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SECTSkin effect trace heating

Control system

For enhancement of efficiency SECT System is equipped with control system that reduces power output in response to

ambient temperature increase. That ensures reliable control of heating system status and emergency conditions.

SECT system efficiency in comparison with other heater types

Calculated temperature distribution

An example of heating heat-insulated

pipeline by three SECT system heating

elements with total power output 130 W/m.

Pipe diameter 530 mm,

ambient air temperature -20°C.

Depending on heating power needed and pipeline

length, SKIN SYSTEM may consist of one, two or

three

(as is shown on the figure) heating elements.

Temperature range of calculation

-40 – +200°C

Power supply:

up to 3 kVAC 50 Hz

Construction:

Heat-generating element — tube of low-carbon

steel 20–60 mm in diameter with 2-4 mm wall

thickness

Current carrying conductor – Special conductor

resistive to high voltage (up to 3 kV), high

temperature (up to 200°C) and mechanical stress

at installation

Anticorrosive insulation of heating element — Epoxy coating(on customer's request)

Accessories

Full range of accessories is available including distribution, connecting and terminal boxes and couplings, fastenings and

control units (controllers and control cabinets).

4) SECT System Diagram

5) Commercial proposal SEHMS General technical description

Summary description of SEHMS Pipeline electrical heating system in which unique technique is realized using skin-effect physical phenomenon (hereafter referred as SEHMS) is designed for heating of long and extra long pipelines including buried ones as in the given project. SEHMS is the only industrial heating system being a cost-effective method of heat tracing of long and extra long pipelines to ensure normal flow of the product. In the SEHMS special heating elements are applied, which use SKIN-effect and proximity effect in ferromagnetic conductors at alternative power current. The heating element is a low carbon steel tube with the wall thickness not less than 3mm, inside of which a non-magnetic conductor (copper) is placed. At the end of the run the conductor is connected to a steel pipe, and at the beginning of the run alternating voltage is being applied between the pipe and the conductor. The voltage value is calculated taking into account the heat generation required and the length of the heated segment.

Fig. 1.2.1

Alternative current runs through the whole inner conductor section. No significant surface effect arises in nonmagnetic material with good conductivity. In the outer ferromagnetic conductor (steel pipe) the SKIN-effect is clear cut and the whole current runs through the internal pipe layer with about 1mm thickness. The potential of external surface of pipe keeps on being virtually zero. Due to light thickness of the SKIN-layer, basic heat generating (up to 80%) is being performed in the steel pipe. At the beginning and at the end of the circuit (heating pipe segment) the outer surface of the SKIN-tube is reliably grounded what ensures additional safety of the SEHMS system. SEHMS advantages

Minimum quantity of heating elements power supply points. According to the designing experience of these systems, the maximum length of ONE LINE of SEHMS may be up to 10 000m. By boosting two segments of the line from one point, the distance between power supply points may be up to 20 000m. Less investment costs against other heat tracing systems. That is supported by the fact that in SEHMS SKIN-cable of a big section is discharged from heat generating and in fact performs the function of an integrated covering power network. Electrical safety. The external surface of heating element (tube) has a zero potential against earth, it is grounded and shields and protects completely the current-carrying conductor located inside. Good thermal contact. Metal heat generating element (tube) is welded directly to the main pipeline or is tightly attached to it by using special elements. For improved heat transfer a special heat conductive paste is applied. Reliability. Strong heat generating elements in form of steel tubes provide mechanical strength and protection of current-carrying conductors from damage. Heat generating elements do not have outer insulation, which can be damaged while installing.

Basic engineering data

Case 1> HUCHEMS area 5Km project 1-1. Input data and Technical requirements The current project includes the construction of a 6” MNB pipeline, insulated with 10mm aerogel (conductivity: 0.014 W/m·oC, ambient temp 10oC) heated to a max temp. of 22 °C. Temperature in empty pipe or stagnant product shall be maintained at 20 °C. The heater element will be installed in one 27 mm carbon steel tube, strapped every 30 cm along the length, located at 45o of the vertical at the bottom of the pipe. The output heat in the heat tubes should make up 27 watts/meter for the section to maintain a pipeline temp of 20 °C. The SKIN-EFFECT system will consist of one heating section. Power feeding will be carried out in one place at the end of the pipeline. Electric cubicles should be of the indoor metal enclosed and should contain all electrical protective, indicating and operating devices including sequential control and fault indicators. 1-2. Heat engineering calculations According to BS 6351, calculation of heat loss from the pipeline surface is being performed according to the following formula: P=(2πλ*ΔT×l)/ln(d2/d1) where: P – power loss intensity, W, λ - effective heat conductivity factor, W/m·°K, ΔT – temperature difference between the heated surface and the ambient air, K, d2 – outer diameter of the thermal insulation, m, d1 – inner diameter of the thermal insulation, m, l – length, m.

Table 1-1

No Pipeline designation

Diameter, inches

Length, m

Insulation thickness,

mm

Thermal specifications, °С Account safety factor

Calculated linear heat

loss, W/m

Required for product

Ambient, min.

1 Mono Nitro Benzene 6 5 000.00 10 20 -10 1,2 27

Technical solution

According to performed calculation the electrical heating system meets your technical requirements and can be realized by installation of one induction-resistive heater along the pipeline, having linear output 27 W/m Powering of the electrical heating system is realized in one place.