At present, many domestic producers of condensed milk, dry milk, dry whey and others. Condensed and powdered dairy products are forced to exploit vacuum evaporators and spray drying installations installed at enterprises in the 60s - 70s. Naturally, for such a long lifetime, equipment is worn out, morally obsolete, production losses increase, energy costs increase. In conditions of strong competition, and constantly rising energy prices, milk processing enterprises are in a difficult financial position.
The purchase of new equipment is one of the options for solving problems, but not every enterprise can afford it - the cost of equipment for the milk production plant for European production reaches several million euros. When the equipment is equipped with domestic equipment, the costs also amount to a million dollars.
An alternative solution to the problem is the modernization, restoration, reconstruction of evaporative and drying equipment. In this case, we propose ways to increase the efficiency of production of condensed and dried milk achieved at significantly lower costs, which pays off for 8 months of work.
For example, consider supply of energy carriers of equipment that is widely used in dairy plants: 2 vacuum evaporators "Vigant 4000" and a spray dryer A1-ОRCH. For heating the technological coolant in this equipment using overheated steam.
The total consumption of superheated steam equipment (according to passport standards) is 4 800 kg / h. To generate steam, a boiler house is operated, in which there are two or three steam boilers. Depending on the selected capacity of the boilers and the heat load of the process equipment, the amount of energy needed for the boiler-house operation:
- natural gas from 800 m³/h. up to 1200 m³/h;
- Electricity from 180 kW/h. up to 260 kW/h;
- Cold water per day from 60 m³ to 110 m³;
- softening reagents for water treatment;
- salary of operators and repairers for the maintenance of boiler equipment;
- maintenance and repair of the heating main of steam lines.
Our company offers a comprehensive energy-saving solution at dairy factories exploiting spray drying installations and vacuum evaporators operating on overheat steam. The essence of the proposal is as follows:
- transfer of heating of the coolant of the spray drying unit from the steam heater to the heat generator operating on natural gas and the translation of the coolant of the vacuum evaporator from the superheated steam to work on hot water, which is heated by a water-heating thermosiphon boiler.
- collection of condensate from a vacuum evaporator and further use it for washing process equipment.
The transfer of spray drying plants from work on steam heaters to the company's heat generators was carried out earlier, but only under certain conditions is the lack of superheated steam in this production, as a result, there was no necessary steam pressure on the calorifier, the coolant was not
heated, the drying plant lost its productivity, the cost of the powder increased, while working at low temperatures there was sticking wet powder, the service staff tapped the ducts and cyclones, damaged them.
Now the situation has fundamentally changed, the motivation for enterprises to transfer spray drying plant to the heat generator, is the economy. The application of the heat generator provides the following advantages:
- increasing the productivity of the spray dryer from the passport to 20%; as a result, the company obtains a low cost powder;
- reduction of energy consumption by natural gas and electricity per unit of finished product, which is not virtual, but real as a result of which the payback of invested capital funds takes place in 10 months;
- obtaining a stable coolant with a given temperature regime regardless of weather conditions, and the result is a good quality powder;
- Significant reduction of the influence of the human factor in the production of products;
- reduction of maintenance costs for heating mains - steam lines.
To date, the market offers heat generators of different manufacturers, the benefits of heat generators:
- The efficiency of the heat generator is 95%, which allows to be more economical in operation and spend less amount of natural gas;
- the design feature of the heat generator is such that the combustion chamber does not burn out at any operating load, it is cooled by flue gases which are released into the atmosphere;
- on a heat generator it is possible to use burners which work on different types of fuel: natural gas (methane), liquefied gas (propane-butane) or diesel fuel.
- Due to the design features of the burner, the flame is bulky and short, therefore the size of the combustion chamber is minimal, and hence the small dimensions of the heat generator and, as a consequence, the lower cost of the heat generator among the analogues;
- the automation of the heat generator provides the following functions:
• software ignition;
• positional (smooth) regulation of heat output (10-100%);
• shutdown of the burner: at the extinguishing of the flame, with the deviation of gas pressure from the norm in front of the burner, with the deviation of pressure in the combustion chamber from the nominal;
• light and sound alarm when deviating from the norm of controlled parameters;
• indication of the condition of sensors of controlled parameters.
Automation allows you to manage objects from the control point, and, as a means of controlling the state of the object, and direct control of the object. The control of the status of an object involves displaying information on the main parameters of the object (temperatures, pressures,
costs, heat of production, k.k.d. etc.), with the recording of these data in a journal with periodicity, which is established by the Customer, as well as with the possibility of forming time, daily and monthly reports.
In addition to the installed heat generator on the spray drying plant, our company proposes to install an additional heat-exchanger-recycler (recuperator), which allows the efficient use of heat coming into the atmosphere by utilizing the heat of waste gases.
