阅读说明：本技术 一种硝酸钾生产用自控蒸馏水器及蒸馏方法 (Automatic control water distiller for potassium nitrate production and distillation method ) 是由 常先进 于 2021-10-08 设计创作，主要内容包括：本发明公开一种硝酸钾生产用自控蒸馏水器及蒸馏方法,涉及自控蒸馏水器相关技术领域,包括桶状结构的物料桶,物料桶的内壁设置有隔板,隔板的侧壁贯通开设有通孔,物料桶顶端处的外壁连接有导管,导管缠绕在物料桶的外壁,导管的外壁套接有散热块,导管的端部固定有导料罩,物料桶的外壁固定有水道,导料罩的端部与水道远离开口端的内壁齐平,导管与物料桶之间通过陶瓷隔热板隔离,导管外壁的散热块设置有多个,通孔的直径较大的一端朝向物料桶的内部,通孔在隔板的侧壁呈阵列分布,通孔的中心轴与隔板的中心轴所在方向齐平。通过以上各装置的配合使用,能够提升水蒸汽凝结的速率,并且能够使水蒸气凝结的速率保持稳定,提升水蒸汽凝结的量。(The invention discloses an automatic control water distiller for potassium nitrate production and a distillation method, and relates to the related technical field of automatic control water distiller. Through the cooperation of above each device use, can promote the rate that steam condenses to can make the rate that steam condenses remain stable, promote the volume that steam condenses.)

1. The utility model provides a potassium nitrate production is with automatic control distiller, includes material bucket (1) of tubbiness structure, the inner wall of material bucket (1) is provided with baffle (2), its characterized in that: the side wall of the partition plate (2) is provided with a through hole (3) in a penetrating manner, the outer wall of the top end of the material barrel (1) is connected with a guide pipe (4), the guide pipe (4) is wound on the outer wall of the material barrel (1), the outer wall of the guide pipe (4) is sleeved with a radiating block (5), and the end part of the guide pipe (4) is fixed with a guide cover (6);

the material barrel is characterized in that a water channel (7) is fixed on the outer wall of the material barrel (1), the end part of the material guide cover (6) is flush with the inner wall, far away from the opening end, of the water channel (7), the guide pipe (4) is isolated from the material barrel (1) through a ceramic heat insulation plate, a plurality of heat dissipation blocks (5) are arranged on the outer wall of the guide pipe (4), and the heat dissipation blocks (5) are distributed on the outer wall of the guide pipe (4) at equal intervals.

2. The automatic control water distiller for potassium nitrate production of claim 1 is characterized in that: the plane of baffle (2) place flushes with the bottom side of material bucket (1), through-hole (3) are horn type structure, and the great one end of diameter of through-hole (3) is towards the inside of material bucket (1), and is a plurality of through-hole (3) are array distribution at the lateral wall of baffle (2), the center pin of through-hole (3) flushes with the center pin place direction of baffle (2), the edge of through-hole (3) tip is the arc structure, and the edge of the great one end of through-hole (3) bore flushes with the side of baffle (2).

3. The automatic control water distiller for potassium nitrate production of claim 1 is characterized in that: pipe (4) are provided with two, and two bottom department and top department that material bucket (1) space was cut apart in baffle (2) are located respectively in pipe (4) two the winding opposite direction of pipe (4) at material bucket (1) outer wall, two the one end that material bucket (1) was kept away from in pipe (4) assembles, and guide cover (6) link up with the department of assembling of pipe (4) tip, the outer wall an organic whole of pipe (4) is provided with vice branch (41), the both ends of vice branch (41) link up with the inside of material bucket (1) and the inside of pipe (4) respectively.

4. The automatic control water distiller for potassium nitrate production of claim 1 is characterized in that: the heat dissipation structure is characterized in that heat exchange tubes (51) are fixed to the side faces, far away from the heat dissipation block (5), of the heat dissipation block (5) in bilateral symmetry, curved tubes (52) are arranged between the heat exchange tubes (51), the curved tubes (52) are of wave-shaped structures, heat exchange agents are filled in the heat exchange tubes (51), a plurality of heat dissipation fins (53) are fixed to the outer walls of the curved tubes (52), the heat dissipation fins (53) are arranged in two groups, and air guide fans (54) are installed between the two groups of heat dissipation fins (53).

