JP2023115930A - Method for determining whether or not atomized lpg adheres to inner wall surface of backflow piping of calorific value adjustment device - Google Patents

Abstract

To provide a method for determining whether or not atomized LPG adheres to an inner wall surface of piping on a downstream side of a calorific value adjustment device.SOLUTION: Provided is a method for determining whether or not atomized LPG adheres to an inner wall surface of downstream piping of a calorific value adjustment device 1 that adjusts a calorific value of NG by adding LPG from a liquid nozzle 13 to the NG flowing through a main flow pipe 3. The calorific value adjustment device comprises: an outer cylinder 5 that is provided in the main flow pipe 3 through which the NG flows, and receives the supply of the NG from a base end side to eject the NG toward a tip side; an inner cylinder 9 that is arranged coaxially with the outer cylinder 5 within the outer cylinder 5 and via a space with an inner wall of the outer cylinder, and receives the supply of the NG from a branch tube 7 branched from the main flow pipe 3; and a liquid nozzle 13 that is arranged coaxially with the inner cylinder 9 and discharges LPG into the inner cylinder 9. In the method, if Sm×t×(Psat,LPG-PLPG) is 1.5×1010 or more, it is determined that LPG does not adhere to the inner wall surface of piping, and if Sm×t×(Psat,LPG-PLPG) is less than 1.5×1010, it is determined that LPG adheres to the inner wall surface of the piping.SELECTED DRAWING: Figure 1

Description

本発明は、液化天然ガス（LNG）を気化させた天然ガス（NG）に液化石油ガス（LPG）を気化・混合することにより熱量調整する熱量調整装置の後流配管内壁面に、微粒化されたLPGが付着するか否かの判定方法に関する。 In the present invention, atomized liquefied natural gas (LNG) is vaporized and mixed with liquefied petroleum gas (LPG) to vaporize and mix liquefied natural gas (LNG) on the inner wall surface of the downstream pipe of the calorific value adjustment device that adjusts the calorific value. It relates to a method for determining whether or not LPG adheres.

都市ガスの熱量調整は液化天然ガス（LNG）を気化させた天然ガス（NG）に液化石油ガス（LPG）を気化・混合することにより行う。近年はシェールガスなどメタン成分の多いLNGの輸入が増加しており、LPGによる増熱幅が増加する傾向にある。 The calorific value of city gas is adjusted by vaporizing and mixing liquefied petroleum gas (LPG) with natural gas (NG) obtained by vaporizing liquefied natural gas (LNG). In recent years, imports of LNG, which contains a large amount of methane, such as shale gas, have increased, and the amount of heat gain by LPG tends to increase.

このような熱量調整方法としては、例えば特許文献１に開示された「流体微粒化ノズル装置」を用いて行うことができる。
特許文献１においては流体微粒化ノズル装置の実施形態として、NG（気体）にLPG（液体）を添加して都市ガスを製造する熱量調整装置が開示されている。 As such a heat amount adjustment method, for example, a "fluid atomization nozzle device" disclosed in Patent Document 1 can be used.
Patent Literature 1 discloses, as an embodiment of a fluid atomization nozzle device, a calorific value adjusting device for producing city gas by adding LPG (liquid) to NG (gas).

この熱量調整装置１は、図６に示すように、NGが流れる主流管３に設けられたベンチュリ管からなる外筒５と、主流管３から分岐した分岐管７と、外筒５内に配置されて分岐管７からNGの供給を受ける内筒９と、内筒９内に設けられて液体供給管１１からLPGの供給を受ける液体ノズル１３とを備え、主流管３を流れるNGに液体ノズル１３からLPGを添加することでNGの熱量を調整するものである。（特許文献１の段落［0042］参照）。 As shown in FIG. 6, the heat quantity adjusting device 1 is arranged in an outer cylinder 5 made of a venturi tube provided in the main pipe 3 through which NG flows, a branch pipe 7 branched from the main pipe 3, and the outer cylinder 5. and a liquid nozzle 13 provided in the inner cylinder 9 and receiving LPG supply from the liquid supply pipe 11 . By adding LPG from 13, the heat quantity of NG is adjusted. (See paragraph [0042] of Patent Document 1).