The principle of this unit is as follows: the recuperator cuts into the exhaust pipe after the main exhaust fan, that is, through the primary circuit of the heat exchanger, the used air is drawn from the dryer with a temperature of 85-90 ° C and a volume of 25 thousand m³ per hour. And the output from the secondary circuit of the recuperator through the duct connects to the entrance to the heat generator. Thus, the clean cold air passing through the recuperator removes heat from the waste gases and heats up to 50 ºС, and then enters the heat generator.
The installed recuperator in front of the heat generator allows you to save up to 30% of the fuel to the heat generator. Heat utilizers work to increase the efficiency of the process unit by heating boiling air on the burners, or to solve the problem of obtaining coolant for external sources.
But unfortunately, even the positive experience gained in the use of spray drying plants for heat generators instead of steam heaters with excellent economic effect has not been properly disseminated among dairy enterprises. The reasons for this phenomenon are the following: after installing the heat generator, enterprises continue to operate steam boilers for the provision of superheated steam vapor-evaporators and other technological devices, and
so the cost of energy resources has usually dropped, but the main items of maintenance costs for the boiler house remained. Therefore, the engineers of our company developed a technology for the transfer of the main consumer of superheated steam with the condensation of milk - vacuum evaporator plants on the heat carrier - hot water, which is heated by a water-heated thermosyphon boiler.
A water boiler is installed next to a vacuum evaporator and pipelines loop the first stage of the apparatus with a water boiler. The temperature of the water entering the vacuum apparatus is 95 °C. In the system, a certain pressure is maintained. At the exit of a vacuum evaporator, the water temperature is 70-75 °C. Therefore, after reaching the required temperature technological regime, the water-heating boiler maintains a water temperature of 95 °C and works on heating the water to the delta at 20-25 °C.
Secondary steam is obtained in the second stage of the product and condensed in a condenser in water, which is collected in a container and used later for washing process equipment.
Currently, enterprises at the beginning of the boiler house conduct water preparation in front of steam boilers, then supply this water to the boiler and the received steam through the pipelines are fed into a vacuum evaporator, where in the first stage the steam is condensed and the condensate is merged into the sewer, the same is done with condensate water from the second degree. As a result: the enterprises carry out water treatment every day, they spend a huge amount of natural gas, electricity and labor resources for daily heating from 20 to 40 m³ of water and transfer it to steam-state. When transporting superheated steam on extended pipelines, they lose 1 to 3% of the thermal energy for every 100 running meters of the steam line, depending on the state of thermal insulation, etching and steam leakage. And as a rule, superheated steam from the boiler room to the technological equipment loses at a pressure of 1 to 2,5 atmospheres. And the steam generated with such expenses condenses into the water in technological equipment and merges into the sewage system in quantities of 40-80 m^3 every day. Based on the above, there is no doubt that the heating of water to the delta 25 ºС will be much more economical than heating the water to a vapor state, transporting steam to the technological equipment, and then condensing it into water.
The advantages of our power supply technology for vacuum evaporators with hot water are as follows:
- significant saving of energy resources of natural gas, electric energy, cold water;
- no noise when working with vacuum evaporator plants;
- soft technological regimes, in which the milk protein does not burn to the tubes and as a result of the absence of product losses;
- increasing the duration of the vacuum evaporator from the sink to the next washing;
- Improved installation sink, reduced washing time and volume of detergent solution.
At the same time, it should be noted and the lack of the proposed technology: it is a decrease in the productivity of vacuum evaporators from the passport of 15-20%, that is, the installation works with the same productivity, as the devices translated from the paronjectors to vacuum pumps.
One should especially stop at one moment, where enterprises lose significant energy - it is a sink of technological equipment.
With the proposed scheme of providing a vacuum evaporator with a coolant - hot water, the collection of condensed water is mandatory. From the apparatus "Vigant 4000" is collected from 15 to 20 m³ of condensed water per day, with a temperature of 60-75 ºC. The collected water is in two tanks with thermal insulation, for further use in washing and watering the water system with a water boiler.
The process of washing the vacuum apparatus with the help of detergents has several advantages:
- the washing takes 3-4 hours;
- during the washing process the following process equipment will not work: water boiler, cooling tower, rotary pumps;
- saving of cleansing solutions in 4 times (caustic and acid);
- saving water, with our technology of washing the equipment is 500-800 liters, with the traditional scheme of 5 tons.
Summing up, we can confidently assert that when installing all of the equipment we have listed above for obtaining the necessary heat resources to provide the above-mentioned technological equipment, direct costs will be:
- natural gas from 120 m³/h to 160 m³/h;
- Electricity from 24 kW/h to 30 kW/h;