JP4904646B2

JP4904646B2 - Refrigeration system

Info

Publication number: JP4904646B2
Application number: JP2001249446A
Authority: JP
Inventors: 繁則松本; 信吾高雄; 英雅生越
Original assignee: JFE Engineering Corp
Current assignee: JFE Engineering Corp
Priority date: 2001-08-20
Filing date: 2001-08-20
Publication date: 2012-03-28
Anticipated expiration: 2021-08-20
Also published as: JP2003055650A

Description

【０００１】
【発明の属する技術分野】
本発明は、水和物スラリを冷熱輸送媒体として利用する冷熱利用システムに関する。
【０００２】
【従来の技術】
冷房や産業用の冷熱利用システムの分野において、冷熱媒体の輸送熱密度を増大させることにより、流送量を減少させ、輸送ポンプ動力の低減、輸送配管の小口径化を図り、配管コスト・工事費を低減することが試みられている。冷熱媒体の輸送熱密度を増大させる手段として、顕熱に加えて固液相変化時の潜熱を利用する冷熱輸送媒体を用いる技術が知られている。たとえば現在、水の顕熱と氷の融解潜熱を利用する氷水スラリが、高い熱密度を持つ冷熱輸送媒体として試みられている。
【０００３】
冷房や産業用の冷熱利用システムに、顕熱と潜熱を利用でき高い熱密度を持つ冷熱輸送媒体を用いる場合、冷熱負荷に見合った冷熱量で冷熱輸送媒体を供給することが望まれる。その手段として、氷水スラリを冷熱輸送媒体とする場合に、輸送冷熱量を低くするには、冷凍機の能力を制御して部分負荷運転とし、氷水スラリ中の氷の割合を低下させて冷熱の輸送熱密度を小さくする方法が考えられている。
【０００４】
しかし、氷のように相変化時の温度が一定である冷熱輸送媒体を用いる場合、冷凍機の部分負荷運転時においても冷凍機を構成する蒸発器の冷媒蒸発温度は一定のままに維持する必要がある。このため、蒸発器の冷媒蒸発温度を上げて冷凍機の成績係数（ＣＯＰ）を向上させるという運転方法を採用することができず、部分負荷運転に起因するＣＯＰの低下が生じるだけである。
【０００５】
【発明が解決しようとする課題】
本発明の目的は、顕熱と潜熱を利用でき高い熱密度を持つ冷熱輸送媒体として水和物スラリを用い、その水和物スラリを製造するための冷凍機の成績係数を向上できる冷熱利用システムを提供することにある。
【０００６】
【課題を解決するための手段】
本発明に係る冷熱利用システムは、水和物を生成するゲスト化合物の水溶液を冷却して水和物スラリを製造する冷凍機と、前記冷凍機と冷熱を利用する負荷側機器とを連通する配管系とを有する冷熱利用システムであって、前記冷凍機から負荷側機器への配管に設けられた第１の熱密度計と、負荷側機器から前記冷凍機への配管に設けられた第２の熱密度計と、前記第１および第２の熱密度計から得られる水和物スラリの熱密度の差から冷熱負荷を計測し、前記冷熱負荷に応じて水和物スラリの熱密度を変化させて製造するように冷凍機の運転を制御する装置とを具備したことを特徴とする。
【０００７】
一つの態様において、上記冷熱利用システムは、前記第１および第２の熱密度計のそれぞれが、水和物スラリの固相率が変化した場合に流量指示値が連動して変化する第１の流量計と、水和物スラリの固相率が変化しても流量指示値が変化しない第２の流量計と、水和物スラリの温度を測定する温度計と、前記第１および第２の流量計のそれぞれからの実測流量指示値および前記温度計により計測された温度に基づいて、水和物スラリの熱密度を算出する演算器とを具備することを特徴とする。
【０００８】
他の態様において、上記冷熱利用システムは、前記第１および第２の熱密度計のそれぞれが、オリフィスおよび該オリフィスの上流側に備えられた第１の圧力計および該オリフィスの下流側に備えられた第２の圧力計を具備する圧損測定部と、前記圧損測定部の上流側に設けられた、水和物スラリの流量を測定する流量計および水和物スラリの温度を測定する温度計と、前記第１および第２の圧力計、前記流量計および前記温度計からの計測値に基づいて、水和物スラリの熱密度を算出する演算器とを具備することを特徴とする。
【０００９】
上記の冷熱利用システムにおける冷凍機の運転を制御する装置は、たとえば冷凍機を構成する蒸発器の冷媒蒸発温度を制御する装置を備えている。
【００１０】
【発明の実施の形態】
以下、本発明をより詳細に説明する。