特開２０１２－２０６０７１号公報JP 2012-206071 A

特許文献１に開示された流体微粒化ノズル装置が組み込まれた熱量調整装置は、ベンチュリ管を水平に設置する、すなわち横置きすることが前提とされており、縦置きとした場合に正常に熱量調整が機能するかについては言及されていない。 The calorific value adjustment device incorporating the fluid atomization nozzle device disclosed in Patent Document 1 is premised on the venturi tube being installed horizontally, that is, placed horizontally. No mention is made of whether the adjustment works.

熱量調整装置の据付姿勢を縦置き（鉛直上向き又は鉛直下向き）とする場合、高さ方向に所定のスペースが必要となる。そこで、設備の高さをできるだけ抑えるため、熱量調整装置の後流に設ける直管部を短くしてエルボを設ける必要がある。 When the calorific value adjustment device is installed vertically (vertically upward or vertically downward), a predetermined space is required in the height direction. Therefore, in order to keep the height of the equipment as low as possible, it is necessary to shorten the straight pipe portion provided downstream of the heat quantity adjusting device and provide an elbow.

熱量調整後の製造ガス温度と製造ガスの露点の差（以下、「過熱度」という）が小さい条件においては、流体微粒化ノズル装置によって微粒化されたLPGの気化にある程度の距離を要する。そのため、その気化の最中に前記エルボによって生じる偏流の影響で微粒化されたLPGが熱量調整装置の後流側配管の内壁面に付着して気化が阻害され、想定外の低温となることが明らかになった。 Under conditions where the difference between the dew point of the production gas after heat quantity adjustment and the production gas (hereinafter referred to as "superheating degree") is small, vaporization of LPG atomized by the fluid atomization nozzle device requires a certain distance. Therefore, during the vaporization, the atomized LPG adheres to the inner wall surface of the downstream side pipe of the calorific value adjustment device due to the influence of the drift caused by the elbow, and the vaporization is hindered, resulting in an unexpectedly low temperature. It was revealed.

このような状態となると、熱量調整が正常に機能しないのみならず、想定外の低温による設備への悪影響が懸念される。
そのため、かかる事態が生ずるか否かを判定する定量的な判定基準が求められていた。 In such a state, not only does the calorie adjustment not function normally, but there is concern that the unexpectedly low temperature will adversely affect the equipment.
Therefore, there has been a demand for a quantitative judgment criterion for judging whether or not such a situation occurs.

本発明はかかる課題を解決するためになされたものであり、熱量調整装置の後流側において、微粒化されたLPGが後流配管内壁面に付着するか否かの判定方法を提供することを目的としている。 The present invention has been made to solve such problems, and provides a method for determining whether or not atomized LPG adheres to the inner wall surface of the downstream pipe on the downstream side of a calorific value adjusting device. purpose.

熱量調整装置の据付姿勢を縦置きとし、過熱度が小さく、かつ熱量調整装置後流にエルボを設置する場合について実証試験を実施し、微粒化されたLPGが配管内壁面に付着する条件を特定した。
そして、特定した条件から、LPGの気化に影響を及ぼす因子を突き止め、それを用いてLPGが気化せずに配管内壁面に付着するか否かの独自の指標を見出した。具体的には以下に示すものである。 A verification test was conducted for the case where the calorific value adjusting device is installed vertically, the degree of superheat is small, and an elbow is installed downstream of the calorific value adjusting device. did.
Then, from the specified conditions, we identified the factors that affect the vaporization of LPG, and used them to find a unique index to determine whether LPG adheres to the inner wall surface of the pipe without vaporizing. Specifically, they are shown below.

