How to use fiber optic temperature measurement system for oil storage tanks in oil tank areas of the petroleum and petrochemical industry-INNO

Most fire accidents are caused by high temperatures. In the petroleum and petrochemical industry, oil tank areas are a major industrial hazard. High temperatures in large oil storage tanks can lead to oil volatilization, 火災, そして爆発さえも, causing significant casualties and property damage. 目下, the alarm data of commonly used oil tank fire automatic alarm systems comes from the fiber Bragg grating temperature measurement system TBG. This type of sensor can only perform scattered measurement. 同時に, during installation, it is necessary to drill holes and weld on the oil tank wall panel or directly input it into the tank to measure the temperature of liquids and gases, which is inconvenient for both early construction and later maintenance. これに基づいて, ザ分散型光ファイバー温度測定システム DTS は、くすぶっている火災時の温度監視に適用できます。 (少量の煙と熱が発生します), 警告を出す, 現場のオペレーターに、事故や火災を回避するための対応措置を講じるための十分な時間を与えます。. 同時に, 企業の安全管理の自動化レベルを効果的に向上させることができます.

分散型光ファイバ温度測定システムの原理

の主な作業基盤は、分散型光ファイバー温度測定システム光学式時間領域反射率計の原理 (OTDRの) 光ファイバーにおける後方ラマン散乱の温度効果.

OTDR原理は主に光ファイバーの位置決めに使用されます, オイルタンク内の温度場の空間分散配置を実現できます。, 光ファイバーのさまざまな部分の損失を確認する (ダメージ箇所も含めて), 温度測定ポイントを特定します.

Backward Raman scattering effect refers to the phenomenon where when a laser source in the main processing unit injects a pulse signal with a wavelength of 905nm into a fiber, although the propagation speed of light is fast, it still has a certain degree of attenuation. Some scattered light will propagate in the opposite direction of the incident light, and the Raman signal contained in the scattered light carries temperature field information. This signal is processed through a digital signal processing system (DSP) to provide information about the temperature field distribution of the storage tank and output a temperature distribution map on the entire fiber.

Design of Distributed Fiber Optic Temperature Measurement System

The distributed fiber optic temperature measurement system must ensure the following three points: it can provide early detection of oil tank fire hazards; Can clearly indicate fire hazard locations; Send fire information to the fire alarm control system, activate the emergency control system, such as closing the emergency shut-off valve, cutting off oil pipes, and other emergency operations.

The layout of the equipment must be combined with the structural characteristics of the oil tank, taking into account comprehensive coverage and convenient installation. The entire control system is divided into automatic control and manual control according to the requirements of the fire alarm control system, and manual control is given priority. Automatic control: Once the temperature value of the measured oil tank exceeds the standard set alarm temperature, the distributed 光ファイバー温度監視システム sends real-time fire alarm data to the fire alarm host. The alarm host receives a relay action monitoring signal and confirms it as a fire alarm through logical judgment system. Manual control: once a person finds a fire and the alarm system has not been started, he can press the emergency manual alarm button. The fire alarm host receives the button alarm signal, the system confirms that it is a fire, and immediately enters the fire treatment program. The alarm host will then send an audible and visual fire alarm to the relevant areas and display it. 同時に, it will link the corresponding fire hydrant system, automatic foam spray system, 等。, and upload the alarm signal to the oil depot management office, so as to organize personnel evacuation and rescue work in a timely manner.

The entire monitoring system consists of a DTS control unit, 温度センシング光ケーブル, and fiber optic connectors, which can be linked with other systems to form a fire alarm control system,

DTS control unit

The DTS control unit is debugged and programmed by authorized personnel in the human-machine interface environment through an engineer station. The area length and alarm points can be set according to needs, and the temperature trajectory of the optical cable can be displayed in real time on the PC. The alarm signal can be highlighted, including the determination of the actual location of the damaged point of the optical cable. エリア設定や警報点位置も必要に応じて変更可能. 同時に, 温度測定システム全体をリレー出力を通じて他の制御システムと相互接続し、論理的な判断を実行できます。. 防火用途において, 火災警報制御ホストに接続して、音と光の警報信号を提供できます。, 正確かつ完全な信号出力; DTSコントロールユニットは各種デジタル表示装置に信号を直接出力可能, 中央制御室プロジェクターなど, ディスプレイ, 等。, 共有レベルに基づいて情報共有権限を設定できます.

温度感知検出用光ケーブル

温度感知光ファイバーケーブルはシステム全体のフロントエンドデバイスです, DTSコントロールユニットの判定結果に直結. オイルタンクの外壁に設置可能. 各ゾーンのアラーム検出ロジックの判定は3つの方法を任意に組み合わせて使用可能: ゾーン内の最高温度 (一定温度), ゾーン内の温度上昇率 (温度差), ゾーン内の最高温度とゾーン内の平均温度の差 (ゾーン温度の均一性) 早期かつ確実に警報を発し、くすぶりを防止します。. 同時に, 石油タンクエリアのレイアウトは過酷な環境にあることが多いことを考慮して, 温度感知検出光ケーブルは耐噛み込みなどの優れた特性を備えている必要があります, 耐震性, 耐食性, 等. 光ケーブルには頑丈なシースが必要です (PVC難燃性素材), 優れた保護特性を提供できます. 同時に, また、火災を迅速に検知できるように、良好な温度伝導性も備えている必要があります。. The longest detection distance for a single channel is 30KM, and the number of channels can be expanded to 16. The positioning accuracy can reach ± 0.5m. The fastest response time for a single channel is 3.5s, and the startup preheating time is instant use.