テトラｎ−ブチルアンモニウム塩、テトラｉｓｏ−アミルアンモニウム塩、テトラｉｓｏ−ブチルホスホニウム塩、トリｉｓｏ−アミルスルホニウム塩などのゲスト化合物の水溶液を冷却すると、０℃以上の温度でゲスト化合物の水和物が生成し、水溶液中に水和物が分散した水和物スラリとなる。このような水和物スラリは、ゲスト化合物が溶解した水溶液から冷却によって水和物の固体が生成する固液相変化時に潜熱を持つため高い熱密度を持つ冷熱輸送媒体として利用できる。
【００１１】
図１に、水和物スラリの代表例として、テトラｎ−ブチルアンモニウムブロマイド（ＴＢＡＢ）水和物スラリについて、スラリ温度１２℃を基準とした温度と比エンタルピとの関係を示す。この図に示されるように、水和物スラリはある温度域で潜熱を持つという特徴を有する。すなわち、水和物スラリの温度が高いと熱密度が小さく、水和物スラリの温度が低いと熱密度が大きい。このため、冷熱利用システムの冷熱輸送媒体として水和物スラリを用いる場合、負荷側機器の冷熱負荷が小さいときには、潜熱を利用できる範囲で水和物スラリの温度を高くすることにより熱密度を小さくすることが可能である。このことは、冷熱負荷が小さいときには、水和物スラリの温度を上げるように、たとえばゲスト化合物の水溶液を冷却する冷凍機の蒸発器の冷媒蒸発温度を上げて運転できることを意味する。
【００１２】
したがって、冷熱負荷が小さいときには、冷熱負荷に応じて小さな熱密度を持つ水和物スラリを製造するように、冷凍機の蒸発器の冷媒蒸発温度を上げて水和物スラリの温度を上げ、熱密度を小さくする。一方、冷熱負荷が大きいときには、大きな熱密度を持つ水和物スラリを製造するように、冷凍機の蒸発器の冷媒蒸発温度を下げて水和物スラリの温度を下げ、熱密度を大きくする。また、冷熱負荷が大きくなったり小さくなったりする場合には、水和物スラリの熱密度を小さくしたり大きくするように、冷凍機の蒸発器の冷媒蒸発温度を上げたり下げたりする。冷熱負荷が小さいままか、大きいままの場合は水和物スラリの熱密度を小さいままか大きいままに維持するように、冷凍機の蒸発器の冷媒蒸発温度を上げたままか下げたままに維持する。
【００１３】
冷凍機は蒸発器の冷媒蒸発温度が高いほど成績係数（ＣＯＰ）が向上するので、以上のように冷熱負荷に合わせて冷凍機の蒸発器の冷媒蒸発温度を制御して運転することにより、冷凍機の消費電力を低減して成績係数を向上させることができる。
【００１４】
図２に本発明の一実施形態に係る冷熱利用システムの系統図を示す。冷凍機１で製造された水和物スラリは、輸送ポンプ２によって配管３を通して負荷側機器４へ送られ、負荷側機器４から配管５を通して冷凍機１へ戻るように循環する。冷凍機１は、冷媒たとえばフロン系Ｒ１３４ａ、Ｒ２２などを蒸発器、圧縮機、凝縮器および膨張弁を循環させることにより冷却し、冷媒とゲスト化合物を含む水溶液との熱交換により水溶液を冷却して水和物を生成させ水和物スラリを製造するものである。
【００１５】
冷凍機１から負荷側機器４への配管３には第１の熱密度計６が設けられ、負荷側機器４から冷凍機１への配管５には第２の熱密度計７が設けられている。第１の熱密度計６の測定値と第２の熱密度計７の測定値の差に質量流量を乗じた値が負荷側機器４で消費された冷熱量（冷熱負荷）に相当する。第１の熱密度計６の測定値と第２の熱密度計７の測定値は制御装置８に入力され、冷熱負荷が小さいときには制御装置８により冷凍機１を構成する蒸発器の冷媒蒸発温度を上げるように制御し、冷熱負荷に応じて変化させた熱密度を持つ水和物スラリを製造する。このように、冷熱負荷が小さいときには冷凍機１を構成する蒸発器の冷媒蒸発温度を上げることができるので、冷凍機１のＣＯＰを向上させ、冷凍機１の運転での省エネルギー化を図ることができる。
【００１６】
本発明の冷熱利用システムにおいて用いられる熱密度計測方法を図３および図４を参照して説明する。水和物スラリは潜熱を持つ水和物粒子と冷却によって水和物を生成する水溶液とからなる固液混相流体で、水和物スラリの熱密度は基準温度に達するまでに保有している単位質量あたりの熱量を意味し、水和物の持つ潜熱量と水和物ならびに水溶液の顕熱量の和で表される。顕熱量は温度に比例し直線近似できるが、潜熱量は水和物スラリ中の水和物の割合と水和物の潜熱の積によって求まる。ここで水和物スラリ中の水和物の割合を固相率という。このように水和物スラリの熱密度は、温度と固相率を計測することにより求めることができる。
【００１７】
図３に示す第１の熱密度計測方法に用いる熱密度計は以下のように構成されている。たとえば配管３に、水和物スラリの固相率が変化した場合に流量指示値が連動して変化する第１の流量計（たとえば電磁式流量計）１１と、水和物スラリの固相率が変化しても流量指示値が実質的に変化しない第２の流量計（たとえば質量流量計または体積流量計）１２とが直列に配置されている。ここで、第１の流量計１１による流量指示値と第２の流量計１２による流量指示値と、所定濃度の水溶液から製造された水和物スラリの固相率との関係が予め求められ、検量線が作成されている。図３に示す演算器１３には検量線データが記憶されており、第１の流量計１１からの実測流量指示値と第２の流量計１２からの実測流量指示値が入力され、検量線データに当てはめて水和物スラリの固相率が求められる。また、配管３に水和物スラリの温度を計測する温度計１４が配置されている。