本発明は、NGが流れる主流管に設けられて基端側から前記NGの供給を受けて先端側に噴出する外筒と、該外筒内に該外筒と同軸方向でかつ外筒内壁と空間を介して配置され前記主流管から分岐した分岐管から前記NGの供給を受ける内筒と、該内筒と同軸上に配置されて該内筒内にLPGを吐出する液体ノズルとを備え、前記主流管を流れる前記NGに前記液体ノズルからLPGを添加することで前記NGの熱量を調整する熱量調整装置の後流配管内壁面に、微粒化されたLPGが付着するか否かの判定方法であって、
S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰以上であれば、LPGが配管内壁面へ付着しないと判定し、S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰未満であれば、LPGが配管内壁面へ付着すると判定することを特徴とするものである。
ここで、S_m：LPGの比表面積[m²/m³]
t：LPG液滴の滞留時間[s]
P_sat,LPG：製造ガス温度におけるLPGの飽和蒸気圧[Pa]
P_LPG：製造ガス中のLPGの分圧[Pa] The present invention comprises an outer cylinder provided in a main pipe through which NG flows and receiving the supply of NG from the base end side and ejecting the NG to the tip side; An inner cylinder that is arranged with a space therebetween and receives the supply of the NG from a branch pipe branched from the main pipe, and a liquid nozzle that is arranged coaxially with the inner cylinder and discharges LPG into the inner cylinder, A method for determining whether or not atomized LPG adheres to the inner wall surface of a downstream pipe of a heat quantity adjusting device that adjusts the heat quantity of the NG by adding LPG from the liquid nozzle to the NG flowing through the main pipe. and
If S _m × t × (P _{sat, LPG} -P _LPG ) is 1.5 × 10 ¹⁰ or more, it is determined that LPG does not adhere to the inner wall surface of the pipe, and S _m × t × (P _{sat, LPG} -P _LPG ) is less than 1.5×10 ¹⁰ , it is determined that LPG adheres to the inner wall surface of the pipe.
where, S _m : specific surface area of LPG [m ² /m ³ ]
t: residence time of LPG droplet [s]
P _sat,LPG : Saturated vapor pressure of LPG at production gas temperature [Pa]
P _LPG : Partial pressure of LPG in production gas [Pa]

本発明によれば、熱量調整装置の据付姿勢を問わず、熱量調整装置の後流配管内壁面に気化前のLPG液滴が付着するか否かを判定することができる。
したがって、熱量調整装置の据付姿勢を縦置きとし、過熱度が小さい、かつ熱量調整装置後流にエルボを設置する場合において、熱量調整装置後流配管が低温とならない指標とすることができる。すなわち、この指標を満たすように装置を製造すれば、熱量調整装置後流配管に低温材を用いなくてもよいため、材料費及び施工費の削減につながる。 According to the present invention, regardless of the installation posture of the calorific value adjusting device, it is possible to determine whether or not LPG droplets before vaporization adhere to the inner wall surface of the downstream pipe of the calorific value adjusting device.
Therefore, when the calorific value adjusting device is installed vertically, the degree of superheat is small, and an elbow is installed downstream of the calorific value adjusting device, it can be used as an indicator that the downstream piping of the calorific value adjusting device does not become low temperature. That is, if the device is manufactured so as to satisfy this index, it is not necessary to use a low-temperature material for the downstream piping of the calorific value adjusting device, which leads to a reduction in material costs and construction costs.

本実施の形態に係る熱量調整装置を縦置き・下向きとした状態を説明する図である。It is a figure explaining the state which made the calorific value adjusting device which concerns on this Embodiment the vertical installation downward. 液滴の終端速度の算出過程を説明する図である（その１）。It is a figure explaining the calculation process of the terminal velocity of a droplet (part 1). 液滴の終端速度の算出過程を説明する図である（その２）。FIG. 12 is a diagram for explaining the process of calculating the terminal velocity of a droplet (Part 2); LPG付着距離を説明する図である。It is a figure explaining LPG adhesion distance. 実証試験の各条件において、LPGの気化に影響を及ぼす因子を掛け合わせたもの（S_m×t×(P_sat,LPG-P_LPG)）に対するLPGの気化に要する距離の関係を示すグラフである。10 is a graph showing the relationship between the distance required for vaporization of LPG and the product of factors affecting vaporization of LPG (S _m ×t ×(P _sat,LPG −P _LPG )) under each condition of the demonstration test. . 従来の熱量調整装置の概要を説明する説明図である。It is an explanatory view explaining an outline of the conventional calorie adjustment device.

