Build-in Mineral Insulated Electric Heater for Gathering and Transportation Pipeline is used on the application with heating cable directly inserted into pipeline for heat 100% input into the pipeline. The gas or liquid media in the pipeline is heated or temperature maintained accordingly. It is especially suitable for the heating of oil well gathering pipelines in low-yield period, promoting flow of crude oil in pipelines, reducing well pressure and ensuring oil recovery.

This heater can replace wellhead heater. The special advantage is that when an accident of pipeline condensation occurs, continuous heating can be used to gradually melt the condensed medium in the pipeline to make the material inside the pipeline reflowed.

The required use condition is that the laminar flow status of medium flowing within the pipe should be confirmed.

Second, system composition

Figure 1 Structure of the built-in electric heater for pipeline use

The built-in electric heater for pipeline use is mainly composed of three major components:

1 built-in componentized Mineral Insulated heating cable,

2 temperature detection and control unit,

3 built-in electric heating pipe structure,

These three components should be prefabricated at the factory and supplied in set by the supplier.

The temperature detection and control unit is assembled in a temperature control box;

The built-in electric heating inlet structure consists of a 30° miter tube (DN57X4) and an explosion-proof electrical junction box.

1. Built-in componentized Mineral Insulated heating cable

It is the main component used for heating and heat trace for the medium in the pipeline. The MI heating cable is manufactured into a component by the factory. It is a non-standard device, and the tail tip can be matched with the ball end of the pipe wearer to facilitate the installation into the process pipe. The electric heating power needs to be determined according to the medium, the conveying amount, the conveying distance and the environmental conditions of each well outlet.

The componentized mineral insulated heating cable in pipeline is made of metal and has a seamless welded seal. Its metal sheath can be directly contacted with the medium in the pipe. According to the anti-corrosion grade of the metal to the medium’s process temperature, the metal sheath materials available for selection are mainly copper, white copper, stainless steel or 825 alloy. The maximum continuous operating temperature for the copper sheathed heating cable is +250 ℃, white copper +400 ℃, and stainless steel +600 ℃. For application with temperatures lower than +120℃ and for special corrosion protection purposes, chromeplate copper or MI heating cable with F46 plastic outer sheath may be used.

The componentized MI heating cable can be a U-shaped single core cable, two cores, or three cores. For built-in electric heaters over 9 kW, a three-core combined three-phase star connection is generally recommended for power balance considerations.

2. Temperature measuring element

The temperature measuring element uses a metal sheathed thermocouple. Ways are: E or K indexing

The measurement points can be selected in the following three positions:

1) measuring the end temperature of the pipe flow direction;

2) the end temperature of the auxiliary heating section;

3) Measuring the temperature of 5~10 m point away from the outlet section of well, and check the relative set value of the instrument in the temperature control box by flow rate, input electric power and actual manually measured pipe end temperature

3. Temperature control box

The temperature control box is independently installed in the safe area of ​​the wellhead with outdoor structure and an IP56 protection class. The temperature control can be determined by user for mainly options of position control, time-break pulse control and smooth precision control. For details, please refer to the product manual “Electric Heat Control Cabinet” of our company's.

4. Structural component for built-in pipeline electric heater

Structural component for built-in pipeline electric heater is

customized at the factory, mainly including 30° mitered pipe (standard DN57X4), inlet mechanical seal, flange and explosion-proof junction box. The 30° mitered pipe is generally installed on the vertical riser of the pipe outside the tree. The miter tube is made of steel and welded to the outer tube. The basic specification of the welding arc is capable of being matched with the outer diameter DN57; DN60; DN76; DN89.

5. Built-in auxiliary heater

Some wells require that the temperature of the viscous liquid medium coming out of the tree should be increased firstly to reduce the transport resistance of the initial section of the medium. At this time, it is necessary to add a built-in auxiliary electric heater to add heat in the inlet section. The built-in auxiliary electric heater is independently configured. The component device, usually located in the tree, of mineral insulated (MI) heating cable is prefabricated in plant. Heating is completed in the pipe section at a distance of 20-30 m away from the tree.

Third, working principle

The built-in electric heater is a purely resistive electric heating load. The thermal energy is radiated through the metal sheath of the MI heating cable to heat the surrounding medium to achieve temperature rise or heat preservation. The whole process is completed in the conveying pipeline.

The system electrical block diagram is shown in Figure 2.

Figure 2 Electrical Block Diagram.

Fourth, model description and performance characteristics

1. Model Description

Built-in electric heater

2. Performance characteristics

1). High thermal efficiency: The heating body of the built-in electric heater is placed in pipeline with full contact to internal medium. The generated thermal energy can be 100% absorbed in pipeline, so the thermal efficiency is high.

2) Stable performance: The materials of MI heating cable and temperature measuring cable are made of inorganic insulating materials. Their physical and chemical properties are quite stable at their rated service temperature.

3) Long service life: metal sheath of MI heating cable and temperature measuring cable are sealed, seamless, mechanically strong and no heat aging. The sheath material resistant to medium corrosion can be used to ensure long-term service life for more than 30 years.

4) Easy to install: The product is built into the pipeline without internal fixing, and the external connection is simple.

5) Safe and reliable: The complete set of products is equipped with reliable electrical protection measures, and its automatic operation is safer, more explosion-proof and reliable, and fully meets the HSE management standards for oil and gas fields.

3. The main parameters

3.1 Built-in electric heater (three-core component heating cable as an example)