【００１８】
次に、水和物スラリの固相率と温度から水和物スラリの熱密度を求める方法を説明する。ＴＢＡＢの水和物には潜熱量の相違する第一水和物（水和数３６）と第二水和物（水和数２６）の２種類が存在する。第一水和物スラリと第二水和物スラリそれぞれの温度と固相率との関係を予め求めておき、温度計１４により計測した水和物スラリの温度と、上記により求めた水和物スラリの固相率から、水和物スラリ中の第一水和物と第二水和物の比率が求められる。
【００１９】
さらに、予め測定されている水和物スラリの固相成分すなわち第一水和物と第一水和物の潜熱量および顕熱量ならびに水溶液成分の顕熱量と、上記のようにして求められた固相率および水和物スラリ中の第一水和物と第二水和物の比率とから、水和物スラリの熱密度が算出される。
【００２０】
上記の方法により水和物スラリの熱密度を計測する熱密度計が冷熱利用システムの負荷側機器の上流側と下流側に設けられ、計測した熱密度の差から冷熱負荷を計測する。
【００２１】
図４に示す第２の熱密度計測方法に用いる熱密度計は以下のように構成されている。たとえば配管５の途中には圧損測定部２１が形成されており、この圧損測定部２１内に圧損要素としてオリフィス２２が設けられている。圧損測定部２１の上流側には、水和物スラリの流量を測定する流量計２３および水和物スラリの温度を測定する温度計２４が設けられている。また、圧損測定部２１のオリフィス２２の上流側と下流側にはそれぞれ圧力計２５，２６が設けられており、オリフィス２２を通過する水和物スラリの圧損（圧力低下）が検出される。これらの流量計２３、温度計２４、圧力計２５，２６からの計測値は演算器２７に送られる。この演算器２７ではこれらの計測値に基づいて水和物スラリの熱密度がオンラインで連続的に算出される。
【００２２】
ここで、水和物スラリの圧力損失は流速と水和物スラリの粘性とに関係するが、圧力損失と粘性の関係が予め求められている。また、所定濃度の水溶液から製造された水和物スラリの固相率と粘性の関係が予め求められる。したがって、流量計２３により水和物スラリの流量を測定するとともに、圧力計２５，２６によりオリフィス２２を通過する水和物スラリの圧損を測定することにより、水和物スラリの粘性が求められ、さらに固相率が求められる。
【００２３】
求めた水和物スラリの温度と固相率から第１の熱密度計測方法と同様に水和物スラリの熱密度が算出される。
【００２４】
上記の方法により、水和物スラリの熱密度を計測する熱密度計が図２に示すように冷熱利用システムの負荷側機器の上流側と下流側に設けられ、計測した熱密度の差から冷熱負荷を計測する。
【００２５】
なお、上記の説明では図４に示す熱密度計を配管５の途中に設けたが、配管５の枝管に設けて設置してもよい。
【００２６】
冷熱負荷に応じて水和物スラリの熱密度を変化させるように、水和物スラリの温度を変化させて製造するために冷凍機の蒸発器の冷媒蒸発温度を制御する方法の実施例を図５に示す。図５に示すように、冷凍機１は冷媒を蒸発器１０１、蒸発圧力制御弁１０２、圧縮機１０３、凝縮器１０４および膨張弁１０５を循環させることにより冷却する。このとき、蒸発圧力制御弁１０２の開度を制御することにより、蒸発器１０１内の圧力を変化させ、冷媒蒸発温度を制御する。図２と同様に、蒸発器１０１内の冷媒とゲスト化合物を含む水溶液との熱交換により水溶液を冷却して水和物を生成させ水和物スラリが製造され、製造された水和物スラリは輸送ポンプ２によって配管３を通して負荷側機器４へ送られ、負荷側機器４から配管５を通して冷凍機１へ戻るように循環する。また、冷凍機１から負荷側機器４への配管３には第１の熱密度計６が設けられ、負荷側機器４から冷凍機１への配管５には第２の熱密度計７が設けられている。シーケンサー１１０内の２つの演算器１３、１３によってそれぞれ計測された第１の熱密度計６の測定値と第２の熱密度計７の測定値に基づいて、冷熱負荷演算器１１１により冷熱負荷が演算される。冷熱負荷が小さいときには水和物スラリの温度を高くし熱密度を小さくするように、蒸発器１０１の冷媒蒸発温度を上げるように制御する。冷熱負荷の演算結果が、蒸発圧力制御弁制御器１２０に入力されて蒸発圧力制御弁１０２の開度をＰＩＤ制御し、上述したように蒸発器１０１内の圧力を変化させ、冷媒蒸発温度を制御する。このように冷熱負荷が小さいときは蒸発器１０１の冷媒蒸発温度を上げることができるので、冷凍機１のＣＯＰを向上させ省エネルギーを図ることができる。
【００２７】
蒸発圧力制御弁制御器１２０は冷凍機１と一体となす場合や、冷凍機１と分離されている場合があるが、シーケンサ１１０とともに冷凍機の運転を制御する装置を構成している。また、蒸発圧力制御弁制御器１２０が冷凍機１の一部である場合、シーケンサ１１０が冷凍機の運転を制御する装置を構成する。