本実施の形態は、図１に示すように、NGが流れる主流管３に設けられて基端側から前記NGの供給を受けて先端側に噴出する外筒５と、外筒５内に外筒５と同軸方向でかつ外筒内壁と空間を介して配置され主流管３から分岐した分岐管７から前記NGの供給を受ける内筒９と、内筒９と同軸上に配置されて内筒９内に液体供給管１１からLPGの供給を受けLPGを吐出する液体ノズル１３とを備え、主流管３を流れる前記NGに液体ノズル１３からLPGを添加することで前記NGの熱量を調整する熱量調整装置１の後流配管内壁面に、微粒化されたLPGが付着するか否かの判定方法である。
具体的には、S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰以上であれば、LPGが配管内壁面へ付着しないと判定し、S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰未満であれば、LPGが配管内壁面へ付着すると判定する。
ここで、S_m：LPGの比表面積[m²/m³]
t：LPG液滴の滞留時間[s]
P_sat,LPG：製造ガス温度におけるLPGの飽和蒸気圧[Pa]
P_LPG：製造ガス中のLPGの分圧[Pa]
以下、上記判定基準の導出方法について説明する。 This embodiment, as shown in FIG. an inner cylinder 9 arranged coaxially with the cylinder 5 and spaced from the inner wall of the outer cylinder and receiving the supply of the NG from a branch pipe 7 branched from the main pipe 3; 9 includes a liquid nozzle 13 for receiving LPG supply from the liquid supply pipe 11 and discharging LPG, and adding LPG to the NG flowing through the main pipe 3 from the liquid nozzle 13 to adjust the heat quantity of the NG. This is a method for determining whether or not atomized LPG adheres to the inner wall surface of the downstream pipe of the adjusting device 1 .
Specifically, if S _m ×t × (P _{sat, LPG} −P _LPG ) is 1.5 × 10 ¹⁰ or more, it is determined that LPG does not adhere to the inner wall surface of the pipe, and S _m ×t × (P _{sat, LPG} −P _LPG ) is less than 1.5×10 ¹⁰ , it is determined that LPG adheres to the inner wall surface of the pipe.
where, S _m : specific surface area of LPG [m ² /m ³ ]
t: residence time of LPG droplet [s]
P _sat,LPG : Saturated vapor pressure of LPG at production gas temperature [Pa]
P _LPG : Partial pressure of LPG in production gas [Pa]
A method for deriving the criteria will be described below.

LPGの気化に影響を及ぼす因子は、S_m（=LPGの比表面積）、t(=LPG液滴の滞留時間)及び(P_sat,LPG-P_LPG)（製造ガス温度におけるLPGの飽和蒸気圧P_sat,LPGと、製造ガス中のLPGの分圧P_LPGの差[Pa]）であり、S_mとtは以下の式によって求められる。
S_m=(πD²)×n/F_LPG ・・・（１）
t=L/u_t,LPG ・・・・・・・・（２）
ここで、D：微粒化されたLPGの液滴径[m/個]（既往の式により推定することができる）
n：液滴数[個]
F_LPG：LPG量[m³]
L:ベンチュリ部分の長さ[m]
u_t,LPG：LPG液滴の終端速度[m/s] The factors affecting the vaporization of LPG are S _m (= specific surface area of LPG), t (= residence time of LPG droplets) and (P _sat,LPG −P _LPG ) (saturated vapor pressure of LPG at production gas temperature is the difference [Pa] between P _sat,LPG and the partial pressure of LPG in the production gas (P _LPG ), and S _m and t are obtained by the following equations.
S _m =(πD ² )×n/F _LPG (1)
t=L/u _{t, LPG} (2)
Here, D: droplet diameter of atomized LPG [m/piece] (can be estimated by the existing formula)
n: number of droplets [pieces]
F _LPG : LPG volume [m ³ ]
L: Length of venturi part [m]
u _t,LPG : Terminal velocity of LPG droplet [m/s]

