Isollat Materials for Thermal Insulation of Tanks

Isollat Materials for Thermal Insulation of Tanks

Author: Director General for SPECIAL TECHNOLOGIES LLC V.S. Belyaev, Doctor of Chemistry

We have come to the point when active use of the intellectual potential, which has been created and accumulated in Russia throughout all the previous generation (of both pre-Soviet period and subsequent periods), have become urgent. The resources, which appear in the form of people, who are capable of research and implementation of break-through scientific, technical, and technological ideas, constitute, probably, a major resource of any country. A country that fails to use such resources is not unlike a country, which possesses huge underground deposits of oil, gas, gold, and diamonds, but does not use them. The generally recognized factor of richness of Russia’s natural resources should have long been added up with the intellectual potential, which, for several reasons (the main of them consisting in absence of market relations throughout an extended historical period), have not to date been actualized in the form of breakthrough technologies in most spheres. The brilliant technological breaks-through were achieved only in the spheres, where the State, striving to solve the questions of life and death for its own purposes, set the specific tasks before scientists and engineers.

Special Technologies LLC was established in 2002. With almost no material resources, except for an ardent desire to use the intellectual potential of our own and of the many Russian scientists, we launched our first project: creation, promotion, and commercialization of the new liquid ceramic thermal insulation Isollat, which had a wide range of applications and was patented in 2003. Before 2005, the product was fully certified. Later, we received 7 more patents for development and application of the product, 1 patent for our second project (development of diamond-like coatings), and 4 Trademark Certificates. From January 2005, the company’s sales and production output grew abruptly. The growth continued in 2006, 2007, and 2008; during the crisis year of 2009, the production output remained at the 2008 level. Currently, the total area of our own-developed and own-constructed facilities amounts to 1,600 square meters.

In the oil and gas sector, just like in other spheres, various thermal insulation materials are of great demand. The problem of efficient but, at the same time, compact insulation is very important in the following situations: the pumping-over of crude oil in pipelines; storage of heated fuel oil as a backup fuel in large tanks; protection of floating fractions (benzene and kerosene); insulation of individual assemblies of gas-pumping turbines and other process equipment.

Isollat is essentially special water dispersion for thermal insulation and anti-corrosive coating of any surfaces. This is a polymeric composite material, which includes hollow ceramic or silicate micro-spheres filled with rarefied air. Therefore, the coating has low thermal conductivity and a high capability to reflect 90% of incident rays of light and to scatter up to 90% of IR rays. Various combinations of fillers provide for special properties of the material including high-temperature insulation up to 500⁰С, fire resistance, seismic resistance, and corrosion resistance. The Company currently mass-produces 5 modifications of Isollat materials; besides, we have new developments. Thanks to special manufacturing technologies, Isollat is twice cheaper than the foreign equivalents, thrice lighter, and leaves them behind in terms of thermal protection properties. As of today, the Company has developed, tested, and launched production of the Isollat-Nano modification, which contains nano-particles, and features, along with thermal protection coating properties, the ability to self-clean from organic contaminants with the help of photocatalysis effect. Use of this material as, for example, a paint coating for facades of the buildings will enhance their energy efficiency and make the appearance of the façade intact and durable for the long period of its operation.

The efficiency of using Isollat coating as a means of reducing the heating of tank-stored benzene and kerosene, which is caused by exposure to sun rays and brings about evaporation of the stored substances, may be illustrated by the following modeling experiment. Fig. 1 shows a metal surface exposed to sun rays at an ambient temperature of +16⁰С. Part of the plate was coated with 1, 2 or 3 layers of Isollat (in the picture, this portion of the plate is shown in white). After application of Isollat coating, the plate was placed outdoors and exposed to sun rays, heat, rain and snow for 15 months. Then, it was inspected using a thermal imaging device. Temperature readings were taken on both sides of the metal plate at the ambient temperature of +16⁰С.

The non-coated surface of the metal plate was heated, due to sun exposure, to 42⁰С on both sides; whereas the temperature of the plate portion, which was coated with Isollat, amounted to 24⁰С in the 3-layer zone (red line) or 26⁰С in the 2-layer zone (blue line) – both on the coated side and on the back side.

The temperature inside and outside a modeled metal house behaved in a similar way.

According to the above measurements, sun radiation during the warm season may heat a non-insulated surface of sun-exposed tank zones to temperatures exceeding 45^оС. Density of the heat flow, which is directed through the tank wall towards the inside of the reservoir, is (0.7-1.1) kW/m². All these factors bring about quick heating of the benzene, which is adjacent to the wall (i.e. located near the metal surface), and convective displacement of such benzene to the upper portion of the reservoir. Since the boiling temperature of this oil product is approximately 40^оС, what we have to witness as a result is the intensive process of evaporation and accumulation of benzene vapors in the upper portion of the tank (in the air cavity above the oil level).