【００２８】
【発明の効果】
以上詳述したように本発明によれば、顕熱と潜熱を利用でき高い熱密度を持つ冷熱輸送媒体として水和物スラリを用いた冷熱利用システムで、負荷に見合った熱密度を持つ水和物スラリを製造することにより冷凍機を高い成績係数で運転でき、省エネルギー化を図ることができる。
【図面の簡単な説明】
【図１】ＴＢＡＢ水和物スラリについて、温度と比エンタルピとの関係を示す図。
【図２】本発明の一実施形態に係る冷熱利用システムを示す系統図。
【図３】本発明において用いられる熱密度計の一例を示す構成図。
【図４】本発明において用いられる熱密度計の他の例を示す構成図。
【図５】本発明における冷凍機の蒸発器の冷媒蒸発温度を制御する機構の一例を示す系統図。
【符号の説明】
１…冷凍機
２…輸送ポンプ
３，５…配管
４…負荷側機器
６…第１の熱密度計
７…第２の熱密度計
８…制御装置
１１…第１の流量計
１２…第２の流量計
１３…演算器
１４…温度計
２１…圧損測定部
２２…オリフィス
２３…流量計
２４…温度計
２５，２６…圧力計
２７…演算器
１０１…蒸発器
１０２…蒸発圧力制御弁
１０３…圧縮機
１０４…凝縮器
１０５…膨張弁
１１０…シーケンサー
１１１…冷熱負荷演算器
１２０…蒸発圧力制御弁制御器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cold utilization system utilizing hydrate slurry as cold transport medium.
[0002]
[Prior art]
In the field of cooling and industrial refrigeration systems, by increasing the transport heat density of the refrigeration medium, the flow rate is reduced, the transport pump power is reduced, the transport pipe power is reduced, and the piping cost and construction are reduced. Attempts have been made to reduce costs. As a means for increasing the transport heat density of a cold medium, a technique using a cold transport medium that utilizes latent heat during a solid-liquid phase change in addition to sensible heat is known. For example, an ice-water slurry using sensible heat of water and latent heat of melting of ice is currently being tried as a cold transport medium having a high heat density.
[0003]
When a refrigeration transport medium having a high heat density that can use sensible heat and latent heat is used in a cooling or industrial refrigeration system, it is desired to supply the chill transport medium with a cold amount corresponding to the cold load. As a means for this, when ice water slurry is used as a cold transport medium, in order to reduce the amount of transport cold heat, the capacity of the refrigerator is controlled to perform partial load operation, and the proportion of ice in the ice water slurry is reduced to reduce the amount of cold heat. A method of reducing the transport heat density has been considered.
