REDUCTION AND REPLACEMENT OF FOSSIL FUELS - NHUMO

THE COMPANY

NHUMO is a medium-sized petrochemical company located in the industrial area of Altamira, in the state of Tamaulipas. It is the sole Mexican producer of carbon black, a material found in many commonly used articles such as drive belts, automotive hoses, shoe soles, and pigments. Carbon black also plays a significant role in industries such as tire manufacturing.

With an installed capacity of 120,000 tons per year, NHUMO covers 95% of the domestic market, which is a priority in its business strategy, while exporting 25% of its total production to North America, Central America, and Europe.

Since 1991 NHUMO has belonged to GIRSA (Grupo DESC), which currently owns 60% of its shares. The other 40% is in the hands of Cabot Corporation, a United States world leader in the marketing, production, and technology for the manufacture of carbon black.

When GIRSA acquired NHUMO, it was considered one of the most polluting companies in the Altamira industrial area. Operating conditions at the plant itself, as well as the quality of life in nearby communities, were discouraging. Faced with this situation, in 1991 the company's upper management began to establish a strategic plan to make its processes eco-efficient and safe and thereby reduce the pollution of air, water, and land.

With an awareness of the needs of clients involved in global industry, NHUMO has invested in making significant improvements in its processes, decreasing its costs, and advancing the quality of its products and services. As a company, it has a commitment to caring for and conserving the environment, as well as a sense of responsibility toward the community, while also striving to ensure that its product exceeds customer expectations.NHUMO has certified its processes under the ISO 9002 standard since 1994, and on 25 April 1997 itbecame the first international producer of carbon black to be recognized by ISO 14001 certification.

THE PROCESS

The process for obtaining carbon black involves the following stages:

  • Pre-Processing Phase. The process begins in storage tanks for the raw material, which is a thick, heavy oil containing a high ratio of compounds known as "aromatics," which are essential for the production of carbon black.

  • First Phase. Reactors are fed with air, natural gas, additives, and conversion oil at the reaction area, and are fired at a temperature ranging from 1,500 to 1,700°C. This produces carbon black, in the form of an extremely fine powder, in addition to waste gases.

  • Second Phase. The carbon black is separated from waste gases, using fiberglass bags inside the circular compartments of filtration units. Filter temperature is maintained between 200 and 270°C.

  • Third Phase. The product is pelletized to make it more dense and to provide it with some of its physical properties. The carbon black, together with water and additives, is circulated through a cylinder with a central shaft that has protruding needles or pins. Due to the high speed at which this shaft spins, the powder is transformed into grains or pellets. These pellets are much more dense than the starting material, which facilitates its handling and incorporation into rubber in the mix for the product to be manufactured. The wet pellets are then sent over to the next phase.

  • Fourth Phase. The wet carbon black goes into spinning dryers, which evaporate the water used during the densifying process, and the product comes out with less than 1% moisture. These dryers are heated by gas combustion within their enclosures.

  • Fifth Phase. The material is mechanically conveyed to storage silos and from there is sent to customers in sacks, supersacks, or in bulk. Hopper trucks for highway transport or railway hopper cars for rail transport are used for bulk shipments.

STRATEGIES IMPLEMENTED

NHUMO’s Environmental Management System (EMS) identified operations, activities, or products that were causing pollution, then determined which were the most significant so that the company could control them operationally.

The next step was to set annual environmental objectives, goals, and programs for each department. The primary goal was to avoid and/or eliminate the most significant environmental issues. Projects were incorporated into these environmental objectives and goals to enable a reduction of fossil fuels and wastewater effluents, such as the project for reducing consumption of electrical power and the project for "zero discharge to the ocean." Parallel to this effort, the company began to recover green areas and plant trees to pick up carbon dioxide emissions. To optimize the process, NHUMO also took into account legal requirements, environmental issues, technological operations, and operational requirements.

Projects put in place for each of the above strategies are described below.

Reduction of Fossil Fuel Consumption

NHUMO set up a strategic plan to avoid the use of fossil fuels (natural gas, settled oil, and electrical power) through the use of technology from a Cabot partner. The purpose of this plan is to minimize and prevent atmospheric pollution due to CO2 emissions.

Natural Gas

Each production unit had three Ashland technology reactors for the reaction process. The reactors at units I and II were replaced by Cabot reactors—specifically, an XF-70 reactor for each unit. This technology enabled each production unit to reduce natural gas consumption by 30%, by bringing in the heating potential of the high-temperature oil-air mixture. This is one of the few technologies that enables such levels. It is then injected into the reactors, thus optimizing natural gas use.

Another measure that optimized the use of this fossil fuel was enhanced service to the plant. This produced reductions in gas consumption of almost 47 million cubic meters. The strategy was implemented in 1993, and its results were clearly obvious after it was included in the EMS.

Settled Oil

Similar to the preceding case, consumption of settled oil decreased by 3% after the changeover to Cabot technology, resulting in a savings of more than 31 million kilograms from 1993 to 1997. Other strategies for increasing performance included negotiations with the Francisco I. Madero Refinery for improving the quality of settled oil (the main raw material), improving operating conditions on a continuous basis, and preheating the oil.

Electrical Power

NHUMO believes that efficient use of electrical power contributes significantly to reducing pollution. For this reason, the company undertook to incorporate high-efficiency motors into its operations, which increased the maintenance service factor from 72.7 to 86.6%. By replacing six Ashland reactors with two more efficient ones, NHUMO maximized production, decreased unit down time, and reduced process equipment. After this strategy was implemented, from 1993 through 1997, the decrease in energy consumption amounted to approximately 20 million kW/h. 