The attenuation of the entire system optical cable shall not exceed the standards of the DTS control unit. The maximum attenuation rate on the 2km optical fiber shall not exceed 10dB, each junction box shall not exceed 0.4dB, and each fusion joint shall not exceed 0.2dB.

Fiber optic connecting devices

The fiber optic connecting device serves as the hub for connecting the temperature sensing detection optical cable to the DTS control unit. The tail fiber and the detection optical cable are connected through fiber optic fusion points, which are located in the fiber optic connection box next to the DTS control unit.

Distributed fiber optic fire detection system

According to the design requirements, there are a total of 4 external floating roof crude oil tanks and 5 internal floating roof finished oil tanks in the oil tank area, which are equipped with fiber optic fire detection systems. Install a fiber optic temperature fire detector at the sealing ring of the floating plate of the floating roof tank, and add twice the vertical laying length. The required detection optical cable for winding a oil tank is about 196m. Based on the above data calculation, taking 1.15 times the effective redundancy, the required optical cable for the storage tank is 2028m.

Based on the distribution characteristics of oil tanks and specific requirements for temperature monitoring, this project adopts a “one tank, one machine” mode for design. 同時に, to increase system stability, dual machine hot standby is adopted, which can automatically switch in case of system failure. 合計 9 fiber optic distributed temperature monitoring systems are used to monitor the required oil tanks in real-time online.

1) Each tank is monitored by an independent sensing optical fiber, which is installed on the floating plate of the tank and at the outer edge of the secondary sealing ring.

2) The anti-static optical fiber led out by the 光ファイバー温度センサー installed on the floating plate inside the tank is protected by laying an explosion-proof metal hose with a diameter of DN25 inside the tank. 防爆金属ホースの上端はタンク上部のマンホールのフランジに固定されています, 金属ホースの下端はタンク内のフローティングプレートに固定されています. 固定方法は非熱間加工です, 防爆金属ホースはタンク本体に等電位接続されています。.

3) 浮き屋根式タンク上部の変位変化を考慮して, 防爆金属ホース内を通過する帯電防止光ファイバの引きずりによる誤動作を防止するため, 予約された長さは以下であってはなりません 0.5 タンクの外壁の高さの倍, 特定の位置領域で帯電防止光ファイバーを制御するには、ディスク光ファイバーデバイスを使用する必要があります。.

4) タンク内の浮き板に設置された光ファイバー温度センサーから導かれた帯電防止光ファイバーは、タンク外周部の直径DN25の防爆亜鉛メッキパイプを通し、エスカレーターまたはタンク壁に沿って既存の地上幹線まで導かれます。. トランキング内に敷設された通信光ケーブルと防水光ケーブル接続箱を介して接続・保護されています, エルボ部は防爆メタルホースで接続されています.

5) タンクエリア内の各石油タンクの浮き屋根に取り付けられたすべての光ファイバー温度センサーは、帯電防止光ファイバーを通じて引き出され、信号の収集と監視室への送信のために通信光ケーブルに集中します。. 通信用光ケーブルを直接埋設, エルボは防爆メタルホースで接続されています.

6) 通信用光ケーブルをタンクエリアから監視室まで伝送した後, 標準の光ファイバーコネクタを備えた短距離光ファイバーテールを介して、DTS ホストに対応する検出チャネルインターフェイスに接続されます。, これは光ファイバージャンパーです.

7) 9 台の 2 チャンネル DTS 分散型光ファイバー温度測定ホストを監視室に配置し、温度信号を取得しました。, 温度上昇警告, 過熱アラーム, 故障検出, 石油タンクサイトに設置された光ファイバー温度センサーの情報管理業務. They can be connected to the fire alarm control system through the switch alarm interface to achieve fire alarm and display it in the fire duty room. The current temperature value, アラームステータス, and historical temperature curve of all temperature sensing points of the storage tank can be visually displayed in the instrument operation room through the electronic map of the configuration software. An external sound and light alarm can also provide alarm signals in the instrument operation room.

The distributed fiber optic temperature measurement system can detect the temperature value at every point along the fiber optic cable in real-time online, and can determine the trend of fire spread; Multiple alarm methods such as temperature difference and temperature rise rate can be set, and multi-level warnings can be set up to achieve early warning before a fire occurs; Alarm zones can be set arbitrarily according to changes in on-site conditions, and each zone can set different alarm values; It can withstand harsh environments, 電磁干渉に抵抗する, and does not generate electromagnetic radiation. The effective lifespan of the detection optical cable is 30 月日, overcoming the high false alarm rate and maintenance difficulties of the point type fiber optic grating temperature measurement system. It has reference significance for the fire safety of future oil tank areas.