C.Y. Chu

A possible alternative approach to the thermal insulation of pipelines

The concept of internally lining pipes to achieve the required degree of thermal insulation is examined with respect to minimising the rate of energy losses. Suggestions are made concerning the optimal dimensions for district-heating horizontal pipelines conveying hot water at 95°C. These design recommendations arise out of the presented analysis for minimising the total rate of financial expenditure upon energy for pumping and heating the water.

Optimal pipeline geometries and oil temperatures for least rates of energy expenditure during crude-oil transmission

A mathematical model has been developed to describe the energy behaviour of a hot oil being pumped through a thermally insulated pipeline. With this model, for each specified application, predictions can be made of the interrelated optimal pipe size and temperature distribution along the pipeline corresponding to which ensues the least overall steady-state rate of energy expenditure due to thermal and hydraulic losses. In particular, the evolved iterative computational technique has been applied to the design of long (>100 km) crude oil pipelines. It is also relatively simple to extend the presented analysis in order to determine the optimal numbers of reheating and booster pumping stations necessary along the pipeline for any specific application.

Performances of internally lined pipelines for LNG

For an internally insulated pipeline conveying LNG, an optimal insulant thickness exists which corresponds with the least rate of financial expenditure upon pumping and refrigeration power. For some situations likely to be encountered, values of this optimal thickness have been predicted.

Internally insulated hot-oil pipelines

Heavy-fuel oil is usually heated to facilitate its conveyance through pipelines. This paper presents the theoretical reasoning behind the prediction of the optimal thickness of insulant necessary for such a pipeline, so that the least energy running cost can be achieved.

Internally insulated pipes for district-cooling systems

A method is presented whereby, for any set of prescribed conditions, an optimal thickness of a thermally insulating internal lining may be determined for pipes to be used for the conveyance of chilled water. The optimum investigated in this paper corresponds with the minimum total rate off energy dissipation costs as a result of refrigeration and pumping. The overall optimal design cannot be decided at this juncture without a knowledge of such unknowns as the capital cost of internally lining the pipe.

Materials for internally lining pipes

Internal lining is a well established practice for inhibiting corrosion and/or erosion within pipelines. This brief survey of protective lining materials and their properties indicates those liners which will probably be suitable for the internal thermal insulation of pipes.

Optimising the performance of internally insulated pipelines for conveying superheated steam

Design recommendations are proposed for internally insulating pipelines conveying superheated steam at 200°C, so that energy running costs are minimised. The sensitivities of the optimal thickness of the insulant to changes in the more important influential parameters are discussed.

Optimal internal lining of pipes to achieve energy conservation

An energy analysis leads to expressions for the optimal thickness of an insulant applied as an internal lining to a horizontal pipe which is intended to convey a hot liquid by steady-state, laminar flows. Numerical predictions of use to a designer are presented in simple, but generalised, graphical forms.

Recent advances concerning materials and processes for forming pipes with thermally-insulating linings

Internal lining of pipes is becoming more popular. The properties of several prospective lining materials are presented, together with a new design of co-extrusion feedblock for a three-layer relatively lightweight, yet mechanically strong, thermally insulated pipeline.

Efficient pumping of hot liquids through horizontal, internally insulated pipes

An optimal thickness exists for the internal, thermally-insulating lining of each length of pipe through which a hot liquid is pumped. Corresponding to this condition, a minimum total rate of energy loss from the pipe and pump occurs. The analysis presented in this paper enables the optimal thickness of insulant to be predicted as a function of the liquid properties and pipeline characteristics (e.g. roughness of the lining/liquid interface) for various assumptions.