PROCESS FOR THE REGULATION OF A PELLET PRESS

Abstract: When pressing a raw material, such as ground feedstuff, to pellets admission of steam to the material give rise to reduced crumbling of the pellets, reduced wear on the pellet press and reduced power consumption. The steam admission however may not be so great that the material stick to the press. For automatic regulation of the steam admission a plant is suggested in which the volume of steam is increased until the motor load of the press is no longer declining (point A), then maintained as long as the motor load is substantially unchanged (A-B) but reduced if the motor load rise drastically as a result of overloading (point B).

Description: PROCESS FOR THE REGULATION OF A PELLET PRESS. The invention relates to a process for the regulation of the temperature of a raw material, such as a ground feedstuff conducted to a pellet press, by proportional regulation of the volume of steam admitted to the raw material and the quantity of raw material supplied to the pellet press, by which said process a volume of steam . proportional to the quantity of the raw material after starting up is added, leaving the ratio mainly constant, after which the steam volume is increased proportionally to the quantity of raw material concerned. A process as the one described is known from the specificat¬ ions to Danish Patent no. 140.303, according to which • an increase of the volume of steam will proceed, until the motor load of the press begins to rise. An increase of the steam volume in the said manner will according to the patent specifications bring about an incipient gelatinization. It is accordingly by the known procedure necessary to reduce the volume of steam until the motor load drops to a minimum. The motor load will, however, immediately before the gelatinization occurs, remain constant over a relatively wide range of temperature. By the known process is thus merely achieved that the added volume of ste-am will not produce a gelatinization, but otherwise not that the steam volume is equal to optimum. The optimum steam volume is accordingly pursuant to the invention achieved in that the volume of steam is increased until the motor load of the press is no longer declining, after- which the temperature is retained irrespective of changing motor load, until the latter will rise drastically as a result of overloading. The described procedure will not bring about an incipient gelatinization through the regulation, but otherwise provide an optimum of added volume of steam of a measure that will exactly ensure the lowest possible motor The invention to be described in detail below with reference to the drawing in which Figure 1 shows schematically a pellet press regulated by means of the procedure according to the invention, and Figure 2 shows graphically the correlation between the motor load of the pellet press and the temperature. A pellet press can as shown by Figure 1 consist of a feed receptacle 1, a dosage worm conveyor 2 , a cascade mixer 5, a discharge funnel 6, and a pressroom 7 incorporating not shown press rollers and a matrix. From the pipe 9 steam can via the valves 10, 11 and 12 be conveyed into the cascade mixer 5, and in the discharge funnel 5 is inserted a temperature feeler 13. The raw material e.g. ground feedstuff is conveyed from the feed receptacle 1 to the cascade mixer 5 by means of the dosage worm conveyor 2, the speed of which is regulated in accordance with the desired load to the motor 8 of the press. Via a pilot valve 11 steam is likewise supplied to the cascade mixer 5 in a quantity determined by the temperature in the funnel 13. The steam-added feedstuff mixture is via the discharge funnel passed on to the pressroom 7, in which the feed mixture is pressed into pellets. By the supply of steam to a pellet press is achieved less crumbling of the finished product, less wear on matrice and rollers, and lower consumption of energy. In case of excessive steam supply, to such an extent that the feed mixture can not absorb all the steam, the mixture may stick to the press rollers with every possibility of blocking-up and resultant undesirable overloading of the press motor. The effect of the steam supply is illustrated in Figure 2, OM graphically showing the correlation between the electricity consumption of the motor 8 i.e. " the load on the press motor, and the temperature in the discharge funnel 6, being proportional to. the added volume of steam. As it appears from Figure 2 the current consumption of the motor will decrease in tact with the rising temperature until a certain temperature A has been reached. Up to this point it is possible to reduce the motor load by adding steam. When the temperature is further raised from A to B by adding an additional volume of steam, the current and the resultant load will remain practically unchanged. The volume of steam required to raise the temperature from A to B is accordingly wasted. When the temperature goes up further, the current consumption of the motor will rise drastically. The feed mixture is no longer capable of absorbing all the steam and will gelatinize and thereby block up the press rollers. By the process according to the invention the volume of steam will increase until the motor load stops falling (Stage A in Figure 2) . The steam volume has reached an optimum, as a further reduction of the motor load can not be obtained, and a further addition of steam will run to waste. OMPI

Claims: P A T E N T C L A I M Process for the regulation of the temperature of a raw material, such as a ground feedstuff conducted to a pellet press, by proportional regulation of the volume of steam admitted to the raw material and the quantity of raw material supplied to the pellet press, by which said process a volume of steam proportional to the quantity of raw material after starting is added, leaving the ratio mainly constant, after which the steam volume is increased proportionally to the quantity of raw material concerned, c h a r a c t e r i z e d i n t h a t the volume of steam is increased until the motor load of the press is no longer declining, after which the temperature is retained irrespective of changing motor load, until the latter will rise drastically as a result of overloading. OMPI

Inventors: SOE PEDERSEN A
Applicants: SOE PEDERSEN A
Application year: 1981
Main classification: A01F15
IPC codes: B30B11, B30B15