ここで、LPG液滴の終端速度u_t,LPGの求め方について説明する。
液体ノズル１３から流出したLPG液滴が周囲のガスの流れによって減速されるような状況を考えると、次のLPG液滴に関する運動方程式が成り立つ。
ρ_LPGV_D(du/dt)=(ρ_LPG-ρ_Gas)V_Da-C_DS(ρ_Gasu²/2) ・・・・（３）
ここで、ρ_LPG：LPGの密度[kg/m³]
V_D：LPG液滴1 個当たりの体積(=πD³/6)[m³]
ρ_Gas：製造ガスの密度[kg/m³]
C_D：抗力係数(=24/Re，Re：レイノルズ数（=Du_tρ_Gas/μ_Gas）)[-]
u_t：LPG液滴の終端速度u_t,LPGとu₂の差(u₂は後述)
μ_Gas：製造ガスの粘度[Pa s]
S：LPG液滴1個当たりの運動方向への投影面積(=πD²/4)[m²]
u：LPG液滴の速度[m/s]
a：ガスの減速加速度[m/s²]
なお、抗力係数C_Dは、Reの範囲によって式が異なるが、LPG液滴径Dがμmオーダーと非常に小さく、総じてRe=Du_tρ_Gas/μ_Gas＜2なので、C_D＝24/Reとなる。 Here, how to obtain the terminal velocity u _{t of the LPG droplet and LPG} will be described.
Considering the situation in which the LPG droplet discharged from the liquid nozzle 13 is decelerated by the surrounding gas flow, the following equation of motion for the LPG droplet holds.
ρ _LPG V _D (du/dt)=(ρ _LPG -ρ _Gas )V _D aC _D S(ρ _Gas u ² /2) (3)
where, ρ _LPG : Density of LPG [kg/m ³ ]
V _D : Volume per LPG droplet (=πD ³ /6) [m ³ ]
ρ _Gas : Density of manufactured gas [kg/m ³ ]
C _D : Drag coefficient (=24/Re, Re: Reynolds number (=Du _t ρ _Gas /μ _Gas ))[-]
u _t : LPG droplet terminal velocity u _{t, difference between LPG} and u ₂ (u ₂ will be described later)
μ _Gas : Viscosity of production gas [Pa s]
S: Projected area of one LPG droplet in the direction of motion (=πD ² /4) [m ² ]
u: LPG droplet velocity [m/s]
a: Deceleration acceleration of gas [m/s ² ]
Although the formula for the drag coefficient C _D varies depending on the range of Re, the LPG droplet diameter D is very small, on the order of μm, and in general, Re = Du _t ρ _Gas / μ _Gas < 2, so C _D = 24/Re becomes.

ここで、ガスの減速加速度aの求め方を、図２、図３に基づいて説明する。
図２は、ノズル出口～ベンチュリ出口におけるNGとLPG液滴の典型的な流速変化を示したものである。ここで、u_Gはノズル流出時のNG流速、u₁はベンチュリのど部のNG流速、u₂はベンチュリ出口部のNG流速、Lはベンチュリ長さである。
図２に示すように、NG流速は流路が拡大していくに従って減少し、また、LPG液滴はu_Gまたはu₁のうち、大きい方の速度(=MAX(u_G,u₁))でベンチュリのど部を通過し、LPG液滴は周囲のガスによって終端速度u_t,LPGまで減速される。そして、ガス流速が時間に対して1次で減少すると仮定すると、ベンチュリ長さLは、図３のグラフにおけるグレーの部分の面積となり、下式が成立する。

Here, a method for obtaining the deceleration acceleration a of the gas will be described with reference to FIGS. 2 and 3. FIG.
FIG. 2 shows typical flow velocity changes of NG and LPG droplets from the nozzle outlet to the venturi outlet. where u _G is the NG flow rate at the exit of the nozzle, u ₁ is the NG flow rate at the venturi throat, u ₂ is the NG flow rate at the venturi outlet, and L is the venturi length.
As shown in FIG. 2, the NG flow velocity decreases as the channel expands, and the LPG droplets have the larger velocity of u _G or u ₁ (=MAX (u _G , u ₁ )) Passing through the venturi throat at , the LPG droplet is decelerated by the surrounding gas to a terminal velocity u _t,LPG . Assuming that the gas flow velocity decreases linearly with time, the venturi length L becomes the area of the gray portion in the graph of FIG. 3, and the following formula holds.

