Development and Design of Hazardous Waste Fuel Blending Facilities in Developing Countries
Gossman Consulting, Inc.
Gossman Consulting, Inc.
As developing countries move to greater awareness of environmental issues, the use of hazardous waste as fuel in cement kilns becomes an attractive option when compared with non-lined landfills and uncontrolled burning. When market and regulatory conditions are right, programs to use hazardous waste as fuel in cement kilns are being developed in ways analogous to the way the industry developed in the United States during the 1980's. Similar to that period of time in the U.S., program development standards for facility design and control are either non-existent or developing. Lessons learned in the U.S. and Europe can, and do, significantly enhance the development of these programs.
Developing countries are exhibiting more awareness of managing the wastes that increased economic activity generates. Some of this awareness is driven by the increasing affluence of their population seeking quality of life improvements, some is the result of the policies of the multinational corporations which frequently constitute the major industries in these countries. In other cases, it is driven by trade agreements. Several countries, often with grants from the United States or European countries, adopt regulations derived from USEPA or EU regulations on hazardous waste management. In any event, the proper management and disposal of hazardous wastes becomes a priority. Land disposal of such wastes comes under scrutiny, then is restricted and then banned.
This paper discusses the utilization of combustible materials in cement kilns as alternate fuels in developing countries. The development of this alternate fuels industry parallels its development in the United States in the 1970's and 1980's. There are of course differences. The level of sophistication is much higher and the learning curve is much steeper. Most of the pre-BIF and BIF requirements have been by-passed. The regulations resemble the hazardous waste combustion rule with truncated test requirements. There are other differences, frequently the result of the country's culture and how that culture is expressed in the bureaucracies of government and industry.
UNDERSTANDING THE MARKET
The first thing that must be done is to understand the market. What quantity and quality of waste is available for use as kiln fuel? Who generates the waste and where? This requires a local presence. An existing waste management company is the most logical choice. This company may have a business agreement with an international waste firm who will supply funds and management skills or may simply be an entrepreneur seeking to expand his business. There are advantages and disadvantages in utilizing an existing firm. Their existing contacts with the generators, particularly the multinationals, and the regulatory agency will be very important as will their knowledge of the market. The disadvantages are the existing baggage that the company may carry such as ongoing disagreements with the regulatory agency over past sins or a less than stellar business reputation. There is, however, no substitute for the contacts and knowledge of the market that an existing firm enjoys. A close second would be an aggressive local sales/marketing manager from a multinational petrochemical firm.
Next, it is necessary to educate the marketing people in what will and will not constitute acceptable alternate fuel. This may also require finding a laboratory that can perform certain analyses or more likely assembling the needed laboratory equipment and training the technicians. At this point, all that is necessary is a bomb calorimeter, a small centrifuge, some wet chemistry apparatus and sampling equipment and sample bottles.
Once a fair idea of the quantity and quality of the various liquid and solid alternate fuels is known, an analysis of the information can be made. The goal here is to determine the scope and size of the alternate fuels program. Is there enough fuel to support the program? Will the program utilize both liquids and solids or only one? In analyzing the marketing data, a few points should be kept in mind.
In the U.S., in the 1970's and 1980's, as the regulations tightened up, more wastes became available as fuel, much of it high quality with low solids. Then as the regulations tightened some more, the quantity decreased and the solids content increased. This will likely be the pattern in developing countries as well, however, the progression will be much more rapid. This must be kept in mind when examining the marketing data and in negotiating an alternate fuel specification with a cement kiln and in the design of the fuel blend/storage/utilization facilities. A cement kiln is sought once it is determined that there is sufficient volume on an ongoing basis to support a program and there is a fair knowledge about the quality of the fuel, particularly heat content, and chloride content.
Decidedly, liquid alternate fuels programs are less expensive and easier to set up and operate. Indeed, the first alternate fuels programs in the U.S. were liquids programs and many are exclusively liquids to this day. There are times however when a liquids only program is impractical. GCI once advised a client that there was insufficient liquid fuels to support a program which would be attractive to the cement kilns in the area. These kilns were large multi-stage preheaters and able to take only small amounts of chloride but with very large energy requirements. Since they were preheater kilns, they were able to easily utilize large volumes of solid wastes which there was an abundance of in the area. Unfortunately, the advise was not heeded. The program failed soon after it was completed.
SELECTING A CEMENT KILN
In some cases, selecting a cement kiln precedes the full scale marketing evaluation, particularly when there are large generators that must either find a suitable existing disposal method or build an incinerator. One instance in which GCI was involved, the generators formed a consortium to collect their waste and send it to a cement kiln as an alternative to having the government collect it and burn it in a purpose built incinerator. The program continues to this day.