5. The automatic control water distiller for potassium nitrate production of claim 4 is characterized in that: the air-conditioner is characterized in that a containing cavity (55) is arranged at the joint of the curved pipe (52) and the radiating fins (53), a plurality of auxiliary fins (56) are integrally arranged on the outer wall of the containing cavity (55), the auxiliary fins (56) are distributed on the outer wall of the containing cavity (55) in an annular and equidistant mode, the containing cavity (55) is of a hollow spherical structure, and the plane where the radiating fins (53) are located is flush with the wind direction of the air guide fan (54).

6. The automatic control water distiller for potassium nitrate production of claim 2 is characterized in that: the outer wall of the smaller one end of through-hole (3) bore an organic whole is provided with baffle (31), perforation (32) have been seted up to the lateral wall of through-hole (3) near baffle (31) department, the opening direction of perforation (32) is just right with the side of baffle (31), and the one end of keeping away from through-hole (3) tip of baffle (31) is skew horizontal direction 30-60 downwards, baffle (2) are middle part bellied thin shell type structure, and pipe (4) stretch into the lateral wall of the inside one end of material bucket (1) and the top surface laminating of baffle (2).

7. The automatic control water distiller for potassium nitrate production of claim 1 is characterized in that: the utility model discloses a guide device, including guide cover (6), flexible pipe (61), gasbag (62) that guide cover (6) kept away from pipe (4) one end is fixed with ring type structure, the bottom side of gasbag (62) flushes with the bottom of guide cover (6), flexible pipe (61) cup joint the outer wall of pipe (4), and junction between them is provided with ball (63), the outer wall cover of ball (63) has the inner wall of flexible pipe (61) and the outer wall laminating of pipe (4).

8. The automatic control water distiller for potassium nitrate production of claim 4 is characterized in that: one side of heat radiation fin (53) is fixed with thermal-arrest piece (57), one side that heat arrest piece (57) is far away from heat radiation fin (53) is fixed with thermoelectric refrigeration piece, the heat dissipation end of thermoelectric refrigeration piece is connected with heat dissipation fan (58), heat dissipation fan (58) are connected with logic controller, the side-mounting of heat radiation fin (53) has temperature sensor, temperature sensor's output and logic controller's input are connected.

9. The automatic control water distiller for potassium nitrate production and the distillation method adopt the automatic control water distiller for potassium nitrate production as claimed in claim 1, and is characterized by comprising the following steps:

t1, water in the material barrel (1) is heated and evaporated, water vapor passes through the through hole (3) and is gathered in a space above the partition plate (2) of the material barrel (1), the water vapor flows towards the direction of the material guide cover (6) through the guide pipe (4) along with the rise of air pressure, and the heat dissipation block (5) exchanges heat between air and the guide pipe (4) to enable the water vapor to be condensed and finally collected by the water channel (7);

t2, heat radiation fins (53) increase the heat radiating area of radiating block (5), and then promote heat exchange efficiency, can promote the rate that steam condenses to increase the volume that steam condenses, and guide cover (6) and the inside distilled water contact of water course (7), make not can liquefy in the distilled water at the inside liquefied steam of pipe (4), thereby make the preparation of distilled water high-efficient more.

Technical Field

The invention relates to the technical field of self-control water distiller correlation, in particular to a self-control water distiller for potassium nitrate production and a distillation method.

Background

In the production process of potassium nitrate, in order to prevent the product from being mixed with other impurities to influence the purity, a solvent in the production process mainly adopts distilled water, the preparation of the distilled water is greatly the same as and different from each other, taking the existing water distiller commonly used for the preparation of potassium nitrate as an example, water is heated, the water distillation is realized by utilizing the principle that water vapor meets condensation, but the ambient environment can be increased along with the proceeding of the water vapor heat exchange process, so that the efficiency of water vapor condensation is gradually reduced, even the normal condensation of the water vapor can be influenced, the normal production of the potassium nitrate is influenced, and when the supply of the distilled water is insufficient, certain potential safety hazards are extremely easily generated, therefore, the self-control water distiller for producing the potassium nitrate can ensure the preparation efficiency of the distilled water, and the distilled water used in the preparation process of the potassium nitrate can not be in shortage condition, to solve the above problems.

