DE4105404A1 - Cooling system for holding a chemical reaction at a required temperature - has three heat exchangers connected to cooling pump - Google Patents

Abstract

The chemical reaction occurs in the reactor (R1) which is held at the required reaction temperature either by heating or by cooling. The reactor can be connected to any one of three heat exchanges (W1-W3) which are held at temperatures of 180 deg. C, 40 deg. C and -15 deg. C respectively. The three heat exchanges are connected in parallel to a cooling circuit, in which a cooling liquid is circulated by a pump (P1) and held at the required pressure by nitrogen which is supplied through a pressure control valve (PC). The high temperature heat exchanger (W1) is supplied with high pressure steam, the medium temperature heat exchanger (W2) is supplied with cooling water, and the low temperature heat exchanger is supplied with brine. USE/ADVANTAGE - Maintaining a chemical reaction at the required temperature between -20 deg. C and 200 deg. C.

Description

The invention relates to a heating system constructed with a pump. and cooling system, which by appropriate pressure control in several re circuits with different temperature levels divided becomes.

For the production of various products are in stirred tanks different physico-chemical processes in batch ver driving done. When performing these reactions is precise temperature control is necessary because the quality of the Decide the product and the reproducibility of the approach depend on it. The temperature range runs through values from -25 to + 200 ° C (also with heat transfer systems much higher).

For heating and cooling such batch processes The following procedures were used:

• - Steam heating and water cooling
• - Hot water circuits with steam or water intake according to the regulation (open systems)
• - Pressurized water circuits with injection (steam) and steam direct supply of cooling water. The ejection follows via a level control
• - Pressurized water circuit with blowing (nozzle) of steam and in direct water cooling
• - Pressurized water circuit with two primary circulation systems (hot and cold) and a secondary circuit

The open heating and cooling systems are characterized by numerous after parts marked:

• - high corrosion in the system
• - If leakages occur, pollutants from the reactor (water hazardous substances) un controlled via the cooling water system in the Waters
• - unfavorable control behavior (two-phase system)

For hydraulic fluid circuits with direct steam and Cooling water supply, the disadvantages mentioned are also present. If cooling takes place indirectly via heat exchangers, so verbes Corrosion conditions change, but it remains discharge to be carried out under pressure (level control) of the excess water. Besides, this system is only on Limited pressure water and thus in the area of lower temperatures (water-glycol mixture) cannot be used.

The hydraulic fluid circuit system with primary and secondary circuits that are mixed with a single substance medium (e.g. water / Gly kol) works, avoids the disadvantages of the mentioned Process, however, is apparatus, piping and control technically complex. Since this is also a central one Generation of primary energies (hot / cold) is the Use only useful with several on the energy rails closed reactors. (Thier, B .: Temperature control systems for batch processes with integrated cold system. 3R international 29 (1990) 12, pp. 644-648.)

In the developed process, the circulatory system with a pump through appropriate circuits and pressure control Main and secondary circuits are formed, which are different Have temperatures and thus for a cyclical heating and Cooling technology can be used.

In the flow diagram drawing no. T10-01-01 is the procedure and the circuit of the heating and cooling circuit tert.  

The pump P 1 is used to set up the main circuit, which runs via the pressure control (PC) and the expansion tank B 1 and is expanded to a nitrogen-superimposed pressure system (system pressure). Corresponding regulations and pressure safeguards as well as the level measurement are shown on container B 1 .

At the pressure port of the pump P 1 , three secondary circuits are connected, which lead to the heat exchangers W 1 , W 2 and W 3 , in which different temperatures are set (example 180 ° C; 40 ° C; -15 ° C). The heat exchangers W 1 , W 2 and W 3 are heated or cooled by energy rails (high-pressure steam; cooling water; brine) with supply and return lines using appropriate temperature control (TIC). The three heat exchangers W 1 , W 2 , W 3 are located in a closed branch of the secondary circuit, the lower end being made by a non-return flap, while the upper end is made by the control valves (control valves) RV 1 , RV 2 and RV 3 . This prevents the three different temperature systems from exchanging. To secure the pressure z. B. with temperature-related volume expansion safety valves (SV) are provided.

The heating and cooling system is controlled via the temperature cascade (TRCSA) of the reactor R 1 and the cyclical opening of the control valves (RV 1 , RV 2 , RV 3 ).

Due to the pressure build-up of pump P 1 , the pressure in the main circuit (pressure control PC) and in the secondary circuits is approx. 1-3 bar higher than in the pressure system, which is set by the N₂ pressure regulator.

By switching and pressure control, the following operation can can be achieved:

• - the main circuit via pump P 1 runs continuously via the pressure control (PC) (general operating phase)
• - If the reactor R 1 is started up via the control (TRCSA), the control valve RV 1 opens and the heating medium flows through the heat exchanger W 1 into the jacket space of the reactor R 1 (heating phase)
• - When the temperature in the reactor R 1 is reached, the reaction starts and heat develops (exothermic reaction). This means that the heating control valve RV 1 closes and the cooling valve RV 2 opens, thus setting a corresponding Δt to dissipate the heat (cooling phase)
• - For the temperature control of the process below the cooling water level (e.g. crystallization) there is an additional secondary circuit with -15 ° C (W 3 ), whereby the RV3 control valve opens in the cycle of the temperature cascade and corresponding cold liquid flows in (Freezing phase)

Only one is used as heating and cooling medium in the entire system Substance (e.g. water-ethylene glycol) is used so that all circles runs can be run through (single-substance system).

The heating and cooling system according to the invention has the following share on:

• - Closed pressure under nitrogen fluid system
• - no corrosion
• - Collection system for any water-polluting pollutants from the reactor (if leaks occur)  
• - Good control options with multiple components different temperature values (mixed control)
• - circulatory system with one pump
• - Division of this system into main and secondary circuits with different temperature levels
• - Individual temperature control for a boiler system in the limit range from approx. -20 ° C to + 200 ° C.

Claims (6)

Closed and nitrogen pressurized liquid circulation system, characterized by : 1. Circuit of the pump system to one main and several Secondary circuits with different temperature values. 2. Structure of different printing systems within one Pump circuit. 3. Use of single-component systems as heat-coolant Medium for all temperature ranges. 4. Integrate the heating and cooling system with those in the Temperature different secondary circuits in the Control loop of the reactor (temperature cascade). 5. Installation of non-return valves below the heat exchanger exchanger to a backflow of in temperature to prevent different media flows.