When GCI evaluates cement kilns for the possible use of alternate fuels, this evaluation is strictly technical. Location with respect to the waste fuel facility is secondary. Generally, the cement kiln evaluation focuses on these points:
Based on the answers to these questions, an alternate fuel specification is formulated and an estimate made of the tonnage the kiln could consume annually.
MEETING THE REGULATORY REQUIREMENTS
As noted in the introduction, the regulatory requirements may be derived from USEPA or EU standards. In pursuing an operating permit, a three-way negotiation between the fuel supplier, the cement kiln, and the regulatory agency frequently develops. As a consultant to either the fuel supplier or the cement kiln, GCI often provides technical data or responses to technical questions posed by the regulatory agency. In the early stages, this generally consists of questions on destruction efficiencies and emission rates and requests for supporting data. As the negotiations continue, this evolves into specific questions on facility design and operating parameters.
Frequently, this is the first facility of its kind in this country, which is both good and bad. Good in that the facility will set the standard that all others must meet or exceed. Bad in that it is often a slow process as question and answers travel back and forth and both agency and industry deal with unfamiliar concepts and achieve a level of confidence and comfort with each other and the technology.
During this process, GCI often arranges visits to facilities in the United States for both kiln operations people and environmental agency representatives. This allows kiln operations people to see first hand the effect alternate fuels have on cement production and the agency representatives to observe alternate fuel management operations.
FACILITY DESIGN AND CONSTRUCTION
GCI frequently supplies facility process design specifications to our foreign clients; to the fuels supplier for the fuels blending facilities and to cement companies for the fuels utilization facilities. These process designs are not much different that those seen in the U.S. The fire prevention regulations are very similar to that in the U.S. regarding vapor control, tank spacing, mechanical design of tanks, tank containment and electrical requirements. In instances where the regulations are not as stringent as those in the U.S., the accepted U.S. design requirements are often utilized regardless to satisfy one or more of the major corporations involved (the international waste management firm, the international cement company or the multi-national firms which constitute the major generators.) The layout of the fuels blending facility generally follows the plan in Figure 1. It may be built in stages adding tanks and equipment as needed to keep pace with the growth of business. GCI generally recommends retaining a locally prominent engineering and construction firm to convert the process design into construction drawings and manage the construction. This provides the client with a number of advantages. The local firm will generally have good relations with the various regulatory agencies. They will also be familiar with the local code requirements. Most importantly, the local engineering firm will be familiar with the various equipment vendors, their product lines and service capabilities.
There are, however, disadvantages as well. Communication is impeded by language and cultural barriers. The equipment specified in the process design may not be sold or serviced by a firm in the country and the alternates recommended by the vendors may not be equal to the specified equipment. The local firm's engineers may not fully understand the reason for certain of the equipment specifications or why pipe lines are routed a certain way; this can lead to errors in construction.
Most of this can be overcome. The result may be a compromise from what would be built in the U.S., however, the client gains two long term advantages: 1) a local engineering firm which can provide them with ongoing service; and 2) equipment which is supported by local vendors.
Part of the facility design includes the laboratory. GCI provided clients with assistance in laboratory design, methods of analysis, quality assurance/quality control procedures, safety procedures, equipment selection, training, etc. As in the construction of the fuels blending facility, the use of a local firm is recommended to design and construct the building. A laboratory layout is provided and a specification of such things as chemical fume hoods, air conditioning loads, GC gas supply racks and supply line routing, etc. The analytical equipment is specified as well, preferably equipment which is sold and serviced by local vendors. In some cases, used equipment is available in the United States. This equipment is inspected and, if required, serviced and then sent to the laboratory.
The design and construction of the fuel utilization facility follows that of the fuels blending facility. The same engineering/construction firm designs the containment structure, fabricates the tank, purchases and installs the mixers, pumps, air compressor, pipe lines, etc., generally, to the same or similar specifications used in the blending facility.
The alternate fuel flow control system must be integrated into the kiln control system and the alternate fuel burner assembly designed to fit into the existing fossil fuel burner assembly. Here it is essential that a cement company engineer fully understands the alternate fuel control system requirements and the design of the burner assembly. Barriers to communication must be minimized in this area for the program to be successful.