Disclosure of Invention

The invention aims to provide a self-control water distiller for potassium nitrate production and a distillation method, which aim to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: the utility model provides a potassium nitrate production is with automatic control distiller, includes the material bucket of tubbiness structure, and the inner wall of material bucket is provided with the baffle, and the through-hole has been seted up in the lateral wall link up of baffle, and the outer wall connection of material bucket top department has the pipe, and the pipe winding is at the outer wall of material bucket, and the radiating block has been cup jointed to the outer wall of pipe, and the end fixing of pipe has the guide cover, prevents the steam loss, guarantees the output of distilled water.

The outer wall of material bucket is fixed with the water course, and the tip of guide cover flushes with the inner wall that the open end was kept away from to the water course, keeps apart through ceramic heat insulating board between pipe and the material bucket, and the radiating block of pipe outer wall is provided with a plurality ofly, and a plurality of radiating blocks are distributed at the outer wall equidistance of pipe, can promote the radiating rate between pipe and the air.

In further embodiment, the plane that the baffle is located flushes with the bottom side of material bucket, and the through-hole is horn type structure, and the great one end of diameter of through-hole is towards the inside of material bucket, and a plurality of through-holes are array distribution at the lateral wall of baffle, and the center pin of through-hole flushes with the center pin place direction of baffle, and the edge of through-hole tip is the arc structure, and the edge of the great one end of through-hole bore flushes with the side of baffle, can increase the flow rate of steam in the pipe is inside.

In further embodiment, the pipe is provided with two, and two pipes are located the bottom department and the top department that the material bucket space was cut apart to the baffle respectively, two pipes are opposite at the winding direction of material bucket outer wall, the one end that the material bucket was kept away from to two pipes assembles, and the guide cover link up with the department of assembling of pipe end portion, the outer wall an organic whole of pipe is provided with vice branch, the both ends of vice branch link up with the inside of material bucket and the inside of pipe respectively, can increase the inside circulation of steam guide pipe, and then promote the speed of steam circulation.

In a further embodiment, heat exchange tubes are fixed on the far side surfaces of the radiating blocks, bent tubes are arranged between the heat exchange tubes symmetrically arranged on two sides of the radiating blocks, the bent tubes are of a wave-shaped structure, a heat exchange agent is filled in the heat exchange tubes, a plurality of radiating fins are fixed on the outer walls of the bent tubes, two groups of radiating fins are arranged, and air guide fans are arranged between the two groups of radiating fins, so that the air flow rate is increased, and the rate of water vapor heat exchange condensation can be increased.

In a further embodiment, a containing cavity is formed in the joint of the curved pipe and the radiating fins, a plurality of auxiliary fins are integrally arranged on the outer wall of the containing cavity, the auxiliary fins are distributed on the outer wall of the containing cavity in an annular and equidistant mode, the containing cavity is of a hollow spherical structure, and the plane where the radiating fins are located is flush with the wind direction of the wind guide fan, so that deformation of the curved pipe caused by air pressure change is prevented.

In further embodiment, the baffle is provided with in an organic whole of the outer wall of the less one end of through-hole bore, the lateral wall of through-hole has been seted up the perforation near baffle department, the side of fenestrate opening direction and baffle is just right, and the one end of keeping away from the through-hole tip of baffle is the skew horizontal direction 30-60 downwards, the baffle is middle part bellied shell type structure, and the pipe stretches into the lateral wall of the inside one end of material bucket and the top surface laminating of baffle, helps promoting the volume that the steam condenses, and then promotes the output of distilled water.

In further embodiment, the guide cover is connected with the end of the guide pipe through a telescopic pipe, the outer wall of one end, away from the guide pipe, of the guide cover is fixed with an air bag of a circular ring type structure, the bottom side of the air bag is flush with the bottom end of the guide cover, the telescopic pipe is sleeved on the outer wall of the guide pipe, balls are arranged at the joint of the telescopic pipe and the guide pipe, the outer wall of each ball is sleeved with the inner wall of the telescopic pipe and the outer wall of the guide pipe to be attached, the guide cover can float on the water surface, and the backflow of distilled water can be effectively prevented.

