.1413*LD + 0.0538661*LD2 - Hv = 8464.34 134.488Ν2, where HV • calorific value (kcal/ Volume of cubic meters (kcal/Nm) at atmospheric pressure (for calorific value reference temperature: u degrees, volume reference temperature: 1.01325 bar) LD. liquefied natural gas (kg/m3) (kg/m3 The density of the product is minus 160 degrees A: the content of nitrogen (% by mole) (m〇i%) 10. The method of monitoring according to claim 9 wherein the nitrogen content is not more than 0.5%.