また、ガスの減速加速度aは下式によって求まる。

Also, the deceleration acceleration a of the gas is obtained by the following formula.

式（４）（５）より、ガスの減速加速度aは、下記の通り求められる。

From the equations (4) and (5), the deceleration acceleration a of the gas is obtained as follows.

LPG液滴の終端速度u_t,LPGとu₂の差u_tは、加速度がゼロとなったときの速度である。これは、（３）式の左辺がゼロとなるときであり、このとき（３）式においてu=u_tとすればu_tについて以下の式が得られる。
u_t=D²(ρ_LPG-ρ_Gas)a/(18μ_Gas)
上式において、さらに液滴の変形による終端速度の低下を考慮した補正（(3μ_LPG+3μ_Gas)/(3μ_LPG+2μ_Gas)）をかけると次式のHadamard-Rybczinskiの式が求められる。
u_t=D²(ρ_LPG-ρ_Gas)a/(18μ_Gas)×(3μ_LPG+3μ_Gas)/(3μ_LPG+2μ_Gas) ・・・・（７）
ここで、μ_LPG：LPGの粘度[Pa s]
このu_tの絶対値|u_t|にu₂を加えたものがLPG液滴の終端速度u_t,LPGとなる。 The terminal velocity u t of the LPG droplet and the difference u _t between _LPG and u ₂ are velocities when the acceleration becomes zero. This is when the left side of equation (3) becomes zero. At this time, if u=u _t in equation (3), the following equation is obtained for u _t .
u _t = ^D2 ( _ρLPG - _ρGas )a/( _18μGas )
In the above equation, the following Hadamard-Rybczinski equation is obtained by applying a correction ((3μ _LPG +3μ _Gas )/(3μ _LPG +2μ _Gas )) that takes into consideration the decrease in terminal velocity due to droplet deformation.
u _t = ^D2 ( _ρLPG - _ρGas )a/(18μGas)×( _3μLPG + _3μGas )/( _3μLPG + _{2μGas )} (7)
where μ _LPG : Viscosity of LPG [Pa s]
The terminal velocity u _{t ,LPG} of the LPG droplet is obtained by adding u ₂ to the absolute value of u t |u _t |.

図１に示す試験装置を用いて各条件におけるLPG付着距離を求める実証試験を行った。ここで、LPG付着距離とは、図４に示すように、熱量調整装置１の後流側において、配管表面温度が-5℃以下となる距離である。
想定される運転範囲において、主流管NG流量、分岐管NG流量、熱量調整装置入口NG温度、LPG流量を組み合わせた条件で熱量調整装置及び後流配管の表面温度を測定する試験を行った。
ここで、主流管NG流量はベンチュリ内のNG流速ひいてはLPG液滴の終端速度u_t,LPGに、分岐管NG流量はLPGの液滴径Dに、熱量調整装置入口NG温度は過熱度及び製造ガス温度におけるLPGの飽和蒸気圧P_sat,_LPGに、LPG流量はLPG液滴の比表面積S_m、LPGの液滴径D及び製造ガス中のLPG分圧P_LPGにそれぞれ影響する因子である。 Using the test equipment shown in Fig. 1, a verification test was conducted to determine the LPG adhesion distance under each condition. Here, the LPG adhesion distance is the distance at which the pipe surface temperature is −5° C. or lower on the downstream side of the heat quantity adjusting device 1, as shown in FIG.
A test was conducted to measure the surface temperature of the calorific value control device and the downstream pipe under conditions that combined the main pipe NG flow rate, branch pipe NG flow rate, calorific value control device inlet NG temperature, and LPG flow rate within the assumed operating range.
Here, the main pipe NG flow rate is the NG flow rate in the venturi and thus the LPG droplet terminal velocity u _{t, LPG} , the branch pipe NG flow rate is the LPG droplet diameter D, and the calorific value adjustment device inlet NG temperature is the degree of superheat and production The LPG flow rate is a factor affecting the LPG saturation vapor pressure P _{sat and LPG} at the gas temperature, the LPG droplet specific surface area S _m , the LPG droplet diameter D, and the LPG partial pressure P _LPG in the production gas.