Replacement of Fossil Fuel Consumption by Process Energy

Recovery of Waste Gas for the Carbon Black Drying Process

Until 1993, all the waste gas from the carbon black process was released through stacks. Not only was the gas polluting the air, but the high residual heating potential that made the gas eligible as an alternative fuel was being wasted. In the drying process, 246 cubic meters of natural gas per ton of carbon black were consumed. Therefore, NHUMO made the effort to recover residual gas to re-use it as an energy source in the company's six dryers. This operation eliminated the use of natural gas and, as a result, almost completely eliminated emissions to the atmosphere. The result is that the company is reducing environmental pollution and contributing to the preservation of ecosystems.

Recovery of Residual Gas for the Steam Generation Process

Despite the fact that residual gas was being recovered during the carbon black drying process, combustion was still occurring in overhead burners. Then, in July of 1999, the company began using residual gas to generate steam—110,000 lb/h—both for its own use and in two neighboring plants. This project not only enables the utilization of residual gas, which used to be flared off, but eliminates the boilers in neighboring plants that formerly used natural gas. These measures contribute to the preservation of ecosystems.

CO2 Sequestration by Green Areas

Until 1990, most of the open areas at the plant were used for out-of-spec product storage or as dumping sites for trash, scrap metal, oil residue and sludge. In an intensive cleanup program, the company disposed of both hazardous and non-hazardous wastes properly. Most of the out-of-spec products, and waste in general, were recycled and re-used internally in the process, and were also sold outside as waste. Additionally, NHUMO removed all trash from nearby land and ponds, and sent oil residue and sludge to a confinement area. For restoration of damaged areas, a green area recovery program was implemented that involves preparing the soil in all appropriate areas, in order to plant ornamental foliage, fruit trees, and grass of all kinds. The result is remediation of these areas and sequestration of CO2. Currently 1,655 trees have been planted, in addition to green areas that include 40% of the total plant area.

ENVIRONMENTAL INDICATORS

To ensure environmental performance and the results of these ecoefficient strategies, NHUMO is using environmental performance indicators for water, air, and land. The status of each of these is monitored according to the requirements of the Norma Oficial Mexicana (Official Mexican Standard, or NOM) for the environment, and in some cases the company is more demanding:

Water. A monthly account is kept of the discharge conditions of wastewater under NOM-ECOL-001-1996; trend graphs are kept and analyses are made of potential situations for improvement.

Air. Stack-generated emissions are monitored every six months according to NOM-ECOL-043-1993 and NOM-ECOL-085-1993, and trends in emissions are analyzed for taking appropriate measures if the need arises to improve environmental performance in this area.

Land. Hazardous and non-hazardous wastes are evaluated and controlled to avoid any spills; final disposal is made in accordance with the NOM. Further monitoring of wastes with recycling potential is also occurring.

Results are communicated to staff on a monthly basis and included in the environmental performance report that is governed by the company's EMS procedures. For each indicator, there is a specified operational control for procedures in each area.

THE RESULTS AND THEIR EFFECT ON THE MITIGATION OF CO2

With respect to the environment, global ecoefficiency results have translated into a decrease of almost 450,000 tons in CO2 emissions during the 1993—97 period:

Variable / Element

Reduction

Avoided CO2 Emissions

Reduction

   

Natural Gas

112,080,000 m3

181,400 t

Settled Oil

82,300,000 kg

  29,700 t

Electric Power

38,600,000 kW/h

  6,300 t

Substitution

   

Natural Gas in Driers

103,000,000 m3

186,000 t

Natural Gas in Steam Generation*

38,825,196 m3

48,000 t

* Project in operation since July, 1999. The amounts represent one normal year of operation.

Pickup of 9.7 tons per year of CO2 should be added to the preceding, as a result of the green area program.

Projects for avoidance and replacement of fossil fuels have reduced CO2 emissions while at the same time achieving financial savings and making NHUMO a competitive company.

CONCLUSION

Before it achieved ISO 14001 certification, NHUMO had been working on a very aggressive process of change, with a focus on environmental conservation. The EMS implementation process confirmed this work in the area of conservation by systemizing the processes involved, providing stricter operational control of environmental issues and thus ensuring not only compliance with legal issues but maintenance of the environmental performance indicators that had been established by the system itself.

The company´s environmental performance since certification has been quite satisfactory. In May of 1999, the fourth follow-up audit was made, which showed zero recorded non-conformities. This is due in no small measure to operational controls and the visible results they have provided in three environmental areas—water, air, and land—for which NHUMO has a 100% legal compliance rate.

The actions begun in 1991 are the basis of the EMS, and they were already being implemented before certification was obtained. Among the goals is the need for ongoing work to develop projects that improve the company’s environmental performance.

Without a doubt, the fact that NHUMO has attained ISO 14001 certification has greatly impacted the carbon black market and also demonstrated the company’s strong commitment to the environment. For these reasons, it has become a competitiveness strategy for the company.

CONTACT

Ing. Mario A. Suro Rodríguez
General Director
Ing. Francisco MacSwiney S.
Operations Manager
NHUMO, S.A. de C.V.
Km 139.2 Carretera Mante-Tampico
Col. Laguna de la Puerta
89600 Altamira
Tamaulipas, Mexico
Tel. (52-12) 29 0500
Fax (52-12) 29 0565