In a further embodiment, a heat collecting block is fixed on one side of each heat radiating fin, a thermoelectric refrigerating sheet is fixed on one side, away from the heat radiating fins, of each heat collecting block, a heat radiating fan is connected to the heat radiating end of each thermoelectric refrigerating sheet, each heat radiating fan is connected with a logic controller, a temperature sensor is installed on the side surface of each heat radiating fin, the output end of each temperature sensor is connected with the input end of each logic controller, and the temperature of each heat radiating fin can be regulated and controlled, so that the temperature of each heat radiating fin can be stably maintained, and the liquefaction rate of water vapor is improved.

A self-control water distiller for potassium nitrate production and a distillation method thereof specifically comprise the following steps:

t1, water in the material barrel is heated and evaporated, water vapor passes through the through hole and is gathered in a space above the partition plate of the material barrel, the water vapor flows towards the direction of the material guide cover through the guide pipe along with the rise of air pressure, and the heat dissipation block exchanges heat between air and the guide pipe, so that the water vapor is condensed and is finally collected by the water channel;

t2, heat radiation fins increase the heat radiating area of radiating block, and then promote heat exchange efficiency, can promote the rate that steam condenses to increase the volume that steam condenses, and the guide cover contacts with the inside distilled water of water course, make not can liquefy in the distilled water at the inside liquefied steam of pipe, thereby make the preparation of distilled water high-efficient pureness more.

Compared with the prior art, the invention has the beneficial effects that:

the invention discloses a self-control water distiller for potassium nitrate production and a distillation method, wherein the heat exchange area of water vapor can be increased through a guide pipe and heat dissipation fins, the flow rate and the air flow rate of air among the heat dissipation fins can be increased through a heat dissipation fan, the heat accumulation of the heat dissipation fins and the guide pipe can be further prevented, so that the stable heat exchange of the water vapor is ensured, and a guide cover can float above the liquid level in a water channel by utilizing an air bag on the outer wall of the guide cover, so that the backflow of distilled water in the water channel can be effectively prevented, and the yield of the distilled water is ensured.

The thermoelectric refrigerating sheet can further reduce the temperature of the radiating fins, thereby increasing the temperature difference between the water vapor and the guide pipe and between the water vapor and the radiating fins, improving the condensation rate of the water vapor and increasing the yield of distilled water.

Drawings

FIG. 1 is a schematic diagram of a material barrel according to an embodiment of the present invention;

FIG. 2 is a partial cross-sectional view of a material bucket according to an embodiment of the present invention;

FIG. 3 is an enlarged view of the structure at A in FIG. 2 according to an embodiment of the present invention;

FIG. 4 is a structural view of a heat exchange tube according to an embodiment of the present invention;

FIG. 5 is a structural view of a heat exchange tube in example 2 of the present invention;

fig. 6 is a structure view of a telescopic tube in embodiment 3 of the present invention.

In the figure: 1. a material barrel; 2. a partition plate; 3. a through hole; 31. a baffle plate; 32. perforating; 4. a conduit; 41. a subsidiary branch; 5. a heat dissipating block; 51. a heat exchange pipe; 52. a curved pipe; 53. heat dissipation fins; 54. a wind guide fan; 55. a cavity; 56. a secondary fin; 57. a heat collection block; 58. a heat dissipation fan; 6. a material guiding cover; 61. a telescopic pipe; 62. an air bag; 63. a ball bearing; 7. a water channel.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

Example 1

Referring to fig. 1-4, the embodiment provides a self-control water distiller for potassium nitrate production, which includes a material barrel 1 with a barrel-shaped structure, wherein the material barrel 1 is of a cylindrical structure, and the top end of the material barrel is of an arc-shaped structure, so that the material barrel can be effectively prevented from bursting or deforming in the process of water heating and evaporation, and the problem that the tightness of the material barrel 1 is damaged due to air pressure change can be avoided.

Wherein, the inner wall of material bucket 1 is provided with baffle 2, the lateral wall of baffle 2 link up and has seted up through-hole 3, the outer wall connection of 1 top department of material bucket has pipe 4, pipe 4 winding is at the outer wall of material bucket 1, the radiating block 5 has been cup jointed to the outer wall of pipe 4, the end fixing of pipe 4 has guide cover 6, steam passes through-hole 3 and is transmitting via pipe 4, rethread radiating block 5 increases heat exchange efficiency, finally condense the back through guide cover 6 discharges.