実証試験の各条件において、（S_m×t×(P_sat,LPG-P_LPG)）に対するLPGの気化に要する距離（LPG付着距離）の関係を求めたものを図５に示す。図５の縦軸はLPG付着距離、横軸は（S_m×t×(P_sat,LPG-P_LPG)）である。
横軸を（S_m×t×(P_sat,LPG-P_LPG)）としたのは、LPG液滴の気化、すなわちLPGの物質移動に寄与する要因として考えられるもので整理したからである。
つまり、上記要因としては、(i)気液界面積（界面積が大きいほど気化しやすい）（S_m）、(ii)液体ノズルから流出したLPG液滴がどれくらいの時間ベンチュリ内に存在しているか（滞留時間t）、(iii)LPGがどれくらい気化できるか（理論的には飽和蒸気圧まで気化できる）（飽和蒸気圧と分圧の差P_sat,LPG-P_LPG）が考えられる。 FIG. 5 shows the relationship between (S _m ×t×(P _sat,LPG −P _LPG )) and the distance required for vaporization of LPG (LPG adhesion distance) under each condition of the demonstration test. The vertical axis in FIG. 5 is the LPG adhesion distance, and the horizontal axis is (S _m ×t×(P _sat,LPG −P _LPG )).
The reason why the horizontal axis is (S _m ×t ×(P _sat,LPG -P _LPG )) is that the factors that contribute to the vaporization of LPG droplets, that is, the mass transfer of LPG, are arranged.
In other words, the above factors include (i) the gas-liquid interfacial area (the larger the interfacial area, the easier it is to vaporize) (S _m ), and (ii) how long the LPG droplets flowing out from the liquid nozzle remain in the venturi. (residence time t), and (iii) how much LPG can be vaporized (theoretically, it can be vaporized up to the saturated vapor pressure) (difference between saturated vapor pressure and partial pressure P _sat,LPG -P _LPG ).

図５から、S_m×t×(P_sat,LPG-P_LPG)の値が1.5×10¹⁰以上であれば、LPG付着距離が０となり、LPGが配管内壁面に付着しないことが分かる。 From FIG. 5, it can be seen that when the value of S _m ×t×(P _sat,LPG −P _LPG ) is 1.5×10 ¹⁰ or more, the LPG adhesion distance is 0 and LPG does not adhere to the inner wall surface of the pipe.

例えば、熱量調整装置入口NG温度40℃、主流管NG流量2100m³N/h、分岐管NG流量700m³N/h，LPG流量200kg/hの条件では、S_m×t×(P_sat,LPG-P_LPG)=1.6×10¹⁰となり、しきい値である1.5×10¹⁰以上となるため、LPGが配管内壁面へ付着せず、配管が低温となることはないと判定できる。 For example, under the conditions of calorific value adjustment device inlet NG temperature of 40°C, main pipe NG flow rate of 2100 m ³ N/h, branch pipe NG flow rate of 700 m ³ N/h, and LPG flow rate of 200 kg/h, S _m ×t × (P _{sat, LPG} −P _LPG )=1.6×10 ¹⁰ , which is equal to or higher than the threshold value of 1.5×10 ¹⁰ , so it can be determined that LPG does not adhere to the inner wall surface of the pipe and the pipe does not become low temperature.