For example, for a vertical cylindrical 1000 m³ tank (D10.43 m × 12.01 m), we can calculated benzene heating caused by sun exposure throughout the daylight hours. Surface area of such a tank is 477 m². Assume that the sun-exposed portion (taking into account the top cover) totals approximately 2/3 of the full area of the tank, and is 318 m². This portion will be exposed to a total sun radiation heat flow of approximately 318 kW, or 273,000 kcal/h. Knowing that benzene heat capacity С=0.47 kcal/kG·⁰С and its density ρ=0.73 kG/L, and assuming that the emissivity factor of the surface is 0.9, we can calculate the sun exposure-caused temperature rise during the 12-h light day in summer season.

However, taking into account the heating of the side surface and the top cover of the tank, we can assume that the heated surface will, by convection, be displaced to the upper layers, and the temperature in upper layers (since there is no heating for the lower layers) is likely to be considerably higher than the temperature calculated for the entire amount of benzene. Temperature in the upper layers may rise twice or thrice or even more times greater (the more so, because the top cover is the most heated component). In other words, at an ambient temperature of 20-25⁰С, temperature in the upper layers may considerably exceed the benzene boiling temperature.

Isollat thermal insulation coating features a high factor of reflection and scattering of solar radiation and IR radiation (over 90%) and low thermal conductivity. Therefore, after insulation of the metal tank surface with Isollat, one may expect that the temperature on the surface of the metal tank wall considerably decrease, the process of accumulation of solar heat reduce, and, as a result, benzene evaporation losses become significantly lower.

In a similar way, Isollat coatings can be used to prevent overheat of liquefied gas stored in appropriate tanks.

Use of Isollat coatings is also highly efficient in conditions of storage of heated fuel oil as a backup fuel in large tanks.

As an example of application of the liquid ceramic Isollat coating for thermal insulation of a stand-up reservoir for fuel oil (RVS-20000), we can provide calculations of heat losses at such reservoirs, two of which were coated at Mozyr Oil Refinery (Belarus) in 2007 and 2008, and have proved successful in the course of time.

Time for fuel oil cooling in RVS-20000 reservoir from 35⁰С down to 10⁰С at ambient temperature of –20 ⁰С and thermal protection using 2-mm thick Isollat 02 (03) will be longer than 11 days.

Liquid ceramic Isollat coatings demonstrate their high efficiency for thermal insulation of outdoor gas pipelines or oil ducts.

Thus, for example, the following calculations can be provided in respect of thermal insulation of a gas pipeline segment with minimum ambient temperature of –43⁰С and with minimum gas temperature at gas flow rate metering station outlet of +3.9 ⁰С, in conditions where thermal insulation was applied in order to prevent natural gas temperature drop in the pipeline to below -20⁰С:

The calculations were done for thermal insulation of the above-described facilities with Isollat-Effect coating. One should understand peculiarities of the Isollat coating, which works more efficiently in conditions of availability of additional air gaps, since such gaps allow the coating to demonstrate optimum performance.

The calculation for the thermal insulation layer was based on guidelines provided in the Construction Norms and Regulations SNiP 2.04.14-88, 41-03-2003 “Thermal Insulation of Equipment and Pipelines” (calculations for changes in the temperature of the medium being transported). Numerical calculations taking into account all the specified features and parameters of the gas pipeline and the heat carrying medium (natural gas) were done in Mathcad.

Results of temperature calculations are provided in the table below:

For the case of use of Isollat coating for thermal insulation of outdoor process equipment and pipelines at a booster pump station platform with oil loading station and at a separate oil loading station near a cluster of wells (Udmurtia Region) at minimum possible temperature of minus 50°С, in order to reduce heat losses and to prevent drop in the temperature of the heat carrying medium (oil) to below +5°С, the following calculation may be provided as an example for thermal insulation of oil pipelines and reservoirs. This calculation was also done in accordance with SNiP guidelines in Mathcad. At a booster pump station platform with oil loading station, thermal insulation of 200-m long pipelines of various diameters (100, 150, 200 or 250 mm), tank assemblies V=200 m³, gas and oil separator V=50 m³, horizontal gas dryer V=25 m³, with the temperature of the heat carrying medium (oil) amounting to 10^оС may be done using Isollat-02 or Isollat-03 of total thickness 2.5 mm

At an oil loading station platform near a cluster of wells, due to a considerably lower flow rate of the substance in the oil and gas flows and the saving of expenditures, thermal insulation of 100-m long pipelines (dia.80 and 100 mm), tank assembly V=25 m³, gas and oil separator V=6.3 m³, with the temperature of the heat carrying medium (oil) amounting to 10^оС, is recommended to be done using combined Isollat-Effect coating.

Thus, thermal insulation coatings Isollat may be recommended as efficient and, at the same time, compact materials, which help solve most thermal insulation problems at oil and gas facilities that require such insulation. The examples provided above do not cover all possible Isollat application. It should also be noted that Isollat coatings are easily applied (the ease of application is comparable to ordinary painting activities). What else is worth mentioning is the durability of the coating in practical use (the micro-spheres minimize the factors, which deteriorate the coating; they prevent UV radiation from penetrating into the coating and preclude active effect of thermal damaging factors) and its anti-vandal properties.