[0004]
However, when using a cold transport medium that has a constant temperature at the time of phase change, such as ice, it is necessary to keep the refrigerant evaporation temperature of the evaporator constituting the refrigerator constant even during partial load operation of the refrigerator. There is. For this reason, the operation method of raising the refrigerant | coolant evaporation temperature of an evaporator and improving the coefficient of performance (COP) of a refrigerator cannot be employ | adopted, but the fall of COP resulting from partial load operation only arises.
[0005]
[Problems to be solved by the invention]
An object of the present invention, sensible heat and latent using hydrate slurry as cold transport medium having a high heat density available, cold heat that can improve the performance coefficient of the refrigeration for the production of the hydrate slurry The purpose is to provide a usage system.
[0006]
[Means for Solving the Problems]
The cold energy utilization system according to the present invention includes a refrigerator that cools an aqueous solution of a guest compound that produces a hydrate to produce a hydrate slurry, and a pipe that communicates the refrigerator and a load-side device that utilizes cold energy. A first heat density meter provided in a pipe from the refrigerator to a load side device, and a second heat density meter provided in a pipe from the load side device to the refrigerator. The cold load is measured from the difference in heat density between the heat density meter and the hydrate slurry obtained from the first and second heat density meters, and the heat density of the hydrate slurry is changed according to the cold load. And a device for controlling the operation of the refrigerator as manufactured.
[0007]
In one embodiment, the cold energy utilization system includes a first heat density meter, a first flow rate indicator, and a flow rate instruction value that changes in conjunction with a change in a solid phase ratio of the hydrate slurry. A flow meter, a second flow meter in which the flow rate indication value does not change even if the solid fraction of the hydrate slurry changes, a thermometer that measures the temperature of the hydrate slurry, and the first and second And a calculator for calculating the heat density of the hydrate slurry based on the measured flow rate instruction value from each of the flow meters and the temperature measured by the thermometer.
[0008]
In another aspect, in the cold utilization system, each of the first and second heat density meters is provided on an orifice and a first pressure gauge provided on the upstream side of the orifice and on a downstream side of the orifice. A pressure loss measuring unit comprising a second pressure gauge, a flow meter for measuring the flow rate of the hydrate slurry, and a thermometer for measuring the temperature of the hydrate slurry, provided upstream of the pressure loss measuring unit. And an arithmetic unit for calculating the heat density of the hydrate slurry based on the measured values from the first and second pressure gauges, the flowmeter and the thermometer.
[0009]
An apparatus for controlling the operation of the refrigerator in the cold energy utilization system includes, for example, an apparatus for controlling the refrigerant evaporation temperature of an evaporator constituting the refrigerator.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
When an aqueous solution of a guest compound such as tetra-n-butylammonium salt, tetraiso-amylammonium salt, tetraiso-butylphosphonium salt, triiso-amylsulfonium salt is cooled, the hydrate of the guest compound is formed at a temperature of 0 ° C. or higher. It forms and becomes a hydrate slurry in which a hydrate is dispersed in an aqueous solution. Such a hydrate slurry has a latent heat at the time of a solid-liquid phase change in which a hydrate solid is generated by cooling from an aqueous solution in which a guest compound is dissolved, and thus can be used as a cold transport medium having a high heat density.
[0011]
FIG. 1 shows the relationship between the temperature based on a slurry temperature of 12 ° C. and the specific enthalpy for tetra n-butylammonium bromide (TBAB) hydrate slurry as a representative example of hydrate slurry. As shown in this figure, the hydrate slurry has the characteristic of having latent heat in a certain temperature range. That is, when the temperature of the hydrate slurry is high, the heat density is low, and when the temperature of the hydrate slurry is low, the heat density is high. For this reason, when using a hydrate slurry as a cold transport medium for a cold energy utilization system, when the load on the load side equipment is small, the heat density is reduced by increasing the temperature of the hydrate slurry within the range where latent heat can be used. Is possible. This means that when the cooling load is small, operation can be performed by increasing the refrigerant evaporation temperature of the evaporator of the refrigerator that cools the aqueous solution of the guest compound, for example, so as to increase the temperature of the hydrate slurry.