The outer wall of the material barrel 1 is fixed with a water channel 7, the end part of the material guide cover 6 is flush with the inner wall of the water channel 7 far away from the opening end, the guide pipe 4 is isolated from the material barrel 1 through a ceramic heat insulation plate, and the influence of the temperature of the material barrel 1 on the condensation process of water vapor can be reduced.

In order to promote the heat exchange rate of steam, the radiating block 5 of pipe 4 outer wall is provided with a plurality ofly, and a plurality of radiating blocks 5 distribute at the outer wall equidistance of pipe 4, and the cooperation of a plurality of radiating blocks 5 is used, can further increase the area of contact between pipe 4 and the air, promotes the heat exchange rate between pipe 4 and the air to promote steam heat exchange rate.

In order to increase the flow velocity of the gas inside the conduit 4, the plane of the partition board 2 is flush with the bottom side of the material barrel 1, the through hole 3 is of a horn-shaped structure, the larger diameter end of the through hole 3 faces the inside of the material barrel 1, the plurality of through holes 3 are distributed in an array mode on the side wall of the partition board 2, the center shaft of the through hole 3 is flush with the direction of the center shaft of the partition board 2, the edge of the end part of the through hole 3 is of an arc-shaped structure, the edge of the larger caliber end of the through hole 3 is flush with the side face of the partition board 2, the horn-shaped structure can increase the flow velocity of the water vapor, further, the Bernoulli principle can be utilized, condensation of the water vapor on the inner wall of the material barrel 1 is realized, and along with the increase of the flow velocity of the water vapor, the change rate of the internal air pressure of the material barrel 1 can be correspondingly increased, the flow velocity of the water vapor inside the conduit 4 can be increased, and the rate of heat exchange of the water vapor discharge is increased.

Wherein, pipe 4 is provided with two, and two pipe 4 are located the bottom department and the top department that baffle 2 cut apart 1 space of material bucket respectively, and two pipe 4 are opposite at the winding direction of 1 outer wall of material bucket, and the one end that material bucket 1 was kept away from to two pipe 4 assembles, and the guide cover 6 link up with the department of assembling of pipe 4 tip, can arrange outside fast the steam of 1 top departments of material bucket, can also arrange outside the steam that has condensed of 2 side departments of baffle.

Preferably, the outer wall of the conduit 4 is integrally provided with an auxiliary branch 41, and two ends of the auxiliary branch 41 are respectively communicated with the inside of the material barrel 1 and the inside of the conduit 4, so as to further increase the speed at which the water vapor in the material barrel 1 is not transferred to the conduit 4.

In order to improve the heat exchange rate of the water vapor, the heat exchange tubes 51 are fixed on the side surfaces of the radiating block 5 far away from each other, the curved tubes 52 are arranged between the heat exchange tubes 51 symmetrical to the two sides of the radiating block 5, the curved tubes 52 are of wave-shaped structures, the contact area between the curved tubes 52 and the radiating fins 53 can be increased, the water vapor heat exchange time is prolonged, the water vapor heat exchange effect is improved, and the condensation is facilitated.

Preferably, a heat exchange agent is filled in the heat exchange tube 51, a plurality of heat dissipation fins 53 are fixed on the outer wall of the curved tube 52, two groups of heat dissipation fins 53 are arranged, an air guide fan 54 is installed between the two groups of heat dissipation fins 53, the heat exchange agent absorbs heat and vaporizes, the air flow rate is increased by the air guide fan 54 to carry out heat exchange, the heat exchange agent can be changed into a liquid state again, and the heat exchange rate of the steam can be effectively increased through cyclic reciprocation.

And, the heat exchange agent fills the inside of the heat exchange tube 51, and the amount of heat carried by the heat exchange tube 51 in unit time can be correspondingly increased, thereby improving the heat exchange efficiency of the water vapor.