TRAINING AND START-UP
The single greatest thing that can be done to train people in alternate fuel management is to provide them with a standard operating procedures manual in advance of the completion of the construction of the facility. This manual is a step-by-step description of the major procedures, from sampling an incoming waste truck to loading an outgoing fuel truck at the blending facility and from receipt to burning the fuel at the cement kiln. These descriptions should specify the safety gear required and precautions to be observed.
Even aside from any language barrier that may be present, providing this manual as soon as possible is an important step in establishing the proper attitude with respect to alternate fuels operation. This is true even though the manual will require revision later. First of all, the existence and content of the manual addresses three immediate concerns: 1) there is a definite plan and a set of procedures; 2) management of these wastes is a well understood practice; and 3) these procedures address the health and safety of the individual and protection of the environment.
Operations is the core of what most of the people in the facility do. Without a description of that which is going to be asked of them, i.e. a set of operating procedures, the training in such things as the use and care of personal protective equipment and the recognition of chemical hazards will appear less relevant and will be more frightening and confusing than it has to be. The manual will generate lots of questions. Most of these questions can be answered by facility supervisors. Some, however, will result in needed revisions. This is good for two reasons: 1) any errors should be found in advance of the facility starting up; and 2) the operations people will possess a sense of ownership of the procedures if they have an input in their development.
The ideal background for the development of a standard operation procedure manual is the completion of a hazardous operations study. A hazop study is a careful analysis of the process utilizing a list of keyword prompts to elicit a thorough investigation of what could go wrong with the equipment and what to do to mitigate or prevent the event. Operations, engineering and management participate in the study. The result is a set of recommendations addressing design inadequacies and procedures. Although the execution of a hazop can be tedious, it is very thorough and no one will feel that the SOP that resulted is inadequate. With the SOP manual in hand, it is relatively straight forward to train the people in the various procedures.
The start-up will probably be the single most stressful event in the entire process. A massive failure at this time, especially if a major spill or a fire ensues, will likely kill the program. On the other hand, making the start-up uneventful gives everyone confidence.
It is best to sit down and write out a plan: the sequence of equipment start-ups and what to look for as each piece is started or put on line. Stating what should happen as each of these pieces of equipment is put on-line will build the confidence of the operators.
This ability to describe what will happen is especially important when the fuel is fired into the kiln. Surprise and drama may make good theater, but it is not desired when combustible liquids are being injected into the burning zone of a kiln for the first time.
In one instance during a start-up nearly, all of the corporate officers were on hand to witness the start-up. The first try was aborted by an interrupt switch that had been set with too short of a time interval. Most of the officers wandered off, thinking there would be some delay. The switch was quickly reset at a longer interval. The alternate fuel flow was initiated and design rates achieved within approximately 30 minutes. None of the important operating parameters moved out of desired ranges. Upon being informed that the fuel was on and had been for 30 minutes, one of the returning corporate officers stated the whole thing was "anti-climatic."
The level of emissions testing required by the different countries is variable. Some require trace metals emissions determination, though the specific list of metals and allowable rates is highly variable, though few have required the spiking of metals as required be BIF. Some require dioxin/furan emission determination but do not have a specific standard which must be met. None require the kiln to be operated at "edge of the envelope" operating parameters as required by BIF.
Clearly, for the most part, the various developing countries have accepted the data generated from the tests conducted in the United States and Europe. Consequently, they do not feel the need to duplicate this work and are satisfied with tests that confirm the efficacy of the kiln system. As a result, they may only set two or three operating parameters.
Without a doubt, hazardous waste management programs in developing countries are accelerated by the waste management technology developed in the United States and Europe. However, the utilization of combustible wastes as fuel in cement kilns has not progressed as quickly as one would expect. This can be attributed to a number of reasons. Regulations banning land disposal of these wastes have been implemented more slowly than expected. In developing countries, the cement kilns tend to be new and large, or old and small. If new, these kilns frequently have limitations on chloride input which limits their usefulness. Additionally, large kiln systems have huge energy demands and a developing country may not have sufficient waste fuels to support a program attractive to such users, particularly during the first two or three years. If there are only older and smaller kilns, the kiln system may require improvements to obtain a permit or the management of the kiln may be hesitant to achieve the higher energy substitution rates needed to satisfy the fuels blending company.
Frequently, there is a bias within the local environmental groups
against the use of cement kilns. In some cases, this is evident in the
environmental agency personnel as well. This retards the acceptance of
cement kilns as users of alternate fuels.
However, the record and experiences in the United States and Europe are a very persuasive argument that this is a safe and effective technology. Being able to use these experiences to shortcut the developmental curve is attractive as well. Nothing sells as well as success, particularly when the road to that success is so well mapped out.