[0012]
Therefore, when the cooling load is small, the refrigerant evaporation temperature of the evaporator of the refrigerator is increased to increase the temperature of the hydrate slurry so as to produce a hydrate slurry having a small heat density according to the cooling load. Reduce the density. On the other hand, when the cold load is large, the refrigerant evaporation temperature of the evaporator of the refrigerator is lowered to lower the temperature of the hydrate slurry so as to produce a hydrate slurry having a large heat density, thereby increasing the heat density. Further, when the cooling load is increased or decreased, the refrigerant evaporation temperature of the evaporator of the refrigerator is increased or decreased so as to decrease or increase the heat density of the hydrate slurry. Keep the refrigeration evaporator's refrigerant evaporation temperature either raised or lowered so that the thermal density of the hydrate slurry remains small or large if the cold load remains small or large To do.
[0013]
Since the coefficient of performance (COP) of a refrigerator increases as the refrigerant evaporation temperature of the evaporator increases, the refrigerant is operated by controlling the refrigerant evaporation temperature of the evaporator of the refrigerator according to the cooling load as described above. The coefficient of performance can be improved by reducing the power consumption of the machine.
[0014]
FIG. 2 shows a system diagram of a cold energy utilization system according to an embodiment of the present invention. The hydrate slurry produced by the refrigerator 1 is sent to the load side device 4 through the pipe 3 by the transport pump 2 and circulates back from the load side device 4 to the refrigerator 1 through the pipe 5. The refrigerator 1 cools the refrigerant, for example, chlorofluorocarbons R134a and R22 by circulating the evaporator, the compressor, the condenser, and the expansion valve, and cools the aqueous solution by heat exchange between the refrigerant and the aqueous solution containing the guest compound. Hydrate is produced to produce a hydrate slurry.
[0015]
The pipe 3 from the refrigerator 1 to the load side device 4 is provided with a first heat density meter 6, and the pipe 5 from the load side device 4 to the refrigerator 1 is provided with a second heat density meter 7. Yes. A value obtained by multiplying the difference between the measurement value of the first heat density meter 6 and the measurement value of the second heat density meter 7 by the mass flow rate corresponds to the amount of cooling energy (cooling load) consumed by the load side device 4. The measurement value of the first heat density meter 6 and the measurement value of the second heat density meter 7 are input to the control device 8, and when the cooling load is small, the refrigerant evaporation temperature of the evaporator constituting the refrigerator 1 by the control device 8. A hydrate slurry having a heat density that is controlled according to the cooling load is produced. As described above, when the cooling load is small, the refrigerant evaporation temperature of the evaporator constituting the refrigerator 1 can be raised, so that the COP of the refrigerator 1 can be improved and energy saving in the operation of the refrigerator 1 can be achieved. it can.
[0016]
A heat density measurement method used in the cold energy utilization system of the present invention will be described with reference to FIGS. Hydrate slurry is a solid-liquid mixed phase fluid consisting of hydrate particles with latent heat and an aqueous solution that produces hydrates by cooling, and the thermal density of the hydrate slurry is the unit held by the time it reaches the reference temperature. It means the amount of heat per mass, and is expressed as the sum of the latent heat amount of the hydrate and the sensible heat amount of the hydrate and aqueous solution. The amount of sensible heat is proportional to the temperature and can be linearly approximated, but the amount of latent heat is determined by the product of the ratio of the hydrate in the hydrate slurry and the latent heat of the hydrate. Here, the ratio of the hydrate in the hydrate slurry is called the solid phase ratio. Thus, the heat density of the hydrate slurry can be determined by measuring the temperature and the solid fraction.
[0017]
The heat density meter used in the first heat density measuring method shown in FIG. 3 is configured as follows. For example, in the pipe 3, when the solid phase ratio of the hydrate slurry changes, the first flow meter (for example, an electromagnetic flow meter) 11 in which the flow rate indication value changes in conjunction with the solid phase ratio of the hydrate slurry, A second flow meter (for example, a mass flow meter or a volumetric flow meter) 12 in which the flow rate instruction value does not substantially change even when the value changes is arranged in series. Here, the relationship between the flow rate instruction value by the first flow meter 11, the flow rate instruction value by the second flow meter 12, and the solid phase ratio of the hydrate slurry produced from the aqueous solution having a predetermined concentration is obtained in advance. A calibration curve has been created. Calibration curve data is stored in the calculator 13 shown in FIG. 3, and the actual flow rate instruction value from the first flow meter 11 and the actual flow rate instruction value from the second flow meter 12 are input, and the calibration curve data is input. To determine the solid phase ratio of the hydrate slurry. Further, a thermometer 14 for measuring the temperature of the hydrate slurry is disposed in the pipe 3.