Example 2

Referring to fig. 5, a further improvement is made on the basis of embodiment 1: generally, the contact surface between the curved tube 52 and the heat dissipation fins 53 is small, so that there is a certain limit to the heat transfer between the two, and simply changing the material will increase the amount of precious metal used, and increase the cost.

In order to further improve the heat transfer rate between the curved tube 52 and the heat dissipation fins 53, a cavity 55 is arranged at the joint of the curved tube 52 and the heat dissipation fins 53, a plurality of secondary fins 56 are integrally arranged on the outer wall of the cavity 55, the plurality of secondary fins 56 are annularly and equidistantly distributed on the outer wall of the cavity 55, and the secondary fins 56 can increase the contact area between the curved tube 52 and the heat dissipation fins 53, so that the heat transfer rate between the curved tube 52 and the heat dissipation fins 53 can be improved.

Preferably, the cavity 55 is a hollow spherical structure, the plane where the heat dissipation fins 53 are located is flush with the wind direction of the air guiding fan 54, the cavity 55 with the spherical structure can effectively contain the vaporized heat transfer agent well, the situation that the curved tube 52 is broken can be effectively prevented, the wind direction is flush with the heat dissipation fins 53, and air can flow more smoothly between the heat dissipation fins 53.

In order to further promote the liquefied rate of water vapor, the less outer wall an organic whole of one end of 3 bores of through-hole is provided with baffle 31, the lateral wall of through-hole 3 is close to baffle 31 department and has seted up perforation 32, perforation 32's opening direction is just right with the side of baffle 31, baffle 2 is the bellied shell type structure in middle part, and pipe 4 stretches into the lateral wall of 1 inside one end of material bucket and the laminating of the top surface of baffle 2, water vapor hits the side of beating at baffle 31, can carry out the transfer in the energy, and then can make the water vapor liquefaction of partly clashing with baffle 31, and then can increase the liquefied volume of water vapor.

One end of the baffle plate 31 far away from the end part of the through hole 3 is downwards deviated from the horizontal direction by 30-60 degrees, so that the water vapor which collides with the baffle plate 31 but is not liquefied can be contacted with the residual distilled water on the surface of the partition plate 2, and the amount of the water vapor which is liquefied into the distilled water is increased.

Example 3

Referring to fig. 6, a further improvement is made on the basis of embodiment 2: in order to prevent the steam from dissipating during the guiding, the output port of the steam is mostly in direct contact with the liquid level, and after the water distillation is finished, the distilled water flows back along the guide pipe 4 due to the change of the air pressure in the material barrel 1.

In order to prevent the material guide cover 6 from extending below the liquid level, the material guide cover 6 is connected with the end of the guide tube 4 through a telescopic tube 61, an air bag 62 with a circular ring structure is fixed on the outer wall of one end, away from the guide tube 4, of the material guide cover 6, the bottom side of the air bag 62 is flush with the bottom end of the material guide cover 6, the telescopic tube 61 is sleeved on the outer wall of the guide tube 4, a ball 63 is arranged at the joint of the telescopic tube and the air bag, and the outer wall of the ball 63 is sleeved with the inner wall of the telescopic tube 61 and the outer wall of the guide tube 4 for fitting.

The material guiding cover 6 can float on the liquid level under the action of the air bag 62, and when the air pressure in the material feeding device 1 is reduced and the distilled water has the tendency of counter flow, the counter flow water can cause the reduction of the liquid level, so that the situation that the distilled water continuously flows back can not occur.

In order to further increase the rate of heat exchange and condensation of water vapor, a heat collection block 57 is fixed on one side of the heat dissipation fins 53, a thermoelectric refrigeration sheet is fixed on one side of the heat collection block 57 away from the heat dissipation fins 53, a heat dissipation fan 58 is connected to a heat dissipation end of the thermoelectric refrigeration sheet, the heat dissipation fan 58 is connected to a logic controller, a temperature sensor is installed on a side surface of the heat dissipation fins 53, and an output end of the temperature sensor is connected to an input end of the logic controller.

The temperature sensor can monitor the temperature of the heat dissipation fins 53 in real time, so that the thermoelectric refrigeration piece can adjust the power of the thermoelectric refrigeration piece, the heat dissipation fins 53 can keep a lower temperature, and the liquefaction rate of water vapor can be ensured.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.