以上のように、本実施の形態の判定方法によれば、熱量調整装置１の据付姿勢を問わず、LPGが配管内壁面に付着するか否かを判定することができる。
したがって、熱量調整装置１の据付姿勢を、図１に示すように、縦置きとし、過熱度が小さい、かつ熱量調整装置後流にエルボ１５を設置する場合において、熱量調整装置後流配管が低温とならない指標とすることができる。すなわち、この指標を満たすように装置を製造すれば、図１のエルボ１５による屈曲部分（図中の破線の四角で囲んだ部分）に液滴が付着することがなく、熱量調整装置後流配管に低温材を用いなくてもよいため、材料費及び施工費の削減につながる。 As described above, according to the determination method of the present embodiment, it is possible to determine whether or not LPG adheres to the inner wall surface of the pipe regardless of the installation posture of the calorific value adjusting device 1 .
Therefore, when the calorific value adjusting device 1 is installed vertically as shown in FIG. It can be used as an index that does not become That is, if the device is manufactured so as to satisfy this index, droplets will not adhere to the bent portion of the elbow 15 in FIG. Since there is no need to use low-temperature materials for the construction, it leads to a reduction in material costs and construction costs.

１ 熱量調整装置
３ 主流管
５ 外筒
７ 分岐管
９ 内筒
１１ 液体供給管
１３ 液体ノズル
１５ エルボ REFERENCE SIGNS LIST 1 calorific value adjusting device 3 main pipe 5 outer cylinder 7 branch pipe 9 inner cylinder 11 liquid supply pipe 13 liquid nozzle 15 elbow

Claims (1)

NGが流れる主流管に設けられて基端側から前記NGの供給を受けて先端側に噴出する外筒と、該外筒内に該外筒と同軸方向でかつ外筒内壁と空間を介して配置され前記主流管から分岐した分岐管から前記NGの供給を受ける内筒と、該内筒と同軸上に配置されて該内筒内にLPGを吐出する液体ノズルとを備え、前記主流管を流れる前記NGに前記液体ノズルからLPGを添加することで前記NGの熱量を調整する熱量調整装置の後流配管内壁面に、微粒化されたLPGが付着するか否かの判定方法であって、
S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰以上であれば、LPGが配管内壁面へ付着しないと判定し、S_m×t×(P_sat,LPG-P_LPG)が1.5×10¹⁰未満であれば、LPGが配管内壁面へ付着すると判定することを特徴とする熱量調整装置の後流配管内壁面に微粒化されたLPGが付着するか否かの判定方法。
ここで、S_m：LPGの比表面積[m²/m³]
t：LPG液滴の滞留時間[s]
P_sat,LPG：製造ガス温度におけるLPGの飽和蒸気圧[Pa]
P_LPG：製造ガス中のLPGの分圧[Pa] an outer cylinder provided in the main pipe through which NG flows and receiving the supply of the NG from the base end side and ejecting it to the tip side; An inner cylinder that is arranged and receives the supply of the NG from a branch pipe branched from the main pipe; and a liquid nozzle that is arranged coaxially with the inner cylinder and discharges LPG into the inner cylinder, A method for determining whether or not atomized LPG adheres to the inner wall surface of a downstream pipe of a heat quantity adjusting device that adjusts the heat quantity of the NG by adding LPG to the flowing NG from the liquid nozzle,
If S _m × t × (P _{sat, LPG} -P _LPG ) is 1.5 × 10 ¹⁰ or more, it is determined that LPG does not adhere to the inner wall surface of the pipe, and S _m × t × (P _{sat, LPG} -P _LPG ) A method for determining whether or not atomized LPG adheres to the inner wall surface of a downstream pipe of a calorific value adjusting device, characterized in that it is determined that LPG adheres to the inner wall surface of the pipe when is less than 1.5×10 ¹⁰ .
where, S _m : specific surface area of LPG [m ² /m ³ ]
t: residence time of LPG droplet [s]
P _sat,LPG : Saturated vapor pressure of LPG at production gas temperature [Pa]
P _LPG : Partial pressure of LPG in production gas [Pa]

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