[0018]
Next, a method for obtaining the heat density of the hydrate slurry from the solid phase ratio and temperature of the hydrate slurry will be described. There are two types of TBAB hydrates: a first hydrate (hydration number 36) and a second hydrate (hydration number 26) having different latent heat amounts. The relationship between the temperature and the solid phase ratio of each of the first hydrate slurry and the second hydrate slurry is determined in advance, and the hydrate slurry temperature measured by the thermometer 14 and the hydrate determined as described above. From the solid phase ratio of the slurry, the ratio of the first hydrate and the second hydrate in the hydrate slurry is obtained.
[0019]
Further, the solid phase component of the hydrate slurry, that is, the latent heat amount and the sensible heat amount of the first hydrate and the first hydrate, and the sensible heat amount of the aqueous solution component, and the solid amount obtained as described above are measured. The thermal density of the hydrate slurry is calculated from the phase ratio and the ratio of the first hydrate and the second hydrate in the hydrate slurry.
[0020]
A heat density meter for measuring the heat density of the hydrate slurry by the above method is provided on the upstream side and the downstream side of the load side device of the cold energy utilization system, and the cold load is measured from the difference of the measured heat density.
[0021]
The heat density meter used in the second heat density measuring method shown in FIG. 4 is configured as follows. For example, a pressure loss measuring unit 21 is formed in the middle of the pipe 5, and an orifice 22 is provided as a pressure loss element in the pressure loss measuring unit 21. A flow meter 23 that measures the flow rate of the hydrate slurry and a thermometer 24 that measures the temperature of the hydrate slurry are provided on the upstream side of the pressure loss measurement unit 21. In addition, pressure gauges 25 and 26 are provided on the upstream side and the downstream side of the orifice 22 of the pressure loss measuring unit 21, respectively, and the pressure loss (pressure drop) of the hydrate slurry passing through the orifice 22 is detected. Measurement values from the flow meter 23, the thermometer 24, and the pressure gauges 25 and 26 are sent to the calculator 27. In this calculator 27, the heat density of the hydrate slurry is continuously calculated on-line based on these measured values.
[0022]
Here, the pressure loss of the hydrate slurry is related to the flow velocity and the viscosity of the hydrate slurry, but the relationship between the pressure loss and the viscosity is obtained in advance. Further, the relationship between the solid phase ratio and viscosity of a hydrate slurry produced from an aqueous solution having a predetermined concentration is obtained in advance. Therefore, by measuring the flow rate of the hydrate slurry with the flow meter 23 and measuring the pressure loss of the hydrate slurry passing through the orifice 22 with the pressure meters 25 and 26, the viscosity of the hydrate slurry is obtained, Furthermore, the solid phase ratio is required.
[0023]
The heat density of the hydrate slurry is calculated from the obtained temperature and solid fraction of the hydrate slurry in the same manner as in the first heat density measurement method.
[0024]
With the above method, a heat density meter for measuring the heat density of the hydrate slurry is provided on the upstream side and the downstream side of the load side equipment of the cold energy utilization system as shown in FIG. Measure the load.
[0025]
In the above description, the heat density meter shown in FIG. 4 is provided in the middle of the pipe 5, but it may be provided in a branch pipe of the pipe 5.
[0026]
An example of a method for controlling the refrigerant evaporation temperature of the evaporator of a refrigerator to produce by changing the temperature of the hydrate slurry so as to change the heat density of the hydrate slurry according to the cold load. As shown in FIG. As shown in FIG. 5, the refrigerator 1 cools the refrigerant by circulating it through an evaporator 101, an evaporation pressure control valve 102, a compressor 103, a condenser 104, and an expansion valve 105. At this time, by controlling the opening degree of the evaporation pressure control valve 102, the pressure in the evaporator 101 is changed to control the refrigerant evaporation temperature. As in FIG. 2, a hydrate slurry is produced by cooling the aqueous solution by heat exchange between the refrigerant in the evaporator 101 and the aqueous solution containing the guest compound to produce a hydrate slurry, and the produced hydrate slurry is It is sent to the load side device 4 through the pipe 3 by the transport pump 2 and circulates back from the load side device 4 to the refrigerator 1 through the pipe 5. The pipe 3 from the refrigerator 1 to the load side device 4 is provided with a first heat density meter 6, and the pipe 5 from the load side device 4 to the refrigerator 1 is provided with a second heat density meter 7. It has been. Based on the measured value of the first heat density meter 6 and the measured value of the second heat density meter 7 respectively measured by the two calculators 13 and 13 in the sequencer 110, the cooling load is calculated by the cooling load calculator 111. Calculated. When the cooling load is small, control is performed to raise the refrigerant evaporation temperature of the evaporator 101 so as to increase the temperature of the hydrate slurry and reduce the heat density. The calculation result of the cooling load is input to the evaporation pressure control valve controller 120, the opening degree of the evaporation pressure control valve 102 is PID-controlled, and the pressure in the evaporator 101 is changed as described above to control the refrigerant evaporation temperature. To do. Thus, when the cooling load is small, the refrigerant evaporation temperature of the evaporator 101 can be raised, so that the COP of the refrigerator 1 can be improved and energy saving can be achieved.
[0027]
The evaporation pressure control valve controller 120 may be integrated with the refrigerator 1 or may be separated from the refrigerator 1, but constitutes a device that controls the operation of the refrigerator together with the sequencer 110. Further, when the evaporation pressure control valve controller 120 is a part of the refrigerator 1, the sequencer 110 constitutes an apparatus for controlling the operation of the refrigerator.
[0028]
【Effect of the invention】
As described above in detail, according to the present invention, a refrigeration system using a hydrate slurry as a refrigeration transport medium that can utilize sensible heat and latent heat and has a high heat density, hydration having a heat density corresponding to the load. By manufacturing the material slurry, the refrigerator can be operated with a high coefficient of performance, and energy saving can be achieved.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between temperature and specific enthalpy for a TBAB hydrate slurry.
FIG. 2 is a system diagram showing a cold energy utilization system according to an embodiment of the present invention.
FIG. 3 is a configuration diagram showing an example of a heat density meter used in the present invention.
FIG. 4 is a configuration diagram showing another example of a heat density meter used in the present invention.
FIG. 5 is a system diagram showing an example of a mechanism for controlling the refrigerant evaporation temperature of the evaporator of the refrigerator according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Refrigerator 2 ... Transport pump 3, 5 ... Pipe 4 ... Load side apparatus 6 ... 1st heat density meter 7 ... 2nd heat density meter 8 ... Control apparatus 11 ... 1st flow meter 12 ... 2nd Flow meter 13 ... Calculator 14 ... Thermometer 21 ... Pressure loss measuring unit 22 ... Orifice 23 ... Flow meter 24 ... Thermometer 25, 26 ... Pressure gauge 27 ... Calculator 101 ... Evaporator 102 ... Evaporation pressure control valve 103 ... Compressor 104 ... Condenser 105 ... Expansion valve 110 ... Sequencer 111 ... Cold load calculator 120 ... Evaporation pressure control valve controller

Claims

A cold energy utilization system comprising a refrigerator that cools an aqueous solution of a guest compound that forms a hydrate to produce a hydrate slurry, and a piping system that communicates the refrigerator with a load-side device that utilizes cold energy. A first heat density meter provided in a pipe from the refrigerator to a load side device, a second heat density meter provided in a pipe from the load side device to the refrigerator, the first and Operation of the refrigerator so as to measure the cold load from the difference in heat density of the hydrate slurry obtained from the second heat density meter, and to produce by changing the heat density of the hydrate slurry according to the cold load. ; and a control device,
Each of the first and second heat density meters includes a first flow meter in which the flow rate indication value changes in conjunction with a change in the solid fraction of the hydrate slurry, and a solid fraction of the hydrate slurry. The flow rate instruction value does not change even if the flow rate changes, the thermometer that measures the temperature of the hydrate slurry, the actual flow rate instruction value from each of the first and second flow meters, and the A cold energy utilization system comprising: an arithmetic unit that calculates a heat density of a hydrate slurry based on a temperature measured by a thermometer .

A cold energy utilization system comprising a refrigerator that cools an aqueous solution of a guest compound that forms a hydrate to produce a hydrate slurry, and a piping system that communicates the refrigerator with a load-side device that utilizes cold energy. A first heat density meter provided in a pipe from the refrigerator to a load side device, a second heat density meter provided in a pipe from the load side device to the refrigerator, the first and Operation of the refrigerator so as to measure the cold load from the difference in heat density of the hydrate slurry obtained from the second heat density meter, and to produce by changing the heat density of the hydrate slurry according to the cold load. ; and a control device,
Each of the first and second heat density meters includes an orifice, a first pressure gauge provided on the upstream side of the orifice, and a second pressure gauge provided on the downstream side of the orifice. A flow meter for measuring the flow rate of the hydrate slurry, a thermometer for measuring the temperature of the hydrate slurry, the first and second pressure meters, provided on the upstream side of the pressure loss measuring unit, A cold utilization system comprising: a flow meter and an arithmetic unit that calculates a heat density of the hydrate slurry based on a measured value from the thermometer .

The cold energy utilization system according to claim 1 or 2 , wherein the device that controls the operation of the refrigerator includes a device that controls a refrigerant evaporation temperature of an evaporator constituting the refrigerator.